Humpback whale populations migrate extensively between winter breeding grounds and summer feeding grounds, however known links to remote Antarctic feeding grounds remain limited in many cases. New satellite tracks detail humpback whale migration pathways from Western Australia into the Southern Ocean. These highlight a focal feeding area during austral spring and early summer at the southern Kerguelen plateau, in a western boundary current where a sharp northward turn and retroflection of ocean fronts occurs along the eastern plateau edge. The topographic steering of oceanographic features here likely supports a predictable, productive and persistent forage ground. The spatial distribution of whaling catches and Discovery era mark-recaptures confirms the importance of this region to Western Australian humpback whales since at least historical times. Movement modelling discriminates sex-related behaviours, with females moving faster during both transit and resident periods, which may be a consequence of size or indicate differential energetic requirements. Relatively short and directed migratory pathways overall, together with high-quality, reliable forage resources may provide a partial explanation for the ongoing strong recovery demonstrated by this population. The combination of new oceanographic information and movement data provides enhanced understanding of important biological processes, which are relevant within the context of the current spatial management and conservation efforts in the Southern Ocean. Megaptera novaeangilae) migrations, between low-latitude winter breeding grounds and high-latitude summer feeding areas, represent one of the most extensive3 and consistent mammalian migrations known. For Southern Hemisphere populations, early knowledge of humpback whale (HBW) movements were derived from commercial catch distributions and basic Discovery tag mark-recaptures5. Further insight has developed from modern photo-identification and molecular methods8 and the current management of seven distinct Southern Hemisphere populations (A–G), under the International Whaling Commission (IWC), is increasingly informed by sophisticated genetic analyses (e.g.13).Humpback whale (14. Western (breeding stock D) and Eastern Australian (breeding stock E1) populations have amongst the highest increase rates estimated, in the order of 9–12.7% (see15 and references therein) and 11.0%16, respectively. In contrast, the neighbouring Oceania population  remains listed as endangered by the International Union for Conservation of Nature17 and show no apparent recovery trend18 . Factors controlling divergent population trajectories are unknown, and it is difficult to disentangle the historical harvest impact20 – including decimation from illegal hunting21 – from current environmental and/or anthropogenic factors. However, improved understanding of HBW feeding grounds may elucidate the role of factors such as migration length and energetic requirements in regulating recovery22, and provide an improved context for understanding likely impacts of future ecosystem changes25.Recovery patterns following intensive industrial whaling vary across populations, with differing levels of uncertainty, but the recent comprehensive assessment by the IWC Scientific Committee projected the Western Australian (WA) population to have the highest abundance, in the range of 18,415–24,91822). Satellite telemetry is helping to clarify migratory routes, providing detailed information about key corridors, important habitats and potential for overlap with human activities33. Here, we present the first high-resolution migratory pathways to Southern Ocean summer forage grounds for the WA HBW population.Links between specific breeding grounds and remote, relatively unsurveyed Antarctic feeding grounds remain poorly understood in many cases . One female headed to the northern Kerguelen plateau (ID131140); one continued in a more southward route towards the ice edge, staying east of 95°E (ID154859); only intermittent records appeared from ID154876 near 102°E, 52°S; and one tag failed during early transit . The other 8 out of 12 animals (67%) all travelled towards the southern Kerguelen plateau (SKP).HBWs migrated southwest towards the Kerguelen plateau in the Indian sector of the Southern Ocean, being tracked over total distances of 3551 to 11474 km . Tracks of six individual whales show a notable focus along the eastern flank of the SKP, between the Southern Boundary and the southern Antarctic Circumpolar Current (ACC) front Fig. . Here, tWhales continued to occupy this frontal area and Banzare Bank during November and December, well after the sea-ice has retreated southward , but not on the state transition probabilities (Supplementary µ) of 5.15 km h−1 for females (CI: 4.78–5.51), in comparison to 3.16 km h−1 (CI: 2.94–3.38) for males and 4.00 km h−1 (CI: 3.69–4.30) for unsexed animals. The movement estimates for the resident state were much lower overall . Across sexes, more directed movements were evident from mean turn angles (λ) close to zero during transit, whereas values close to Κ) during transit, albeit this appeared rather weaker for males . Across sexes the concentration parameter estimates were generally close to zero during residency , with the last location estimate for female ID113220 being at the Area III boundary  just prior to tag failure Fig. . Over 5,32 confirm some movement occurs into Area IV from the east; one of these females spent time near 120°E before moving as far west as 108°E, where the track terminated. One WA female from an earlier deployment41 migrated quite directly south, also towards 120°E, further suggesting some overlapping of foraging ranges for Eastern and Western humpback whales. Reported whaling catches west of the SKP are comparatively low until the Weddell gyre. Sparse tracking records from eastern South African HBW (stock C) have recently documented movement towards the Crozet and Prince Edward Islands, and westward of 30°E .The spatial distribution of whaling catches Fig.  supports40.The detailed migration pathways presented here enrich our knowledge of the long-distance migrations undertaken by WA humpback whales and their usage of important Southern Ocean seasonal feeding grounds. This new information is relevant within the context of the current spatial management and conservation efforts to protect marine areas in the East Antarctic/Indian Ocean sector. While our findings are consistent with existing general knowledge of HBW movement patterns, the high-resolution biotelemetry reveals specific usage of the western boundary current at the southern Kerguelen plateau. The high productivity around the SKP, controlled by the interaction of topography and oceanography, is likely to provide a predictable, persistent and high-quality forage resource for whales42. The spatial distribution of whaling catches . In fact blue whale  catches show a very similar spatial distribution in this sector43, and regional survey sightings of humpback, blue, sperm  and minke (B. cutorostra) whales44 indicate the southern Kerguelen plateau is important to other baleen and toothed whales. Ship-based survey sightings highlight cetacean densities around the southern and eastern flanks of the SKP40. Both catch and survey data show generally high cetacean densities extend farther northward  directly east of the southern Kerguelen plateau45.Simplified movement patterns of HBWs derived from early Discovery mark recoveries show a clear connectivity between the low-latitude WA breeding grounds and high-latitude feeding grounds in the Indian sector of the Southern Oceanhes Fig.  further 45. The phytoplankton bloom southeast of the SKP has been shown to be persistent throughout the summer35 with a number of interplaying mechanisms hypothesized to support this sustained productivity, including: topographic upwelling, ice edge blooms, the advection of biomass and/or nutrients from the south, and potentially gyre retention (see discussions by Sokolov and Rintoul34 and Rintoul and colleagues35). The regional surface ocean circulation and frontal structure, including sharp northward turn and retroflection of the fronts in a western boundary current along the eastern plateau margin , was described during a recent marine ecosystem voyage  the summer prior to our main tracking dataset. The topographic steering of currents dictates both the southern extent of the ACC and the northern limit of subpolar waters, which likely influences the distribution and productivity of marine ecosystem at multiple trophic levels37.These cetacean distributions reflect the overall patterns of regional biological productivity and oceanographic processesgin Fig.  and37, win situ and satellite chlorophyll-a concentrations, Schallenberg and co-authors36 concluded the regional ocean circulation plays an important role in supplying the iron necessary to sustain these persistent blooms. The northward horizontal advection of subsurface iron, likely originating from Antarctic shelf sediments in the south, and subsequent upwelling – along the eastern margin of the SKP and in association with frontal processes – combine to create a biological hotspot. This new research clarifying biophysical linkages provides a deepened understanding of the importance of this feeding ground to migrating HBWs, where the conditions support predictable and persistent high biological productivity. We speculate that this feeding scenario may be more favourable than using more dispersed and/or ephemeral resources, such as oceanic or marginal-ice zone foraging. The bathymetric control of currents and regional productivity might also be more resilient to change.Examining KAXIS dissolved iron measurements within the broader context of 33 show highly dispersed trajectories, spread across around 4500 km of Antarctic feeding grounds. Notably, of these Oceania HBWs the tagged mother-calf pairs showed the shortest migrations, moving more directly south to the Ross Sea (~4500 km). Adults without dependant calves predominantly moved into the Bellingshausen and Amundsen Seas, showing that minimum straight-line distances over 6000 km are not exceptional2. Other extreme long-distance HBW movements (>8000 km) can occur between feeding areas along the Antarctic Peninsula and breeding areas off Central America1.The location of the SKP feeding grounds additionally appears to result in relatively direct travel pathways for WA HBWs. For example, WA HBW net displacements approached a maximum of around 5500 km from the tagging location Table , showing33. Reported straight-line distances from assigned breeding grounds ranged from ~900 km  to ~2000 km , and included assigned origins at New Caledonia , Niue (~1300 km) and American Samoa (~1800 km). French Polynesia is also a breeding site for Oceania HBWs46 therefore a straight line distance of 3000–3500 km is also a possibility. HBWs have a breeding ground preference for shallow coastal waters and bays47 and recent work has expanded the recognized calving grounds for the WA HBW population (breeding stock D) along the extensive coastline of north-western Australia, from Camden Sound in the Kimberley (15°S) to at least North West Cape (22°43’S)48. Of those WA HBWs that we tracked into the Southern Ocean, only one was tagged on its northbound trip. This individual showed a northernmost terminus (turning point) at 114.93°E, 20.38°S (Table 49 were 1220 ± 443 km (range: 228–1771 km). Overall, these investigations suggest that WA breeding ground movements are likely to be of a similar, or somewhat smaller, scale than the comparable movements of Oceania HBWs.It is worth noting that neither study (WA nor Oceania HBWs) tagged whales on the breeding grounds, but in both cases the total migratory pathway includes substantial movement from breeding sites to the tagging locations. On the basis of photo identification and genetic matches HBWs passing the Kermadec Islands did not assign to a single Oceania breeding ground origin, but instead came from a range of breeding grounds spanning ~3500 km of ocean°S Table , approxi°S Table . The tra°S Table  reveal o47. It seems likely that these three important elements are together potentially facilitating the strong recovery of the WA population22: the availability of suitable breeding, calving and resting areas along the WA coast47, a relatively direct migration (compared to other HBW populations), and temporally persistent high-quality prey in a productive boundary-current ecosystem.The energetic costs of these different migration distances remain to be evaluated in comparison to the energetic benefits obtained from favourable feeding grounds, and/or favourable breeding grounds 50. Baleen plates from a small number of stranded WA HBWs (n = 7) showed isotopic profiles consistent with continual provisioning, or dietary provenance, from a low trophic-level Antarctic prey source. In comparison, isotopic profiles of 13 East Australian (stock E1) animals showed this population was more likely to feed outside the traditional Antarctic zone; for example, with supplementary temperate feeding as has been regularly reported53. Recent satellite tracking analyses also indicate supplemental feeding during residencies in south-eastern Australian and New Zealand waters, supported by direct visual observations of feeding off Eden at the time of tagging32.The consistency of the SKP feeding ground as a predictable, persistent and high-quality forage resource for HBWs, matches with the WA (stock D) population being identified as mainly “classical feeders” from isotopic analyses50 observed temporal increases in δ15N decoupled from δ13C. Such changes could reflect spatial variability in the δ15N signatures of Antarctic prey, and/or variability of isotopic values at the base of the food web (e.g. pelagic vs sea-ice diatoms54). Alternatively, such changes might indicate shifts to a higher trophic level of Antarctic feeding, either by the prey or by the WA HBWs . The spatial distribution of the WA HBWs tracked at the SKP shows a focus quite far north in the western boundary current (57–60°S). Additionally, a single adult female HBW was resident for more than 1 month at the northern KP (~48°S) with dive data showing very active vertical movement during this period  in fact represents high potential growth rates for 40 mm krill (>3 mm month−1)55. This high-growth habitat contracts farther southward towards the Antarctic continent by January55. The SKP western boundary current may therefore represent one of the locations where winter ice extent (overwintering krill larvae) coincides with high adult potential growth rates during summer, enabling the krill lifecycle to be completed successfully . However the krill net tow data57 necessary to confirm this hypothesis are only typically available from scientific research voyages conducted during mid-summer  and closer to the Antarctic continent59. Similarly, the IWC’s comprehensive circumpolar whale sightings surveys were all conducted south of 60°S61. Since whaling operations favour low ice conditions, spatial distributions drawn from historical whale catches may also bias towards the Antarctic continent in summer. Spatial distributions derived from catches are also confounded by many other conditions . Therefore, to properly test this hypothesis of a northward extension in krill – and hence whale – habitat in this region it would be necessary to conduct research voyages with net tows during late spring and early summer (November to early December).With respect to the spatial extent of the krill biome, an empirical relationship derived for krill growth rate in relation to chlorophyll and temperature has recently been applied across the Southern Ocean62. Globally, the known prey of HBWs include a wide assortment of schooling fish including herring (Clupea spp.) and sand lance (Ammodytes spp.); temperate shrimp, amphipods, and coastal krill ; as well as euphausiid species such as the lipid-rich E. superba53. HBWs are known for the variety and complexity of their feeding behaviours, with capture techniques that include bubble nets, tail slaps, lunges and bottom feeding63. Alternate candidate Antarctic prey items that have higher δ15N signatures might include aggregations of other euphausiids such as Thysanoessa macrura or E. triacantha64. The distribution T. macrura overlaps that of E. superba but may extend to relatively warmer water temperatures; they are also a known prey for whales, and can be very abundant, locally replacing E. superba as the most abundant euphausiid65 and references therein. Other candidate prey might include amphipods (e.g. Themisto gaudichaudii66) or possibly small mesopelagic fishes such as Krefftichthys anderssoni67. Diving data during the HBW residency (ID131140) at the northern Kerguelen plateau are indicative of active foraging in the upper 150 m of the water column  are likely to mix with individuals from eastern Australia (stock E1), particularly via east-to-west movements on the feeding grounds5 . Few Discovery marks were ever deployed in Area III (n = 119) but two Antarctic deployments near 10°E and 60°E, recovered at Madagascar, do indicate significant longitudinal movements42. Satellite tracking from eastern South Africa remains similarly scant, showing truncated migratory journeys in Area III towards the Crozet and Prince Edward Islands, as well as westward of 30°E30. As increasing high latitude genetic sampling  is becoming available, mixed stock analyses are being used to determine the likely population origins of whales across Southern Ocean feeding grounds72. Such an analysis considering stocks C, D and E would be required to describe the population structure on the SKP feeding ground and evaluate the possibility of this being a shared high-quality feeding ground.Southern Hemisphere humpback whale populations are characteristically high in genetic diversity14. It is unknown to what extent prey availability, as a consequence of habitat quality in the Southern Ocean, may provide a constraint on HBW population numbers. Our analysis of movements on the forage grounds, showing significantly higher movement rates by females during both transit and residency, further raises interesting questions regarding the energetic requirements and benefits between the sexes. It is important to note that we did not tag mother-calf pairs which tend to move more slowly41. Hence, the difference in movement rates might be simply explained by size differences with the larger body size of females enabling faster travel relative to males. Alternatively, with high pregnancy rates recently reported in southern hemisphere HBWs73 it is possible these females were pregnant, driving high energetic requirements and hence greater foraging effort. Larger sample sizes (tracking and biopsy) would be useful to resolve these points.Future population assessments considering feeding ground density dependence have also been recommended43. Since then, the interaction of the ACC flow with topography is increasingly understood to influence physical and biological processes at local, regional and large scales74. The new detailed migratory pathways for western Australian humpback whales highlight the southern Kerguelen plateau as a key feeding area. Recent marine survey efforts here have improved our understanding of how the high regional productivity, structured by the interaction of ocean currents and topography, is likely to support a predictable, persistent and rich supply of prey resources for whales. From a management perspective, HBWs and other baleen whale populations are the concern of the IWC14. Alongside, the Convention on the Conservation of Antarctic Marine Living Resources (CAMLR Convention) applies to Antarctic marine living resources in the Convention area, which is divided into nine marine protected area planning domains75. Here, CCAMLR has agreed to establish a representative system of marine protected areas, which seek to address a suite of conservation objectives. Specifically, the foraging migrations of many species of penguins, seals and flying seabirds are considered in the MPA planning and proposal processes, and these data, for example, contributed directly to the Drygalski area of the East Antarctic (and other) MPA proposal(s)76. While this proposed MPA does encompass an important HBW forage area in the southeast, the key forage area associated with the western boundary current clearly extends farther to the north. As we turn towards the future it seems most likely that these two management interests of IWC and CCAMLR will converge in the arena of risk assessments for krill fishing in the Southern Ocean77. In particular, as CCAMLR works to manage harvesting of krill and other species with a precautionary approach this shall be achieved in a way that accounts for consumption needs across predators, including those managed by the IWC, at spatially meaningful scales.Early work proposed the Southern Boundary of the ACC to be of circumpolar ecological importance to the productivity of Southern Ocean ecosystems and the baleen whales which depend upon them78) as humpback whales migrate north and south within coastal fishery areas. Tagging was approved and conducted under the Australian Department of the Environment Cetacean Permit 2014-0005 and the Western Australian Department of Parks and Wildlife (DPAW) permits SF009946 and SF010439. All tagging methods were carried out in accordance with the relevant guidelines and regulations. Full details of tag types and deployment methods are given in Supplementary The tracking data presented here were collected as part of research efforts to reduce fishing gear entanglements in Australian waters , to obtain a regular time sequence of location estimates with reduced uncertainty. The SSM used is a variant of the widely applied model of 80, as described in81 and82 theirAppendix S2. This fast implementation uses the R package TMB83. Associated R and C++ code for processing the Argos data are publicly available as an R package ssmTMB version 0.0.1.9100 (https://github.com/ianjonsen/ssmTMB). The SSM was fit with a 6 h time step providing four location estimates per day . Step lengths (speeds) and turning angles were calculated from these filtered locations and provided to the Hidden Markov Models (HMMs) described below.Due to the irregular timing and errors associated with Argos location data, these were filtered using a state-space model (SSM86). Specifically focussing on the Southern Ocean movements  we investigated 2-state model formulations to discriminate behaviours nominally termed ‘transit’ and ‘resident’. Typically during transit whales are expected to undertake more directed movements, at generally higher speeds of travel and with lower turning rates; the converse occurs during more resident periods, which may occur in areas with higher foraging returns87. However movement may differ between sexes29. To examine for sex-related movement patterns, we investigated four different 2-state HMM configurations: (1) a basic 2-state model, with (2) sex-dependent transition probabilities between states, (3) sex-dependent movement parameters and (4) both sex-dependent transition probabilities and movement parameters. In all models, we used a gamma distribution for step length and a wrapped Cauchy distribution for turning angles, with the model parameters estimated across individuals using a maximum likelihood approach implemented with the R package momentuHMM version 1.4.286. A multiple imputation approach was employed that enables pooled inferences across the HMM analyses to reflect location uncertainty86. Model parameters are calculated as pooled estimates  and 95% confidence intervals (Supplementary For inferring (latent) animal behaviours from movement tracks we applied discrete-time hidden Markov models . HBW catch records south of 36°S within the region 50–150°E  span the pre- and post-war periods 1929–1939 and 1946–1968. West of 50°E, available catch records  span a longer period .Historical catch data for Southern Ocean humpback whales were obtained from the IWChttps://gis.ccamlr.org/home/ccamlrgis); and with reference to the relevant area(s) within the East Antarctic Representative System of Marine Protected Areas (EARSMPA) jointly proposed to CCAMLR by Australia, the European Union and it’s Member States89.We report whale movements within the spatial context of: the relevant IWC Management Areas (Area III/IV boundary is classified at the meridian of longitude 70°E and Area IV/V boundary at 130°E); the Commision for the Conservation of Antarctic Living Marine Resources (CCAMLR) Statistical Areas (Electronic Supplementary Material S1-S4Supplementary S2. Tracking animation.


Blumeria graminis f. sp. hordei is a foliar disease with highly negative impact on yield and grain quality in barley. Thus, breeding for powdery mildew resistance is an important goal and requires constantly the discovery of new sources of natural resistance. Here, we report the high resolution genetic and physical mapping of a dominant race-specific powdery mildew resistance locus, originating from an Ethiopian spring barley accession ‘HOR2573,’ conferring resistance to several modern mildew isolates. High-resolution genetic mapping narrowed down the interval containing the resistance locus to a physical span of 850 kb. Four candidate genes with homology to known disease resistance gene families were identified. The mapped resistance locus coincides with a previously reported resistance locus from Hordeum laevigatum, suggesting allelism at the same locus in two different barley lines. Therefore, we named the newly mapped resistance locus from HOR2573 as MlLa-H. The reported co-segregating and flanking markers may provide new tools for marker-assisted selection of this resistance locus in barley breeding.Powdery mildew caused by  Hordeum vulgare ssp. vulgare L.), is ranked fourth after rice (Oryza sativa L.), wheat (Triticum aestivum L.) and maize (Zea mays L.) in terms of crop production. The prevalent use of barley is as a source of feed and forage for livestock, and as source for food and beverages for humans  is a foliar disease of barley with worldwide importance  with high degree of inbreeding along with the ease of making genetic crosses made barley a favorable biological model for genetic and genomic studies . Consequriticeae .The main objective of the present study was to perform high resolution genetic and physical mapping of a major resistance locus segregating in the recombinant inbred line (RIL) population ‘HOR2573 × Morex.’ This was achieved through applying next generation sequencing-based strategies and taking advantage of the improved barley genomic resources infrastructure.Bgh isolates). The phenotyping of the parental lines was performed through both detached leaf assay (seedling stage) and whole plant assay at field, revealing a strong correlation between resistance data from both assays  – the same as the four Israeli isolates – on HOR2573, thus was selected for the further study. Ninety-five F6-RILs, derived by single-seed-descent (SSD) through five cycles of selfing from the cross of ‘HOR2573 × Morex,’ were used for phenotyping and genetic mapping in three independent experiments. Within each experiment, eight seeds per RIL (F6:7) were sown as eight biological replicates. Plants were phenotyped 14 days after sowing using the second seedling leaf in a detached leaf assay. For this purpose, the plants were grown in trays at 17–20°C under long day conditions (16 h) in the greenhouse. The middle part of the second leaf was cut into two 3 cm long pieces . Detached leaves were placed surfaces upward in four-column plates on water agar (1%) containing benzimidazole (40 mg/l) as senescence inhibitor. In each column of one plate, five RILs were located in randomized block design in combination with both positive (susceptible parent) and negative (resistant parent) controls. The prepared leaf segments were inoculated under the inoculation tower through blowing Bgh conidia (isolate CH4.8) of the sporulating leaves (from four sides) according to 2. The inoculated detached leaves were kept in the incubator growth chamber at 20°C, 60% humidity, 16 h light period and scored macroscopically at 7 days post inoculation (dpi). The disease intensity was rated based on infection area (%) according to An Ethiopian landrace ‘HOR2573,’ resistant to seven highly virulent powdery mildew isolates . These results corroborated the presence of a single major effect dominant locus/gene controlling powdery mildew resistance in the population ‘HOR2573’ × ‘Morex.’The strength and the effect of the identified QTL on phenotypic variation suggested that the powdery mildew resistance from ‘HOR2573’ was most likely controlled by a single major gene. To validate this possibility, disease scoring was re-performed with two qualitative classes (resistant vs. susceptible class) independently from the previous phenotyping scores in order to obtain unbiased results. Based on the qualitative evaluation, 51 out of 95 RILs were consistently scored as resistant whereas 44 RILs were scored as susceptible plants indicating the inheritance of a monogenic Mendelian factor [1:1, ‘Laevigatum’ resistance locus (known as MlLa)  could be anchored to the M238-M252 interval (Laevigatum’) and in ‘HOR2573.’ To point out this coincidence clearly, we propose to name the ‘HOR2573’ mildew resistance locus HMlLa-, indicating that the resistance-conferring putative MlLa allele of this study was derived from the Ethiopian landrace ‘HOR2573.’The long arm of chromosome 2H is known to carry the as MlLa) . To asseinterval , suggestBgh isolate, CH4.8, resulted in the identification of 742 resistant and 259 susceptible plants, consistent with the segregation of a single dominant gene . This segregation pattern was also evaluated individually in each HIF family , verifying the monogenic dominant inheritance of the MlLa-H locus  genes  are located within the genetically delimited target interval. In addition, the structural annotation of the seven genes predicted for the MlLa-H interval was validated through sequence comparisons to putatively orthologous genes from closely related species. This showed that the automated gene annotation for four gene models  had incomplete coding sequences in the automated annotation and thus those were revised accordingly.The attempts of re-annotation of the sequence  and the MlLa-H locus, derived from ‘HOR2573,’ is dominantly inherited, involves a hypersensitive response-like programmed cell death at a microscopic level, thus it is most likely race-specific. This pattern of resistance may suggest the involvement of a gene belonging either to the Nucleotide Binding Site Leucine Rich Repeat (NBS-LLR) or Receptor Like Kinase (RLK) gene families, therefore it was anticipated that the delimited target interval (∼850 kb) of the MlLa-H locus would contain candidate genes belonging to the expected classes of resistance genes. From the seven HC genes, four gene  in the delimited target interval were RGAs, one gene (HORVU2Hr1G126250) belongs to RLK gene family and the rest to the NBS-LLR family  is suggested of having a role in resistance to plant pathogens or plant/pathogen interaction; therefore, they were excluded for any further analysis. As detailed information, HORVU2Hr1G126290 is an uncharacterized protein. Its protein sequence similarity search against the orthologous genes in other species indicated that it is also uncharacterized in other species. In addition, a survey on publicly available transcriptome and gene expression profiling data in barley  showed that it is also highly expressed in developing grains, presenting no role in plant immune responses. The third gene model, HORVU2Hr1G126350 has high homology with SCAR family, being involved in plant cell morphogenesis such as controlling cell division and elongation. Therefore, based on the functional annotation or the transcript evidence, these three genes can be ruled out as candidates.Based on the assigned functional annotation of genes predicted in the barley reference sequence and publicly available transcriptome and gene expression profiling data from different plant tissues in barley , none ofn barley  showed tMlLa-H locus were all promising candidates for the resistance gene. Sequence comparison in resistant (MlLa-H) and susceptible (mlLa-H) genotypes should provide help prioritizing among the four candidate genes. In fact, the presence of a polymorphism correlated to the phenotype in a gene re-sequenced from resistant parent, can make it a good candidate, whereas either the absence of non-synonymous polymorphisms or the emergence of premature stop codons in each RGA in ‘HOR2573’ compared to ‘Morex’ is a clue to reject it as a candidate gene.The four RGAs detected at the HORVU2Hr1G126250) between parental lines revealed 20 SNPs, including 4 synonymous and 16 non-synonymous SNPs, leading to amino acid changes in both LRR and kinase domains (HORVU2Hr1G126380) from resistant parent’s genome ‘HOR2573’ showed that a 42 bp deletion plus a 53 bp insertion occurred in different parts of the second exon, corresponding to the LRR domain. These deletion and insertion led to a premature stop codon  to be typically found in close physical proximity and are the result of tandem duplication events .HORVU2Hr1G126250 was favored as the primary candidate gene for MlLa-H based resistance since it exhibited 4 synonymous and 16 non-synonymous SNPs, leading to amino acid changes in both the LRR and kinase domains in the resistant vs. the susceptible genotypes and was the only of the four candidate genes in ‘HOR2573’ and/or their respective paralogs that was not modified into a pseudogene.From these results MlLa-H, located distally on barley chromosome 2HL. The locus corresponds to the interval of MlLa, derived from H. laevigatum, a previously reported powdery mildew resistance gene based on hypersensitivity response  and physical distance of flanking markers would require screening of an additional 6,000 meioses . The re-sequencing analysis of three out of four potential candidate R genes within the MlLa-H interval from ‘HOR2573,’ the resistant genotype, displayed functional polymorphisms from SNPs to medium and/or large-scale insertions and deletions leading to premature stop codons compared to susceptible parent cv. ‘Morex’  gene family; meaning that it contains an extracellular region, a single membrane spanning domain and an intracellular kinase domain  transgenic complementation through over-expression of the candidate resistance gene in a susceptible genotype  bygenotype , or by  of a resistance gene between resistant and susceptible genotypes, meaning that the candidate gene might be missing from the ‘Morex’ genome. Several studies have underlined the high probability of identification of PAV between genotypes with contrasting phenotypes.Even if Rpp5, a multigene locus in a downy mildew resistant Arabidopsis ecotype, Landsberg erecta (Ler) with a susceptible ecotype, Columbia (Col-0) revealed the presence of ten Rpp5 homologs in the entire Ler haplotype, whereas Rpp5 haplotype in Col-0 consisted of eight homologs. Rpp5 locus contained dynamic gene clusters with capability to adapt fast to a new pathogen variant through modification of recognition regions, implying that these regions have been most likely undergone a diversifying and purifying selection  approach is highly recommended , the race-specific resistance is rather less challenging to incorporate into breeding programs, however, it is often not durable because of rapid changes in the pathogen virulence (MlLa-H locus in barley breeding.To sum up the current study, the reported high resolution mapping and physical delimitation of the resistance locus irulence . CombiniLaevigatum’, provided all relative information for the Laevigatum’ locus. PS provided mapping population and overall supervision of phenotyping. NS designed the study, supervised the experimental work, and contributed to the writing of the manuscript. All authors read, corrected, and approved the manuscript.PH performed the experimental work and performed data analysis, and wrote the manuscript. RZ contributed to data analysis. MM supported data analysis. AH conducted GBS sequencing. RN provided molecular marker information regarding the resistance locus derived from The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Drug withdrawal after treatment day 10 resulted in a relapse in virus titers. These results encourage the use of persistently-infected cultures as a surrogate system in the identification of improved antivirals against flaviviral chronic disease.Chronic viral disease constitutes a major global health problem, with several hundred million people affected and an associated elevated number of deaths. An increasing number of disorders caused by human flaviviruses are related to their capacity to establish a persistent infection. Here we show that Usutu virus (USUV), an emerging zoonotic flavivirus linked to sporadic neurologic disease in humans, can establish a persistent infection in cell culture. Two independent lineages of Vero cells surviving USUV lytic infection were cultured over 82 days (41 cell transfers) without any apparent cytopathology crisis associated. We found elevated titers in the supernatant of these cells, with modest fluctuations during passages but no overall tendency towards increased or decreased infectivity. In addition to full-length genomes, viral RNA isolated from these cells at passage 40 revealed the presence of defective genomes, containing different deletions at the 5’ end. These truncated transcripts were all predicted to encode shorter polyprotein products lacking membrane and envelope structural proteins, and most of non-structural protein 1. Treatment with different broad-range antiviral nucleosides revealed that USUV is sensitive to these compounds in the context of a persistent infection, in agreement with previous observations during lytic infections. The exposure of infected cells to prolonged treatment (10 days) with favipiravir and/or ribavirin resulted in the complete clearance of infectivity in the cellular supernatants (decrease of ~5 log Chronic viral infections constitute a major challenge to global public health, with several hundred million people affected and significant associated fatalities ,3,4,5,6.While most flaviviruses generally trigger apoptotic cell death in vitro, many of them can establish a persistent infection in different cultured cells. Specifically, TBEV can persist in the human embryonic kidney (HEK) 293T cell line for at least 35 weeks without any cytopathic effect crisis observed ,28. ViraFlaviviridae family), there have been developed cell culture systems of persistent infection which bear some degree of resemblance to chronic infection in patients [Cell culture lineages persistently infected with viruses represent tantalizing models in the study of chronic infection in vitro and the characterization of antiviral drugs ,32. Mostpatients ,34. TissIn this study, we have investigated the capacity of Usutu virus (USUV) to establish persistence in African green monkey kidney epithelial cells (Vero cells). These cells are permissive to most human flaviviruses, and are generally employed in their propagation and biological characterization. USUV is an emerging threat, rapidly spreading in different wild and captive birds in Europe, and causing large mortality in some species, e.g. blackbirds ,36. AlthHere, we have isolated two independent lines of Vero cells that became persistently infected after surviving an apparently lytic infection with USUV. The advantage of including two cellular lineages is that those biological features reproduced in both lines may be more relevant to understanding viral persistence. We showed that persistently-infected cells were successfully maintained for 82 days (41 passages), with viral infectivity positively detected in all the cellular supernatants. The genetic analysis of viral RNA extracted from the cells after 40 passages revealed the presence of both full-length and defective viral genomes in each cell line. Different in-frame deletions (>2 Kb) were identified, all of them located at the 5’ end of the viral RNA. These truncated genomes are predicted to encode shorter viral polyproteins lacking partially or entirely several structural proteins (membrane (M), its precursor (PrM), and envelope (Env) proteins) and non-structural protein 1 (NS1).To calibrate the efficacy of this cell culture model in the study of antiviral compounds, we have used three broad-range nucleoside analogues that we previously examined during a lytic infection . In our 2.To this study we used an USUV strain isolated from infected birds in Austria (2001) and provided by Giovanni Savini from Istituto G. Caporale, Italy ,47. The 6 Vero cells in 35 mm culture dishes, and incubated them overnight at 37 °C in the presence of 5% CO2. We then removed the cellular supernatant and inoculated USUV at a multiplicity of infection (MOI) of 0.01. Extensive cytopathic effect was observed at 48 h post-infection although we found that ~20% of the cells remained attached to the plate even at later post-infection times (6 cells to a new 75 cm2 flask in each passage.For the establishment of persistently-infected cultures we seeded 1 × 10on times . At 48 (50) assays as previously described [4 Vero cells in 60 µL of media containing 5% FBS was added. On the following day, 100 µL of 10-fold serial dilutions of each viral sample, in media containing 1% FBS, was applied to each well, reaching a final volume of 160 µL. The virus titers were determined by scoring the number of infected wells showing apparent cytopathic effect at day 5 post-infection, and using the Reed and Muench method [To analyze virus titers, cellular supernatants were collected from persistently-infected cells (at 48 h post-seeding) before each cell passage. The presence of infectious virus in these supernatants was determined by 50% tissue culture infectious dose (TCIDescribed . Brieflyh method .50) for each drug treatment, we seeded 2 × 104 cells per well in a 96-well plate. On the following day, cell supernatants were removed and 100 µL of 1% FBS complete media containing 5-fluorouracil , ribavirin (1-(β-d-Ribofuranosyl)-1H-1,2,4-triazole-3-carboxamide, Sigma-Aldrich), favipiravir  or a combination of ribavirin and favipiravir at concentrations ranging from 25 to 2000 µM was added. Cells were incubated at 37 °C and in the presence of 5% CO2, and supernatants containing virus were collected at different time points for subsequent analyses.To determine the 50% inhibitory concentration , which accounts for living active cells, following the indications provided by the manufacturer.Cell toxicity assays were performed on 96-well plates using the same drugs and concentrations abovementioned for IC5 cells per well in a 24-well plate. On the following day, cell culture supernatants were removed and 1 ml of 1% FBS complete media containing 2000 µM ribavirin, favipiravir, or a combination of ribavirin and favipiravir were added. Cells were incubated at 37 °C and in the presence of 5% CO2.To examine the effect of antiviral nucleosides upon persistent USUV during prolonged treatment, we seeded 1 × 10Viral RNA was extracted from either 100 µL of cell supernatants or directly from whole cell monolayers grown in 24-well plates, using GeneJET RNA Purification Kit (ThermoFisher). To amplify the USUV viral RNA molecules, we followed a two-step RT-PCR amplification procedure. Briefly, 4 µL of purified RNA extracted from whole cell monolayers were reverse-transcribed in a final volume of 20 µL using SuperScriptIII , as indicated by the manufacturer. Three microliters of cDNA were then PCR amplified using AccuPrime Taq DNA Polymerase High Fidelity as indicated by the provider (Thermofisher). To generate overlapping amplicons covering the entire USUV genome, we used primers spanning genomic positions: 1 to 55 (sense) and 7950 to 7929; 4218 to 4189; 3359 to 3335 or 2673 to 2653 (antisense); 818 to 842 (sense) and 3359 to 3335 (antisense); 2976 to 3009 (sense) and 7950 to 7929 (antisense); and 6841 to 6864 (sense) and 11066 to 11016 (antisense). PCR products were directly extracted with a QIAquick PCR Purification Kit  or individual PCR bands on an agarose gel were purified using the PureLink Quick Gel Extraction Kit . The resulting PCR products were Sanger sequenced . Full genome sequences of our stock virus (passage 0) or USUV adapted to persistence (S and V cells at passage 40) were compared to the reference strain (Genbank ID: AY453411) using the CLC Main Workbench program .To detect total viral RNA in the sample (including both standard and defective genomes), we used a protocol previously described ,50. Brie9 viral RNA molecules/µL in 100 ng/µL yeast RNA. This sample was serially diluted 1:10 in yeast RNA to generate aliquots containing 108–100 molecules/µL. Two independent sets of standards were prepared for each qPCR plate.To obtain a standard curve of known amounts of viral genomes, samples were prepared with USUV RNA extracted from lytically-infected cells. To quantify the number of viral RNA molecules present in the extract we used known amounts of USUV cDNA  and the FAM–TAMRA method abovementioned. Once viral genome concentration was determined, the reference USUV RNA used to prepare the standard curve was distributed in aliquots of 5–10 µL in low-biding tubes and stored at −80 °C. For each qPCR experiment we used fresh aliquots (only frozen–thawed once) and discarded them after the experiment. The standard curve samples were prepared on the same day as the qPCR assay by diluting our reference USUV RNA to a final concentration of 10Statistical significance was determined using GraphPad Prism 8  as specified in each corresponding figure legend.To establish persistently-infected cultures we inoculated USUV onto two monolayers of Vero cells that are subsequently referred as V and S lines . At 48 h50 assay) and viral RNA (qPCR) in the cellular supernatants. Both cell lines showed elevated titers along the whole passage history, suggesting that infectious USUV is continuously shed by these cells to the extracellular environments. Notably, cellular supernatants collected from persistently-infected cells (which showed no cytopathology) caused normal cytopathic effects during infection on regular Vero cell cultures, permitting virus titration as normal. This observation may be indicative of V and S cells becoming resistant to lytic infection. Viral titers fluctuated between 105 and 108 TCID50/mL although no overall tendency to higher or lower virus yields were observed during the passages . USUV specific infectivity, which measures the ratio between infectious virus particles and viral genomes, was decreasing along passages . Different PCR amplicons covering the USUV 5’-end genome revealed the presence of large deletions in both V and S cells . In V ceTo quantify the relative amount of full-length genomic RNA to total viral RNA (including both standard and defective genomes) we used two different qPCR quantification methods specifically targeting two genomic regions: Env and NS5 . The qPCThe quantitative analysis of viral RNA in cellular supernatants also suggests the release of particles containing truncated genomes to the extracellular environment, as lower proportions of standard USUV genomes are detected in S and V cells than in Vero cells infected with wild type USUV . The anaFull-length genome sequencing of viral RNA isolated at passage 40 revealed the presence of four repeated nucleotide substitutions in both V and S cell lineages. These changes included two silent mutations in the Env and M coding regions, and two non-synonymous mutations in NS4A and NS4B-coding regions, leading to amino acid replacements E45N and T92M, respectively . Another50 values obtained for each drug were similar in different cellular contexts but slightly lower for persistently-infected cultures. The selectivity indexes for these compounds were relatively high for all these drugs, except for Vero cells treated with FU which showed elevated toxicity. We decided to investigate if a combination of FAV and RBV (F + R) could lead to improved antiviral activities  against persistent USUV. We have recently demonstrated that USUV is sensitive to all these drugs during a lytic infection . In our tivities D,H. We onfection .To investigate whether prolonged exposure to a cocktail of F + R could be effective in curing persistently-infected cells, we treated V and S cells for 6 consecutive days in the presence of a concentration of 2000 µM for each drug. We initially tested the antiviral activity of an F + R combination for 6 days on both V and S cells . By day To further investigate the dynamics of virus extinction by antiviral nucleosides in persistently-infected cells, and whether longer exposure to these drugs could lead to completely curing infection, we set up a larger experiment to analyze virus titers and RNA levels at different time points . Owing tThis loss in infectivity was also accompanied by dramatic decreases in the viral RNA levels. By day 10, viral RNA was barely detectable in FAV or RBV-treated cells, and it was completely absent in F + R series, suggesting the complete extinction of USUV in the cellular supernatant C,D. The To examine whether S p39 cells treated for 10 days had been completely cured of the infection, we cultured these monolayers for three additional days in the absence of drugs . We foun10 lower than in mock-treated cells, in striking contrast with the large decreases in virus titers and RNA levels observed in the supernatant of the same cells (~5-log10 decrease). To rule out that this disparity may be due to a distinct sensitivity to drugs in standard and defective genomes, we used both qPCR techniques abovementioned to detect either Env- or NS5-coding regions. We confirmed that the intracellular decrease of standard full-length viral genomes was similar to that observed for total viral RNA, which is indicative of a similar susceptibility to drugs in both truncated and standard genomes , infectious viral genomes may be replicating intracellularly and escaping treatment. To investigate this possibility we analyzed the presence of viral RNA in whole cell RNA extracts isolated at different time points A. We con compare A,B. ThusAs a consequence of diverse socio-economic and environmental changes, flaviviruses transmitted by arthropods are a growing source of public health concern. In the last few years, new emerging pathogens causing human disorders with an overall increase in the incidence of flaviviral disease have been documented ,44,54,55The use of cell culture systems has been proposed as a conceivable surrogate approach to characterize the determinants that regulate a persistent infection in the host. In particular, cell culture systems of infection have been developed for HCV, a pathogen genetically related to flaviviruses transmitted by vectors ,32. HCV AKT2 and ERBB2, were overexpressed in persistently infected cells while proapoptotic genes, such as Bad and beta interferon-1, were downregulated [The use of cell culture lines can help identify those host genes that are distinctly expressed during persistence relative to the acute phase of a viral infection. This information can be relevant to unraveling the networks activated or inhibited in cells surviving infection. The identification of these host factors can be exploited in the design of antiviral therapies based on drugs targeting them. Evidence supporting the use of in vitro models in the characterization of the cellular and viral determinants modulating persistence has been obtained for TBEV . These pegulated .Despite the lack of knowledge regarding the mechanism by which USUV establishes persistence, we anticipate that defective viral genomes (DVGs), containing truncations of variable length at the 5’ end, may be playing a major role in this process, in agreement with several lines of evidence ,7. All tIndirect evidence from nucleoside drug experiments described above underpins the idea of DVGs having a protective role for the host cell. We found that antiviral treatment followed by drug removal generally led to increased cell death associated with the relapse in infectivity D. We posWe hypothesize that this cell culture system for persistent USUV can be instrumental in the identification of effective therapeutics in the control of infection. In recent years, USUV has caused a modest but growing number of cases of human disease, mainly affecting European countries ,43,44,64We have previously examined the efficacy of these drugs against USUV during lytic infections, and established an association between the antiviral activities observed and increased virus mutation frequencies . The useFull genome sequence analysis of USUV has identified the presence of several non-synonymous mutations, most of them accumulated in the NS4A and NS4B coding regions. Both NS4A and NS4B proteins interact with each other in the infected cell, and the determinants of this interaction have been characterized for dengue virus . The resFlavivirus NS4A and NS4B proteins are essential to the viral life cycle. Both viral products are directly implicated in membrane rearrangements of the endoplasmic reticulum (ER) needed for the formation of the replication complex, and the induction of autophagic pathways that prevent death of the infected cell ,73,74,75We posit that some of those genetic alterations identified in persistent USUV are provoking its attenuation in Vero cells, thus facilitating cell survival to infection. We now aim to investigate whether these changes are leading to USUV infectivity losses not only in mammalian but also in other avian and insect cell lines. These prospective studies can help reveal the viral determinants that modulate virulence in vertebrate and invertebrate hosts.The development of cell culture systems based in persistent flavivirus infection can be instrumental to better understanding the intracellular rearrangements implicated in chronic viral disease. Cellular models of persistent infection can also provide better surrogates for in vitro systems to examine the efficacy of antiviral compounds in the treatment of chronic infection. We have validated our model using old-known antivirals which exhibited sustained activity and suppressed detectable viral infectivity in the cellular supernatants during prolonged periods, although virus relapse occurred when drugs were removed. These results encourage the use of this model of infection for the identification of improved therapeutic drugs against the flaviviruses.


The anesthetic management of an obese patient can be challenging because of the altered anatomy and physiology associated with obesity. In this article, I review the recent medical literature and highlight some of the controversies in the airway management and drug dosing of morbidly obese patients. This is especially true for anesthesiologists, since the obese patient can present challenges in many areas of their perioperative management.The alarming worldwide increase in obesity, particularly extreme or “morbid obesity” , were greater in obese patients compared to lean patients. However, there was no increase in the number of intubation attempts as BMI increased: by this definition, difficult intubation was no more likely in a morbidly obese patient than in a patient who was only moderately obese3.It is still unclear whether video-assisted laryngoscopy (VAL) rather than conventional DL should be the routine approach to tracheal intubation for obese patients. Many believe that VAL reduces the number of failed intubation attempts by improving the glottic view while also reducing laryngeal/airway trauma. However, a recent meta-analysis failed to demonstrate that VAL, when compared to conventional DL, actually decreased the number of intubation attempts or the incidence of hypoxia or respiratory complications. In addition, VAL did not shorten the time required for successful intubation in adult subjects2) drops to potentially dangerous levels, is extremely short (SAP of 2–3 minutes) compared to normal-weight patients (SAP of 8–10 minutes). Therefore, an airway must be secured rapidly and/or the duration of SAP must be increased to allow additional time for successful intubation of the trachea.Airway management remains a challenge for all obese patients because their safe apnea period (SAP), that is the time between muscle paralysis and apnea until oxyhemoglobin saturation (SpO2) while producing approximately 200 mL/minute of carbon dioxide (CO2). Most of the CO2 remains in the blood, resulting in a progressive respiratory acidosis, but the O2 is consumed from the alveoli with a loss of lung volume. The resulting pressure differential causes mass movement of gas from the upper airways into the alveoli. Therefore, delivery of a high concentration of O2 at any airway level  can increase alveolar O2 stores and delay or prevent desaturation.Recently, there has been increased interest in apneic or “diffusion” oxygenation to increase SAP. During apnea, the body continues to consume approximately 250 mL/minute of oxygen . THRIVE combines the benefits of apneic oxygenation with continuous positive airway pressure (CPAP) and gas exchange through flow-dependent dead-space flushing. THRIVE using 70 L/minute of humidified O2 was begun as an adjunct to routine pre-oxygenation and then continued both during intravenous induction of anesthesia and following paralysis. Apnea time was measured from the initiation of neuromuscular blockade until jet ventilation or positive-pressure ventilation was instituted and/or resumption of spontaneous ventilation occurred. During apnea, upper airway patency was maintained with jaw-thrust. The median apnea time for all patients in this study was 14 minutes, and no patient experienced arterial desaturation (SpO2 of less than 90%)4.Apnea time of patients with difficult airways, including several obese patients undergoing general anesthesia for upper airway operations, was extended with continuous delivery of O2 at a rate of 6 L/minute for 3 minutes with CPAP (15 cm H2O), while another group received THRIVE at 30 L/minute for 3 minutes. Following paralysis, “apneic” ventilation continued with 10 L O2/minute with CPAP at 15 cm H2O in the first group. The THRIVE group received 60 L O2/minute. The endpoint was desaturation to an SpO2 of less than 90% and/or a maximum apnea time of 12 minutes without desaturation. Both treatments were equally effective in prolonging SAP without desaturation for up to 12 minutes. The CPAP group had an added advantage of lower PaCO2 with less acidosis5. The use of high-flow nasal O2 during pre-oxygenation and then continued during apnea can also prevent hypoxia before and during intubation attempts by extending SAP6.A study compared arterial oxygenation during apnea following different pre-oxygenation techniques. One group was pre-oxygenated by face mask with 100% O2) were randomly assigned to routine pre-oxygenation or pre-oxygenation plus “buccal” oxygenation. Buccal O2 was administered via a modified 3.5 mm Ring-Adair-Elwyn (RAE) tracheal tube placed inside the patient’s cheek. Patients receiving buccal oxygenation were much less likely to exhibit an SpO2 of less than 95% during 750 seconds of apnea. Median apnea times with an SpO2 of 95% or more were prolonged in the buccal oxygenation group compared to the non-buccal oxygenation group7. Thus, clinically important prolongation of SAP in obese patients can be achieved by delivering buccal O2 during and after the induction of anesthesia. This approach to apneic oxygenation via an oral route requires lower O2 flows and less equipment than THRIVE while improving management of the difficult airway and prolonging SAP.In another study, obese patients  with the operating room table in the reverse Trendelenburg position. Pre-oxygenation by face mask should be instituted, but, rather than normal tidal volume inspiration, the morbidly obese patient should be instructed to take deep vital capacity breaths. Some form of apneic oxygenation should also be considered to extend SAP. It is important to emphasize that apneic oxygenation by any route cannot compensate for ineffective pre-oxygenation, and the patient’s upper airway must remain patent for O2 or more) to receive a propofol infusion (100 mg/kg/hour) for induction of anesthesia based on their TBW or lean body weight (LBW). Control subjects (BMI 25 kg/m2 or less) also received a propofol infusion (100 mg/kg/hour) based on actual (TBW) weight. All subjects were given a 20 mL syringe filled with saline to hold between the thumb and index finger of the hand opposite the intravenous drip and were told to not drop it. During propofol infusion, the moment the syringe was dropped was used as the marker for loss of consciousness (LOC), at which point the propofol infusion was discontinued. The total propofol dose (mg/kg) required for syringe drop and the time to LOC were similar between control normal-weight subjects and morbidly obese subjects given propofol based on LBW. Morbidly obese subjects receiving propofol based on TBW received significantly larger propofol doses and had significantly shorter times to LOC8. These findings suggested that LBW is the appropriate dosing scalar for propofol to achieve LOC at induction of anesthesia in morbidly obese patients.Obesity has significant effects on the metabolism and pharmacokinetic profiles of most anesthetic agents. Propofol is the drug most frequently used for the induction of general anesthesia, but the appropriate dosing in obese patients remains controversial. Although bolus dose recommendations based on actual or total body weight (TBW) are valid in normal-weight patients, large doses based on TBW in morbidly obese patients can be dangerous. A prospective study randomized morbidly obese subjects (BMI 40 kg/m2 or more) were randomized to either a non-scalar method utilizing a brain function monitoring device  or a scalar method based on LBW. Anesthesia was induced with either a propofol infusion of 100 mg/kg/hour to an initial target end-point (BIS = 50) or until a pre-calculated dose of 2.6 mg/kg based on calculated LBW was administered. Induction was assessed using the Observer’s Assessment Alertness/Sedation (OAA/S) scale, where a lack of response to a painful trapezius squeeze signified a score of 0. If an OAA/S score of 0 was not achieved, the propofol infusion was continued until the OAA/S score reached 0. The induction dose of propofol based on the BIS index end-point was different from the induction dose based on calculated LBW. The majority of the patients in the LBW group required additional propofol to achieve an OAA/S score of 0. Based on these findings, the authors questioned how useful LBW is as a scalar to accurately estimate the correct dose of propofol to be administered to morbidly obese patients9.A more recent study challenged these recommendations. Morbidly obese patients  undergoing pre-bariatric surgical outpatient esophagogastroduodenoscopy (EGD) with non-obese control patients (BMI 25 kg/m2 or less) undergoing diagnostic EGD. The obese group had a high incidence of sleep apnea , experienced more SpO2 desaturations , and received more chin lift maneuvers  than did the lean group. Yet, despite these differences, the authors concluded that with appropriate training of endoscopy personnel, propofol sedation without anesthesia personnel being present was still a safe method of sedation in severely obese patients undergoing outpatient upper endoscopy11. The high incidence of “desaturation” and the frequent need for chin lift presumably to open the patients’ upper airways suggest a different conclusion: the potential for serious airway complications is always present with propofol sedation, and anesthesia personnel should be managing these high-risk obese patients.Intravenous propofol is an effective method of sedation for patients undergoing procedures requiring sedation outside the operating room. Its use by non-anesthesia professionals has been advocated. A retrospective cohort study compared propofol sedation of obese patients . The manufacturer recommends that the dose of sugammadex be based on actual body weight and the level of neuromuscular blockade.2 or more (obese) and less than 30 kg/m2 (non-obese). Sugammadex was administered based on actual weight. No clinically relevant correlation was observed between BMI and time to recovery. At high doses of sugammadex based on TBW, there was rapid recovery from neuromuscular blockade in both obese and non-obese patients12.A meta-analysis of 27 trials evaluated recovery times following sugammadex reversal in patients with BMIs of 30 kg/mFor moderate neuromuscular blockade, defined as recovery of two or more twitches in response to train-of-four stimulation, a dose of 2 mg/kg TBW is recommended by the manufacturer, irrespective of actual weight. Several studies have demonstrated that this amount is both unnecessary and expensive in morbidly obese patients.13.Bariatric surgical patients received sugammadex based on either TBW or ideal body weight (IBW). The mean dose of sugammadex in the IBW group was 4 mg/kg based on IBW plus 35%. Time to complete reversal of neuromuscular blockade was not significantly different between the two groups, even though sugammadex doses were significantly lower in the IBW group14. A single vial of sugammadex contains 200 mg of the drug, which is considered adequate for the reversal of neuromuscular blockade for obese patients. Since morbidly obese patients are at risk for hypoventilation and upper airway obstruction following tracheal extubation, neuromuscular blockade monitoring remains essential to detect residual neuromuscular blockade or recurarization.Even lower doses of sugammadex have been used successfully in morbidly obese patients. A dose of sugammadex of 4 mg/kg based on IBW only allowed suitable reversal of deep rocuronium-induced neuromuscular blockadeThe anesthetic management of the morbidly obese patient continues to evolve and change, and many controversies remain. Techniques that may work well for a normal-weight patient may be inappropriate and even unsafe for an obese patient. Published studies, based on the experiences of others, help to guide anesthesiologists in the care of these patients.