The lipid composition of hypodermal membranes from the XXXX ( @entity11061 ) changes during the molt cycle and alters hypodermal @entity460 permeability.

@entity3952 @entity11061 @entity460 @entity1718 @entity165
Crustaceans are covered by a cuticle that does not grow. In order for an individual to grow, the cuticle must periodically be shed (ecdysis). Replacement of the old cuticle with a new one depends on processes that require precise timing and control, yet the nature and location of these controls remain unclear. A candidate site for them is within the hypodermal microvilli. These cellular structures extend through pore canals deep into the acellular cuticular matrix. Changes in the lipid composition of hypodermal microvilli could modulate water and ion fluxes and enzyme activities during critical stages of the molt cycle; however, the lipid composition of these structures has not been assessed during the molt cycle. Data presented here show that phospholipids isolated from hypodermal microvilli of @entity11061 initially have elevated levels of n-6 @entity1718 that decline steadily beginning just after ecdysis. Experiments with liposomes reveal that n-6 @entity1718 decrease the @entity460 permeability of membranes, suggesting that the initially elevated levels in the cuticle may function to reduce @entity460 flux from the cuticle into the hypodermis. In addition, the ratio of @entity165 to phospholipid and the proportion of @entity3952 in membrane phospholipids are maximal at 6 h post-ecdysis. It is known that changes in @entity165 and @entity3952 content alter membrane permeability to water. It is, therefore possible that water flux through hypodermal membranes is also modulated in the early post-molt cuticle. Changes in microvillar lipid composition might serve importantly to control biomineralization in the post-ecdysal cuticle.
