Seasonal variation of @entity3624 oxidoreductase activity in the digestive gland cells of the mussel XXXX : a biochemical, histochemical and immunochemical study.

@entity3042 @entity3624 @entity26 @entity20984 @entity35
The activity and the tissue distribution of the @entity26 radical producing enzyme @entity3624 oxidoreductase (XOR) were measured in the digestive gland of the common marine mussel @entity20984 Lmk along an annual cycle. No @entity3624 oxidase (XOX) activity could be measured, the enzyme only displaying @entity3624 dehydrogenase (XDH) activity in all the cases. This is interpreted as a mechanism to avoid the harmful effects of the @entity26 radicals that would be produced by XOX during periods following anoxic conditions at low tide. The highest XDH activities coincided with the late spring/early summer months, the activity maxima being recorded from May to July. Histochemically XOR activity was very pronounced in duct and stomach epithelial cells as well as in the surrounding connective tissue and hemolymph vessels, the activity increasing towards the summer months. These seasonal variations in XDH or XOR activities are possibly linked to hormonal changes governing the reproductive cycle and to changes in food availability. The localization of the protein in the connective tissue lining the hemolymph vessels was confirmed immunohistochemically using a polyclonal antibody against @entity35 liver protein that cross-reacted specifically with a polypeptide of 150 kDa of molecular mass in homogenates of the digestive gland. This polypeptide was linked to cytosolic fractions isolated by differential centrifugation from mussel digestive glands. In paraffin sections the antibody labeled the digestive cells of digestive tubules, as well as the connective tissue surrounding the hemolymph vessels, gonadal follicles, digestive epithelia and certain protozoan parasites. Taken together our results suggest that in the digestive gland of bivalve molluscs XOR is involved in the metabolism of @entity3042 and in the scavenging of @entity26 free radicals.
