Dissociation of V1 from V0 occurs during molting in caterpillars and during glucose deprivation in yeast , and indicates inactivation of the protein. Saline water reared larvae: V ATPase and Na K ATPase localization When anopheline larvae were reared in saline water, we observed a shift in Na K ATPase localization to the DAR cells . Whereas in An. albimanus this shift was drastic, accompanied by a decrease in Na K ATPase in the non DAR cells, in An. gambiae Na K ATPase was present in both DAR and non DAR cells, suggesting an intermediate condition. In An. gambiae we also noted a marked reduction in the overall Na K ATPase signal as well as a noticeable increase in VATPase signal in the cytoplasm of all rectal cells. This may indicate a breakdown in the iontransporting functions of the rectal cells. As an obligate freshwater larva, An. gambiae lacks the ability to secrete a hyperosmotic urine and in fact cannot survive more than 24 hours when acclimated to 60% ASW. It is possible that the stress incurred by exposure to saline water causes a breakdown in the cellular components of the ion regulatory organs, which would lead to death.
In saline tolerant larvae such as An. albimanus, we did not observe any decrease in Na K ATPase protein signal or any indications of protein degradation. An. albimanus larvae can survive to compound library screening pupation in up to 75% ASW, with about 35% of the 1st instar larvae reaching pupation . The dramatic shift in Na K ATPase appears to disrupt the physiological coupling between Na K ATPase and V ATPase which we predict to be responsible for Na resorption in freshwater conditions. This shift renders the non DAR cells similar in protein localization to the PR of the saline tolerant culicine Oc. taeniorhynchus, and is likely to result in the ability of the non DAR cells of An. albimanus to secrete a hyper osmotic urine in a fashion similar to Oc. taeniorhynchus as discussed below. Oc. taeniorhynchus larvae are highly saline tolerant, able to survive up to 300% ASW by regulating their hemolymph to maintain a constant osmolarity of about 350 mOsmL 1 .
The rectum of this species differs from that of the freshwater Veliparib Ae. aegypti by the presence of an additional segment which secretes a hyperosmotic urine and rids the hemolymph of excess ions from a saline environment. The PR of Oc. taeniorhynchus expressed high levels of V ATPase on the apical lamellae but did not appear to express Na K ATPase. The presence of an apical V ATPase is supported by ultrastructural studies of other saline tolerant culicines which described a particulate coat made up of spherical subunits on the cytoplasmic surface of the apical lamellae , indicating V ATPase containing portasomes.