Aquaporin and aquaglyceroporin genes have different expression levels in the digestive tract and Malpighian tubules of honey bee nurses and foragers (Apis mellifera)

The major intrinsic protein (MIP) is vital to a fast water transport through cellular membranes. Many studies about the insect MIP family, such as aquaporins and aquaglyceroporins, have been published so far, but research on honey bee (Apis mellifera) aquaporins is still poor. Five putative MIPs have been identified for the honey bee. We investigated the expression of one aquaporin and two aquaglyceroporins in the digestive tract and Malpighian tubules of nurses and foragers of A. mellifera. Honey bees were collected and dissected for mRNA extraction followed by cDNA synthesis. qPCR was performed with primers for Am_Eglp 1, Am_PRIP and Am_Eglp 2, and the reference gene RpL32. The expression profile varied depending on the evaluated organ and honey bee task. The crop of nurse bees showed higher transcript quantities for the three tested genes. In the midgut of nurse workers, Am_PRIP and Am_Eglp 2 were highly expressed, while Am_Eglp 1 had similar expression level comparing nurses and foragers. In the ileum and rectum, the tested MIPs are highly expressed in forager workers. In Malpighian tubules, Am_Eglp 1 was higher expressed in nurses, whereas Am_PRIP and Am_Eglp 2 had similar quantities in nurse and foragers. Our findings provide new data for future studies on the role of aquaporin and aquaglyceroporin in the digestion and osmoregulation of A. mellifera.