Seasonal Adaptations of the Hypothalamo-Neurohypophyseal System of the Arabian One-Humped Camel

The “ship of the desert”, the one-humped Arabian camel (Camelus dromedarius), has a remarkable capacity to survive in conditions of extreme heat without needing to drink water. One of the ways that this is achieved is through the actions of the antidiuretic hormone vasopressin (AVP) and the natriuretic hormone oxytocin (OXT), both of which are made in a specialised part of the brain called the hypothalamo-neurohypophyseal system (HNS), but exert their effects at the level of the kidney to, respectively, provoke water conservation and salt excretion. Interestingly, our electron microscopy studies have shown that the ultrastructure of the camel HNS changes according to season, suggesting that in the arid conditions of summer the dromedary’s HNS is in a state of permanent activation, in preparation for the likely prospect of water deprivation. We have sequenced the genome of an Algerian camel called “Jamal”; his genome consists of 2.09Mb (210,368 contigs, with 115,325 >1000nt) from which we predicted 64,989 gene models. Based on this unique resource, we have carried out a preliminary RNAseq analysis of the camel HNS in summer and winter. Interestingly, amongst the 435 genes found to be significantly differentially regulated (edgeR p value <0.05) is OXT (winter 4.3 fold greater than summer). Further, we have shown that the AVP gene is subject to unique camel specific alternative splicing events that may result in the production of novel peptides. Ongoing peptidomic studies are relating these findings to the elaboration of hormones by the camel HNS in response to season.