Project description:To investigate the central control of water homeostasis in the dromedary camel, we have performed transcriptomic studies on the supraoptic nucleus samples from camels under control (water ad libitum) and dehydrated (water deprivation for 20 days) conditions by RNA sequencing. We have identified genes that change in expression in response to hyperosmotic challenge and transcriptomic response networks that might be essential for adaptations of camel to live and thrive in aird desert environment.
Project description: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. Based on our camel genome sequence, we have carried out an RNAseq analysis of the camel HNS in summer and winter.
Project description:Peptides were qualitatively characterized in supraoptic nuclei (SON)of dromedary camels by liquid chromatography-mass spectrometry/mass spectrometry. Samples collected in winter and summer were analyzed separately. Qualitative seasonal differences were noted. The presence of the PMCH hormone by detection of a single peptide, Neuropeptide-glutamic acid-isoleucine (EIGDEENSAKFPI-amide), only in winter SON. SCG1- and SCG2- derived peptides were detected in both seasons, but more peptides identified in winter than summer for either of the proteins. Peptides from SCG3 were detected only in winter SON samples. We found evidence of alternative splicing of the tachykinin precursor 1 in dromedary between seasons. In summer, we detected neurokinin A (isoforms 2,4, and 6) as well as peptide DADSSVEKQVALLKALYGLGQISHKMAYE confirming prohormone variant without neurokinin A (dromedary isoforms 3 and 7), while in winter SON we detected peptides supporting prohormone variants with neurokinin A (isoforms 2, 4, 6). Substance P was detected only in winter samples. The MS data supported some of our transcriptomics results.
Project description:The one-humped Arabian camel (Camelus dromedarius) is the most important livestock animal in arid and semi-arid regions and continues to provide basic necessities to millions of people. In the current context of global warming, there is renewed interest in the adaptive mechanisms that enable camelids to survive in arid conditions. Recent investigations described genomic signatures that revealed evolutionary adaptations to desert environments. We now present a comprehensive catalogue of the transcriptomes and proteomes of the dromedary kidney and describe how the gene expression profiles of Differentially Expressed Genes (DEGs) are modulated as a consequence of chronic dehydration and subsequent acute rehydration. We performed RNAseq and quantification of peptides in samples from 15 dromedaries (5 controls, 5 dehydrated and 5 rehydrated). Gene Ontology analyses suggested an enrichment of the cholesterol biosynthetic process and an overrepresentation of categories related to ion transmembrane transport in the camel kidney, and RTN analyses confirmed alterations in the transcriptional machinery involved in cholesterol synthesis. These data were validated by RT-qPCR. Based on our hypothesis of a role for cholesterol during dehydration, we identified DEGs with roles in the countercurrent multiplication process which are affected by changes in the level of cholesterol. Thus, we further validated differentially expressed genes with known roles in water conservation which are affected by changes in cholesterol levels. Our datasets suggest that suppression of cholesterol biosynthesis may facilitate water retention in the kidney by indirectly facilitating the AQP2-mediated water reabsorption.
Project description:The one-humped Arabian camel (Camelus dromedarius) is the most important livestock animal in arid and semi-arid regions and continues to provide basic necessities to millions of people. In the current context of global warming, there is renewed interest in the adaptive mechanisms that enable camelids to survive in arid conditions. Recent investigations described genomic signatures that revealed evolutionary adaptations to desert environments. We now present a comprehensive catalogue of the transcriptomes and proteomes of the dromedary kidney and describe how the gene expression profiles of Differentially Expressed Genes (DEGs) are modulated as a consequence of chronic dehydration and subsequent acute rehydration. We performed RNAseq and quantification of peptides in samples from 15 dromedaries (5 controls, 5 dehydrated and 5 rehydrated). Gene Ontology analyses suggested an enrichment of the cholesterol biosynthetic process and an overrepresentation of categories related to “ion transmembrane transport” in the camel kidney, and RTN analyses confirmed alterations in the transcriptional machinery involved in cholesterol synthesis. These data were validated by RT-qPCR. Based on our hypothesis of a role for cholesterol during dehydration, we identified DEGs with roles in the countercurrent multiplication process which are affected by changes in the level of cholesterol. Thus, we further validated 3 genes coding for ion transporting proteins (KCNJ8, SLC9A7 and ATP1B3) and AQP2, which were upregulated during dehydration. Our datasets suggest that suppression of cholesterol biosynthesis may facilitate water retention in the kidney of the dromedary by indirectly enhancing the osmotic gradient along the medullary interstitium and the AQP2-mediated water reabsorption.