Project description:Camelids are capable of producing both conventional tetrameric antibodies (Abs) and dimeric heavy-chain antibodies (HCAbs). While B cells generating these two types of Abs exhibit distinct B-cell receptors (BCRs), it remains unclear whether these two B cell populations differ in their phenotypes and developmental processes. Here, we collected eight PBMC samples before and after immunization from four Bactrian camels and conducted single-cell 5’ RNA sequencing. We characterized the functional subtypes and differentiation trajectories of circulating B cells in camels, including native B cells, memory B cells, intermediate B cells, atypical B cells, and plasma cells. Additionally, we reconstructed single-cell BCR sequences and revealed the IGHV and IGHC gene types. We found that B cells with variable genes of HACbs (VHH) were widely present in various functional subtypes and showed highly overlapping differentiation trajectories to B cells with variable genes of conventional Abs (VH). After immunization, the transcriptional changes in VHH+ and VH+ B cells were also largely consistent. Our study not only elucidates the cellular context of HCAb production in camels, but also lays the foundation for the development of single B cell-based nanobody screening.
Project description:The domestic Bactrian camels were treated as one of the principal means of locomotion between the eastern and western cultures in history. However, whether they originated from East Asia or Central Asia remains elusive. To address this question, we perform whole-genome sequencing of 128 camels across Asia. The extant wild and domestic Bactrian camels show remarkable genetic divergence, as they were split from dromedaries. The wild Bactrian camels also contribute little to the ancestry of domestic ones, although they share close habitat in East Asia. Interestingly, among the domestic Bactrian camels, those from Iran exhibit the largest genetic distance and the earliest split from all others in the phylogeny, despite evident admixture between domestic Bactrian camels and dromedaries living in Central Asia. Taken together, our study support the Central Asian origin of domestic Bactrian camels, which were then immigrated eastward to Mongolia where native wild Bactrian camels inhabit.
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.
