Homogeneity of Arabian Peninsula dromedary camel populations with signals of geographic distinction based on whole genome sequence data

Dromedary camels in the Arabian Peninsula distribute along different geographical and ecological locations, e.g. desert, mountains and coasts. Here, we are aiming to explore the whole genome sequence data of ten dromedary populations from the Arabian Peninsula to assess their genetic structure, admixture levels, diversity and similarity indices. Upon including reference dromedary and Bactrian camel populations from Iran and Kazakhstan, we characterise inter-species and geographic genetic distinction between the dromedary and the Bactrian camels. Individual-based alpha genetic diversity profiles are found to be generally higher in Bactrian camels than dromedary populations, with the exception of five autosomes (NC_044525.1, NC_044534.1, NC_044540.1, NC_044542.1, NC_044544.1) at diversity orders (q ≥ 2). The Arabian Peninsula camels are generally homogenous, with a small degree of genetic distinction correlating with three geographic groups: North, Central and West; Southwest; and Southeast of the Arabian Peninsula. No significant variation in diversity or similarity indices are observed among the different Arabian Peninsula dromedary populations. This study contributes to our understanding of the genetic diversity of Arabian Peninsula dromedary camels. It will help conserve the genetic stock of this species and support the design of breeding programmes for genetic improvement of favorable traits.

Screening and Identification of Differential Ovarian Proteins before and after Induced Ovulation via Seminal Plasma in Bactrian Camels

Camelidae are induced ovulators whose ovulation is tightly regulated by multiple factors. Understanding the biological mechanisms underlying follicular development, hormone secretion, and ovulation requires investigating the potential molecular pathways involved. However, little is known about these pathways in Bactrian camels. To screen and identify candidate biomarkers after inducing ovulation, this study performed comprehensive proteomic and molecular biological analyses of the ovaries from two camel groups (n = 6). We identified 5075 expressed ovarian proteins, of which 404 were differentially expressed (264 upregulated, 140 downregulated) (p < 0.05 or p < 0.01), in samples from plasma-induced versus control camels. Gene ontology annotation identified the potential functions of the differentially expressed proteins (DEPs). These results validated the differential expression for a subset of these proteins using Western blot (p < 0.05) and immunofluorescence staining. Three DEPs (FST, NR5A1, and PRL) were involved in neurochemical signal transduction, as well as endocrine and reproductive hormone regulatory processes. The Kyoto Encyclopedia of Genes and Genomes analysis indicated the involvement of several pathways, including the calcium, cAMP, gonadotropin-releasing hormone, MAPK, and neuroactive ligand–receptor signaling pathways, suggesting that induced ovulation depends on the hypothalamic–pituitary–ovarian axis. Identifying these candidate biomarkers enables a better understanding of Bactrian camel reproduction. Ovarian proteomic profiling and the measurement of selected proteins using more targeted methods is a promising approach for studying induced-ovulation mechanisms.

A Cross-Species Transmission of a Camel-Derived Genotype 8 Hepatitis E Virus to Rabbits

Novel genotypes of hepatitis E virus (HEV), i.e., HEV-5, HEV-7, and HEV-8, have been identified in wild boar, dromedary camels, and Bactrian camels, respectively, and they transmit to cynomolgus monkeys in a trans-species manner, raising the potential for zoonotic infection. Rabbits are the natural reservoir for rabbit HEV, but they are also susceptible to HEV-3 and HEV-4. It has been unknown whether rabbits are susceptible to HEV-5, HEV-7, and HEV-8. To investigate the infectivity of novel HEVs in rabbits and to assess whether rabbits are appropriate animal models for these HEVs, we inoculated Japanese white rabbits with HEV-5, HEV-7, and HEV-8, respectively. We observed that viral RNA was present in the fecal specimens of the HEV-8-inoculated rabbits and anti-HEV IgG antibodies were present in its sera, although anti-HEV IgM was undetectable and no significant elevation of ALT was observed. These results indicated that HEV-8 crossed species and infected the rabbits. No evidence for replication was observed in HEV-5 and HEV-7, suggesting that rabbits are not susceptible to these genotypes. The antibodies elicited in the HEV-8-infected rabbits did not protect them from the rabbit HEV challenge, suggesting that the antigenicity differs between HEV-8 and rabbit HEV. Antigenic analyses demonstrated that anti-HEV-8 antibodies reacted more strongly with homologous HEV-8 virus-like particles (VLPs) compared to heterologous rabbit HEV VLPs, but anti-rabbit HEV antibody had similar reactivity to the VLPs of rabbit HEV and HEV-8, suggesting that HEV-8 lacks some epitope(s) that exist in rabbit HEV and induced the neutralizing antibodies against rabbit HEV.

Palaeogenomics reveal a hybrid origin of the world's largest Camelus species

The extinct Camelus knoblochi is known as the largest camel in genus Camelus, but its relationship to modern Camelus species remains unclear. In this study, we reported the first mitochondrial and nuclear analyses of seven Late Pleistocene C. knoblochi samples from Northeastern China. We found that they are inseparable to wild Bactrian camel on the matrilineal side, but belong to a distinct cluster on the biparental nuclear side. Further admixture proportion analyses suggested hybrid ancestry between both the ancestors of the modern wild and domesticated Bactrian camels, with ~65% contribution from the former and ~35% from the later. By calculating the coalescence time for three Camelus species above, we estimated the hybridization event occurred between approximately 0.8 and 0.33 Ma. We also used Bayesian skyline to reconstruct the maternal demographic trajectories for different Camelus to better compare their evolutionary histories. Our results provide molecular insights into C. knoblochi and fill in a vital piece in understanding the genus Camelus.

Reversible insulin resistance helps Bactrian camels survive fasting

Camels have hunger tolerance and can adapt to the severe environment of the desert. Through the comparison of insulin signalling pathway genes in different tissues in different eating periods (feeding, fasting and recovery feeding), it was found that IRS1, PIK3CB, PIK3R1 and SLC2A4 expression was significantly downregulated in the fore hump and hind hump during the fasting period. In addition, there was no difference in serum insulin levels among the three stages. However, the serum leptin and adiponectin levels decreased significantly during fasting. Additionally, insulin tolerance tests during the three stages showed that camels were insensitive to insulin during fasting. Further study of the serum metabolites showed that serum branched-chain and aromatic amino acid levels increased during the fasting period. Finally, analysis of microbial diversity in camel faeces at different stages showed that during the fasting period, the proportion of Firmicutes and Actinobacteria increased, while that of Bacteroides and the butyrate-producing bacterium Roseburia decreased. The results of this study show that fasting is accompanied by changes in the activation of insulin pathways in various camel tissues, normal insulin levels, and increased lipolysis and insulin resistance, which return to normal after eating.

Historical traces and perspectival possibilities of traditional camel keeping in Carpathian Basin

In this paper we have gathered and put into context all accessible sources regarding one-hump (dromedary—Camelus dromedarius) or two-hump Bactrian camels (Camelus bactrianus) in the Carpathian Basin. Reviewed sources and empirical statements have pointed out the growing European demand for camel meat and milk. These species are capable of grazing overexploited and bush-encroached pastures, besides producing valuable fibre in the form of camel hair, and be used in the tourism business as well. Because of anatomical and physiological adaptations, both species are capable of digesting rough fibre and vegetation unused by other livestock species. Therefore, camels are the ideal choice for pasture rehabilitation, especially in shrublands and overgrown areas. Both species are flexible browsers in extensive grazing systems due to their adaptation to steppe regions. Dromedaries are more suited to dry hot ecosystems while Bactrian camels are more adapted to a cold and wetter environment. Dromedary and Bactrian camel cross-breeding practices present modern solutions for introducing these species into pasture-based livestock farming. Dromedary genetic dominance increases milk production with lower milk fat. Bactrian genes deliver higher wool production and more resilient calves. Beyond the agricultural and conservation functions, the ethnographical and cultural roles are also important in Hungarian folklore.

Expression of the NSE, SP, NFH and DβH in Normal and Cryptorchid Testes of Bactrian Camel

Background: Neuroendocrine substances play important roles in regulating the normal physiological functions of testicles.The purpose of this study is to explore the localization and effects of four neuroendocrine markers(NSE, SP, NFH and DβH) in normal and cryptorchid testes of Bactrian camels.Methods: The cryptorchid testes were located in the abdominal cavity and were collected by orchiectomy. Fresh testes tissues were processed into small pieces and then divided into three samples. One sample was frozen in liquid nitrogen for western blotting hybridization reaction, while the other sample was fixed with 4% paraformaldehyde solution for histochemical analysis, and the third fixed in glutaraldehyde for transmission electron microscopy observation.Results: The results showed that cryptorchidism caused a reduction in layers of spermatogenic epithelium and decreased glycogen positivity in the basement membrane.The ultrastructure revealed that macrophages were always found around the Leydig cells, which were crowded with swelling mitochondria in cryptorchidism. Expression of NSE in the Leydig cells of cryptorchidism was significantly weakened compared to that in the normal group(p<0.01). We found that SP was always distributed along the nerve fibers in normal testes and was expressed in the Leydig cells of cryptorchidism. However, expression of NFH in the cryptorchidic tissue was strongly positive in spermatogenic epithelium, with limited expression in Leydig cells and no expression in peritubular myoid cells. Therefore, expression of DβH in the Sertoli cells was comparatively strong in both the normal and cryptorchidism groups.NFH and DβH expression was significantly increased in the cryptorchidism group compared with the nomal group(p<0.01).Conclusions: These findings indicated that the underdeveloped seminiferous epithelium and pathological changes in cryptorchid tissue in Bactrian camels were potentially related to a disorder in glycoprotein metabolism.Our results suggest that NSE and SP could helpful to judge the pathological changes of cryptorchidism. The present study provides the first evidence at the protein level for the existence of NFH and DβH in Sertoli and Leydig cells in Bactrian camel cryptorchidism and provides a more in-depth understanding of neuroendocrine regulation is crucial for animal cryptorchidism.

Molecular identification and biological characterization of Cryptosporidium muris from camels (Camelus bactrianus) in China

Background Cryptosporidium is an opportunistic pathogen that infects a wide variety of vertebrates. The aim of the present study was to characterize Cryptosporidium spp. isolates from Bactrian camels and to foster further understanding of the biological characteristics of the pathogen. Methods Fecal specimens were collected from two 4-year-old Bactrian camels resident at the Kaifeng City Zoo in China and examined for Cryptosporidium. Fecal specimens were screened using the floatation method, and then genomic DNA was extracted from the oocysts and identified by nested-PCR amplification of the small subunit ribosomal RNA (SSU rRNA) gene, the actin gene and the Cryptosporidium oocyst wall-protein (COWP) gene. Subtype analysis was performed based on four minisatellite (MS) loci (MS1, MS2, MS3 and MS16) that were aligned and phylogenetically analyzed to determine the species and subtype of Cryptosporidium. We then established a BALB/c mice infection model and further verified the results through clinical status, pattern of oocyst excretion and histological examination. Results Cryptosporidium oocyst isolates from the two Bactrian camels had an average (± standard deviation) size of 7.49 ± 0.13 × 5.70 ± 0.10 μm (n = 50). The sequencing and phylogenetic analysis confirmed the species as C. muris. Multilocus sequence typing analysis indicated that the subtypes were M13, M4, M1 and M5. Following the inoculation of BALB/c mice, we found that the prepatent period and number of oocysts per gram increased with increasing infective dose. Oocysts were first detected in the feces of BALB/c mice at 7–8 days post-infection (dpi), with levels peaking twice thereafter, at 15–16 dpi and 19–20 dpi. Histology and scanning electron microscopy studies showed that the stomach contained gastric pits filled with Cryptosporidium that adhered to the surface of gastric mucosa gland epithelial cells, causing the latter to deform, swell and become disordered. Conclusions The findings of this study indicated that oocysts isolated from Bactrian camels were from C. muris. This is the first report of C. muris isolated from camels in China. More epidemiological data are needed to understand the prevalence and transmission of C. muris in camels in different geographic areas. Graphical abstract