Molecular phylogeny of the Bactrian camel based on mitochondrial Cytochrome b gene sequences

Genetic differentiation of Indian dromedary and Bactrian camel populations based on mitochondrial ATP8 and ATP6 genes

Camelids are acknowledged worldwide to endure hostile conditions prevalent in the hot as well cold deserts across the globe. Adaptations to climatic extremes have been associated with mitochondrial protein variants such as ATP8 and ATP6 in different species. The camel genetic resources of India are represented by 9 breeds of dromedary camels which inhabit hot arid and semi-arid zones of the country and a small population of Bactrian camels found in the cold desert of Ladakh. In this study, within and between breed genetic diversity in Indian dromedaries and their divergence from Bactrian camels was investigated based on ATP8/6 genes. Sequence analysis of a mitochondrial DNA fragment encompassing ATP8 and ATP6 genes identified 15 haplotypes in the dromedaries of India and 3 haplotypes in Bactrian camels. The values of haplotype diversity and nucleotide diversity were 0.647 and 0.00187 in the former and 0.679 and 0.00098, respectively in the latter. AMOVA analysis revealed 97.81% variance between the two species. Median-Joining network delineated three distinct mitochondrial haplogroups for Camelus dromedarius, Camelus ferus and Camelus bactrianus. Clear demarcation of the old world (Dromedary and Bactrian camels) and new world camelids (Alpaca, llama, guanaco and vicugna) was evident through the phylogenetic analysis.

Coxiella burnetii in Dromedary Camels (Camelus dromedarius): A Possible Threat for Humans and Livestock in North Africa and the Near and Middle East?

The "One Health" concept recognizes that human health is connected to animal health and to the ecosystems. Coxiella burnetii-induced human Q fever is one of the most widespread neglected zoonosis. The main animal reservoirs responsible for C. burnetii transmission to humans are domesticated ruminants, primarily goats, sheep, and cattle. Although studies are still too sparse to draw definitive conclusions, the most recent C. burnetii serosurvey studies conducted in herds and farms in Africa, North Africa, Arabian Peninsula, and Asia highlighted that seroprevalence was strikingly higher in dromedary camels (Camelus dromedarius) than in other ruminants. The C. burnetii seroprevalence in camel herds can reach more than 60% in Egypt, Saudi Arabia, and Sudan, and 70 to 80% in Algeria and Chad, respectively. The highest seroprevalence was in female camels with a previous history of abortion. Moreover, C. burnetii infection was reported in ticks of the Hyalomma dromedarii and Hyalomma impeltatum species collected on camels. Even if dromedary camels represent <3% of the domesticated ruminants in the countries of the Mediterranean basin Southern coast, these animals play a major socioeconomic role for millions of people who live in the arid zones of Africa, Middle East, and Asia. In Chad and Somalia, camels account for about 7 and 21% of domesticated ruminants, respectively. To meet the growing consumers demand of camel meat and milk (>5 million tons/year of both raw and pasteurized milk according to the Food and Agriculture Organization) sustained by a rapid increase of population (growth rate: 2.26-3.76 per year in North Africa), dromedary camel breeding tends to increase from the Maghreb to the Arabic countries. Because of possible long-term persistence of C. burnetii in camel hump adipocytes, this pathogen could represent a threat for herds and breeding farms and ultimately for public health. Because this review highlights a hyperendemia of C. burnetii in dromedary camels, a proper screening of herds and breeding farms for C. burnetii is urgently needed in countries where camel breeding is on the rise. Moreover, the risk of C. burnetii transmission from camel to human should be further evaluated.

Mitochondrial DNA variation and phylogeography of Old World camels

Objective

Old World camels are a valuable genetic resource for many countries around the world due to their adaptation to the desert environment. At present, Old World camels have encountered the challenge of unprecedented loss of genetic resources. Through our research, we would reveal the population structure and genetic variation in Old World camel populations, which provides a theoretical basis for understanding the germplasm resources and origin and evolution of different Old World camel populations.

Methods

In the present study, we assessed mtDNA control region sequences of 182 individuals from Old World camels to unravel genetic diversity, phylogeography, and demographic dynamics.

Results

Thirty-two haplotypes confirmed by 54 polymorphic sites were identified in the 156 sequences, which included 129 domestic and 27 wild Bactrian camels. Meanwhile, 14 haplotypes were defined by 47 polymorphic sites from 26 sequences in the dromedaries. The wild Bactrian camel population showed the lowest haplotype and nucleotide diversity, while the dromedaries investigated had the highest. The phylogenetic analysis suggests that there are several shared haplotypes in different Bactrian camel populations, and that there has been genetic introgression between domestic Bactrian camels and dromedaries. In addition, positive values of Tajima’s D and Fu’s Fs test demonstrated a decrease in population size and/or balancing selection in the wild Bactrian camel population. In contrast, the negative values of Tajima’s D and Fu’s Fs test in East Asian Bactrian camel populations explained the demographic expansion and/or positive selection.

Conclusion

In summary, we report novel information regarding the genetic diversity, population structure and demographic dynamics of Old World camels. The findings obtained from the present study reveal that abundant genetic diversity occurs in domestic Bactrian camel populations and dromedaries, while there are low levels of haplotype and nucleotide diversity in the wild Bactrian camel population.

Cytochrome b conservation between six camel breeds reared in Egypt

This study was aimed to assess cytochrome b conservation in six breeds of camels reared in Egypt and to compare its sequence with those of other livestock species. The 208-bp fragments from camel mtDNA cyto b were amplified using PCR for 54 camels belonging to 6 camel breeds reared in Egypt. The alignment of camel cyto b sequences showed the presence of two polymorphic sites resulting in four haplotypes and their nucleotide sequences were submitted to GenBank under the accession numbers: KX909894-KX909897. The genetic distances between tested camel breeds were zero between Baladi, Fallahi and Maghrabi breeds whereas they were at low value between the other three breeds: Mowaled, Sodany and Somali. Neighbor-joining showed 4 branches; one of them include most of the tested animals and another one contains 2 Somali animals which is considered a specific haplotype for this breed. The other two branches are mixed between Sodani and Mowaled breeds. Neighbor-joining tree was constructed between cyto b sequences of our tested camels and their sequences from livestock species include Camelus dromedaries, Camelus bactrianus, Ovis aries, Capra hircus, Bubalus bubalis, Bos Taurus and Sus scrofa. The result confirmed that our camel breeds belong to Camelus dromedaries and are clearly separated from other species. It is concluded that cyto b sequence is highly conserved among all camel breeds reared in Egypt which belong to Camelus dromedaries in addition to the advantage of cyto b in differentiation between different livestock sources which enables it to widely use for the adulteration detection in mixed meat.