Tunisian camel casein gene characterization reveals similarities and differences with Sudanese and Nigerian populations

Milk is a primary protein source that has always played a role in mammalian health. Despite the inten-sification of research projects on dromedary and the knowledge of the genetic diversity at the casein loci, the genetic structure of the Tunisian camel popula-tion still needs exploration. This study sought to de-termine the genetic diversity of 3 casein gene variants in 5 Tunisian camel ecotypes: c.150G > T at CSN1S1 (alpha S1-casein), g.2126A > G at CSN2 (beta-casein), and g.1029T > C at CSN3 (& UKappa;-casein). The obtained results were compared with data published on Sudanese and Nigerian camels to establish the level of differentiation within and between populations. A total of 159 blood samples were collected from 5 Tunisian camel ecotypes and the extracted DNA was genotyped by PCR-RFLP. A streamlined genotyping protocol was also developed for CSN3. Results indicated that allele T was quite rare (0.06) at CSN1S1 for all ecotypes. Minor allele frequency was found for G (0.462) in CSN2 except for Ardhaoui Medenine ecotype who deviated from the av-erage CSN2 allele frequency of the total population. Al-lele C showed minor allele frequency of 0.384 in CSN3. Among the Tunisian population, GAT (0.343) was the most represented haplotype in all ecotypes except for Ardhaoui Medenine, where GGC (0.322) was the most frequent one. Significant differences in heterozygosity and local inbreeding were observed across the Tuni-sian, Sudanese, and Nigerian populations, although the global fixation index indicated that only 2.2% of the ge-netic variance is related to ecotype differences. Instead, phylogenetic analysis revealed a closer link between the Tunisian and Sudanese populations through a clade subdivision with 3 main branches among the ecotypes. This study represents the first attempt to understand casein gene variability in Tunisian camels; with further study, milk traits and genetic differentiation among populations can be associated with the history of camel domestication.

Automated summary

This study explores the genetic structure and variability of casein genes in Tunisian camel populations. The results show that Tunisian camels exhibit genetic diversity in casein genes, with significant differences between different ecotypes. There is a close relationship between Tunisian and Sudanese camel populations, and genetic differentiation among populations is associated with the history of camel domestication. This study is of great importance for understanding the biological characteristics of camels and the history of camel domestication.