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 intensification of research projects on dromedary and the knowledge of the genetic diversity at the casein loci, the genetic structure of the Tunisian camel population still needs exploration. This study sought to determine the genetic diversity of 3 casein gene variants in 5 Tunisian camel ecotypes: c.150G>T at CSN1S1 (αS1-casein), g.2126A>G at CSN2 (β-casein), and g.1029T>C at CSN3 (κ-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 average CSN2 allele frequency of the total population. Allele 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 Tunisian, Sudanese, and Nigerian populations, although the global fixation index indicated that only 2.2% of the genetic 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.

[1]  G. Cosenza,et al.  A novel duplex ACRS-PCR for composite CSN1S1–CSN3 genotype discrimination in domestic buffalo , 2021, Italian Journal of Animal Science.

[2]  S. Ramadan,et al.  Association of β-casein gene polymorphism with milk composition traits of Egyptian Maghrebi camels (Camelus dromedarius) , 2020, Archives animal breeding.

[3]  M. Faghihi,et al.  Genomic prediction for growth using a low-density SNP panel in dromedary camels , 2020, Scientific Reports.

[4]  V. Landi,et al.  Bayesian Analysis of the Association between Casein Complex Haplotype Variants and Milk Yield, Composition, and Curve Shape Parameters in Murciano-Granadina Goats , 2020, Animals : an open access journal from MDPI.

[5]  J. Corander,et al.  Genomic signatures of domestication in Old World camels , 2020, Communications Biology.

[6]  F. Almathen,et al.  Genetic diversity and population structure of dromedary camel-types. , 2020, The Journal of heredity.

[7]  Cameron L. Aldridge,et al.  An empirical comparison of population genetic analyses using microsatellite and SNP data for a species of conservation concern , 2020, BMC Genomics.

[8]  Ahmed Hossam Mahmoud,et al.  Genetic diversity and population genetic structure of six dromedary camel (camelus dromedarius) populations in Saudi Arabia , 2019, Saudi journal of biological sciences.

[9]  E. Ciani,et al.  Old World camels in a modern world – a balancing act between conservation and genetic improvement , 2019, Animal genetics.

[10]  G. Erhardt,et al.  Casein Gene Cluster in Camelids: Comparative Genome Analysis and New Findings on Haplotype Variability and Physical Mapping , 2019, Front. Genet..

[11]  B. Faye,et al.  Genetic Improvement in Dromedary Camels: Challenges and Opportunities , 2019, Front. Genet..

[12]  G. Perry,et al.  Morphometric and genetic variation in 8 breeds of Ethiopian camels (Camelus dromedarius), , 2018, Journal of animal science.

[13]  B. Henry,et al.  Review: Adaptation of ruminant livestock production systems to climate changes. , 2018, Animal : an international journal of animal bioscience.

[14]  V. Uversky,et al.  Variability of Some Milk-Associated Genes and Proteins in Several Breeds of Saudi Arabian Camels , 2018, The Protein Journal.

[15]  Y. Ussenbekov,et al.  Results of Camelus dromedarius and Camelus bactrianus Genotyping by Alpha-S1-Casein, Kappa-Casein Loci, and DNA Fingerprinting , 2018, Cytology and Genetics.

[16]  A. Abushady,et al.  Weak Genetic Structure in Northern African Dromedary Camels Reflects Their Unique Evolutionary History , 2017, PloS one.

[17]  A. Noce,et al.  Variations at regulatory regions of the milk protein genes are associated with milk traits and coagulation properties in the Sarda sheep. , 2016, Animal genetics.

[18]  M. Hofreiter,et al.  Ancient and modern DNA reveal dynamics of domestication and cross-continental dispersal of the dromedary , 2016, Proceedings of the National Academy of Sciences.

[19]  A. Perna,et al.  The influence of casein haplotype on morphometric characteristics of fat globules and fatty acid composition of milk in Italian Holstein cows. , 2016, Journal of dairy science.

[20]  O. Othman,et al.  Genetic Variations in Two Casein Genes Among Maghrabi camels Reared in Egypt , 2016 .

[21]  P. Nagy,et al.  Review of present knowledge on machine milking and intensive milk production in dromedary camels and future challenges , 2016, Tropical Animal Health and Production.

[22]  G. Erhardt,et al.  Alpha S1-casein polymorphisms in camel (Camelus dromedarius) and descriptions of biological active peptides and allergenic epitopes , 2016, Tropical Animal Health and Production.

[23]  P. Burger,et al.  Validating local knowledge on camels: Colour phenotypes and genetic variation of dromedaries in the Nigeria-Niger corridor , 2015 .

[24]  Jukka Corander,et al.  The de novo genome assembly and annotation of a female domestic dromedary of North African origin , 2015, Molecular ecology resources.

[25]  Shishir K. Gupta,et al.  Comparative screening of single nucleotide polymorphisms in β-casein and κ-casein gene in different livestock breeds of India , 2015, Meta gene.

[26]  Huanming Yang,et al.  Camelid genomes reveal evolution and adaptation to desert environments , 2014, Nature Communications.

[27]  G. Erhardt,et al.  The β-casein in camels: molecular characterization of the CSN2 gene, promoter analysis and genetic variability. , 2014, Gene.

[28]  B. Faye,et al.  Lactation curves of dairy camels in an intensive system , 2013, Tropical Animal Health and Production.

[29]  G. Erhardt,et al.  Biochemical and molecular characterization of polymorphisms of αs1-casein in Sudanese camel (Camelus dromedarius) milk , 2013 .

[30]  G. Erhardt,et al.  Molecular characterization and genetic variability at κ-casein gene (CSN3) in camels. , 2013, Gene.

[31]  Surong Hasi,et al.  Genome sequences of wild and domestic bactrian camels , 2012, Nature Communications.

[32]  K. Kawasaki,et al.  The evolution of milk casein genes from tooth genes before the origin of mammals. , 2011, Molecular biology and evolution.

[33]  O. A. Haj,et al.  Compositional, technological and nutritional aspects of dromedary camel milk , 2010 .

[34]  B. Rekik,et al.  Genetic diversity in Tunisian dromedary (Camelus dromedarius) populations using microsatellite markers. , 2010 .

[35]  J. Delgado,et al.  The Canarian Camel: A Traditional Dromedary Population , 2010 .

[36]  A. Woolnough,et al.  Assessment and genetic characterisation of Australian camels using microsatellite polymorphisms , 2010 .

[37]  P. Ferranti,et al.  Short communication: molecular genetic characterization of ovine alpha(S1)-casein allele H caused by alternative splicing. , 2010, Journal of dairy science.

[38]  A. Caroli,et al.  Invited review: milk protein polymorphisms in cattle: effect on animal breeding and human nutrition. , 2009, Journal of dairy science.

[39]  B. Faye,et al.  The composition of camel milk: A meta-analysis of the literature data , 2009 .

[40]  B. Hayes,et al.  Casein haplotypes and their association with milk production traits in Norwegian Red cattle , 2009, Genetics Selection Evolution.

[41]  A. Kotzé,et al.  Microsatellite markers reveal low genetic differentiation among southern African Camelus dromedarius populations , 2007 .

[42]  A. Caroli,et al.  Focusing on the goat casein complex. , 2006, Journal of dairy science.

[43]  Mark Daly,et al.  Haploview: analysis and visualization of LD and haplotype maps , 2005, Bioinform..

[44]  Peter Donnelly,et al.  A comparison of bayesian methods for haplotype reconstruction from population genotype data. , 2003, American journal of human genetics.

[45]  O. Hanotte,et al.  Genetic diversity and relationships of indigenous Kenyan camel (Camelus dromedarius) populations: implications for their classification. , 2003, Animal genetics.

[46]  F. Balloux,et al.  The estimation of population differentiation with microsatellite markers , 2002, Molecular ecology.

[47]  S. Kappeler,et al.  Sequence analysis of Camelus dromedarius milk caseins , 1998, Journal of Dairy Research.

[48]  A. Rando,et al.  DNA polymorphisms of casein genes in Spanish dairy sheep , 1997 .

[49]  V. Sejian,et al.  Review paper: climate change and camel production: impact and contribution. , 2015 .

[50]  T. Khorchani,et al.  Classification of Maghrebi camels (Camelus dromedarius) according to their tribal affiliation and body traits in southern Tunisia , 2013 .

[51]  G. Cosenza,et al.  Genotyping at the CSN1S1 locus by PCR-RFLP and AS-PCR in a Neapolitan goat population , 2008 .

[52]  O Hammer-Muntz,et al.  PAST: paleontological statistics software package for education and data analysis version 2.09 , 2001 .