Criscione Andrea, Tumino Serena, Avondo Marcella, Marletta Donata, Bordonaro Salvatore
Department of Agriculture, Food and Environment, University of Catania, Catania, 95123, Italy.
Arch Anim Breed. 2019 Jul 24;62(2):447-454. doi: 10.5194/aab-62-447-2019. eCollection 2019.
Selection, drift, gene flow and breeding have extensively shaped the genomic variability of domestic animals. In goat species, several mutations identified within the casein genes have been shown to affect the level of gene expression of milk production traits. The four casein genes - , , and - are organized in a cluster of 250 kb located in chromosome 6, and due to tight linkage, their genetic variability is well depicted by haplotypes which are transmitted to the progeny. Thirty single nucleotide polymorphisms (SNPs) located within the casein gene cluster were used to characterize the haplotype variability of six southern Italian goat breeds (Girgentana, Maltese, Rossa Mediterranea, Argentata dell'Etna, Messinese, Capra dell'Aspromonte). A representative sample of the Norwegian dairy goat breed (Norsk melkegeit) has been used as an out-group to obtain a weighted measure of genetic diversity in the metapopulation. A total of 54 haplotypes were detected among the seven breeds: 26, 9, 8 and 11 haplotypes were found at , , and respectively. The number of haplotypes per breed was 14 (Norwegian), 26 (Messinese), 27 (Rossa Mediterranea and Girgentana) and 31 (Maltese, Argentata dell'Etna and Capra dell'Aspromonte). The Maltese breed showed the highest number of private haplotypes, whereas the Norwegian goat recorded the highest number of shared haplotypes. The linkage disequilibrium analysis showed higher levels of association for the SNP pairs within casein loci than SNP pairs between casein loci, likely reflecting low levels of intra-genic recombination. The highest linkage disequilibrium values were found in and genes in all the breeds, except for Argentata dell'Etna and Rossa Mediterranea. The resolution of the haplotype diversity at the casein cluster can be exploited both for selective and conservative plans.
选择、漂变、基因流动和育种极大地塑造了家畜的基因组变异性。在山羊品种中，已证明在酪蛋白基因内鉴定出的几种突变会影响产奶性状的基因表达水平。四个酪蛋白基因——αs1-酪蛋白、αs2-酪蛋白、β-酪蛋白和κ-酪蛋白——位于6号染色体上一个250 kb的基因簇中，由于紧密连锁，它们的遗传变异性通过传递给后代的单倍型得到了很好的描述。位于酪蛋白基因簇内的30个单核苷酸多态性（SNP）被用于表征六个意大利南部山羊品种（吉尔根塔纳山羊、马耳他山羊、地中海红山羊、埃特纳银山羊、梅西纳山羊、阿斯普罗蒙特山羊）的单倍型变异性。挪威奶山羊品种（挪威奶山羊）的一个代表性样本被用作外群，以获得该集合种群中遗传多样性的加权度量。在这七个品种中共检测到54种单倍型：在αs1-酪蛋白、αs2-酪蛋白、β-酪蛋白和κ-酪蛋白中分别发现了26种、9种、8种和11种单倍型。每个品种的单倍型数量分别为14种（挪威奶山羊）、26种（梅西纳山羊）、27种（地中海红山羊和吉尔根塔纳山羊）以及31种（马耳他山羊、埃特纳银山羊和阿斯普罗蒙特山羊）。马耳他山羊品种显示出最高数量的私有单倍型，而挪威山羊记录的共享单倍型数量最多。连锁不平衡分析表明，酪蛋白基因座内的SNP对之间的关联水平高于酪蛋白基因座之间的SNP对，这可能反映了基因内重组水平较低。除了埃特纳银山羊和地中海红山羊外，在所有品种的αs1-酪蛋白和β-酪蛋白基因中发现了最高的连锁不平衡值。酪蛋白基因簇处单倍型多样性的解析可用于选择性和保护性计划。
