Productivity in dairy cattle and buffaloes depends on the genetic factors governing the production of milk and milk constituents as well as genetic factors controlling disease resistance or susceptibility. The immune system is the adaptive defense system that has evolved in vertebrates to protect them from invading pathogens and also carcinomas. It is remarkable in the sense that it is able to generate an enormous variety of cells and biomolecules which interact with each other in numerous ways to form a complex network that helps to recognize, counteract, and eliminate the apparently limitless number of foreign invading pathogens/molecules. The major histocompatibility complex which is found to occur in all mammalian species plays a central role in the development of the immune system. It is an important candidate gene involved in susceptibility/resistance to various diseases. It is associated with intercellular recognition and with self/nonself discrimination. It plays major role in determining whether transplanted tissue will be accepted as self or rejected as foreign.

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The genetic relationships of five Indian horse breeds, namely Marwari, Spiti, Bhutia, Manipuri and Zanskari were studied using microsatellite markers. The DNA samples of 189 horses of these breeds were amplified by polymerase chain reaction using 25 microsatellite loci. The total number of alleles varied from five to 10 with a mean heterozygosity of 0.58^0.05. Spiti and Zansakari were the most closely related breeds, whereas, Marwari and Manipuri were most distant apart with Nei's D A genetic distance of 0.071 and 0.186, respectively. In a Nei's D A genetic distances based neighbour joining dendrogram of these breeds and a Thoroughbred horse outgroup, the four pony breeds of Spiti, Bhutia, Manipuri and Zanskari clustered together and then with the Marwari breed. All the Indian breeds clustered independently from Thoroughbreds. The genetic relationships of Indian horse breeds to each other correspond to their geographical/environmental distribution.Keywords: genetic diversity, horse breeds, India, microsatellite markers IntroductionThe Indian horse breeds are distinct not only because of their adaptation to different agro-climatic conditions prevailing in the country, but also because they have unique traits such as sturdiness, stiffness, endurance potential, relative disease resistance etc. However, the changed scenario after development of the road network and mechanisation combined with indiscriminate breeding with exotic or nondescript animals has led to drastic decline in the populations of these breeds. Since, presently only a few thousand true breeding horses of each of these breeds are available (Singhvi, 2001;Yadav et al., 2001), it is necessary to evolve strategies for their conservation. The evaluation of genetic diversity/relationships among livestock breeds is an important prerequisite for developing cost-effective and meaningful breed conservation/improvement programmes. The microsatellite DNA markers, due to their highly polymorphic nature, have been extensively employed in the analysis of genetic diversity amongst breeds of various livestock species including horses (Bjornstad et al., 2000;Cañ ó n et al., 2000;Kelly et al., 2002;Tozaki et al., 2003;Achmann et al., 2004;Aberle et al., 2004;Solis et al., 2005;Glowatzki-Mullis et al., 2006). The present study was undertaken to characterise five Indian horse breeds for genetic variation and to establish relationships amongst them using a set of 25 microsatellite markers. The Thoroughbred horses, which are most common exotic horses in India, were also included in our study as an outgroup. Material and methods SamplesThe blood samples were collected from 189 horses of five Indian horse breeds from their respective areas of distribution (Figure 1). The breeds involved and their sample sizes were: Marwari (42), Spiti (32), Bhutia (26), Manipuri (47) and Zanskari (42). The blood samples were also collected from Thoroughbred (24) horses from Haryana state. The Marwari horses are native to Marwar region of Rajsthan province and are supposed to have been evol...

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Bovine lymphocyte antigen DRB 3.2 (BoLA-DRB3.2) gene encodes for the beta chain of the major histocompatibility complex (MHC) class II molecule in cattle, which is a glycoprotein present on the surface of antigen-presenting cells. This locus shows extensive polymorphism in it. The objective of the present study was to genotype the BoLA-DRB3.2 locus in Kankrej cattle (n = 50) by PCR-RFLP. Bovine DNA was isolated from aliquots of whole blood. Primers specific for exon 2 of the bovine lymphocyte antigen (BoLA)-DRB3 gene were used to amplify the region. The 304-bp amplified product of the DRB3 gene was separately digested with restriction endonucleases RsaI, BstYI, and Hae III. Twenty-four BoLA-DRB 3.2 alleles were identified with frequencies ranging from 1 to 22.0%. Twenty-one alleles of the total 24 alleles were similar to those reported earlier; 3 alleles were new and had not been reported previously. The allele BoLA-DRB3.2*34 occurred at the highest frequency of 22% (approx.) in the Kankrej animals studied. Six alleles (BoLA-DRB3.2 *34, *15, *06, *20, *37, and *20) accounted for almost 71% of the total alleles observed to be present in the Kankrej animals. All the new alleles observed were present at frequencies of 1%. The results obtained in the present study demonstrated that the BoLA DRB3.2 locus is highly polymorphic in the Kankrej cattle.