Mastitis causes huge loss to the dairy sector and thus the selection of mastitis resistant animals will be a boost to this industry. So, the present investigation was undertaken to find out the association of leptin gene with mastitis by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genomic DNA was isolated from the blood of 40 Murrah buffaloes (including 20 mastitic animals), randomly selected, maintained at Govt. livestock farm, Hisar, Buffalo research centre, college of animal sciences and TVCC, LLRUVAS, Hisar, by phenol chloroform method. PCR amplification of the partial intron2 (213 bp) and exon3 (331 bp) of leptin gene was carried out using specific self designed primers and published primers, respectively. When 213 bp PCR products of intron2 and 331 bp PCR product of exon3 of leptin gene were digested with AluI and HphI; and HinfI and HaeIII restriction enzymes, respectively, it detected single genotype in both groups. So we conclude that the partial region of the leptin gene viz. intron2 and exon3 are monomorphic and could not be associated with the mastitis. At the same we would recommend that one should study the whole leptin gene with more restriction endonuclease enzymes to come at any final conclusion regarding the association of the leptin gene with the mastitis.
Key words: Leptin, PCR-RFLP, AluI, HphI, HinfI, HaeIII
Mastitis, inflammation of the one or more quarters of the mammary gland, is a major cause of economic losses to the dairy industry as it reduces milk yield, alters milk composition and increases treatment costs. An annual loss due to mastitis in cows and buffaloes, in India, has been calculated around Rs.7165.51 crores (Bansal and Gupta, 2009). Somatic cell count (SCC) of milk is mainly used for the diagnosis of the mastitis, as mastitis leads to increased SCC in milk and estimated genetic correlation between mastitis and SCC ranges between 0.53 and 0.77 (Koivula et al., 2005). Genetic variation in animal population is being used nowadays to select the mastitis resistant animals. Numerous functional candidate genes have been studied and many are found to be useful marker for the selection of mastitis resistance animals.
Leptin is a 16 kDa polypeptide hormone, made up of 167 amino acids with an amino-terminal secretory signal sequence of 21 amino acids (Glaum et al., 1996). It is a globular protein with a tertiary structure similar to a haemopoitic cytokine (Mantzoros and Moschos, 1998). It is produced primarily by fat cells but the presence of leptin was also demonstrated in the mammary gland tissue and in milk of different mammalian species (Zhang et al., 1994; McFadin et al., 2002). Leptin is mainly involved in maintaining the energy balance by controlling food intake and energy expenditure and it regulates the endocrine and immune functions (Houseknecht et al., 1998). It has been established that leptin plays a major role in both innate and adaptive immune responses....