Genetic polymorphism of exon 9-11 of the leptin gene receptor in breeder hens of Mazandaran native fowls

Leptin is a 16 kDa protein synthesized by white adipose tissue and involved in regulation of feed intake, energy balance, fertility and immune function. In order to evaluate the leptin gene receptor polymorphism, we used a restriction fragment length polymorphism (RFLP) method. Blood samples were collected from 100 randomly chosen Mazandaran native fowls. Genomic DNA was extracted using modified salting-out method and amplified polymerase chain reaction technique. Exon and intron 9-11 of the fowl leptin gene receptor was amplified to produce a 382 bp fragment. The PCR products were electrophoresed on 1% agarose gel and stained by etidium bromide. Then, amplicons with Tsp509I were digested and revealed two alleles, A and B. Data were analysed using PopGene 32 package. In this population, AA, AB, BB genotype have been identified with the 69.14, 30.16 and 0.7% frequencies. A and B alleles frequencies were 0.84 and 0.16, respectively. χ2 test did not show Hardy–Weinberg equilibrium in this population (p<0.05). Further association analysis is required to clarify the effects of these marker genotypes on production traits in this breeder flock.Key words: Leptin gene receptor, polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP),polymorphism, breeder hen

Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models

Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05–0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954)

Study of polymorphism of leptin gene receptor in Mazandaran fowls

In chickens, leptin is expressed mainly in the liver and adipose tissue. In Iran, Mazandaran native fowls are under recording and breeding programs, but according to the action modes and importance of the leptin receptor, its polymorphisms can be related to economical traits such as body weight. In this study, in order to identify allelic polymorphism in leptin gene receptor, a restriction fragment length polymorphism (RFLP) method was used. Blood samples were collected randomly from 100 individuals. The DNA extraction was based on a salting-out method, while an amplified polymerase chain reaction technique was used. The quantity and quality of extracted DNA were examined using spectrophotometric and agarose gel electrophoresis. A strategy, employing polymerase chain reaction, was used to amplify a 374 bp fragment of 9 to 11 exon leptin gene receptor. Digestion of amplicons with HaeIII revealed leptin gene receptor. The obtained results from restriction digestion showed none of the polymorphism in leptin receptor gene, so all samples were monomorph due to the fact that there was no mutation that was related to polymorphism.Key words: Leptin gene receptor, PCR- RFLP, polymorphism, fowl, HaeIII