Differences Of Ob Gene Expression Between Lean And Obese Swine

Since the cloning of human and mouse ob gene, the structure, function, mutation, expression and affecting factors become the hot points of the researches for the molecular mechanism in obesity. Leptin is of vast biological functions, ob gene may be used in animal breeding for livestock selection, ob and OBR gene maybe used as quantitative trait locus for MAS (Marker Assisted Selection).The expression of ob gene is affected by many factors, including age, gender, food intake, fat content, hormone, immunological stress reaction, exercise, metals and transcription factors. The expressional differences of ob genes mainly are ob gene mRNA abundance in fat tissues and serum Leptin levels, and serum Leptin level is remarkably dependant with the body fat deposit. There are 3 methods to detect the ob gene expression: Radioactive Immunological Assay, Western blotting and Northern blotting.Researches have been conducted for the polymorphism of pig ob gene, serum Leptin level and their dependency with breeding values of weight, age and some lean rate traits, the immune stress reactions in pigs of some genotypes, the dependency of serum Leptin levels with carcass composition in cattle. More and more attentions are drawn to the research about the polymorphisms of ob gene and OBR gene, their dependency with growth performance, expecting to find some genetic markers for the dependency of the features of ob gene and OBR gene with the livestock performances, and a method to improve livestock performances.In this study, Nei Jiang Pig and Bamei Pig were employed to represent obese swine, Landrace and Duroc to represent lean swine, the ob gene mRNA relative abundances in subcutaneous fat tissues of the 4 swine breeds were detected using RT-PCR and Northern blotting method, and the serum Leptin levels of the 4 swine breeds were compared using Western blotting method. Then by the obgene coding region sequences of the 4 swine breeds, the homology of the reported ob gene coding region was analyzed, as well as that of reported Leptin sequences. For the first time, we discussed the ob gene expressional differences between Chinese obese swine breeds and imported lean swine breeds, compared the homology of reported ob gene coding region sequences and Leptin, and concluded as follows:1 There are far significant differences in ob gene mRNA abundances in subcutaneous fat tissues bwtween obese and lean swine (P<0. 01), and ob gene mRNA abundance in obese swine is 1. 21 times higher than in lean swine. The ob gene mRNA relative abundances of Nei Jiang pig, Bamei pig, Landrace and Duroc are 1.04, 0.985, 0.475 and 0.445; But difference between the ob gene mRNA abundances of the two obese swine breeds, Nei Jiang Pig and Bamei Pig, is insignificant, nor as the difference between the two lean swine breeds.2 The ob gene is not expressed in the porcine liver. By the results of RT-PCR and Northern blotting, we found that ob gene is expressed in porcine subcutaneous fat tissues, but not in porcine liver. This kind of expression style is the same as that in human and mouse, different to that in chicken.3 There are far significant differences in serum Leptin levels between obese and lean swine (P<0. 01), and serum Leptin level in obese swine is 3.23 times higher than in lean swine. This kind of increase is consistent with the ob gene mRNA abundance increase in obese swine than in lean swine. The serum Leptin relative levels of Nei Jiang pig, Bamei pig, Landrace and Duroc are 0. 943, 1.127, 0.278 and 0.211; compared to the standard Leptin sample, the serum Leptin level of the 4 swine breeds averaged 18. 86, 22. 54, 5. 56 and 4. 22ng/ml. But difference between the serum Leptin levels of the two obese swine breeds, Neijiang Pig and Bamei Pig, is insignificant, nor as the difference between the two lean swine breeds.4 Compared to lean swine, the regulation of ob gene expression is enlarged during translation after the ob gene transcription in obese swine, and there is special regulation mechanism during the translation procedure afte...