| Lipoproteins are lipids and protein complexes hold together by non-covalent bonds, where each type of lipoprotein has characteristic molecular weight, chemical composition, density and physiological role. In the first part of this study, the relationship among abdominal fat, total cholesterol, triglyceride and lipoprotein (HDL, LDL and VLDL) in fat (Anka) and lean (Rugao) chicken breeds was investigated. In the second part, LDL receptor mRNA in different tissues of lean and fat chickens was expressed. Thereafter, in the third part SNPs were screened in apoVLDL-II and lipoprotein lipase genes, their associations with abdominal fat and biochemical serum were evaluated. Similarly, their interactive effect on abdominal fat and biochemical serum concentrations was studied. Based on SNPs results, the genetic differentiation was assessed and phylogeny tree was constructed among Red jungle fowl, Wenchang, Silkies, Rugao and Anka chicken populations in the fourth part of our study.1. Body weight, abdominal fat weight and percentage of abdominal fat were significantly (P<0.01) different between fat and lean chicken, and similarly between males and females. Abdominal fat was positively correlated with body weight in both fat and lean chicken. Fat and lean chickens were significantly (P<0.01) differed in total cholesterol (TCH) and HDL levels. Males rather than females had significantly (P<0.01) higher levels of TCH and LDL. TCH was also positively correlated with HDL and LDL, whereas triglyceride was positively correlated with HDL and VLDL. In addition, abdominal fat was positively correlated with all biochemical serum in lean chickens, while in fat chickens was positively correlated with TCH and LDL.2. Total RNA from kidney, liver, intestine and abdominal fat tissues of fat and lean chickens were isolated by standard Trizol methods. Total RNA was reverse transcribed by reverse transcriptase of moloney murine leukemia virus, and the level of expression was determined by semi-quantitative RT-PCR. Results showed that the expression levels of low density lipoprotein receptor mRNA were significantly (P<0.05) different between abdominal fat and liver tissues. In addition, LDL receptor mRNA expression in liver tissue was significantly (P<0.05) different between fat and lean chickens. The expression of LDL receptor mRNA in liver of fat chickens was negatively correlated with abdominal fat weight. However, in lean chickens, was observed to be negatively correlated with total cholesterol, triglyceride, lipoprotein, abdominal fat weight and percentage of abdominal fat weight.3. Six SNPs in apoVLDL-II gene were identified among five chicken populations, at 1950(G/A), 2532(T/A), 2706(A/C), 2793(C/T), 4436 (T/C) and 4473 (T/G). Gene frequency between populations was differed significantly at VLDL9 and VLDL17 loci. SNP genotype in apoVLDL-II was found to be significantly (P<0.05) associated with abdominal fat weight at VLDL17 locus in Rugao breed. On the other hand, it was significantly (P<0.05) associated with abdominal fat weight at VLDL6, VLDL9 and VLDL10 in fat and lean chickens. SNP in apoVLDL-II gene was significantly P<0.05) associated with triglycerides and VLDL at VLDL9 locus in fat chicken and at VLDL10 locus in lean chicken. In addition, analysis of both breeds showed that SNPs genotype were significantly (P<0.05) associated with triglyceride and very low density lipoprotein at VLDL9 and VLDL17 loci, and with total cholesterol and high density lipoprotein at VLDL10 locus. Thus, we can conclude that individuals with homozygous AA genotype at VLDL9 locus have significantly (P<0.05) higher body weight, fat weight, triglyceride and VLDL levels. In contrast individuals with heterozygous genotype in VLDL10 locus exhibited significantly (P<0.05) lower body weight and fat weight, and significantly (P<0.05) higher total cholesterol and high density lipoprotein levels.4. Two SNPs were detected at 14538bp (C/A) and 14977bp (T/C) in lipoprotein lipase gene. Allele frequency was significantly (P<0.01) different in Rugao population at LPL10 locus. Abdominal fat was significantly (P<0.05) different between SNP genotypes at LPL10 locus in Anka breed. Genotype effect within both Anka and Rugao breeds showed that abdominal fat weight was significantly different (P<0.05) at LPL9 and LPL10 loci. In addition, SNPs at LPL 9 locus in Anka breed was significantly (P<0.05) associated with LDL level. Moreover, SNP genotype was significantly (P<0.05) associated with total cholesterol and high density lipoprotein at LPL10 locus in lean and fat chickens.5. The abdominal fat weight was significantly (P<0.05) higher in individuals with homozygous CC genotype of lipoprotein lipase compared to individuals with homozygous (TT) genotype. In apoVLDL-II gene homozygous (TT) genotype had significantly (P<0.05) higher body weight and fat weight than homozygous (CC) genotype. In addition, individuals with (TT) LPL and apoVLDL-II genotype had significantly (P<0.05) higher abdominal fat than those with (TT) LPL and (TC) apoVLDL-II. In addition, individuals with (TC) LPL and (TT) apoVLDL-II genotype was observed significantly (P<0.05) higher abdominal fat weight compared to individuals with (TT) LPL and (CC) apoVLDL-II genotype. On the other hand, individual with (CC) LPL and (TT) apoVLDL-II genotype showed significantly (P<0.05) higher abdominal fat compared to those with (CC) LPL and (TC) apoVLDL-II. In lipoprotein lipase (TT) genotype had significantly high total cholesterols and high density lipoprotein than (CC) genotype. In apoVLDL, heterozygous genotype observed to have significantly higher total cholesterol and high density lipoprotein levels than homozygous (TT) genotypes. The interaction of LPL and apoVLDL-II indicated that the homozygous (TT) LPL and apoVLDL genotypes had significantly (P<0.05) lower total cholesterol and high density lipoprotein levels compared to those have (TT) LPL and (TC) apoVLDL-II genotype. However, the individuals with (TC) LPL and (TT) apoVLDL were observed to have significantly (P<0.05) lower triglycerides and very low density lipoprotein than that with (TC) LPL and (TC) apoVLDL-II. In addition, individuals with (CC) LPL and (TT) apoVLDL-II showed lower high density lipoprotein levels than individuals with (CC) LPL and (TC) apoVLDL-II. Finally we can conclude that apoVLDL-II and lipoprotein lipase were candidate for abdominal fat and biochemical serum concentrations.6. SNPs detected in the functional genes among Red jungle fowl (Gallus gallus spadiceus) and domestic chickens were used to evaluate genetic diversity and construct phylogeny relationship. Anka showed the highest genetic diversity, effective number of allele and Shannon information index. In addition, Red jungle fowl showed the lowest genetic diversity and Shannon information index, whereas Rugao showed the lowest effective number of allele. All populations had medium polymorphism information content (PIC) except Wenchang had lower (PIC). The average genetic diversity, effective number of allele, Shannon information index and polymorphism information content across loci were 0.432±0.172, 1.898±0.568, 0.702±0.265 and 0.291±0.041, respectively. The average of total genetic diversity (HT), genetic diversity within population (HS), coefficient of genetic differentiation (GST) and gene flow across all loci were 0.420±0.029, 0.339±0.029, 0.197 and 2.077 respectively. The highest genetic distance was 0.288 between Anka and Silkies, and the lowest was 0.008 between Silkies and Wenchang. Red jungle fowl and Wenchang were more closely and genetically related than the other breeds, followed by Silkies and Rugao, and finally all were related with Anka.
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