RESUMO
Estimation of genetic parameters is the most important component of an organized selection program. With respect to economic traits, such as wool and mutton traits, production costs can be reduced through a suitable selection program focused on genetic improvement. This study aimed to evaluate genetic parameters of fleece and post-weaning growth traits in sheep. Greasy fleece weight at 6, 16, 28, 40, and 52 months of age (GFW1, GFW2, GFW3, GFW4, and GFW5) represented characteristics of wool quantity. Staple length at shoulder, side, and rump (SL1, SL2, and SL3), fiber diameter, and percentage of true wool (TW%) were used as characteristics of wool quality. Live body weight at 6, 9, and 12 months of age (BW6, BW9, and BW12) reflected post-weaning growth characteristics. These data were collected over 23 years, from 1989 to 2012, at the Makuie Sheep Breeding and Raising Station (MSBS). Estimations were calculated using the derivative-free restricted maximum likelihood (DFREML) model. Direct heritability estimates, based on single-trait analyses, ranged from 0.10 (GFW1) to 0.80 (TW%). Additive genetic correlations among the traits ranged from highly negative (-0.46) to highly positive (0.99). The log likelihood ratio test (LRT) was used for selection of the most appropriate model. Based on the LRT, direct additive genetic and maternal permanent environmental effects were considered as the main sources of variation in the studied traits.
Assuntos
Peso Corporal/genética , Ovinos/genética , Lã , Análise de Variância , Animais , Cruzamento , Modelos Animais , Modelos Genéticos , Característica Quantitativa Herdável , Seleção Genética , Ovinos/classificação , DesmameRESUMO
Myostatin, a transforming growth factor-beta superfamily member, has been well documented as a negative regulator of muscle growth and development. Myostatin, which has 376 amino acids, is synthesized as a precursor protein. Polymorphism of the myostatin gene in Makoei sheep was investigated by PCR and single-strand conformation polymorphism technique (SSCP). Genomic DNA of 92 sheep was isolated from whole blood. A 417-bp myostatin intron I segment was amplified by standard PCR, using locus-specific primers. Four SSCP patterns, representing four different genotypes, were identified. The frequencies of the genotypes were 0.413, 0.293, 0.130, and 0.163 for AD, AC, AE, and BC, respectively. Allele frequencies were 0.4185, 0.0815, 0.2283, 0.2065, and 0.0652 for A, B, C, D, and E, respectively. Observed heterozygosity was 0.7192. There was significant deviation from Hardy-Weinberg equilibrium for this locus. Analysis of myostatin gene sequences revealed heterozygous SNPs, which were in agreement with results obtained in the SSCP analysis. We concluded that SSCP analysis is a quick, sensitive and reliable technique for determination of DNA polymorphisms. The effect of these genotypes on some traits was investigated, and the AD genotype was found to be associated with birth weight. No phenotypic associations were detected with the other genotypes. No associations of myostatin variants with weight gain were detected. We conclude that polymorphism in the ovine myostatin gene is associated with birth weight, but not with weight gain in Iranian Makoei sheep.
Assuntos
Peso ao Nascer/genética , Estudos de Associação Genética , Miostatina/genética , Polimorfismo de Nucleotídeo Único/genética , Carneiro Doméstico/genética , Aumento de Peso/genética , Animais , Cruzamento , Loci Gênicos/genética , Genótipo , Irã (Geográfico) , Polimorfismo Conformacional de Fita Simples/genéticaRESUMO
[reaction: see text] This study is a multinational, multidisciplinary contribution to the thermochemistry of dimethyl1,4-cubanedicarboxylate and the corresponding isomeric, cuneane derivative and provides both structural and thermochemical information regarding the rearrangement of dimethyl 1,4-cubanedicarboxylate to dimethyl 2,6-cuneanedicarboxylate. The enthalpies of formation in the condensed phase at T = 298.15 K of dimethyl 1,4-cubanedicarboxylate (dimethyl pentacyclo[4.2.0.0.(2,5)0.(3,8)0(4,7)]octane-1,4-dicarboxylate) and dimethyl 2,6-cuneanedicarboxylate (dimethyl pentacyclo[3.3.0.0.(2,4)0.(3,7)0(6,8)]octane-2,6-dicarboxylate) have been determined by combustion calorimetry, delta(f) H(o)m (cr)/kJ x mol(-1) = -232.62 +/- 5.84 and -413.02 +/- 5.16, respectively. The enthalpies of sublimation have been evaluated by combining vaporization enthalpies evaluated by correlation-gas chromatography and fusion enthalpies measured by differential scanning calorimetry and adjusted to T = 298.15 K, delta(cr) (g)Hm (298.15 K)/kJ x mol(-1) = 117.2 +/- 3.9 and 106.8 +/- 3.0, respectively. Combination of these two enthalpies resulted in delta(f) H(o)m (g., 298.15 K)/kJ x mol(-1) of -115.4 +/- 7.0 for dimethyl 1,4-cubanedicarboxylate and -306.2 +/- 6.0 for dimethyl 2,6-cuneanedicarboxylate. These measurements, accompanied by quantum chemical calculations, resulted in values of delta(f) Hm (g, 298.15 K) = 613.0 +/- 9.5 kJ x mol(-1) for cubane and 436.4 +/- 8.8 kJ x mol(-1) for cuneane. From these enthalpies of formation, strain enthalpies of 681.0 +/- 9.8 and 504.4 +/- 9.1 kJ x mol(-1) were calculated for cubane and cuneane by means of isodesmic reactions, respectively. Crystals of dimethyl 2,6-cuneanedicarboxylate are disordered; the substitution pattern and structure have been confirmed by determination of the X-ray crystal structure of the corresponding diacid.