Mapping of Quantitative Trait Loci for Growth and Carcass-Related Traits in Chickens Using a Restriction-Site Associated DNA Sequencing Method.

In the present study, quantitative trait loci (QTLs) analysis was performed to identify the chromosomal positions of growth and carcass-related trait QTLs using 319 F2 chickens obtained from intercrosses of an Oh-Shamo male and four White Plymouth Rock females. Body weight was measured weekly until the birds were 7 weeks old. Carcass-related traits were also measured at this timepoint. A genetic linkage map was constructed using 545 single nucleotide polymorphism (SNP) markers that were developed using a restriction-site associated DNA sequencing method. The linkage map included the 23 autosomes and the Z chromosome. Using simple interval QTL mapping, we were able to identify 10 significant and suggestive main-effect QTLs for growth and carcass-related traits present on chromosomes 1, 2, 3, 5, 8, 19, 24, and Z. These loci explained 5.60-16.52% of the phenotypic variances. The chromosomal positions of the 10 QTLs overlapped with those of previously reported QTLs, whereas the targeted traits varied. Our QTLs will aid future breeding programs in improving growth and meat yield of chickens (e.g., via marker-assisted selection), particularly in the Japanese brand chicken industry.

Quantitative trait loci mapping for the shear force value in breast muscle of F2 chickens.

The shear force value is one of the major traits that determine meat quality. In the present study, we performed QTL analysis for chicken breast muscle shear force value at 7 wk of age using 545 single nucleotide polymorphism (SNP) markers developed via restriction-site associated DNA sequencing (RAD-seq). An F2 resource family was generated by mating Oh-Shamo, a native Japanese chicken breed, and the White Plymouth Rock chicken breed. A total of 215 F2 birds were produced. Simple interval mapping revealed one significant main-effect QTL between 6.28 and 8.10 Mb SNPs on the chromosome Z with a logarithm of odds score of 5.53 at the genome-wide 5% level. At this QTL, the confidence interval, phenotypic variance explained, and additive effect were 26 cM, 12.24%, and -0.31 in males and -0.34 in females, respectively. No QTL with epistatic interaction effects were detected. To our knowledge, this is the first report on a QTL affecting the shear force value in the chicken breast muscle, using SNP markers derived from RAD-seq.

Expression patterns of gdnf and gfrα1 in rainbow trout testis.

In mice, glial cell line-derived neurotrophic factor (GDNF) is essential for normal spermatogenesis and in vitro culture of spermatogonial stem cells. In murine testes, GDNF acts as paracrine factor; Sertoli cells secrete it to a subset of spermatogonial cells expressing its receptor, GDNF family receptor α1 (GFRα1). However, in fish, it is unclear what types of cells express gdnf and gfrα1. In this study, we isolated the rainbow trout orthologues of these genes and analyzed their expression patterns during spermatogenesis. In rainbow trout testes, gdnf and gfrα1 were expressed in almost all type A spermatogonia (ASG). Noticeably, unlike in mice, the expression of gdnf was not observed in Sertoli cells in rainbow trout. During spermatogenesis, the expression levels of these genes changed synchronously; gdnf and gfrα1 showed high expression in ASG and decreased dramatically in subsequent developmental stages. These results suggested that GDNF most likely acts as an autocrine factor in rainbow trout testes.

Effects of a chicken collagen hydrolysate on the circulation system in subjects with mild hypertension or high-normal blood pressure.

We investigated the effects of a chicken collagen hydrolysate (CCH) on the circulation system in humans. A total of 58 subjects with either mild hypertension (systolic blood pressure (SBP) of 140-159 mmHg or diastolic blood pressure (DBP) 90-99 mmHg) or high-normal blood pressure (SBP 130-139 mmHg or DBP 85-89 mmHg) were assigned to two groups, one involving a placebo and the other, the test food (including CCH of 2.9 g/d). The parameters related to each subject's circulation system were monitored over the study period of 18 weeks. The Δbrachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness and marker of vascular damage, was significantly lower in the test food group than in the placebo group during the treatment period. The blood pressure in the test food group was also significantly lower than that in the placebo group, while the serum nitrogen oxide was higher in the test food group after the treatment. These results suggest that CCH exerted modulatory effects on the human circulation system.

Chicken collagen hydrolysate reduces proinflammatory cytokine production in C57BL/6.KOR-ApoEshl mice.

Effects of chicken collagen hydrolysate (CCH) on atherogenesis in apolipoprotein E-deficient C57BL/6.KOR-ApoE(shl) mice were investigated in this paper. The mice were fed on either a normal CE-2 diet (control group) or a diet containing 10% CCH (CCH group) for 12 wk. Compared with that of the control, the amount of total plasma cholesterol, total hepatic cholesterol and hepatic triglycerides in the CCH group was reduced by 14.4, 24.7 and 42.8%, respectively. Histological analysis results showed that the abundance of diffuse hepatic lipid droplets and fat vacuoles was decreased in the CCH group. Meanwhile, the concentration of proinflammatory cytokines in the CCH group plasma, including interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1), and tumor necrosis factor-alpha (TNF-alpha), was downregulated by 43.4, 17.9 and 24.1%, respectively. The present results suggested that CCH treatment might help prevent atherosclerosis through not only its lipid-lowering effects but also inhibiting expression of inflammatory cytokines.

Molecular size of collagen peptide reverses the permeability of Caco-2 cells.

Intestinal permeability to size-classified fish collagen peptides (FCPs) was examined using Caco-2 monolayers. Minimum-sized FCPs were most efficiently transported across the Caco-2 monolayers. Permeability depended on peptide size. It was independent of the H(+)-coupled peptide transport system but was associated with tight junction permeability, suggesting that the paracellular pathway is responsible for transepithelial transport of collagen peptides.

The bioavailable octapeptide Gly-Ala-Hyp-Gly-Leu-Hyp-Gly-Pro stimulates nitric oxide synthesis in vascular endothelial cells.

Gly-Ala-Hyp-Gly-Leu-Hyp-Gly-Pro (GAXGLXGP, X: Hyp), an octapeptide contained in chicken collagen hydrolysate, inhibits angiotensin I-converting enzyme activity in vitro. Intestinal Caco-2 and bovine aortic endothelial cells (BAECs) were used to investigate whether the transported GAXGLXGP improves vascular function. When GAXGLXGP was added to the apical side of Caco-2 monolayers, the intact form of GAXGLXGP was released to the basolateral side without incorporation into the cells. This transport was energy-independent but was associated with tight junction permeability. GAXGLXGP was then added to BAECs, and endothelial nitric oxide (NO) synthase (eNOS) activation was examined. GAXGLXGP at a concentration of 10 microM stimulated production of NO during a 1 h incubation. This event involved phosphorylation of eNOS at Ser(1179) without a change in the total eNOS protein level. These findings indicate that GAXGLXGP absorbed intact through the intestinal epithelium has direct effects on eNOS activity in vascular endothelial cells, leading to NO synthesis, thereby suggesting the potential for improvement in vascular function.

Chicken collagen hydrolysate protects rats from hypertension and cardiovascular damage.

We previously reported that chicken collagen hydrolysate (CCH) has strong angiotensin I converting enzyme (ACE) inhibitory activity and antihypertensive effects on spontaneously hypertensive rats. Here, we investigated the chronic therapy effects of CCH on blood pressure and vascular relaxation in a cardiovascular damage model of Wistar-Kyoto rats induced by N-nitro-l-arginine methyl ester (L-NAME). Following co-treatment with CCH for 4 weeks, the increment of systolic blood pressure was suppressed significantly. At 8 weeks, the vasorelaxation of thoracic aorta increased significantly, and cardiovascular damage was ameliorated. The concentration of soluble intercellular adhesion molecule-1 (ICAM-1) in blood was reduced significantly by long-term administration of CCH, whereas the nitric oxide concentration was increased significantly at 1 hour post-treatment. The results suggest that beneficial effects of CCH result from antihypertensive function, but also from inhibition of cardiovascular damage to the endothelial cells via its ACE inhibitory activity and regulation of nitric oxide and ICAM-1, which suggests that CCH may be useful as a medicinal food for patients with cardiovascular disease.