Characterisation of a novel quantitative trait locus, GN4-1, for grain number and yield in rice (Oryza sativa L.).

KEY MESSAGE: A novel QTL for grain number, GN4-1, was identified and fine-mapped to an ~ 190-kb region on the long arm of rice chromosome 4. Rice grain yield is primarily determined by three components: number of panicles per plant, grain number per panicle and grain weight. Among these traits, grain number per panicle is the major contributor to grain yield formation and is a crucial trait for yield improvement. In this study, we identified a major quantitative trait locus (QTL) responsible for rice grain number on chromosome 4, designated GN4-1 (a QTL for Grain Number on chromosome 4), using advanced segregating populations derived from the crosses between an elite indica cultivar 'Zhonghui 8006' (ZH8006) and a japonica rice 'Wuyunjing 8' (WYJ8). GN4-1 was delimited to an ~ 190-kb region on chromosome 4. The genetic effect of GN4-1 was estimated using a pair of near-isogenic lines. The GN4-1 gene from WYJ8 promoted accumulation of cytokinins in the inflorescence and increased grain number per panicle by ~ 17%. More importantly, introduction of the WYJ8 GN4-1 gene into ZH8006 increased grain yield by ~ 14.3 and ~ 11.5% in the experimental plots in 2014 and 2015, respectively. In addition, GN4-1 promoted thickening of the culm and may enhance resistance to lodging. These results demonstrate that GN4-1 is a potentially valuable gene for improvement of yield and lodging resistance in rice breeding.

Postmyocardial infarction remodeling and coronary reserve: effects of ivabradine and beta blockade therapy.

We compared the effects of heart rate reduction (HRR) by the hyperpolarization-activated pacemaker current (I(f)) channel inhibitor ivabradine (MI+Iva) and the beta(1)-blocker atenolol (MI+Aten) on ventricular remodeling and perfusion after myocardial infarction (MI) in middle-aged (12 mo) Sprague-Dawley rats. Mean HRR was virtually identical in the two treated groups (19%). Four weeks after coronary artery ligation, maximal myocardial perfusion fell in the MI group but was preserved in infarcted rats treated with either Iva or Aten. However, coronary reserve in the remodeled hearts was preserved only with Iva, since Aten treatment elevated baseline perfusion in response to a higher wall stress. The higher maximal perfusion noted in the two treated groups was not due to arteriogenesis or angiogenesis. Plasma levels of angiotensin (ANG) II and myocardial ANG type 1 (AT(1)) receptor and transforming growth factor (TGF)-beta1 were reduced during the first week of treatment by both Iva and Aten. Moreover, treatment also reduced arteriolar perivascular collagen density. Despite these similar effects of Iva and Aten on vascularity and ANG II, Iva, but not Aten, attenuated the decline in ejection fraction and lowered left ventricular (LV) end-diastolic volume (LVEDV)-to-LV mass ratio, determined by echocardiography. In conclusion, 1) Iva has advantages over Aten in postinfarction therapy that are not due to differential effects of the drugs on heart rate, and 2) age limits growth factor upregulation, angiogenesis, and arteriogenesis in the postinfarcted heart.

Characterization of circulating CD8+T cells expressing skin homing and cytotoxic molecules in active non-segmental vitiligo.

BACKGROUND: Vitiligo is caused by melanocyte depletion. Studies have suggested that skin-homing cytotoxic T lymphocytes that express cutaneous lymphocyte-associated antigen (CLA) are responsible for melanocyte depletion. The characteristics of these skin-homing cytotoxic T cells have not been well established yet. OBJECTIVES: To investigate the frequency of skin-homing CD8(+)T cells (CD8(+)CLA(+)T cells) and their expression of cytotoxic molecules, as well as migration-related molecules in CD8(+)T cell in non-segmental vitiligo patients. MATERIALS & METHODS: The frequency of CD8(+)CLA(+)T cells and their expression of cytotoxic molecules (perforin, granzyme-B and FasL) in peripheral blood of patients with non-segmental vitiligo were assessed using flow cytometry. Levels of chemokine receptors (CCR4, CCR10) on CD8(+)T cells were evaluated. RESULTS: Our results revealed a higher frequency and increased expression of perforin and granzyme-B in circulating CD8(+)CLA(+)T cells from patients with active vitiligo. The expression levels of CCR4 increased in CD8(+)T cells in active vitiligo patients. CONCLUSION: Patients with active non-segmental vitiligo have a higher frequency of CD8(+)CLA(+)T cells and hyper-activated cytotoxic functions, which may be involved in the pathogenesis of non-segmental vitiligo.