High temperature-mediated disturbance of carbohydrate metabolism and gene expressional regulation in rice: a review.

Global warming has induced higher frequencies of excessively high-temperature weather episodes, which pose damage risk to rice growth and production. Past studies seldom specified how high temperature-induced carbohydrate metabolism disturbances from both source and sink affect rice fertilization and production. Here we discuss the mechanism of heat-triggered damage to rice quality and production through disturbance of carbohydrate generation and consumption under high temperatures. Furthermore, we provide strong evidence from past studies that rice varieties that maintain high photosynthesis and carbohydrate usage efficiencies under high temperatures will suffer less heat-induced damage during reproductive developmental stages. We also discuss the complexity of expressional regulation of rice genes in response to high temperatures, while highlighting the important roles of heat-inducible post-transcriptional regulations of gene expression. Lastly, we predict future directions in heat-tolerant rice breeding and also propose challenges that need to be conquered in the future.

Effects of hepatitis B virus on human semen parameters and sperm DNA integrity / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effects of hepatitis B virus (HBV) in semen on human semen parameters and sperm DNA integrity.</p><p><b>METHODS</b>We detected HBV DNA in the semen samples of 153 HBsAg-seropositive patients by real-time fluorescence quantitative PCR and calculated the sperm nuclear DNA fragmentation index (DFI) by sperm chromatin dispersion (SCD) assay. We compared the semen parameters between the HBV DNA-positive group (A, n = 43) and HBV DNA-negative group (B, n = 110) and analyzed the correlation of sperm DFI with the number of HBV DNA copies in the semen.</p><p><b>RESULTS</b>HBV DNA was detected in 43 (28.1%) of the 153 semen samples. No statistically significant differences were observed in age, semen volume and sperm concentration between groups A and B (P >0.05). Compared with group B, group A showed significantly decreased sperm viability ([58.0 +/- 18.8]% vs [51.4 +/-17.1]%, P<0.05), progressively motile sperm ([29.6 +/- 13.3]% vs [24.5 +/- 10.1]%, P<0.05), average straight-line velocity ([23.7 +/- 4.0] microm/s vs [19.9 +/- 4.5 ] microm/s, P<0.01) and average path velocity ([26.5 +/- 7.0] microm/s vs [23.4 +/- 5.3] microm/s, P<0.01), but remarkably decreased sperm DFI ([19.3 +/- 8.0]% vs [24.2 +/- 9.4]%, P<0.01). The number of HBV DNA copies in semen exhibited a significant positive correlation with sperm DFI (r = 0.819, P < 0.01).</p><p><b>CONCLUSION</b>HBV DNA in semen is not significantly associated with the number of sperm, but may affect sperm viability, velocity and DFI. There is a load-effect relationship between the number of HBV DNA copies in semen and sperm nuclear DNA integrity.</p>