RESUMO
Exploring the temperature sensitivity of leaf dark respiration is of significance for understanding forest carbon cycling and its response to climate change. However, its intra-specific variability and seasonality are not clear yet. In this study, we measured the temperature sensitivity coefficient (Q10) of leaf dark respiration for Dahurian larch (Larix gmelinii) that were transplanted from four latitudinal sites (i.e., Tahe, Songling, Heihe, and Dailing) in a common garden. Our specific aims were to explore the seasonal dynamics of Q10 and compare differences in Q10 among the indivi-duals from the four latitudinal sites. The results showed that the Q10 for the four sites exhibited similar seasonal trend, with the maximum Q10 in the middle growing season. The inter-site difference in Q10 was significant, ranging from (1.48±0.01) to (2.15±0.03). Furthermore, the inter-site difference showed the same pattern across the whole growing season, i.e., the warmer and lower latitudinal sites, the higher Q10. The Q10 was significantly and positively correlated with foliar nitrogen concentration and soluble sugar concentration, and mean annual temperature and mean annual precipitation in the transplanting sites. These findings suggested that the inter-site variation in Q10 and its seasonality could be mainly attributed to the foliar nutrient concentration and adaptation of trees to the climatic conditions of the transplanting sites, which should be considered in modeling and predicting responses of forest carbon cycling to climate change.
Assuntos
Agricultura Florestal/métodos , Larix , Folhas de Planta/metabolismo , Florestas , Temperatura , ÁrvoresRESUMO
<p><b>AIM</b>To develop a method for assessing sperm function by measuring released acrosin activity during the acrosome reaction (AR).</p><p><b>METHODS</b>Human semen samples were obtained from 24 healthy donors with proven fertility after 3-7 days of sexual abstinence. After collection, samples were liquefied for 30 min at room temperature. Standard semen parameters were evaluated according to World Health Organization (WHO) criteria. Calcium ionophore A23187 and progesterone (P4) were used to stimulate the sperm to undergo AR. After treatment, sperm were incubated with the supravital dye Hoechst33258, fixed in a glutaraldehyde-phosphate-buffered saline solution, and the acrosomal status was determined by fluorescence microscopy with fluorescein isothiocyanate-labeled Pisum sativum agglutinin (FITC-PSA). The percentage of sperm undergoing AR (AR%) was compared to sperm acrosin activities as assessed by spectrocolorimetry. The correlation between AR% and acrosin activity was determined by statistical analysis.</p><p><b>RESULTS</b>The AR% and released acrosin activity were both markedly increased with A23187 and P4 stimulation. Sperm motility and viability were significantly higher after stimulation with P4 versus stimulation with A23187 (P < 0.001). There was a significant positive correlation between released acrosin activity and AR% determined by FITC-PSA staining (r=0.916, P < 0.001).</p><p><b>CONCLUSION</b>Spectrocolorimetric measurement of released acrosin activity might serve as a reasonable alternative method to evaluate AR.</p>
