Effect of permafrost degradation on carbon sequestration of alpine ecosystems.

Permafrost degradation profoundly affects carbon storage in alpine ecosystems, and the response characteristics of carbon sequestration are likely to differ at the different stages of permafrost degradation. Furthermore, the sensitivity of different stages of permafrost degradation to climate change is likely to vary. However, related research is lacking so far on the Qinghai-Tibetan Plateau (QTP). To investigate these issues, the Shule River headwaters on the northeastern margin of the QTP was selected. We applied InVEST and Noah-MP land surface models in combination with remote sensing and field survey data to reveal the dynamics of different carbon (vegetation carbon, soil organic carbon (SOC), and ecosystem carbon) pools from 2001 to 2020. A space-for-time analysis was used to explore the response characteristics of carbon sequestration along a gradient of permafrost degradation, ranging from lightly degraded permafrost (H-SP) to severely degraded permafrost (U-EUP), and to analyze the sensitivity of the permafrost degradation gradient to climate change. Our results showed that: (1) the sensitivity of mean annual ground temperature (MAGT) to climatic variables in the U-EUP was stronger than that in the H-SP and S-TP, respectively; (2) rising MAGT led to permafrost degradation, but increasing annual precipitation promoted permafrost conservation; (3) vegetation carbon, SOC, and ecosystem carbon had similar spatial distribution patterns, with their storage decreasing from the mountain area to the valley; (4) alpine ecosystems acted as carbon sinks with the rate of 0.34 Mg‧ha-1‧a-1 during 2001-2020, of which vegetation carbon and SOC accumulations accounted for 10.65 % and 89.35 %, respectively; and (5) the effects of permafrost degradation from H-SP to U-EUP on carbon density changed from promotion to inhibition.

[Spatial and Temporal Variations in Spectrum-Derived Vegetation Growth Trend in Qinghai-Tibetan Plateau from 1982 to 2014].

Recently considerable researches have focused on monitoring vegetation changes because of its important role in regula- ting the terrestrial carbon cycle and the climate system. There were the largest areas with high-altitudes in the Qinghai-Tibet Plateau (QTP), which is often referred to as the third pole of the world. And vegetation in this region is significantly sensitive to the global warming. Meanwhile NDVI dataset was one of the most useful tools to monitor the vegetation activity with high spatial and temporal resolution, which is a normalized transform of the near-infrared radiation (NIR) to red reflectance ratio. Therefore, an extended GIMMS NDVI dataset from 1982-2006 to 1982-2014 was presented using a unary linear regression by MODIS dataset from 2000 to 2014 in QTP. Compared with previous researches, the accuracy of the extended NDVI dataset was improved again with consideration the residuals derived from scale transformation. So the model of extend NDVI dataset could be a new method to integrate different NDVI products. With the extended NDVI dataset, we found that in growing season there was a statistically significant increase (0.000 4 yr⁻¹, r² = 0.585 9, p < 0.001) in QTP from 1982 to 2014. During the study pe- riod, the trends of NDVI were significantly increased in spring (0.000 5 yr⁻¹, r² = 0.295 4, p = 0.001), summer (0.000 3 yr⁻¹, r² = 0.105 3, p = 0.065) and autumn respectively (0.000 6 yr⁻¹, r² = 0.436 7, p < 0.001). Due to the increased vegeta- tion activity in Qinghai-Tibet Plateau from 1982 to 2014, the magnitude of carbon sink was accumulated in this region also at this same period. Then the data of temperature and precipitation was used to explore the reason of vegetation changed. Although the trends of them are both increased, the correlation between NDVI and temperature is higher than precipitation in vegetation grow- ing season, spring, summer and autumn. Furthermore, there is significant spatial heterogeneity of the changing trends for ND- VI, temperature and precipitation at Qinghai-Tibet Plateau scale.

[Effects of plant density and nitrogen level on nitrogen uptake and utilization of winter wheat].

A two-year (2011-2012 and 2012-2013) field experiment was conducted on one winter wheat cultivar supplied with two levels, of nitrogen (180 and 240 kg N · hm(-2)) under three plant densities (135 x 10(4), 270 x 10(4), and 405 x 10(4) plants · hm(-2)) . The 15N-labeled urea was injected into 20, 60 and 100 cm soil depths, respectively, aiming to investigate the effect of nitrogen and plant density and their interaction on the N uptake, utilization and nitrate nitrogen contents at different soil depths. The results showed that increasing the plant density from 135 x 10(4) to 405 x 10(4) plants · hm(-2) significantly increased the 15N uptake at depths of 20, 60 and 100 cm averagely by 1.86, 2.28 and 2.51 kg · hm(-2), respectively, and increased the above ground N uptake (AGN) , N uptake efficiency (UPE) averagely by 12.6% and 12.6%, respectively, but decreased the N utilization efficiency (UTE) by 5.4%. Compared to the N input of 240 kg N · hm(-2) the 180 kg N · hm(-2) significantly reduced the 15N uptake at depths of 20 and 60 cm averagely by 4. 11 and 1.21 kg · hm(-2), respectively, and significantly increased the 15N uptake at depths of 100 cm averagely by 1.02 kg · hm(-2). Reducing the N input decreased the AGN averagely by 13.5%, but significantly increased the UPE and UTE by 9.4% and 12.2%, respectively. Equivalent grain yield was observed among N input of 180 kg N · hm(-2) with plant density of 405 x 10(4) plants · hm(-2) and N input of 240 kg N · hm(-2) with plant densities of 270 x 10(4) and 405 x 10(4) plants · hm(-2). Increasing the plant density or reducing the N input could encourage the N uptake at deep soil profile and increased UPE and UTE by 13.4% and 11.9%, respectively. Meanwhile, both the nitrate nitrogen contents in 0-200 cm soil layers at maturity and the ratio of the nitrate nitrogen in 100-200 cm soil layers to that in -200 cm were significantly decreased. Therefore, properly decreasing the N input with increasing the plant density of winter wheat was efficient in absorbing N at deep soil, synergistically obtaining high grain yield, UPE and UTE, and reducing the pollution of residual soil nitrate.

Decrease in fertilization and cleavage rates, but not in clinical outcomes for infertile men with AZF microdeletion of the Y chromosome.

This study aimed to explore whether the presence of a Y chromosome azoospermia factor (AZF) microdeletion confers any adverse effect on embryonic development and clinical outcomes after intracytoplasmic sperm injection (ICSI) treatment. Fifty-seven patients with AZF microdeletion were included in the present study and 114 oligozoospermia and azoospermia patients without AZF microdeletion were recruited as controls. Both AZF and control groups were further divided into subgroups based upon the methods of semen collection: the AZF-testicular sperm extraction subgroup (AZF-TESE, n = 14), the AZF-ejaculation subgroup (AZF-EJA, n = 43), the control-TESE subgroup (n = 28) and the control-EJA subgroup (n = 86). Clinical data were analyzed in the two groups and four subgroups respectively. A retrospective case-control study was performed. A significantly lower fertilization rate (69.27 versus 75.70%, P = 0.000) and cleavage rate (89.55 versus 94.39%, P = 0.000) was found in AZF group compared with the control group. Furthermore, in AZF-TESE subgroup, the fertilization rate (67.54 versus 74.25%, P = 0.037) and cleavage rate (88.96 versus 94.79%, P = 0.022) were significantly lower than in the control-TESE subgroup; similarly, the fertilization rate (69.85 versus 75.85%, P = 0.004) and cleavage rate (89.36 versus 94.26%, P = 0.002) in AZF-EJA subgroup were significantly lower than in the control-EJA subgroup; however, the fertilization rate and cleavage rate in AZF-TESE (control-TESE) subgroup was similar to that in the AZF-EJA (control-EJA) subgroup. The other clinical outcomes were comparable between four subgroups (P > 0.05). Therefore, sperm from patients with AZF microdeletion, obtained either by ejaculation or TESE, may have lower fertilization and cleavage rates, but seem to have comparable clinical outcomes to those from patients without AZF microdeletion.

Increased circulating Th1/Th2 ratios but not other lymphocyte subsets during controlled ovarian stimulation are linked to subsequent implantation failure after transfer of in vitro fertilized embryos.

PROBLEM: To investigate alterations of circulating lymphocyte subsets in women undergoing controlled ovarian stimulation (COS) and survey their relations with pregnancy outcome. METHOD OF STUDY: Fifty-one women were included in this study, of which 24 women were successfully pregnant in the index IVF cycle (the successful pregnancy group, sPG) and 27 women failed to get pregnant (the non-pregnancy group, nPG). Peripheral blood was collected at three time points during COS: on the day before the first GnRHa administration (GnRHa day), on the day before the first Gn administration (Gn day), and on the day before HCG administration (HCG day). The intracellular Th1(IFN-γ and TNF-α)/Th2(IL-10) ratios in circulating Th cells after in vitro phorbol-12-myristate-13-acetate stimulation, the NK cytotoxicity, and the percentage of T, B and NK cell subsets were assessed by flow cytometer. A third group consisting of patients with recurrent implantation failure (RIF group, n = 18) was also enrolled, and the intracellular Th1/Th2 ratios were assessed at HCG day. RESULTS: Intergroup comparison: The ratios of IFN-γ/IL-10 and TNF-α/IL-10 at HCG day were significantly higher (P < 0.05) in nPG than those in sPG, while no change at GnRHa day or Gn day. Higher (P < 0.05) ratios of IFN-γ/IL-10 and TNF-α/IL-10 at HCG day were also observed in RIF group compared to those in sPG. No significant change (P > 0.05) was found in other assessed lymphocyte subsets or in the concentrations of progesterone, estradiol, luteinizing hormone, or follicle-stimulating hormone between the sPG and nPG at the three time points. Intragroup comparison: The ratios of IFN-γ/IL-10 and TNF-α/IL-10 at HCG day were significantly (P < 0.05) lower than those at GnRHa day in sPG, but not in nPG. No significant (P > 0.05) difference was found in other assessed parameters or at other time points. CONCLUSIONS: The ratios of Th1/Th2 were fluctuated during COS, and they might affect the pregnancy outcome of IVF. The circulating NK cytotoxicity and percentage of lymphocyte subsets were relatively stable during the COS.

[Erythropoietin levels in patients with multiple sclerosis complicated with anemia].

OBJECTIVE: To explore the potential decrease of serum erythropoietin (EPO) level in patients with multiple sclerosis (MS) complicated with anemia. METHODS: The serum EPO levels were detected in the patients with MS complicated with anemia (MS group, n=31), patients with iron deficiency anemia (IDA group, n=33), and healthy subjects (normal control group, n=80) by enzyme-linked immunosorbent assay (ELISA). Blood routine test, reticulocyte count, hemoglobin, and indexes of liver and kidney function were also detected. RESULTS: The serum EPO level in MS group was significantly lower than those in IDA group [(101.3±17.6)U/L vs.(166.1±8.7)U/L, P<0.01]. Moreover, the serum EPO level decreased as the severity of anemia in the MS group increased: it was (95.7±9.6), (101.7±8.1), and (123.7±9.3) U/L in patients with mild, moderate, and severe anemia, respectively (P<0.05). Other indicators including blood routine findings, reticulocyte count, hemoglobin, and liver and kidney function parameters showed no significant difference between the MS group and the IDA group (P>0.05). CONCLUSIONS: The serum EPO level decreases in patients with multiple sclerosis complicated with anemia, and the decreasing levels are related with the severity of anemia. Thus EPO therapy may be beneficial for these patients.