The contribution of microbial necromass to soil organic carbon and influencing factors along a variation of habitats in alpine ecosystems.

A growing consensus is reached that microbes contributes to regulating the formation and accumulation of soil organic carbon (SOC). Nevertheless, less is known about the role of soil microbes (necromass, biomass) in SOC accumulation in different habitat conditions in alpine ecosystems. To address this knowledge gap, the composition and distribution of amino sugars (ASs) and phospholipid fatty acids (PLFAs) as biomarkers of microbial necromass and biomass were investigated in forest, meadow and wetland soil profile (0-40 cm) of Mount Segrila, Tibet, China, as well the contribution of bacterial and fungal necromass to SOC. The results revealed that microbial necromass carbon contributed 45.15 %, 72.51 % and 78.08 % on average to SOC in 0-40 cm forest, meadow and wetland soils, respectively, and decreased with microbial biomass. Fungal necromass contributed more to SOC in these habitats than bacterial necromass. Microbial necromass increased with microbial biomass and both of them decreased with soil depth in all habitats. The necromass accumulation coefficient was significantly correlated with microbial necromass and biomass, affected by habitat and soil moisture. Structural equation model indicated that soil abiotic factors indirectly mediated the accumulation of SOC through microbial necromass and biomass. This study revealed that different habitats and soil depths control considerably soil physicochemical properties and microbial community, finally influencing SOC accumulation in alpine ecosystems, which emphasized the influence of abiotic factors on microbial necromass and biomass for SOC accumulation in alpine ecosystems.

Potential protective effect of hesperidin on hypoxia/reoxygenation-induced hepatocyte injury.

Hesperidin (HDN) has been reported to have hydrogen radical- and hydrogen peroxide-removal activities and to serve an antioxidant role in biological systems. However, whether HDN protects hepatocytes (HCs) against hypoxia/reoxygenation (H/R)-induced injury remains unknown. The present study aimed to explore the role of HDN in H/R-induced injury. HCs were isolated and cultured under H/R conditions with or without HDN treatment. HC damage was markedly induced under H/R, as indicated by cell viability, supernatant lactate dehydrogenase levels and alanine aminotransferase levels; however, HDN treatment significantly reversed HC injury. Oxidative stress markers (malondialdehyde, superoxide dismutase, glutathioneand reactive oxygen species) were increased markedly during H/R in HCs; however, this effect was significantly attenuated after exposure to HDN. Compared with those of the control group, the mRNA expression levels of IL-6 and TNF-α in HCs and the concentrations of IL-6 and TNF-α in the supernatants increased significantly following H/R, and HDN significantly ameliorated these effects. Western blotting demonstrated that microtubule-associated protein 1 light chain 3α (MAP1LC3A, also known as LC3) and Beclin-1 protein expression levels increased, while sequestosome 1 levels decreased during H/R following exposure to HDN. The number of GFP-LC3 puncta in HCs following exposure to HDN was increased compared with that observed in HCs without HDN exposure under the H/R conditions after bafilomycin A1 treatment. In summary, the present study demonstrated that HDN attenuated HC oxidative stress and inflammatory responses while enhancing autophagy during H/R. HDN may have a potential protective effect on HCs during H/R-induced injury.

IL-17 is a potential biomarker for predicting the severity and outcomes of pulmonary contusion in trauma patients.

Pulmonary contusion (PC) is very common in blunt chest trauma, and always results in negative pulmonary outcomes, such as pneumonia, acute respiratory distress syndrome (ARDS), respiratory failure or even death. However, there are no effective biomarkers which can be used to predict the outcomes in these patients. The present study aimed to determine the value of interleukin (IL)-17 and IL-22 in predicting the severity and outcomes of PC in trauma patients. All trauma patients admitted to The First Affiliated Hospital of Guangxi Medical University between January 2015 and December 2017, were studied. Patients aged >14 years old with a diagnosis of PC upon their admission to the emergency department were included. Patients with PC were enrolled as the PC group, patients without PC were enrolled as the non-PC group, and healthy individuals were selected as the control group. Clinical information, including sociodemographic parameters, clinical data, biological findings and therapeutic interventions were recorded for all patients who were enrolled. Blood samples were collected and stored according to the established protocols. PC volume was measured by computed tomography and plasma cytokine levels were assayed by ELISA. A total of 151 patients with PC (PC group) and 159 patients without PC (non-PC group) were included in the present study. In addition, 50 healthy individuals were used as the control group. The primary cause of PC was motor vehicle crashes. PC patients had more rib fractures, but similar injury severity scores compared with other patients. More patients received Pleurocan drainage treatment and had pneumonia complications in the PC group compared with the other two groups. PC patients had a high incidence of ARDS and admission to the intensive care unit (ICU). PC patients also experienced longer periods on mechanical ventilation and had longer stays in the ICU and hospital. PC volume was effective in predicting the outcomes of PC patients. IL-22 levels were similar in the PC group and non-PC group. However, IL-17 could be used as a biomarker to predict the severity of PC, and was strongly associated with PC volume. IL-17 was significantly associated with pro-inflammatory complications in PC patients and could be used as a biomarker for predicting in-patient outcomes of patients with PC. In conclusion, IL-17 is a potential biomarker for predicting the severity and outcomes of PC in trauma patients.

Hesperidin ameliorates liver ischemia/reperfusion injury via activation of the Akt pathway.

Hesperidin (HDN) is a bioflavonoid that serves a role as an antioxidant in biological systems. However, although HDN has hydrogen radical­ and hydrogen peroxide­removal activities, the role of HDN in liver ischemia/reperfusion (I/R) injury remains unknown. This study aimed to determine the role of HDN in liver I/R injury. Male C57BL/6J wild­type (WT) mice were subjected to warm partial liver I/R injury. Liver damage was evaluated by measuring serum alanine aminotransferase (ALT) levels, cytokine production, oxidative stress indicators, tissue hematoxylin­eosin staining and cell death. The Akt signaling pathway was examined to elucidate the underlying mechanisms. HDN had no effect on ALT levels and tissue damage in WT mice without liver I/R injury. However, HDN significantly ameliorated liver I/R injury as measured by serum ALT levels and necrotic tissue areas. HDN decreased malondialdehyde content, but increased the levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione. In addition, HDN significantly attenuated the mRNA expression levels of TNF­α, IL­6 and IL­1ß after liver I/R injury. Furthermore, HDN protected the liver against apoptosis in liver I/R injury by increasing the levels of Bcl­2 and decreasing the levels of cleaved­caspase 3. Mechanistically, the levels of phosphorylated Akt were elevated by HDN during liver I/R injury. In addition, HDN could induce Akt activation in hepatocytes in vitro. Most importantly, treatment with the Akt inhibitor LY294002 in WT mice blocked the hepatoprotective effects of HDN in liver I/R injury. In summary, the results of the present study suggested that HDN may protect against liver I/R injury through activating the Akt pathway by ameliorating liver oxidative stress, suppressing inflammation and preventing hepatocyte apoptosis. HDN may be a useful factor for liver injury protection and a potential therapeutic treatment for liver I/R injury in the future.

Cathepsin S silencing induces apoptosis of human hepatocellular carcinoma cells.

This study was to investigate the potential molecular mechanisms underlying the Cathepsin S (CTSS) silencing induced apoptosis of Hepatocellular Carcinoma (HCC) cells with lentivirus-mediated RNA interference. Real-time quantitative PCR and western blot assay were performed to detect the mRNA and protein expression of CTSS, respectively, in 13 HCC cell lines with different metastatic potentials. Results showed MHCC97-H cells had the highest CTSS expression. Therefore, MHCC97-H cells were used in following experiments. Then, lentivirus-mediated RNAi was employed to silence CTSS expression (shCTSS). Annexin V/FITC staining showed NF-κB was activated in shCTSS cells treated with conditioned medium from shCTSS-PAR2 cells. This implies a probable positive correlation between PAR2 and CTSS. In addition, results demonstrated CTSS induced apoptosis of HCC cells and increased their chemosensitivity via regulating NF-κB and activating cleaved caspase-3. Our results indicate that CTSS silencing by lentivirus mediated RNAi can significantly induce apoptosis and chemosensitivity of MHCC97-H cells. This provides an attractive anti-cancer strategy and a novel strategy for the treatment of human HCC.

[Distribution pattern of Rhododendron aganniphum var. schizopeplum population at the timberline of Sejila Mountains, Tibet of China].

Rhododendron aganniphum var. schizopeplum grows at the elevation of 4300-4500 m in Sejila Mountains, being a dominant species of shrub layer at the timberline of southeast Tibet. Based on the sampling plot investigation and basal diameter structure analysis, this paper studied the distribution pattern of R. aganniphum var. schizopeplum population at the timberline of Sejila Mountains. With the increase of altitude, the population density of R. aganniphum var. schizopeplum increased, but the population height decreased. At the same altitudes, the population density on the shady slope was larger than that on the sunny slope, while the basal diameter was smaller. On the two slope directions, the distribution of the basal diameter classes of the population appeared as "(see text for symbol)" shape, i. e., middle-aged individuals were more, while seedlings and saplings were relatively less. The intraspecific competition of R. aganniphum var. schizopeplum population was in the form of wave, being stronger on shady slope than on sunny slope, and existing self-thinning.

[Characteristics of soil nematode community in Abies georgei var. smithii forest gaps in south-east Tibet, China].

In order to understand the characteristics of soil nematode community in the Abies georgei var. smithii forest gaps in southeast Tibet, an investigation was conducted to study the variations of soil nematode community at different depths of 0-30 cm soil layer in the gaps and non-gaps. The nematode individual density, diversity index, and trophic group index were taken to analyze the composition and structural characteristics of the soil nematode community. A total of 26801 soil nematodes belonging to 2 classes, 5 orders, and 64 genera were collected by shallow dish method. The nematode individual density was averagely 3552 ind x 100 g(-1) dry soil, and the individuals had a highly surface-gathering characteristics. In the gap soils, the dominant genera were Tylencholaimus and Filenchus, while the dominant trophic group was bacterivores. The soil organic matter was decomposed by both bacteria and fungi. The ecological index results showed that the nematodes diversity and richness were related to gap size. The characteristics of soil nematode community in the gaps were different from those in closed stand and forest open land, and this difference indicated the potential for using nematodes as the environmental indicator species.

[Community characteristics of soil nematode in Abies georgei var. smithii forest in Sejila Mountain of Tibet, Southwest China].

In order to understand the present status of nematode diversity in soil ecosystem of Abies georgei var. smithii forest, the typical forest type in subalpine zone of southeastern Tibet, an investigation was made on the nematode community in different soil layers of 0-30 cm depth from the summer, 2010 to the spring, 2011. The nematode individual density, diversity index, and trophic group index were taken to analyze the composition and structural characteristics of the soil nematode community. A total of 7915 soil nematodes belonging to 2 classes, 6 orders, 38 families, and 67 genera were collected by shallow dish method. The nematode individual density was averagely 620 nematodes x 100 g(-1) dry soil, and the nematode individuals in surface soil layer (0-5 cm) accounted for 56.9% of the total, indicating the obvious surface gathering characteristics of the nematode community. Tylencholaimus, Helicotylenchus, and Plectus were the dominant genus. Plant-parasite nematode was the dominant trophic group, while fungi-feeding nematode had the largest proportion among the non plant-parasite nematodes. Soil organic matter was mainly decomposed by fungi. The ANOVA analysis indicated that there were no significant differences in the Shannon, Pielou, Margalef, and Simpson indices of soil nematode community among different seasons. The Pielou index had no significant difference among different soil layers, while the differences of Shannon, Margalef, and Simpson indices tended to be increased with increasing soil depth. It was concluded that the A. georgei var. smithii forest ecosystem in Sejila Mountain had a high maturity, with strong resistance to environment disturbances.

[Biomass and yield of Betula platyphylla population in Mila Mount of Tibet].

Mila Mount in Southeast Tibet is the west boundary of the horizontal distribution of Betula platyphylla. It is also the highest altitude area in China and the world, where Betula platyphylla is distributed. Based on the investigation of regional sample plots and the analysis of analytic trees, this paper compared the biomass and yield of Betula platyphylla population at different slope orientation and different altitude. The results showed that the growth of Betula platyphylla was greatly interfered by human activities. The yearly productivity of Betula platyphylla grown in Mila Mount was 363.1-2,072.94 kg x hm(-2), and the biomass was 7,625.00-33,167.00 kg x hm(-2), indicating that the biomass of Betula platyphylla was quite different for different population. The productivity and biomass of Betula platyphylla coppice after cutting were lower than those of seedling forest, and there existed youth broken-down in the coppice. The zonal changes of water resources had no significant effect on the water allocation and the biomass of Betula platyphylla.

[Effects of gap in primitive subalpine fir forest on diversity of herb and shrub in Tibet].

Effects of gap in primitive fir forest in southeast Tibet on species diversity of herb and shrub were studied. The results showed that species composition, distribution and diversity in gap were different from those in non-gap. The improvement of illumination and other habitat conditions resulted in richer species of herb and shrub in gap. There were shade-tolerant and photophilic herb species and shrub species in gap, however, only shade-tolerant herb species and shrub species grew in non-gap. Species diversity and evenness in gap were higher than in non-gap. The diminutive similar coefficient between herb and shrub communities showed that certain difference existed between herb and shrub communities in stands of gap and non-gap. The similar coefficients were little correlative between gap area and communities. Gap was important to improve growth of herb and shrub and maintain species diversity of primitive subalpine fir forest in southwest Tibet.

[Characteristics and disturbance status of gaps in subalpine fir forest in southeast Tibet].

Characteristics and disturbance status of gaps, including gap size, disturbance frequency, forming patterns of gaps, and quantity of the tree in gap, in subalpine fir forest in Southeast Tibet were studied. The results showed that expanded gaps accounted for 41.73% and canopy gaps accounted for 14.71% of land area in the forest. Averagely, 0.82% and 0.29% of forest area were transformed into expanded and canopy gaps every year. The velocity of gap forming was 0.31 ind.hm-2.yr-1. The disturbance cycle of gaps was 345 yr. Among 16 investigated gaps, there were 78 gap-markers in total, and there were averagely 4.88 trees in each gap. The main reasons of gap forming were gap-markers fallen as well as uprooted and withered, and their external force was strong wind. The possibility of gaps forming reached the maximum while the diameter of arbors was 40-60 cm and the high was 15-20 m in the main forest layer. Gaps were formed by many disturbances in different age in the subalpine fir forest in Southeast Tibet..