Functional Groups Dominate Aboveground Net Primary Production under Long-Term Nutrient Additions in a Tibetan Alpine Meadow.

Anthropogenic nutrient additions are influencing the structure and function of alpine grassland ecosystems. However, the underlying mechanisms of the direct and indirect effects of nutrient additions on aboveground net primary productivity (ANPP) are not well understood. In this study, we conducted an eight-year field experiment to explore the ecological consequences of nitrogen (N) and/or phosphorous (P) additions on the northern Tibetan Plateau. ANPP, species diversity, functional diversity, and functional groups were used to assess species' responses to increasing nutrients. Our results showed that nutrient additions significantly increased ANPP due to the release in nutrient limitations. Although N addition had a significant effect on species richness and functional richness, and P and N + P additions altered functional diversity, it was functional groups rather than biodiversity that drove changes in ANPP in the indirect pathways. We identified the important roles of N and P additions in begetting the dominance of grasses and forbs, respectively. The study highlights that the shift of functional groups should be taken into consideration to better predict the structure, function, and biodiversity-ANPP relationship in grasslands, particularly under future multifaceted global change.

Winter warming alleviates the severely negative effects of nitrogen addition on ecosystem stability in a Tibetan alpine grassland.

Many recent studies have explored how global warming and increased nitrogen (N) deposition affect the structure and function of natural ecosystems. However, how ecosystems respond to the combination of warming and N enrichment remains unexplored, especially under asymmetric seasonal warming scenarios. We conducted a decade-long field experiment in an alpine grassland to investigate the effects of warming (ambient condition (NW), winter-only (WW), and year-round (YW) warming) and N addition on the temporal stability of communities. Although N addition significantly reduced community temporal stability in NW, WW, and YW, WW relieved the severely negative effects of N addition compared to NW and YW (from 47.7 % in NW and 76.1 % in YW to 18.6 % in WW under 80 kg N hm-2 year-1). The most remarkable finding is that the main factors driving community stability shifted with warming patterns. The increase in community dominance under NW was a significant driver of the decreased temporal stability in the community. However, the decrease in community stability caused by N addition was ascribed to the decreased stability of both dominant and common species under WW. In contrast, N addition decreased community temporal stability mainly via a decrease in species asynchrony under YW. Our results suggested that warming patterns can modulate the effects of N enhancement on community stability. To predict the effects of climate change on alpine grasslands accurately, the idiosyncratic effects of asymmetric seasonal warming under future climate change scenarios should be considered.

Variation of plant CSR strategies across a precipitation gradient in the alpine grasslands on the northern Tibet Plateau.

Identifying ecological strategies based on functional traits can help us better understand plants' adaptations and changes in ecological processes, and thus predict the impact of climate change on ecosystems, especially in the vulnerable alpine grasslands. Herein, we investigated the plant CSR strategies of four grassland types (alpine meadows, AM; alpine meadow steppes, AMS; alpine steppes, AS; and alpine desert steppes, ADS) and its functional groups (grasses, sedges, legumes, and forbs) along the east-to-west gradient of decreasing precipitation on the northern Tibetan grasslands by using Grime's CSR (C: competitor, S: stress tolerator, and R: ruderal) analysis. Although alpine grasslands were dominated by S-strategy, our results also indicated that AM with higher water, nitrogen (N) and phosphorus (P) availability had significantly lower S-strategy values and relatively higher C- and R-strategy values (C: S: R = 6: 63: 31 %) than those in AMS (C: S: R = 3: 94: 3 %,), AS (C: S: R = 3: 87: 10 %), and ADS (C: S: R = 1: 94: 5 %). The CSR strategy values of forbs and legumes showed greater variability compared with grasses and sedges in the environmental gradient. Furthermore, water variability on the precipitation gradient eventually affected plant traits and CSR strategies through soil N and P availability and pH. Our findings highlighted that plant CSR strategies were regulated by the availability of soil resources, and plants adopted more flexible adaptation strategies in relatively resource-rich environments. This study sheds light on the mechanisms of plant adaptation to the changing environment in the alpine grasslands.

Functional identity of leaf dry matter content regulates community stability in the northern Tibetan grasslands.

Biodiversity-stability mechanisms have been the focus of many long-term community stability studies. Community functional composition (i.e., functional diversity and functional identity of community plant functional traits) is critical for community stability; however, this topic has received less attention in large-scale studies. Here, we combined a field survey of biodiversity and plant functional traits in 22 alpine grassland sites throughout the northern Tibetan Plateau with 20 years of satellite-sensed proxy data (enhanced vegetation index) of community productivity to identify the factors influencing community stability. Our results showed that functional composition influenced community stability the most, explaining 61.71% of the variation in community stability (of which functional diversity explained 18.56% and functional identity explained 43.15%), which was a higher contribution than that of biodiversity (Berger-Parker index and species evenness; 35.04%). Structural equation modeling suggested that functional identity strongly affected community stability, whereas biodiversity had a minor impact. Furthermore, functional identity of leaf dry matter content regulated community stability by enhancing species dominance (Berger-Parker index). Our findings demonstrate that functional composition, specifically functional identity, plays a key role in community stability, highlighting the importance of functional identity in understanding and revealing the stabilizing mechanisms in these fragile alpine ecosystems which are subjected to increasing environmental fluctuations.

Community species diversity mediates the trade-off between aboveground and belowground biomass for grasses and forbs in degraded alpine meadow, Tibetan Plateau.

Although many empirical experiments have shown that increasing degradation results in lower aboveground biomass (AGB), our knowledge of the magnitude of belowground biomass (BGB) for individual plants is a prerequisite for accurately revealing the biomass trade-off in degraded grasslands. Here, by linking the AGB and BGB of individual plants, species in the community, and soil properties, we explored the biomass partitioning patterns in different plant functional groups (grasses of Stipa capillacea and forbs of Anaphalis xylorhiza). Our results indicated that 81% and 60% of the biomass trade-off variations could be explained by environmental factors affecting grasses and forbs, respectively. The change in community species diversity dominated the biomass trade-off via either direct or indirect effects on soil properties and biomass. However, the community species diversity imparted divergent effects on the biomass trade-off for grasses (scored at -0.72) and forbs (scored at 0.59). Our findings suggest that plant communities have evolved two contrasting strategies of biomass allocation patterns in degraded grasslands. These are the "conservative" strategy in grasses, in which plants with larger BGB trade-off depends on gigantic roots for soil resources, and the "opportunistic" strategy in forbs, in which plants can adapt to degraded lands using high variation and optimal biomass allocation.

Degradation shifts plant communities from S- to R-strategy in an alpine meadow, Tibetan Plateau.

The replacement of dominant sedges/grasses with secondary forbs is common in alpine rangelands, but the underlying plant ecological strategies and their relevance to leaf traits and their variabilities of different plant functional groups remain largely unknown. Here, we measured key leaf traits and analyzed the competitor, stress-tolerator and ruderal (CSR) strategies of major species with different functional groups (sedges, grasses and forbs) in an alpine meadow along a degradation gradient on the Tibetan Plateau. Our results indicated that S-selected species were dominant in both non-degraded (C:S:R = 1:95:4%) and severely degraded (C:S:R = 2:87:11%) meadows. However, there was a shift from S- to R-strategy in the communities after rangeland degradation. More specifically, sedges and grasses with a "conservative" strategy maintained stronger S-strategy to tolerate degraded and stressful conditions. In contrast, forbs with an "opportunistic" strategy (increase 9.5% in R-score) tended to adapt to degraded stages. Moreover, 51.1% and 23.9% of the increased R-scores in forbs were accounted by leaf mass per area and specific leaf area, respectively. Generally, higher leaf water and nitrogen contents coupled with larger variations in leaf traits and flexible SR strategies in forbs enabled them to capitalize on lower soil water and nutrient availability. Our findings highlighted that the contrasting strategies of plant species in response to the decrease in available resources might lead to niche expansion of secondary forbs and loss of diversity in the degraded alpine meadow. The emerging alternative stable states in the degraded rangelands might bring about a predicament for rangeland restoration.

Experimental Study and Clinical Observation on the Improvement Effect of Lienal Polypeptide on Blood Toxicity and Immune Injury Induced by Radiotherapy.

Aims: To investigate the immune and gastrointestinal functional effects of lienal polypeptide (LP) treatment in tumor-bearing mice and carcinoma patients receiving radiotherapy (RT), and to detect hematological indicators and T lymphocyte subsets. Methods: Tumor-bearing mice were randomly divided into five groups: the control group, the RT group, the RT+LP-L (1.7 mg/kg, low dosage of LP) group, the RT+LP-M (5.2 mg/kg, middle dosage of LP) group, and the RT+LP-H (10.4 mg/kg, high dosage of LP) group. In addition, carcinoma patients were randomly divided into two groups. The observation group was given LP during RT, and the control group was only treated with RT. We then compared the myelosuppression, gastrointestinal reactions, and clinical efficacy among groups. Results: In the animal experiments, compared with the control group, the number of leukocytes and lymphocytes of the mice in the "RT" group decreased (p < 0.05). Animals receiving LP evidenced a dose-response curve with regard to the number of leukocytes and lymphocytes that was proportional to the LP dose, increased (p < 0.05). Flow cytometric analyses showed that LP treatment of the mice increased the numbers of CD3+, and CD4+ T cells and theCD4+/CD8+ ratio. In our clinical study, the Radiation Therapy Oncology Group (RTOG)/European Organization for Research and Treatment of Cancer (EORTC) criteria were used for measuring myelosuppression and gastrointestinal reactions. The RTOG/EORTC grade 3 or 4 inhibition rate of leukocytes, granulocytes, hemoglobin, platelets, and gastrointestinal toxic effects in the observation group were significantly lower than that in the control group (p < 0.05). Conclusion: LP can improve the hematopoietic and immune function of RT-treated mice and reduce the hematological and gastrointestinal toxicity of patients treated with RT and improve the quality of life.

Reconsidering the efficiency of grazing exclusion using fences on the Tibetan Plateau.

Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau (TP) and elsewhere. However, there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders' livelihoods. Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP. Longer-term fencing did not bring any ecological and economic benefits. We also found that fencing hindered wildlife movement, increased grazing pressure in unfenced areas, lowered the satisfaction of herders, and rendered substantial financial costs to both regional and national governments. We recommend that traditional free grazing should be encouraged if applicable, short-term fencing (for 4-8 years) should be adopted in severely degraded grasslands, and fencing should be avoided in key wildlife habitat areas, especially the protected large mammal species.

Effects of PLK1 on proliferation, invasion and metastasis of gastric cancer cells through epithelial-mesenchymal transition.

Effects of polo-like kinase (PLK1) on proliferation, migration and invasion capacities of gastric cancer cells through epithelial-mesenchymal transition (EMT) were investigated. Small-interfering ribonucleic acid (siRNA) with targeted interference in PLK1 gene was designed and transfected into gastric cancer MGC-803 cells via Lipofectamine to inhibit the expression of PLK1 gene in MGC-803 cells. The proliferation of MGC-803 cells was detected via methyl thiazolyl tetrazolium (MTT) assay. The mRNA and protein expression of PLK1 and EMT-related marker (E-cadherin) was detected via real-time polymerase chain reaction and western blot analysis, respectively. The effects of interference in PLK1 gene on migration and invasion of MGC-803 cells were studied via wound healing assay and Transwell chamber assay, respectively. Results of MTT assay showed that compared with that in control group, the cell proliferation in PLK1 siRNA group was significantly inhibited (p<0.01). Compared with those in control group, the mRNA and protein expression of PLK1 in PLK1 siRNA group was significantly decreased (p<0.01), but the mRNA and protein expression of E-cadherin was obviously upregulated (p<0.01). Results of wound healing assay and invasion assay showed that the capacity of migration and invasion of MGC-803 cells in PLK1 siRNA group was significantly inhibited compared with those in control group (p<0.01). In conclusion, PLK1 enhances the proliferation, migration and invasion of gastric cancer MGC-803 cells through affecting EMT.

Treatment effect of conversion therapy and its correlation with VEGF expression in unresectable rectal cancer with liver metastasis.

To investigate the therapeutic effect of conversion therapy and its correlation with vascular endothelial growth factor (VEGF) expression in unresectable rectal cancer with liver metastasis. A total of 116 cases of unresectable rectal cancer patients with liver metastasis were randomly divided into control and observation group, 58 cases in each group, all of these patients were treated by conversion therapy, patients in control were treated by FOLFOXIRI treatment program, and in observation group were treated by FOLFOXIRI program treatment and bevacizumab. Efficacy and adverse reactions were compared between the two groups, the levels of VEGF in portal vein and the expression of VEGF in cancer tissue were compared, after 5 years of follow-up, the prognosis of the two groups were observed. Objective efficiency and conversion rate of observation was significantly higher than the control group, survival rate of postoperative observation was significantly higher than that of control group (P>0.05). There was no significant difference in adverse reactions between the two groups (P>0.05). The positive rate of VEGF in portal vein blood and the expression of VEGF in the observation was significantly lower than that in the control group (P<0.05). The 5-year survival rate of VEGF high expression was significantly lower than that of VEGF low expression group (P<0.05). FOLFOXIRI combined with bevacizumab in patients with unresectable hepatic metastasis of rectal cancer can provide higher conversion rate and hepatectomy opportunities, and reduce VEGF expression in patients with unresectable rectal cancer, which is closely related to VEGF expression, therefore it is beneficial to better local control and to improve long-term survival.

Identification of abnormal nuclear and mitochondrial genes in esophageal cancer cells.

The present study aimed to detect the mutation characteristics of mitochondrial DNA (mtDNA) in Eca109 of Ec9706 cells, and to investigate their association with the nuclear genome (nDNA), thus providing a basis for gene targeting therapies for esophageal squamous cell carcinoma (ESCC). In vitro­cultured Ec9706 and Eca109 cells were analyzed the changes of single­nucleotide polymorphisms (SNPs), insertions/deletions (INDELs), copy number varia-tion, and structure variation (SV) of their genome by high­throughput sequencing. The loci with SV on chromosome 1­12 of the two ESCC cell lines were ≥5% of the mtDNA, but SV on chromosome 13­22, X and Y was ≤3%; >40% of loci exhibited gain or loss; intergenic loci with INDEL changes and SNP features accounted for the majority of mutations. The affected genes encoded proteins including nDNA­encoding intra­mitochondrial­transporting proteins, ATP energy generation­associated proteins and mitochondrial electron respiratory chain proteins, and these proteins were all nucleus­encoded mitochondrial proteins. The transcription, duplication, and translation of the abnormally expressed mtDNA in Ec9706 and Eca109 cells were closely associated with disorders of nuclear DNA products.

High incidence of coding gene mutations in mitochondrial DNA in esophageal cancer.

The aim of the present study was to detect mutations in the coding genes of mitochondrial DNA (mtDNA) in three esophageal cancer cell lines and in tumor tissues obtained from 30 patients with esophageal cancer, to investigate the relationship between protein­ and RNA­coding gene mutations and esophageal cancer. mtDNA was extracted and the coding genes were sequenced and analyzed by comparing the sequencing results with the complete mitochondrial genome of Homo sapiens. The results revealed 39 mutations in the three esophageal cancer cell lines; the genes with the highest mutation frequencies included mitochondrially encoded cytochrome B (MT­CYTB), NADH dehydrogenase 5 (MT­ND5) and MT­ND4 gene. A total of 216 mutations were identified in the 30 esophageal cancer tissues, including 182 protein­coding mutations, of which MT­CYTB and MT­ND5 genes exhibited higher mutation frequencies. The results of the present study indicated that mutations in the coding genes of mtDNA in esophageal cancer cells may be related to the occurrence of esophageal cancer.