小麦叶蜂危害的产量损失与防治指标研究

当小麦叶蜂幼虫数量相等时,在较干旱的年份（1988）危害较重;而在气候较湿润的年份（1989）危害较轻。虫量与产量损失成正相关（r=0．9821**）,其中以25头／m2幼虫危害的产量损失突增,达显著水平,可以认定为防治指标。     

增温对高寒草甸群落凋落物质量动态变化的影响

为了解未来增温条件下,青藏高原高寒草甸凋落物质量如何变化,将有助于增强对高寒草甸生态系统碳源/汇效应的认识.该文通过定位可控的增温试验平台,动态监测了凋落物生物量及其质量的变化.结果表明:增温显著地促进了凋落物的分解速率(F=35.757,P＜0.001),降低了凋落物中的C、N含量及其C/N比,但提高了凋落物中的P含...     

光呼吸和谷氨酰胺合成酶抑制剂对水稻冠层NH3挥发的影响

在营养液培养条件下,对两个不同氮效率基因型水稻品种扬稻6号和武育粳3号采用光呼吸抑制剂异烟肼（INH）和谷氨酰胺合成酶（GS）抑制剂蛋氨酸亚砜亚胺（MSO）处理,研究其对水稻光合速率、光呼吸速率、GS酶活性及冠层的NH。挥发速率的影响。结果发现：（1）MSO导致剑叶光合速率下降,光呼吸速率升高;INH导致光呼吸速率显著下降,同时一定程度上引起光合速率降低。（2）MSO处理显著降低了GS酶活性,相应地引起NH。挥发速率增加;INH在一定程度上导致NH。挥发速率降低。（3）扬稻6号NH。挥发速率比武育粳3号低的生理原因是光呼吸速率较低和GS酶活性较高。     

Stabilization of cold-adapted protease MCP-01 promoted by trehalose: prevention of the autolysis

Protease MCP-01 is similar to other cold-adapted enzymes in that it is a cold-adapted serine protease having high specific activity and low thermostability at low and moderate temperature. Its thermolability and self-autolysis has resulted in difficulties in its purification, preservation and research on its structure and function. The disaccharide trehalose is known to effectively stabilize proteins. Its prevention effect on the autolysis of cold-adapted protease MCP-01 was monitored by capillary electrophoresis. In the absence of trehalose, protease MCP-01 autolyzed rapidly at 35 degrees C. However, when trehalose was added, autolysis was remarkably prevented and the loss of activity reduced. MCP-01 may be a useful model for basic research on the interaction of protein and trehalose.     

Identification of a four-gene metabolic signature predicting overall survival for hepatocellular carcinoma

While hundreds of consistently altered metabolic genes had been identified in hepatocellular carcinoma (HCC), the prognostic role of them remains to be further elucidated. Messenger RNA expression profiles and clinicopathological data were downloaded from The Cancer Genome Atlas—Liver Hepatocellular Carcinoma and GSE14520 data set from the Gene Expression Omnibus database. Univariate Cox regression analysis and lasso Cox regression model established a novel four-gene metabolic signature (including acetyl-CoA acetyltransferase 1, glutamic-oxaloacetic transaminase 2, phosphatidylserine synthase 2, and uridine-cytidine kinase 2) for HCC prognosis prediction. Patients in the high-risk group shown significantly poorer survival than patients in the low-risk group. The signature was significantly correlated with other negative prognostic factors such as higher α-fetoprotein. The signature was found to be an independent prognostic factor for HCC survival. Nomogram including the signature shown some clinical net benefit for overall survival prediction. Furthermore, gene set enrichment analyses revealed several significantly enriched pathways, which might help explain the underlying mechanisms. Our study identified a novel robust four-gene metabolic signature for HCC prognosis prediction. The signature might reflect the dysregulated metabolic microenvironment and provided potential biomarkers for metabolic therapy and treatment response prediction in HCC.     

Analysis of novel angiotensin-I-converting enzyme inhibitory peptides from protease-hydrolyzed marine shrimp Acetes chinensis.

Acetes chinensis is an underutilized shrimp species thriving in the Bo Hai Gulf of China. In a previous study, we had used the protease from Bacillus sp. SM98011 to digest this kind of shrimp and found that the oligopeptide-enriched hydrolysate possessed antioxidant activity and high angiotensin I-converting enzyme (ACE) inhibitory activity with an IC50 value of 0.97 mg/ml. In this paper, by ultrafiltration, gel permeation chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC), five peptides with high ACE inhibitory activity were purified from the shrimp hydrolysates and their sequences were identified by amino acid composition analysis and molecular weight (MW) analysis. Three of them, FCVLRP (a), IFVPAF (f) and KPPETV (j), were novel ACE inhibitory peptides. Their IC50 values were 12.3 microM, 3.4 microM and 24.1 microM, respectively, and their recoveries were 30 mg/100 g (solid basis of shrimp), 19 mg/100 g and 33 mg/100 g, respectively. Lineweaver-Burk plots for the three novel peptides showed that they are all competitive inhibitors. To test the ACE inhibitory activity of peptide a, f, j after they were digested by digestive enzymes in vivo, 12 derived peptides from FCVLRP and IFVPAF were synthesized based on their amino acid sequences and the cleavage sites of digestive enzymes. No digestive enzyme cleavage site was found in KPPETV. The IC50 values of the derived peptides were determined and the result showed that except for VPAF, FC and FCVL, the ACE inhibitory activity of the other nine derived peptides did not significantly change when compared with their original peptides. Surprisingly, five peptides had lower IC50 values than their original peptides, particularly for RP (IC50 value = 0.39 microM), which is about 30 times lower than its original peptide and almost the lowest IC50 value for ACE inhibitory peptides reported. Therefore, the novel peptides identified from A. chinensis hydrolysates probably still maintain a high ACE inhibitory activity even if they are digested in vivo. This is the first report about novel ACE inhibitory peptides from hydrolysates of marine shrimp A. chinensis. The novel peptides from hydrolysate of A. chinensis and some of their derived peptides with high ACE inhibitory activity probably have potential in the treatment of hypertension or in clinical nutrition.     

Phylogeography of <Emphasis Type="Italic">Achyranthes bidentata</Emphasis> (Amaranthaceae) in China’s Warm-Temperate Zone Inferred from Chloroplast and Nuclear DNA: Insights into Population Dynamics in Response to Climate Change During the Pleistocene

Previous phylogeographic studies of the warm-temperate zone in China focused on woody plants, but little attention was given to the climate-sensitive herbaceous plants. In this work, we implemented a phylogeographic survey on the perennial herb Achyranthes bidentata in China’s warm-temperate zone. The sequence variation of cpDNA and nDNA was examined across 209 individuals from 21 populations. A total of 11 chlorotypes and 26 ribotypes were identified. The cpDNA data showed weak population genetic differentiation and could not divide the 21 populations into different genetic groups. By contrast, the nDNA data revealed stronger genetic differentiation than cpDNA and could divide these populations into two genetic groups. The cpDNA and nDNA data both gave unambiguous signs of recent sudden population expansion. Based on the cpDNA and nDNA data, the estimated time of population expansion occurred at interglacial Marine Isotope Stage (MIS) 9 of the Penultimate Glaciation in China. The cpDNA and nDNA data suggested that the glaciation during this period deeply influenced the current distribution patterns and intraspecific divergence of A. bidentata. Our survey showed that A. bidentata tracked climatic oscillations by a large range of southward retreat into three main refugia during MIS 8, followed by the sudden northward expansion from these refugia during MIS 9.