Effects of soluble tea polysaccharides on hyperglycemia in alloxan-diabetic mice

The effects of tea water extracts (TWE), crude tea polysaccharides (CTP), and a tea polysaccharide fraction (TPF) were tested on hyperglycemic diabetic mice. Results indicated that TWE, CTP, and TPF could significantly decrease fasting blood glucose (FBG) and glucosylated serum protein (GSP) in alloxan-induced diabetic mice compared to the control group. In vitro antioxidant activities of TWE, CTP, and TPF for scavenging hydroxyl radicals and superoxide radicals decreased with the degree of purification and were lowest for TPF. High-performance gel permeation chromatography (HPGPC) and component analysis revealed the molecular mass distribution and constituents of TWE, CTP, and TPF, indicating that a 100-120 kDa fraction contained the hypoglycemic activity. This fraction was essentially composed of polysaccharides (approximately 90%) with substantial amounts of arabinogalactan proteins. The second-derivative IR spectra of TWE, CTP, and TPF with peak intensity around 1075 and 1045 cm(-1), which characterize galactopyranose in the backbone and arabinofuranose units in side branches, respectively, further substantiated the importance of the arabinogalactan proteins. Taken together, the results indicate that a soluble tea polysaccharide is the major hypoglycemic factor in tea and that this polysaccharide may be developed to a potential natural hypoglycemic functional ingredient.     

Protein engineering of Sulfolobus solfataricus maltooligosyltrehalose synthase to alter its selectivity

Maltooligosyltrehalose synthase (MTSase) is one of the key enzymes involved in trehalose production from starch and catalyzes an intramolecular transglycosylation reaction by converting the alpha-1,4- to alpha,alpha-1,1-glucosidic linkage. Mutations at residues F206, F207, and F405 were constructed to change the selectivity of the enzyme because the changes in selectivity could reduce the side hydrolysis reaction of releasing glucose and thus increase trehalose production from starch. As compared with wild-type MTSase, F405Y and F405M MTSases had decreased ratios of the initial rate of glucose formation to that of trehalose formation in starch digestion at 75 degrees C when wild-type and mutant MTSases were, respectively, used with isoamylase and maltooligosyltrehalose trehalohydrolase (MTHase). The highest trehalose yield from starch digestion was by the mutant MTSase having the lowest initial rate of glucose formation to trehalose formation, and this predicted high trehalose yield better than the ratio of catalytic efficiency for hydrolysis to that for transglycosylation.     

Lead optimization and insecticidal activity of analogues of daphneolone isolated from Stellera chamaejasme L

Starting from the chemical structure of the botanical aphicides 1,5-diphenyl-1-pentanone and 1,5-diphenyl-2-penten-1-one, extracted from Stellera chamaejasme L., the authors designed and synthesized a series of novel compounds following the concept of bioisosterism. Their structures were established on the basis of (1)H NMR and GC-MS spectra, and the insecticidal activities of the compounds were evaluated against Aphis gossypii Glover. The results demonstrated that the substitution of a heterocycle for the phenyl ring was favourable. Thus, further modification of compound 2n, containing a furan ring, which showed excellent activity (LC(50) = 0.85 g L(-1)), is of some promise.     

Hypovirulence and Double-Stranded RNA in Botrytis cinerea

ABSTRACT Twenty-one strains of Botrytis cinerea isolated from 13 species of plants grown in China were compared for pathogenicity on Brassica napus, mycelial growth on potato dextrose agar, and presence of double-stranded (ds)RNA. The results showed that the strain CanBc-1 was severely debilitated in pathogenicity and mycelial growth, compared with the 20 virulent strains. A dsRNA of approximately 3.0 kb in length was detected in CanBc-1 and 4 hypovirulent single-conidium (SC) isolates of CanBc-1, but was not detected in the 20 virulent strains of B. cinerea and 4 virulent SC isolates of CanBc-1. Results of the horizontal transmission experiment showed that the hypovirulent trait of CanBc-1 was transmissible and the 3.0-kb dsRNA was involved in the transmission of hypovirulence. Analysis of a 920-bp cDNA sequence generated from the 3.0-kb dsRNA of CanBc-1 indicated that the dsRNA element was a mycovirus, designated as B. cinerea debilitation-related virus (BcDRV). Further analyses showed that BcDRV is closely related to Ophiostoma mitovirus 3b infecting O. novo-ulmi, the causal agent of Dutch elm disease. Mitochondria and cytoplasm in hyphal cells of CanBc-1 became degenerated, compared with the virulent isolate CanBc-1c-66 of B cinerea. This is the first report on the occurrence of Mitovirus-associated hypovirulence in B. cinerea.     

挠力河自然保护区不同作物类型退耕还湿地浮游植物群落结构特征

为了解挠力河自然保护区内不同作物类型退耕还湿地浮游植物群落结构的差异,于2020年7月选取了大豆、玉米、水稻3种作物类型的退耕还湿地共8个样点进行浮游植物调查,并分析浮游植物同环境因子的关系。结果表明：研究样地共鉴定出浮游植物137种,其中绿藻门种类最多(40.15%),其次为硅藻门(22.63%)、裸藻门(16.06%)、蓝藻门(13.14%)。3种作物类型的退耕还湿地之间浮游植物群落结构(种类数、丰度、生物量、多样性指数)差异不显著。水质指标、浮游植物优势种及丰度说明退耕湿地水质处于重度污染状态和富营养化状态。RDA分析显示,退耕湿地浮游植物主要受化学需氧量的影响。     

我国省级湿地保护法规完备程度及严格程度评估

文中首先基于条例总体、管理体制机制、湿地保护管理、湿地利用管理、湿地修复与生态补偿5个方面共72项指标构建完备程度指数,进一步结合22项严格程度附加指标建立严格程度指数,据此对我国已出台的省级湿地保护法规文本进行评估。结果表明:1)27部省级法规的完备程度指数和严格程度指数均值分别为0.645和0.614,完备程度指数居前3位的分别为江苏、宁夏、北京,严格程度指数前3位分别为江苏、黑龙江、宁夏;2)在单项指标方面,被各省级法规覆盖程度低于1/3的指标主要包括湿地保护目标责任制、上级政府对下级政府的监督、专家咨询与专家委员会、湿地利用一般性规定的违法法律责任、湿地占用分级规定、占补平衡相关指标、项目环境影响评价、受保护的野生动植物的保护管理、湿地修复技术要求、湿地修复责任主体区分等,这些是进一步完善省级湿地保护法规时需重点补充的内容。研究结果可为各省进一步完善湿地保护法规、健全湿地保护制度体系提供参考。     

几种鲶鱼的养殖技术之六杂交鲶细菌性出血病的诊断及防治

２００１年，四川省阆中市水产局从四川省水产研究所引进了杂交鲶，该鱼生长速度快，抗病力强，饵料系数低。但在养殖的过程中，由于环境的恶化，易患细菌性出血病，现将杂交鲶细菌性出血病的诊断防治方法介绍如下，供养殖户参考。杂交鲶细菌性出血病的主要症状表现为：病鱼最初表现为独游水面，头上尾下，嘴张开，稍惊即窜游于水下，不久又上游；鳍基部有轻度充血现象；临近死亡时，病鱼激烈翻滚、窜游。病鱼头顶部明显充血、出血，眼球突出，眼眶出血，鳍及鳍基出血，鳍条末端稍腐烂，体表充血发炎，鳃丝颜色变淡，粘液增多，其末端出现不…     

Choline requirements of male White Pekin ducks from 21 to 42 d of age

1. A dose–response experiment with 6 dietary choline concentrations (0, 342, 779, 1285, 1662 and 1962 mg/kg) was conducted with male White Pekin ducks to estimate the choline requirement from 21 to 42 d of age.

2. Ninety 21-d-old male White Pekin ducks were allotted to 6 dietary treatments, each containing 5 replicate pens with three birds per pen. At 42 d of age, final weight, weight gain, feed intake and feed/gain were measured. Liver was collected to determine total liver lipid, triglyceride and phospholipids.

3. Significant positive effects of dietary choline on final weight, weight gain and feed intake were observed. In addition, dietary choline supplementation significantly decreased liver lipid and triglyceride content and increased liver phospholipids of Pekin ducks.

4. According to broken-line regression analysis, the choline requirements of male White Pekin ducks from 21 to 42 d of age for weight gain, feed intake and total liver lipid were 980, 950 and 1130 mg/kg. Pekin ducks needed more choline to prevent excess liver lipid deposition than to maintain growth.     

Seroprevalence and molecular detection of Mycoplasma ovipneumoniae in goats in tropical China

In the present study, the seroprevalence and genetic identification of Mycoplasma ovipneumoniae infection in goats were investigated in Hainan Province, tropical China between October 2012 and October 2013. A total of 1,210 serum samples collected from 16 herds in various administrative regions in tropical China were evaluated using indirect hemagglutination assay (IHA). Antibodies to M. ovipneumoniae were tested in (31.7 %, 95 % confidence interval (CI) 29–34.3) 383 of 1,210 serum samples (IHA titer ≥1:16). The M. ovipneumoniae seroprevalence ranged from 26.8 % (95 % CI 20.8–32.9) to 39 % (95 % CI 30.8–47.2) among different regions in tropical China, and the difference was statistically significant (P?<?0.01). The seroprevalence of M. ovipneumoniae infection in goats was higher in winter (46.1 %, 95 % CI 39.6–52.5) and spring (33.8 %, 95 % CI 28.3–39.3) than in autumn (27.5 %, 95 % CI 22.6–32.3) and summer (24.7 %, 95 % CI 20.3–29.1), and the difference was statistically significant (P?<?0.01). In addition, DNA was extracted from nasal swab; lung samples and the 16S rRNA gene sequences were amplified by polymerase chain reaction (PCR) and then sequenced. Twenty-four of 329 (7.3 %) nasal swab samples and 73 of 280 (26.1 %) pneumonic lung tissues were found to contain M. ovipneumoniae, respectively. The results of the present survey indicate that M. ovipneumoniae infection is highly prevalent in goats in tropical China. This is the first report of the comprehensive survey of M. ovipneumoniae prevalence in goats in China.