目标昆虫对Bt杀虫晶体蛋白抗性的研究概况

综述了多种目标昆虫对Bt杀虫晶体蛋白的抗性机制和遗传特性。     

Effects of dietary pyridoxine on growth and biochemical responses of Labeo rohita fingerlings exposed to endosulfan

A sixty-day experiment was carried out to study the effect of dietary pyridoxine (PN) on growth performance, RNA/DNA ratio and some biochemical parameters of Labeo rohita fingerlings exposed to sub-lethal dose of endosulfan (1/10th of 96 h static non-renewal LC₅₀ = 0.2 ppb) to assess the role of pyridoxine in ameliorating the negative effects of endosulfan. Two hundred seventy fingerlings (6.5 ± 0.26 g) were randomly distributed into six treatments in triplicates (15 fish/tank). Five iso-nitrogenous (35.45-35.75% crude protein) purified diets were prepared with graded levels of pyridoxine. Six treatment groups were T₀ (10 mg PN + without endosulfan), T₁ (0 mg PN + endosulfan), T₂ (10 mg PN + endosulfan), T₃ (50 mg PN + endosulfan), T₄ (100 mg PN + endosulfan) and T₅ (200 mg PN + endosulfan). Weight gain (%), specific growth rate (SGR), tissue glycogen, and protease activity were significantly (P < 0.05) higher in pyridoxine fed groups compared to their non-pyridoxine fed counterpart. Protease activity was positively correlated (R² = 0.931) with (%) weight gain. Glucose-6-phosphate dehydrogenase (G6PDH) activity was significantly (P < 0.05) higher in non-pyridoxine fed group and decreased in pyridoxine fed counterparts. There were no significant (P > 0.05) effect of dietary pyridoxine on feed conversion ratio (FCR), protein efficiency ratio (PER), survival, gastro-somatic index (GSI), hepato-somatic index (HSI) and liver and muscle DNA levels of L. rohita fingerlings. RNA levels, both in liver and muscle, increased significantly (P < 0.05) in pyridoxine fed groups. A positive correlation was observed between growth and RNA levels, both in liver (R² = 0.91) and muscle (R² = 0.88). RNA/DNA ratio showed a third order polynomial relationship with dietary pyridoxine, both in liver (Y = −0.014x³ + 0.1613x² − 0.5333x + 0.7933, R² = 0.987) and muscle (Y = −0.0407x³ + 0.4763x² − 1.6358x + 2.4667, R² = 0.9345). The overall results obtained in present study indicated that dietary pyridoxine supplementation at 100 or 200 mg PN/kg diet ameliorates the negative effects of endosulfan and restores optimal growth of L. rohita fingerlings.     

1株产蛋白酶菌株的分离鉴定及其产酶条件的优化

为得到具有实际应用价值的高效产蛋白酶菌株,以甘肃省夏河地区深度20～30 m处的土样为基质,以菌株生长出的透明水解圈直径大小与菌落大小之比为基础,进行菌株产蛋白酶的活力测定,从而筛选得到优良菌株.结果表明,自甘肃夏河土壤中分离得到的编号为NWMCC0320的菌株产酶活力最高,为114.21U/mL;经多种有效的菌株鉴定...     

Rhododendron thickets alter N cycling and soil extracellular enzyme activities in southern Appalachian hardwood forests

Rhododendron maximum L., a spreading understory shrub, inhibits overstory regeneration and alters forest community structure in southern Appalachian hardwood forests. Using paired plots and reciprocal litter transplants in forests with and without R. maximum cover, we examined the influence of R. maximum on litter mass and quality, N cycling and soil extracellular enzymes. Standing stocks of soil organic matter, soil N, leaf litter mass and fine root biomass were greater in forests with R. maximum than those without. Tannin extracts from R. maximum foliage, and leaf litter and fine roots collected under R. maximum had a relatively high capacity to precipitate protein compared to extracts from trees. Across the growing season, soil inorganic N availability was generally lower under R. maximum, mostly due to reduced NO₃⁻ availability. Our data suggest that R. maximum litter alters N cycling through the formation of recalcitrant polyphenol–organic N complexes. Soil extracellular enzymes indicate the potential processing rates of organic substrates. Between forest types, polyphenol oxidase activity was greatest in R. maximum O horizons, regardless of litter type, suggesting that the local microbial community can better degrade and access protein–tannin-complexed N. Protease activity did not differ between forest types, but was greater on R. maximum leaf litter than hardwood leaf litter. The alteration of the N cycle via the formation of polyphenol–organic N complexes may contribute to hardwood seedling suppression, while the enzymatic release of these complexes by ericoid mycorrhizal fungi may increase N acquisition for R. maximum and contribute to its expansion in southern Appalachian forests.     

Effect of the addition of municipal solid-waste compost on microbial biomass and enzyme activities in soil

Summary Changes in the content of C, N, P, and S in the soil biomass and in phosphatase, urease, protease, deaminase, and arylsulphatase activity, induced by amendment with municipal solid-waste compost, were determined in a clay loam soil during 1 year of incubation at 25° and 35°C.In the unenriched soil (control) decreasing trends in biomass C, biomass N, and biomass S were observed at both temperatures. In the enriched soil, these values increased, reaching a maximum after 1 month. Biomass P, probably due to a slower process of P immobilization, showed different trends. Alkaline phosphomonoesterase, phosphodiesterase, and deaminase activity remained constant after reaching maximum values (3–5 months). Arylsulphatase, urease, and protease activity tended to return to baseline after reaching a maximum (2–3 months).Atrazine, though applied at a dose that was 10 times higher than the recommended field rate, did not modify the chemical and biochemical properties of either the control or the enriched soil.Significant positive and negative correlations between changes in biomass values and changes in enzyme activity were found. The negative correlations are attributed to the delay in the enzymatic response compared with the changes in microbial biomass.     

Drought decreases soil enzyme activity in a Mediterranean Quercus ilex L. forest

Longer and more severe drought periods are expected in the near future for Mediterranean ecosystems. Soil enzymes play an essential role in the nutrient mineralization and their activity is an exceptional sensor in predicting the capacity of nutrient supply to plants. We conducted an experiment of water availability manipulation in evergreen oak mountain stands with the aim to study the effects of enhanced drought on the activity of five soil enzymes. The drought treatment consisted of runoff exclusion by a ditch along the entire top edge of the upper part of treatment plots and partial rain exclusion by suspending PVC strips and funnels. The reduction of 10% of soil moisture produced by runoff exclusion decreased urease activity by 10-67%, protease activity by 15-66% and β-glucosidase activity by 10-80%, depending on annual period and soil depth. The reduction of 21% of soil moisture produced by runoff and rainfall exclusion together reduced urease activity by 42-60%, protease activity by 35-45%, β-glucosidase activity by 35-83% and acid phosphatase activity by 31-40%. No significant effects were observed on alkaline phosphatase activity. The activities of the enzymes involved in the nitrogen cycle, protease and urease, were the most affected by drought. In all cases, the activities of these enzymes strongly decreased with soil depth and they were greater in spring than in autumn. These results show the link between drought and a slower nutrient turn-over, which decreases the nutrient supply to plants.     

干旱和半干旱地区不同营养条件下小麦衰老期相关生理生化指标变化动态

采用析因分析的方法,研究了干旱半干旱地区不同栽培模式条件下,小麦旗叶衰老后期相关生理生化反应指标的动态变化.结果表明,自花后15 d开始,小麦衰老可以分为两个阶段:平缓期和加速降解期.平缓期:叶绿素含量、可溶性蛋白质,蛋白水解酶以及POD、SOD活性总体呈下降趋势,但下降速率比较平缓.加速降解期:叶绿素含量、SOD活性和可溶性蛋白质含量均有大幅度的下降;而与之相对应的是:蛋白水解酶、POD活性迅速升高.叶绿素含量的析因分析表明:花后15～19 d氮肥对叶绿素含量贡献较大,而花后19～32 d水分对叶绿素含量效应显著,在此基础上,对不同的栽培模式比较认为,高氮比低氮效果好,水分效果较好的为FM模式,最适栽培模式为FM8.     

A Study on the Inhibitory Potency of Protease Inhibitors in Porcine Colostrum

Porcine colostrum and milk were separated into the acid-soluble fraction (SF) and casein frac-tion (CF) by centrifuge. Trypsin and chymotrypsin inhibitory capacity in porcine colostrum, milk and theircomponents were determined by incubating bovine trypsin or chymotrypsin in a medium. The inhibition of in-sulin-like growth factor Ⅰ (IGF-Ⅰ) and epidermal growth factor (EGF) degradation in pig small intestinal con-tents by porcine colostrum was measured by incubating iodinated IGF-Ⅰ or EGF. Degradation of labeled IGF-Ⅰor EGF was determined by monitoring the generation of radioactivity soluble in 30% trichloroacetic acid(TCA). The results showed that porcine colostrum had high levels of trypsin and chymotrypsin inhibitory ac-tivity and increased the stability of IGF-Ⅰ and EGF in pig intestinal contents. The SF was higher in inhibitorypotency than CF. The present study revealed that the protease inhibitors in porcine colostrum, milk-derivedand colostrum-specific, existed mainly in SF.     

一株蛋白酶产生菌分离及鉴定

蛋白酶在饲料加工行业中有广泛应用。为了获得高产蛋白酶菌株,本实验采用透明圈法进行初筛,通过Folin-酚法进行复筛,从土壤中获得了一株产蛋白酶能力较高的菌株S-3。通过生理生化反应和16S rDNA基因分析,鉴定其为贝莱斯芽孢杆菌（Bacillus velezensis）。本实验为贝莱斯芽孢杆菌应用于蛋白酶生产提供了理论依据。     

几种芽孢杆菌共培养对产蛋白酶的影响

[目的]为了研究芽孢杆菌的共发酵对蛋白酶产量的影响。[方法]对4株具有产蛋白酶能力的芽孢杆菌,通过菌株两两配伍发酵或三者配伍共发酵培养,分别检测单一菌株发酵产物和不同菌株共发酵产物的蛋白酶活性。[结果]枯草芽孢杆菌、纳豆芽孢杆菌、地衣芽孢杆菌、蜡样芽孢杆菌均具有一定的产蛋白酶能力,枯草芽孢杆菌、纳豆芽孢杆菌共发酵培养48 h后蛋白酶活力有显著提高。[结论]菌株之间的科学配伍在共发酵中可以显著提高蛋白酶的活性。