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1.
丽草蛉是多种农林害虫的重要捕食性天敌昆虫,能以预蛹进行兼性滞育越冬,该属性对延长丽草蛉的产品货架期、增加产品储备量及促进产品运输具有重要意义。本研究分别测定了丽草蛉非滞育预蛹(1日龄)和滞育预蛹(1日龄、7日龄)体内的总蛋白质、脂类、糖类及醇类等主要生化物质的含量,以及脂肪酶、海藻糖酶、抗氧化酶(超氧化物歧化酶、过氧化物酶、过氧化氢酶)等关键酶的活性变化,比较了非滞育和滞育丽草蛉预蛹体内重要生化物质的差异。结果表明:滞育和非滞育丽草蛉的生理生化特征显著不同,滞育预蛹显著积累蛋白质、脂类、甘油三酯、糖原等能源物质以及甘油、海藻糖等低温保护物质,并且滞育个体的抗氧化防御能力显著增强,这些生理生化变化有助于提高丽草蛉的抗逆性,满足滞育维持期及滞育解除后恢复发育的能量需求,保证滞育个体的发育和存活。结果为解析丽草蛉滞育的生理机制奠定了基础。  相似文献   
2.
保幼激素(juvenile hormone, JH)可以调控昆虫滞育,保幼激素环氧水解酶(juvenile hormone epoxide hydrolase, JHEH)是调节保幼激素代谢的关键酶之一。为探索JHEH在七星瓢虫Coccinella septempunctata L.滞育中的调控作用,利用RT-PCR和RACE技术克隆获得七星瓢虫JHEH全长基因,命名为Csjheh(GenBank登录号:MH932586),该基因cDNA全长2 077 bp,开放阅读框(ORF)1 380 bp,编码459个氨基酸,预测蛋白质分子量为51.39 kD,理论等电点(pI)为8.79。疏水性分析结果显示该基因具有典型环氧水解酶的N末端疏水结构。氨基酸序列比对结果表明,Csjheh与中欧山松大小蠹、赤拟谷盗、丽蝇蛹集金小蜂、内华达古白蚁保幼激素环氧水解酶同源性达到64.24%。利用实时荧光定量PCR技术研究其时空表达模式,结果表明Csjheh基因在七星瓢虫成虫初羽化阶段表达量较高,滞育诱导条件下表达量呈先下降后上升的趋势,滞育60 d时与初羽化阶段接近。本研究结果对揭示JHEH参与JH的调控作用,进而调控昆虫滞育提供了理论参考。  相似文献   
3.
The objective of the study was to compare body weights and growth from birth to 18 months of age of various groups of crossbred cattle born from 1999 to 2007, being crossbreds of Ankole (A) with Brown Swiss (B), Holstein Friesian (F), Jersey (J), and Sahiwal (S). Average weights were 26.5 kg at birth, 161 kg at weaning, and 226 kg at 18 months. Both season and sex significantly affected birth weight (BW), weight at 8 and 18 months (W8 and W18), and average daily gain from weaning to 18 months (ADG18) and, unlike season, sex significantly affected average daily gain to 8 months and weaning age. The general trend was that average daily gain attained a maximum before weaning and thereafter decreased until 18 months. Least square means for AB and AF calves were comparable and significantly differed only for W18 and ADG18. AJ had the lowest BW but was comparable with AS, AJxS, and ASxJ for W8, age-adjusted weaning weight, and W18. Generally, AF was heavier than other breed groups, but the difference was smaller than expected probably because environmental conditions did not allow full expression of genetic potential for growth.  相似文献   
4.
The solid-state (13)C CP MAS NMR technique has the potential of monitoring the chemical composition in the solid state of an intact food sample. This property has been utilized to study mushrooms of different species (Pleurotus ostreatus, Pleurotus eryngii, Pleurotus pulmunarius, and Lentinula edodes), already characterized by chemical analyses for protein and dietary fiber components. Solid-state (13)C CP MAS NMR spectroscopy reveals a large difference in the ratio between the glucidic and the proteic resonances probably depending on the mushroom species. An accurate inspection by model compounds and suitable mixtures of proteins and saccharides gives a methodology to interpret these experimental data. A good correlation (R(2) = 0.93; R(2) = 0.81) has been obtained by comparing the NMR data with the results of the chemical analyses. The results suggest the possibility to perform a taxonomic study and/or a nutritional study on the basis of the ratio between protein and polysaccharide levels determined by NMR or chemical methodologies.  相似文献   
5.
Four South Carolina salt marsh impoundments and their associated tidal creeks were assessed for the culture of subtidal Crassostrea virginica. The impoundments were chosen primarily for their diversity and ranged from old large impoundments with appreciable tidal exchange and surrounded by extensive low marsh, to new small impoundments with little tidal exchange and surrounded by maritime forest. Floating and bottom hardware cloth trays (1.22 × 0.61 × 0.14 m) each holding 200 seed oysters (initial length, y = 43.8 mm) were placed at each location and sampled monthly for growth and survival. Coincidental monthly estimates of primary production (14C), phytoplankton concentrations and total organic carbon were performed. Ancillary data collected biweekly at all locations included standard hydrographic information (temperature, salinity, pH and turbidity) and nutrient determinations (nitrates, nitrites, orthophosphates and silicates).Results indicated that over a 6-month period (October–April) growth at all locations was significantly (α = 0.001) greater in ponds than in adjacent creeks and greater in floating than bottom trays. Growth means ranged from as little as 1.00 mm/month in the Wando River, to median values of approximately 2.25 mm/month in tidal creeks, to a relatively high growth rate of 3.11 mm/month in Blue Heron Pond (Kiawah Island). Survival was high in all areas ranging from 85.0% at Blue Heron Pond to 94.5% at Kiawah Creek. There was no significant difference in survival in comparisons among locations. A direct correlation of growth in oysters, primary production and phytoplankton biomass was established. This relationship was reiterated by indications of an inverse correlation between nutrient concentrations and growth.  相似文献   
6.
The aims of the present study were to relate intramammary infection (IMI) occurrence and somatic cell count (SCC) with teat-end condition (TEC) and udder cleanliness (UC). Milk samples from 1931 teats were evaluated according to the presence of IMI and SCC. Scores were applied to teats according to the TEC and to UC. Teats ends with a very rough ring had the largest number of IMI when compared to the other three categories, as well as animals with dirtier udders. The change in a TEC score increased by around 30% the chance of IMI. Also, the chance of the animal developing IMI increased by approximately 47% when the UC score increased. No significant association between both scores and quarter SCC was found. It can be concluded that animals with very rough teat end rings and very dirty udders have a greater predisposition to IMI.  相似文献   
7.
草蛉是多种农林害虫的重要捕食性天敌昆虫,在生物防治中具有重要作用。滞育是昆虫应对不利环境条件时,生长发育停滞的一种生理状态,许多草蛉种类存在滞育现象。深入开展草蛉滞育的研究,不仅有助于明确其滞育特征和内在调控机制,也有助于提高草蛉的生物防治效果,促进草蛉的商业化生产和应用。本文归纳总结了1910年以来国内外草蛉科种类的滞育研究文献,介绍了目前已开展滞育研究的草蛉种类及其滞育特征,分析了影响草蛉滞育调控的环境因子,论述了草蛉滞育期间的形态和生理生化变化、分子机制及其滞育后发育生物学,并就滞育在草蛉规模化生产中的应用以及目前草蛉滞育研究中存在的问题进行了讨论,以期为深入草蛉滞育的基础理论研究和促进草蛉的规模化生产应用等提供参考依据。  相似文献   
8.
During 1976, epibionts were noted on adult Malaysian prawns reared in a special ‘brood stock pond’. These epibionts have not previously been recorded on Macrobrachium rosenbergii. Dense algal growths, covering much of the carapace, were observed on 58.3% of the males (mean size, 147.1 g) and on none of the females at harvest. Species composition was primarily (about 90%) the Chlorophyte Oedogonium crassiusculum, with the Cyanophyte Lyngbya, the secondary dominant. The large infested males were sluggish and in some cases functionally blind due to the algal covering. However, once moved to indoor culture tanks the algae were lost and the prawns' behavior returned to normal.Eggs of the water boatman, Ramphocorixa acuminata, were observed on 52.5% of the females (mean size, 78.0 g) and 5.9% of the males at harvest. Egg deposition was limited to the cephalothorax and/or the first and/or second abdominal segments. This epibiont was not noted in the six adjacent rearing ponds containing approximately 84,000 smaller prawns. The insect eggs appeared to cause no injury and disappeared shortly after the infested prawns were returned to laboratory tanks.Although both epibionts exhibited apparent sex specificity in the brood stock pond, data from other rearing ponds did not support this specificity. The occurrence of these epibionts should pose no problem to the successful pond culture of M. rosenbergii in South Carolina.  相似文献   
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