汕头海域几丁质酶产生菌的筛选及其几丁质酶编码基因研究

在汕头海域表层沉积物中分离得到69株高产几丁质酶的菌株,对其中6株形态特征差异比较明显、几丁质酶活力比较高的菌株SWCH-1、SWCH-2、SWCH-3、SWCH-5、SWCH-6和SWCH-9进行了16S rDNA序列鉴定,发现它们分别归属于5个属.即短芽孢杆菌属(Brevibacillus)、类芽孢杆菌属(Paenibacillus)、芽孢杆菌属(Bacillus)、气单胞菌属(Aeromonas)和寡养单胞菌属(Stenotrophomonas).采用兼并引物对6株菌几丁质酶编码基因的催化保守区片段进行了PCR扩增和序列分析,发现菌株均含有18家族几丁质酶编码基因;但是其编码的蛋白序列与NCBI收录的蛋白序列存在着差异,其中菌株SWCH-1和SWCH-3的蛋白序列与数据库中序列的相似性比较低,分别为85%和81%,菌株含有比较新的几丁质酶编码基因,其全基因序列的克隆和酶蛋白的纯化分析尚在进一步研究中.图6参18     

The Influence of Potassium and Phosphorus in Predisposition of Tomato to Verticillium Wilt

The effects of varying the concentration of phosphorus and potassium independently in the growing medium of pot-grown tomato plants on their subsequent susceptibility in normal medium to vascular wilt caused by Verticillium dahliae Kleb. were studied. The degree of host invasion was measured by estimating the chitin component of diseased tissue. Different levels of potassium had little effect on the degree of invasion of inoculated stems, but this was considerably enhanced in plants raised in the absence of phosphorus. Root inoculated plants were particularly resistant when raised in nutrients totally lacking in potassium, and very susceptible when raised in the absence of phosphorus.     

Representativeness and Efficiency of Bird and Insect Conservation in Norwegian Boreal Forest Reserves

I quantified local species richness of birds in different forest types and of beetles in spruce forests at different altitudes. In both cases I quantified timber production as a measure of land acquisition cost and used the ratio between the species richness and timber production as a measure of conservation cost-efficiency. I found a positive correlation between timber production and local species richness of birds as well as beetles, indicating that the forests most valuable for forestry are also the ones most valuable for biodiversity conservation. I used different selection procedures for combining sites in a reserve network to find the minimum set of sites that included all vulnerable species. The minimum set of sites for birds was 30% spruce forest, 30% pine forest, and 40% broad-leaved forest (the three main forest types). The minimum set of sites for the beetles was uniformly distributed along the altitudinal gradient. Both minimum sets were most cost-efficient for species conservation. I suggest that equal coverage of different productivity classes is more efficient for optimizing biodiversity conservation than over-representing low productivity sites. Less than 1% of Norwegian boreal forests have been protected as nature reserves. The reserve network is fairly representative with respect to altitude, but it is seriously skewed toward low productivity sites. The current network is suboptimal with respect to forest type representativeness, species protection, and cost-efficiency. This is a result of an inefficient strategy of selecting reserve sites and an unfortunate combination of selection criteria.     

昆虫抗菌肽及其基因工程研究进展

昆虫抗菌肽是一类具有免疫效应的小分子多肽,它具有热稳定、抗菌谱广、无免疫原性、作用机制独特等特性,是昆虫能够抵御自然界中许多有害微生物侵染的重要因素.近年来,随着有关抗菌肽作用机理及功能研究的深入,其在医药领域的应用越来越引起人们的关注.本文就昆虫抗菌肽的分类、生物功能、基因工程研究进展等作一综述.参33     

Insect chemical communication: Pheromones and exocrine glands of ants

Summary Chemical communication plays a very important role in the lives of many social insects. Several different types of pheromones (species-specific chemical messengers) of ants have been described, particularly those involved in recruitment, recognition, territorial and alarm behaviours. Properties of pheromones include activity in minute quantities (thus requiring sensitive methods for chemical analysis) and specificity (which can have chemotaxonomic uses). Ants produce pheromones in various exocrine glands, such as the Dufour, poison, pygidial and mandibular glands. A wide range of substances have been identified from these glands.     

The Silent Mass Extinction of Insect Herbivores in Biodiversity Hotspots

Abstract: Habitat loss is silently leading numerous insects to extinction. Conservation efforts, however, have not been designed specifically to protect these organisms, despite their ecological and evolutionary significance. On the basis of species–host area equations, parameterized with data from the literature and interviews with botanical experts, I estimated the number of specialized plant‐feeding insects (i.e., monophages) that live in 34 biodiversity hotspots and the number committed to extinction because of habitat loss. I estimated that 795,971–1,602,423 monophagous insect species live in biodiversity hotspots on 150,371 endemic plant species, which is 5.3–10.6 monophages per plant species. I calculated that 213,830–547,500 monophagous species are committed to extinction in biodiversity hotspots because of reduction of the geographic range size of their endemic hosts. I provided rankings of biodiversity hotspots on the basis of estimated richness of monophagous insects and on estimated number of extinctions of monophagous species. Extinction rates were predicted to be higher in biodiversity hotspots located along strong environmental gradients and on archipelagos, where high spatial turnover of monophagous species along the geographic distribution of their endemic plants is likely. The results strongly support the overall strategy of selecting priority conservation areas worldwide primarily on the basis of richness of endemic plants. To face the global decline of insect herbivores, one must expand the coverage of the network of protected areas and improve the richness of native plants on private lands.     

Effect of Vertebrate Grazing on Plant and Insect Community Structure

Abstract: We compared species diversity of plants and insects among grazed and ungrazed areas of Ponderosa pine–grassland communities in Arizona. Plant species richness was higher in two of three grassland communities that were grazed by native elk and deer and domestic cattle than in ungrazed areas inside a series of three large (approximately 40-ha) grazing exclosures. Similarly, plant species richness was higher in grazed areas relative to ungrazed areas at one of two series of smaller (approximately 25-m²) and short-term exclosure sites. Evenness of plant distribution, however, was greater inside ungrazed long-term exclosures but was reduced inside ungrazed short-term exclosures relative to grazed areas. Relative abundances of forbs, grasses, trees, and shrubs, and native and introduced plants did not differ between the long- and short-term grazing exclosures and their grazed counterparts. Relative abundances of some plant species changed when grazers were excluded, however. In contrast, insect species richness was not different between grazed and ungrazed habitats, although insect abundance increased 4- to 10-fold in ungrazed vegetation. Our results suggest that vertebrate grazing may increase plant richness, even in nutrient-poor, semi-arid grasslands, but may decrease insect abundances.     

深海沉积物宏基因组文库中产蛋白酶克隆的筛选及性质分析

提取东太平洋深海沉积物宏基因组DNA,构建了未培养微生物宏基因组文库.该文库平均插入片段30 kb以上,含有7 000个克隆,含外源DNA总长度约为210 Mb.从文库中筛选到18个产胞外蛋白酶的克隆,16S rRNA分析表明,它们分别来源于假单胞菌(Pseudomonas)、寡养单胞菌(Stenotrophomonas)和弧菌(Vibrio)3个菌属.根据活性大小及来源菌株的16S rRNA序列比较,选择10个蛋白酶进行酶学性质分析,结果表明,它们的最适作用pH值在7～10之间,最适作用温度在10～40℃之间.其中Pro20蛋白酶最适作用温度最低,为10℃;Pro1蛋白酶具有最适作用温度低(20℃)、pH耐受性好、热稳定性较好等特性,具有良好的应用开发潜力.图6参16     

冰川环境耐冷菌的冷适蛋白酶分离纯化及酶学性质

采用离交和凝胶层析对“中国冰川1号”耐冷菌BacilluscereusSYPA23所产的蛋白酶进行分离纯化,并进行酶学性质研究.与中温酶相比,该蛋白酶具有较高的低温催化活力,其最适催化温度为42℃,适宜pH为7.0～8.5,SDSPAGE测定的分子量(Mr)为34.2×103.金属离子Mn2 、Ca2 对该酶有激活作用,Cu2 、Hg2 、Pb2 、Co2 对其活性有一定抑制作用.该酶属金属蛋白酶,其活性受EDTA强烈抑制,不受PMSF抑制.该蛋白酶具有低温酶典型的热不稳定性,0℃下半衰期24h,但Ca2 和一些低分子醇类物质能提高其稳定性.动力学数据分析表明,该蛋白酶在低温下对底物亲和能力高,在较宽温度范围内(25～45℃)均保持着较高的催化效能.图7表3参17