草鱼肠炎病病原研究的进展

草鱼肠炎病是草鱼中流行广、危害大的一种鱼病。自1953年以来,为了有效地控制此病,对防治方法及其病原进行了研究。1958年从病鱼中分离到一种肠型点状产气杆菌(Aeromonas punctata f.intestinalis),通过对健康鱼腹腔注射感染,获得了阳性结果,因而被定为草鱼肠炎的致病菌。       

铜锈环稜螺繁殖和生长的初步研究

作者于1963年3月至1964年6月间对武昌东湖的铜锈环稜螺的某些生态学问题进行了初步研究:自然种群中铜锈环稜螺的性比为1∶1。成熟雌螺全年怀胚,月平均怀胚数以5月初最高,7、8、9月最低,生活于池塘中的雌螺的怀胚数又高于湖泊中相应壳高组雌螺的怀胚数。生殖季节自4月中旬至11月底,其中以6月份产螺达高峰,其临界水温为16—18℃,最适水温在26℃左右。雌螺生长至壳高15—16毫米开始生殖。在自然种群中,每一雌螺每年平均产螺49.7个。雌螺所产仔螺的大小与年龄有关。对铜锈环稜螺的生长规律,提出了有关方程式。       

青鱼性腺发育的研究

湖南地区生长于池塘环境的青鱼,性成熟年龄是5—6年,雄性比雌性普遍地早熟一年。卵母细胞和滤泡细胞是同源的,都来自于卵原细胞。池养青鱼的卵母细胞只能发育到初级卵母细胞阶段(Ⅳ时相),必须通过人工催情,才能进行染色体的减数分裂,使卵母细胞由第Ⅳ时相发育到第Ⅴ时相。精细胞的发生,能够完成由精原细胞到精子的全部发育过程。青鱼在第一次性周期内,雄性精巢在第5个冬季进入第Ⅳ期,雌性卵巢在第6个冬季进入第Ⅲ期,从此以后,每年冬季,雄性精巢回复到第Ⅳ期,雌性卵巢回复到第Ⅲ期,这种性腺季节周期变化的规律,为生产上选留亲鱼提供了理论依据。青鱼雌性卵母细胞由第Ⅲ时相到第Ⅳ时相是同步性的;经人工催情产卵或自然退化后,卵巢的组织学结构又回复到第Ⅱ期,证明青鱼是一次产卵类型。已经达到性成熟年龄的雌性青鱼,卵母细胞的卵黄形成有两种不同的类型。第一种类型是泡内卵黄,第二种类型是泡外卵黄。如果饲养管理工作如投饵、水质调节不适宜,卵母细胞不能正常形成卵黄,就会出现卵子的败育现象,这是生产上一个重要问题,必须进一步研究。       

UN system efforts to support the response to AIDS in China

INTRODUCTION China has made considerable progress in the response to the AIDS epidemic in the past years, particularly in terms of commitment by the national leadership, the establish- ment of a supportive policy framework, improved under- standing of the…     

Modeling the Circulation of a Disease Between Two Host Populations on non Coincident Spatial Domains

We derive a reaction–diffusion system modeling the spatial propagation of a disease with kinetics occurring on distinct spatial domains. This corresponds to the actual invasion of a disease from a species living in a given spatial domain toward a second species living in a different spatial domain. We study the global existence of solutions and discuss the long time behavior of solutions. Then we consider a special case, based on a model of brain worm infection from white-tailed deer to moose populations, for which we discuss the invasion success/failure process and disprove a conjecture stated in an earlier work.     

Phytoecdysones from Parana discifera

From the aerial parts of Parana discifera, 10 phytoecdysones, β- ecdysterone (1) and its 2 -acetate (2) , 3 - acetate (3), 25 - acetate (4) ,2,3- acetonide (5) , 20, 22 - acetonide (6) , and 2 -deoxyecdysterone (7) and its 20, 22 - acetonide (8), 3-O-β-D- glucopyranoside (9) and posterone (10) were isolated. They have no anti - inflammatory, analgesic, sedative, anti - convulsant and anti -cerebra- hypoxic activities in animal testing with Kunming mice.     

Plant responses to ultraviolet-B (UV-B: 280–320 nm) stress: What are the key regulators?

Depletion of the stratospheric ozone layer is leadingto an increase in ultraviolet-B (UV-B: 280–320 nm)radiation reaching the earth's surface. This hasraised interest in the possible consequence ofincreased UV-B levels on plant growth and developmentand the mechanisms underlying these responses. Although the effects of UV-B are now wellcharacterised at the physiological level, little isknown about the cellular and molecular mechanismsinvolved. Recent studies have shown that UV-B affectsa number of important physiological processes, such asphotosynthesis, through effects on gene expression. In addition, induction of a number of defensemechanisms, such as production of UV-B screeningpigments, increase in antioxidant enzymes andinduction of pathogenesis-related proteins, are alsomediated at the level of gene expression. The signaltransduction pathways by which UV-B regulates geneexpression are at present poorly understood. Thestudies carried out to date have, however, indicateda pivotal role for reactive oxygen species as keysecond messengers acting up-stream of a number ofpathways involving the plant hormones salicylic acid,jasmonic acid and ethylene. The transduction pathwaysidentified to date and the role of intermediates inregulating tolerance to UV-B damage are discussed inthis review.     

对金龟子具有杀虫专一性的苏云金芽孢杆菌综述(英文)

自从 190 1年Ishiwata首次报导猝倒菌以来 ,已有数千篇有关苏云金芽孢杆菌的论文相继发表。在苏云金芽孢杆菌 (Bt)的害虫生物防治领域中首次发现对鳞翅目昆虫有杀虫专一性的Bt菌株以后 ,又有了划时代的进展。Goldberg和Margalit发现了杀双翅目幼虫的以色列亚种 (subsp .isrealensis) ,以及Kreig等人发现了对某些鞘翅目幼虫有毒的拟步行甲亚种 (sbusp .tenebrionis)。 1992年 ,Ohba等分离到了日本亚种(subsp .japonensis)对金龟子有专一性杀虫作用的菌株Buibui。该菌株及与之有关的研究进展即是本文讨论的重点。这些发现不仅丰富了苏云金芽孢杆菌科学 ,也丰富了生物防治的应用策略。另一方面 ,在毒素蛋白结构及其杀虫机制的分子生物学和生物化学领域也已获巨大进展。但对杀虫机制尚未完全明了。例如 ,对杀虫蛋白与中肠上皮细胞原生质膜上的受体蛋白的相互作用就知之甚少。这一领域在某种程度上还是众说纷纭。展论这些令人兴奋而又难解的课题将最终促成二十一世纪可持续农业的建立。     

Relationship between Nature Reserve and Local Village,Baka Case

Local villagers have important effect on the biodiversity in the nature reserve as they take advantage of the source for hundreds of years. Baka, a Jinuo village was studies with market investigation and questionnaire, especially focused on the bene-fits and costs that risen from nature reserve. It is found that the local people get a large number of income from nature reserve, at the same time, local people lost opportunity costs for lost land where is turned to nature reserve. Suggestions are given to manage-ment and development of the nature reserve.