中华绒螯蟹幼蟹标准代谢的研究

对中华绒螯蟹幼蟹的耗氧率、CO2 排出率及NH3-N排泄率进行了测定 ,并研究了幼蟹的能耗率及能源物质的供能比。结果表明 ,体重 ( 2 70± 1 4 0 )g的幼蟹 ,在水温 ( 2 0± 0 5 )℃时 ,耗氧率、CO2 排出率和NH3-N排泄率分别为 ( 0 4 14± 0 0 91)mg·g-1·h-1、( 0 4 76± 0 12 5 )mg·g-1·h-1和 ( 4 179± 1 171) μg·g-1·h-1;标准代谢的蛋白质、碳水化合物和脂肪提供的能量比为 7 3∶3 8 8∶5 3 9。其耗氧率 (R0 )受水中溶氧水平的影响 ,并与体重(W )呈负相关 (R0 =0 84 0 3W-0 72 6 5)。     

河蟹过度放养对湖泊底栖动物群落的影响

通过对河蟹养殖的代表湖泊黄湖与参照水体即黄湖围栏外、天然捕捞湖泊龙感湖以及鱼类放养湖泊牛山湖的比较研究 ,探讨河蟹过度放养对湖泊底栖动物群落结构和功能的影响。结果表明 ,河蟹影响底栖动物群落的途径有两条 ,一是直接摄食 ,二是破坏沉水植物的间接作用。在蟹苗放养强度约 1kg·hm-2 的条件下 ,底栖动物的种类多样性明显下降 ,密度和生产量减少 6 0 %以上 ,其中对小型螺类的影响尤甚。作者认为目前最适的养殖模式应是河蟹与非草食性鱼类的轮作经营。     

放养河蟹对黑龙江东湖水库底栖动物和水生维管束植物的影响

在面积为2700hm2的东湖水库,以散养的方式养殖河蟹。在放养密度不同的情况下,研究放养河蟹对水库中底栖动物和水生植物的影响。2001年规格为220只/kg河蟹放养量为1500kg、密度为122只/hm2时,对摇蚊幼虫和寡毛类影响显著,而对其他软体动物和水生植物无显著影响。2002年同样规格的河蟹放养量增加至3500kg、密度为285只/hm2时,对底栖动物和部分沉水植物影响显著。本文对河蟹养殖容量作了讨论,认为东湖水库散养河蟹的放养量不应超过1500kg。       

七种捕食性鱼类对中华绒螯蟹幼蟹捕食风险的评估

分别以鲤、鳜、斑点叉尾、黄颡鱼、瓦氏黄颡鱼、大口鲇和乌鳢作为捕食者,以中华绒螯蟹幼蟹作为猎物,在室内水泥池(2.4 m3)进行捕食试验。以日捕获率和日摄食率为指标,评估这些鱼类对幼蟹的捕食作用和危害程度,为提高湖泊幼蟹放流效果、建立蟹—鱼复合的优质高效养殖模式提供科学依据。在幼蟹完全暴露的条件下,经过多次(至少9次)重复的试验(短期1d和长期7d),鳜对不同大小的硬壳和软壳(刚蜕壳的)幼蟹没有任何捕食作用;黄颡鱼对硬壳和软壳幼蟹也没有捕食作用,但还需做进一步观察;虽然鲤、瓦氏黄颡鱼对硬壳蟹的捕获率低,但对软壳的幼蟹有较大的危害性,对幼蟹的日摄食率分别为0.070%、0.012%;大口鲇、斑点叉尾、乌鳢对幼蟹具有较强的捕食能力,对幼蟹的日摄食率分别为0.122%、0.188%和0.284%。根据这些研究结果,可以建议:(1)在池塘和湖泊河蟹养殖中,完全可以将鳜作为套养或混养对象,以期提高养殖效益;(2)在河蟹放养的湖泊,需要抑制乌鳢和大口鲇种群,适当减少鲤和瓦氏黄颡鱼丰度,以期减少这些鱼类的捕食作用,提高幼蟹存活率;(3)在河蟹养殖池塘,不能放养乌鳢、大口鲇、斑点叉尾、瓦氏黄颡鱼和鲤。     

几种因素对白芦笋试管苗生根的影响

白芦笋的不同筛选株系之间生根能力存有差异;培养温度是影响生根率的关键因素,高温[≥(25±1)℃]不利生根,发根的适宜培养温度为(20±1)℃;低光照强度(≤25mmol·m-2·s-1)对生根不利,适宜的光合光量子通量密度(PPFD)为40μmol·m-2·s-1;PP333、嘧啶醇不能提高试管苗生根率,且浓度过高还会降低生根率和抑制植株生长。     

河蟹幼蟹溯江生态的研究

中华绒螯蟹(Eriocheir sinensis)俗称河蟹,属于溯江生长、降海繁殖的洄游性甲壳类。受精卵孵化后经溞状幼体、大眼幼体,而成幼蟹,在适宜的生态条件下,幼蟹溯江而上,进入河川、湖泊和池塘等淡水水域栖息生长。 研究河蟹的生物学规律,是河蟹资源增殖的客观根据。以往对河蟹幼蟹的溯江生态研究尚少,作者于1981—1982年,在长江的芜湖江段,对幼蟹的溯江生态进行多方面调查,现将芜     

椭圆萝卜螺Radix swinhoei (H. Adams) 对三种沉水植物的牧食选择

报道了2005年7～9月在太湖试验基地进行的椭圆萝卜螺对沉水植物牧食的实验结果.结果表明,椭圆萝卜螺对3种沉水植物的平均牧食率为7.87mg·g-1·d-1,其中对苦草的牧食率最高(13.63 mg·g-1·d-1),马来眼子菜次之(9.66mg·g-1·d-1),轮叶黑藻最低(0.31mg·g-1·d-1),且牧食率与螺规格呈显著负相关.椭圆萝卜螺对沉水植物的牧食具有选择性,喜食苦草而较少选食其他两种沉水植物.椭圆萝卜螺的食物选择性能力与其规格有关,随着生长对沉水植物的选择性加强.探讨了椭圆萝卜螺对沉水植物的选食机理.     

四十里湾栉孔扇贝清滤率、摄食率和吸收效率的现场研究

运用生物沉积法在四十里湾不同海区对栉孔扇贝的生理生态学特征进行了研究。 1龄栉孔扇贝 (4 1 .1± 4.1 mm,软体干重 0 .48± 0 .1 0 g/ ind)清滤率变化范围为 0 .72～ 2 .5 4(平均 1 .2 7) L/ (ind· h)或 1 .65～ 5 .97(平均 2 .61 ) L/ (g· h)。清滤率受 TPM的变化影响不大 ,而摄食率却随 TPM的升高而升高。 2龄扇贝 (软体干重 1 .91± 0 .3 2 g/ ind)清滤率为2 .0 9～ 3 .99(平均 3 .1 0 ) L/ (ind· h)。栉孔扇贝吸收速率与 POM呈正相关关系 ,而与饵料质量 (POM/ TPM)无明显的相关性。1龄扇贝和 2龄扇贝吸收效率没有显著差别 ;扇贝对 POM的吸收效率与 TPM (或 POM)关系不大 ,却与饵料质量呈明显的正相关关系 ;扇贝对 POC、PON和 PP的吸收效率平均分别为 68.9%、64.0 %和 63 .6%。在沿岸养殖海域 ,栉孔扇贝通过大量的滤水摄食以及较高的吸收效率对生态系统的能量流动和物质循环产生影响。     

鼎湖山苗圃和主要森林土壤CO2排放和CH4吸收对模拟N沉降的短期响应

研究了鼎湖山生物圈保护区苗圃(幼苗)、马尾松、混交林和季风常绿阔叶林(季风林)土壤CO2排放和CH4吸收的一些特征及其对模拟N沉降增加的响应.结果表明,土壤CO2日(白天)平均排放量的大小顺序为(平均值±标准误)苗圃(258±62mg·m-2·h-1)＞季风林(177±42 mg·m-2·h-1)＞马尾松林(162±39 mg·m-2·h-1)＞混交林(126±30 mg·m-2·h-1).土壤CH4日(白天)平均吸收量的大小顺序为马尾松林(-0.15±0.02 mg·m-2·h-1)＞季风林(-0.08±0.01 mg·m-2·h-1)＞混交林(-0.07±0.01 mg·m-2·h-1)＞苗圃(-0.05±0.01 mg·m-2·h-1).低N(50 kg N·hm-2·a-1)和中N(100kg N·hm-2·a-1)处理对苗圃、马尾松林和混交林样地土壤CO2日平均排放量的影响均不明显,高N(150 kg N·hm-2·a-1)处理对苗圃土壤CO2的日平均排放量也无显著影响,但倍高N(300kg N·hm-2·a-1)处理显著促进苗圃样地土壤CO2的排放.然而,所有N(低N、中N和高N)处理均显著促进季风林土壤CO2日平均排放量,且这种促进作用随N处理水平的升高而增加.N处理显著促进季风林和马尾松林土壤对CH4吸收速率,但对混交林土壤CH4吸收则无明显的影响.在苗圃样地,除倍高N外,N处理对土壤CH4吸收速率也无显著作用,但倍高N处理使苗圃土壤发生功能转变,即从CH4汇转变为CH4源.     

草毡寒冻雏形土CO2释放特征

研究了植物生长季节海北高寒草甸生态系统高寒嵩草草甸覆被下草毡寒冻雏形土的 CO2 释放速率。其结果表明 :CO2 释放速率有明显的日变化和季节动态。日最大排放速率多出现在 1 4 :0 0～ 1 6:0 0时 ,最小排放速率在 6:0 0～ 8:0 0时。植物生长季日最大振幅为 797.75mg/m2·h,最小振幅 1 97.33mg/m2·h。CO2 排放白天大于夜晚。不同物候期 CO2 释放速率不同 ,其顺序为草盛期 >枯黄期 >返青期。生长季土壤 CO2 释放速率的范围是 4 41 .72 mg/m2 · h± 1 55.2 9mg/m2· h,最大日均值为 681 .0 6mg/m2 · h( 7月 1 6日 ) ,最低值 1 76.65mg/m2 · h ( 6月 1日 )。退化草地土壤 CO2 释放速率明显低于未退化草地 ,生长季平均日均值低 1 37.4 7mg/m2·h。相关分析表明 :土壤 CO2 排放速率与气温、地表温度、土壤5cm、1 0 cm、1 5cm、2 0 cm、30 cm地温均呈显著和极显著相关关系。温度是影响土壤 CO2 释放速率的主要因子。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.