弱光照和富营养对苦草生长的影响

本研究通过比较在不同光照和营养(3光照×3营养)水平下栽培的沉水植物苦草(Vallisneria natansL.)的生长及生化指标,探讨了富营养水体中弱光和高营养对苦草生长的影响。结果表明:弱光对苦草生长的抑制作用不受外源营养浓度的影响;而高营养对苦草生长的影响受到弱光胁迫程度的交互作用,表现为在光照较强的45%日光下为抑制作用,光照最弱的2.5%日光下为促进作用,在光强居间的10%日光下没有明显作用。植物组织总氮、总磷、氨态氮及游离氨基酸氮含量随光照减弱而增加,而可溶性总糖和淀粉含量减少;总磷、氨态氮

彩鲫hira基因片段的克隆及表达分析

hir/hira基因最先作为组蛋白基因表达的一种负调节因子从酵母中被鉴定出来。现已证实,HIRA包含一组保守的蛋白家族,广泛存在于低等真核生物、无脊椎动物和脊椎动物等多种生物体当中,为生命发育所必需。关于hira基因在动物发育过程中的具体作用研究还不是很多,为了进一步探讨hira基因在鱼类发育过程中的作用,作者根据已知hira基因保守序列设计一对简并引物,分别以彩鲫基因组DNA和卵巢cDNA为模板克隆了彩鲫hira基因(Cahira)片段,该片段基因组序列为2181bp,基因组片段含有6个内含子,长度分别

车轮虫齿体特征的量化及其种内种间系统发育的研究

齿体特征是车轮虫物种鉴定的一个重要依据。本文首次提出一种齿体结构面积比例量化法 ,即通过对齿钩、齿锥、齿棘、齿体环各部分反口面观面积的测量 ,分别计算出前三者与所在齿体的面积比以及所有齿体总面积与齿体环的面积比 ,从而将齿体特征转换为量化指标。依据所测量化值 ,采用相似性聚类法 ,我们首先探讨了显著车轮虫 (TrichodinanobbillisChen ,196 3)的三个种群的亲缘关系 ,然后以劳牧小车轮虫 (TrichodinellalomiXu ,Song&Warren ,1999)为外类群 ,选

中国囊裸藻属的新种类

国家自然科学基金

再论白暨豚和江豚的保护

白暨豚（Ｌｉｐｏｔｅｓｖｅｘｉｌｉｆｅｒ）的种群数量已降到了很低的水平，濒临灭绝，长江的自然环境，由于人类活动的加剧而日趋恶化。长江环境已经不可能保存白暨豚，但可能在一个半自然保护区保存下来。中国政府正在考虑集中人力和财力优先建设一个最好的白暨豚半自然保护区，即石首天鹅洲白暨豚半自然保护区，因为目前白暨豚的种群现状已不可能支持１个以上的半自然保护区。１头成熟的雌性白暨豚已于１９９５年捕获并移入石首天鹅洲保护区。江豚（Ｎｅｏｐｈｏｃａｅｕａｐｈｏ－ｃａｅｎｏｉｄｅｓ）也面临着白暨豚所面临的全部威胁。近年来其

团藻目新资料

本文报道湖北省武汉市团藻目7个属的5个新种,2个新变种,2个中国新记录

珞珈山森林土壤原生动物生态学研究及土壤原生动物定量方法探讨

１９９３年１月至１２月，用直接计数法和培养计数法对武昌珞珈山森林土壤原生动物进行了周年定量研究，发现原生动物丰度的周年动态趋势为：春季（３—５月）达到高峰，低谷出现在冬季（１—２月），夏秋季保持较平稳的变动。原生动物丰度与土壤环境因子间的相关性分析结果表明，原生动物丰度的周年动态与土壤含水量及土壤ｐＨ值的变化呈显著的正相关，与土壤温度的变化无明显相关关系。珞珈山森林土壤原生动物优势种为梨波豆虫（Ｂｏｄｏｅｄａｘ）、球波豆虫（Ｂｏｄｏｇｌｏｂｏｓｕｓ）、卵形隐滴虫（Ｃｒｙｐｔｏｍｏｎａｓｏｖａｔａ）、长尾尾

中华双腔吸虫精子发生的超微结构研究

应用透射电镜技术，研究中华双腔吸虫（Ｄｉｃｒｏｃｏｅｌｉｕｍ ｃｈｉｎｅｓｉｓ Ｔａｎｇ ｅｔ Ｔａｎｇ １９７８）的精子发生， 并与其它复殖吸虫进行比较，提出了复殖吸虫精子发生的一般过程，结果显示它与大多数复殖吸虫 精子发生的超微结构相似，原始的精原细胞经过三次有丝分裂，两次减数分裂成为精细胞，它经过 分化、形态变化后成为成熟精子，精子形成共分为六个阶段，其中有以下首次报道的特征：（１）中 央胞质区的生长速度在开始时比鞭毛要快；（２）在鞭毛与中央胞质区融合前，线粒体的前端在中央 胞质区中有段时间比核更接

Statistics anxiety, state anxiety during an examination, and academic achievement.

BACKGROUND: A large proportion of students identify statistics courses as the most anxiety-inducing courses in their curriculum. Many students feel impaired by feelings of state anxiety in the examination and therefore probably show lower achievements. AIMS: The study investigates how statistics anxiety, attitudes (e.g., interest, mathematical self-concept) and trait anxiety, as a general disposition to anxiety, influence experiences of anxiety as well as achievement in an examination. SAMPLE: Participants were 284 undergraduate psychology students, 225 females and 59 males. METHODS: Two weeks prior to the examination, participants completed a demographic questionnaire and measures of the STARS, the STAI, self-concept in mathematics, and interest in statistics. At the beginning of the statistics examination, students assessed their present state anxiety by the KUSTA scale. After 25 min, all examination participants gave another assessment of their anxiety at that moment. Students' examination scores were recorded. Structural equation modelling techniques were used to test relationships between the variables in a multivariate context. RESULTS: Statistics anxiety was the only variable related to state anxiety in the examination. Via state anxiety experienced before and during the examination, statistics anxiety had a negative influence on achievement. However, statistics anxiety also had a direct positive influence on achievement. This result may be explained by students' motivational goals in the specific educational setting. CONCLUSIONS: The results provide insight into the relationship between students' attitudes, dispositions, experiences of anxiety in the examination, and academic achievement, and give recommendations to instructors on how to support students prior to and in the examination.

以底栖动物评价湘江污染的研究

湘江底栖动物种类较丰富,而上游种类尤多,生物多样性明显。中、下游某些江段因污染等因素影响,多样性有差异。shannon多样性指数反映出了这些变化。上游江段属于清洁水体,中、下游多数江段属于轻污染,少数江段为中污染,而霞湾港江段为重污染。进行了水和底泥中化学毒物的含量与生物主要种类的数量变化的相关分析。

粘孢子纲新科的代表——安永七囊虫SEPTEMCAPSULA YASUNAGAI,新属新种

<正> 日本国安永统男先生(Norio Yasunaga, 1981)报道在日本长崎五岛一些养殖场饲养的花鲈 Lateolabrax japonicus发生一种粘孢子虫病,引起严重死亡。他从病鱼脑腔里找到这种病原体的孢囊标本,赠给作者两块,以研究它的形态结构和分类问题。通过对标本的详细观察、研究,认为这种粘孢子虫的孢子,形态结构比较特殊,不仅足以作为独立的属,而且是一新科的代表。

Effects of arsenate on the growth and microcystin production of Microcystis aeruginosa isolated from Taiwan as influenced by extracellular phosphate

Arsenic pollution and eutrophication are both prominent issues in the aquaculture ponds of Taiwan. It is important to study the effects of arsenic on algal growth and toxin production in order to assess the ecological risk of arsenic pollution, or at least to understand naturally occurring ponds. The sensitivity of algae to arsenate has often been linked to the structural similarities between arsenate and phosphate. Thus, in this study we examined the effects of arsenate (10(-8) to 10(-4) M) on Microcystis aeruginosa TY-1 isolated from Taiwan, under two phosphate regimes. The present study showed that M. aeruginosa TY-1 was arsenate tolerant up to 10(-4) M, and that this tolerance was not affected by extracellular phosphate. However, it seems that extracellular phosphate contributed to microcystin production and leakage by M. aeruginosa in response to arsenate. Under normal phosphate conditions, total toxin yields after arsenate treatment followed a typical inverted U-shape hormesis, with a peak value of 2.25 +/- 0.06 mg L-1 in the presence of 10(-7) M arsenate, whereas 10(-8) to 10(-6) M arsenate increased leakage of similar to 75% microcystin. Under phosphate starvation, total toxin yields were not affected by arsenate, while 10(-6) and 10(-5) M arsenate stimulated microcystin leakage. It is suggested that arsenate may play a role in the process of microcystin biosynthesis and excretion. Given the arsenic concentrations in aquaculture ponds in Taiwan, arsenate favors survival of toxic M. aeruginosa in such ponds, and arsenate-stimulated microcystin production and leakage may have an impact on the food chain.

Induction of hepatic cytochrome P4501A1/2B activity and disruption of thyroglobulin synthesis/secretion by mono-ortho polychlorinated biphenyl and its hydroxylated metabolites in rat cell lines

As the active metabolites of polychlorinated biphenyl (PCBs), hydroxylated polychlorinated biphenyls (OH-PCBs) are found in wildlife and human tissues. They have been proposed as main contributors for endocrine disruption of PCBs in living organisms. In this study, mono-ortho PCB 156 and its hydroxylated metabolites 4'-OH-PCB 159, 4'-OH-PCB 121, and 4'-OH-PCB 72 were selected to investigate the toxic effects on rat hepatoma H4IIE cell line and rat thyroid follicle FRTL-5 cell line at concentrations of 1, 10(2), 10(4) nM. 7-Ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) activities were determined with micro-EROD/PROD to indicate cytochrome P4501 A1 (CYP1A1) and cytochrome P4502B (CYP2B) induction in the H4IIE cell after exposure for 72 h. To assess thyroid disruption of these compounds, thyroglobulin concentrations also were detected inside FRTL-5 cell with immunocellularchemistry and in its medium with radioimmunoassay after exposure for 24 It. Significant inductions of EROD activity by PCB 156 at 102 and 104 nM (p < 0.05) were observed, but no effects by the three OH-PCBs in H4IIE cell line. 7-Pentoxyresorufin-O-dealkylase activities were induced only by 10(4) nM of PCB156 and the three OH-PCBs (p < 0.05). Meanwhile, significant increases of thyroglobulin concentrations were observed in the medium of FRTL-5 cell exposed to 4'-OH-PCB 121 and 4'-OH-PCB 72 at all of the test concentrations (p < 0.05), but not to the other compounds. The results demonstrated that mono-ortho PCBs mainly could be metabolized to hydroxylated metabolites through CYP1A1 instead of CYP2B. Moreover, after being metabolized, OH-PCBs still sustained the ability to induce PROD activity and did exhibit the disruption on thyroglobulin synthesis/excretion in rat cells.

Monitoring of organochlorine pesticides using PFU csystems in Yunnan lakes and rivers, China

Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids, were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GCECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 mu g l(-1) (mean 0.27 mu g l(-1)), undetectable to 0.72 mu g l(-1) (mean 0.11 mu g l(-1)), and 0.24-21.95 mu g l(-1) (mean 7.39 mu g l(-1)) respectively in lakes; and those in rivers were undetectable to 0.23 mu g l(-1) (mean 0.08 mu g l(-1)), 0.68-2.93 mu g l(-1) (mean 1.70 mu g l(-1)), and 2.71-37.56 mu g l(-1) (mean 17.01 mu g l(-1)) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination. (c) 2006 Elsevier Ltd. All rights reserved.