白蚁化石的地理分布及其演变

在地球的地质变迁中, 白蚁类群的祖先, 因古地理、古气候和古生物变动的影响, 其地理分布逐渐由高纬度向低纬度、由干冷地区向湿热地区变动. 在漫长的历史演变过程中, 一些属种遭到灭绝; 一些属种在新的古生态环境中, 演化成新的类群; 一些属种则得以存留下来, 且延续生存至今。

Reversible disconnection of the hippocampal-prelimbic cortical circuit impairs spatial learning but not passive avoidance learning in rats

Wistar rats, treated with the GABA(A) receptor agonist muscimol, were used to investigate the role of the hippocampal-prelimbic cortical (Hip-PLC) circuit in spatial learning in the Morris water maze task, and in passive avoidance learning in the step-thr

膜生物反应器-复合垂直流人工湿地(SMBR-IVCW)系统处理混合废水的应用研究

本文采用一体式膜生物反应器(SMBR)-复合垂直流人工湿地(IVCW)组合工艺(SMBR-IVCW)系统,研究了该系统对复合废水的净化效果。结果表明,当系统进水为CODCr397～890mg.L-1、氨氮9.40～27.1mg.L-1、TP4.30～10.7mg.L-1、TN45.9～75.8mg.L-1的条件下,在SMBR和IVCW的水力负荷分别为1000L.d-1和375mm.d-1的最优工况下运行,系统CODCr、NH3-N、TN和TP的去除率分别为97.5%、99.0%、59.6%和65.2%;系

银鲫原肠胚差异表达基因的筛选

胚胎发育是基因组中各个基因在时间和空间上选择性表达的结果。为了鉴定参与鱼类早期胚胎发育和胚层分化的调控因了,分别构建了银鲫(Carassiusauratusgibelio)原肠胚和成熟卵子的SMARTcDNA文库,并采用差异筛选的方法,从银鲫原肠胚SMARTcDNA文库中筛选不同于成熟卵子的差异表达基因。通过菌斑和PCR产物的两轮斑点杂交,从大约1500个克隆中筛选出131个阳性克隆,从中选择58个克隆测序并将测得的序列进行了数据库比对分析,结果显示这些差异表达基因大部分为参与转录和翻译的调控因子和核糖体

微囊藻毒素分子致毒机理研究近况

<正> 目前,日趋严重的水体富营养化使水华发生已成为全球性环境问题,产生水华的藻类因而也受到越来越多的重视。海洋赤潮中甲藻所产生的毒素已引起人类的严重的中毒事件,虽然淡水水华还未发现引起人类急性中毒事件,但由于饮用发生水华水体的水而导致家畜、家禽及野生动物死亡的事件频繁发生,淡水水华已引起科学家的关注。微囊

白鱀豚脑的解剖

作者对采自长江的三头白鱀豚(Lipotes vexillifer Miller)的脑进行了解剖研究。白鱀豚的脑表现出典型的鲸脑特征。与海洋齿鲸类比较,淡水鲸科的种类普遍呈现出视觉系统的退化,这是一种生态适应的结果。从神经解剖学的观点看来,白鱀豚与亚马逊河海豚(Inia)、拉普拉塔河海豚(Pontoporia)的脑的结构是近似的,而与恒河海豚(Platanista)显著不同,这与骨骼形态上表现出的系统发育关系是一致的。

Expression pattern of cellular nucleic acid-binding protein (CNBP) during embryogenesis and spermatogenesis of gibel carp

By differential screening, we cloned the CagCNBP, demonstrated its predominant expression in ovary and testis, and reported its development behavior during folliculogenesis and oogenesis by immunofluorescence localization (Liu and Gui, Gene 365:181-192, 2005), but its developmental behavior during spermatogenesis and its transcript distribution during embryogenesis are not revealed. In the present study, by in situ hybridization, we analyze CagCNBP expression pattern during gibel carp embryogenesis. The CagCNBP transcripts ubiquitously distributed in all embryonic cells in early developmental stage embryos, and peak in midbrain, hindbrain and somites of gibel carp larva during organogenesis. By antibody detection, we reveal CagCNBP protein distribution change during spermatogenesis. The cell-specific distribution of CagCNBP is revealed by immunofluorescence staining, and predominant CagCNBP expression in testis somatic cells and spermatogonia is demonstrated in this paper. For the first time, the CNBP distribution during spermatogenesis in vertebrate has been revealed.

Enhanced protection against oxidative stress in an astaxanthin-overproduction Haematococcus mutant (Chlorophyceae)

Many unicellular green algae can become yellow or red in various natural habitats due to mass accumulation of a secondary carotenoid, such as lutein, or astaxanthin. The accumulation of secondary carotenoids is generally thought to be a survival strategy of the algae under photo-oxidative stress or other adverse environmental conditions. The physiological role of the carotenoids in stress response is less well understood at the subcellular or molecular level. In this study, a stable astaxanthin overproduction mutant (MT 2877) was isolated by chemical mutagenesis of a wild type (WT) of the green microalga Haematococcus pluvialis Flotow NIES-144. MT 2877 was identical to the WT with respect to morphology, pigment composition, and growth kinetics during the early vegetative stage of the life cycle. However, it had the ability to synthesize and accumulate about twice the astaxanthin content of the WT under high light, or under high light in the presence of excess amounts of ferrous sulphate and sodium acetate. Under stress, the mutant exhibited higher photosynthetic activities than the WT, based on considerably higher chlorophyll fluorescence induction, chlorophyll autofluorescence intensities, and oxygen evolution rates. Cell mortality caused by stress was reduced by half in the mutant culture compared with the WT. Enhanced protection of the mutant against stress is attributed to its accelerated carotenogenesis and accumulation of astaxanthin. Our results suggest that MT 2877, or other astaxanthin overproduction Haematococcus mutants, may offer dual benefits, as compared with the wild type, by increasing cellular astaxanthin content while reducing cell mortality during stress-induced carotenogenesis.

In situ studies on physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms in a large Chinese lake

Physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms were studied in a large net cage in Meiliang Bay, a hypereutrophic region of Lake Taihu. We sampled four fishes: the phytoplanktivorous Hypophthalmichthys molitrix and Aristichthys nobilis, the omnivorous Carassius auratus, and the carnivorous Culter ilishaeformis. Alterations of the antioxidant (GSH) and the major antioxidant enzymes (CAT, SOD, GPx, GST) in livers were monitored monthly, and the ultrastructures of livers were compared between the bloom and post-bloom periods. During the cyanobacterial blooms, the phytoplanktivorous fishes displayed only slight ultrastructural changes in liver, while the carnivorous fish presented the most serious injury as swollen endomembrane system and morphologically altered nuclei in hepatocytes. Biochemically, the phytoplanktivorous fishes possessed higher basal GSH concentrations and better correlations between the major antioxidant enzymes in liver, which might be responsible for their powerful resistance to MCs. This article provided physiological and toxicological evidences for the possible succession of fish communities following occurrence of toxic cyanobacterial blooms and also for the applicability of using phytoplanktivorous fish to counteract toxic cyanobacterial blooms in natural waters. (C) 2007 Elsevier Ltd. All rights reserved.