Eutrophication of Lakes Leman and Neuchâtel (Switzerland) indicated by oligochaete communities

In 1978–80, oligochaete communities of meso-eutrophic Lake Léman (Lake of Geneva) were compared to those of mesotrophic Lake Neuchâtel. Worm species were classified into three groups corresponding to their increasing tolerance to eutrophication: (1) oligotrophic species, mostly Peloscolex velutinus, Stylodrilus heringianus; (2) mesotrophic species, mostly Potamothrix vejdovskyi, P. bedoti; (3) eutrophic species, mostly Potamothrix hammoniensis, P. heuscheri, Tubifex tubifex. In both lakes, eutrophic species constituted the bulk of the communities in terms of absolute abundance. However, relative abundance of mesotrophic and eutrophic species was higher in Lake Léman; oligotrophic species were more important in Lake Neuchâtel. These data confirmed the trophic classification of lakes based on chemical parameters. The number of zero values, which perturbated statistical analysis, was reduced by using species groupings instead of isolated species. Thus, making the lakes more comparable even if different species were present in each one. Relative density values based on all samples were distributed among 4 density classes for the 3 species groupings. The 12 resulting frequencies described the community structure expressed in terms of eutrophication. Furthermore, these frequencies may be used for comparison of eutrophication levels in several lakes.     

Angiotensin biosynthesis and concentrations in brain of normotensive and hypertensive rats

We report here on the extraction and characterization of angiotensin I (ANG I) and angiotensin II (ANG II) from the brain of rats. High pressure liquid chromatography (HPLC) with different mobile phases combined with specific radioimmunoassays (RIA) proved to be a powerful tool for peptide characterization in biological samples; (Ile5)-ANG I, (Ile5)-ANG II and (Ile5)-ANG III could clearly be identified in cerebrospinal fluid (CSF), incubated in vivo and in vitro with renin, in total brain extracts, as well as in hypothalamus (HT), medulla oblongata (MO), cerebellum (CER) and cortex (CO). Angiotensin cleaved from CSF angiotensinogen and angiotensin extracted from brain showed retention times identical to those of plasma angiotensin and synthetic standard peptides, indicating that their amino acid sequence is probably identical. ANG I and ANG II were highest in the HT and lowest in the CO. Following bilateral nephrectomy (NX) both ANG I and ANG II persisted at control levels. Young 10 week old spontaneously hypertensive rats (SHRSP) showed significantly lower ANG I and ANG II concentrations in the HT compared with Wistar Kyoto rats (WKY). Intracerebroventricular (i.c.v.) administration of the converting enzyme inhibitor captopril caused a significant increase in ANG 1 in nephrectomized SHRSP but not in WKY. These differences were not found in 40 week old SHRSP. The data show that ANG I and ANG II are synthetized in the brain of rats. The lower concentrations and the enhanced accumulation of ANG I after converting enzyme blockade in nephrectomized young SHRSP indicate an increased turnover of angiotensin in hypertensive rats.     

Use of agar-based diet to fulfil the food and water requirements of mice

Mice were fed an agar-based diet without an additional source of water for 5 weeks. In comparison with a similar group of mice fed a commercial diet and water ad libitum, there were no significant changes in bodyweight.     

Passive Transfer of Lambert-Eaton Myasthenic Syndrome in Mice: Decreased Rates of Resting and Evoked Release of Acetylcholine from Skeletal Muscle

Mice were injected for 1-2 months daily with 10 mg immunoglobulin G (IgG) from four patients with Lambert-Eaton myasthenic syndrome (LEMS); control mice were injected with pooled human IgG from normal donors. Gastrocnemius muscles were homogenised for the assay of acetylcholine (ACh), choline acetyltransferase (ChAT), and cholinesterase (ChE). The ACh, ChAT, and ChE contents of gastrocnemius muscles from "LEMS mice" were about the same as the control values, which were 180 pmol, 40 nmol X h-1 (37 degrees C), and 15 mumol X h-1 (37 degrees C), respectively. Hemidiaphragms were treated with an irreversible ChE inhibitor (Soman) and incubated at 20 degrees C for estimation of ACh release. Resting ACh release from experimental muscles was reduced by about 25% (P2 less than 0.05) and the release evoked by 3 s-1 nervous stimulation by 50% (P2 less than 0.05). On the other hand, 50 mM KCl-induced transmitter release was not abnormal in LEMS mice. The findings indicate that IgG antibody from patients with LEMS may bind to nerve terminal determinants that are involved in quantal and nonquantal ACh release.     

Electron microscopy of bacteriophage phi 6 nucleocapsid: three-dimensional image analysis.

Electron micrographs of bacteriophage phi 6 nucleocapsids, negatively stained by neutralized phosphotungstate and tilted in a goniometer specimen cartridge, proved that the three distinct morphologies seen in the electron microscope are merely three different aspects of a single nucleocapsid structure and strongly suggested that this structure is dodecahedral.     

鄱阳湖水生植被

本文列出了鄱阳湖98种水生维管束植物的名录,叙述了水生植被的分布。鄱阳湖水生植被面积为2262平方公里,占全湖总面积的80．8％。湖中植被呈不规则环带状分布,并可划分为湿生、挺水、浮叶和沉水4个植物带,9个主要植物群丛。并研究了鄱阳湖水生植被的演变及发展趋势和湖水位的季节性变化对植被的影响。     

鄱阳湖水生维管束植物生物量及其合理开发利用的初步建议

用4种不同的计算方法测定了鄱阳湖水生维管束植物的生物量。根据22个断面,199个采集点,398个样方的测定结果,得出鄱阳湖水生维管束植物的年生产量为431.76万吨(湿重),即相当于5.44×10~(-15)焦耳(能量)。其中,马来眼子菜、苦草和黑藻等3种合计约占总生物量的71.46%。全湖可供草食性鱼类食用的水生维管束植物约占总量的86.9%。文中还对4个植物带和9个群丛生物量的分布规律进行了讨论。提出了人工增殖草食性鱼类,调整湖中植被组成,保护和种植水生经济植物等合理开发利用鄱阳湖水生植物资源的初步建议。     

龙葵抗阿特拉津生物型叶绿体基因文库的建立

用对阿特拉津(Atrazine)除草剂抗性的龙葵生物型B_(12)株系作材料,制备叶绿体DNA。B_(12)株ctDNA(叶绿体DNA)经BamHI酶解,在0.7％琼脂糖凝胶电泳上呈现24条带,其中最大的片段为18.6kb,最小的片段为1kb。用pBR322作为载体,构建B_(12)株ctDNA BamHI片段文库。通过与探针的分子杂交,从中筛选出含有编码叶绿体32kd蛋白质的阿特拉津抗性基因的克隆pSB135和含有ATP合酶α亚单位基因的克隆pSB132。     

Formation of cellobiose lipids by growing and resting cells of Ustilago maydis

Summary Utilizing coconut oilUstilago maydis ATCC 14826 synthesizes cellobiose lipids under N-limitation conditions and as resting cells, which gave the highest specific biosurfactant production (0.79 g/g substrate). C6-, C12-, C14-, and 15, 16-dihydroxy-C16-fatty acids are the main components of the lipophilic moiety of these glycolipids.     

红皮树胚胎发育

本文报道红皮树(Styrax suberifoltus Hook.et Arn.)大小孢子发育和早期胚胎发生。子房具胚珠20—23枚,胚珠横生,珠被二层,薄珠心,孢原细胞直接起大孢子母细胞作用。合点端大孢子具功能。胚囊发育为正常型。成熟胚囊具大量淀粉粒。小孢子形成为同时型,成熟花粉为二细胞型。传粉后、受精前两个助细胞在形状和对苏木精着色程度上有显著区别。胚乳发育为细胞型。在合子分裂前,胚乳细胞增至约26个时,暂时停止分裂。苏木精对细胞质不易着色,似解体细胞。有胚乳吸器。