鱼类染色体G—显带的Brd U—BSG方法及白鲢G—带模式图的初步建立

本文报道了一种显示鱼类染色体G-带的BrdU-BsG方法。采用肾细胞短期培养,收获前12小时加入BrdU,使终浓度为10μg/ml。制片经HCl、Ba(OH)_2处理,4×SSC温育。Giemsa染色,显示出白鲢的G-带。其带纹细致清晰,一个细胞的单倍染色体上显示带纹达200条以上,是目前已报道的鱼类多重带中带纹最多的,且反差明显,带纹有特征性,结果较稳定。根据实验结果初步建立了白鲢的G-带模式图。     

Assembly and disassembly of brain tubulin is affected by high ammonia levels

Rats were fed a diet containing ammonium for up to 6 months. High ammonia levels were attained in brain. The amount of polymerized tubulin in microtubules increased, while the amount of free tubulin remained unchanged. Polymerization of tubulin from brain of ammonium fed rats (30 min, 37°C) was approximately 60% of control. Depolymerization of the microtubules was also affected and took approximately 3 times longer than in controls. These results indicate that both assembly and disassembly of tubulin in brain are impaired by high ammonia levels. Interestingly, the amount of microtubule-associated proteins was not affected.     

A protein-free diet changes synaptosomal membrane fluidity and tyrosine and glutamate transport

Synaptosomes were isolated from cerebrums of rats fed standard (20% protein) or protein-free diets for 30 days. Arrhenius plots of their (Na⁺/K⁺)ATPase activities revealed a transition temperature of 25.5°C for control rats and 23.4°C for rats on protein-free diet, indicating that the latter increases synaptosomal membrane fluidity. The only change observed in the composition of the synaptosomal membranes was a 26% decrease of sialic acid. In synaptosomes from rats on protein-free diet the uptake of tyrosine was slightly reduced while that of glutamate was not affected. However, the exit of glutamate was reduced.     

野生大豆基因文库的构建

以氯化铯密度梯度离心法纯化噬菌体λEMBL4,将纯化的EMBL4 DNA用BamH1/SalI双酶切制成载体。用CTAB(十六烷基三甲基溴化铵)法提取野生大豆(种名待定)大分子DNA,Sau3A部分酶解,从琼脂糖凝胶中回收10—22kb“目的”DNA片段,与载体连接,体外包装成重组噬菌体。所得重组子值为8×10(?)pfu(噬菌斑形成单位),达到了构建野生大豆基因文库要求的理论值。以栽培大豆7S贮藏蛋白a′-cDNA作探针,用噬菌斑原位杂交法从文库中筛选出一个阳性克隆。     

NMDA Receptor antagonists prevent acute ammonia toxicity in mice

We proposed that acute ammonia toxicity is mediated by activation of NMDA receptors. To confirm this hypothesis we have tested whether different NMDA receptor antagonists, acting on different sites of NMDA receptors, prevent death of mice induced by injection of 14 mmol/Kg of ammonium acetate, a dose that induces death of 95% of mice. MK-801, phencyclidine and ketamine, which block the ion channel of NMDA receptors, prevent death of at least 75% of mice. CPP, AP-5, CGS 19755, and CGP 40116, competitive antagonists acting on the binding site for NMDA, also prevent death of at least 75% of mice. Butanol, ethanol and methanol which block NMDA receptors, also prevent death of mice. There is an excellent correlation between the EC₅₀ for preventing ammonia-induced death and the IC₅₀ for inhibiting NMDA-induced currents. Acute ammonia toxicity is not prevented by antagonists of kainate/AMPA receptors, of muscarinic or nicotinic acetylcholine receptors or of GABA receptors. Inhibitors of nitric oxide synthase afford partial protection against ammonia toxicity while inhibitors of calcineurin, of glutamine synthetase or antioxidants did not prevent ammonia-induced death of mice. These results strongly support the idea that acute ammonia toxicity is mediated by activation of NMDA receptors.     

Rapid screening of an SH2-containing gene using PCR amplification method

Summary To isolate a novel gene that contains an SH2 domain, we devised a rapid and nonradioactive cDNA library screening method using polymerase chain reaction (PCR). For PCR amplification, we designed degenerate oligonucleotide primers from the multialigned DNA sequences of SH2 domains. This method offers an inexpensive and efficient approach for the isolation of clones of interest from cDNA libraries.     

REGENERATION AND SEXUAL DIFFERENTIATION OF GRIFFITHSIA JAPONICA (CERAMIACEAE,RHODOPHYTA) THROUGH SOMATIC CELL FUSION1

Hybrid cells were obtained from somatic cell fusion among male, female, and tetrasporangial plants in Griffithsia japonica Okamura by a wound-healing process. Isolated fusion cells regenerated new mature plants with mixed reproductive structures. The plants regenerated from hybrid cells between male and female plants developed into 1) spermatangiate, 2) carpogonial, 3) bisexual with spermatangia and carpogonial branches, 4) mixed-phase with spermatangia and tetrasporangia, or 5) bisexual/mixed-phase plants with spermatangia, carpogonial branches, and tetrasporangia. About 70% of the plants regenerated from hybrid cells between male and female plants produced tetrasporangia that were always formed with spermatangia on a single cell. Some of those tetrasporangia released tetraspores, six of which gave rise to mature plants. The plants regenerated from hybrid cells between male and tetrasporangial plants developed into spermatangiate, tetrasporangiate, or mixed-phase plants with spermatangia and tetrasporangia. The plants regenerated from hybrid cells between female and tetrasporangial plants developed into carpogonial, tetrasporangiate, or mixed-phase plants with carpogonial branches and tetrasporangia. All types of reproductive structures we re functional.     

瑞氏七鳃鳗乳酸脱氢酶（LDH）同工酶凝胶电泳分析

本文用聚丙烯酰胺凝胶电泳方法,对瑞氏七鳃鳗五种不同组织（骨骼肌、心、肾、肠、鳃）中ＬＤＨ同工酶进行了分析研究,结果表明,ＬＤＨ同工酶具有组织特异性,其中骨骼肌中含有五种ＬＤＨ同。酶,即ＬＤＨ１、ＬＤＨ２、ＬＤＨ３、ＬＤＨ４、ＬＤＨ５,鳃含有ＬＤＨ１和ＬＤＨ４而肾和心只含有ＬＤＨ１,肠只含有ＬＤＨ４。