Distribution and disappearance of the radiolabeled carbon derived from L-arginine and taurine in the mouse

L-arginine and taurine are still in the center of physiological and pharmacological research. Although the fate of nitrogen of both compounds and of the ³⁵S-taurine is well-documented, the fate of the carbon skeleton has not been elucidated yet. We studied the organ distribution of ¹⁴C arginine and ¹⁴C taurine over time in the mouse using whole body autoradiography with densitometric image analysis. We describe different organ distribution patterns. Kidney, heart, lung, the Harderian gland, the central nervous system, intestine and testis showed a comparable pattern of arginine disappearance in contrast to rapid disappearance in the salivary gland and the accumulation pattern in bone and spleen. Data on ¹⁴C taurine of liver, kidneys, lung, testis and Harderian gland resembled the arginine pattern; Accumulation of taurine carbon was found in salivary gland, bone, intestine, heart and brain. Our studies challenge and demand further related studies to obtaining more information on the fate of the carbon skeleton of these amino acids.     

母牛分枝杆菌制剂对T淋巴细胞增殖反应影响的研究

以氚标记胸腺嘧啶核苷(~3H-TdR)掺入法检测每分钟脉冲数(CPM),比较母牛分枝杆菌活菌悬液、辐射杀死菌悬液及高温杀死菌悬液对健康人外周血T淋巴细胞增殖反应的影响.以此作为评价治疗以细胞介导免疫为主的结核病免疫功能障碍免疫制剂效力的一个重要参数.在加入单一刺激因子实验中,对照组CPM为448±131;加入BCG、母牛分枝杆菌活菌悬液、辐射杀灭菌悬液以及高温杀死菌悬液的CPM分别为1037±194,2299±140,1819±528,994±186.这4种制剂的刺激指数均在2.0以上,尤其是母牛分枝杆菌活菌悬液、辐射杀死菌悬液分别为5.13,4.06.结果表明,母牛分枝杆菌3种制剂与BCG基本相似,在体外对T淋巴细胞增殖反应有明显的促进作用,其中以活菌悬液和辐射杀死菌悬液更为显著.另一试验中,以重组白细胞介素-2(rIL-2)作对照,BCG、母牛分枝杆菌悬液、辐射杀死菌悬液及高温杀死菌悬液分别加入rIL-2,目的在于观察菌体抗原加淋巴因子对T淋巴细胞增殖反应有无协同刺激作用.对照组的CPM为3721±1336,BCG加rIL-2组CPM为6904±1218;母牛分枝杆菌3种制剂的CPM分别为9544±172…     

抗杀螟硫磷二化螟的抗性遗传力研究

应用数量遗传学的方法分析了水稻二化螟(chilo suppressalis)对杀螟硫磷抗药性的遗传力,并就遗传力和杀虫剂的杀死率对抗性发展速率的影响进行了预测。研究结果表明：二化螟对杀螟硫磷抗性的遗传力较低(h²＝0.277),产生高抗性的潜力不大。即使在室内选择的条件下,要获得10倍的抗性约需要6-12代;在野外条件下则需要更长的时间(15-32代)。因此,结合抗性变化动态的监测结果,我们认为在野外条件下二化螟是不致于产生高抗性,杀螟硫磷仍不失为二化螟抗性治理系统中有效品种之一。     

高必需氨基酸转基因马铃薯的研究

８０年代以来,马铃薯遗传转化系统日趋成熟,转基因工程植株已被广泛应用于基础科学研究［１］。作为食物蛋白和能量主要来源的马铃薯,提高其蛋白质含量及质量的遗传工程研究正受到人们的普遍关注［２］。Ｙａｎｇ等［２］将旨在改善氨基酸平衡的ＣＡＴ－ＨＥＡＡＥ（氯酶素乙酰转移酶－高含量人体必需氨基酸）融合基因导入马铃薯,获得了Ｓｏｕｔｈｅｒｎｂｌｏｔ、Ｎｏｒｔｈｅｒｎｂｌｏｔ、Ｗｅｓｔｅｒｎｂｌｏｔ的证据,但尚缺少氨基酸分析的资料。玉米醇溶蛋白（ｚｅｉｎ）［３］是一个富含甲硫氨酸的贮存蛋白,它和人工合成的ＨＥ…     

干旱和湿润生境下辽东栎群体遗传结构及其适应意义的初步研究

应用同工酶分析方法,测定北京市东灵山区两个分别代表干旱和湿润生境的辽东栋（ＱｕｅｒｃｕｓｌｉａｏｔｕｎｇｅｎｓｉｓＫｏｉｚ．）群体的遗传结构。共分析统计了１３ 个酶系统３０ 个位点。结果表明：辽东栎群体内部存在丰富的遗传变异（多态位点百分率为８６．６％ ,等位基因平均数为２．２５）。两群体遗传结构的相似性程度很高（Ｄ＝ ０．０２９, ＧＳＴ＝ ０．０４８）;但在个别位点上仍存在较大差异,这些差异的产生可能与对小生境的适应有关。对不同年龄段的初步分析结果显示,基因频率的动态变化可能有其适应意义     

杨树新品种叶肉原生质体培养和植株再生

从１ 个月龄的ＮＬ－８０１０６ 杨（Ｐｏｐｕｌｕｓｄｅｌｔｏｉｄｅｓ×Ｐ． ｓｉｍ ｏｎｉｉ）无菌苗叶片分离得到大量原生质体,纯化后其原生质体产量为４×１０７／ｇ ｆｒ．ｗ ｔ． 纯化的原生质体在含２,４－Ｄ ２ ｍ ｇ／Ｌ、ＮＡＡ ０．５ ｍ ｇ／Ｌ和ＫＴ ０．５ ｍ ｇ／Ｌ的ＫＭ８ｐ 和ＭＳ培养基中进行高密度液体浅层培养,渗透势为０．４０ ｍ ｏｌ／Ｌ的ＫＭ８ｐ 培养基中原生质体分裂频率最高． 培养第５ 天观察到第一次细胞分裂,培养１０ ｄ 的分裂频率为４．５％ ,１２ 周内可形成大量的细胞团和小愈伤组织． ＮＬ－８０１０６杨叶肉原生质体在富含有机氮并以葡萄糖为碳源的培养基中具有较高的分裂频率和植板率．小愈伤组织在ｇｅｌｒｉｔｅ 固化的ＮＬＺ１ 培养基上增殖生长,３ 周后形成４—６ ｍ ｍ 结构紧密的鲜红色愈伤组织,转至ＮＬＦ分化培养基,分化成苗率为１００％ ． 待芽伸长到３ ｃｍ 时,从基部切下转至１／２ ＭＳ培养基上诱导生根,形成完整植株     

Crystallization,molecular replacement solution,and refinement of tetrameric β-amylase from sweet potato

Sweet potato β-amylase is a tetramer of identical subunits, which are arranged to exhibit 222 molecular symmetry. Its subunit consists of 498 amino acid residues (Mr 55,880). It has been crystallized at room temperature using polyethylene glycol 1500 as precipitant. The crystals, growing to dimensions of 0.4 mm × 0.4 mm × 1.0 mm within 2 weeks, belong to the tetragonal space group P4₂2₁2 with unit cell dimensions of a = b = 129.63 Å and c = 68.42 Å. The asymmetric unit contains 1 subunit of β-amylase, with a crystal volume per protein mass (V_M) of 2.57 ų/Da and a solvent content of 52% by volume. The three-dimensional structure of the tetrameric β-amylase from sweet potato has been determined by molecular replacement methods using the monomeric structure of soybean enzyme as the starting model. The refined subunit model contains 3,863 nonhydrogen protein atoms (488 amino acid residues) and 319 water oxygen atoms. The current R-value is 20.3% for data in the resolution range of 8–2.3 Å (with 2 σ cut-off) with good stereochemistry. The subunit structure of sweet potato β-amylase (crystallized in the absence of α-cyclodextrin) is very similar to that of soybean β-amylase (complexed with α-cyclodextrin). The root-mean-square (RMS) difference for 487 equivalent Cα atoms of the two β-amylases is 0.96 Å. Each subunit of sweet potato β-amylase is composed of a large (α/β)₈ core domain, a small one made up of three long loops [L3 (residues 91–150), LA (residues 183–258), and L5 (residues 300–327)], and a long C-terminal loop formed by residues 445–493. Conserved Glu 187, believed to play an important role in catalysis, is located at the cleft between the (α/β)₈ barrel core and a small domain made up of three long loops (L3, L4, and L5). Conserved Cys 96, important in the inactivation of enzyme activity by sulfhydryl reagents, is located at the entrance of the (α/β)₈ barrel. © 1995 Wiley-Liss, Inc.     

峨嵋山冷杉森林衰退状况研究

报道和分析了峨嵋山冷杉森林的衰退状况。对冷杉种群的受害程度、分布规律、症状特点及其与海拔、特定生境、立木径级和林型的关系进行了研究分析。指出峨嵋山冷杉森林衰退是全球森林衰退的组成部份,而不是个别的或偶然的现象;肯定了当地冷杉林衰退具有某些个性特征。由此认为,导致当地冷杉衰退的主要原因可能是某种或某些作用范围广、持续时间长、发生频率高、对全球森林系统构成威胁的因素所致。     

Phytophthora spp. from rubbertree plantations in Yunnan Province of China

Phytophthora spp. associated with leaf fall, stem canker and black stripe of rubbertree (Hevea brasiliensis Muell.-Arg.) in Xishuangbanna of Yunnan Province were isolated from leaves, bark, fruit and soil in the plantations. Of a total of 50 isolates, 42 were designated as P. citrophthora (R. E. Sm. & E. H. Sm.) Leonian, while the others were identified as P. palmivora (Butl.) Butl., P. colocasiae Rac. and P. cactorum (Leb. & Conn) Schroet. This appears to be the first report of P. citrophthora on Hevea brasiliensis.     

Frequency analysis of time-varying elastance model of the left ventricle

Zadeh's transfer function method for linear time-variable systems is used to apply frequency-domain analysis to a periodically time-varying elastance model of the left ventricle. Left ventricular pressure computed from the system function of the time-varying elastance and the phasors of aortic flow shows a typical waveform of the measured ventricular pressure.