Influence of phytoplankton on the response of bacterioplankton growth to nutrient enrichment

1. Laboratory experiments were conducted to test the effect of nutrient enrichment on bacterioplankton growth in the presence and absence of phytoplankton. 2. In one series of experiments, bacterioplankton growth in terms of specific activity [³H-thymidine incorporation (cell number)^?1] was greater in whole lake water samples than in samples from which phytoplankton had been removed by filtration (1.0 μm), regardless of the nutrient enrichments (control, NH⁺₄ plus PO^3-₄ and mannitol). Organic C enhanced bacterioplankton growth in both whole and filtered lake water. 3. In another series of experiments (with the same nutrient enrichments as in the first experiment except that glucose replaced mannitol), bacterioplankton growth in whole lake water enriched with PO^3-₄ plus NH⁺₄ and incubated in the light was greater than in two treatments designed to inhibit photosynthetic activity (+DCMU and dark). Bacterioplankton response to nutrient addition was greatest in the PO^3-₄ plus NH⁺₄ enrichment under all three conditions (light +DCMU, and dark). 4. These results indicate that bacterioplankton growth could be directly limited by inorganic P and N when these elements are in short supply. Enhancement of bacterioplankton growth by phytoplankton occurs only under PO^3-₄ and NH⁺₄ replete environments.     

白细胞介素对大鼠海马培养神经元膜电特性的影响

用细胞内微电极记录方法研究了重组人白细胞介素－１β（ｒｈＩＬ－１β）和重组人白细胞介素－２（ｒｈｉＬ－２）对分散培养的新生大鼠海马神经元膜电性质的影响。采用压力脉冲微量给药技术将白介素施加于所记录的细胞表面。结果发现：１００Ｕ／ｍｌ浓度的ｒｈＩＬ－１β使受作用的海马神经元超极化４．２０±１．８６ｍＶ;１００Ｕ／ｍｌ浓度的ｒｈＩＬ－２使５０％受作用的海马神经元去极化１１．１２±３．７１ｍＶ,并伴有强烈的自发放电反应,而１０００Ｕ／ｍｌ浓度的ｒｈＩＬ－２使１００％受作用的神经元超极化３．２５±０．６３ｍＶ,这些神经元的膜阻抗均无明显变化。本实验结果提示ｒｈＩＬ－１β和ｒｈＩＬ－２可显著影响体外培养海马神经元的膜兴奋性。     

体内体外培养下飞蝗雄性生殖细胞的分化

在单一TCl99或GRACE培养液中培养的四龄三天东亚飞蝗(Locusta mtgratoria mani lensis精小管,其精子发生只发育至初级精母细胞期,培养液中添加10%小牛血清或飞蝗精巢匀浆液可促使其发育至次级精母细胞期,添加10%分别取自东亚飞蝗蝗蝻、柞蚕蛹及蓖麻蚕蛹的血淋巴可促进其产生约20%的精子。 蜕皮激素及保幼激素对精子的产生无显著影响。移植培养的精小管在受体飞蝗体内不能发育产生精子,注射20μg/虫蜕皮激素可促使其产生大量精子。完整精巢无需注射蜕皮激素即可在受体飞蝗体内发育产生精子。结果表明,昆虫血淋巴内可能含有促细胞分化类因子,此(类)因子可能无种属特异性,外源蜕皮激素可能对精子发生无直接作用,但精子发生同时需要蜕皮激素和血淋巴因子,精巢本身可能有自己的蜕皮激素来源。     

大阪鲫鱼（Carassius Auratus cuvieri Temminck et．Schlegel）雌性特异血清蛋白生化特性及免疫细胞化学定位的研究

雌性特异血清蛋白存在于成熟雌性大阪鲫鱼血清中,雄鱼则无。注射雌二醇可诱导雄鱼及成熟雌鱼合成这种蛋白质并引起鱼肝细胞粗面内质网增加,糖元颗粒减少。从诱导的大阪鲫鱼血清中分离出电泳纯的雌性特异血清蛋白的分子量为４６６０００±４０００（ｎ＝１０）,电泳谱带有３条,用纯的雌性特异血海蛋白制备的兔抗鱼抗血清不与雄鱼血清发生免疫反应,而与正常成熟雌鱼及诱导鱼的血清形成１条免疫沉淀线。免疫细胞化学定位诱导及成熟雌鱼的肝细胞核外细胞质有阳性颗粒,在卵母细胞外围有成团的阳性颗粒分布。     

牛生长激素释放因子的融合表达及其产物的化学加工

通过寡核苷酸引导的定位突变,在人工全合成的第２７位为Ｉｌｅ的牛生长激素释放因子［Ｉｌｅ２７］ｂＧＲＦ（１－４４）ＯＨ基因的５＇端ＡＴＧ后插入Ｔｒｐ密码子序列,并分别了构建了Ｐｌ ｐｒｏｍｏｔｅｒ控制下、以β－半乳糖苷酶和ｐｒｏｔｅｉｎ Ａ结合ＩｇＧ ｄｏｍａｉｎＢ、Ｃ为载体蛋白的融合型基因表达质粒ｐＢＬＥ３１０和ｐＢＬＰＡＥ２Ｄ,在大肠杆菌中得到高效表达。经ＳＤＳ－ＰＡＧＥ分析,表达产物β－Ｇａｌ     

蚕豆（Vicia faba L．）叶肉细胞中ABA的胶体金免疫电镜定位

利用胶体金免疫电镜定位技术对蚕豆叶肉细胞中ＡＢＡ定位的研究表明,在以ＡＢＡ抗体处理的切片中,叶绿体有大量的金颗粒标记,细胞质和细胞核也有金颗粒标记,但液泡和细胞壁中没有金颗粒标记。免疫染色前用胰蛋白酶处理可显著增强金颗粒标记密度,而不用ＥＤＣ固定或以免疫前兔血清处理的切片中几乎没有金颗粒标记。本实验为蚕豆叶肉细胞中ＡＢＡ的分布提供了直接的证据并说明了该技术是研究ＡＢＡ定位的一种可靠的方法。     

A Novel Experimental System for Studies of Photosynthate Transfer in the Developing Wheat Grain

The aim of this study was to develop a valid and convenientexperimental system for exploring photosynthate transfer inthe developing wheat grain. Structural characteristics relatingto photosynthate transfer and the composition of the endospermcavity sap were examined during the linear stage of grain developmentat 25±3 d after anthesis. Based on the results of thesestudies, an experimental system was devised to permit the directmonitoring and manipulation of photosynthate transfer from theendosperm cavity to the storage endosperm. A novel approachwas used whereby insertions were made into the endosperm cavityby a needle at the embryo end and a piece of microcapillarytubing at the stigma end of the detached grain. By this means,the experimental solution was delivered into and flowed longitudinallyunder gravity through the endosperm cavity to exit at the stigmaend. The composition of the experimental solution reflected the principalsolute concentrations and osmolality of the in vivo endospermcavity contents. With the introduction of the solution intothe cavity, it was found that the viability of grain tissueswas maintained for up to 30 h. During a 24 h period both therate of sucrose uptake and subsequent incorporation into ethanolinsolublecomponents were shown to reproduce the rate of starch biosynthesisand in vivo grain growth. Moreover, the experimental systemeffectively reproduced the in vivo pathway of photosynthatetransfer from the endosperm cavity via the modified aleuronecells into the endosperm. As a result, this system providesa new approach to study photosynthate transfer in the developingwheat grain. Key words: Wheat grain, endosperm cavity, experimental system, photosynthate transport     

蛋白质双向电泳、印迹转移及蛋白质合成无细胞体系技术在小鼠腹水细胞EF-3研究中的应用

本文应用近年发展起来的生化技术――蛋白质双向电泳（其第一向为等电聚焦,第二向为SDS凝胶电泳）,将小鼠腹水细胞核糖体蛋进行了指纹分离。并利用蛋白质印迹转移（Western blotting）,将转移后的硝酸纤维膜与交联了碱性磷酸酶的第二抗体和抗酵母EF-3抗体反应,证实该核糖体蛋白含有EF-3同源片段,进而制备了蛋白质合成无细胞体系。通过测定PolyU指导下3 H-phe掺入活力的免疫失活实验,初步证实此同源片段是小鼠腹水细胞蛋白质合成所必需。 The ribosomal proteins of H22a cell,were separated with the method of two-D gel electrophoresis (the first dimention is isoelectric focus and the second is SDS PAGE).Then the Western blotting was used,the transferred nitrocellulose sheet was treated with antiyeast EF-3 antibody and the second antibody bonded with alklinephosphoesterase.The result shows that the ribosomal proteins have a homologous fragment to yeast EF-3 factor.The cell-free system of protein synthesis was also established.By determing the activity of polyU direeted 3H-phe intervention in immunodeactivitive experiment,it is primaril confirmed that this fragment is the esscntial for the protein biosynthesis in H22a cell.     

湖羊瘤胃微生物GH9家族葡聚糖酶基因IDSGLUC9-25的表达与功能表征

【目的】葡聚糖酶是饲用添加剂的重要成分,本研究旨在从湖羊消化道微生物中挖掘性质优良的GH9家族葡聚糖酶基因,用于研发新型饲用酶制剂。【方法】从湖羊瘤胃微生物cDNA中扩增IDSGLUC9-25基因,在大肠杆菌中进行异源表达,对重组蛋白进行诱导表达和纯化,研究重组蛋白的酶学性质和底物水解模式。【结果】IDSGLUC9-25基因编码527个氨基酸,包含一个CelD_N结构和一个GH9家族催化结构域;重组蛋白rIDSGLUC9-25分子量约为62.7 kDa,最适反应温度和pH分别为40℃和6.0,在30-50℃下活性较高,在pH 4.0-8.0范围内能够保持较高的稳定性,经pH 4.0-8.0缓冲液处理1 h后残余活性均大于90%;底物谱分析表明,rIDSGLUC9-25能催化大麦β-葡聚糖、苔藓地衣多糖、魔芋胶和木葡聚糖,比活性分别为(443.55±24.48)、(65.56±5.98)、(122.37±2.85)和(159.16±7.73) U/mg;利用薄层色谱法(thin layer chromatography, TLC)和高效液相色谱法(high performance liquid chromatography, HPLC)分析水解产物发现,rIDSGLUC9-25降解大麦葡聚糖主要生成纤维三糖(占总还原糖64.19%±1.19%)和纤维四糖(占总还原糖26.24%±0.12%),催化地衣多糖主要生成纤维三糖(占总还原糖78.46%±0.89%)。【结论】本研究报道了一种来自密螺旋体属细菌的内切β-1,4-葡聚糖酶IDSGLUC9-25 (EC 3.2.1.4),能高效催化多糖底物生成纤维三糖和纤维四糖,为研发饲用酶制剂和制备低聚寡糖建立基础。     

基于差异基因表达谱的Microbacterium sp. XT11降解黄原胶潜能挖掘

为挖掘微杆菌(Microbacterium sp.)XT11在黄原胶降解过程中起关键作用的功能基因,预测黄原胶降解通路,利用转录组测序技术对该菌株在不同碳源培养条件下的转录本进行测序,对差异基因进行功能富集分析。结果表明,菌株XT11以葡萄糖为对照组,以黄原胶为碳源时可获得上调差异基因213个。显著上调的基因主要富集在聚糖降解、淀粉和蔗糖代谢途径、ABC转运、苯丙氨酸代谢、丙酮酸代谢五个KEGG途径。碳水化合物活性酶(Carbohydrate-active enzymes, CAZymes)功能注释表明,位于同一基因簇上的4个CAZymes基因和黄原胶降解直接相关,其余的CAZymes基因具有潜在的黄原胶降解活性。此外,预测到磷酸转移酶系统(phosphotransferase system, PTS)和ABC转运途径(ABC transporters)参与了胞外黄原胶降解中间产物的跨膜转运。挖掘了菌株XT11中黄原胶降解过程中的功能基因,并阐述了菌株XT11的黄原胶降解通路。