In vitro stability and protein composition of thick filaments from insect flight muscles

Thick and thin filaments of synchronous and asynchronous insect flight muscles were separated by density gradient centrifugation. A good release of myofilaments from myofibrils was obtained by sonication of myofibrils in relaxing solution with pH 6.1 (locust), pH 6.4 (honeybee) and pH 6.6 (fleshfly), respectively. Thick filaments but not thin filaments were dissolved, if sucrose gradient centrifugation was used to separate the filaments. Thus, sucrose gradients are the medium of choice if actin filaments are to be purified. Glycerol-containing gradients selectively dissolved myosin filaments from fleshfly muscles. The stability of the myosin filaments of all muscles was sufficient in gradients with 10–30% formamide.     

Reevaluation of hydropathy profiles of voltage-gated ionic channels

A reevaluation of the secondary structure of Na, Ca and K channel proteins led to the following results. Only three segments (S1, S5 and S6) of each repeat are sufficiently hydrophobic to be predicted as transmembrane helices, if a window of 19 amino acids is used. Some of the S2 and S3 segments show higher hydrophobic values when calculated with the window of 9 amino acids and can be predicted as short helices. S4 segments are strongly hydrophilic and cannot be predicted as transmembrane helices. Some of the S2, S3 and S4 segments have an amphipathic character; however, these helices do not span a membrane. A model is proposed where 12 hydrophobic transmembrane helices surround 12 shorter helices, forming a hydrophilic pore. In addition, a unique pattern for S4 segments of voltage-gated channel proteins is defined.     

Enzyme immunometric assay for the determination of pregnancy associated plasma protein A (PAPP-A) with the antigen as solid phase (conjoint IEMA)

Summary Purified pregnancy associated plasma protein A (PAPP-A) can be effectively bound to polystyrene microtitre plates. This immobilized antigen competes with the added serum PAPP-A of unknown concentration for the limited amount of peroxidase-labeled monospecific anti-PAPP-A antibody incubated simultaneously. The sensitivity is 0.2 WHO unit/ml and non-specific binding is 1.0%.Acknowledgments. My thanks go to the Janggen-Pöhn-Stiftung, St. Gallen, Switzerland, for the reception of a fellowship grant which enabled this work to be carried out. I would also like to thank Arnold Klopper, Professor of Reproductive Endocrinology, for many stimulating discussions, Garry Luke for excellent technical assistance, and the Department of Medical Illustration of the University of Aberdeen for the preparation of the graphics. The donkey serum was generously supplied by the Scottish Antibody Production Unit, Carluke, Lanarkshire.     

Heat shock enhances thermotolerance of infective juvenile insect-parasitic nematodesHeterorhabditis bacteriophora (Rhabditida: Heterorhabditidae)

Insect-parasitic nematodes possess many of the attributes of ideal biological control agents, but intolerance to extreme temperatures can restrict their use. We examined whether heat-shock treatments could improve nematode survival and infectivity at temperatures that normally inhibit their activity (35 and 40°C). Nematodes exposed to a sub-lethal temperature (35°C) for 3 h with a latency period of 1–2 h at 25°C killed insects at 35 and 40°C. Correlative evidence was obtained between increased thermotolerance and the synthesis of 70-kDa heat-shock proteins (hsps). These results provide the first evidence of hsp synthesis in the development of thermotolerance and biological activity in the non-feeding, developmentally arrested, infective juvenile nematodes.     

原生动物四膜虫(TetrahymenaS1)高迁移率非组蛋白的研究

利用原生动物四膜虫(Tetrahymena shanghaiensis S1)作材料,经高氯酸抽提,丙酮沉淀等方法,制备取得高迁移率的非组蛋白。在高分辨率的乙酸一脲电泳图谱上,具有小牛胸腺所具有的典型的全部蛋白带。此外还含有一些未经检测的蛋白带。作者认为这些多余蛋白带可能是四膜虫所特有的高迁移率的非组蛋白。     

棉花抗热性与高温诱导可溶性蛋白质关系

为鉴定早期棉花基因型抗热性提供生理指标,选用抗虫棉品种DP,彩色棉品种LV和ZH,研究了棉花萌动期、子叶期、1叶期和自然高温期热激处理与对照可溶性蛋白含量的差异.结果表明:萌动期、子叶期、1叶期热激和自然高温期,DP可溶性蛋白质总含量分别比对照提高10.24%、13.11%、15.09%和74.36%;LV分别比对照提高4.27%、8.47%、16.48%和53.49%;ZH分别比对照提高15.83%、11.22%、17.86%和18.18%.     

耐海水芦荟粗多糖中游离蛋白的去除

分别对Sevag法和酶法去除耐海水芦荟粗多糖中游离蛋白质的条件进行了优化,并比较研究了Sevag法、酶法、三氯乙酸法(TCA法)和盐酸法去除蛋白的效果.结果表明,Sevag法除耐海水芦荟粗多糖中游离蛋白质的最佳条件是V氯仿∶V正丁醇为3∶1,振摇时间为5 min,水相与有机相之比为3∶1;使用蛋白酶K去除耐海水芦荟粗多糖液中的蛋白质时,最佳酶用量为4.5 U/mg.采用Sevag法去除粗多糖中蛋白质效果最佳,且操作简便,多糖损失量少.     

日本沼虾表皮蛋白基因的克隆及表皮组织差异性表达分析

为探究日本沼虾表皮蛋白(Macrobrachium nipponense cuticle proteins,MnCPs)表达模式与表皮组织差异的关系,根据日本沼虾表皮组织转录组测序结果,从头胸甲中克隆到1个含几丁质结合-4(chitin_bind_4)结构域的表皮蛋白(cuticle proteins,CPs)基因,命名为MnCP-2,经BLAST检索,MnCP-2与远海梭子蟹(Portunus pelagicus,ABM54465.1)有50%的相似性.以健康幼虾(体长3.0~4.0cm)的头胸甲、尾扇、游泳足和步足4种厚度存在差异的表皮组织为材料,分别提取C期、D_(0-2)期、D_(3-4)期和A期的RNA,采用Real-time PCR技术,分析了MnCP-2在蜕皮周期不同阶段的相对表达量.结果显示,MnCP-2在头胸甲、尾扇和游泳足中表达水平的峰值出现在D_(3-4)期,而在步足中则出现在D_(0-2)期.提示MnCP-2编码的蛋白可能在新外表皮的形成中发挥重要作用,它在表皮组织不同部位的差异性表达可能是导致表皮结构差异的原因之一.     

水稻幼苗叶片应答稻瘟病侵染的差异蛋白谱分析

为了探讨水稻感病基因型种质响应稻瘟病侵染的蛋白质表达谱的变化规律和作用途径,以水稻感稻瘟病种质日本晴为材料,采用接种稻瘟病菌分生抱子悬浮液,24,48和72 h后提取叶片蛋白质,采用i TRAQ蛋白质组学技术研究稻瘟病胁迫下水稻叶片蛋白质组的变化.结果表明,稻瘟病侵染诱导了水稻幼苗叶片内涉及氧化还原平衡、防御、信号传导、糖和能量代谢、氨基酸代谢、光合作用,以及蛋白质代谢等代谢途径相关的53个蛋白质的表达量发生了改变.GO分析表明稻瘟病主要调控了植株体内细胞内平衡、代谢过程和蛋白质代谢等生物学过程.稻瘟病侵染激活了活性氧代谢、防御,以及热休克蛋白等相关的途径,而抑制了蛋白质生物合成过程.结合这些差异表达蛋白的丰度变化结合它们可能的功能,描绘了水稻应答稻瘟病侵染的蛋白质代谢网络,有助于在蛋白质水平上了解其应答过程.