共查询到19条相似文献,搜索用时 156 毫秒
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家蚕抑前胸腺肽类似物的活性鉴定和结构分析 总被引:2,自引:1,他引:1
以家蚕Bombyx mori抑前胸腺肽的氨基酸序列作为基础,通过氨基酸残基的添加、减少和置换,人工合成了一组与家蚕抑前胸腺肽结构类似的多肽。利用家蚕前胸腺体外培养技术,结合蜕皮激素放射免疫分析方法,鉴定了与抑前胸腺肽结构类似的多肽的生理活性,并对它们的活性特征、化学参数、结构和功能、信号传导途径进行了综合的比较和分析。类似物899808的生物学功能与抑前胸腺肽的相同而且活性近似;类似物899805和899809对家蚕前胸腺蜕皮激素的生物合成表现出随浓度增加而增加的促进作用,而低浓度下几乎不促进;899803、899804、899806和899807类似物对家蚕前胸腺蜕皮激素的生物合成的促进和抑制作用与它们的浓度有着依赖关系。实验结果表明,对抑前胸腺肽的氨基酸序列作任何改变,都导致其生理活性的下降、丧失甚至相反的活性。 相似文献
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蜕皮激素是对节肢动物体内类固醇激素的统称,昆虫的蜕皮激素主要由内分泌器官前胸腺合成,具有诱发幼虫周期性蜕皮以及最终变态蜕皮的生理功能。近期的研究工作阐明了前胸腺中原先被称为"黑箱"的一系列酶促反应步骤,此外促前胸腺激素受体的成功鉴定使人们对PTTH信号转导通路调控前胸腺蜕皮激素合成有了更深入的理解。 相似文献
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蜕皮激素是对节肢动物体内类固醇激素的统称,昆虫的蜕皮激素主要由内分泌器官前胸腺合成,具有诱发幼虫周期性蜕皮以及最终变态蜕皮的生理功能.近期的研究工作阐明了前胸腺中原先被称为“黑箱”的一系列酶促反应步骤,此外促前胸腺激素受体的成功鉴定使人们对PTTH信号转导通路调控前胸腺蜕皮激素合成有了更深入的理解. 相似文献
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一、蜕皮激素概况昆虫和甲壳动物蜕皮激素的研究是本世纪四十年代开始的。当时日本学者福田等人曾对家蚕进行结扎、断头及器官移植等试验,发现蚕的前胸腺的分泌活动与蜕皮及变态有着内在的密切联系。1954-1956年,德国卡尔森等从蚕蛹中分离到微量天然蜕皮激素(50mg/1000kg),仅使用0.0075μg就可以使结扎的丽蝇腹部化蛹。1965年,由美国霍夫迈斯特等鉴定了α-蜕皮激素的化学结构,证明它是一种广泛存在于昆虫及甲壳类动物体内的甾族化合物(即类固醇)。后 相似文献
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昆虫成虫蜕皮激素研究进展 总被引:3,自引:0,他引:3
绝大多数成体昆虫羽化后,幼虫期间负责蜕皮激素合成的前胸腺即发生退化,但在一些内部生理及外部环境因子的调控下,某些成体组织(如生殖腺)可扮演类似前胸腺的角色合成与分泌蜕皮激素。蜕皮激素的功能发挥是经受体介导的,包括核受体(如EcR/USP)和膜受体(如DopEcR),它们广泛表达于成体许多组织,参与成虫行为、生殖、寿命、滞育及免疫应答等众多方面的调节,对维持基本的生理功能具有重要作用。就成虫蜕皮激素的产生组织及影响其滴度的因素、成虫蜕皮激素受体概述与组织分布、成虫蜕皮激素信号通路的功能发挥等研究进展方面加以综述。 相似文献
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蜕皮激素及其对蟹虾养殖的影响房凯(四川绵阳师专生物系)(一)蜕应激素概况昆虫和甲壳动物蜕皮激素的研究是本世纪40年代开始的。当时日本学者福田等人曾对家蚕进行结扎、断头及器官移植等试验,发现蚕的前胸腺的分泌活动与蜕皮及变态有着内在的密切联系。1954~... 相似文献
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昆虫促前胸腺激素研究进展 总被引:4,自引:0,他引:4
昆虫促前胸腺激素研究进展李毅平龚和(中国科学院动物研究所,北京100080)关键词促前胸腺激素受体信号系统促前胸腺激素(prothoracicotropichor-monePTTH)因其促进前胸腺(PG)合成和分泌蜕皮激素而得名,以前也称为脑激素,因... 相似文献
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松墨天牛Monochamus alternatus Hope是传播松材线虫Bursaphelenchus xylophilus Nickle的主要媒介昆虫,在其化学防治中经常使用有机磷杀虫剂,而这类杀虫剂有些可通过作用于神经毒性酯酶(neurotoxic esterase, NTE)使敏感的脊椎动物产生迟发性神经毒性。为了深入理解有机磷杀虫剂对害虫毒杀作用机理,增强对昆虫体内NTE活性的了解,我们在松墨天牛中开展了相关的研究。通过差异测定法和经典的乙酰胆碱酯酶(acetylcholinesterase, AChE)活性测定方法,分别测定了松墨天牛幼虫体内NTE和AChE的活性。结果发现,在松墨天牛体内存在NTE活性,其头部的NTE活力为2.80±0.30 nmol·min-1·mg-1,比脂肪体高出了近10倍,但仍较鸟类等脊椎动物为低。体内实验显示,松墨天牛体内NTE可被甲胺磷所抑制; 但在体外实验条件下,甲胺磷对来自松墨天牛头部的NTE活性并没有产生明显抑制作用,而此浓度下的甲胺磷对AChE表现出较高水平的抑制作用。表明松墨天牛体内NTE和AChE对甲胺磷的敏感性完全不同。 相似文献
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Yamanaka N Hua YJ Mizoguchi A Watanabe K Niwa R Tanaka Y Kataoka H 《The Journal of biological chemistry》2005,280(15):14684-14690
The insect brain regulates the activity of the prothoracic glands to secrete ecdysteroids, which affect growth, molting, and metamorphosis. Here we report the identification of a novel prothoracicostatic factor and its receptor in the silkworm Bombyx mori. The prothoracicostatic factor purified from pupal brains of B. mori is a decapeptide with the conserved structure of an insect myosuppressin and thus named Bommo-myosuppressin. Bommo-myosuppressin dose dependently suppressed the cAMP level and inhibited ecdysteroidogenesis in the larval prothoracic glands at much lower concentrations than the prothoracicostatic peptide, the other prothoracicostatic factor reported previously. In vitro analyses using a prothoracic gland incubation method revealed that Bommo-myosuppressin and prothoracicostatic peptide regulate the prothoracic gland activity via different receptors. In situ hybridization and immunohistochemistry revealed the existence of Bommo-myosuppressin in the brain neurosecretory cells projecting to neurohemal organs in which it is stored. We also identified and functionally characterized a specific receptor for Bommo-myosuppressin and showed its high expression in the prothoracic glands. All these results suggest that Bommo-myosuppressin functions as a prothoracicostatic hormone and plays an important role in controlling insect development. 相似文献
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Nitrate Uptake and Reduction of Aseptically Cultivated Spruce Seedlings, Picea abies (L.) Karst 总被引:2,自引:0,他引:2
Spruce (Picea abies (L.) Karst.) seedlings were asepticallycultivated and the effects of different N-nutrition on net uptakeand reduction of nitrate were investigated. The characteristicsof nitrate uptake were calculated, Ks as 0?2 mol m3 andVmax as 18 µmol g1 d1. Low pH, and Al3+ in the medium caused adecrease in nitrate uptake rate. An in vivo assay was set upwhich allowed the measurement of NRA in both roots and needlesof spruce seedlings. The in vivo nitrate reductase activitywas repressed by ammonium and stimulated by nitrate. Nitratereduction was similar to nitrate uptake, negatively affectedby low pH and ammonium. Therefore, a limited N-supply to spruceseemed to occur when pH was low in the rhizosphere combinedwith the presence of Al3+ and . Key words: Spruce, nitrate uptake, nitrate reduction 相似文献
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The essential oil of fruits of Zanthoxylum alatum (Rutaceae)proved repellent to the insect Allacophora foveicollis and fungistaticto 24 fungi, including aflatoxin-produting strains of Aspergillusflavus and A. parasiticus at a minimum dose of 2.0 x 103 µll1.The fungistatic property of the oil was not affected by hightemperature, prolonged storage and increased inoculum. Essential oil, Zanthoxylum, antifungal, insect repellent 相似文献
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Bock C.; Jacob A.; Kirst G. O.; Leibfritz D.; Mayer A. 《Journal of experimental botany》1996,47(2):241-249
The energy status and the phosphate metabolism of Prasiola crispduring and after desiccation stress was investigated by in vivo31P NMR. The effect of desiccation was simulated by additionof the nonionic osmoticum PEG 200 (polyethylene glycol). Photosynthesisand respiration were effectively inhibited under these conditions.The most notable changes in the in vivo 31P NMR spectra werean increase in the cytoplasmic inorganic phosphate signal afterPEG stress, a decrease in the polyphosphates and a lowfieldshift of the core polyphosphate signal followed by an appearanceof extracellular inorganic phosphate. Cytoplasmic pH remainedalmost constant during stress. After a return to control conditions,photosynthesis and respiration recovered within 4 h as wellas the concentrations of the phosphorus metabolites. An as yetunassigned phosphate signal increased in the phosphodiesterregion of the NMR spectra. Simultaneousty, the polyphosphatesignal recovered in intensity and chemical shift. It is suggestedthat phosphate metabolism and complexation of cations to polyphosphatesmay play an important role in the distinct desiccation toleranceof P. crispa. Key words: In vivo 31P NMR, Prasiola crispa, desiccation tolerance, polyphosphates 相似文献
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An Analysis of Seed Development in Pisum sativum: IV. COTYLEDON CELL POPULATIONS IN VIVO AND IN VITRO 总被引:1,自引:0,他引:1
AMBROSE M. J.; WANG T. L.; COOK S. K.; HEDLEY C. L. 《Journal of experimental botany》1987,38(11):1909-1920
A method for quantifying changes in the cell population of Pisumsativum cotyledons during development is described. The methodis based on determining the frequency distribution for cellarea following the random sampling of a single-cell suspensionof cotyledon cells. The population profile of these cells changedprogressively and systematically from a single population, similarin size to meristematic cells, found in embryos less than 3.0mg in fresh weight, to a bimodal population in embryos greaterthan 100 mg fresh weight. This method was used to compare embryosof similar size from two genotypes near-isogenic except forgenes at the r locus. No significant differences were foundbetween the cell population profiles of embryos up to 30 mgfresh weight. However, a significant difference was found betweenembryos with fresh weights of 100 mg, the wrinkled (rr) linehaving a higher mean and maximum cell area (2 951 µm2and 9 240 µm2 respectively) than the round (RR) line (2591µm2and 6470 µm2respectively). Comparisons were alsomade between cotyledon cell populations from round (RR) embryosgrown in vivo and in vitro. The most obvious differences werethe higher mean and maximum cell size of the large cell populationof in vitro grown embryos which were twice those found in vivo.Embryos grown to either 30 mg or 100 mg fresh weight in vitrohad a much greater proportion of large cells in the populationwith a corresponding reduction in total cotyledon cell number,compared with similar sized embryos grown in vivo. These data suggest that comparisons between different genotypes,or, between cultured and in vivoembryos, based on morphologicalsimilarities between embryos, may be invalid and subject tomisinterpretation. Key words: Pea, seed development, cell population 相似文献
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Differential regulation of CD43 glycoforms on CD4+ and CD8+ T lymphocytes in graft-versus-host disease 总被引:2,自引:0,他引:2
Ellies Lesley G.; Jones Amanda Tomlinson; Williams Michael J.; Ziltener Hermann J. 《Glycobiology》1994,4(6):885-893
Two distinct T-cell glycoforms of CD43 result from differentialglycosylation of a single gene product in vivo. The 115 kDaglycoform carries mainly tetrasaccharides and is a pan T-cellmarker, whereas the 130 kDa glycoform carries mainly hexasaccharidesand is associated with T-cell activation. CD43 has been shownto play a role both in enhancing and inhibiting cell adhesion;however, the function of the individual glycoforms is unknown.We have examined the distribution and regulation of the CD43glycoforms in a murine model of acute graft-versus-host disease(GVHD) using monoclonal antibodies (mAbs) S7 and 1B11 specificfor the 115 and 130 kDa CD43 glycoforms, respectively. An increasein T-lymphocyte CD43 130 kDa expression occurred during GVHDfrom day 4 onwards and coincided with splenomegaly and upregulationof the ß1-6GlcNAc transferase (C2GnT), the key enzymeresponsible for the addition of complex O-glycan branching toCD43. When T-lymphocyte subsets were examined for CD43 expression,we found that in GVHD, both CD43 glycoforms were upregulatedon CD4+ T cells. However, in CD8+ T cells, CD43 115 kDa wasdownregulated while CD43 130 kDa was dramatically upregulated,such that two distinct CD8+1B11+ T-cell subsets were observed.These data demonstrate differential expression of the CD43 glycoformsin both resting and activated CD4+ and CD8+ T cells, and suggestthat glycosylation differences between the CD43 glycoforms mayreflect participation in the different functions of these T-cellsubsets in immune disorders in vivo. activation CD43 glycosyltransferases graft-versushost disease T lymphocytes 相似文献
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Time-courses of 14CO2-fixation and of enzyme activities involvedin photorespiration and photosynthesis were determined duringthe life span of cotyledons from sunflower seedlings (Helianthusannuus L.). Glycolate formation in vivo was estimated from theresults of combined labelling and inhibitor experiments. NADPH-glyceraldehyde-3-phosphatedehydrogenase, NADPH-glyoxylate reductase and chlorophyll werewell correlated with the time-course of 14CO2-fixation (photosynthesis).There was, however, a considerable discrepancy between the developmentalsequence of photosynthesis and that of both ribulose-l,5-bisphosphatecarboxylase and glycolate oxidase. Furthermore, time-coursesof glycolate oxidase activity in vitro and of glycolate formationin vivo differed significantly. Therefore, the use of glycolateoxidase as a marker for the activity of photorespiration ingreening sunflower cotyledons may be questionable. Results from14CO2-labelling experiments with cotyledons treated with theglycolate oxidase inhibitor 2-hydroxy butynoic acid suggestthat glycolate formation relative to CO2-fixation is reducedin senescent cotyledons. Key words: Development, glycolate oxidase, photorespiration, ribulose-l,5-bisphosphate carboxylase, oxygenase 相似文献
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Developmental and Biochemical Regulation of 'Constitutive' Nitrate Reductase Activity in Leaves of Nodulating Soybean 总被引:1,自引:0,他引:1
The developmental profile of constitutive nitratereductase activity (cNRA) in leaves of soybean (Glycine max(L.) cv. Bragg) plants at different ages is described. The youngestleaves had most cNRA and the activity dropped off as a newerleaf developed above it. Each leaf had its distinct active periodof in vivo cNRA. This pattern was different in urea-grown andsymbiotically-grown plants (inoculated with Bradyrhizobium japonicumstrain USDA 110), where the latter had no detectable in vivocNRA in older leaves. Urea-grown plants maintained considerablein vivo NRA in such older leaves. When symbiotically-grown plantshad their nodules removed, in vivo cNRA reappeared in olderleaves within 1 d of removal, nearly reaching levels of youngleaves at 3 d after nodule excision. Allantoic acid (ALL), oneof the known transport ureides of soybeans, was implicated asa possible signal molecule from nodules to leaves. Allantoicacid (100 µM) inhibited in vitro c1 NRA significantly,with 400 µM ALL resulting in complete inhibition. In contrast,allantoin (ALN) had no inhibitive effect on NRA. Inhibitionof c1NRA by ALL was by a competitive process, judging from Lineweaver-Burkeplots against nitrate. Kinetics showed a constant Vmax of around105 nmol NO2 mg1 protein h1 and a Km for nitrateof 15 mM, which increased to 60 mM in the presence of 200 µMallantoic acid. Non-specific (ionic and pH-related) influenceswere eliminated. Allantoic acid also had a slight stimulatingeffect of in vitro NRA (up about 25% at 400 µM). Thesefindings suggest that c1NRA may be involved in ureide metabolism,rather than in vivo nitrate metabolism. Key words: Root-shoot interaction, nitrogen metabolism, nodulation, symbiosis 相似文献