Localization of corazonin in the nervous system of the cockroach Periplaneta americana

Antisera raised to the cardioactive peptide corazonin were used to localize immunoreactive cells in the nervous system of the American cockroach. Sera obtained after the seventh booster injection were sufficiently specific to be used for immunocytology. They recognized a subset of 10 lateral neurosecretory cells in the protocerebrum that project to, and arborize and terminate in the ipsilateral corpus cardiacum. They also reacted with bilateral neurons in each of the thoracic and abdominal neuromeres, a single dorsal unpaired median neuron in the suboesophageal ganglion, an interneuron in each optic lobe, and other neurons at the base of the optic lobe, in the tritocerebrum and deutocerebrum. The presence of corazonin in the abdominal neurons and the lateral neurosecretory cells was confirmed by HPLC fractionation of extracts of the abdominal ganglia, brains and retrocerebral complexes, followed by determination of corazonin by ELISA, which revealed in each tissue a single immunoreactive peak co-eluting with corazonin in two different HPLC systems. Antisera obtained after the first three booster injections recognized a large number of neuroendocrine cells and neurons in the brain and the abdominal nerve cord. However, the sera from the two rabbits reacted largely with different cells, indicating that the majority of this immunoreactivity was due to cross-reactivity. These results indicate that the production of highly specific antisera to some neuropeptides may require a considerable number of booster injections.     

Cytoskeleton modifications induced by phenobarbital, 2-acetylaminofluorene and 4-acetylaminofluorene in normal and initiated/selected hepatocytes: Relation with the “resistant” phenotype

Initiatedlselected (ISH) and normal (NH) rat hepatocytes were used to study cytoskeleton modifications induced by three liver acting chemicals: 2-AAF, a liver complete carcinogen; PB, a liver tumor promoter; and 4-AAF, a noncarcinogen analogue of 2-AAF. Cytoskeleton alterations were visualized by disappearance of F-actin fibers and tubulin depolymerization. The three drugs induced actin fragmentation in normal hepatocytes; a net loss of actin protein was observed with PB. They also induced varied tubulin depolymerization. The principal difference between chemicals is that 2-AAF led to non-reversible effects, in comparison with PB and 4-AAF which induced reversible damages on cytoskeleton. By contrast to normal hepatocytes, the cytoskeleton of ISH obtained from rats subjected to the resistant hepatocyte protocol was much less susceptible to the effect of the three chemicals. Moreover, we observed a lack of LDH release in the culture medium and a very rapid inducibility of GST activity after exposure of ISH to drugs. The moderate effect of the three chemicals on actin and tubdin in ISH could thus be explained by the resistant metabolic profile of these cells.Abbreviations TPA 12-O-tetradecanoyl-phorbol-13-acetate - PB phenobarbital - 2-AAF 2-acetylaminofluorene - 4-AAF 4-acetylaminofluorene - GSH reduced glutathione - GST glutathione-S-transferase - LDH lactatedehydrogenase - NH normal hepatocytes - ISH initiated/selected hepatocytes - BSA bovine serum albumin     

Molting fluid enzymes of the tobacco hornworm,Manduca sexta: Timing of proteolytic and chitinolytic activity in relation to pre-ecdysial development

Developmental profiles for a number of molting fluid (MF) enzyme activities were established and related to the progress of pupal cuticle degradation during the four days that precede the eclosion of adult tobacco hornworms. Cuticle degrading activity, molting fluid protease 1 (MFP-1), and molting fluid protease 2 (MFP-2) all increased in activity at the time that loss of material from the old cuticle occurred. In contrast, chitinase and β-acetylglucosaminidase activities did not parallel weight loss from the old cuticle. These results are consistent with the hypothesis that proteolytic activity is a prerequisite for the action of chitinase on cuticle chitin. © 1993 Wiley-Liss, Inc.     

中国转基因大豆的产业化策略

大豆是事关人民生活和经济社会发展的重要农产品之一,提高大豆生产水平和增加自给能力,是中国农业生产必须解决的重大问题。由于中国耕地资源不足的限制,科技创新是提升大豆生产能力的唯一出路。转基因育种是推动大豆生产发展的颠覆性技术,对美国、巴西和阿根廷等世界主产国大豆产业的发展发挥了重要作用。经过20多年的科技创新,中国转基因耐除草剂和抗虫育种技术已经成熟,这些产品的产业化种植可显著降低大豆生产成本和提升单产水平。基于中国转基因大豆技术发展进度和大豆生产的国情特点,我们提出了采用如下策略科学有序推进产业化工作。一是,在产品应用时间上,按照单一耐草甘膦除草剂、多个基因耐草甘膦和草铵膦等多种除草剂,以及耐除草剂与抗虫等复合性状等产品,依次推进相关种子的产业化;二是,在产品区域布局上,按照靶标杂草和害虫的地理分布特点顶层设计各种耐除草剂和抗虫大豆产品的种植区域;三是,在生物安全管理上,研发应用抗性杂草和害虫种群监测与治理技术,延长转基因产品的使用寿命。同时,还要加强野生大豆资源的保护工作,降低转基因大豆基因漂移对野生大豆生物多样性的影响。     

转基因玉米HGK60在不同遗传背景下抗虫性鉴定及农艺性状分析

为研究转基因玉米HGK60在不同遗传背景下遗传稳定性和抗虫效果,利用转Bt cry1Ah基因的转基因玉米HGK60为供体,通过回交转育的方式将cry1Ah基因分别导入玉米自交系郑58、昌7-2、lx05-4、lx03-2,获得转基因玉米自交系HGK60-郑58、HGK60-昌7-2、HGK60-lx03-2、HGK60-lx05-4,并杂交获得HGK60-郑单958（HGK60-郑58 × HGK60-昌7-2）和HGK60-鲁单9066（HGK60-lx05-4 × HGK60-lx03-2）,转化体特异性PCR证明cry1Ah基因已转入不同遗传背景玉米中,ELISA检测不同遗传背景转基因玉米叶片中Cry1Ah蛋白表达情况,结果表明在不同遗传背景玉米自交系和杂交种中Cry1Ah蛋白表达没有显著差异;田间人工接虫和室内玉米螟抗虫性鉴定结果表明,不同遗传背景的转基因玉米高抗玉米螟,室内接虫后4 d幼虫死亡率达到100%;对不同遗传背景转基因玉米HGK60进行农艺性状分析,结果显示与受体对照玉米相比,两者之间农艺性状没有显著差异,转基因玉米HGK60可用于抗虫玉米品种的选育。     

计算机虚拟筛选技术在害虫行为调节剂研究中的应用

害虫行为调节剂是一种以嗅觉系统为靶标的绿色农药,在害虫的田间管理中发挥着重要的作用。然而,其先导化合物的发现通常依赖一系列生物测定的方法,不仅费时费力,且发现效率低。近年来,随着昆虫嗅觉功能数据的积累和结构生物学的飞速发展,以机器学习技术和分子对接为代表的2种基于计算机的药物虚拟筛选方法在害虫行为调节剂的先导化合物研究中发挥着重要的作用,极大地促进了先导化合物的发现效率,减少了筛选的盲目性。本文系统综述了2种虚拟筛选方法及其在害虫行为调节剂先导化合物研究中的应用,并对2种筛选策略在实际应用中存在的问题及应用前景进行了讨论。     

Poleward increase in feeding efficiency of leafminer Stigmella lapponica (Lepidoptera: Nepticulidae) in a latitudinal gradient crossing a boreal forest zone

Damage to plant communities imposed by insect herbivores generally decreases from low to high latitudes. This decrease is routinely attributed to declines in herbivore abundance and/or diversity, whereas latitudinal changes in per capita food consumption remain virtually unknown. Here, we tested the hypothesis that the lifetime food consumption by a herbivore individual decreases from low to high latitudes due to a temperature-driven decrease in metabolic expenses. From 2016 to 2019, we explored latitudinal changes in multiple characteristics of linear (gallery) mines made by larvae of the pygmy moth, Stigmella lapponica, in leaves of downy birch, Betula pubescens. The mined leaves were larger than intact leaves at the southern end of our latitudinal gradient (at 60°N) but smaller than intact leaves at its northern end (at 69°N), suggesting that female oviposition preference changes with latitude. No latitudinal changes were observed in larval size, mine length or area, and in per capita food consumption, but the larval feeding efficiency (quantified as the ratio between larval size and mine size) increased with latitude. Consequently, S. lapponica larvae consumed less foliar biomass at higher latitudes than at lower latitudes to reach the same size. Based on space-for-time substitution, we suggest that climate warming will increase metabolic expenses of insect herbivores with uncertain consequences for plant–herbivore interactions.