取食转Bt基因抗虫玉米后亚洲玉米螟幼虫中肠的组织病理变化

利用透射显微镜（TEM）观察亚洲玉米螟Ostrinia furnacalis (Guenée)幼虫取食了表达Cry1Ab杀虫蛋白的转Bt基因玉米心叶组织后中肠的组织病理变化, 以探讨转Bt基因玉米对亚洲玉米螟的致病机理, 为其合理、安全和持续利用提供理论依据。结果表明：亚洲玉米螟取食Bt玉米后中肠细胞及其细胞器发生了明显的病变。取食Bt玉米12 h后中肠细胞开始病变, 首先微绒毛脱落、内质网开始肿胀, 24 h后内质网肿胀、增多, 杯状细胞杯腔增大, 48 h后微绒毛大量脱落, 细胞开始空泡化, 随着取食时间的增加, 细胞空泡化程度加剧, 在感染前期细胞间的病变程度差异较大。微绒毛脱落、内质网肿胀断裂是在多数取食Bt玉米的亚洲玉米螟中肠细胞发生的普遍病变。由此表明, 人工修饰的Cry1Ab基因导入到玉米染色体组中所表达的杀虫蛋白可使玉米螟幼虫中肠细胞发生病变, 最终导致其死亡。     

取食转Bt基因水稻对稻纵卷叶螟幼虫中肠的组织病理学效应

利用透射电镜观察了稻纵卷叶螟 Cnaphalocrocis medinalis（Guenée）幼虫取食转Bt基因水稻后中肠的组织病理变化。结果表明：稻纵卷叶螟幼虫取食转cry1Ab基因水稻后,中肠上皮细胞的线粒体先发生形态变化,随连续取食时间的延长线粒体出现凝聚、内嵴稀疏、空泡化等,在后期还呈凝聚态随突起脱落或沿杯腔边沿单一排列。内质网的变化也很明显,病变过程中伴随着粗糙内质网的肿胀、核糖体脱落,粗糙内质网增多等现象。细胞核的变化较小,在处理后期出现细胞核拉长、核仁聚集等变化。组织病变程度不一,有的细胞在病变早期就出现了空泡化。     

苦皮藤素V对东方粘虫中肠细胞及其消化酶活性的影响

苦皮藤素V是从杀虫植物苦皮藤Celastrus angulatus Max.根皮中分离的一种对昆虫具有毒杀活性的新化合物。该文通过电镜观察和生化分析研究了其对东方粘虫Mythimnaseparata(walker)幼虫中肠组织及中肠主要消化酶活性的影响。电镜观察发现,中毒试虫的中肠细胞及其细胞器发生明显病变：柱状细胞顶膜微绒毛零乱、减少;线粒体肿胀,出现空白亮区,双层膜不完整;细胞质密度降低,细胞器排列紊乱;内质网池扩张,囊泡化,粗面内质网减少;杯状细胞杯腔变大,微绒毛减少。消化酶活性测定结果表明,中毒试虫中肠的蛋白酶、淀粉酶及脂肪酶的活性和正常虫相比,无显著变化。因此认为,苦皮藤素V主要作用于中肠细胞的质膜及其内膜系统。     

苏芸金杆菌感染粘虫后中肠组织学病变的研究

本文描述了Bacillus thuringiensis HD-1纯晶体感染粘虫Mythimna separata 5龄初幼虫后,其中肠肠壁细胞的超微结构变化.电镜观察表明:首先线粒体,发生病变,随后,细胞顶部肿胀、胞质电子密度下降,顶部胞质之下的各种细胞器均受损伤.随着病变加重,柱状细胞基膜内褶及杯状细胞质突起,这两个富含线粒体的区域发生病变最为明显.最终,肠壁细胞解体从基膜脱落.     

苦皮藤素Ⅴ对东方粘虫肌细胞的影响

苦皮藤素Ⅴ是从杀虫植物苦皮藤Celustrus angulatus Max.根皮中分离的一种对昆虫具毒杀活性的新化合物。采用电子显微镜技术研究了苦皮藤素Ⅴ对东方粘虫Mythimna separata（Walker）肌肉系统的作用。电镜观察发现,苦皮藤素Ⅴ对东方粘虫成虫飞行肌和幼虫体壁肌均具致毒作用,中毒试虫肌细胞特别是肌细胞的质膜及内膜系统发生明显病变：肌膜破坏,脱落;线粒体肿胀,空泡化,崩解;肌原纤维与线粒体间间隙增大;肌质网扩张,产生髓鞘样结构;细胞核肿胀,核质浓缩,核膜破坏;微气管与肌细胞之间间隙增大;肌小节弥散、排列紊乱。这些结果表明,肌细胞质膜及内膜系统可能是苦皮藤素Ⅴ的一个作用部位。     

棉铃虫及粘虫肠中咽侧体静止激素样活性物质对咽侧体活性的影响

利用放射化学的方法分别检测了棉铃虫Helicoverpa armigera、粘虫Mythimna separata幼虫和成虫肠中咽侧体静止激素（allatostatin, AS）样的活性物质。发现在棉铃虫、粘虫幼虫和成虫肠中均存在的AS样活性物质,可以在体外抑制咽侧体（corpora allata, CA）的保幼激素（juvenile hormone, JH）的生物合成。生物测定的结果表明,粘虫幼虫肠中AS样活性物质的含量较棉铃虫的高;粘虫1个幼虫肠当量对CA的JH合成的抑制率达43%,而棉铃虫幼虫肠只有26%。无论是棉铃虫还是粘虫,雌成虫中肠对CA的抑制比雄成虫中肠的高,后肠对CA的JH合成的抑制明显的低于中肠对CA的抑制。中肠对CA的JH合成的抑制是可回复的。中肠粗提物经蛋白酶水解后对CA合成JH的抑制率降低,表明肠中AS样的活性物质是肽或蛋白质。     

取食Cry2Ab蛋白后棉铃虫幼虫中肠组织的病理变化

为了明确Cry2Ab杀虫蛋白的作用机制, 利用透射电镜观察了棉铃虫Helicoverpa armigera (Hübner)3龄末幼虫取食含Cry2Ab蛋白（8 μg/g）饲料后中肠的组织病理变化, 并与分别取食含Cry1Ac蛋白（0.97 μg/g）饲料和正常饲料的棉铃虫进行了比较。结果表明： 棉铃 虫取食Cry2Ab蛋白后中肠细胞及其细胞器均发生了明显的病变, 主要表现为： 中肠杯状细胞的杯腔肿胀或拉长, 部分柱状细胞被杯状细 胞挤压出来, 微绒毛脱落, 细胞核皱缩, 质膜和核膜不清晰, 染色质凝聚, 线粒体拉伸变形, 内质网肿胀断裂; 并且随着取食时间 的延长病变越来越明显。与取食Cry1Ac蛋白的棉铃虫相比, Cry2Ab引起棉铃虫中肠组织发生病变的速度较慢。本研究可为Cry2Ab作为转基 因棉花的重要杀虫蛋白在将来更好地发挥作用提供理论依据。     

棉铃虫幼虫取食Vip3Aa蛋白后的中肠组织病理变化

为了进一步明确Vip3Aa的作用机制, 利用透射电镜观察了棉铃虫4龄幼虫取食含Vip3Aa蛋白饲料后中肠杯状细胞的病理变化, 并比较了其病变与取食含Cry1Ac饲料后棉铃虫组织病变的差异。取食含Vip3Aa饲料后, 棉铃虫幼虫的中肠杯状细胞逐渐发生病变, 主要表现为： 微绒毛肿胀、 脱落; 细胞核核膜界限不清晰, 染色质分布不均匀; 线粒体变形、 数量减少, 内脊不清晰; 内质网杂乱不规则、 数量减少。与取食Cry1Ac的棉铃虫相比, 取食Vip3Aa的棉铃虫中肠杯状细胞发生病变较为缓慢, 在取食12 h后才发现明显病变, 随着取食时间的增加病变越来越明显; 而取食Cry1Ac的棉铃虫2 h后中肠杯状细胞就出现明显病变。本研究可为Vip3Aa作为新毒素策略的重要蛋白在棉铃虫Helicoverpa armigera综合防治中更好地发挥作用提供理论依据。     

三种内寄生蜂寄生对小菜蛾幼虫精子发生的影响

内寄生蜂寄生可能会引起寄主的寄生性去势。对小菜蛾Plutella xylostella与菜蛾啮小蜂Oomyzus sokolowskii Kurdumov (膜翅目： 姬小蜂科)、半闭弯尾姬蜂Diadegma semiclausum Hellén (膜翅目： 姬蜂科)、菜蛾盘绒茧蜂Cotesia plutellae (Kurdj.) (膜翅目： 茧蜂科) 3个寄生体系,利用形态学方法和蛋白质技术,研究了寄生对小菜蛾幼虫精子发生的影响。结果表明：菜蛾啮小蜂寄生对寄主的精子发生过程没有影响。半闭弯尾姬蜂寄生造成寄主精母细胞的细胞核畸形,精细胞的染色质超浓缩并趋向核膜,但能形成少量的精子;半闭弯尾姬蜂寄生会导致寄主精巢总蛋白的含量显著下降。菜蛾盘绒茧蜂寄生对小菜蛾幼虫精子发生的抑制程度最强,被寄生寄主的精母细胞出现肿胀,核膜皱缩,胞质中的线粒体发生病变;精细胞的染色体也出现超浓缩并趋向核膜,大量的精子溶解,无正常的精子形成;其精巢总蛋白含量的下降程度比姬蜂寄生的更为明显,且导致分子量为63.4 kD的主蛋白缺失。     

斑蝥素对小菜蛾体壁组织结构的影响

为探究昆虫天然产物斑蝥素(cantharitin,CTD)对鳞翅目昆虫小菜蛾Plutella xylostella(L.)的触杀机制,利用透射电子显微镜观察了该物质处理小菜蛾4龄幼虫体壁组织结构的变化。斑蝥素亚致死剂量0.15μg/头和半致死剂量0.3μg/头点滴处理试虫前胸背板,中毒试虫反映结果类似。处理12h后中毒试虫虫体发黑,陆续死亡。处理12h后,体壁细胞细胞核固缩并且边极化,线粒体扭曲,内脊模糊出现空泡化,线粒体和粗面内质网数量下降;处理24h后,体壁细胞出现的类似处理12h后的症状,且症状更为明显。结果表明CTD对小菜蛾体壁表皮层组织结构无显著破坏作用,但对体壁细胞有明显的致毒作用。     

The larval midgut of the cassava hornworm (Erinnyis ello)

Summary Columnar cells of the larval midgut of the cassava hornworm, Erinnyis ello, display microvilli with vesicles pinching off from their tips (anterior and middle midgut) or with a large number of double membrane spheres budding along their length (posterior midgut). Basal infoldings in columnar cells occur in a parallel array with many openings to the underlying space (posterior midgut) or are less organized with few openings (anterior and middle midgut). Goblet cells have a cavity, which is formed by invagination of the apical membrane and which occupies most of the cell (anterior and middle midgut) or only its upper part (posterior midgut). The infolded apical membrane shows modified microvilli, which sometimes (posterior midgut) or always (anterior and middle midgut) contain mitochondria. The cytoplasmic side of the membrane of the microvilli that contain mitochondria are studded with small particles. The results suggest that the anterior and middle region of the midgut absorbs water, whereas the posterior region secretes it. This results in a countercurrent flux of fluid, which is responsible for the enzyme recovery from undigested food before it is expelled. Intermediary and final digestion of food probably occur in the columnar cells under the action of plasma membrane-bound and glycocalix-associated enzymes.     

Structural observations on the alimentary canal of Paranthessius anemoniae, a copepod associate of the snakelocks anemone Ammonia sulcata

Light and electron microscopy has shown the alimentary canal of Paranthessius to be composed of clearly defined foregut, midgut and hindgut regions. The spacious foregut is cuticle-lined and separated from the midgut by a valve. The midgut epithelium is composed of columnar cells with an apparent secretary/absorptive rôle, and amoeboid cells thought to engulf material from the lumen. The amoeboid cells have large electron-dense central vacuoles containing carbohydrate-and protein-staining material. These cells appear to be sloughed off into the lumen to form part of a faecal pellet. Apart from their digestive rôle the midgut cells store lipid and it is considered possible that they have an osmoregulatory function. The hindgut epithelium cell type, lacks a cuticular layer and is thought to be mainly concerned with absorption. The alimentary canal is surrounded by strands of longitudinal and circular muscle.     

Lysozyme in the midgut of Manduca sexta during metamorphosis.

Low levels of lysozyme were found in the midgut epithelium of the tobacco hornworm, Manduca sexta, during the early part of the fifth larval stadium. This was observed in control insects as well as in bacterially challenged insects. No lysozyme was detected in the gut contents of either group of insects which were actively eating or in the early stages of metamorphosis. However, high levels of lysozyme activity were detected in homogenates of midgut tissue collected from insects later in the stadium. Immunocytochemical studies demonstrated that lysozyme accumulates in large apical vacuoles in regenerative cells of the midgut during the larval-pupal molt. These cells, initially scattered basally throughout the larval midgut epithelium, multiply and form a continuous cell layer underneath the larval midgut cells. At the larval/pupal ecdysis the larval midgut epithelium is sloughed off and the regenerative cells, now forming the single cell layer of the midgut, release the contents of their vacuoles into the midgut lumen. This release results in high lysozyme activity in the lumen of the pupal midgut and is thought to confer protection from bacterial infection. This is the first indication that the lysozyme gene may be developmentally regulated in a specific tissue in the absence of a bacterial infection.     

Effect of sublethal Bacillus thuringiensis crystal endotoxin treatment on the larval midgut of a moth, Manduca: SEM study

The effect of a single, sublethal dose of B. thuringiensis crystal endotoxin on the midgut of the moth Manduca sexta larvae was monitored during acute and recovery stages. Initially both goblet and columnar cells swelled. Many columnar cells produced membrane extrusions. In some cases the affected cells ruptured, extruding cellular debris into the midgut lumen. Following the acute stage, the midgut tissue recovered, the damaged cells being extruded into the midgut lumen apparently as newly regenerated cells rose to take their place. The insects appeared to recover completely and continue normal development.     

苏云金芽胞杆菌HA和HD对黄曲条跳甲成虫的毒力分析

黄曲条跳甲Phyllotreta striolata (Fabricius)是为害十字花科蔬菜的世界性害虫之一.为了探究苏云金芽胞杆菌HA和HD对黄曲条跳甲成虫的防治潜力,本研究测定了苏云金芽胞杆菌HA和HD菌株对黄曲条跳甲成虫的毒力,以及对其谷胱甘肽-S-转移酶(GST)活性和中肠组织形态的影响.结果 表明:Bt-HA和Bt-HD均对黄曲条跳甲成虫有杀虫活性,LC50分别为4.01×108 CFU/mL和1.17×108 CFU/mL.菌株Bt-HD处理组的GST酶活性高于对照组和菌株Bt-HA处理组.菌株Bt-HA处理黄曲条跳甲成虫14 d后,中肠微绒毛肿胀脱落;菌株Bt-HD处理黄曲条跳甲成虫4d后中肠微绒毛开始疏松脱落,14 d后中肠柱状细胞底膜变形脱落.综上所述,苏云金芽胞杆菌HD对黄曲条跳甲成虫的毒力更强,是防治黄曲条跳甲成虫的优势菌株,其杀虫机理值得深入研究.