家蚕后丝腺细胞的超微结构

本文描述了家蚕幼虫后丝腺细胞的超微结构,并讨论了保幼激素类似物(JH—3)的作用。观察到染色质块移向核内膜及核内物质通过核孔流进细胞质的现象。核仁内布满许多小颗粒体。内腔膨大的颗粒内质网充满着细胞质,它们是丝心蛋白合成和暂时贮留的主要细胞器。丝心蛋白经由高尔基复合体或直接形成丝心蛋白体,它们汇集于细胞顶端,以细胞外排作用,将丝心蛋白放入腺腔。自噬体与溶酶体出现于老熟幼虫后期。 经JH—3处理的幼虫,其后丝腺细胞的超微结构与正常的相近似。     

感染大麦黄花叶病毒(BaYMV)的大麦细胞质内含体及细胞器病变的研究

超薄切片电镜观察表明,在感染大麦黄花叶病毒(BaYMV)的大麦(品种“早熟3号”)叶肉细胞中,液泡周围偶而可看到病毒颗粒束,在发病后期黄化或坏死的叶肉细胞中,可见到散布的病毒颗粒。在所有表现症状的病叶叶肉细胞,表皮细胞和木质部薄壁细胞中均可观察到风轮体、束状体、板状集结体以及膜状体等细胞质内含体,未见 卷简体和细胞核内含体。感病初期细胞中,细胞质丰富,核糖体数量增加,内质网肥大,随着病毒症状发喂,叶绿体、线粒体等细胞器逐渐肿大,外膜破裂直至解体。     

不同温度对油桐尺蠖核型多角体病毒在卵巢细胞系中增殖的影响

本试验用油桐尺蠖核型乡角体病毒(Buzura Suppressaria Nuclear Polyhedro-sis Virus)感染油桐尺蠖卵巢细胞系,分别置于0℃、15℃、20℃、26℃、28℃、30℃、37℃下静止培养,观察细胞病理变化,测定细胞的感染百分率和多角体含量。试验结果表明,不同温度对病毒的感染率及其在细胞中复制有明显的影响。26℃是油桐尺蠖核型多角体病毒感染卵巢细胞并形成多角体的最适培养温度,感染率最高,多角体含量也最多。培养温度过低或过高,多角体都不能在细胞内复制。     

油桐尺蠖核型多角体病毒感染Bs484细胞的增殖与病理研究

用油桐尺蠖核型多角体病毒（ＢｓＮＰＶ）感染Ｂｓ４８４细胞,对感染后病毒增殖的部分性质及细胞病理变化进行了研究。结果表明：１．病毒子代的增殖在感染后的不同时间具有不同的变化形式,且增殖量与感染剂量具有一定程度的相关,２．病毒感染细胞后１２小时开始在培养物上清检测到明显的胞外病毒粒子;３．就ＢｓＮＰＶ的增殖而言,２４～２６℃是其最佳发育温度;４．病毒感染细胞后的明显病变特征是核内充满多用体,细胞堆积以及细胞体积膨大,同时观察到二类感染细胞,一种核内含较多的多角体,另一种核内则只有几个多用体。     

甜菜无融合生殖单体附加系M14 成熟胚囊的超微结构特征

以甜菜无融合生殖单体附加系M14(Beta vulgaris, 2n=18+1)为实验材料, 利用电子显微镜技术对成熟胚囊及其超微结构进行研究。结果表明: M14成熟胚囊包括1个卵细胞、2个退化的助细胞、1个具有次生核的中央细胞和3-6个反足细胞。其卵细胞具有3种不同的形态: (1)极性正常的卵细胞, 细胞核位于合点端, 细胞质含有大量核糖体、线粒体、内质网等细胞器; (2)细胞核位于细胞中央; (3)细胞核位于珠孔端, 且后2种形态细胞器的种类与数量少。大多数胚囊中的2个助细胞在开花前已退化。中央细胞的次生核位于反足细胞附近; 未经受精自发分裂前的卵细胞与中央细胞的细胞核大、核仁明显, 细胞器的种类与数量多, 呈现旺盛代谢活动特征, 成为二倍体孢子无融合生殖过程中, 卵细胞与次生核自发分裂的细胞学标志。     

花椒珠心胚的超微结构及珠心细胞ATP酶的细胞化学定位

应用透射电镜对花椒（Xanthoxylum bungeanum Maxim)珠心胚原始细胞,多细胞原胚和此时期的珠心细胞及其ATP酶的分布进行了详细的观察,珠心胚原努细胞具厚的细胞壁,明显分为电子致密的外层和电子透明的内层,无胞间连丝,大的核中未见核仁,细胞质富含细胞器,多细胞原胚的壁比原始细胞的薄,电子透明,均质,具胞间连丝,核体积增大,核仁1至2个,细胞质中细胞数的数量明显增加,珠孔端的珠心细胞比胚性细胞体积大,细胞液泡化程度高,细胞质稀薄而呈现衰退趋势,ATP酶分布于液泡膜及液泡液中,与胚性细胞相接触的最内层珠心细胞胞质降解,核严重变形,最终细胞解体,此时无ATP酶活性反应。     

油桐尺蠖核型多角体病毒在Bs484细胞中的感染特性研究

本文研究了油桐尺蠖核型多角体病毒(简称BsNPV)在油桐尺蠖成虫卵巢细胞系(Bs484)中的以下感染特性:1.病毒接种传代3-4天的细胞时,病毒感染率最高;2.病毒按种量在一定范围内与感染细胞的多角体总产量平行;3.病毒在细胞中连续传代七次后其滴度无明显变化;4,病毒基因组在感染细胞后6小时左右开始合成,并于感染后14小时达到最大。此外,本实验还发展了一种用于检测感染细胞中的病毒核酸的简便方法。     

大葱卵器及受精后助细胞的超微结构

章丘大葱（Ａllium fistulosum L.cv.Zhangqiu)的卵器由１个卵细胞及２个助细胞组成,观察到不少卵器没有卵细胞,只有２个助细胞。卵细胞的核及大部分细胞质位于细胞的合点端,１个大液泡占据了细胞其他部位。卵细胞含有很多的核糖体及多聚核糖体、嵴明显的线粒体、粗面内质网、高尔基体具小泡,卵细胞似是一个活跃的细胞。细胞外被细胞壁,其合点端及侧方与助细胞共同壁不连续,助细胞有一较大的核,位于细胞膨大的部位,众多的小液泡遍布细胞中。核糖体及聚合核糖体、线粒体,粗面内质网及风心圆环状粗面内质丰富,高尔基体及小泡常见,反映了其活跃的代谢作用。助细胞合点端及侧方与卵细胞、中央细胞的共同壁不连续,与卵细胞共同壁含胞间连丝,壁不连续处,有不状多层膜结构伸入卵细胞质,显示助细胞可能对卵细胞提供营养,伟粉后,一个助细胞退化,宿存助细胞至随胚胚期尚存在,它经历了一个缓慢的退化过程,出现质壁分离,细胞质变稀,液泡扩大,细胞器逐渐减少,在椭形胚期,宿存助细胞核内的染色质及核仁消失,有细胞质侵入核内,因宿存助细胞壁变厚,细胞质出现现脂滴,宿存助细胞可能仍有合成功能,宿存助细胞壁出现若干无壁部位,细胞内的营养物质可能通过无壁部位向胚乳转运,供游离核胚乳及胚乳细胞化初期的发育。     

家蚕CPV感染离体细胞的电镜观察

本文报道了BmCPV感染家蚕细胞系后的电镜观察。病毒感染早期,细胞质内形成电子致密的病毒发生基质,由病毒发生基质形成BmCPV球状病毒粒子;病毒感染48小时后,多角体在病毒发生基质周围形成,大量的病毒粒子随机包埋在多角体内;病毒接种后96小时,多角体数目增多,其形状有三角,四角,五角及六角形,细胞质内充盈多角体致使细胞核被挤向细胞一侧并伴有形态的改变,受染细胞约为40％。     

腰带长体茧蜂毒液器官和卵巢的形态学及其超微结构

应用超薄切片和电镜技术,观察内寄生蜂腰带长体茧蜂Macrocentrus cingulum Brischke毒液器官和卵巢的形态结构。腰带长体茧蜂毒液器官由1个毒囊和2条毒腺组成,毒腺接于毒囊的顶端。毒腺由单层分泌细胞、退化的外胚层细胞和环腔的内膜构成,分泌细胞主要由1个明显的细胞核和1个较大囊状细胞器构成,囊状细胞器的功能是分泌毒液。毒囊由肌肉鞘和扁平细胞层构成,但没有分泌细胞。腰带长体茧蜂卵巢1对,每个卵巢由10条左右卵巢小管组成,与侧输卵管相接处略微膨大形成卵巢萼区。2条侧输卵管在产卵管基部会合形成1条总输卵管与产卵管相接。毒液器官通过毒囊的毒液导管附着在总输卵管上。对寄生蜂毒液器官的生物学、细胞学及在分类进化上的意义进行研究。     

家蚕二分浓核病毒在家蚕细胞中的体外拯救

家蚕二分浓核病毒(Bombyx mori bidensovirus,Bm BDV)是特异性感染家蚕中肠引起慢性浓核病症的致病原,基因组含有2套单链DNA分子(VD1和VD2),复制机制尚不清楚。为了能够在体外拯救出有感染性的病毒粒子,构建了Bm BDV的基因组全长的克隆质粒p MD18T-VD1和p UC-VD2,并通过酶切构建的克隆质粒来获得双链的基因组片段VD1和VD2,利用脂质体包埋的方法,线性化共转染Bm N细胞。提取转染后的Bm N细胞总DNA,经去甲基化处理后,通过PCR检测到病毒基因的复制;提取转染后的Bm N细胞和添食回感的家蚕中肠的总蛋白,分别进行蛋白质印记杂交检测,检测到病毒基因的表达。由此首次表明,该病毒线性化的基因组片段通过共转染Bm N细胞的方法,可以在体外条件下拯救出具有感染性的病毒粒子。     

Selective diminishment of virus-specific translatable mRNA in the densonucleosis virus-infected midgut of the silkworm, Bombyx mori, reared at a supraoptimal temperature

Effect of a supraoptimal temperature on the accumulation of virus-specific translatable mRNAs was examined in the larvae of the silkworm. Bombyx mori, infected with Bombyx densonucleosis virus type 2. The results showed that incubation of infected larvae at 35 degrees C resulted in a rapid and selective decrease in the virus-specific translatable mRNAs which preexisted in the infected midgut. Upon temperature-shift from 35 degrees to 25 degrees C, the virus-specific translatable mRNAs became clearly observed within 12 hr. These results indicate that a supraoptimal temperature restricts the accumulation of virus-specific translatable mRNAs. Both rapid decay and suppressed synthesis might be responsible for the selective restriction of virus-specific translatable mRNA accumulation at a supraoptimal temperature.     

Programmed cell death of the ovarian nurse cells during oogenesis of the silkmoth Bombyx mori

In the present study, we describe the features of programmed cell death of the ovarian nurse cells occurring during vitellogenesis of the silkmoth Bombyx mori. At developmental stage 5, the nurse cells occupy one-half of the follicular volume and obtain a rather spherical shape, while the nurse cell nuclei appear large and elongated, forming impressive projections. At the following stage, stage 6, the nurse cells decrease in size and their shape becomes elliptic. The nuclei remain elongated, being also characterized by large lobes. The lobes of the ramified nurse cell nuclei seem to retain the nucleus in the center of the cell during the dumping of the nurse cell cytoplasm into the growing oocyte. At stage 7, membrane enclosed vacuoles can be easily detected into the nurse cells cytoplasm. Ultrastructural analysis and fluorescent microscopy using mono-dansyl-cadaverine staining of these vacuoles also reveal that they represent autolysosomes. Caspase activity is detected during stage 7, as it is demonstrated by using the Red-VAD-FMK staining reagent. At developmental stages 8 and 9, the nurse cells exhibit chromatin condensation, DNA fragmentation and caspase activity. Finally, during the following stage 10, the nuclear remnants are assembled into apoptotic vesicles, which, after being phagocytosed, are observed in the cytoplasm of adjacent follicle cells. We propose that apoptosis and autophagy operate synergistically during vitellogenesis of B. mori, in order to achieve an efficient and rapid clearance of the degenerated nurse cell cluster.     

一种家蚕类浓核病毒的组织病理学特征

本文从家蚕病蚕中分离到一种家蚕类浓核病毒（BmDNV-Like）,对它的组织病理学研究表明:该病毒首先寄生家蚕中肠柱状细胞,继而引起其细胞核的膨大和破裂;组织原位杂交结果表明该病毒既能在家蚕中肠柱状细胞中增殖,也能在中肠的杯形细胞中增殖,甚至在感染后期能在家蚕幼虫的大部分组织细胞中感染和增殖。     

家蚕核型多角体病毒对小鼠的感染性研究

家蚕核型多角体病毒是一类双链闭合环状DNA病毒 ,该病毒被作为载体应用在家蚕生物表达系统 ;为确定该病毒的安全性 ,观察了该病毒对小鼠瘤细胞以及小鼠的感染性 ,结果显示芽生型家蚕核型多角体病毒在人DC杂交瘤细胞株和HL60细胞中无增殖 ;不同剂量的包埋型家蚕核型多角体病毒经口灌胃给小鼠 ,在小鼠肾、肝病理切片及电镜观察中未见病毒颗粒 ,用免疫组化试验检测小鼠肾、肝组织中的多角体病毒也为阴性。     

转座子介导的多角体基因表达及提高病毒粒子的感染效率

现行的杆状病毒表达外源基因的方法是将外源基因取代病毒中的多角体基因,因而得到的重组杆状病毒感染活体时不能经口感染,只能进行针刺注射,效率低且易引起活体感染其他疾病。将家蚕核型多角体病毒(Bombyx mor inucleopolyhedrovirus,BmNPV)中的多角体基因(polyhedrin,poly)及其启动子片段克隆到转座子载体pigA3GFP中,将其与辅助质粒pHA3PIG利用脂质体介导法导入家蚕细胞中,经过多次筛选获得稳定的转基因家蚕细胞。之后先将BmPAK6(含LacZ)及BmGFP(含GFP)重组病毒分别感染转基因细胞,再将得到的重组病毒经口感染5龄家蚕幼虫。结果显示,重组杆状病毒可以经口感染家蚕幼虫。这些研究表明来自于转基因家蚕细胞的poly基因表达产物可以提高重组杆状病毒经口感染家蚕率,为解决杆状病毒表达系统中重组病毒不能经口感染家蚕幼虫的问题提供新思路。     

Replication of an entomopoxvirus in two lepidopteran cell lines

Pseudaletia separata entomopoxvirus replicated in two lepidopteran cell lines, SIE-MSH-805-F and BM-N. Microscopic examination, and the virus passage tests, of infected cultures indicated that the virus replicated more readily in the former cell line. Virus release by exocytosis occurred in both cell lines. A sequence of virus morphogenesis in the cultured cells was described, based on electron microscopic observations of thin sections. The nucleus of infected cells contained spherical inclusions, and the cytoplasm contained virions, immature virus forms, spheroids, and spindles. A portion of the virions in the cytoplasm was occluded within spheroids, which were often associated with crystallogenic matrix. Virions acquired a coat prior to their occlusion.     

Effect of cytochalasin D on cell morphology and AcMNPV replication in a Spodoptera frugiperda cell line

Cytochalasin D (CD) is a specific inhibitor of actin microfilament elongation and has been used to identify actin-dependent cellular processes. In this study we observed the effects of this inhibitor on Autographa californica M nuclear polyhedrosis virus infected and uninfected IPLB-SF-21 cells by electron microscopy. The cytochalasin D-induced morphological effects detected in uninfected cells included lobulate nuclei, double nuclei, long retraction processes, increased zeiosis, more frequent plasma membrane indentations, increased vacuolation, more numerous coated pits and vesicles, filamentous masses in the cytoplasm, and decreased surface microvilli. Observation of infected cells treated with CD revealed that viral morphogenesis was severely affected. Few normal-appearing nucleocapsids were seen in the nucleus, and none were detected in the cytoplasm. Instead, long capsid-like tubular structures appeared juxtaposed to the inner nuclear membrane. Very infrequently sections of these structures contained electron dense material. The center of the nucleus contained electron-dense, spidery-like structures, presumably viral DNA. Normal virus was not observed to bud from the plasma membrane but electron-lucent, coreless-particles were. By 50 hr postinfection occasional polyhedra appeared, but these contained few or no enveloped virions. The intranuclear fibrous masses normally associated with infection were significantly reduced. These observations suggest that viral morphogenesis, especially nucleocapsid assembly, is an actin-dependent process.     

Isolation of herpes simplex virus-1 by intracellular membranes of BHK tk- cells.

Baby hamster kidney (BHK tk-) cells infected with herpes simplex virus-1 (HSV-1) showed a large number of virus particles isolated in vesicles characterized by the presence or the absence of ribosomes or inside cisternae of the rough endoplasmic reticulum or the nuclear envelope. The isolation of the virions by intracellular membranes appeared shortly after infection of the cells by HSV-1. These structures persisted for longer periods where no morphological alterations in the infected cells were noted as well as at periods where expression of the late viral genes and the presence of empty capsids or DNA-containing new capsids in the nucleoplasm of BHK tk- cells were detected. The results suggest that the presence of virions in membranic formations of the infected cells may be an indication of permanent isolation and subsequent deactivation of the viruses rather than an intermediate stage during their transport from the plasma membrane to the nucleus. The possible mechanisms by which the virions are isolated by the intracellular membranes of BHK tk- cells are discussed.