小地老虎及粘虫幼虫对灭幼脲表现自然耐药力的体壁结构和生化基础

小地老虎Agrotis ypsilon rottem.幼虫对灭幼脲具有一定的自然耐药力。本文以粘虫Mythimna separata(Walker)作为敏感性虫种与之进行比较,实验结果表明,灭幼脲对两种试虫的室内毒力相差4倍左右,引起差异的原因,在体壁结构方面主要在于:(1)小地老虎幼虫的表皮层较粘虫的厚4.2倍左右;(2)上表皮不是匀质结构,依靠少数蜡道与体表沟通;(3)几丁质片层内的孔道数较少,仅及粘虫的1/4。由此构成了表皮对疏水性的灭幼脲表现抗穿透的性能。小地老虎幼虫体壁还含有较强的生化防卫体系,灭幼脲对多功能氧化酶、芳基酰胺酶有明显激活效应,这两种酶都是灭幼脲的降解酶。由此认为,小地老虎幼虫对灭幼脲所表现的自然耐药力,是由体壁的抗穿透性能以及由灭幼脲所激活的适应酶所造成。     

灭幼脲对亚洲玉米螟胚胎气管系统形成的影响

初产下的亚洲玉米螟Ostrinia furnacalis(Guenée)卵,经灭幼脲处理,观察发现:具有抑制几丁质合成性能的灭幼脲对该种害虫的胚胎发育阶段不导致中断,而对气管系统的发生和形成产生严重阻碍.卵内幼虫近孵化时不能开始气管呼吸,生命活动停滞,死于卵壳内.这观察结果可阐明灭幼脲的杀卵机制,并指出更好地应用灭幼脲的途径.     

粘虫(Leucania separata Walker)生殖的研究——Ⅰ. 成虫的一般特性

粘虫生殖腺在蛹期已经发育完成, 但雌蛾卵粒内卵黄尚未沉积, 需要取食糖类作为补充营养后, 才能发育成熟。羽化时雄蛾已具备成熟的精子。取食后能进行交配活动。 成虫寿命一般约15—20天, 羽化后即进行生殖活动。其中产卵期比较长。雌雄蛾均在夜间一定时间内进行飞翔、取食、交配、产卵等活动。在本试验中观察到粘虫一生最大产卵量接近2000粒, 孵化率超过90%以上。雌蛾经人为地与雌蛾完全隔离后, 能产下不受精卵, 产卵量稍低, 卵粒不孵化。 按照粘虫飞翔与生殖关系看来, 粘虫的飞翔活动在性成熟前表现异常激烈。粘虫的飞翔的特征是:(1)由于粘虫羽化后即进入性活动期, 雌蛾需要与雄蛾交配方能进行正常生殖活动, 雄蛾强烈地追逐雌蛾, 因而粘虫在性成熟时有剧烈的飞翔活动。(2)由于内在的生理周期节律的活动以及外激素或其他方法促使异性互相吸引, 所以雌雄蛾同时、同在一起飞翔, 在交配前或产卵前大规模飞翔。(3)由于粘虫各个虫期无滞育现象发生, 粘虫发育所要求温度变化幅度在5—35℃之间, 所以当粘虫在幼期遭受某些不利因子刺激后, 在成虫期往往引起特殊的反应, 促使成虫进行有利于生存的趋避活动, 发生迁飞现象, 以便达到粘虫为本身或后代选择适宜的生境区域。     

粘虫生殖的研究——Ⅲ.生殖系统的发育

根据粘虫生殖系统发育过程中的形态变化来区分雌蛾的日龄,是较为可靠和方便的方法。我们从前蛹期开始,研究粘虫雌雄两性生殖系统发育的形态发生过程,在25℃恒温条件下,粘虫雌雄两性内生殖系统的分化在蛹期第五天基本上完成。而生殖细胞发育成熟的时期则雌雄各不相同,雄性精子在成虫羽化时便已发育完成,雌性卵子必须在成虫羽化取食补充营养后方能发育成熟。我俩将粘虫雌蛾卵巢的发育分为4个时期:即(1)乳白透明期,(2)卵黄沉积期,(3)成熟期,(4)产卵后期。卵巢的发育情况可以作为鉴别雌蛾日龄的标准之一。雄性粘虫的睾丸在蛹期有合并现象,井由于排精体积逐渐缩小。由于羽化后雄蛾的生殖系统外形上无特别明显的变化,所见较难判断它的日龄。最后比较了卵粒的发育成熟与咽侧体活动以及飞翔、交配、产卵等的关系。     

粘虫田间种群的室内饲养研究

【目的】为了解河南省粘虫田间种群的生物学特性。【方法】本文对漯河、洛阳、潢川和原阳的1代或2代粘虫田间种群进行了室内饲养,并对幼虫存活,被寄生情况和繁殖能力等进行了研究。【结果】东方粘虫雌蛾和雄蛾的平均寿命分别为(13.73±4.13)d和(23.04±6.89)d,平均产卵前期和平均产卵历期分别为(6.30±0.33)d和(6.69±2.46)d,单雌平均产卵量为(1631.0±66.83)粒。劳氏粘虫雌蛾和雄蛾的平均寿命分别为(13.17±2.70)d和(13.52±3.62)d,平均产卵前期和平均产卵历期分别为(4.03±0.22)d和(8.28±2.71)d,单雌平均产卵量为(912.9±72.82)粒。潢川地区东方粘虫中线虫的寄生率最高(26.0%),漯河地区2代粘虫寄生蜂的寄生率最高(77.5%)。【结论】河南省内发生危害的粘虫主要为东方粘虫Mythimna separata(Walker)和劳氏粘虫Mythimna loreyi。不同地区不同世代东方粘虫的成虫寿命和产卵量没有显著差异,但幼虫中线虫和寄生蜂的寄生率存在明显差异。东方粘虫和劳氏粘虫在雄蛾寿命,产卵前期和单雌平均产卵量等方面均存在显著差异。     

灭幼脲对小地老虎、粘虫及黄粉(虫甲)幼虫内部器官和组织的作用及毒理

小地老虎[Agrotis ypsilop (Rottemberg)]、粘虫[Mythimna separata(Walker)]及黄粉(虫甲)(Tembrio molitor L.)的幼虫经灭幼脲处理后,含几丁质组分的体壁表皮层、气管壁内膜和中肠围食膜等组织,分泌激素的咽侧体、前胸腺等内分泌腺体,以及代谢器科管脂肪体,都分别出现明显可辨的组织学改变和病理症状,同是地表现一些差异程度并不显著的现象.根据中毒症状和组织学的改变,本文详细分析和讨论了死幼脲处理后对上述两种夜蛾幼虫和一种拟步(虫甲)幼虫的毒理学基础.     

七星瓢虫脂肪体的核酸代谢

脂肪体是七星瓢虫卵黄原蛋白合成的主要场所。本文用微量萤光法和细胞光度法测定成虫期脂肪体核酸含量的变化。结果表明,雌虫在成虫期第5天时,脂肪体的RNA/DNA比值出现高峰,雌虫在第9天产卵,说明当脂肪体合成卵黄原蛋白之前,脂肪体细胞的RNA合成十分活跃,这可促使卵黄原蛋白合成速率加快,几天后雌虫即能产出成熟卵块。雄虫脂舫体的RNA/DNA比值高峰在第7天出现,但其比值只有雌虫的一半。取食代饲料的雌虫,脂肪体RNA/DNA的比值一直较低,直到第24天比值才有所提高,但与正常取食蚜虫的雌虫个体的高峰值相比相差也约一半。这种雌虫一直未能产卵,说明取食代饲料的雌虫不产卵的原因在于脂肪体中核酸代谢的异常。取食代饲料一直未能产卵的雌虫,经用保幼激素类似物ZR-512处理;3天后脂肪体的RNA平均值明显增高。说明ZR-512对瓢虫脂肪体RNA合成有促进作用。     

粘虫(Mythimna separata Walker)选择产卵场所的意义及颜色在定位中的作用

根据粘虫的产卵习性,在田间分别测定了置于活体寄主和干枯植物上的卵块被捕食的概率,结果表明,枯草上面的隐蔽卵块被捕食的概率最低,与雌蛾的产卵习性相符,说明粘虫产卵选择习性有其生物学意义,即有利于躲避天敌。同时,实验结果表明粘虫幼虫的抗饥饿能力要强于甜菜夜蛾,是其对成虫产卵场所长期适应的结果。室内成虫对不同植物的产卵选择与田间相一致,光谱测定结果也表明绿色植物与雌蛾喜欢产卵的植物秸秆的光谱特征和波峰存在显著差异。观测粘虫雌蛾对不同颜色纸张的产卵选择发现,其喜欢在黄褐色纸张上面产卵,产卵量和产卵次数明显高于绿色纸张,而三者的光谱特征存在显著差异。     

补充营养及产卵底物颜色对粘虫生殖的影响

【目的】进一步探明补充营养和产卵底物颜色对粘虫Mythimna separata(Walker)的影响,为粘虫的室内饲养条件提供参考。【方法】选取5%蜂蜜水、10%蜂蜜水、10%葡萄糖溶液、0.2 mol·L~(-1)麦芽糖溶液、5%葡萄糖+5%蜂蜜混合液、5%果糖+5%蜂蜜混合液、5%葡萄糖+5%果糖混合液、糖醋酒液(3白糖:1白醋:4白酒:2水)8种补充营养,红、黄、绿、蓝、紫、白6种颜色塑料包扎绳作为产卵底物,研究粘虫蛾取食不同补充营养产卵前期、产卵期、寿命及在不同产卵底物上的产卵量。【结果】取食5%葡萄糖+5%果糖混合液和0.2 mol·L~(-1)麦芽糖溶液的雌蛾单雌产卵量最多,取食糖醋酒液的雌蛾单雌产卵量最少,极显著低于前者,取食其余5种补充营养的雌蛾单雌产卵量无显著差异;成虫对蓝色底物的选择性最大,除5%蜂蜜水和10%葡萄糖溶液处理外,其余处理蓝色包扎绳上的平均产卵量显著比其他5种颜色包扎绳上的高,对红、白2种颜色底物的选择性最小,对黄、绿、紫3种颜色底物的选择性介于上述两者之间。【结论】在粘虫室内饲养中,选用5%葡萄糖+5%果糖混合液和0.2 mol·L~(-1)麦芽糖溶液作为补充营养及蓝色物质作为产卵底物,更有利于粘虫的繁殖和种群增长。     

寄主植物对亚洲玉米螟生长发育及雄蛾保护酶活性的影响

【目的】为了明确不同寄主植物对亚洲玉米螟Ostrinia furnacalis (Guenée)生长发育、繁殖及雄蛾保护酶活性的影响。【方法】在温度为(25±5)℃、湿度为75%±5%、光照周期为L∶D=16∶8的恒定条件下,研究了7科12种寄主植物对亚洲玉米螟发育历期、蛹期、成虫期、羽化率、雌蛾繁殖力及雄蛾体内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活力的影响。【结果】亚洲玉米螟能够在12种寄主植物上完成生长发育。取食苍耳的幼虫历期较短(17.4 d),蛹期较短(5.9 d);成虫寿命较长(9.0 d),蛹重较大(50.7 mg);取食油菜的幼虫单雌产卵量较大(210粒/雌),取食油菜和油麦菜的幼虫成活率和蛹羽化率较高,均在80.0%以上。幼虫取食不同植物后,雄蛾体内保护酶的活性差异显著,幼虫取食酸模叶蓼后,雄蛾体内SOD活性较高,幼虫取食苍耳后,雄蛾体内POD和CAT活性较高。【结论】不同寄主植物对亚洲玉米螟生长发育、繁殖及雄蛾保护酶活性均有显著影响。取食苍耳和酸模叶蓼有利于亚洲玉米螟的生长发育。玉米螟在不同寄主植物上的生长发育和繁殖与保护酶活性呈现正相关性。亚洲玉米螟在取食不同寄主植物时,能调节自身保护酶的活性,来适应寄主,满足生长发育的需要。     

EFFECTS OF BENZAMIDE ON EMBRYONIC DEVELOPMENT OF THE HOUSEFLY

This paper deals with the effects of benzamide, a chromosomal RNA inhibitor, on embryonic development of the housefly Musca domestica nebulo. Eggs exposed to benzamide immediately after oviposition continued to develop until the blastema stage, but further development was arrested. Formation of cell boundaries and nucleoli failed to occur and the nuclei at the posterior pole did not differentiate into pole cells. This suggests that synthesis of new RNA is needed for development beyond the blastema stage. Treatment of eggs at different stages of development showed that as development progressed embryos became less sensitive to the drug. Introduction of benzamide into eggs during the pre-blastema period caused irreversible arrest of development, whereas, treatment during post-blastema stages resulted in reversible inhibition of development. The cortical cytoplasm thus appears to induce a significant change in the cleavage nuclei, which alters their sensitivity to the drug.     

Effect of Aminopterin and Deoxyribonucleosides on the Cleavage and Embryogenesis of the Sea Urchin, Hemicentrotus pulcherrimus

In the embryos of the sea urchin, Hemicentrotus pulcherrimus , reared with 150 μM aminopterin from the time of fertilization, cessation of the development occurred at the blastula stage, at which the dTTP level became quite low. Another addition of thymidine to the embryo culture containing aminopterin resulted in an elevation of dTTP concentration in the embryos and allowed them to develop normally. Decrease in the dTTP level, resulting from the inhibition of thymidylate synthesis by aminopterin, probably causes a failure of egg cleavage and development. 5-Bromo-2'-deoxyuridine (BUdR) also released the aminopterin-inhibition of egg cleavage and allowed the treated embryos to develop to early gastrulae. Thereafter, the degeneration of archenteron occurred and these embryos became large permanent blastulae. Other deoxyribonucleosides failed to cancel the inhibition by aminopterin of egg cleavage. In the embryos kept with both BUdR and aminopterin, BUdR incorporation into DNA occurred at a similar rate as in thymidine incorporation in the embryos kept with thymidine and aminopterin, and was inhibited by another addition of thymidine. Without aminopterin treatment, BUdR incorporation hardly occurred and the embryos developed normally. BUdR incorporation into DNA in place of thymidine probably occurs in aminopterin-treated embryos, resulting in abnormal development.     

Maternal program of apoptosis activated shortly after midblastula transition by overexpression of S-adenosylmethionine decarboxylase in Xenopus early embryos

When we studied polyamine metabolism in Xenopus embryos, we cloned the cDNA for Xenopus S-adenosylmethionine decarboxylase (SAMDC), which converts SAM (S-adenosylmethionine), the methyl donor, into decarboxylated SAM (dcSAM), the aminopropyl donor, and microinjected its in vitro transcribed mRNA into Xenopus fertilized eggs. We found here that the mRNA injection induces a SAM deficient state in early embryos due to over-function of the overexpressed SAMDC, which in turn induces inhibition of protein synthesis. Such embryos developed quite normally until blastula stage, but stopped development at the early gastrula stage, due to induction of massive cell dissociation and cell autolysis, irrespective of the dosage and stage of the mRNA injection. We found that the dissociated cells were TUNEL-positive, contained fragmented nuclei with ladder-forming DNA, and furthermore, rescued completely by coinjection of Bcl-2 mRNA. Thus, overexpression of SAMDC in Xenopus embryos appeared to switch on apoptotic program, probably via inhibition of protein synthesis. Here, we briefly review our results together with those reported from other laboratories. After discussing the general importance of this newly discovered apoptotic program, we propose that the maternal program of apoptosis serves as a surveillance mechanism to eliminate metabolically severely-damaged cells and functions as a 'fail-safe' mechanism for normal development in Xenopus embryos.     

Back-transfer of late gastrula nuclei of nucleocytoplasmic hybrids

Late gastrula-early neurula endoderm nuclei from nucleocytoplasmic hybrids consisting of Rana pipiens nuclei and Rana palustris cytoplasm were back-transferred into enucleated eggs of Rana pipiens. Approximately half of the normally cleaved back-transfer embryos developed normally. A similar result was obtained with nuclear transfer controls. As expected, the development of the nucleocytoplasmic hybrid donors, at the time the back-transfers were carried out, was clearly abnormal. Consequently, a significant proportion of endoderm nuclei from these embryos undergo no irreversible changes in their developmental capacity even after the nucleocytoplasmic incompatibility between these two amphibian species is expressed.     

Significance of the sulfonylurea receptor (SUR) as the target of diflubenzuron in chitin synthesis inhibition in Drosophila melanogaster and Blattella germanica

Diflubenzuron (DIMILIN) is a powerful insecticidal chemical which has been known for many years to inhibit chitin synthesis in vivo in insects and related arthropod species. However, its action mechanism has remained unresolved partly because of its inaction on any of the enzymes involved in chitin synthesis in vitro. Based on our previous work (Diflubenzuron affects gamma-thioGTP stimulated Ca2+ transport in vitro in intracellular vesicles from the integument of the newly molted American cockroach, Periplaneta americana L. Insect Biochem. Mol. Biol. 24 (1994) 1009) showing that diflubenzuron inhibits Ca2+ uptake by vesicles obtained from the integument of American cockroach, Periplaneta americana (L.), in vitro, we tested the hypothesis that the action site of diflubenzuron is an ABC (ATP binding cassette) transporter, probably a sulfonylurea-sensitive transporter. Glibenclamide, one of the most commonly used sulfonylureas for type II diabetes treatment, was the positive control. When given to immature insects, glibenclamide clearly caused toxicity, with symptoms indicating molting abnormality comparable to diflubenzuron. Its LD50 (0.472 microg/nymph) was approximately 2.8 times the value obtained for diflubenzuron (0.17 microg/nymph, topical) in German cockroach, Blattella germanica (L.). However, in terms of the inhibitory activities on chitin synthesis, in isolated integuments glibenclamide showed an identical potency to diflubenzuron in B. germanica nymphs. A competitive binding assay with [3H]-glibenclamide and unlabeled diflubenzuron clearly established that the latter is capable of competitively displacing the former radioligand. The KD values observed for vesicles prepared from fruit fly larvae, Drosophila melanogaster M., were 44.9 nM for glibenclamide and 65.0 nM for diflubenzuron, respectively. Furthermore, glibenclamide was found to affect Ca2+ uptake by isolated cuticular vesicles from B. germanica in a manner very similar to diflubenzuron. These results support our conclusion that the sulfonylurea receptor (SUR) is the target of diflubenzuron in inhibition of chitin synthesis in these two insect species.     

Stage-specific gene expression in asynchronous tetraploid mouse embryos formed by fusion of blastomeres and fertilized eggs

Asynchronous tetraploid mouse embryos were generated by electrofusion of fertilized eggs with blastomeres from different cleavage stages. The majority of the cytoplasm was always contributed by the egg. The best development was observed when eggs were fused with 2-cell blastomeres. Both genomes became active in fusion embryos (at least the genes for glucose phosphate isomerase did). Stage-specific protein synthesis seemed to be more adjusted to the developmental stage of the egg's than of the blastomere's genome, but at the 2-cell stage both contributed slightly differently to the protein patterns. Also, the time range of the first appearance of the stage-specific embryonic antigen SSEA-1 was wider in fusion embryos than in controls. It seems that the two genomes are not completely synchronized in these tetraploid embryos, a further indication that, in the mouse, the cytoplasm of fertilized eggs might not be compatible with older embryonic nuclei. Some results were presented at the 83. Jahresversammlung der Deutschen Zoologischen Gesellschaft in Frankfurt, 04.-09.06.1990 Correspondence to: U. Petzoldt     

Mécanisme cytologique de la tétraploïdie expérimentale chez le Triton Pleurodeles waltlii

When the eggs of the newt Pleurodeles waltlii, at the beginning of the first furrow formation, are submitted for 10 minutes to a sudden increase in temperature (37.2 to 37.3 degrees C), the subsequently developing embryos are tetraploid. The percentage obtained of viable individuals is about 30% of the number of treated eggs. A temperature between 36.2 and 36.4 degrees C applied at the same period and for the same length of time may lead to viable animals diplo-tetraploid mosaics as previously reported.--Cytological examination showed that at the formation of the first furrow the egg contains two interphase nuclei. During heat treatment, cytoplasmic cleavage regresses resulting in an uncleaved egg with two interphase nuclei. About 2 1/2 hours after heat treatment the egg divides again into two cells. Tetraploidy results from doubling of chromosomes of both nuclei instead of the second mitotic division. The mechanism which leads to tetraploidy consists in inhibition of the movement of the two asters and aberration of spindle formation.--The mosaic animals develop from eggs in which only one of the nuclei became tetraploid while the other one divided normally.     

Insemination of immature sea urchin (Arbacia punctulata) eggs

Nuclei from osmotically opened erythrocytes and erythroblasts were injected into nucleated or enucleated Xenopus laevis eggs. Although the cleavage pattern of the recipient eggs which started to divide was normal in about half of the cases, nuclei from erythrocytes injected into nucleated or enucleated eggs never promoted development beyond the early gastrula stage. In contrast, nuclei from osmotically opened erythroblasts injected into enucleated eggs promoted development to early tadpole stages (stages 29–36). Frequently, injection of osmotically broken erythroblasts injected into nonenucleated eggs gave rise to triploid larvae which all died at roughly the same early tadpole stages (29–36). Surprisingly, development did not proceed to the stage of advanced organogenesis (stages 44–47), which is easily reached by gynogenetic haploids: The presence of the haploid genome derived from the egg pronucleus did not significantly improve the developmental capacity. Embryos obtained by single injection of erythrocyte nuclei into nucleated eggs were unable to pass the gastrula stage. To invalidate the interpretation that the observed arrest in development was related to nuclear damage during injection of the recipient eggs, single unbroken erythrocytes and unbroken erythroblasts were transferred into nucleated and enucleated eggs. No cleavage was observed in both classes of eggs injected with unbroken erythrocytes. In contrast, erythroblasts were found to induce cleavage in the recipient eggs at a frequency of about 11%. To ascertain that the nucleus of unbroken erythroblasts participated in development, the 1-nucleolar marker was used. Diploid embryos with only one nucleolus present were found following injection of unbroken erythroblasts into enucleated eggs from 2nu females. Triploid 2nu embryos were detected following injection of (diploid) 1nu erythroblasts into nonenucleated eggs from 2nu females. The most advanced development stages reached by these embryos did not, however, differ from the best results found in the first class of experiments: Nuclei from erythroblasts injected undamaged into nucleated or enucleated eggs never developed into a normal tadpole. Serial transfer experiments were performed using normally gastrulating embryos which had developed, following the injection of 1nu unbroken erythroblasts into recipient eggs. These donors for serial transfer experiments were checked for the presence of the 1nu marker. In addition they had passed through a normally cleaving eight-cell stage. No improvement in developmental capacity as compared to first transfer experiments could be found.