昆虫翅型分化的表型可塑性机制

翅多型现象在昆虫中广泛存在,是昆虫在飞行扩散和繁殖能力之间权衡的一种策略,对种群的环境适应性进化具有重要的意义。目前在植食性昆虫中研究较多,有关寄生蜂的翅型分化鲜见报道。综述了昆虫翅型分化的表型可塑性机制。遗传因素和环境因素均对昆虫翅的发育产生影响,基因型对翅型的决定具有显著作用,外界环境条件,包括温度、光周期、食物质量、自身密度、外源激素等因素对昆虫翅的发育也产生重要的调节作用,从而产生翅的非遗传多型性现象。此外,天敌的寄生或捕食作用可能会诱导某些昆虫的翅型产生隔代表型变化。对昆虫产生翅多型现象的生态学意义及其在生物进化过程中的作用进行了讨论,并探讨了寄生性昆虫翅型分化机制在生物防治上的可能应用途径。功能基因组学和表观遗传学的进一步发展可望为彻底揭示昆虫翅型分化机制提供新的机遇和技术手段。     

植物病媒昆虫的翅型分化

翅多型现象是昆虫非遗传多型性的一种表现,包括不具飞行能力的短翅型或无翅型,以及可以进行长距离迁飞的长翅型或有翅型。翅多型现象常发生在可以携带病原并将其传播给植物宿主的媒介昆虫中,对植物病害的时空分布与暴发有重要影响。本文从翅型分化的遗传规律、诱导因素、分子机制和伴随翅型分化的其他生理表现4个方面,对植物病原主要传播媒介蚜虫和飞虱的翅型分化研究进行综述和梳理。昆虫翅型分化的诱导因素主要包括温度、湿度和光周期等非生物因素以及虫口密度、宿主营养、病毒等生物因素;而其内在的分子机制大多是通过胰岛素/胰岛素样生长因子信号(IIS)通路、c-Jun氨基末端激酶(c-Jun NH₂-terminal kinase, JNK)信号通路、Wingless和嗅觉受体SaveOrco等调控。翅型分化的同时伴随着生理状态的变化,表现为短翅型具有更强的繁殖能力和长翅型含有更丰富的飞行肌结构成分。目前,昆虫翅型分化的研究尚不够完善,有许多需要解答的问题,如找到胰岛素/胰岛素样生长因子信号通路中真正发挥功能的靶基因,JNK如何调控翅型分化以及虫媒病毒影响媒介昆虫翅型的分子机理。本综述可为控制虫媒病原的传播以及其他昆虫翅多型的研究提供参考。     

沙蟋翅多型性的调控机理

沙蟋Gryllus firmus Zera&Denno成虫的后翅有长翅和短翅2种类型,是翅多型性机理研究的极佳模式昆虫。长翅成虫从第5日龄开始迁飞,而短翅成虫的主要特点是繁殖。除了翅的表型差异外,长翅成虫的飞行肌发达,呈褐色;卵巢幼小,直到飞行停止后(大约在10d以后)才开始发育。而短翅成虫的飞行肌退化并呈乳白色;卵巢在第4日龄就发育成熟,表现为卵巢硕大。对翅多型性机理的深入研究,将有利于了解沙蟋迁飞和扩散的内在机理,为准确地预测预报该虫的发生提供重要的理论和实际依据。文章概述沙蟋翅多型性与外界环境的相互关系,以及体内生化代谢和内分泌激素等的变化对该虫迁飞和生殖的影响和作用,进而探讨翅多型的遗传机制和进化意义等问题。     

昆虫翅多型的分子调控机制研究进展

生物如何适应复杂的环境变化是生物学研究的重要科学问题。其中,昆虫在长期的进化过程中形成了翅多型现象以适应复杂的环境,由此通过调控翅型的转换,对不同的环境条件做出响应,从而优化资源分配以平衡迁移或繁殖的需求,但目前对其分子调控机制仍不十分清楚。本文基于国内外最新研究进展,结合作者自己的研究,系统地综述了昆虫体内参与翅型转换调控的多种途径的研究进展,包括胰岛素信号通路、蜕皮激素信号通路、保幼激素信号通路、JNK信号通路、生物胺信号通路和病毒基因水平转移,指出了未来发展的方向。这些研究成果不仅对于进一步阐明昆虫翅多型的分子机制具有指导意义,也为开发以翅型调控为主要内容的害虫综合治理技术提供参考。     

褐飞虱翅型分化调控机制的研究进展

昆虫翅多型作为生物可塑性发育的典型代表,是昆虫对复杂多变环境适应进化的结果。褐飞虱Nilaparvata lugens是一种典型的翅多型昆虫,若虫可发育成短翅型或长翅型成虫,后者的远距离迁飞特性造成褐飞虱在亚洲稻区大面积为害。20世纪60年代以来,前人针对褐飞虱翅多型的发生机理进行了大量研究,发现种群密度、寄主植物质量、温度和光周期等诸多环境因子以及保幼激素均能够影响翅型比例。近20年来,得益于基因组学、 RNAi和基因编辑等生物技术的发展,褐飞虱翅型分化的分子机制研究取得了突破性进展,发现了褐飞虱翅型分化的开关基因FoxO,沉默或敲除FoxO会导致飞虱发育为长翅型;而胰岛素信号通路能够磷酸化FoxO抑制其进入细胞核,从而参与翅型分化调控;锌指转录因子Zfh1能够以启动子结合的方式调节FoxO的转录,与胰岛素信号通路平行调控翅型分化;另一个锌指转录因子Rotund能够与FoxO互作共同调控褐飞虱翅多型。此外,性别决定基因Transformer-2和c-Jun氨基末端激酶通路等也能够影响翅型分化,表明褐飞虱的翅型分化存在多样化的分子调控机制。鉴于半翅目不同亚目间的翅多型机制均有所不同,对褐飞虱翅型分化机制的解析远不足以阐明半翅目乃至整个昆虫纲的翅多型机制,但其研究成果能够引领未来对昆虫翅多型机制的探索研究,并加深人们对昆虫翅及组织可塑性发育与进化的理解。     

昆虫非遗传多型性研究进展

非遗传多型性是指同一基因型或同一基因组通过外界环境诱导可产生两种或者多种不连续表型的现象。该现象在昆虫中已有报道,如变态、季节性非遗传多型、社会性昆虫的等级制等。昆虫通过非遗传多型性做出应答,通过表型改变来适应环境并利用周围环境物质以达到躲避天敌从而进行生存繁衍的目的。因此,非遗传多型性是昆虫种类繁多、数量庞大的主要因素之一。近几十年来,非遗传多型性日益受到广泛关注,从最初对现象的描述,到诱导该现象产生的可能因素的实验验证,至目前大数据时代下利用二代测序技术、基因敲除和RNA干扰等技术揭示其分子机制。本文对近年来非遗传多型性在昆虫中的研究进展进行了总结,并对未来的趋势进行了展望。     

小翅稻蝗(Oxya yezoensis Shiraki)翅多型现象浅释

对小翅稻蝗翅型构成的季节变化,长翅型、短翅型产卵前期间的差异及光周期对翅型分化的影响进行了调查,结果表明,小翅稻蝗存在着明显的翅多型现象,相对翅长(前翅长/后足腿节长)最长可达1.49,最短只有0.50,翅长呈连续性双模态分布。早期羽化的个体大多为长翅型,随着季节的推移,羽化成虫短翅率逐渐增加。长翅型雌成虫的产卵前期间为42.7±13.1日,短翅型为15.3±6.4日,短翅型雌成虫的产卵前期间显著短于长翅型。不同的光周期短翅成虫出现的比例不同,光照短于LD1212时,几乎全为短翅型,LD1410短翅率为66.8%,LD168则长翅率达62.1%,光照长于LD186时,几乎全为长翅型。     

昆虫后翅形态进化研究获得新进展

<正>昆虫是地球上最繁盛的生物类群,翅的获得在昆虫演化历程中扮演了重要角色。长久以来,后翅特征在昆虫的识别和种类鉴定中就已获得广泛应用且具重要价值。伴随着支序系统学的发展,后翅成为系统发育研究中非常重要的特征来源。但是后翅的形态是否能够反映整个昆虫的系统发育并未获得证实。而且前人对后翅形态进化的     

灰飞虱翅型及翅发育基因对长、短翅定向选择的响应

【目的】稻飞虱翅型调控的分子机理已较为清楚,但是在长、短翅品系不断纯化过程中翅型及翅发育基因表达水平的变化规律还不明确,因此本研究旨在阐明灰飞虱Laodelphax striatellus长、短翅品系的翅长、翅重及翅发育基因对翅型定向选择的响应,以期为明确灰飞虱翅型的遗传进化规律提供参考。【方法】在恒定条件下对灰飞虱长、短翅型分别进行14和13个连续代次的定向选择,建立长翅型和短翅型品系;测定各选择代次中两品系的长翅和短翅率、翅长和翅重;并采用qPCR方法测定翅发育基因InR1,InR2和FoxO的相对表达水平;通过比较长、短翅型品系的翅型指标和基因表达水平在各选择代次间的差异来表征翅型及翅发育基因的选择响应。【结果】长翅型和短翅型分别进行连续14和13代的定向选择,灰飞虱长翅型品系的长翅率以及短翅型品系的短翅率在各选择代次间均显著上升,均已保持在95%左右。随着选择代次的增多,长翅型品系的翅长不断增长,短翅型品系的翅长不断缩短,长、短翅型品系的翅重均呈变轻趋势。长翅型品系3龄若虫的InR1和InR2相对表达水平随选择代次的增多而下降,但FoxO相对表达水平不随选择代次变化;短翅型品系...     

Wing serial homologs and the origin and evolution of the insect wing

The origin and evolution of insect wings has been the subject of extensive debate. The issue has remained controversial largely because of the absence of definitive fossil evidence or direct developmental evidence of homology between wings and a putative wing origin. Recent identification of wing serial homologs (WSHs) has provided researchers with a potential strategy for identifying WSHs in other species. Future comparative developmental analyses between wings and WSHs may clarify the important steps underlying the evolution of insect wings.     

Swift laboratory thermal evolution of wing shape (but not size) in Drosophila subobscura and its relationship with chromosomal inversion polymorphism

Latitudinal clinal variation in wing size and shape has evolved in North American populations of Drosophila subobscura within about 20 years since colonization. While the size cline is consistent to that found in original European populations (and globally in other Drosophila species), different parts of the wing have evolved on the two continents. This clearly suggests that 'chance and necessity' are simultaneously playing their roles in the process of adaptation. We report here rapid and consistent thermal evolution of wing shape (but not size) that apparently is at odds with that suggestion. Three replicated populations of D. subobscura derived from an outbred stock at Puerto Montt (Chile) were kept at each of three temperatures (13, 18 and 22 degrees C) for 1 year and have diverged for 27 generations at most. We used the methods of geometric morphometrics to study wing shape variation in both females and males from the thermal stocks, and rates of genetic divergence for wing shape were found to be as fast or even faster than those previously estimated for wing size on a continental scale. These shape changes did not follow a neat linear trend with temperature, and are associated with localized shifts of particular landmarks with some differences between sexes. Wing shape variables were found to differ in response to male genetic constitution for polymorphic chromosomal inversions, which strongly suggests that changes in gene arrangement frequencies as a response to temperature underlie the correlated changes in wing shape because of gene-inversion linkage disequilibria. In fact, we also suggest that the shape cline in North America likely predated the size cline and is consistent with the quite different evolutionary rates between inversion and size clines. These findings cast strong doubts on the supposed 'unpredictability' of the geographical cline for wing traits in D. subobscura North American colonizing populations.     

Geographical variation in wing polymorphism of the waterstrider Aquarius najas (Heteroptera,Gerridae)

The waterstrider Aquarius najas is wingless in Northern Europe, while winged individuals occur frequently in Central and Southern Europe. To test if the latitudinal difference is genetically controlled, we collected mature individuals from 10 different populations and raised their offspring in ‘common garden’ laboratory conditions. Half of these populations were from southern and the other half from central Finland. Daylength and temperature do influence wing development among other species of waterstriders, and thus we maintained a similar short daylength and warm conditions for all populations. These conditions should be favourable for wing development in general. Among laboratory-bred individuals several winged individuals appeared, and their proportion varied between populations. The relative frequency of winged individuals was highest in the southern populations. Thus, apart from phenotypic plasticity there seems to be some genetic control over the occurrence of wings, and the latitudinal trend coincides with the direction in natural populations over a larger European scale. Overwinter survival in our laboratory conditions was higher among the wingless individuals. The survival cost may explain why the proportion of winged individuals was lower in the northern populations with more extreme overwintering conditions than in the southern ones.     

Relationship between chromosomal polymorphism and wing size in a natural population of Drosophila subobscura

Chromosomal polymorphism and wing size (as a measure of body size) were analysed simultaneously in two samples of Drosophila subobscura from Barcelona, Spain. The very rich chromosomal polymorphism of this species makes it difficult to detect the relationship of this polymorphism with any phenotypical character. However, a positive significant regression of wing size on the percentage of the autosome length with standard arrangement was found. Furthermore, for each polymorphic chromosome, except for the J chromosome, an association between the most frequent arrangements and wing size was observed. This trend, which was the same in the two samples, was that expected according to the latitudinal clines of both characters.     

The primary feather lengths of early birds with respect to avian wing shape evolution

We examine the relationships between primary feather length (f(prim)) and total arm length (ta) (sum of humerus, ulna and manus lengths) in Mesozoic fossil birds to address one aspect of avian wing shape evolution. Analyses show that there are significant differences in the composition of the wing between the known lineages of basal birds and that mean f(prim) (relative to ta length) is significantly shorter in Archaeopteryx and enantiornithines than it is in Confuciusornithidae and in living birds. Based on outgroup comparisons with nonavian theropods that preserve forelimb primary feathers, we show that the possession of a relatively shorter f(prim) (relative to ta length) must be the primitive condition for Aves. There is also a clear phylogenetic trend in relative primary feather length throughout bird evolution: our analyses demonstrate that the f(prim)/ta ratio increases among successive lineages of Mesozoic birds towards the crown of the tree ('modern birds'; Neornithes). Variance in this ratio also coincides with the enormous evolutionary radiation at the base of Neornithes. Because the f(prim)/ta ratio is linked to flight mode and performance in living birds, further comparisons of wing proportions among Mesozoic avians will prove informative and certainly imply that the aerial locomotion of the Early Cretaceous Confuciusornis was very different to other extinct and living birds.     

Characterization and evolution of ovine MHC class II DQB sequence polymorphism

The second exons of OLA-DQB genes from 13 merino sheep were sequenced following amplification by the polymerase chain reaction or isolation from a cDNA library. Ten distinct exon 2 sequences, coding for 10 novel amino acid sequences, were characterized in these sheep. The single-strand conformation polymorphism technique was shown to be capable of discriminating between all sequences. This brings the total number of different OLA-DQB exon 2 sequences (nucleotide and amino acid) which have been characterized to 12, and demonstrates that the OLA-DQB region is highly polymorphic with 29% of nucleotide and 46% of amino acid sites showing variation. Evidence is presented that the OLA-DQB sequences belong to at least two lineages of DQB genes. Some ovine DQB sequences are more like bovine DQB counterparts than other ovine DQB sequences suggesting that the artiodactyl DQB gene and allele lineages predate the separation of the ovine and bovine species 20 million years ago.     

我多组学关联分析揭示表观等位基因在拟南芥环境适应性进化中的作用及机制

表观等位基因一般是指仅由DNA甲基化差异引起的表达量不同的等位基因,对植物形态结构和各种生理过程具有重要影响。但自然条件下环境因素对植物表观等位基因的影响还不清楚,同时表观等位基因在植物环境适应性进化中的作用和机制还亟待探究。为了在全基组水平鉴定拟南芥(Arabidopsis thaliana)中与特定环境因素相关的表观等位基因,并分析它们参与拟南芥环境适应性进化的可能机制,本研究利用623株拟南芥生态型的转录组、甲基化组和种源地气候数据进行多组学关联分析,并同时进行了蛋白互作网络和基因富集分析。以春季和夏季降水量为例,本研究最终鉴定到5个基因(AGL36、AT2G34100、AT4G09360、LSU4和AT5G56910)可能具有相应的表观等位基因,基因内部或附近特定区域不同甲基化水平对它们的表达可能具有调控作用。其中与种子发育有关的印记基因AGL36首次被发现可能作为表观等位基因参与拟南芥环境适应性进化,其他4个基因均与生物胁迫响应有关。自然条件下降水量能影响当地病虫害的严重程度,而DNA甲基化能通过影响这4个免疫基因的表达来影响拟南芥免疫能力。在长期演化过程中有利于个体适应当地降水模式的表观等位基因受到正向选择,这可能是这些表观等位基因参与拟南芥降水适应性进化的潜在机制。通过蛋白互作网络、GO功能分析和KEGG通路分析,本研究还首次发现LSU4可能与LSU基因家族其他成员一样参与硫代谢网络,并通过影响硫代葡萄糖苷代谢参与拟南芥生物胁迫响应。