绿盲蝽中枢神经系统的解剖结构

【目的】阐述绿盲蝽Apolygus lucorum中枢神经系统的组成,辨识各组成部分的神经节解剖结构及其形态,计算中枢神经系统各神经节结构体积大小、解析其空间分布关系以及连接模式。【方法】采用免疫组织化学方法,使用突触蛋白抗体对绿盲蝽中枢神经系统神经髓进行染色标记,利用共聚焦激光扫描显微镜获取中枢神经系统各结构数码图像,使用三维图像分析软件对绿盲蝽中枢神经系统进行分析,并构建三维模型。【结果】绿盲蝽中枢神经系统从前往后分别由脑神经节、咽下神经节、前胸神经节和后部神经节组成。脑、咽下神经节和前胸神经节3个神经节融合在一块,形成脑-咽下神经节-前胸神经节复合体,并通过长的神经连索与后部神经节相连,从外观上看似由2个大的神经节构成,这种神经节愈合形式尚未在昆虫中发现过。前胸神经节与后部神经节分离,二者由长的神经连索连接起来。除前胸神经节由单独的神经原节构成外,其他3个神经节又由多个神经原节融合而成。脑包括前脑、中脑和后脑3部分。咽下神经节包括上颚神经节、下颚神经节和下唇神经节。后部神经节包括中胸、后胸和腹部神经节3部分。【结论】明确了绿盲蝽中枢神经系统的神经节构成,发现了绿盲蝽中枢神经系统各神经节的高度融合特性。该项研究结果为研究绿盲蝽中枢神经系统的发育、重塑和系统演化奠定了形态学基础,为研究中枢神经元形态、分布以及其对昆虫生理和行为的功能调控机制提供了结构框架。     

5-羟色胺在粘虫视叶中的分布

【目的】解剖分析粘虫Mythimna separata成虫视叶的结构,研究5-羟色胺(5-hydroxytryptamine,5-HT)在视叶中的分布。【方法】采用组织包埋切片技术和免疫组织化学方法,使用突触蛋白抗体标记粘虫成虫视叶内神经髓结构,用抗5-HT血清标记5-HT;利用激光共聚焦扫描显微镜照相获取数码图像,利用图形分析软件识别神经髓结构及进行细胞体群分组与计数。【结果】粘虫成虫的视叶由视神经节层、视髓、副视髓、视小叶和视小叶板5个神经髓结构组成。免疫染色显示粘虫视叶内具有5-HT,每个视叶内约具有40个5-HT免疫标记的细胞体,这些细胞体分为3个细胞体群,位于视髓前方或腹面的内侧。视叶内所有的神经髓结构均含有5-HT免疫标记神经纤维。视神经节层的5-HT免疫标记神经纤维来自视叶的切向神经元,视髓的5-HT免疫标记神经纤维主要来自视叶的切向神经元、远心神经元和无长突神经元。视髓呈明显分层现象,主要分为3层,其中中间一层5-HT免疫标记神经纤维较密集。副视髓存在少量的5-HT免疫标记神经纤维。视小叶和视小叶板中的5-HT免疫标记神经纤维来自远心神经元,分为明显的2层,其中有少量神经纤维投射至视髓,将视小叶、视小叶板和视髓连接起来。【结论】粘虫视叶中广泛分布着5-HT免疫标记神经纤维。该研究结果为进一步研究5-HT在视觉机制中的作用奠定一定的解剖学基础。     

绿盲蝽体内寄主植物DNA提取方法的优化

【目的】优化绿盲蝽Apolygus lucorum体内植物DNA提取方法,为绿盲蝽寄主利用习性研究发展DNA分子追踪技术。【方法】首先分别利用CTAB法、两种试剂盒法提取绿盲蝽中肠内DNA样本,比较分析其中的棉花DNA检出率。其次,利用1%~1.5%的次氯酸钠溶液漂洗绿盲蝽成虫,比较不同漂洗处理对绿盲蝽体表植物DNA的清除效率以及对体内棉花DNA检出率。【结果】不同提取方法对绿盲蝽中肠内棉花DNA检出率存在显著影响,其中CTAB法提取的中肠样本中棉花DNA的检出率最高。将绿盲蝽成虫在1%~1.5%次氯酸钠中漂洗5 s,可清除成虫体表的植物DNA污染,且不破坏体内的棉花DNA;漂洗30 s后,体内棉花DNA检出率明显降低。【结论】本研究证实了利用整头绿盲蝽成虫代替其中肠提取的绿盲蝽DNA样本的可行性,并明确了成虫体内植物DNA高效提取的方法,为进一步利用DNA分子追踪技术研究绿盲蝽田间寄主选择与取食行为奠定了重要基础。     

绿盲蝽八个普通气味受体基因的克隆及功能鉴定

【目的】本研究旨在克隆绿盲蝽Apolygus lucorum的气味受体基因,明确这些气味受体基因在绿盲蝽成虫不同组织中的表达水平及对主要寄主植物挥发物的电生理反应,为揭示绿盲蝽对寄主植物的识别机制提供理论基础。【方法】在绿盲蝽成虫触角转录组测序与分析的基础上,通过PCR技术克隆得到8个具有完整ORF的气味受体基因序列。用qPCR研究这8个基因在雌雄成虫不同组织(触角、无触角的头、胸、腹、足和翅)中的表达水平。然后通过爪蟾卵母细胞体外表达结合双电极电压钳技术测试这些气味受体对56种气味化合物的电生理反应。【结果】克隆得到了绿盲蝽8个气味受体基因AlucOR9, AlucOR16,AlucOR38, AlucOR53, AlucOR55, AlucOR56, AlucOR57和AlucOR58的cDNA全长序列(GenBank登录号:MN905538-MN905545)。这些气味受体含有7个跨膜结构域,且N末端位于胞内,C末端位于胞外,符合昆虫气味受体的典型特征。qPCR结果表明,这8个气味受体基因均在绿盲蝽成虫触角中高表达,而在其他组织中低表达,其中除AlucOR38外的其他7个气味受体基因在雌雄成虫触角间存在显著的表达差异。双电极电压钳记录结果显示,AlucOR57对其中15种气味化合物(苯甲醛、氧化石竹烯、庚醛、反-2-己烯醛、乙酸苯甲酯、桃金娘烯醛、4-乙基苯甲醛、乙酸壬酯、四氢芳樟醇、十三烷、反-3-己烯醇、2-丙烯酸丁酯、丙酸丁酯、乙酸辛酯和乙酸戊酯)有反应,其余7个气味受体对测试的全部气味化合物均无反应。【结论】AlucOR57对测试的一些气味化合物有反应,推测其在绿盲蝽的寄主识别过程中发挥重要作用;其他7个气味受体对测试气味化合物均无反应,其功能有待进一步研究。     

黑肩绿盲蝽耐饥饿能力的研究

【目的】为早期释放黑肩绿盲蝽Cyrtorhinus lividipennis提供理论依据,研究了黑肩绿盲蝽不同虫态耐受饥饿及低温的能力。【方法】室内条件下,比较了稻苗+水、无苗有水和无苗无水三种食物条件下黑肩绿盲蝽耐饥力大小。【结果】适温(26℃)下,黑肩绿盲蝽3龄若虫、5龄若虫和成虫在稻苗+水的存活时间显著高于无苗有水,无苗有水时的存活时间又显著高于无苗无水,表明稻苗对于黑肩绿盲蝽有营养作用,取食稻苗有助于提高黑肩绿盲蝽的耐饥力。黑肩绿盲蝽成虫耐饥力最强,3龄若虫和5龄若虫接近,有苗有水时,3龄若虫、5龄若虫和成虫的平均存活时间分别为2.10、2.22和4.25 d。在低温(15℃)下,水稻苗对黑肩绿盲蝽成虫的存活不利,有苗有水时雌雄成虫的存活时间均低于无苗有水处理,其中雌成虫两处理间的差异显著(P=0.001)。【结论】黑肩绿盲蝽对饥饿和低温有较强的耐受性,以成虫最强,水稻生长前期田间释放时以成虫为宜。     

一种快速鉴别柑橘潜叶蛾蛹及成虫雌雄的简易方法

【目的】柑橘潜叶蛾Phyllocnistis citrella Stainton是柑橘重要害虫,本研究拟建立一种快速鉴别柑橘潜叶蛾蛹及成虫性别的简易方法。【方法】利用体视显微镜观察、拍照记录柑橘潜叶蛾蛹和成虫的腹部末端形态特征并进行比较分析,待蛹羽化后进行解剖验证结果。【结果】与柑橘潜叶蛾雄蛹相比,雌蛹的第7腹节下缘分界线不明显,生殖孔和肛门分别在第8腹节和第10腹节,而雄蛹的第7腹节下缘分界线明显,生殖孔在第9腹节,肛门在第10腹节。柑橘潜叶蛾雌成虫腹部末端呈圆筒形,而雄成虫腹部末端相对尖细;轻轻按压成虫腹部,雌蛾在末端伸出部分的两侧有黑斑,而雄蛾在末端伸出部分的两侧没有黑斑,但有一对长毛簇,在伸出的同时散开。该方法能快速鉴别柑橘潜叶蛾蛹及成虫的性别,其准确率为100%。【结论】通过比较柑橘潜叶蛾雌雄蛹生殖孔及肛门的位置,可以准确区分雌雄蛹;轻压并观察雌雄成虫腹部伸出末端黑斑或长毛簇的有无可有效区分成虫性别。     

烟青虫成虫脑结构解剖和三维模型构建

【目的】解剖分析烟青虫 Helicoverpa assulta 成虫脑的结构,并构建脑三维结构数字化模型。【方法】利用神经突触蛋白抗体,对烟青虫成虫脑进行免疫组织化学染色标记,利用共聚焦激光扫描显微镜获得脑扫描数码图像,并结合三维图像分析软件对烟青虫脑结构进行识别分析,构建三维模型。【结果】突触蛋白抗体免疫染色将烟青虫脑和颚神经节的神经髓区域清晰标记出来。烟青虫成虫脑与颚神经节愈合而成为一体,中间具有一个孔洞,为食道穿过的通道。脑主要包括前脑、中脑和后脑3部分。依据染色标记结果识别和构建了至少16个脑神经髓结构。这些神经髓包括边界清晰的视叶、前视结节、蕈形体、中央复合体和触角叶及其亚结构。除此之外,还包括围绕这些神经髓的其他前脑神经髓区域,但这部分前脑神经髓内部边界模糊,不容易细分,而将其与颚神经节区域作为一个整体标记为中间脑,占脑总神经髓的55.05%。【结论】识别出烟青虫脑的主要功能结构区域,并成功构建了三维模型。该研究结果为进一步研究烟青虫脑接收、处理和整合感觉信息及调控行为的机制奠定了解剖学基础,并为研究烟青虫或其他昆虫脑结构发育、变异和重塑提供结构形态和体积大小依据。     

应用瓶膜法和人工饲料混合法测定比较16种杀虫剂对绿盲蝽的毒力（英文）

【目的】绿盲蝽Apolygus lucorum(Meyer-Dür)是我国Bt棉田内一类重要的刺吸性害虫。有机磷类和菊酯类杀虫剂因其对绿盲蝽具有较高的触杀毒力,是当前Bt棉田内广泛应用的杀虫剂,而新烟碱类杀虫剂因其较低的触杀毒力而没有被推荐使用。但在田间试验中,用新烟碱类杀虫剂处理棉种能够有效减少苗期至开花期绿盲蝽的危害。因此,亟待需要一种准确的毒力测定方法,以重新评价新烟碱类杀虫剂对绿盲蝽的毒力。【方法】本研究在成功研制绿盲蝽人工饲料的基础上,应用瓶膜法和人工饲料混合法两种毒力测定方法测定比较了5类16种杀虫剂对绿盲蝽3龄若虫和成虫的毒力。【结果】应用瓶膜法,新烟碱类杀虫剂对绿盲蝽成虫和若虫的LC_(50)值在337.97~496.03μg/mL范围内,显著高于其他类型的杀虫剂(LC_(50)值范围在0.28~207.26μg/mL)。然而,应用人工饲料混合法,新烟碱类杀虫剂对绿盲蝽成虫和若虫的LC_(50)值在0.01~1.08μg/g,与其他类杀虫剂LC_(50)值相等甚至低于其他类杀虫剂。【结论】结果表明新烟碱类杀虫剂对绿盲蝽的胃毒毒力显著强于它的触杀毒力,可用于绿盲蝽的田间防治。推荐人工饲料混合法作为监测绿盲蝽对新烟碱类杀虫剂抗性发展的一个替代方法。     

棉铃虫幼虫脑和咽下神经节的三维结构构建

【目的】解剖棉铃虫Helicoverpa armigera (Hübner) 5龄幼虫脑和咽下神经节及其内部神经髓形态结构,并分析和构建幼虫脑和咽下神经节以及各神经髓的三维结构模型。【方法】采用免疫组织化学方法解剖脑和咽下神经节的内部神经髓结构,利用激光共聚焦显微镜获取脑和咽下神经节扫描图像,然后利用AMIRA 三维图像分析软件进行图像分析,从而构建脑和咽下神经节的三维结构模型,并测量脑和咽下神经节以及内部各神经髓的体积,并分析了相对比例。【结果】 棉铃虫5龄幼虫脑和咽下神经节由围咽神经索连接在一起。脑主要由前脑、中脑和后脑3部分组成。前脑内包括视叶、蕈形体和中央体等形态结构较明显的神经髓。此外,前脑还包括其他位于脑的左右两侧以及背侧和腹侧大量神经髓区域,约占脑总神经髓的59.65%。这些神经髓区域边界不明显。中脑主要包括1对触角叶;后脑位于脑的腹侧和触角叶的下方,体积较小。咽下神经节由3个神经节融合构成,从前到后分别为上颚神经节、下颚神经节和下唇神经节,由于融合的紧密程度高,3个神经节间的边界不明显。【结论】阐明了棉铃虫5龄幼虫脑和咽下神经节的神经髓形态结构,构建了脑和咽下神经节以及内部神经髓的三维结构模型。三维模型可以任意旋转,能从任何角度观察脑、咽下神经节和内部不同神经髓的结构及其它们之间的空间关系。本研究结果对研究棉铃虫脑和咽下神经节信息接收、处理及调控行为的机制奠定了解剖学基础。     

桔小实蝇视叶结构特征及5-羟色胺能神经元的分布

桔小实蝇是重要的果蔬害虫,它对不同颜色的光表现出不同的趋性。为了明确其视觉感受的结构基础,本研究采用免疫组织化学染色技术结合激光共聚焦成像分析了桔小实蝇成虫视叶内神经髓结构组成和体积大小,并利用5-羟色胺(5-hydroxytryptamine,5-HT)抗体标记了视叶内5-羟色胺能神经元,研究了其在视叶内的分布特征及细胞体数量。结果表明,桔小实蝇成虫的视叶由视神经节层、视髓、副视髓、视小叶和视小叶板5个神经髓结构组成,其中雌成虫的视髓相对体积极显著的大于雄虫的视髓相对体积。桔小实蝇每个视叶中包含12个5-HT能神经元细胞体,位于视髓的腹内侧,副视髓的前方。视叶5个神经髓区均含5-HT能神经纤维,但它们的神经纤维来自不同的神经元。对视叶神经髓结构及5-HT能神经元分布特征的研究将为未来构建桔小实蝇视觉神经通路和阐明5-HT对视觉感受的调控机制奠定解剖学基础。     

Localization of cholecystokinin-like immunoreactivity in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.     

CNS microstructure in the wandering wolf spider Arctosa kwangreungensis (Araneae: Lycosidae)

The supraesophageal ganglion of the wolf spider Arctosa kwangreungensis is made up of a protocerebral and tritocerebral ganglion, whereas the subesophageal ganglionic mass is composed of a single pair of pedipalpal ganglia, four pairs of appendage ganglia, and a fused mass of abdominal neuromeres. In the supraesophageal ganglion, complex neuropile masses are located in the protocerebrum which include optic ganglia, the mushroom bodies, and the central body. Characteristically, the only nerves arising from the protocerebrum are the optic nerves, and the neuropiles of the principal eyes are the most thick and abundant in this wandering spider. The central body which is recognized as an important association center is isolated at the posterior of the protocerebrum and appears as a complex of highly condensed neurons. These cells give off fine parallel bundles of axons arranged in the mushroom bodies. The subesophageal nerve mass can be divided into two main tracts on the basis of direction of the neuropiles. The dorsal tracts are contributed to from the motor or interneurons of each ganglion, whereas the ventral tracts are from incoming sensory axons.     

Fine structure of cardiac ganglion trunk in prawn, Penaeus japonicus bates.

The cardiac ganglion trunk of prawn, Peneaus japonicus Bates, is on the middle line of ventral wall of the cardiac tube and consists of nine ganglion cells, many nerve fibers and neuropils. These neuronal elements are insulated by supporting cells and connective tissue fibers. The peripheral area of the perikaryal cytoplasm of the ganglion cell is separated into many compartments by deep invaginations of the cell membrane. Each compartment is packed with a tight network of the agranular endoplasmic reticulum. Among nerve fiber bundles are many small areas of neuropil. Most of the synapses in the ganglion trunk are observed in the neuropil, but there are a few nerve terminals which form synapses with the somata of ganglion cells.     

The distribution of GABA-like immunoreactivity in relation to ganglion structure in the abdominal nerve cord of the locust (Schistocerca gregaria)

Summary An antiserum raised against GABA was used to stain the abdominal nervous system of the locust. To interpret the results, however, it was first necessary to describe the structure of the free abdominal and terminal ganglia. This was done on the basis of ethyl-gallate staining. The free abdominal ganglia are similar in structure to the abdominal neuromeres of the metathoracic ganglia. The terminal ganglion is composed of four neuromeres (representing ganglia 8–11), but only three can be distinguished in the adult on morphological grounds. The eighth neuromere resembles the free ganglia, but the ninth lacks DCI (dorsal commissure I) and the T tracts. In the tenth, only DCII and III are recognisable of the commissures, but two more posterior ones of uncertain homology are also present. Immunocytochemistry reveals three populations of somata in each abdominal ganglion. Of these only one, the medial posterior group, is found in the thoracic ganglia. DCIV and the supra-median commissure are composed of stained neurites, DCII and V contain both unstained neurites and DCI, III and VI are unstained. With the exception of the median ventral tract, all the longitudinal tracts contain some stained axons.     

Architecture of the nervous system in mystacocarida (Arthropoda,crustacea)—An immunohistochemical study and 3D reconstruction

Mystacocarida is a species‐poor group of minute crustaceans with unclear phylogenetic affinities. Previous studies have highlighted the putative “primitiveness” of several mystacocarid features, including the architecture of the nervous system. Recent studies on arthropod neuroarchitecture have provided a wealth of characters valuable for phylogenetic reconstructions. To permit and facilitate comparison with these data, we used immunohistochemical labeling (against acetylated α‐tubulin, serotonin and FMRFamide) on the mystacocarid Derocheilocaris remanei, analyzing it with confocal laser‐scanning microscopy and 3D reconstruction. The mystacocarid brain is fairly elongated, exhibiting a complicated stereotypic arrangement of neurite bundles. However, none of the applied markers provided evidence of structured neuropils such as a central body or olfactory glomeruli. A completely fused subesophageal ganglion is not present, all segmental soma clusters of the respective neuromeres still being delimitable. The distinct mandibular commissure comprises neurite bundles from more anterior regions, leading us to propose that it may have fused with an ancestral posterior tritocerebral commissure. The postcephalic ventral nervous system displays a typical ladder‐like structure with separated ganglia which bears some resemblance to larval stages in other crustaceans. Ganglia and commissures are also present in the first three limbless “abdominal” segments, which casts doubt on the notion of a clear‐cut distinction between thorax and abdomen. An unpaired longitudinal median neurite bundle is present and discussed as a potential tetraconate autapomorphy. Additionally, a paired latero‐longitudinal neurite bundle extends along the trunk. It is connected to the intersegmental nerves and most likely fulfils neurohemal functions. We report the complete absence of serotonin‐ir neurons in the ventral nervous system, which is a unique condition in arthropods and herein interpreted as a derived character. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

The organization of plurisegmental mechanosensitive interneurons in the central nervous system of the wandering spider Cupiennius salei

Summary In spiders the bulk of the central nervous system (CNS) consists of fused segmental ganglia traversed by longitudinal tracts, which have precise relationships with sensory neuropils and which contain the fibers of large plurisegmental interneurons. The responses of these interneurons to various mechanical stimuli were studied electrophysiologically, and their unilateral or bilateral structure was revealed by intracellular staining. Unilateral interneurons visit all the neuromeres on one side of the CNS. They receive mechanosensory input either from a single leg or from all ipsilateral legs via sensory neurons that invade leg neuromeres and project into specific longitudinal tracts. The anatomical organization of unilateral interneurons suggests that their axons impart their information to all ipsilateral leg neuromeres. Bilateral interneurons are of two kinds, symmetric and asymmetric neurons. The latter respond to stimulation of all legs on one side of the body, having their dendrites amongst sensory tracts of the same side of the CNS. Anatomical evidence suggests that their terminals invade all four contralateral leg neuromeres. Bilaterally symmetrical plurisegmental interneurons have dendritic arborizations in both halves of the fused ventral ganglia. They respond to the stimulation of any of the 8 legs. A third class of cells, the ascending neurons have unilateral or bilateral dendritic arborizations in the fused ventral ganglia and show blebbed axons in postero-ventral regions of the brain. Their response characteristics are similar to those of other plurisegmental interneurons. Descending neurons have opposite structural polarity, arising in the brain and terminating in segmental regions of the fused ventral ganglia. Descending neurons show strong responses to visual stimulation. Approximately 50% of all the recorded neurons respond exclusively to stimulation of a single type of mechanoreceptor (either tactile hairs, or trichobothria, or slit sensilla), while the rest respond to stimulation of a variety of sensilla. However, these functional differences are not obviously reflected by the anatomy. The functional significance of plurisegmental interneurons is discussed with respect to sensory convergence and the coordination of motor output to the legs. A comparison between the response properties of certain plurisegmental interneurons and their parent longitudinal tracts suggests that the tracts themselves do not reflect a modality-specific organization.Abbreviations BPI bilateral plurisegmental interneuron - CNS central nervous system - FVG fused ventral ganglia - LT longitudinal tract - PI plurisegmental interneuron - PSTH peristimulus timehistogram - UPI unilateral plurisegmental interneuron     

The distribution of pheromone-biosynthesis-activating neuropeptide (PBAN) immunoreactivity in the central nervous system of the corn earworm moth,Helicoverpa zea

Summary Production of sex pheromone in several species of moths has been shown to be under the control of a neuropeptide termed pheromone-biosynthesis-activating neuropeptide (PBAN). We have produced an antiserum to PBAN from Helicoverpa zea (Lepidoptera: Noctuidae) and used it to investigate the distribution of immunoreactive peptide in the brain-suboesophageal ganglion complex and its associated neurohemal structures, and the segmental ganglia of the ventral nerve cord. Immunocytochemical methods reveal three clusters of cells along the ventral midline in the suboesophageal ganglion (SOG), one cluster each in the presumptive mandibular (4 cells), maxillary (12–14 cells), and labial neuromeres (4 cells). The proximal neurites of these cells are similar in their dorsal and lateral patterns of projection, indicating a serial homology among the three clusters. Members of the mandibular and maxillary clusters have axons projecting into the maxillary nerve, while two additional pairs of axons from the maxillary cluster project into the ventral nerve cord. Members of the labial cluster project to the retrocerebral complex (corpora cardiaca and cephalic aorta) via the nervus corpus cardiaci III (NCC III). The axons projecting into the ventral nerve cord appear to arborize principally in the dorsolateral region of each segmental ganglion; the terminal abdominal ganglion is distinct in containing an additional ventromedial arborization in the posterior third of the ganglion. Quantification of the extractable immunoreactive peptide in the retrocerebral complex by ELISA indicates that PBAN is gradually depleted during the scotophase, then restored to maximal levels in the photophase. Taken together, our findings provide anatomical evidence for both neurohormonal release of PBAN as well as axonal transport via the ventral nerve cord to release sites within the segmental ganglia.Abbreviations A aorta - Br-SOG brain-suboesophageal ganglion complex - CC corpus cardiacum - PBS phosphate-buffered saline - PLI PBAN-like immunoreactivity - TAG terminal abdominal ganglion - VNC ventral nerve cord     

The adult ventral nerve cord as a phylogenetic character in brachyceran Diptera

Insect ganglia are often composed of fused segmental units or neuromeres. We estimated the evolution of the ventral nerve cord (VNC) in higher Diptera by comparing the patterns of neuromere fusion among 33 families of the Brachycera. Variation within families is uncommon, and VNC architecture does not appear to be influenced by body shape. The outgroup pattern, seen in lower Diptera, is fusion of neuromeres belonging to thoracic segments 1 and 2 (T1 and T2), and fusion of neuromeres derived from T3 and abdominal segment 1 (A1). In the abdomen, neuromeres A7–10 are fused into the terminal abdominal ganglion (TAG). Increased neuromere fusion is a feature of the Brachycera. No brachyceran shows less fusion than the outgroups. We established six pattern elements: (1) fusion of T1 and T2, (2) fusion of T3 and A1, (3) fusion of the T1/T2 and T3/A1 ganglia, (4) increase in the number of neuromeres comprising the TAG, (5) anteriorward fusion of abdominal neuromeres, and (6) the complete fusion of thoracic and abdominal neuromeres into a synganglion. States 1 and 2 are present in the outgroup lower Diptera, and state 3 in the Xylophagomorpha, Stratiomyomorpha, Tabanomorpha and Cyclorrhapha. State 4 is a feature of all Eremoneura. State 5 is present in Cyclorrhapha only, and state 6, fusion into a synganglion, has evolved at least 4 times in the Eremoneura. Synapomorphies are provided for the Cyclorrhapha and Muscoidea, and a grouping of three basal brachyceran infraorders Xylophagomorpha, Stratiomyomorpha and Tabanomorpha. The patterns of fusion suggest that VNC architecture has evolved irreversibly, in accordance with Dollo's law.     

GABA-like immunoreactivity in the suboesophageal ganglion of the locust Schistocerca gregaria

Summary Neurones in the suboesophageal ganglion of the locust Schistocerca gregaria were stained with an antiserum raised against gamma amino butyric acid (GABA). This ganglion consists of the fused mandibular, maxillary and labial neuromeres. Immunoreactive cell bodies of similar size and distribution occur in the lateral, ventral and middorsal regions of all three neuromeres. Approximately 200 cell bodies stain in both the mandibular and maxillary neuromeres and 270 in the labial neuromere. A few distinctly larger cells occur in the ventral groups and one large pair occurs in the lateral group of the maxillary neuromere. Dorsal commissures DCIV and DCV are composed mainly of stained fibres, while DCI–DCIII are largely unstained. A ventral commissure also stains in the maxillary neuromere. All longitudinal tracts contain both stained and unstained fibres. Many processes within the neuropil are also immunoreactive. A stained axon is found in the posterior tritocerebral commissure which enters the anterior dorsal region of the mandibular neuromere. The salivary branch of the 7th nerve contains one stained axon and two axons stain in nerve 8 which innervates neck muscles.