非常规肌球蛋白与突触可塑性

突触可塑性是学习记忆的基础,其分子机制是理解记忆形成和维持的关键,也为神经退行性疾病的预防与治疗提供了新靶点。肌球蛋白超家族广泛存在于人体各种组织细胞中,主要分为常规肌球蛋白和非常规肌球蛋白。越来越多的研究发现,非常规肌球蛋白参与了许多重要的生命活动,尤其是在神经系统对突触可塑性的调节中,起到了十分重要的作用。     

果蝇钙调蛋白和肌球蛋白NINAC相互作用分析

果蝇的视觉信号转导途径是已知的最快的G 蛋白偶联信号通路。这其中涉及到TRP/TRPL通道的开放以及钙离子的内流等一系列反应的形成。NINAC（neither inactivation nor afterpotential C）是一种特异性存在于果蝇感光细胞中的第3类肌球蛋白（Myosin III）,其在终止果蝇的视觉信号转导通路中起着非常重要的作用。NINAC蛋白具有两种亚型：一种是132 kD的蛋白亚型 (p132),另一种则是174 kD的蛋白亚型(p174)。这两种不同的蛋白亚型都具有相同的激酶催化结构域(kinase domain),以及与肌球蛋白相似的马达结构域(motor domain)。但是,它们在C末端却存在着非常大的差异,这其中包括了钙调蛋白结合基序(IQ motif)。NINAC的这两种蛋白亚型在果蝇的感光细胞中的定位以及作用有很大不同,尤其是在与钙调蛋白的相互作用方面。钙调蛋白结合基序与钙调蛋白（CaM）之间的相互作用对于果蝇的视觉信号通路具有重要的意义：NINAC结合钙调蛋白能力的缺失将导致果蝇的视觉传导缺陷。本文通过蛋白共表达的方法,成功表达并纯化得到了不同版本的NINAC与钙调蛋白的蛋白复合物。静态光散射的结果表明,在Ca2+存在情况下,p174蛋白可以结合2个Ca2+-CaM,而p132只结合1个Ca2+-CaM。通过分析型凝胶过滤以及等温量热滴定技术,进一步鉴定了p174及p132的IQ2（第2个钙调蛋白结合基序）序列与Ca2+ CaM的相互作用。通过序列分析及进一步的突变实验发现,p174 IQ2中的3个疏水氨基酸（F1083,F1086 和 L1092）对于钙调蛋白的结合非常重要,并导致了p174与p132蛋白和Ca2+ CaM结合能力的差异。本文的研究提供了NINAC与Ca2+-CaM相互作用的生化机制,将为进一步在果蝇视觉信号通路中深入研究CaM是如何调节NINAC的体内功能实验打下基础。     

果蝇在行为遗传学研究中的重要性及其求爱行为的研究现状

果蝇是研究行为遗传学的良好材料。果蝇的性行为包括交尾前在视觉、听觉、嗅觉、触觉、刺激的传递和接受等方面相当复杂的“求爱行为”,受种特异性配偶认识系统的支配。雄果蝇的求爱歌包括正弦歌和脉冲歌,具有种的特异性。果蝇的信息素起“性引诱”作用,雌果蝇腹部的内部组织可能是产生某种信息素的场所。     

黑腹果蝇的性别控制

性别的形成包括两个过程,即性别决定和性别分化。果蝇的性别控制研究包括性别决定、性别分化、性别鉴定、性别诱导和性别控制5个方面。性别决定是在两种不同发育途径之间的选择,它提供了一个研究基因调控的模式系统。果蝇的性别决定问题已经研究得相当详细［1］。性别分化是使胚胎向着雌性或雄性发育的过程,决定了性别表型。果蝇的性别分化也取得了不少研究成果。近年来,许多重要的性别调控基因已被克隆和鉴定。随着果蝇基因组全序列测定的完成,果蝇的性别控制研究将会更为深入而完善。本文对与黑腹果蝇性别决定和性别分化相关的一些问题进行综述。     

伊米果蝇种组（Drosophila immigrans species group）H2a-H2b和Cyt b分子系统发育关系（简报）

伊米果蝇种组(Drosophila immigrans speciesgroup)是果蝇科(Drosophilidae)、果蝇属(Drosophi-la)、果蝇亚属(Drosophila)中数量最多的一个类群,主要分布于东洋区。在分类学上该种组分为nasuta、immigrans、hypocausta、quadrilineata和curviceps五个种亚组(species subgroup)[1],东洋区果蝇区系中伊米果蝇种组中包括94个种,其中有45个种分布在中国[2]。而且curviceps种亚组是1992年新建立的中国特有果蝇类群[3]。迄今,对伊米果蝇种组分子系统关系的报道还很少,有些物种的归属仍存在争议。伊米果蝇种组还有些问题需要探讨[4]。组蛋白基因…     

樱桃新害虫黑腹果蝇的生物学特性

果蝇是近几年发现危害樱桃果实的一类重要害虫,在国内外樱桃产区均有发生。天水地区危害甜樱桃的果蝇有3个种,分别是黑腹果蝇Drosophila melanogaster Meigen、铃木氏果蝇Drosophila suzukii(Matsumura)和海德氏果蝇Drosophila hydei(Sturtevant),黑腹果蝇为优势种。作者记述黑腹果蝇对甜樱桃果实的危害情况、寄主范围及其生活史、生活习性、发育历期与温度的关系等,调查发现蚂蚁是樱桃果蝇的天敌之一。     

果蝇幼虫的视觉系统

视觉对于动物的生存和行为来说是非常重要的。虽然果蝇幼虫的视觉神经系统在组织结构上比成虫简单,但是也具有一定的复杂性和多样性。在最近几年中,随着对果蝇幼虫视觉系统功能的研究取得重要进展,我们对于果蝇幼虫视觉系统的认识更加丰富了。果蝇幼虫视觉系统的结构中,最初级的光感受神经元包括三类,一类是BO/BN(Bolwig's organ/Bolwig's nerve),一类是表达感光分子CRY(cryptochrome)的神经元,另外一类是Ⅳ型DA(classⅣdendriticarborization)神经元;果蝇幼虫视觉系统的次级神经元主要是光节律相关的侧神经元(lateralneurons,LN),它表达Per(period)、Tim(timeless)及Pdf(pigment dispersion factor)等节律相关的蛋白分子;而第三级神经元包括更为下游的、表达果蝇促胸腺激素且直接调控幼虫光偏好的NP394神经元。这三级神经元构成了我们现在所了解的果蝇幼虫视觉神经系统的基本框架。     

模式动物果蝇的基因调控前沿技术

转基因调控技术在生命医学研究中扮演了重要的角色,是探究个体发育和致病机制的必备工具。常用的转基因调控技术包括基因突变、基因干扰和基因转录激活等。果蝇由于具有基因的保守性、遗传工具的多样性以及不受伦理限制等优势,成为生命科学研究中经典模式动物之一,并由此开发出了多种时间和组织特异性的基因调控工具。本文主要介绍了目前在果蝇中常用的基因调控技术,包括CRISPR/Cas9介导的基因突变系统、基于miRNA的新一代转基因干扰系统以及基于CRISPR/dCas9的转录激活(flySAM)系统,希望通过对这几种系统设计原理、操作过程、相关的技术工具及相关资源品系的介绍,提升人们对这些前沿的果蝇遗传学基因表达调控技术及构建的相关果蝇资源品系重要性认识,进而推动生命医学研究发展。     

果蝇抗微生物肽基因的免疫诱导模式

果蝇作为一种模式昆虫,为研究昆虫和人类的先天免疫发挥了重要作用。目前对果蝇体内免疫诱导产生的抗微生物肽多基因家族在分子进化、抗菌功能的分子特征和免疫诱导表达的信号传递机制等方面的研究进展,进一步加深了人们对昆虫乃至其他动物和人类先天免疫模式的认识,为研究其他昆虫特别是作为主要农林害虫的鳞翅目昆虫的先天免疫机制发挥了重要作用。本文集中对黑腹果蝇Drosophila melanogaster抗微生物肽及其免疫模式的研究结果和最新进展进行了介绍,其中包括作者近几年的研究结果。     

果蝇属拱背果蝇亚属七新种：（双翅目：果蝇科）

本文记述果蝇属Drosophila拱背果蝇亚属Lordiphosa在中国的分布,包括七新种:等枝拱背果蝇Drosophila (Lordiphosa) ramipata sp.nov.,不对称拱背果蝇Drosophila (Lordiphosa) acongruens sp.nov.,突弓拱背果蝇Drosophila (Lordiphosa) protrusa sp.nov.,多枝拱背果蝇Drosopkila (Lordiphota) ramosisslma sp.nov.,双突拱背果蝇Drosophila (Lordiphosa) biconvexa sp.nov.,黑拱背果蝇Drosophila (Lordiphosa) picea sp.nov.,和黄拱背果蝇Drosophila (Lordiphosa) flava sp.nov.     

Identification and phylogenetic analysis of Drosophila melanogaster myosins

Myosins constitute a superfamily of motor proteins that convert energy from ATP hydrolysis into mechanical movement along the actin filaments. Phylogenetic analysis currently places myosins into 17 classes based on class-specific features of their conserved motor domain. Traditionally, the myosins have been divided into two classes depending on whether they form monomers or dimers. The conventional myosin of muscle and nonmuscle cells forms class II myosins. They are complex molecules of four light chains bound to two heavy chains that form bipolar filaments via interactions between their coiled-coil tails (type II). Class I myosins are smaller monomeric myosins referred to as unconventional myosins. Now, at least 15 other classes of unconventional myosins are known. How many myosins are needed to ensure the proper development and function of eukaryotic organisms? Thus far, three types of myosins were found in budding yeast, six in the nematode Caenorhabditis elegans, and at least 12 in human. Here, we report on the identification and classification of Drosophila melanogaster myosins. Analysis of the Drosophila genome sequence identified 13 myosin genes. Phylogenetic analysis based on the sequence comparison of the myosin motor domains, as well as the presence of the class-specific domains, suggests that Drosophila myosins can be divided into nine major classes. Myosins belonging to previously described classes I, II, III, V, VI, and VII are present. Molecular and phylogenetic analysis indicates that the fruitfly genome contains at least five new myosins. Three of them fall into previously described myosin classes I, VII, and XV. Another myosin is a homolog of the mouse and human PDZ-containing myosins, forming the recently defined class XVIII myosins. PDZ domains are named after the postsynaptic density, disc-large, ZO-1 proteins in which they were first described. The fifth myosin shows a unique domain composition and a low homology to any of the existing classes. We propose that this is classified when similar myosins are identified in other species.     

Regulation of calmodulin-binding myosins

Myosins constitute a diverse superfamily of actin-based mechanoenzymes that are involved in many essential cellular motilities. In addition to conventional muscle myosin II, ten other classes of unconventional myosins are known. Many unconventional myosins bind multiple calmodulin light chains and Ca2+, which can dramatically alter their mechanochemical and enzymatic activity. Calmodulin-binding myosins can also be regulated by phospholipid binding, phosphorylation of the heavy chain and actin-binding proteins. The molecular details linking unconventional-myosin regulation and function are just beginning to emerge.     

Left-right asymmetry: class I myosins show the direction

Myosins are actin-based molecular motors that are found in almost all eukaryotes. Phylogenetic analysis allows the discrimination of 37 different types of myosins, most with unknown functions. Recent work in Drosophila has revealed a crucial role for type ID unconventional myosin in left-right asymmetry. Mutations in Myosin ID completely reverse the left-right axis (situs inversus), a phenotype that is dependent on an intact actin cytoskeleton. How this myosin might orient the left-right axis has began to be elucidated by showing that it interacts directly with beta-catenin, suggesting that myosin ID interacts with the adherens junction to control the direction of organ looping. This is the first demonstration of a role of a myosin in body patterning.     

Different subcellular localizations and functions of Arabidopsis myosin VIII

Background  

Myosins are actin-activated ATPases that use energy to generate force and move along actin filaments, dragging with their tails different cargos. Plant myosins belong to the group of unconventional myosins and Arabidopsis myosin VIII gene family contains four members: ATM1, ATM2, myosin VIIIA and myosin VIIIB.     

Myosins: a diverse superfamily

Myosins constitute a large superfamily of actin-dependent molecular motors. Phylogenetic analysis currently places myosins into 15 classes. The conventional myosins which form filaments in muscle and non-muscle cells form class II. There has been extensive characterization of these myosins and much is known about their function. With the exception of class I and class V myosins, little is known about the structure, enzymatic properties, intracellular localization and physiology of most unconventional myosin classes. This review will focus on myosins from class IV, VI, VII, VIII, X, XI, XII, XIII, XIV and XV. In addition, the function of myosin II in non-muscle cells will also be discussed.     

Regulation of the enzymatic and motor activities of myosin I

Myosins I were the first unconventional myosins to be purified and they remain the best characterized. They have been implicated in various motile processes, including organelle translocation, ion channel gating and cytoskeletal reorganization but their exact cellular functions are still unclear. All members of the myosin I family, from yeast to man, have three structural domains: a catalytic head domain that binds ATP and actin; a tail domain believed to be involved in targeting the myosins to specific subcellular locations and a junction or neck domain that connects them and interacts with light chains. In this review we discuss how each of these three domains contributes to the regulation of myosin I enzymatic activity, motor activity and subcellular localization.     

Mapping of Unconventional Myosins in Mouse and Human

Myosins are molecular motors that move along filamentous actin. Seven classes of myosin are expressed in vertebrates: conventional myosin, or myosin-II, as well as the 6 unconventional myosin classes -I, -V, -VI, -VII, -IX, and -X. We have mapped in mouse 22 probes encompassing all known unconventional myosins and, as a result, have identified 16 potential unconventional myosin genes. These genes include 7 myosins-I, 2 myosins-V, 1 myosin-VI, 3 myosins-VII, 2 myosins-IX, and 1 myosin-X. The map location of 5 of these genes was identified in human chromosomes by fluorescencein situhybridization.     

Unique sequences and predicted functions of myosins in Tetrahymena thermophila

Myosins are eukaryotic actin-dependent molecular motors that play important roles in many cellular events. The function of each myosin is determined by a variety of functional domains in its tail region. In some major model organisms, the functions and properties of myosins have been investigated based on their amino acid sequences. However, in protists, myosins have been little studied beyond the level of genome sequences. We therefore investigated the mRNA expression levels and amino acid sequences of 13 myosin genes in the ciliate Tetrahymena thermophila. This study is an overview of myosins in T. thermophila, which has no typical myosins, such as class I, II, or V myosins. We showed that all 13 myosins were expressed in vegetative cells. Furthermore, these myosins could be divided into 3 subclasses based on four functional domains in their tail regions. Subclass 1 comprised of 8 myosins has both MyTH4 and FERM domains, and has a potential to function in vesicle transport or anchoring between membrane and actin filaments. Subclass 2 comprised of 4 myosins has RCC1 (regulator of chromosome condensation 1) domains, which are found only in some protists, and may have unconventional features. Subclass 3 is comprised of one myosin, which has a long coiled-coil domain like class II myosin. In addition, phylogenetic analysis on the basis of motor domains showed that T. thermophila myosins are separated into two clusters: one consists of subclasses 1 and 2, and the other consists of subclass 3.     

Characterization of the unconventional myosin VIII in plant cells and its localization at the post-cytokinetic cell wall

Myosins are a large superfamily of motor proteins which, in association with actin, are involved in intra- cellular motile processes. In addition to the conventional myosins involved in muscle contractility, there is, in animal cells, a wide range of unconventional myosins implicated in membrane-associated processes, such as vesicle transport and membrane dynamics. In plant cells, however, very little is known about myosins. We have raised an antibody to the recombinant tail region of Arabidopsis thaliana myosin 1 (a class VIII myosin) and used it in immunofluorescence and EM studies on root cells from cress and maize. The plant myosin VIII is found to be concentrated at newly formed cross walls at the stage in which the phragmoplast cytoskeleton has depolymerized and the new cell plate is beginning to mature. These walls are rich in plasmodesmata and we show that they are the regions where the longitudinal actin cables appear to attach. Myosin VIII appears to be localized in these plasmodesmata and we suggest that this protein is involved in maturation of the cell plate and the re-establishment of cytoplasmic actin cables at sites of intercellular communication.