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1.
众所周知,飞蛾和蝴蝶,尤其是家蚕,是产丝的好手。我们也都知道蜘蛛吐丝结网。但是它们并不是无脊椎动物中唯一利用这种强壮的多功能丝的动物。澳大利亚联邦工业与科技研究所昆虫学系的塔拉·萨瑟兰博士和她的科研组,正在寻找由其他昆虫吐丝的方法,他们的研究结果发表在最近的《分子生物学与进化》(Molecular Biology and Evolution)杂志上,  相似文献   

2.
泌蜡昆虫体表除了具有和其他昆虫一样的薄蜡层之外,还具有特殊的蜡腺,在生长发育过程中能够分泌蜡质覆盖于体表,从而有利于昆虫防止体内水分过度蒸发、抵御外界多种不利条件、阻碍病原物入侵和躲避天敌寄生或捕食,对昆虫的生存和繁衍具有重要的保护作用。本文概述了蚧虫、蚜虫、蜡蝉、木虱、粉虱和粉蛉等6类常见泌蜡昆虫的蜡腺和蜡泌物的超微形态结构、蜡泌物的主要化学组成及泌蜡的分子机制等方面的研究进展,以期为今后其在昆虫分类学和系统发育学的研究以及在害虫防治中的应用提供参考。  相似文献   

3.
婆罗洲丝蚁的耐寒性   总被引:1,自引:0,他引:1  
纺足目昆虫是分布于热带和亚热带温暖地区的昆虫,这类昆虫在我国分布较少。1978年美国昆虫学家Ross将我国至今已记载的纺足目昆虫种类鉴定为4种,其中婆罗洲丝蚁Apothonia borne(?)sis(Hagen)是广东、广西最常见的种类之一。此虫是根据在婆罗洲(加里曼丹)采集的标本定名,因此它的分布从热带一直到我国的南方。据在广东的初步调查,它的分布愈向北愈少。关于它的分布北界现在还不清楚,冬季低温对它的活动和生存的影响也不知  相似文献   

4.
家蚕后丝腺细胞染色质的一些特性   总被引:1,自引:0,他引:1  
在家蚕幼虫发育阶段,丝腺细胞的大小和脱氧核糖核酸(DNA)的含量均有巨大增长,而没有细胞分裂发生,这种DNA含量的增加是由于细胞内整个染色体组型多次全部复制的结果,因此称之为多倍化现象。细胞染色体组型的多倍化现象,也在其他生物种类中存在,可是同丝腺细胞比起来可以说是相差很大。后丝腺和中丝腺每个细胞所含DNA最高量大约是体细胞的20—100万倍。这是与它们制造和分泌大量丝蛋白相一致的。后丝腺细胞是合成丝腺的核心——丝心蛋白的主要部位。为了阐明昆虫激素是如何调节和控制丝心蛋白的合成,需要分离出一定纯度的后丝腺细胞染色质来。后丝腺细胞体积大、细胞核呈树枝状使分离工作困难。我们在这方面作了一个尝试,结果报道如下:  相似文献   

5.
【目的】梧桐木虱Carsidara limbata是一种严重危害梧桐Firmiana simplex的害虫,观察并明确若虫蜡泌物及不同虫龄泌蜡腺体超微形态特征,有助于为其生长发育的相关研究提供理论依据。【方法】本研究依据梧桐木虱若虫形态特征变化划分样本虫龄,使用体视显微镜和扫描电镜(SEM)观察若虫蜡泌物及不同虫龄泌蜡腺体的超微形态结构特征。【结果】结果表明,梧桐木虱若虫泌蜡腺体主要分为两类:一类为泌蜡小孔,3-5龄若虫体壁出现此结构;另一类为规则或不规则圆形多孔蜡腺孔,该结构1龄若虫极少或无,其他虫龄均有分布。低龄若虫孔腺数目和类型较老龄少。若虫蜡泌物分为4种类型,即丝状蜡丝、空心"C"形蜡丝、弹簧状蜡丝、空心长蜡丝。此外,腹部末端有环肛孔环结构,腹部背腹面遍布微刺及各类刚毛。【结论】梧桐木虱若虫有4类蜡泌物和2类泌蜡腺体,随虫龄不同其类型和分布存在差异。本研究为裂木虱科害虫泌蜡器官的研究提供了参考依据。  相似文献   

6.
<正> 已有几千年饲养历史的家蚕(Bomoyx mori)、柞蚕(Antherea Pernyi)和近几十年才开发利用的蓖麻蚕(Philosamia cinthia ricini)、天蚕(Antherea yamamai)等均为具有很高经济价值的泌丝昆虫。本文就这四种蚕的卵壳蛋白氨基酸组成进行了分析比较,在理论上为进一步探讨蚕  相似文献   

7.
足丝蚁     
<正> 纺足目(Embioptera)的足丝蚁,是人们不大注意而广泛分布于热带和亚热带的一类昆虫。我国南方省(区)也有分布。足丝蚁的形态、生理、生态等,富有探索和研究的价值,又易于在实验室里培育,为此,根据作者的工作并结合国外资料整理介绍如下。 形态 足丝蚁体长4—6毫米,体色浅褐至深褐,表皮软而薄;复眼雄的较大,雌的较小;缺单眼。触角念珠状,由15—32节组成;口器咀嚼式,雄虫上颚发达(图1:5)。前胸较头部为狭,雄  相似文献   

8.
中间丝     
自60年代后期,陆续发现了直径约8—10nm的细胞质丝。最初由于对这类纤丝的性质不清楚,曾有fila-ments、intermediate filaments、β-filaments、80-100 filaments、100(10nm)filaments诸多命名。至70年代后期才逐渐统一为intermediate filaments(IF)或100A(10nm)filaments。IF的中文名亦很纷繁,如中等纤维、中间纤维、居间纤维、中间丝等。 IF的直径介于肌动蛋白丝与肌球蛋白丝(粗丝)和微管之间,命名冠以“中间”修饰词是恰当的。与微管相对而言,IF、微丝和粗丝同属纤丝filaments范畴。既然microfilaments和thick filaments分别称为微丝和粗丝,那么IF则理应称为中间丝。  相似文献   

9.
采用扫描电镜技术研究了柿白毡蚧Asiacornococcus kaki(Kuwana)泌蜡腺体、蜡泌物的超微结构与蜡壳形成过程.结果发现,蜡壳形成分3个阶段,即泌蜡发生期、泌蜡增长期和蜡囊形成期,由3种腺体分泌的蜡质构成.锥刺是泌蜡的主要器官,其分泌的粗蜡管形成蜡壳的框架.管腺分泌空心细蜡丝,与框架蜡管紧密交织在一起.单孔腺分泌的细小蜡丝散布虫体表面.雄茧扁平,由空心长丝状蜡编织形成.  相似文献   

10.
由酵母菌引起的昆虫真菌病原很少,尤其是用来防治农业上的重要害虫——粘虫的酵母菌至今未见报道。本文报道粘虫病原物——纤细假丝酵母菌的分离、纯化和毒力测定。  相似文献   

11.
Many spiders use silk to construct webs that must function for days at a time, whereas many other species renew their webs daily. The mechanical properties of spider silk can change after spinning under environmental stress, which could influence web function. We hypothesize that spiders spinning longer‐lasting webs produce silks composed of proteins that are more resistant to environmental stresses. The major ampullate (MA) silks of orb web spiders are principally composed of a combination of two proteins (spidroins) called MaSp1 and MaSp2. We expected spider MA silks dominated by MaSp1 to have the greatest resistance to post‐spin property change because they have high concentrations of stable crystalline β‐sheets. Some orb web spiders that spin three‐dimensional orb webs, such as Cyrtophora, have MA silks that are predominantly composed of MaSp1. Hence, we expected that the construction of three‐dimensional orb webs might also coincide with MA silk resistance to post‐spin property change. Alternatively, the degree of post‐spin mechanical property changes in different spider silks may be explained by factors within the spider's ecosystem, such as exposure to solar radiation. We exposed the MA silks of ten spider species from five genera (Nephila, Cyclosa, Leucauge, Cyrtophora, and Argiope) to ecologically high temperatures and low humidity for 4 weeks, and compared the mechanical properties of these silks with unexposed silks. Using species pairs enabled us to assess the influence of web dimensionality and MaSp composition both with and without phylogenetic influences being accounted for. We found neither the MaSp composition nor the three‐dimensionality of the orb web to be associated with the degree of post‐spin mechanical property changes in MA silk. The MA silks in Leucauge spp. are dominated by MaSp2, which we found to have the least resistance to post‐spin property change. The MA silk in Argiope spp. is also dominated by MaSp2, but has high resistance to post‐spin property change. The ancestry of Argiope is unresolved, but it is largely a tropical genus inhabiting hot, open regions that present similar stressors to silk as those of our experiment. Ecological factors thus appear to influence the vulnerability of orb web spider MA silks to post‐spin property change. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 580–588.  相似文献   

12.
蜘蛛丝作为一种具有优良机械性能的天然动物蛋白纤维,其特有的结构和机械性能与其生物学功能密切相关。由大壶状腺纺出的拖牵丝在蜘蛛的行走、建网、捕食、逃生、繁殖等多种生命活动中均发挥了重要的功能,其机械性能会受到多种内外因素相互作用的影响。本文对在不同体重、不同猎物饲养和不同营养状态3种条件下人工抽出的悦目金蛛(Argiope amoena)拖牵丝与其不同单丝间的力学性能进行了比较研究。结果表明,悦目金蛛拖牵丝的力学性能在组间、组内不同个体,以及同一个体不同丝纤维间变异都较大。随着蜘蛛个体的增大,蛛丝横截面直径逐渐增大,这会使得蛛丝的力学性能更好,便于作为救命索的拖牵丝在遇到危险时承受蜘蛛体重;蜘蛛在经过1个月的饥饿后,蛛丝在屈服点附近的力学性能并未发生显著变化,而断裂点应变和断裂能均显著减小,同时也表明无论对于作为救命索还是网丝,拖牵丝的弹性形变性能在与蛛丝相关的微观进化中要优先于塑性形变。这是蜘蛛在能量摄入受到限制时对拖牵丝的投入权衡的结果。  相似文献   

13.
Conservation of essential design features in coiled coil silks   总被引:1,自引:0,他引:1  
Silks are strong protein fibers produced by a broad array of spiders and insects. The vast majority of known silks are large, repetitive proteins assembled into extended beta-sheet structures. Honeybees, however, have found a radically different evolutionary solution to the need for a building material. The 4 fibrous proteins of honeybee silk are small ( approximately 30 kDa each) and nonrepetitive and adopt a coiled coil structure. We examined silks from the 3 superfamilies of the Aculeata (Hymenoptera: Apocrita) by infrared spectroscopy and found coiled coil structure in bees (Apoidea) and in ants (Vespoidea) but not in parasitic wasps of the Chrysidoidea. We subsequently identified and sequenced the silk genes of bumblebees, bulldog ants, and weaver ants and compared these with honeybee silk genes. Each species produced orthologues of the 4 small fibroin proteins identified in honeybee silk. Each fibroin contained a continuous predicted coiled coil region of around 210 residues, flanked by 23-160 residue length N- and C-termini. The cores of the coiled coils were unusually rich in alanine. There was extensive sequence divergence among the bee and ant silk genes (<50% similarity between the alignable regions of bee and ant sequences), consistent with constant and equivalent divergence since the bee/ant split (estimated to be 155 Myr). Despite a high background level of sequence diversity, we have identified conserved design elements that we propose are essential to the assembly and function of coiled coil silks.  相似文献   

14.
Spiders can produce up to seven different types of silks or glues with different mechanical properties. Of these, flagelliform (Flag) silk is the most elastic, and aciniform (AcSp1) silk is the toughest. To produce a chimeric spider silk (spidroin) FlagR-AcSp1R, we fused one repetitive module of flagelliform silk from Araneus ventricosus and one repetitive module of aciniform silk from Argiope trifasciata. The recombinant protein expressed in E. coli formed silk-like fibers by manual-drawing. CD analysis showed that the secondary structure of FlagR-AcSp1R spidroin remained stable during the gradual reduction of pH from 7.0 to 5.5. The spectrum of FTIR indicated that the secondary structure of FlagR-AcSp1R changed from α-helix to β-sheet. The conformation change of FlagR-AcSp1R was similar to other spidroins in the fiber formation process. SEM analysis revealed that the mean diameter of the fibers was around 1 ~ 2 μm, and the surface was smooth and uniform. The chimeric fibers exhibited superior toughness (~33.1 MJ/m3) and tensile strength (~261.4 MPa). This study provides new insight into design of chimeric spider silks with high mechanical properties.  相似文献   

15.
蜘蛛丝蛋白研究进展   总被引:4,自引:0,他引:4  
由于蜘蛛丝蛋白分子高度重复的一级结构、特殊的溶解特性和分子折叠行为以及具有形成非凡力学特性丝纤维的能力而引人注目。本文从蛛丝蛋白基因、天然蛛丝形成过程、蛛丝蛋白的基因工程生产及蛛丝蛋白的应用前景等几个方面着重介绍了近20年来对蛛丝蛋白的研究进展。围绕蛛丝蛋白展开的研究将有助于揭示蛋白质一级结构、蛋白质分子折叠与蛋白质大分子特性之间的内在联系。  相似文献   

16.
The mechanical properties of spider silks have diverged as spiders have diversely speciated. Because the main components of silks are proteins, it is valuable to investigate their sequences. However, silk sequences have been regarded as difficult information to analyze due to their imbalance and imperfect tandem repeats (ITR). Here, an in silico approach is applied to systemically analyze a group of silk sequences. It is found that every time new spider groups emerge, unique trimer motifs appear. These trimer motifs are used to find additional clues of evolution and to determine relationships with mechanical properties. For the first time, crucial evidence is provided that shows silk sequences coevolved with spider species and the mechanical properties of their fibers to adapt to new living environments. This novel approach can be used as a platform for analyzing other groups of ITR‐harboring proteins and to obtain information for the design of tailor‐made fibrous protein materials.  相似文献   

17.
Silk threads from spiders exhibit extraordinary mechanical properties, such as superior toughness and elasticity. Spider silks consist of several different large repetitive proteins that act as the basic materials responsible for these outstanding features. The production of spider silk protein variants in plants opens up new horizons in the production and functional investigation that enable the use of spider silks in innovative material development, nanotechnology and biomedicine in the future. This review summarizes and discusses production of spider silk protein variants in plants, especially with regards to plant expression systems, purification strategies, and characteristics of spider silk variants. Furthermore, the challenge of producing native-sized recombinant spidroins in planta is outlined, presenting three different strategies for achieving these high repetitive proteins with the help of non-repetitive C-terminal domains, crosslinking transglutaminase, and self-linking inteins. The potential of these fascinating proteins in medicine is also highlighted.  相似文献   

18.
Silk has been used for centuries in the textile industry and as surgical sutures. In addition to its unique mechanical properties, silk possesses other properties, such as biocompatibility, biodegradability and ability to self-assemble, which make it an interesting material for biomedical applications. Although silk forms only fibers in nature, synthetic techniques can be used to control the processing of silk into different morphologies, such as scaffolds, films, hydrogels, microcapsules, and micro- and nanospheres. Moreover, the biotechnological production of silk proteins broadens the potential applications of silk. Synthetic silk genes have been designed. Genetic engineering enables modification of silk properties or the construction of a hybrid silk. Bioengineered hybrid silks consist of a silk sequence that self-assembles into the desired morphological structure and the sequence of a polypeptide that confers a function to the silk biomaterial. The functional domains can comprise binding sites for receptors, enzymes, drugs, metals or sugars, among others. Here, we review the current status of potential applications of silk biomaterials in the field of oncology with a focus on the generation of implantable, injectable and targeted drug delivery systems and the three-dimensional cancer models based on silk scaffolds for cancer research. However, the systems described could be applied in many biomedical fields.  相似文献   

19.
Insect silks have been used by mankind for millennia to produce textiles and in particular, the cocoon silk of Bombyx mori was the base of one of the most important industries in history. In fact, B. mori is probably the only domesticated insect if not invertebrate in its true and strict sense, comparable to cattle and other livestock that humans have known and bred since the Neolithic period. In contrast, reports regarding the use of spider silk throughout history have the character of travellers’ tales or anecdotes, and serious attempts to exploit these biomaterials on a large scale have not been undertaken until recently. Indeed, the cannibalism of these carnivores makes their farming difficult and the production of significant yields of spider silk virtually impossible. Only today, with recombinant technologies available, does this problem seem to have been overcome. But why use spider silk at all – if we have the infrastructure to produce significant yields of silk from Bombyx? In contrast to most insects, spiders do not spin from labial glands, and many spiders possess different types of gland, most of them active throughout the whole lifespan. Typical orb‐weavers (Araneoidea) for instance possess up to seven different types of silk gland to produce different silk fibers and glues. Each of these products has evolved for a particular use and the respective material properties are highly adapted to that use. As the group of Araneae is about 400 million years old, the oldest fossil orb‐weaver is dated about 150 million years, and the use of silk is crucial to a spider's survival, we can expect that evolution will have “squeezed out every iota” to achieve optimum performance at minimum cost. Indeed, some dragline silks such as the major ampullate silks of some Nephila species show amazing mechanical properties that, in terms of toughness, are far superior to Bombyx silk. Labels like “stronger than steel” or “even better than Kevlar” were attached to them, and the Canadian‐based biotech company Nexia created the trademark “bio‐steel” for their prospective product. The discovery of these exceptional mechanical properties of those protein fibers triggered intense research on spider silk, with the goal of their commercial exploitation. But there is more to Arachne's weave and science is beginning to pick up those threads.  相似文献   

20.
Huang W  Lin Z  Sin YM  Li D  Gong Z  Yang D 《Biochimie》2006,88(7):849-858
Spider silks are renowned for their excellent mechanical properties. Although several spider fibroin genes, mainly from dragline and capture silks, have been identified, there are still many members in the spider fibroin gene family remain uncharacterized. In this study, a novel silk cDNA clone from the golden web spider Nephila antipodiana was isolated. It is serine rich and contains two almost identical fragments with one varied gap region and one conserved spider fibroin-like C-terminal domain. Both in situ hybridization and immunoblot analyses have shown that it is specifically expressed in the tubuliform gland. Thus, it likely encodes the silk fibroin from the tubuliform gland, which supplies the main component of the inner egg case. Unlike other silk proteins, the protein encoded by the novel cDNA in water solution exhibits the characteristic of an alpha-helical protein, which implies the distinct property of the egg case silk, though the fiber of tubuliform silk is mainly composed of beta-sheet structure. Its sequence information facilitates elucidation of the evolutionary history of the araneoid fibroin genes.  相似文献   

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