大腹园蛛拖丝蛋白一级结构初步研究

采用部分酸水解的方法对大腹园蛛（Ａｒａｎｅｕｓｖｅｎｔｒｏｃｏｓｕｓ）拖丝纤维蛋白进行水解,通过反相高液相色谱分离到一些重复小肽片段,对其序列分析表明,该蜘蛛拖丝蛋白与肖蛸科的棒络新妇蛛（Ｎｅｐｈｉｌａｃｌａｖｉｐｅｓ）丝蛋白的序列比较,有一个完全相同的肽段ＧＹＧＰＧ,其余所测片段测存在差异,显示不同种属的蜘蛛丝在一级结构上的同异,并探讨了结构和功能的关系。     

我国南方捕鸟蛛一新种的生物化学鉴定(蜘蛛目,捕鸟蛛科)

采用高效液相色谱（ＨＰＬＣ）、激光解析基质辅助电离飞行时间质谱（ＭＡＩＤＩ－ＴＯＦＭＳ）和蛋白质序列分析方法,对从我国海南通什地区发现的一种捕鸟蛛与广西虎纹捕鸟蛛（Ｓｅｌｅｎｏｃｏｓｍ ｉａｈｕｗ ｅｎａ）的毒液进行了比较分析． 虽然两种蜘蛛形态十分相似,但其毒液的化学组成和主要毒素的氨基酸序列存在明显的差异,说明两种蜘蛛在进化上有同源性但分化很早．应列为不同种,特将海南发现的蜘蛛新种定名为海南捕鸟蛛,新种Ｓｅｌｅｎｏｃｏｓｍ ｉａ ｈａｉｎａｎａ ｓｐ．ｎｏｖ．     

宁南山区灌溉农业立体复合种植生态系统生产力的研究

宁南山区灌溉农业立体复合种植生态系统生产力的研究杜守宇田恩平,王占山（宁夏农业技术推广总站,银川７５０００１）（固原县农业技术推广中心,７５６０００）ＳｔｕｄｙｏｎＰｒｏｄｕｃｔｉｖｉｔｙｏｆＩｒｒｉｇａｔｅｄＳｔｅｒｅｏｓｃｏｐｉｃＭｕｌｔｉｐｌｅ－ＣｒｏｐｐｉｎｇＥｃｏｓｙｓｔｅｍｓｉｎＭｏｕｎｔａｉｎｏｕｓＡｒｅａｏｆＳｏｕｔｈｅｒｎＮｉｎｇｘｉａ￥ＤｕＳｈｏｕｙｕ（ＣｅｌｌｅｒａｌＳｔａｔｉｏｎｏｆＡｇｒｉｃｕｌｔｕｒａｌＴｅｃｈｎｉｑｕｅＥｘｔｅｎｓｉｏｎｏｆＮｉｎｇｘｉａ,Ｙｉｎｃｈｕａｎ７５０００１）,ＴｉａｎＥｎｐｉｎｇ,ＷａｎｇＺｈａｎｓｈａｎ（ＡｇｒｉｃｕｌｔｕｒａｌＴｅｃｈｎｉｑｕｅＥｘｔｅｎｓｉｏｎＣｅｎｔｅｒｏｆＣｕｙｕａｎｃｏｕｎｔｙ,７５６０００）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３．１２（６）：１１－１６．ＴｈｅｖａｒｉｏｕｓｃｒｏｐｐｉｎｇｅｃｏｓｙｓｔｅｍｓａｒｅａｓｓｅｓｓｅｄｃｏｍｐｒｅｈｅｎｓｉｖｅｌｙｆｏｒｂｅｎｅｆｉｔｂｙｔｈｅａｎａｌｙｓｉｓｏｆＨｉｅｒａｒｃｈｉｃａｌｐｒｏｃｅｄｕｒｅａｎｄｔｈｅｅｘｐｅｃｔｅｄｂｅｎｅｆｉｃｉａｌｖａ     

中国南方低丘红壤区人工复合生态系统模式建造研究

中国南方低丘红壤区人工复合生态系统模式建造研究徐盛荣,吴珊眉,李辉信（南京农业大学土壤农业化学系,２１００１４）ＭｏｄｅｌｉｎｇｏｆＡｒｔｉｆｉｃｉａｌＣｏｍｐｌｅｘＥｃｏｓｙｓｔｅｍｉｎＬｏｗ－ｈｉｌｌｙＲｅｄＳｏｉｌＲｅｇｉｏｎｏｆＳｏｕｔｈＣｂｉｎａ￥．ＸｕＳｈｅｎｇｒｏｎｇ;ＷｕＳｈａｎｍｅｉ;ＬｉＨｕｉｘｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＳｏｉｌＳｃｉｅｎｃｅａｎｄＡｇｒｉｃｕｌｔｕｒａｌＣｈｅｍｉｓｔｒｙ,ＮａｎｊｉｎｇＡｇｒｉｃｕｌｔｕｒａｌＵｎｉｖｅｒｓｉｔｙ）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（２）：３９—４０．Ｔｈｉｓｐａｐｅｒｒｅｓｅａｒｃｈｅｓｉｎｔｏｔｈｅｍｏｄｅｌｉｎｇｏｆａｒｔｉｆｉｃｉａｌｃｏｍｐｌｅｘｅｃｏｓｙｓｔｅｍｉｎｃｏｒｐｏｒａｔｉｎｇｃｒｏｐ,ｆｒｕｉｔ,ｆｏｒｅｓｔａｎｄａｎｉｍａｌｈｕｓｂａｎｄｒｙｗｉｔｈｉｎａｃａｔｃｈｍｅｎｔａｒｅａ,ｗｈｉｃｈｉｓａｂａｓｉｃｕｎｉｔｏｆｌｏｗｈｉｌｌｙｒｅｇｉｏｎｉｎｓｏｕｔｈＣｈｉｎａ．Ｔｈｅｍｏｄｅｌｐｒｏｄｕｃｅｓｓｉｇｎｉｆｉｃａｎｔａｎｄｃｏｍｐｒｅｈｅｎｓｉｖｅｐｒｏｆｉｔｓ．Ｆｉ     

中国尖腹蛛属一新种记述：蜘蛛目：园蛛科

本文记述分布于我国陕西太白山的园蛛科Ａｒａｎｅｉｄａｅ尖腹蛛属Ａｃｕｌｅｐｅｒｉａ一新种,太白尖腹蛛Ａｃｕｌｅｐｅｒｉａｔａｉｂａｉｓｈａｎｅｎｓｉｓｓｐ．ｎｏｖ．,模式标本分别保存河北教育学院和西安师范学院。     

中国尾孢菌属及其近似属的研究VI.(英文)

本文报道９种尾孢菌,其中有２个新种：蟹甲草尾孢 Ｃｅｒｃｏｓｐｏｒａ ｃａｃａｌｉａｅ Ｙ． Ｌ． Ｇｕｏ　＆ Ｙ．Ｊｉａｎｇ和菜蓟尾孢Ｃｅｒｃｏｓｐｏｒａ 　ｃｙｎａｒａｅ Ｙ． Ｌ． Ｇｕｏ　＆ Ｙ． Ｊｉａｎｇ,中国新记录种有迪氏尾孢Ｃｅｒｃｏｓｐｏｒａｄｅｍｅｔｒｉｏｎｉａｎａ　 Ｇ． Ｗｉｎｔｅｒ,田菁生尾孢 Ｃｅｒｃｏｓｐｏｒａ　 ｇｌｏｔｈｉｄｉｉｃｏｌａ 　Ｔｒａｃｙ　＆ 　Ｅａｒｌｅ,甘草尾孢 Ｃｅｒｃｏｓｐｏｒａｇｌｙｃｙｒｒｈｉｚａｅ 　（Ｓａｖｕｌｅｓｃｕ　＆　Ｓａｎｄｕ）Ｃｈｕｐｐ,野桐尾孢Ｃｅｒｃｏｓｐｏｒａ　ｍａｌｌｏｔｉ　Ｅｌｌｉｓ　＆ 　Ｅｖｓｒｈ,木薯尾孢Ｃｅｒｃｏｓｐｏｒａ ｍａｎｉｈｏｂａｅ Ｖｉｅｇａｓ,补骨脂尾孢 Ｃｅｒｃｏｓｐｏｒａ ｐｓｏｒａｌｅａｅ－ｂｉｔｕｍｉｎｏｓａｅ Ｓａｖｕｌ．＆ Ｓａｎｄｕ和香豆尾孢Ｃｅｒｃｏｓｐｏｒａ ｔｒａｖｅｒｓｉａｎａ Ｓａｃｃ。文中为新种提供了拉丁文描述并附图,研究的标本保存在中国科学院微生物研究所菌物标本馆（ＨＭＡＳ）。     

浸润垄作稻田土壤生态系统的研究

浸润垄作稻田土壤生态系统的研究魏朝富,高明,车福才,邓春（西南农业大学土化系重庆６３０７１６）ＡＳｔｕｄｙｏｎＩｎｆｉｌｔｒａｔｅｄ－ＲｉｄｇｅｄＰａｄｄｙＳｏｉｌＥｃｏｓｙｓｔｅｍ￥．ＷｅｉＣｈａｏｆｕ;ＧａｏＭｉｎｇ,ＣｈｅＦｕｃｈａｉ;ＤｅｎｇＣｈｕｎ（ＳｏｕｔｈｗｅｓｔＡｇｒｉｃｕｌｌｕｒａｌＵｎｉｖｅｒｓｉｔｙ,）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（３）：２６－３０;Ｔｈｉｓｐａｐｅｒｄｅａｌｓｗｉｃｈａｎｉｎｆｉｌｔｒａｔｅｄ－ｒｉｄｇｅｄｐａｄｄｙｓｏｉｌｅｃｏｓｙｓｔｅｍｗｈｉｃｈｉｓｃｏｎｓｔｒｕｃｔｅｄｂｙｒｉｄｇｉｎｇａｎｄｃｏｎ－ｔｉｎｕｏｕｓｆｕｒｒｏｗｉｎｆｉＩｔｒａｔｉＯｎｉｒｒｉｇａｔｉｏｎ,ＣｏｍｐａｒｉｎｇｗｉｔｈｌｅｖｅｌｉｎｆｉＩｔｒａｔｅｄｐａｄｄｙｓｏｉｌｅｃｏｓｙｓｔｅｍ,ｔｈｉｓｅｃｏｓｙｓ－ｔｅｍｈａｓｃｏｅｘｉｓｔｅｄｇａｓ－ｌｉｑｕｉｄ,ｇａｓ－ｓｏｌｉｄａｎｄｌｉｑｕｉｄ－ｓｏｌｉｄｉｎｔｅｒｆａｃｅｓ,ｅｎｌａｒｇｅｓｓｏｉｌｓｕｒｆａｃｅｂｙ３８％ａｎｄｉｎｃｒｅａｓｅｓｃｕＩｔｉｖａｔｅｄｌａｙｅｒｂｙ５－１０ｃｍ．     

辽西走廊农业生态系统区位优势分析

辽西走廊农业生态系统区位优势分析梁文举（中国科学院沈阳应用生态研究所,１１００１５）ＬｏｃａｔｉｏｎａｌＳｕｐｅｒｉｏｒｉｔｙＡｎａｌｙｓｉｓｏｆＡｇｒｏｅｃｏｓｙｓｔｅｍｓｉｎＷｅｓｔＬｉａｏｎｉｎｇＣｏｒｒｉｄｏｒ￥ＬｉａｎｇＷｅｎｊｕ（ＩｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉｅｄＥｃｏｌｏｇｙ,ＡｃａｄｅｍｉａＳｉｎｉｃａ,Ｓｈｅｎｙａｎｇ１１００１５）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（２）：５９－６０．Ｂａｓｅｄｏｎｔｈｅｒｅｌａｔｉｖｅａｇｇｒｅｇａｔｉｏｎｄｅｇｒｅｅｓａｍｏｎｇｈｉｅｒａｒｃｈｉｅｓｏｆｄｉｆｆｅｒｅｎｔａｇｒｏｅｃｏｓｙｓｔｅｍｓ,ｔｈｅａｕｔｈｏｒｐｒｏ－ｐｏｓｅｄｔｈａｔｌｏｃａｔｉｏｎａｌｑｕｏｔｉｅｎｔｍｏｄｅｌｃｏｕｌｄｂｅｕｓｅｄｔｏｍｅａｓｕｒｅｔｈｅｌｏｃａｔｉｏｎａｌｓｕｐｅｒｉｏｒｉｔｙｏｆａｇｒｏｅｃｏｓｙｓｔｅｍ．Ｔｈｅｍａｉｎｐｕｒｐｏｓｅｏｆｔｈｉｓｐａｐｅｒｉｓｔｏｐｒｏｖｉｄｅａｓｃｉｅｎｔｉｆｉｃｂａｓｉｓｆｏｒｃｈｏｏｓｉｎｇａｇｒｉｃｕｌｔｕｒａｌｍａｒｋｅｔａｂｌｅｂａｓｅｓａｎｄｅｓｔａｂｌｉｓｈｉｎｇａｈｉｇ     

长江流域农业生态研究现状与展望

长江流域农业生态研究现状与展望徐琪（中国科学院南京土壤研究所,２１０００８）ＣｕｒｒｅｎｔＳｉｔｕａｔｉｏｎａｎｄＰｒｏｓｐｅｃｔｏｆＡｇｒｏ－ｅｃｏｓｙｓｔｅｍＲｅｓｅａｒｃｈｉｎｔｈｅＹａｎｇｔｚｅＲｉｖｅｒＢａｓｉｎ．￥ＸｕＱｉ（ＩｎｓｔｉｔｕｔｅｏｆＳｏｉｌＳｃｉｅｎｃｅ,ＡｃａｄｅｍｉａＳｉｎｉｃａ,Ｎａｎｊｉｎｇ２１０００８）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｒ,１９９３,１２（２）：２５－２６．Ｔｈｅｃｕｒｒｅｎｔｓｉｔｕａｔｉｏｎｏｆａｇｒｏ－ｅｃｏｓｙｓｔｅｍｒｅｓｅａｒｃｈｉｎｔｈｅＹａｎｇｔｚｅＲｉｖｅｒｂａｓｉｎａｒｅｂｒｉｅｆｌｙｉｎｔｒｏｄｕｃｅｄａｎｄｔｈｅｆｕｒｔｈｅｒｍａｉｎｒｅｓｅａｒｃｈｆｉｅｌｄｓａｒｅｐｒｏｐｏｓｅｄｆｒｏｍｔｈｅｖｉｅｗｏｆａｇｒｉｃｕｌｔｕｒａｌｓｕｓｔａｉｎａｂｉｌｉｔｙ．Ｋｅｙｗｏｒｄｓ：ａｇｒｏｅｃｏｓｙｓｔｅｍ,ＹａｎｇｔｚｅＲｉｖｅｒｂａｓｉｎ,ａｇｒｉｃｕｌｔｕｒａｌｓｕｓｔａｉｎａｂｉｌｉｔｙ．１土地资源概况长江流域既是古老农业地区,也具有丰富的土地资源类型,为大农业发展提供了广阔的前景。在生态农业建设中典型甚多,并正在     

应用生态学报第5卷（1994）关键词索引

应用生态学报第５卷（１９９４）关键词索引ＣＨＩＮＥＳＥＪＯＵＲＮＡＬＯＦＡＰＰＬＩＥＤＥＣＯＬＯＧＹＶｏｌ．５（１９９４）ＫＥＹＷＯＲＤＩＮＤＥＸＡＡｃａｎｔｈｏｐａｎａｘｓｅｎｌｉｃｏｓｕｓｉｇｌｏｏ５（３）：２３７Ａｇｒｏｅｃｏｓｙｓｔｅｍ￥ｋ４...     

大腹园蛛丝腺的氨基酸组成分析

通过解剖大腹园蛛,获得５种丝腺体,并对各丝腺蛋白进行了氨基酸组成分析和蛋白质相对分子质量测定,比较了不同丝腺体蛋白质组成的差异,发现不同丝腺体蛋白质氨基酸组成中Ｇｌｙ和Ｇｌｕ均有较高含量,而Ｓｅｒ的含量并不高,壶状腺中含有较高的Ｐｒｏ,而管状腺中含有较高的Ａｒｇ．同时发现不同丝腺体蛋白质的相对分子质量存在较明显差异,例如集合腺中不同相对分子质量的蛋白质分布较均匀,而在葡萄状腺中大分子质量的蛋白质明显高于小分子质量蛋白质．     

Evidence for diet effects on the composition of silk proteins produced by spiders

Silks are highly expressed, secreted proteins that represent a substantial metabolic cost to the insects and spiders that produce them. Female spiders in the superfamily Araneoidea (the orb-spinning spiders and their close relatives) spin six different kinds of silk (three fibroins and three fibrous protein glues) that differ in amino acid content and protein structure. In addition to this diversity in silks produced by different glands, we found that individual spiders of the same species can spin dragline silks (drawn from the spider's ampullate gland) that vary in content as well. Freely foraging ARGIOPE: argentata (Araneae: Araneoidea), collected from 13 Caribbean islands, produced dragline silk that showed an inverse relationship between the amount of serine and glycine they contained. X-ray microdiffraction of the silks localized these differences to the amorphous regions of the protein that are thought to lend silks their elasticity. The crystalline regions of the proteins, which lend silks their strength, were unaffected. Laboratory experiments with ARGIOPE: keyserlingi suggested that variation in silk composition reflects the type of prey the spiders were fed but not the total amount of prey they received. Hence, it may be that the amino acid content (and perhaps the mechanical properties) of dragline silk spun by ARGIOPE: directly reflect the spiders' diet. The ability to vary silk composition and, possibly, function is particularly important for organisms that disperse broadly, such as Argiope, and that occupy diverse habitats with diverse populations of prey.     

摩鹿加云斑蛛卵袋结构与纤维组成

采用扫描电子显微镜（SEM）和氨基酸自动分析仪对摩鹿加云斑蛛Cyrtophora moluccensis卵袋的结构和组成进行了观察研究.结果表明摩鹿加云斑蛛的卵袋呈椭球状,是由多种丝腺纺出的微米与纳米级的丝纤维形成的多个覆盖层构成的,包括白色框架、军绿色与灰白色外覆盖层和白色内覆盖层3部分.卵袋框丝与典型的拖牵丝氨酸组成基本相似,丙氨酸和甘氨酸的含量最丰富,分别约占39%和33%,其次是谷氨酸、丝氨酸和脯氨酸,分别约占7.8%、5.7%和3.6%;其余卵袋丝纤维的氨基酸组成与典型的柱状腺丝相似,与卵袋框丝相比,卵袋覆盖层的丝氨基酸的含量显著增加,约占21%,同时甘氨酸和脯氨酸的含量显著减少,分别约占12%和1%,并含有更多的极性和大侧链氨基酸,其丙氨酸的含量变化不大,仍占了27%左右.根据氨基酸组成与扫描电镜的结果综合分析了不同自径丝纤维的丝腺来源.     

Isolation of a clone encoding a second dragline silk fibroin. Nephila clavipes dragline silk is a two-protein fiber.

Spider dragline silk is a unique protein fiber possessing both high tensile strength and high elasticity. A partial cDNA clone for one dragline silk protein (Spidroin 1) was previously isolated. However, the predicted amino acid sequence could not account for the amino acid composition of dragline silk. We have isolated a partial cDNA clone for another dragline silk protein (Spidroin 2), demonstrating that dragline silk is composed of multiple proteins. The amino acid sequence exhibits an entirely different repetitive motif than Spidroin 1. Spidroin 2 is predicted to consist of linked beta-turns in proline-rich regions which alternate with beta-sheet regions composed of polyalanine segments. This structure for Spidroin 2 provides a model for dragline silk structure and function.     

横纹金蛛卵袋结构与纤维组成

采用SEM和氨基酸自动分析仪对横纹金蛛(Argiope bruennichi)卵袋的超微结构与氨基酸组成进行了观察研究.结果表明,横纹金蛛卵袋呈封闭的葫形,是由多种丝腺纺出的微米与纳米级的丝纤维形成的多个覆盖层构成,具有多层复杂结构,从外向内分别为:框架、卵袋覆盖帽、外覆盖层和内覆盖层、卵块覆盖帽、卵块包裹层,其中外覆...     

Identification of four major hornet silk genes with a complex of alanine-rich and serine-rich sequences in Vespa simillima xanthoptera Cameron

Hornet silk, a fibrous protein in the cocoon produced by the larva of the vespa, is composed of four major proteins. In this study, we constructed silk-gland cDNA libraries from larvae of the hornet Vespa simillima xanthoptera Cameron and deduced the full amino acid sequences of the four hornet silk proteins, which were named Vssilk 1-4 in increasing order of molecular size. Portions of the amino acid sequences of the four proteins were confirmed by Matrix-assisted laser desorption/ionization-time of flight/mass spectrometry (MALDI-TOF/MS) and N-terminal protein sequencing. The primary sequences of the four Vssilk proteins (1-4) were highly divergent, but the four proteins had some common properties: (i) the amino acid compositions of all four proteins were similar to each other in that the well-defined and characteristic repetitive patterns present in most of the known silk proteins were absent; and (ii) the characteristics of the amino acid sequences of the four proteins were also similar in that Ser-rich structures such as sericin were localized at both ends of the chains and Ala-rich structures such as fibroin were found in the center. These characteristic primary structures might be responsible for the coexisting alpha-helix and beta-sheet conformations that make up the unique secondary structure of hornet silk proteins in the native state. Because heptad repeat sequences of hydrophobic residue are present in the Ala-rich region, we believe that the Ala-rich region of hornet silk predominantly forms a coiled coil with an alpha-helix conformation.     

Molecular characterization and evolutionary study of spider tubuliform (eggcase) silk protein

As a result of hundreds of millions of years of evolution, orb-web-weaving spiders have developed the use of seven different silks produced by different abdominal glands for various functions. Tubuliform silk (eggcase silk) is unique among these spider silks due to its high serine and very low glycine content. In addition, tubuliform silk is the only silk produced just during a short period of time, the reproductive season, in the spider's life. To understand the molecular characteristics of the proteins composing this silk, we constructed tubuliform-gland-specific cDNA libraries from three different spider families, Nephila clavipes, Argiope aurantia, and Araneus gemmoides. Sequencing of tubuliform silk cDNAs reveals the repetitive architecture of its coding sequence and novel amino acid motifs. The inferred protein, tubuliform spidroin 1 (TuSp1), contains highly homogenized repeats in all three spiders. Amino acid composition comparison of the predicted tubuliform silk protein sequence to tubuliform silk indicates that TuSp1 is the major component of tubuliform silk. Repeat unit alignment of TuSp1 among three spider species shows high sequence conservation among tubuliform silk protein orthologue groups. Sequence comparison among TuSp1 repetitive units within species suggests intragenic concerted evolution, presumably through gene conversion and unequal crossover events. Comparative analysis demonstrates that TuSp1 represents a new orthologue in the spider silk gene family.     

Web building and silk properties functionally covary among species of wolf spider

Although phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally covary or just vary across environments that the spiders occupy. As MaSp2‐like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non‐web building, but a select few species build webs. We accordingly collected MA silk from two web‐building and six non‐web‐building species found in semirural ecosystems in Uruguay to test whether the presence of MaSp2‐like proteins (indicated by amino acid composition, silk mechanical properties and silk nanostructures) was associated with web building across the group. The web‐building and non‐web‐building species were from disparate subfamilies so we estimated a genetic phylogeny to perform appropriate comparisons. For all of the properties measured, we found differences between web‐building and non‐web‐building species. A phylogenetic regression model confirmed that web building and not phylogenetic inertia influences silk properties. Our study definitively showed an ecological influence over spider silk properties. We expect that the presence of the MaSp2‐like proteins and the subsequent nanostructures improves the mechanical performance of silks within the webs. Our study furthers our understanding of spider web and silk co‐evolution and the ecological implications of spider silk properties.     

Variation in protein intake induces variation in spider silk expression

Background

It is energetically expensive to synthesize certain amino acids. The proteins (spidroins) of spider major ampullate (MA) silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved.

Methodology/Principal Findings

We fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species'' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake.

Conclusions

Our results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact mechanics.