pH and water regulation in the silk gland of Bombyx mori in relation to gel-sol transition of the liquid silk in the glandular lumen

家蚕丝腺中 pH 值和水分调节与腺腔内液体丝凝胶-溶胶转变的关系

基本信息

批准号：
12660054
负责人：
AZUMA Masaaki
金额：
$ 2.37万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12660054/
关键词：
V-ATPase water channel silk gland liquid silk active transport silkworm, Bombyx mori 水チャンネル

项目摘要

The silk gland is a unique and indispensable tissue to produce the silk proteins (fibroin and sericin), making a cocoon. The gland secretes and temporarily stores the silk proteins within the glandular lumen without any denaturation of proteins till the larva starts to spin. The concentrations in the secreted protein reach up to 20-30 % levels. Such a high concentration of the protein solution has to be regulated under a certain pH ranges and a fixed water content. We have investigated such a mechanism to understand the ionic homeostasis and osmoregulation in the gland. Results are as follows :(1) Immunocytochemical studies were done with the specific anitibody against V-ATPase. The V-ATPase can be detected in the middle silk gland cell(MSG) as well as in the anterior silk gland (ASG) cell. V-ATPase was located at the cell surface, suggesting that this V-ATPase is a plasma membrane-type not an endomembrane-type such as the V-ATPase in lysosomes and secretory vesicles.(2) The similar plasma membrane V-ATPase detected in another cocoon-producing lepidopteran insect, Eri-silkworm (Samia cynthia ricini), but not in the labial gland from the sweet potato hornworm, Agrius convolvuli, where we have detected the endomembrane V-ATPase in the cytoplasm. Thus, the presence of plasma membrane V-ATPase is a unique feature in the silk gland of lepidoptera.(3) By the homology cloning strategy, we have patially cloned the putative water channel (aquaporin, AQP) in the silk gland of Bombyx mori. This putative AQP is highly expressed in the ASG at the feeding stage of the 5th instar. The expression of the putative AQP seems to be stopped at the onset of spinning. Thus, it is suggested that the AQP as well as V-ATPase is closely related to the silk gland development and the cocoon production during larval-pupal metamorphosis.

丝绸腺是一种独特且必不可少的组织，可产生丝绸蛋白（纤维蛋白和塞他蛋白），形成茧。腺体分泌，并暂时将丝蛋白储存在腺腔内，而无需蛋白质变性，直到幼虫开始旋转。分泌蛋白的浓度高达20-30％。这种高浓度的蛋白质溶液必须在一定的pH范围和固定的水含量下进行调节。我们已经调查了一种理解腺体离子稳态和渗透调节的机制。结果如下：（1）使用针对V-ATPase的特异性抗体进行免疫细胞化学研究。可以在中间丝绸细胞（MSG）以及前丝腺（ASG）细胞中检测到V-ATPase。 V-ATPase位于细胞表面，表明该V-ATPase是一种质膜类型，而不是溶酶体和分泌囊泡中的V-ATPase，而不是质膜类型的。 ricini），但不在红薯中虫（Agrius ogrius vercolvuli）的唇腺中，在那里我们检测到了细胞质中的内膜V-ATPase。因此，质膜V-ATPase的存在是鳞翅目丝腺中的独特特征。（3）通过同源性克隆策略，我们在Bombyx Mori的丝绸粘膜中专门克隆了假定的水通道（Aquaporin，aqp，AQP）。该推定的AQP在第5龄龄阶段的ASG中高度表达。推定的AQP的表达似乎在旋转开始时停止了。因此，建议AQP和V-ATPase与幼虫型变形期间的丝腺发育和茧产生密切相关。