The secretion proteins in Chironomus tentans salivary glands: Electrophoretic characterization and molecular weight estimation

Abstract

A new method for isolating the secretion products fromChironomus tentans salivary glands is described. This method has the advantage of allowing the isolation of soluble and undegraded secretion proteins. These proteins have been characterized on SDS-acrylamide gels. Three main proteins (SPI, SPII, and SPIII), with molecular weights of about 1.4, 1.0 and 0.16×10 D were detected. The number of major bands is that expected if, as has been suggested, the three Balbiani rings on the fourth chromosome contain the genes for the secretion proteins. Moreover, the molecular weights of SPI and SPII are in the range expected from the size of Balbiani ring transcripts. In addition we present evidence for a protease which is isolated with the secretion proteins and is fully active only in the presence of reducing agents. This result suggests that a secondary structure, maintained by disulfide bonds, is necessary to prevent proteolytic cleavage of secretion proteins.

Developmental changes in the responsiveness to ecdysterone of chromosome region I-18C of Chironomus tentans

“…Salivary glands were rinsed and incubated in NKE (100 mM NaC1, 5 mM KC1, 0.5 mM EDTA, 10 mM Tris-maleate, pH 6.3) in order to sotubilize the secretion from the opened lumen (Hertner et al 1980). They were then incubated for 1 rain in ice-cold Glancy medium containing 0.1% Triton X-100, transferred into 50% acetic acid, and squashed.…”

Possible correlations of polypeptides and Balbiani rings in the salivary glands of Drosophila auraria Peng.

“…Balbiani rings have been studied intensively in several species of Chironomidae and these studies have resulted both to an understanding of their molecular structure and to the identification of two huge polypeptides which comprise the main secretory products of the salivary glands of the species studied (Hardy & Pelling, 1980;Hertner et al, 1980;Rydlander & Edstr6m, 1980;B~umlein et al, 1982a, b;J~ckle et al, 1982;Siimegi et al, 1982;Wieslander et al, 1982).…”

Aquatic silk proteins in Chironomus: A review

“…4). SpIs are the large size class, with an estimated molecular mass of 1000 kDa which include spIa, spIb, spIc and spId (Rydlander et al, 1980b;Hertner et al, 1980;Hardy and Pelling, 1980). The intermediate size class contains secretory proteins from about 100 to 200 kDa and include sps195, 185, 140 and 115.…”

“…As highlighted by Case and Wieslander (1992) in the 1980s five laboratories in the world concurrently used gDNA and cDNA cloning to study the spI genes in C. tentans, C. pallidivittatus and C. riparius, which revealed that the primary structure of spIs as characteristic of fibrous proteins. They contain tandem copies of distinctive core repeats which are dominated by hydrophilic amino acids and conserved Cysteine (Cys) residues in most cases (Rydlander et al, 1980;Hertner et al, 1980Hertner et al, , 1983Rydlander, 1984;Hamodrakas and Kafatos, 1984;Kao and Case, 1985). Each core repeat contains 60-90 amino acids and possesses two domains: a constant (C) region and a subrepeat (SR) region.…”

“…honeybees, crickets, ants, hornets, lacewings, silverfish, caddis flies and chironomid midges (Weisman et al, 2008;Sehnal and Sutherland, 2008;Sutherland et al 2010;Walker et al, 2012;Sutherland et al, 2011). In the purview of aquatic silks spun underwater, the retreat maker caddisworms (Stewart and Wang 2010;Tsukada et al, 2010;Ohkawa et al, 2014;Ashton et al, 2016) and larval chironomid midges (Grossbach, 1977;Hertner et al, 1980;Wellman and Case, 1989;Case et al, 1994) have exhibited how habitats influence the nature, composition and properties of silk. This review focusses on the underexplored silk-spinning expertise and the little known physiological biochemistry of silk protein produced by Chironomus larvae.…”