FLAGELLIFORM OR CORONATA GLANDS OF NEPHILA-CLAVIPES

The flagelliform or coronata glands of the orb-web spider, Nephila cla vipes, have been studied and compared to other silk-producing glands f rom the organism. The glands, which produce silk for the double filame nt of the core thread in the sticky spiral, exhibit three distinct mor phological areas: tail, sac, and duct. Electrophoretic separation of t he solubilized contents of the glands yields an uppermost diffuse band of high molecular size, preceded by a stepladder of well-defined pept ides, which have been shown to be products of discontinuous translatio n in three other sets of glands. The luminal contents do not migrate a s a discrete and well-defined band as those of the other glands, but r ather as a diffuse area, typical of glycosylated proteins. Fibroin syn thesis is stimulated by the mechanical depletion of the organism's sto red silks, as in other Nephila glands, judged by the increased intensi ty of the bands and also by the structural alterations seen in cross s ections of the glands' tails. (C) 1995 Wiley-Liss, Inc.