Date of Award
1989
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
The crystalline cone of beetles and moths is a transparent, solid structure consisting of a small number of concentrated, hydrophobic proteins. Among these polypeptides is a 67kD protein family which are found in the cones of all 9 species examined. In addition, beetle lenses contain a 125kD polypeptide that is immunologically related to a moth 100kD lens polypeptide. The high molecular weight polypeptides may also be related to the 67kD family because (i) antibodies raised against the beetle 67kD polypeptide cross-react with the moth 67kD and 100kD polypeptides, and with the beetle 125kD polypeptide, (ii) enzyme digests of 67kD and 100kD moth polypeptides yield a number of products of identical mass, and (iii) the purified 67 and 100kD polypeptides dissociate into subunits of similar molecular weight.;The profiles of crystalline cone proteins in lepidopterans and beetles may result from the cone being formed differently. In Calpodes, the proteins are synthesized and deposited in a coordinate manner in the pupa; the cone is nearly complete at adult emergence. In Onitis, the proteins are synthesized and deposited in a temporal manner; the cone is only 70% complete at adult emergence. In both species, the crystalline cone grows by deposition of granules of proteins onto a specialized region of cone cell surface (the plasma membrane template). Subsequent growth in Calpodes involves the appearance of a sponge-like scaffold which becomes packed with protein. In Onitis, newly synthesized protein fuses uniformly around the cone axis, giving rise to cross-sectional profiles which are at first starlike, then square, and finally circular.;A template membrane connecting the four cone cells is the initial site for the ordered deposition of cone protein. The structure of this template defines the limits and volume of the cone. Cone proteins will not fuse with other regions of the plasma membrane, and in the template's absence form random aggregates. A template membrane fraction can be obtained from Calpodes by a two-step urea solubilization which leaves the template intact. It is associated with one 67kD isoform and with the 100kD polypeptide.
Recommended Citation
Schlamp, Cassandra Lee, "Composition, Structure And Development Of The Crystalline Cone Of The Superposition Compound Eye" (1989). Digitized Theses. 1851.
https://ir.lib.uwo.ca/digitizedtheses/1851