Silkworm functionalization

FIGURE 24.4 Silkworm genetic loci responsible for carotenoid transport, (a) List of the genetic loci. + indicates a recessive allele of I. (b) Schematic illustration of the function of the F, I, and C genes. Only larvae with the genotype Y + C] transport carotenoids into the silk gland and create yellow cocoons. 

Nakajima, M. 1963. Physiological studies on the function of genes concerning carotenoid permeability in the silkworm. Bull. Fac. Agric. Tokyo Univ. Agric. Technol., 8 1-80. 

The biological activity of the silkworm moth sex attractant, a pheromone, is a very sensitive function of the geometry around its two double bonds. 

As a functional analysis of animal development, an accurate fate map was carried out using the silkworm, Bombyx mod [128]. Among the beam sizes tested (60- to 250-pm c[)), 250-pm c[) was adopted for the fate mapping of egg at the cellular blastderm stage. When eggs were irradiated near the anterior, posterior, or dorsal periphery, no defective larvae were observed. A close correlation was observed between the site of irradiation and the site of the defect induced. Head defects were induced only by irradiation at the anterior half of the egg, whereas defects in thoracic and abdominal segments were induced by irradiation at the middle and the posterior part of the egg, respectively. Based on the correlations, a fate map of the B. mod egg was established [128]. 

Not all of the fibroin protein is in / -sheets. As the amino acid composition in Figure 6.12 shows, fibroin contains small amounts of other, bulky amino acids like valine and tyrosine, which would not fit into the structure shown. These are carried in compact folded regions that periodically interrupt the sheet segments, and they probably account for the amount of stretchiness that silk fibers have. In fact, different species of silkworms produce fibroins with different extents of such non - / -sheet structure and corresponding differences in elasticity. The overall fibroin structure is a beautiful example of a protein molecule that has evolved to perform a particular function — to provide a tough, yet flexible fiber for the silkworm s cocoon or the spider s web. 

Most ligands bound by PBPs and OBPs contain long, aliphatic hydrocarbon chains. Some have a polar functionality at one end of the chain such as (6E, 1IZ) hexadeca-6,11-dienyl-l-acetate and the corresponding aldehyde which comprise the pheromonal blend of A. polyphemus, or (10 , 12Z) hexadec-10,12-dien-l-ol (bombykol), the first chemically characterized pheromone, from the silkworm moth... 

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