Difference of inducible antibacterial activity in hemolymph among the silkworm, Bombyx mori, races

Abstract

To elucidate the relationship between the interracial variation in antibacterial resistance of silkworm and its defense mechanisms, the susceptibility of 10 silkworm races was tested against the insect pathogenic bacteria, Pseudomonas aeruginosa. The difference in susceptibility was from 40 to 180 fold among the silkworm races. Furthermore, the inducible antibacterial activity of hemolymph was tested by the diffusion method against 2 insect pathogenic bacteria, P. aeruginosa and Serratia marcescens, and 2 enterobacteria, Escherichia coli and Enterobacter cloacae. In this assay, all races showed some antibacterial reaction to the enterobacteria and the activities differed among races. The race “Daizo” especially showed the highest activities in all test. However, these results of the activity tests did not always correspond with those of the susceptibility tests. The hemolymph induced antibacterial activity was examined by the method of polyacrylamide gel electrophoresis (Native-PAGE). As an antibacterial band in the gel was detected at the same mobility in all races, these differnces of the activity are likely to be caused by the quantity of antibacterial substances.