Vicilins (7S storage globulins) of cowpea (Vigna unguiculata) seeds bind to chitinous structures of the midgut of Callosobruchus maculatus (Coleoptera: Bruchidae) larvae
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Abstract
The presence of chitin in midgut structures of Callosobruchus maculatus
larvae was shown by chemical and immunocytochemical methods.
Detection by Western blotting of cowpea (Vigna unguiculata)
seed vicilins (7S storage proteins) bound to these structures suggested
that C. maculatus-susceptible vicilins presented less staining when
compared to C. maculatus-resistant vicilins. Storage proteins present
in the microvilli in the larval midgut of the bruchid were recognized by
immunolabeling of vicilins in the appropriate sections with immunogold
conjugates. These labeling sites coincided with the sites labeled by an
anti-chitin antibody. These results, taken together with those previously
published showing that the lower rates of hydrolysis of variant
vicilins from C. maculatus-resistant seeds by the insect s midgut
proteinases and those showing that vicilins bind to chitin matrices,
may explain the detrimental effects of variant vicilins on the development
of C. maculatus larvae