Encapsulation is the immune response in which insect hemocytes attach to a large metazoan parasite, thus forming a cellular capsule around the foreign invader and rendering it inactive. In the moth Manduca sexta (Sphingidae: Lepidoptera), the two hemocyte types involved in encapsulation are plasmatocytes and granulocytes. In a previous study, the monoclonal antibody MS34, which is specific to M. sexta plasmatocytes, was found to inhibit encapsulation. MS34 was then used to purify a protein approximately 90 kDa in size. Edman degradation of trypsin fragments of this protein revealed short peptide sequences which were used to design degenerate primers. 5¢ and 3¢ RACE using hemocyte total RNA resulted in a DNA sequence with an open reading frame of 2301 bp and a deduced amino acid sequence of 767 residues. The deduced amino acid sequence is highly similar to b-integrins which are transmembrane proteins mediating cell adhesion. In this study, in situ hybridization of M. sexta hemocytes and hematopoietic organs, and Northern blot analysis of hemocyte RNA from naive and bacteria challenged moths were performed to determine the prevalence of this protein in the tobacco hornworm.
Species 1: Lepidoptera Sphingidae Manduca sexta (tobacco hornworm)
Keywords: hemocytes, cell adhesion
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