Release of Mediator Enzyme β-Hexosaminidase and Modulated Gene Expression Accompany Hemocyte Degranulation in Response to Parasitism in the Silkworm Bombyx mori
In insects infections trigger hemocyte-mediated immune reactions including degranulation by exocytosis; however, involvement of mediator enzymes in degranulation process is unknown in insects. We report here that in silkworm Bombyx mori , infection by endoparasitoid Exorista bombycis and microsporid...
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Published in: | Biochemical genetics 2021-08, Vol.59 (4), p.997-1017 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | In insects infections trigger hemocyte-mediated immune reactions including degranulation by exocytosis; however, involvement of mediator enzymes in degranulation process is unknown in insects. We report here that in silkworm
Bombyx mori
, infection by endoparasitoid
Exorista bombycis
and microsporidian
Nosema bombycis
activated granulation in granulocytes and promoted degranulation of accumulated structured granules. During degranulation the mediator lysosomal enzyme β-hexosaminidase showed increased activity and expression of
β-hexosaminidase
gene was enhanced. The events were confirmed in vitro after incubation of uninfected hemocytes with
E. bombycis
larval tissue protein. On infection, cytotoxicity marker enzyme lactate dehydrogenase (LDH) was released from the hemocytes illustrating cell toxicity. Strong positive correlation (
R
2
= 0.71) between LDH activity and β-hexosaminidase released after the infection showed parasitic–protein-induced hemocyte damage and accompanied release of the enzymes. Expression of
β-hexosaminidase
gene was enhanced in early stages after infection followed by down regulation. The expression showed positive correlation (
R
2
= 0.705) with hexosaminidase activity pattern.
B. mori
hexosaminidase showed 98% amino acid similarity with that of
B. mandarina
showing origin from same ancestral gene; however, 45–60% varied from other lepidopterans showing diversity. The observation signifies the less known association of hexosaminidase in degranulation of hemocytes induced by parasitic infection in
B. mori
and its divergence in different species. |
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ISSN: | 0006-2928 1573-4927 |
DOI: | 10.1007/s10528-021-10046-x |