The expression and regulation on antimicrobial peptide genes in insects: studies in the tobacco hornworm manduca sexta
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Insects have evolved an efficient innate immune system to combat microbes. Most of our knowledge of insect immunity comes from studies with dipteran and lepidopteran insects, such as the fruit fly Drosophila melanogaster, the tobacco hornworm Manduca sexta and the silkworm Bombyx mori. One of the insect humoral responses is the induced production of antimicrobial peptides (AMPs). In D. melanogaster, bacterial peptidoglycan (PG) and fungal beta-1,3-glucan can induce AMP production by activating the Toll and the IMD (immune deficiency) pathway. Chapter 1 reviews the key features of insect innate immunity. Chapter 2 studies transcriptional upregulation of AMPs in M. sexta triggered by ultrapure LPS, LTA and PG. Chapter 3 describes species-related activities of AMP gene promoters. We determined that κB and GATA factors function in different insect species and unknown coregulators are responsible for the species-related activities. In chapter 4 the Manduca lysozyme protein was purified was purified and shown to prevent melanization by inhibiting the conversion of proPO to PO.
Table of Contents
General introduction of insect innate immunity -- Lipoteichoic acid and lipopolysaccharide can activate antimicrobial paptide expression in the tabacco hornworm manduca sexta -- Manduca sexta moricin promoter elements can differently increase promoter activities of drosophila melanogaster antimicrobial peptide genes -- The role of lysozyme in the prophenoloxidase activatio system of manduca sexta: an in vitro approach