Monoclonal antibodies against brain neurosecretory a cells of Panstrongylus megistus inhibit moulting and EGG production in triatomines

Furtado, André Freire; Regis, Lêda; Falcao, Pedroi Henrique de B; Sewell, H. F.; Garcia, Elói S.

doi:10.1590/s0074-02761990000100019

“…These differences in midgut permeability and/or digestive processing of dietary proteins as a function of the insect's life stage might explain the lack of effects of canatoxin in adult R. prolixus. Regarding this point, Furtado et al (1990) have previously shown that molting of R. prolixus nymphs was affected by oral administration of monoclonal antibodies against brain neurosecretory A cells, suggesting that in- The partial sequence of the major 10,000 kD peptide present in Pool C is already known (Carlini et al, Instituto Nacional de Propriedade Industrial, Brazil, patent pending). Additional studies are under way in our laboratory to characterize the other canatoxin-derived entomotoxic peptides and to study their mode of action in order to establish their biotechnological potential against phytophagous insects.…”

Section: Discussionmentioning

confidence: 99%

Proteolytic activation of canatoxin, a plant toxic protein, by insect cathepsin‐like enzymes

Ferreira-da-Silva

¹

,

Gombarovits

²

,

Masuda

³

et al. 2000

Arch. Insect Biochem. Physiol.

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Canatoxin is a protein isolated from jackbean (Canavalia ensiformis), seeds. Injected intraperitoneally, the toxin is lethal to mice but it is inactive if given orally. Canatoxin is also lethal when fed to insects with cathepsin-based digestion while insects with trypsin-based digestion are not affected. The hypothesis that canatoxin is proteolytically activated by cathepsins was investigated. Experiments were performed with 4(th) instar and adult Rhodnius prolixus fed meals containing canatoxin (2.5 microg/mg weight body). While 100% of nymphs died, no effect was observed in adults. Hemolymph taken from nymphs and adults showed the presence of canatoxin's proteolytic fragments. Reduced lethality was seen in R. prolixus 4(th) instars fed meals containing canatoxin and inhibitors of cathepsin enzymes, E-64 (2.0 microM) or Pepstatin-A (2. 0 microM). In another approach, canatoxin was digested in vitro with enzymes from the bruchid, Callosobruchus maculatus, and the resulting peptides were tested in R. prolixus. Three groups of toxic peptides (8,000-12,000 kD range) were separated by gel-filtration. When these peptides were fed to the insects simultaneously with the cathepsin inhibitors, no protective effect was seen. These results confirm the proteolytic activation of canatoxin by insect cathepsin-like enzymes to produce entomotoxic peptide(s). Furthermore, our data point towards overlooked differences in the digestive physiology of distinct life stages of R. prolixus. Arch.

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“…These differences in midgut permeability and/or digestive processing of dietary proteins as a function of the insect's life stage might explain the lack of effects of canatoxin in adult R. prolixus. Regarding this point, Furtado et al (1990) have previously shown that molting of R. prolixus nymphs was affected by oral administration of monoclonal antibodies against brain neurosecretory A cells, suggesting that in- Figure 5. Lethal effect of canatoxin-derived peptides in R. prolixus.…”

Section: Discussionmentioning

confidence: 98%

Proteolytic activation of canatoxin, a plant toxic protein, by insect cathepsin‐like enzymes

Ferreira-da-Silva

¹

,

Gombarovits

²

,

Masuda

³

et al. 2000

Arch Insect Biochem Physiol

View full text Add to dashboard Cite

Canatoxin is a protein isolated from jackbean (Canavalia ensiformis), seeds. Injected intraperitoneally, the toxin is lethal to mice but it is inactive if given orally. Canatoxin is also lethal when fed to insects with cathepsin-based digestion while insects with trypsin-based digestion are not affected. The hypothesis that canatoxin is proteolytically activated by cathepsins was investigated. Experiments were performed with 4(th) instar and adult Rhodnius prolixus fed meals containing canatoxin (2.5 microg/mg weight body). While 100% of nymphs died, no effect was observed in adults. Hemolymph taken from nymphs and adults showed the presence of canatoxin's proteolytic fragments. Reduced lethality was seen in R. prolixus 4(th) instars fed meals containing canatoxin and inhibitors of cathepsin enzymes, E-64 (2.0 microM) or Pepstatin-A (2. 0 microM). In another approach, canatoxin was digested in vitro with enzymes from the bruchid, Callosobruchus maculatus, and the resulting peptides were tested in R. prolixus. Three groups of toxic peptides (8,000-12,000 kD range) were separated by gel-filtration. When these peptides were fed to the insects simultaneously with the cathepsin inhibitors, no protective effect was seen. These results confirm the proteolytic activation of canatoxin by insect cathepsin-like enzymes to produce entomotoxic peptide(s). Furthermore, our data point towards overlooked differences in the digestive physiology of distinct life stages of R. prolixus. Arch.

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Ecdysone modulates both ultrastructural arrangement of hindgut and attachment of Trypanosoma cruzi DM 28c to the rectum cuticle of Rhodnius prolixus fifth-instar nymph.

Lopes

¹

,

Provençano

²

,

Mello

³

et al. 2022

Experimental Parasitology

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Monoclonal antibodies against brain neurosecretory a cells of Panstrongylus megistus inhibit moulting and EGG production in triatomines

Cited by 4 publications

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Proteolytic activation of canatoxin, a plant toxic protein, by insect cathepsin‐like enzymes

Proteolytic activation of canatoxin, a plant toxic protein, by insect cathepsin‐like enzymes

Proteolytic activation of canatoxin, a plant toxic protein, by insect cathepsin‐like enzymes

Ecdysone modulates both ultrastructural arrangement of hindgut and attachment of Trypanosoma cruzi DM 28c to the rectum cuticle of Rhodnius prolixus fifth-instar nymph.

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