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Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål).
Toxicon. 2010 Jun 01; 55(6):1162-70.T

Abstract

The production of peptide toxins by entomopathogenic fungi during the infection process plays critical roles in pathogenesis. To gain insight into the mechanism of action of these mycotoxins on insect internal organs, we have evaluated the effects of destruxin A, a cyclic peptide produced by Metarhizium anispliae, on Rhodnius prolixus Malpighian tubules measuring fluid secretion rate, transepithelial electrical potential (TEP), pH and ion composition of secreted fluid, and ATP content. Destruxin A dramatically inhibited fluid secretion rate on tubules stimulated by 5-Hydroxytryptamine (5-HT) or cAMP. The calculated IC(50) for destruxin A on 5-HT-stimulated tubules was 3 x 10(-7) M. Fluid secretion rate by Malpighian tubules exposed for 20 min to 10(-6) M destruxin A recovered completely when tubules were washed with saline; however, when tubules were exposed to 5 x 10(-6) M destruxin A the fluid secretion rate only partially recovered upon wash off. The use of Ca(2+)-free saline or addition of the calcium channel blocker CoCl(2) to the bathing saline did not interfere with the effects of destruxin A, and neither did the modification of intracellular calcium by TMB-8. Measurement of TEP of tubules challenged with 5-HT after preincubation for 10 min in saline containing 10(-6) M destruxin A showed that the second and third phases of the typical triphasic response to 5-HT were disrupted. Likewise, the positive shift in TEP in response to 5-HT in chloride-free bathing saline was significantly reduced when tubules were preincubated for 10 min in 10(-6) M destruxin A. The pH of the secreted fluid, but not the Na(+) or K(+) concentration, increased significantly when 5-HT-stimulated tubules were exposed to 10(-6) M destruxin A. The ATP content was not significantly different when tubules stimulated with 5-HT were exposed to destruxin A. Taken together, these results show that destruxin A, without interfering with the intracellular ATP production, strongly inhibits fluid secretion rate by the Malpighian tubules of R. prolixus. Changes in properties of the TEP suggest that one of the target sites for this peptide toxin might be associated with inhibition of the apical V-type H(+) ATPase of tubule cells.

Authors+Show Affiliations

Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada. e.ruiz.sanchez@utoronto.caNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20060849

Citation

Ruiz-Sanchez, Esau, et al. "Effects of the Cyclopeptide Mycotoxin Destruxin a On the Malpighian Tubules of Rhodnius Prolixus (Stål)." Toxicon : Official Journal of the International Society On Toxinology, vol. 55, no. 6, 2010, pp. 1162-70.
Ruiz-Sanchez E, Orchard I, Lange AB. Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål). Toxicon. 2010;55(6):1162-70.
Ruiz-Sanchez, E., Orchard, I., & Lange, A. B. (2010). Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål). Toxicon : Official Journal of the International Society On Toxinology, 55(6), 1162-70. https://doi.org/10.1016/j.toxicon.2010.01.006
Ruiz-Sanchez E, Orchard I, Lange AB. Effects of the Cyclopeptide Mycotoxin Destruxin a On the Malpighian Tubules of Rhodnius Prolixus (Stål). Toxicon. 2010 Jun 1;55(6):1162-70. PubMed PMID: 20060849.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål). AU - Ruiz-Sanchez,Esau, AU - Orchard,Ian, AU - Lange,Angela B, Y1 - 2010/01/10/ PY - 2009/09/22/received PY - 2009/12/31/revised PY - 2010/01/05/accepted PY - 2010/1/12/entrez PY - 2010/1/12/pubmed PY - 2010/6/10/medline SP - 1162 EP - 70 JF - Toxicon : official journal of the International Society on Toxinology JO - Toxicon VL - 55 IS - 6 N2 - The production of peptide toxins by entomopathogenic fungi during the infection process plays critical roles in pathogenesis. To gain insight into the mechanism of action of these mycotoxins on insect internal organs, we have evaluated the effects of destruxin A, a cyclic peptide produced by Metarhizium anispliae, on Rhodnius prolixus Malpighian tubules measuring fluid secretion rate, transepithelial electrical potential (TEP), pH and ion composition of secreted fluid, and ATP content. Destruxin A dramatically inhibited fluid secretion rate on tubules stimulated by 5-Hydroxytryptamine (5-HT) or cAMP. The calculated IC(50) for destruxin A on 5-HT-stimulated tubules was 3 x 10(-7) M. Fluid secretion rate by Malpighian tubules exposed for 20 min to 10(-6) M destruxin A recovered completely when tubules were washed with saline; however, when tubules were exposed to 5 x 10(-6) M destruxin A the fluid secretion rate only partially recovered upon wash off. The use of Ca(2+)-free saline or addition of the calcium channel blocker CoCl(2) to the bathing saline did not interfere with the effects of destruxin A, and neither did the modification of intracellular calcium by TMB-8. Measurement of TEP of tubules challenged with 5-HT after preincubation for 10 min in saline containing 10(-6) M destruxin A showed that the second and third phases of the typical triphasic response to 5-HT were disrupted. Likewise, the positive shift in TEP in response to 5-HT in chloride-free bathing saline was significantly reduced when tubules were preincubated for 10 min in 10(-6) M destruxin A. The pH of the secreted fluid, but not the Na(+) or K(+) concentration, increased significantly when 5-HT-stimulated tubules were exposed to 10(-6) M destruxin A. The ATP content was not significantly different when tubules stimulated with 5-HT were exposed to destruxin A. Taken together, these results show that destruxin A, without interfering with the intracellular ATP production, strongly inhibits fluid secretion rate by the Malpighian tubules of R. prolixus. Changes in properties of the TEP suggest that one of the target sites for this peptide toxin might be associated with inhibition of the apical V-type H(+) ATPase of tubule cells. SN - 1879-3150 UR - https://www.unboundmedicine.com/medline/citation/20060849/Effects_of_the_cyclopeptide_mycotoxin_destruxin_A_on_the_Malpighian_tubules_of_Rhodnius_prolixus__Stål__ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0041-0101(10)00007-3 DB - PRIME DP - Unbound Medicine ER -