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Anopheles gambiae cadherin AgCad1 binds the Cry4Ba toxin of Bacillus thuringiensis israelensis and a fragment of AgCad1 synergizes toxicity.

ABSTRACT: A midgut cadherin AgCad1 cDNA was cloned from Anopheles gambiae larvae and analyzed for its possible role as a receptor for the Cry4Ba toxin of Bacillus thuringiensis strain israelensis. The AgCad1 cadherin encodes a putative 1735-residue protein organized into an extracellular region of 11 cadherin repeats (CR) and a membrane-proximal extracellular domain (MPED). AgCad1 mRNA was detected in midgut of larvae by polymerase chain reaction (PCR). The AgCad1 protein was localized, by immunochemistry of sectioned larvae, predominately to the microvilli in posterior midgut. The localization of Cry4Ba binding was determined by the same technique, and toxin bound microvilli in posterior midgut. The AgCad1 protein was present in brush border membrane fractions prepared from larvae, and Cry4Ba toxin bound the same-sized protein on blots of those fractions. The AgCad1 protein was expressed transiently in Drosophila melanogaster Schneider 2 (S2) cells. 125I-Cry4Ba toxin bound AgCad1 from S2 cells in a competitive manner. Cry4Ba bound to beads extracted 200 kDa AgCad1 and a 29 kDa fragment of AgCad1 from S2 cells. A peptide containing the AgCad1 region proximal to the cell (CR11-MPED) was expressed in Escherichia coli. Although Cry4Ba showed limited binding to CR11-MPED, the peptide synergized the toxicity of Cry4Ba to larvae. AgCad1 in the larval brush border is a binding protein for Cry4Ba toxin. On the basis of binding results and CR11-MPED synergism of Cry4Ba toxicity, AgCad1 is probably a Cry4Ba receptor.

SUBMITTER: Hua G

PROVIDER: S-EPMC2662694 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Anopheles gambiae cadherin AgCad1 binds the Cry4Ba toxin of Bacillus thuringiensis israelensis and a fragment of AgCad1 synergizes toxicity.

Hua Gang G Zhang Rui R Abdullah Mohd Amir F MA Adang Michael J MJ

Biochemistry 20080412 18

A midgut cadherin AgCad1 cDNA was cloned from Anopheles gambiae larvae and analyzed for its possible role as a receptor for the Cry4Ba toxin of Bacillus thuringiensis strain israelensis. The AgCad1 cadherin encodes a putative 1735-residue protein organized into an extracellular region of 11 cadherin repeats (CR) and a membrane-proximal extracellular domain (MPED). AgCad1 mRNA was detected in midgut of larvae by polymerase chain reaction (PCR). The AgCad1 protein was localized, by immunochemistry ...[more]

PMID: 18407662

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Project description:BACKGROUND:Biotic and abiotic factors have been reported to affect the larvicidal efficacy of Bacillus thuringiensis israelensis (Bti) and Bacillus sphaericus (Bs), although the extent to which they are affected has been poorly documented. This paper studies the effect of sunlight exposure on the efficacy of a new larvicide formulation based on both Bti and Bs, herein after referred to as BTBSWAX, applied against two different larval stages. METHODS:The emergence of inhibition exhibited by BTBSWAX at three different dosages (1 g/m2, 1.5 g/m2, and 2 g/m2) was monitored under semi-field conditions using a total of 32 containers comprising 16 that were covered and 16 that were uncovered. Two experiments were conducted using first- and second-instar larvae of Anopheles gambiae, respectively. RESULTS:BTBSWAX at 2 g/m2 in covered containers exhibited high emergence inhibition (>?80%) when larvae were exposed from 1st instar on day-6 post-treatment, whereas the emergence inhibition was only 28% in uncovered containers. For larvae exposed from 1st instar on day-12 post-treatment, the emergence inhibition was moderate (70%) in covered containers but was low (<?20%) in uncovered containers. For larvae exposed from 2nd instar on day-10 post-treatment, the emergence inhibition was moderate (31%) in covered containers but was very low (<?10%) in uncovered containers. Moreover, the residual efficacy of BTBSWAX was markedly affected by environmental stresses, including sunlight exposure (Hazard ratio (HR)?=?0.12, p?<?0.001 and HR?=?0.63, p?=?0.033 for BTBSWAX at 2 g/m2 against 1st and 2nd instar larvae, respectively). CONCLUSION:These findings emphasize the impact of environmental variables (e.g., sunlight exposure) on the residual efficacy of Bti and Bs biolarvicides in the field. They hence highlight the need to take these factors into account for larvicide formulation development processes. Moreover, studies of the ecology of Anopheles larvae in targeted areas are also crucial for the integration of larval control strategies into malaria transmission plans devised by national malaria control programmes of endemic countries.

Dataset Information

Anopheles gambiae cadherin AgCad1 binds the Cry4Ba toxin of Bacillus thuringiensis israelensis and a fragment of AgCad1 synergizes toxicity.

Publications

Anopheles gambiae cadherin AgCad1 binds the Cry4Ba toxin of Bacillus thuringiensis israelensis and a fragment of AgCad1 synergizes toxicity.

Similar Datasets

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