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Transcriptional regulation of Culex pipiens mosquitoes by Wolbachia influences cytoplasmic incompatibility.

Pinto SB, Stainton K, Harris S, Kambris Z, Sutton ER, Bonsall MB, Parkhill J, Sinkins SP - PLoS Pathog. (2013)

Bottom Line: Knockdown analysis of this gene using RNAi showed an effect on hatch rates in a Wolbachia infected Culex molestus line.Furthermore, in later stages of development an effect on developmental progression in CI embryos occurs in bidirectionally incompatible crosses.The genome of a wPip Wolbachia strain variant from Culex molestus was sequenced and compared with the genome of a wPip variant with which it was incompatible.

View Article: PubMed Central - PubMed

Affiliation: Peter Medawar Building for Pathogen Research and Nuffield Department of Medicine (NDM), University of Oxford, Oxford, United Kingdom ; Department of Zoology, University of Oxford, Oxford, United Kingdom.

ABSTRACT
Cytoplasmic incompatibility (CI) induced by the endosymbiont Wolbachia pipientis causes complex patterns of crossing sterility between populations of the Culex pipiens group of mosquitoes. The molecular basis of the phenotype is yet to be defined. In order to investigate what host changes may underlie CI at the molecular level, we examined the transcription of a homolog of the Drosophila melanogaster gene grauzone that encodes a zinc finger protein and acts as a regulator of female meiosis, in which mutations can cause sterility. Upregulation was observed in Wolbachia-infected C. pipiens group individuals relative to Wolbachia-cured lines and the level of upregulation differed between lines that were reproductively incompatible. Knockdown analysis of this gene using RNAi showed an effect on hatch rates in a Wolbachia infected Culex molestus line. Furthermore, in later stages of development an effect on developmental progression in CI embryos occurs in bidirectionally incompatible crosses. The genome of a wPip Wolbachia strain variant from Culex molestus was sequenced and compared with the genome of a wPip variant with which it was incompatible. Three genes in inserted or deleted regions were newly identified in the C. molestus wPip genome, one of which is a transcriptional regulator labelled wtrM. When this gene was transfected into adult Culex mosquitoes, upregulation of the grauzone homolog was observed. These data suggest that Wolbachia-mediated regulation of host gene expression is a component of the mechanism of cytoplasmic incompatibility.

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Related in: MedlinePlus

Knockdown analysis of CPIJ005623 in C. quinquefasciatus Pel females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, BF-Blood feed, T-time point. B. KD assessment of iCPIJ005623 in Pel ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Pel male cross.
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ppat-1003647-g003: Knockdown analysis of CPIJ005623 in C. quinquefasciatus Pel females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, BF-Blood feed, T-time point. B. KD assessment of iCPIJ005623 in Pel ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Pel male cross.

Mentions: A lower level of upregulation was observed for CPIJ005623 in Pel Wolbachia-infected versus uninfected females (Figure 1B). To understand if grau upregulation is part of a generalized Culex pipiens group rescue response, we performed KD analysis followed by a compatible cross in C. quinquefasciantus Pel females (Figure 3A). Knockdown levels were assessed in dissected ovaries and a reduction of up to 40%, similar to uninfected levels was detected in the transcription of CPIJ005623 compared to control-KDs at 4 days post injection (dpi) (Figure 3B). A higher proportion of embryos arresting at stage I for iCPIJ005623 females was detected than for control-KD females (Figure 3C, Table 1) (GLM: χ2 = 23.841, Df = 1, p<0.0001). Although in Pel females unhatched rates were not affected after grau homolog KD, the shift from late to early embryo mortality is conserved in the two Culex lines.


Transcriptional regulation of Culex pipiens mosquitoes by Wolbachia influences cytoplasmic incompatibility.

Pinto SB, Stainton K, Harris S, Kambris Z, Sutton ER, Bonsall MB, Parkhill J, Sinkins SP - PLoS Pathog. (2013)

Knockdown analysis of CPIJ005623 in C. quinquefasciatus Pel females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, BF-Blood feed, T-time point. B. KD assessment of iCPIJ005623 in Pel ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Pel male cross.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814344&req=5

ppat-1003647-g003: Knockdown analysis of CPIJ005623 in C. quinquefasciatus Pel females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, BF-Blood feed, T-time point. B. KD assessment of iCPIJ005623 in Pel ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Pel male cross.
Mentions: A lower level of upregulation was observed for CPIJ005623 in Pel Wolbachia-infected versus uninfected females (Figure 1B). To understand if grau upregulation is part of a generalized Culex pipiens group rescue response, we performed KD analysis followed by a compatible cross in C. quinquefasciantus Pel females (Figure 3A). Knockdown levels were assessed in dissected ovaries and a reduction of up to 40%, similar to uninfected levels was detected in the transcription of CPIJ005623 compared to control-KDs at 4 days post injection (dpi) (Figure 3B). A higher proportion of embryos arresting at stage I for iCPIJ005623 females was detected than for control-KD females (Figure 3C, Table 1) (GLM: χ2 = 23.841, Df = 1, p<0.0001). Although in Pel females unhatched rates were not affected after grau homolog KD, the shift from late to early embryo mortality is conserved in the two Culex lines.

Bottom Line: Knockdown analysis of this gene using RNAi showed an effect on hatch rates in a Wolbachia infected Culex molestus line.Furthermore, in later stages of development an effect on developmental progression in CI embryos occurs in bidirectionally incompatible crosses.The genome of a wPip Wolbachia strain variant from Culex molestus was sequenced and compared with the genome of a wPip variant with which it was incompatible.

View Article: PubMed Central - PubMed

Affiliation: Peter Medawar Building for Pathogen Research and Nuffield Department of Medicine (NDM), University of Oxford, Oxford, United Kingdom ; Department of Zoology, University of Oxford, Oxford, United Kingdom.

ABSTRACT
Cytoplasmic incompatibility (CI) induced by the endosymbiont Wolbachia pipientis causes complex patterns of crossing sterility between populations of the Culex pipiens group of mosquitoes. The molecular basis of the phenotype is yet to be defined. In order to investigate what host changes may underlie CI at the molecular level, we examined the transcription of a homolog of the Drosophila melanogaster gene grauzone that encodes a zinc finger protein and acts as a regulator of female meiosis, in which mutations can cause sterility. Upregulation was observed in Wolbachia-infected C. pipiens group individuals relative to Wolbachia-cured lines and the level of upregulation differed between lines that were reproductively incompatible. Knockdown analysis of this gene using RNAi showed an effect on hatch rates in a Wolbachia infected Culex molestus line. Furthermore, in later stages of development an effect on developmental progression in CI embryos occurs in bidirectionally incompatible crosses. The genome of a wPip Wolbachia strain variant from Culex molestus was sequenced and compared with the genome of a wPip variant with which it was incompatible. Three genes in inserted or deleted regions were newly identified in the C. molestus wPip genome, one of which is a transcriptional regulator labelled wtrM. When this gene was transfected into adult Culex mosquitoes, upregulation of the grauzone homolog was observed. These data suggest that Wolbachia-mediated regulation of host gene expression is a component of the mechanism of cytoplasmic incompatibility.

Show MeSH
Related in: MedlinePlus