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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. molestus Italy females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, T-time point. B. KD assessment of iCPIJ005623 in Italy ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Picture examples of developmental progression in Culex embryos undergoing CI, Stage I: early arrest, Stage II and III: late arrest. D. Increased percentage of unhatched embryos mimic a reduced rescue function. Also increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Italy male cross.
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ppat-1003647-g002: Knockdown analysis of CPIJ005623 in C. molestus Italy females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, T-time point. B. KD assessment of iCPIJ005623 in Italy ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Picture examples of developmental progression in Culex embryos undergoing CI, Stage I: early arrest, Stage II and III: late arrest. D. Increased percentage of unhatched embryos mimic a reduced rescue function. Also increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Italy male cross.

Mentions: Given the upregulation of CPIJ005623 detected in the Italy Wolbachia-infected line compared to uninfected females, we knocked down the gene in infected females using dsRNA to investigate whether this change may be involved in the rescue function of CI. Restoring transcription to uninfected levels in these females might result in developmental arrest in embryos from crosses with Wolbachia-infected males (Figure 2A). Knockdown (KD) levels were assessed in dissected ovaries and a reduction of approximately 50% was detected in the transcription of CPIJ005623 in iCPIJ005623-injected females compared to iLacZ-injected control-KD females at 4 days post injection (dpi) which were similar to PelU ovarian expression levels (Figure 2B). An increase in the number of unhatched eggs was detected in a compatible cross of Italy males with iCPIJ005623 females (48.7%) compared to control-KDs (37.9%) (Table 1- Welch's t-test: t = 8.975, Df = 39.861, p<0.0001).


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. molestus Italy females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, T-time point. B. KD assessment of iCPIJ005623 in Italy ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Picture examples of developmental progression in Culex embryos undergoing CI, Stage I: early arrest, Stage II and III: late arrest. D. Increased percentage of unhatched embryos mimic a reduced rescue function. Also increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Italy male cross.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1003647-g002: Knockdown analysis of CPIJ005623 in C. molestus Italy females.A. Diagram representing experimental design of knockdown (KD) experiments, d-day post pupal eclosion, T-time point. B. KD assessment of iCPIJ005623 in Italy ovaries. Reduction of CPIJ005623 mRNA levels similar to uninfected ovaries was observed in infected ovaries when CI developmental progression was seen. C. Picture examples of developmental progression in Culex embryos undergoing CI, Stage I: early arrest, Stage II and III: late arrest. D. Increased percentage of unhatched embryos mimic a reduced rescue function. Also increased early embryo (stageI) developmental arrest is detected after iCPIJ005623 in compatible Italy male cross.
Mentions: Given the upregulation of CPIJ005623 detected in the Italy Wolbachia-infected line compared to uninfected females, we knocked down the gene in infected females using dsRNA to investigate whether this change may be involved in the rescue function of CI. Restoring transcription to uninfected levels in these females might result in developmental arrest in embryos from crosses with Wolbachia-infected males (Figure 2A). Knockdown (KD) levels were assessed in dissected ovaries and a reduction of approximately 50% was detected in the transcription of CPIJ005623 in iCPIJ005623-injected females compared to iLacZ-injected control-KD females at 4 days post injection (dpi) which were similar to PelU ovarian expression levels (Figure 2B). An increase in the number of unhatched eggs was detected in a compatible cross of Italy males with iCPIJ005623 females (48.7%) compared to control-KDs (37.9%) (Table 1- Welch's t-test: t = 8.975, Df = 39.861, p<0.0001).

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