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Postdoctoral position on selfish phage genes and symbionts in Drosophila The Bordenstein Lab in the Department of Biological Sciences and the Vanderbilt Microbiome Initiative in Nashville, TN is seeking a postdoc to join a new, symbiosis project on the molecular mechanism of symbiont-induced male killing using the Wolbachia-Drosophila melanogaster model system. The project explores the function of the phage WO gene wmk that is a candidate for selectively killing males. Male killing can drive through arthropod populations worldwide and potentially be deployed as an insect control tool. Related publication: Interested in joining our team? Contact Seth Bordenstein at | with informal inquires or a single pdf containing your statement of interest, CV, and two first author publications. Experience in Drosophila is preferred.

Biological Sciences & Pathology, Microbiology, and Immunology

Despite nearly sixty years of study, the microbial genetic and mechanistic bases of how Wolbachia cause sex-specific lethality in their hosts remain largely unresolved, and the rising interest in deploying Wolbachia for human benefit necessitates an explanation of this cunning bacteria's enigmatic effects on host biology. The proposed research will advance, for the first time, a fundamental understanding of the wmk gene product and its molecular interactions. In addition, knowledge on the essential wmk regions and host target DNA/interactors will inform downstream consideration of how a male-killing toxin could be deployed in the long term to suppress or eradicate populations of arthropod pests and disease vectors. 

Aim 1. Assess potential interactions between Wmk and host fly DNA. Does Wmk act as a transcription factor to induce male killing? We will assess if Wmk binds DNA and identify which sequences are bound using ChIP-seq. We will also evaluate misregulation of the transcriptome in males expressing wmk compared to controls using RNA-seq. Finally, to functionally validate candidate host targets from the above subaims, we will identify top candidates from each individual 'omic analysis and candidates from an integrated 'omic approach. We will then use express wmk and controls in mutant Drosophila for each candidate to determine if male killing depends on the host genes.

Aim 2. Determine the mode of Wmk exit from the Wolbachia cell to reach the host. Is Wmk secreted from Wolbachia or released from the cell via phage or vesicles? To determine if Wmk can be secreted by a type IV secretion system, we will express Wmk in a previously developed, heterologous E. coli expression system with Wolbachia T4SS components to determine if it can be secreted. Wmk, a protein of prophage origin, may depend on phage or secretory vesicles to exit the bacteria in natural contexts. Therefore, we will perform viral and vesicle purifications, TEM, and PCR from fly embryos infected with Wolbachia. This will assess if natural male killers produce WO particles or vesicles that could mediate Wmk exit from the cell. 

Aim 3. Interrogate regions of wmk sequence necessary to induce male death. Which regions of Wmk are required for selective lethality of males? When must wmk be expressed to kill males? We hypothesize that the entire gene and early embryonic expression are required for wmk male killing. Wmk has two predicted helix-turn-helix DNA-binding domains connected by a linker region and flanked by N- and C-termini. To test which, if any, smaller regions of Wmk are required for Wmk function, we will create transgenic wmk fly lines with one or more domains deleted. We will then assess resulting host sex ratios. To identify the key time window(s) for lethality and putative target host processes, we will express wmk under a heat shock-inducible driver at different periods in embryonic and later development and assess resulting sex ratios.

Contact Seth Bordenstein at | with informal inquires or a single pdf containing your statement of interest, CV, and two first author publications. Experience in Drosophila is preferred.

Seth Bordenstein
2020-09-24 16:33:37

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