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The genetics of sex determination and sexual mode switching in crustaceans


About This PhD Project

Project Description

There is great interest in understanding the mechanisms by which sex is determined in aquaculture species in order to develop more sustainable and productive breeding [1] and so enhance food security, a BBSRC priority area. In crustaceans, an important global food source, the basic understanding of the pathways underlying sexual development is limited [2, 3] and more basic research is required.
This project aims to help fill this knowledge gap using a model crustacean, Triops cancriformis, that is easy to keep in the lab and has a small genome (~125Mb). Importantly, in collaboration with others, we have shown that this species shows variable sexual mode, with both dioecious populations (separate males and females that mate with one another) and derived self-fertilising hermaphrodite populations. Furthermore, some populations have both self-fertilising hermaphrodites and males. Understanding the genetic changes underlying this switch would provide foundational information for understanding how to control sexual mode in other crustaceans.
With collaborators we have assembled genomes from a male, female and hermaphrodite (unpublished), have identified sex linked scaffolds and have identified paralogues of genes known to be in the sex determination cascade (e.g. doublesex, transformer 2, fruitless) as well as sex-linked genes with interesting sequence differences between males and females [4]

Aims:

1) To understand the gene networks underlying sex determination in dioecious populations of Triops cancriformis.
2) To understand the changes in gene networks in the switch from dioecy to hermaphroditism.

Methods

• Triops will be reared in the lab and sexed using already developed molecular sexing methods.
• Differential expression analysis of genes between known males and females and hermaphrodites using RNAseq analysis and established bioinformatic pipelines
• Specific genes will be knocked down using RNAi to assess function. Success of knockdowns will be determined by expression changes and by phenotype changes.
• Test for location of gene expression using fluorescence techniques (in situ hybridization and immunochemistry).

Eligibility:
UK/EU applicants only.

Entry requirements:
Applicants are required to hold/or expect to obtain a UK Bachelor Degree 2:1 or better in a relevant subject.
The University of Leicester English language requirements apply where applicable: https://le.ac.uk/study/research-degrees/entry-reqs/eng-lang-reqs/ielts-65

How to apply:
Please refer carefully to the application guidance and apply using the online application link at https://le.ac.uk/study/research-degrees/funded-opportunities/bbsrc-mibtp

Project / Funding Enquiries:
Application enquiries to
Closing date for applications: Sunday 12th January 2020

Applications at Aston University

 If you are interested in a PhD project at Aston University, please read the guidance notes and complete the application form.
 From the drop-down options, select School of Life and Health Sciences; October; Full Time; Postgraduate Research; Research Biomedical Sciences (Full Time October 2019). (An option for October 2020 is pending –in the meantime, your application will be updated to 2020 when received).
 Please also notify MIBTP of your application by completing the online application notification form.

References

1. Guerrero‐Tortolero D.A., Campos‐Ramos R. Sex Reversal and Determination and Sex Control in Shrimp and Prawn. In Sex Control in Aquaculture (eds. Wang H.P., Piferrer F., Chen S.L., Shen Z.G.).

2. Kato Y., Kobayashi K., Watanabe H., Iguchi T. 2011 Environmental Sex Determination in the Branchiopod Crustacean Daphnia magna: Deep Conservation of a Doublesex Gene in the Sex-Determining Pathway. PLOS Genetics 7(3), e1001345. (doi:10.1371/journal.pgen.1001345).

3. Li S., Li F., Wen R., Xiang J. 2012 Identification and Characterization of the Sex-Determiner Transformer-2 homologue in Chinese Shrimp, Fenneropenaeus chinensis. Sexual Development 6(5), 267-278.

4. Mathers T.C., Hammond R.L., Jenner R.A., Hanfling B., Atkins J., Gomez A. 2015 Transition in sexual system and sex chromosome evolution in the tadpole shrimp Triops cancriformis. Heredity 115(1), 37-46. (doi:10.1038/hdy.2015.10).

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