This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The NERC GW4+ DTP involves the four research-intensive universities across the South West – Bath, Bristol, Cardiff and Exeter â and six Research Organisation partners. For further details about the programme please see the Apply button below.
Studentships will be awarded on the basis of merit and will commence in September 2014. For eligible students the award will cover UK/EU tuition fees and an annual stipend (in 2013/14 this was £13,726 for full-time students, pro rata for part-time students) for four years.
Supervisors:
Dr Eduarda Santos, College of Life and Environmental Science, University of Exeter
Dr Ioanna Katsiadaki, Centre of Environment, Fisheries and Aquaculture Sciences
Dr Ronny van Aerle, College of Life and Environmental Science, University of Exeter
Prof Jonathan Mill, Exeter Medical School, University of Exeter
Project description: In lower vertebrates, including fish, the molecular events regulating sex determination and coordinating the sexual development of the germ cells remain poorly understood, despite their fundamental importance. It is well known that environmental factors including photoperiod and temperature strongly regulate these events, but the exact mechanisms by which they modulate sex determination and development pathways are unclear. We hypothesise that this regulation is mediated, at least in part, via epigenetic mechanisms including regulation of transcription via methylation of DNA and regulation of translation via microRNAs (miRNAs). This studentship will investigate this hypothesis and determine the role of epigenetic modifications on sex differentiation, development and maturation in a model fish species, the three-spined stickleback (Gasterosteus aculeatus). This species combines all advantages of laboratory model species (i.e. small size, short life span, sequenced genome) and sentinel species (annual reproductive cycle, strong circannual rhythm).
Objectives
1 â Elucidate the transcriptomic profiles and epigenetic regulation of key genes involved in sexual development during the reproductive cycle.
The student will characterise the ontogenic development of the gonads (histopathology) and the physiological changes that accompany this process in three-spined stickleback by measuring plasma sex steroid, vitellogenin and kidney spiggin levels. The expression of key target genes involved in sex differentiation and development, as well as genes regulated by photoperiod and involved in the regulation of reproduction will be measured in the brains, pituitaries and gonads using qPCR. DNA methylation across regulatory regions of these genes will be determined using bisulfite-pyrosequencing. Gonadal miRNAs will be identified and profiled by sequencing to determine miRNAs that associated with key sex development events. Data will be integrated to determine the regulatory events regulating sex differentiation and development in this species. All methodologies are already established at the supervisorsâ labs, therefore involving limited or no risk.
2 â Determine the role of temperature and photoperiod on the regulation of sexual development and the molecular mechanisms mediating these effects.
Environmental conditions (photoperiod and temperature) will be manipulated in order to alter the timing of sexual development and maturation, providing an opportunity to understand the regulation of the cascade of events leading to sexual development and maturation. The mechanisms triggering these events will be documented for the molecular, biochemical and histological levels, as above. This will be done for temperature and photoperiod independently and in combination, to determine the independent and combined influence of these two factors on the onset of maturation in this species.
The closing date for applications is midnight Friday 10 January 2014. Interviews are expected to take place in February.