Biography

Role

Doctoral Researcher & Graduate Teaching Assistant

I am conducting research as a postgraduate student in the lab of Dr Hideo Tsubouchi. The aim of my research is to elucidate the relationship between homologous recombination and cell cycle progression in meiosis. I also provide practical and theoretical assistance to undergraduate students in the School of Life Sciences via laboratory demonstrations and tutorials.

Qualifications

BSc from Queen Mary, University of London

Homologous Recombination

Homologous recombination, HR, is the genetic process whereby two or more DNA sequences that share sequence identity are "reshuffled". This intriciate process plays important roles in both meiosis and DNA repair.

The key focus of meiosis is to halve the ploidy level of the cell. In humans, each somatic nucleated cell contains two sets of chromosomes, one from each parent (hence the ploidy level is denoted as 2n). Prior to the onset of meiosis, these chromosomes are replicated, meaning that there are essentially four sets of chromosomes. During meiosis, these chromosomes are segregated twice, to produce cells containing only one set of chromosomes (1n). These cells are called gametes, and in humans correspond to sperm and eggs. Following fertilisation, the newly formed embryo will therefore have the cannonical two sets of chromosomes (one from the sperm and one from the egg).

In order for chromosomes to separate with such accuracy, they are subjected to several highly specialised processes. Chromosomes that have originated from a recent common ancestor and share significant sequence identity (i.e., homologous chromosomes) pair up, or synapse, to form homologous chromosome pairs. These pairs are known as bivalents. Bivalent formation is a prerequisite of homologous recombination, since for two strands of DNA to be exchanged, the chromosomes on which the DNA is located need to be in close proximity to each other. In order to initiate recombination, the double helix is broken on one of these closely associated chromosomes. These breaks are known as double strand breaks, or DSBs. We have always been taught that DNA is an incredibly stable structure and this is one of the characteristics that has resulted in the selection of DNA as a chemical instruction for the transmission of heredity information. Thus, it seems counter-intuitive that the cell would risk the integrity of its DNA. However, if we consider that homologous recombination is essential for the faithful segregation of chromosome, it is clear that the ends justify the means.

There is a layer of regulation which acts to ensure that chromosomes still carrying breaks do not proceed to form gametes, since these gametes would almost certainly be inviable. This layer of regulation is of particular interest to me and it is often referred to as the recombination checkpoint. Checkpoints essentially ensure that a late event does not take place before the completion of an earleir event. The recombination checkpoint ensures that cells do not commit to chromosome segregation until homologous recombination has taken place, since homologous recombination repairs chromosome breaks through a pathway that promotes the exchange of DNA strands between homologous chromosomes. This particular pathway is absolutely critical for the accurate segregation of chromosomes.

2012-2013

Microbiological Methods, lab demonstrations

Molecular Biology, lab demonstrations and tutorials

2011-2012

Clinical Aspects of Biochemistry, lab demonstrations

Darwinian Evolution, tutorials

Introduction to Microbiology, lab demonstrations

Introduction to Molecular Genetics, lab demonstrations

Medical Microbiology, lab demonstrations

Research Methods in Biochemistry, lab demonstrations

Student Consultation

24/7 via email (response may be slow during particularly busy periods)

Humphryes, Neil, Leung, Wing-Kit, Argunhan, Bilge, Terentyev, Yaroslav, Dvorackova, Martina and Tsubouchi, Hideo (2013) The Ecm11-Gmc2 complex promotes synaptonemal complex formation through assembly of transverse filaments in budding yeast. PLoS Genetics, 9 (1). e1003194. ISSN 1553-7390

Farmer, Sarah, Hong, Eun-Jin, Leung, Wing-Kit, Argunhan, Bilge, Terentyev, Yaroslav, Humphryes, Neil, Toyoizumi, Hiroshi and Tsubouchi, Hideo (2012) Budding yeast Pch2, a widely conserved meiotic protein, is involved in the initiation of meiotic recombination. PLoS ONE, 7 (6). e39724. ISSN 1932-6203