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The amount of DNA in the nucleus of a cell is commonly referred to as the genome size or C-value and scientists have been measuring this character in plants and animals for over 60 years. The C-value of an organism reflects the number of nitrogen and phosphorus atoms needed to build the DNA of every cell. Nitrogenous bases by mass are approximate 39% nitrogen (N, assuming a 1:1 ratio for purines and pyridines)(Sterner and Elser 2002) and nearly 9% phosphorus (P). Thus it is costly to build nucleic acids. Despite that cost, there is an astonishing 2,400-fold range in the C-values of angiosperms, the largest range of any eukaryotic group; with the smallest angiosperm reported being Genlisea aurea (1C = 0.0648 pg) and the largest angiosperm, indeed eukaryote is Paris japonica with a staggering 1C value of 152.3 pg DNA in each cell.
You will test the hypothesis that there are ecological costs to possessing large genomes, because of the higher investment into nucleic acids, which poses particular demands for the assimilation of phosphates and nitrates. You will determine whether available nutrients influence (i) the occurrence, distribution and abundance of plant species depending on their C-values; (ii) the abundance of polyploid species, i.e. those species where the genomes occur in multiple sets; and (iii) the amount of total C, N and P bound up in the plant biomass.
(i) Data acquisition and analysis. Large datasets already exist showing (i) plant distributions, (ii) C-value measurements, (iii) plant ploidy levels, (iv) angiosperm phylogenies, and (v) canopy heights. You will source these data and obtain new data, and organize them into relational databases so that you can derive new information and insights.
(ii) Field-work. You will need to source new knowledge of C-values and ploidy levels at particular field sites. This will require training in fieldwork skills, e.g. collecting, vouchering and site recording.
(iii) C-value measurements. You will need to obtain new chromosome and C-values measurements and thus you will need to obtain skills in cytogenetics and flow cytometry.
(iv) RNA, DNA and bioinformatics. You will compare DNA:RNA ratios in plants varying in C-value, ploidy level and ecology. From a selection, you will use Next Generation Sequencing approaches to study the nature of the genome and transcriptome.
Qualifications: You should have at least an upper-second class honours degree in an area relevant to the project.
To apply: please complete an online application form via the following link: http://www.sbcs.qmul.ac.uk/prospectivestudents/research/howtoapply/index.html.
Informal enquiries: these should be directed to a.r.leitch@qmul.ac.uk (+44 (0) 20 7882 5294) or i.leitch@kew.org (+44 (0) 20 8332 5329)
The Leitch Lab webpage: http://webspace.qmul.ac.uk/arleitch/Site/Home.html
Funding Notes:
This studentship forms part of NERC and Norwegian Research Council funded projects and covers fees, and an annual stipend at the Research Council level of £15,590, which includes London Allowance.
References:
Leitch and Leitch 2008 (Science 320: 481-483) and Leitch and Leitch 2012 (New Phytologist 194: 629-646)