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PhD: How do marine virus puppets affect ocean photosynthesis?

Primary Supervisor: Professor Dave Scanlan (University of Warwick)

Secondary supervisors: Dr Richard Puxty (University of Warwick) and Dr Andrew Millard (University of Leicester)

Start date: October 2021

Funding: Tuition fees will be paid at the Home/EU tuition fee level. An annual (tax free) stipend of at least £15,285 will be paid for 4 years.

Application deadline: 15 January 2021

Project outline:

The oceans play a major role in determining world climate via the production of oxygen and the consumption of carbon dioxide largely by tiny, single celled organisms, the photosynthetic picoplankton. These organisms, which are numerically dominated by the cyanobacterial genera Prochlorococcus and Synechococcus can be responsible for up to 70% of CO2 fixation in some oceanic regions [1]. Marine cyanophages, viruses infecting both Synechococcus and Prochlorococcus [2], appear to be extremely abundant (up to 106 ml-1 [2]) in most aquatic ecosystems, and a key current question is to what extent viruses drive the structure and function of these marine picophytoplankton communities, and in so doing dictate the fate of fixed carbon.

Cyanophages are exceptional in that they also appear to play a direct role in CO2 fixation since they carry genes that are essential for photosynthesis [3, 4, 5]. The phage derived copies of psbA encoding core photosystem II reaction centre proteins are thought to maintain cellular photosynthetic activity during infection thus maximizing the production of progeny phage. The viral psbA gene is an example of an auxiliary metabolic gene (AMG) carried by the phage. Other AMGs include various components of the photosynthetic machinery and central carbon metabolism. Understanding how cyanophage AMG carriage is affected by the actual environment the phage inhabits is a key question that will help unlock the role and selective advantage of carrying these AMGs under specific conditions and will be facilitated by isolating phage from a research cruise transect obtained in the Atlantic Ocean.

In addition to environmental control on AMG carriage, AMG fitness landscapes may be shaped by specific hosts that each phage infects. However, our understanding of the determinants of host range are poor. In the first instance, phages must adsorb to their host using the combination of a host receptor and a phage receptor binding protein. These are likely primary genetic determinants of host range, yet we have no idea what they are! Using cutting edge genetic approaches this PhD project can also then elucidate both the phage tail fibres and host receptors and facilitate a molecular understanding of the viral-host arms race.

The project will provide excellent training in a range of molecular biological, biochemical & microbiological techniques. The student will benefit from the wide array of scientific expertise already available in the host labs.

This exciting project funded as part of a large Advanced European Research Council (ERC) grant represents a fantastic opportunity to greatly advance our understanding of lytic phage-host interactions whilst, at the same time, developing a range of research skills.

References:

  1. Jardillier L et al., (2010) ISME J 4 : 1180-1192.
  2. Mann, NH (2003) FEMS Microbiol Rev 27 : 17-34.
  3. Mann, NH et al. (2003) Nature 424: 741.
  4. Millard A et al. (2004) PNAS 101: 11007-11012.
  5. Clokie, MRJ et al (2006) Env Microbiol 8: 827-835.
  6. Millard A et al. (2010) ISME J 4: 1121-1135.

Key experimental skills involved: Cutting-edge molecular and microbiology techniques, e.g. transcriptomics, proteomics, microbial physiology and analytical photosynthetic skills e.g. PAM fluorometry.

Eligibility

The University’s standard entry requirements are as follows:

  • You must hold an upper second class UK honours degree (2:1) in Microbiology/Biochemistry with a particular interest in analytical and computational techniques or equivalent qualification.
  • You must be able to provide 2 satisfactory academic references
  • Submit an English Language test certificateLink opens in a new window (if appropriate). Please note: It is a requirement that overseas students will show that their ability to understand and express themselves in both written and spoken English is sufficiently high for them to derive the full benefit from the PhD. Please note that the requirement for admission is IELTS 6.5 (with no component below 6.0) or equivalent. More information can be found at:

http://www2.warwick.ac.uk/study/postgraduate/apply/english/

How to apply

  • Informal project enquiries can be made to Prof Dave Scanlan , Dr Rich Puxty or Dr Andrew Millard . For further details of research in the supervisors labs see http://www2.warwick.ac.uk/fac/sci/lifesci/people/dscanlan, https://warwick.ac.uk/fac/sci/lifesci/people/rpuxty/ and https://millardlab.org/.
  • Complete the online application formLink opens in a new window - selecting course code: P-C1PB - PhD Life Sciences
  • Upload a transcript from your current or previous study and any other documents that you feel would support your application.
  • Ask your referees to submit a reference for you. Note: when you submit your application, an email will automatically be sent to your referees requesting a reference for you. This email will contain a secure link for your referee to upload a reference for you.
  • The deadline for applications is 15 January 2021

For further information about applying to Warwick see the application FAQ'sLink opens in a new window page”