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The science challenge

The science challenge

How do animals produce shells?

Our world is changing: our oceans are becoming warmer and more acidic. Understanding the consequences of this is one of the big science challenges of the 21st Century. The oceans of the planet are closely linked with human health and wellbeing, through their impact on climate and their socio-economic importance.. This network will study how shells are produced and controlled in four of Europe’s most important commercial marine shellfish species, oysters, mussels, clams and scallops.

These shellfish have thick shells which are made up of a high percentage of calcium containing compounds. When water becomes more acidic,  the shells dissolve more easily and the shell is also more difficult to make and if this is not corrected will reduce the strength of the barrier between the soft animal and its surrounding environment. Understanding how these animals make shells and regulate shell production in the natural environment is critical to our understanding of how they will fare under climate change. This will improve our ability to predict future shellfish biodiversity and aquaculture production in a rapidly changing world. Also, knowledge of the natural processes by which a soluble compound (calcium) is used to produce robust solid structures (shell) with very little input of energy will also be explored with reference to biotechnology exploitation.

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Natural variation

Natural variation

Shell thickness, shape, size and composition can vary significantly within species, depending on where they live and these are all strongly influenced by the local conditions. Understanding how shell characteristics vary in the natural environment is essential if we are to accurately predict how these animals will be affected when the environment changes. For example, if the sea warms up, will shells be thicker or thinner? We can test this by examining shells in animals from the Arctic, where sea temperatures can vary between freezing in winter and 6-8°C in the summer) and comparing them with animals from off the coast of Portugal (temperatures from 12°C  in winter and summer temperatures of up to 27°C in the lagoon by the research station). By studying the composition of shells from the same species obtained from different environments we can identify how local environmental conditions affect shell production and also identify if there are genetic factors associated with any observed differences. This will enable us to identify potentially resilient populations which can be selectively bred for future aquaculture production.

Scientists in charge

  • Elizabeth Harper (University of Cambridge)
  • Joe Hoffman (University of Bielefeld)

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Shell costs

Shell costs

Throughout its life, a mollusc has to devote considerable amounts of energy to growth (of both shell and body tissue), reproduction and maintenance of essential cellular systems, such as immune functioning. It gets this energy from its food, but how the animal uses this energy  depends on the environmental conditions and time of year. In the winter there is not much food, so little growth occurs. In the summer, although there is much more food, the animal also has to reproduce, which is a considerable drain on energy reserves and the amount of growth is, to a certain extent , dictated by the balance of costs between these two essential activities. Also, if the animal is stressed, as can happen in Scottish lochs with fresh water run-off from pine forests temporarily lowering the salinity and pH of the water,  it will divert energy towards resisting  stress and boosting its immune system. By studying the same species of mollusc in different environments, in both  summer and winter and also manipulating conditions in the laboratory, we will be able to determine how molluscs allocate their energy under different conditions and how this impacts shell growth. This will enable us to better predict, how these animals will respond to our changing climate.

Scientists in charge

  • Lloyd Peck (British Antarctic Survey)
  • Kim Last (Scottish Association of Marine Sciences)
  • Frank Melzner (GEOMAR Helmholtz Centre for Ocean research, Kiel)

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Resilient populations

Resilient populations

Individuals within a population are rarely genetically identical. All are slightly different and this produces variations in their ability to cope when the environmental conditions change. It follows that some animals will be better adapted to life under future climate change conditions than others and therefore identifying these more robust individuals and introducing them into aquaculture breeding programmes would be of considerable commercial benefit. This theme aims to identify how much genetic variability there is in the populations of our chosen species. We will identify genetic factors that may be associated with resistance to, or adaptation to climate change and to carry out selection experiments to identify more resilient strains for future aquaculture production.

Scientists in charge

  • Sam Dupont (University of Gothenburg)

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Shell production

Shell production

Whilst we know a lot about how humans produce bone (which is essentially a mineralised structure, comprising a high percentage of calcium and bound together with a protein matrix), we know very little about how molluscs produce their equivalent structures: shells. Damaging shells via  drilling will allow us to monitor the genes and proteins that are produced during repair. Using this data we will be able to identify the biochemical pathways involved in shell production. Once an understanding of  the critical genes in this process is established, we can begin more targeted analyses to see how they are regulated in different environments and therefore identify potentially important genes in the adaptation to future climate change conditions. Because these biochemical processes, take a soluble form of calcium (in sea water) and turn it into an insoluble compound (shell) without heating or requiring the use of huge amounts of energy, we will explore how these processes may be used in the biotechnology industry.

Scientists in charge

  • Melody Clark (British Antarctic Survey)
  • Arul Marie (Museum National d'Histoire Naturelle de Paris)
  • Karim Gharbi (University of Edinburgh).

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Moving Calcium

Moving Calcium

Calcium is an essential ion in shell production. But we know little about how shells are produced and  have very little knowledge about how calcium is taken up: does it come from sea water and/or food and in what proportions? How is it moved around the body to end up in the shell? How is it controlled?  We will study in detail the tissue in the animal which ultimately makes the shell (the mantle tissue) to identify biochemical pathways involved in mobilising calcium from body tissues to produce the hard structure of the shell and how this is controlled. This will allow us to answer some fundamental questions: Can we induce more or less shell production by manipulating environmental conditions? What hormones are involved and how do they regulate shell production under different conditions? Are there genetic variants of these hormones in different populations which can be exploited in future breeding programmes?

Scientists in charge

  • Deborah Power (Centre of Marine sciences, Portugal)
  • Kristina Snuttan Sundell (University of Gothenburg)


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