Molluscs’ sense of self underscores fundamental study

In the gemstones industry, the production of cultured pearls depends on a biological quirk – the ability of tissues from different individuals to fuse together. 

Cultured pearl formation relies on shell-forming tissue from a donor oyster being grafted into a second oyster. 

The grafted tissue grows to form a pearl sac, with the new pearl secreted inside. The grafted tissue is rarely, if ever, rejected. 

In almost all species, the innate ability to distinguish their own cells from those of others helps to detect the threat of disease, to recognise food and to avoid predating their own kind. 

This quality appears to be impaired in oysters and also in mussels – and now scientists hope to discover why.

Researchers are to examine this interesting property of molluscs to better understand the biology of allorecognition - the critical process that multicellular organisms use to distinguish their own cells from those of others, which has important implications for evolution.

New knowledge could potentially impact breeding programmes aimed at enhancing disease resistance, by allowing scientists to select for useful genes. 

“This unusual trait provides a perfect model system in mussels to better understand the genetic and molecular bases of allorecognition processes,” explains Dr Tim Regan, who is co-leading the three-year project, led by Carmel McDougall of the University of St Andrews, and funded by the Biotechnology and Biological Sciences Research Council.

Scientists from Roslin and St Andrews University, and colleagues in Montpellier, France, will collaborate to determine the biological factors that influence the ability of mollusc cells to distinguish themselves from cells of another organism from the same, or different species. 

They will aim to determine which genes are involved, in tissues within the same individual, between different individuals of the same species, and across different species. 

They will also compare genes in shellfish with those of organisms on other branches of the tree of life.

Roslin will bring expertise in bioinformatics to the project, which has implications for fundamental biology.

Mollie Stefanek, postgraduate researcher at the University of St Andrews, said: “Preliminary results show that closely related species do not have a clear rejection response, and we are interested in exploring how genetically different material needs to be to elicit a reaction, what mechanisms are involved, and if they are the same as disease resistance responses."

Insights from this study could transform scientific understanding of disease mechanisms across various animal groups.

These findings could also offer vital contributions to biosecurity and public health strategies, which are important for managing health in wild and cultivated animal populations.

Researchers hope the project will represent an essential step forward in the understanding of fundamental biological processes, and their practical applications for disease management and environmental health. 

Image credit: Carmel McDougall