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Adaptations to temperature regimes in sponges: Genomic insights into the developmental and physiological evolutionary changes of early-branching metazoans

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Finding secrets to life in the world’s most extreme marine environments

Studying the genetic adaptations of sponges living in polar waters could help us better understand what mechanisms they use to survive

Climate Change and Environment

Even in the harsh conditions of Antarctica and the Arctic, life has found a way to survive. Marine creatures have evolved ways to cope with water temperatures ranging from freezing point to -2 °C, with food also often hard to come by. There must be some underlying genetic adaption and finding out more about molecular adaptations could be useful for future commercial applications, such as protecting vehicles from extreme cold. The ADAPTOMICS team, backed by the Marie Skłodowska-Curie programme, embarked on a mission to uncover these natural secrets in organisms at both of the planet’s poles. “Our goal was to understand the molecular adaptations of sponges that allow them to live in extremely cold temperatures, like those in Antarctica, comparing Antarctic sponge genomes and transcriptomes to those of their counterparts in temperate and tropical regions,” says Dr Ana Riesgo from the Natural History Museum in London and ADAPTOMICS project coordinator. “In particular, we were looking at whether independent species of sponge had the same responses to cold conditions, or evolved completely different mechanisms to deal with them,” explains Dr Nathan Kenny, MSCA fellow and the project’s lead researcher.

Sourcing the specimens

Dr Riesgo travelled to Antarctica, diving beneath the sub-zero waters to collect sponges for study. “It was very challenging because of the extreme cold and the very bulky equipment we had to wear, but also extremely rewarding, since what you see underwater there, very few people in the world have seen before,” Dr Riesgo says. Dr Kenny travelled up to the Arctic Circle, sampling deep sea waters from aboard a boat. The most challenging aspect of the project was gaining access to fresh samples when back home. “While we were fortunate to have great collaborators in Chile who had the samples, it was not easy to arrange the inter-continent freight!” says Dr Kenny. Back in London, the team performed multiple analytical sequencing techniques on the hardy sponges. They sequenced the genomes of six different species, before performing transcriptomic analyses (reading between genetic lines) and applied a technique known as RNA in situ hybridisation to home in on certain portions of the genetic data.

Diving into the data

After much analysis, the researchers found that in some of the specimens, similar genes had been altered – a process known as ‘convergent evolution’, where organisms evolve the same trait separately. However, there were also many examples of unique sponge adaptations, too. “The most striking result was how normal many of the genes that changed were. While it would have been fun to see a ‘master control’ gene for Antarctic adaptation, what we found instead was that many of the ‘housekeeping’ genes that perform the basic roles necessary for survival, were the ones implicated,” Dr Kenny explains.

Future prospects

“We would like to highlight the great opportunity that MSCA gave us to explore how nature works in remote and extreme environments. It was really a trailblazing experience,” Dr Riesgo says. The project paves the way for large-scale comparative genomic analysis, to further understand cold adaptation strategies in other animals and across different locations on the planet. “There is a lot left to learn about Antarctica, and the weird but wonderful creatures that live there!” says Dr Riesgo.

Keywords

ADAPTOMICS, extreme, life, Antarctic, Arctic, polar, genes, survive, mechanism

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