How does life survive in conditions of extreme temperatures?

When temperatures reach extreme levels, organisms’ adaptation is usually slow and gradual (Getty Images)

Life is a chemical process Temperature is a decisive factor. You can see its effects in all of biology. It is interesting that scientists look at it from an evolutionary perspective. The history of life in relation to temperature has been debated since the appearance of the first trees, suggesting that development May intertwine with temperature.

Despite its major role in biological processes, until today specialists do not have a complete understanding of Adaptation in temperature. To try to solve this question, a research team led by Paula Brondzynski and Sean Erin McGlynn of the Terrestrial Life Sciences Institute (ELSI) at the Tokyo Institute of Technology recently investigated a group of organisms called methanogens. Their results have just been published in the journal DNA Research, which he edits Oxford university.

the methanogens They are single-celled methane-producing microbes that are part of the “archaea” (ancient single-celled organisms that do not have a nucleus and are thought to have been the ancestors of cells). Methanogens are the ideal organisms to investigate temperature adaptation, as they can survive a wide range of temperature extremes, from -2.5 degrees up to 122.

Scientists analyzed and compared the genomes of different methanogens (iStock)

They divided the methanogens into three groups based on the temperatures at which they thrived: the heat (high temperatures), Psychological (low temperatures) f mesophiles (ambient temperatures). Then they used the genome taxonomy database to generate another 255 genome and protein sequences. Then they did the same thing with a database of normal and rare prokaryotic growth temperature to obtain temperature information for 86 methanogens stored in the lab collections. The result is a database link file Genome content with growth temperature.

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Later, the scientists used a program called OrthoFinder to create different orthologs: groups of genes descended from a single gene in the species’ most recent common ancestor. Next, they divided these orthologous groups into three categories: basic (found in more than 95% of species), common (found in at least two species but less than 95% of organisms), and unique (found in only one). ). ). According to his research, all animals share about One-third of the methanogenic genome. They also found that as evolutionary distance increases, the proportion of genes shared by different species decreases.

Interestingly, scientists discovered that heat resistant objects They have smaller genomes and a higher proportion of the primary genome. Moreover, the lifespan of these small genomes was found to be greater than that of psychosis-tolerant species. These results indicate that genome size depends more on temperature than on evolutionary trajectory because heat-tolerant species have been detected in several groups. They also argue that rather than shrinking as methanogenic genomes evolved, they increased, contradicting the thermogenome theory of evolution, according to which organisms lose genes as they adapt to higher temperatures.

Genomes were so important to the investigation that the researchers discovered that the size of the genome depends more on temperature than on the course of evolution.

The researchers’ analyzes also revealed that methanogens can thrive in a wide temperature range without needing many unique proteins. In fact, their genomes are coded for proteins similar to most of them. They speculate that the underlying mechanism of temperature adaptation could be cellular control or compositional modifications on a smaller scale. They investigated this through composition analysis Amino acids of methanogens, which are the building blocks of proteins.

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They discovered that some combinations of temperature were impregnated in some amino acids. In addition, they found differences in the composition of amino acids, which affects the structure of the protein, and therefore its functionality. They found that, in general, thermotolerant methanogens had more charged amino acids and functional ion transport genes than psychotolerant ones. In turn, they have an abundance of proteins and uncharged amino acids that are essential for structure and function. cell movement.

The fact that scientists have not been able to identify any particular role shared by each member of the temperature group indicates that adaptation to temperature occurs gradually and in small steps rather than requiring drastic changes. Paola Brondzynski, one of the paper’s lead authors, explained: “This suggests that early methanogens, which evolved when conditions on Earth were hostile to life, perhaps they were similar to organisms on Earth today. Our findings could indicate traits and functions present in early microbes and even provide clues about whether microbial life arose in environments warm also cold. We can extend this knowledge to understand how organisms can adapt to other types of extreme conditions, not just temperature, and even reveal how life has evolved on other planets.”

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Aileen Morales

"Beer nerd. Food fanatic. Alcohol scholar. Tv practitioner. Writer. Troublemaker. Falls down a lot."

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