Study shows tropical fish able to adapt body temperature by environment

Such responses are present in the fish's genes and suggest that a reaction to cold induces an energy-conserving or stress-reduced response.

By YAFIT OVADIA
Updated: NOVEMBER 23, 2018 04:50
Picture of a Blue Tilapia (photo credit: Courtesy)
Picture of a Blue Tilapia
(photo credit: Courtesy)
Researchers at Ben-Gurion University of the Negev revealed that certain species of tropical fish are able to adjust body temperature based on their environment.
The research, which was carried out by Fotini Kokou, a post-doctoral fellow and Itzhak Mizrahi, an associate professor of microbial ecogenomics, discovered that host organisms are affected by the microbes that live within them, suggesting that they possess a symbiotic relationship – each benefiting from the other.
“One of the most significant environmental pressures that affects the fitness of a host organism is temperature,” said Kokou, adding, “We wanted to test whether acclimatization to temperature is facilitated by changes in the host’s microbiome.”
The research used a unique species of tropical fish – the blue tilapia – which exhibit extreme sensitivity to colder temperatures. New higher resistant strains to freezing temperatures were bred. This allowed researchers to compare reactions to stimuli between the sensitive and resistant breeds, and analyze whether it affected the microbes.
Researchers exposed fish with either cold tolerance or intolerance to temperatures of 12 and 24 degrees centigrade. The gut microbiomes of the fish were then examined, showing a large decline in the amount of microbes in either group, who were exposed to the colder temperature. The study discovered that colder temperatures can reduce the amount of microbes in fish. It also found that each fish contained microbes which can either “switch off” during energy expedient processes (such as metabolism), or turn on during times of stress.
The study revealed that such responses are present in the fish’s genes and suggest that a reaction to cold induces an energy-conserving or stress-reduced response. This may explain how certain breeds have survived through the process of natural selection.
“Our study shows that the genetic background of the tilapia fish and its tolerance to temperature-induced stress determines the response of the gut microbiome to temperature,” said Mizrahi. “Microbes and their hosts work together in a survival of the fittest as part of the natural selection process,” he added.


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