The common Eurasian shrew shrinks its “fuel-guzzling” organs to survive. You lose up to 18% of your weight. The phenomenon may be related to the treatment of human diseases.
Some animals, such as bears, increase their body mass to survive the cold, making their adipose layer grow. But the Eurasian shrew (Sorex araneus), does exactly the opposite — with the same objective.
This small mammal reduces the size of its organs that consume the most “fuel”, that is, energy, namely the brain, to face external temperatures.
This cunning survival trick is called “Dehnel phenomenon”named after Polish zoologist August Dehnel, and can make the small mammal weighing 5 to 12 grams lose up to 18% of your weight as the temperature drops — a reduction that includes more than a quarter of brain mass — only to regrow the lost tissue the following spring, says Science Alert.
Now, a new study published in November has found a series of genes responsible for the phenomenon, identifying intriguing connections with genetic changes in humans implicated in a variety of health conditions, including Alzheimer’s disease.
The new findings come just a year after they listed a series of metabolic changes in the shrew’s liver, cerebral cortex and hippocampus that accompany seasonal shrinkage, discoveries they say could have implications for the treatment of neurological diseases in humans.
In this study, the team sought to better understand the evolution of Dehnel’s phenomenon, comparing the Gene expressions in the shrew hypothalamus with those of 15 other mammal species from several different orders.
“We generated a unique data set, with which we were able to compare the shrew’s hypothalamus between seasons and species”, says American evolutionary biologist William Thomas. “We found a set of genes that change over the seasons and are involved in the regulation of energy homeostasisas well as genes that regulate cell deathwhich we propose is associated with reductions in brain size.”
By comparing the regulated sequences with similar genes in different mammalian species, the team identified five genes that he considers important for the evolution of Dehnel’s phenomenon in the shrew.
These include a gene that recycles membrane proteins, another that mediates functions of synapse membranes in nerve cells and one linked to obesity and Alzheimer us humans.
Ongoing medical research is increasingly finding significant overlaps between a drop in metabolism and neurodegenerative diseases.
So can this unknown mammal provide more information about the diagnosis and treatment of cognitive decline?
