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Fecal transplantation has prolonged the fish's life

Anna Kaznadzei, N+1

German researchers from the Institute of Aging Biology for the first time observed the effect of rejuvenation after the exchange of intestinal microflora between small fish, which are called Furzer's notobranchs. The life span of fish eating the feces of their young brethren has increased by more than a third. The work can be read in the preliminary publication on bioRxiv.org (Smith et al., Regulation of Life Span by the Gut Microbiota in The Short-Lived African Turquoise Killifish.

A microbiome is a community of bacteria living in certain environmental conditions, in this case, in the intestine. Such bacteria are symbionts of their hosts, and without them the normal course of digestion is impossible. As a rule, many bacterial species live in the intestine at the same time, making up an entire ecosystem with a certain balance, the shift of which can greatly affect the health of the host. Recently, microbiome studies have become very popular, scientists believe that the role of bacteria in the body is not limited to the digestion of food, but affects almost all of its vital functions, including immunity and even memory and learning ability.

Microbiome transplantation is considered a promising medical development, and helps to cope with such dangerous diseases as pseudomembranous colitis (we have already talked about special fecal banks before), and even with less serious problems, for example, with the smell from the armpits. This kind of treatment is sometimes much more effective and less harmful than the use of antibiotics.

It is known that life expectancy is influenced, in particular, by the temperature of the environment and the nature of the body's nutrition (cold and a small amount of food contribute to its prolongation in some organisms), but, in general, the possibilities to influence this process have not been studied well enough. The well-known difference between the compositions of microbiomes at a young and old age (a significant decrease in the diversity of the composition of microbiomes in old individuals is shown) prompted scientists to think about a possible rejuvenating effect with appropriate transplantation. Previous studies have also shown that restoring the balance of intestinal microflora in dysbiosis, for example, in fruit flies, leads to an extension of their life.

Notobranchs live only a couple of months – a very short period for a vertebrate animal – and therefore are a convenient model organism for studying aging processes.

They are also home to a wide range of microbes at a young age, and by old age they lose most of the diversity of their symbionts. Looking at the composition of the intestines of fish, you can easily determine its age, the researchers note. The decrease in diversity in old age concerns not only the number of bacterial species, but also the contribution of large taxonomic units to carbohydrate, nucleotide and amino acid metabolism. It turned out that representatives of Proteobacteria predominate in old organisms, which are capable of causing dysbiosis, while young forms were distinguished by a variety of Firmicutes, Actinobacteria and Bacteroidetes; in addition, they had better DNA repair systems, which ensures the ability of the microbiome to defend itself and maintain homeostasis. At the same time, old fish differ quite significantly from each other in the composition of the microbiome, and in young fish its composition is more or less the same.

In order to investigate the possible rejuvenating effect of transplantation of the notobranch microbiome or to verify its absence, scientists conducted the following experiment. First, they fed 9.5-week-old fish with antibiotics to destroy their own bacteria, and then placed them in a clean aquarium containing the feces of 6-week-old fish. "Notabranchi usually do not eat feces," notes geneticist Dario Valenzano, project manager, "but they taste everything that resembles food, and therefore microbes will be able to get inside their body." After making sure that the microbes had taken root, the scientists began to observe the further course of fish life. A month and a half later, the composition of their intestinal microflora was still similar to six-week-old individuals, and the studied notobranchs were swimming briskly in the aquarium, unlike their usual peers, for whom such an age is already considered respectable. The life span of the studied notobranchs was extended by an average of 41 percent.

At the same time, the opposite experiment – feeding young fish with the feces of old fish – did not have the opposite effect and did not affect their life expectancy. Previously, similar experiments of "young blood" were carried out, for example, with mice – when two circulatory systems were combined, the older mouse improved its health, and the younger one did not worsen.

Transcriptomic analysis showed that the aging of the intestine of notobranch is associated with an increase in inflammatory processes and a decrease in the processes of proliferation and differentiation of its cells. Researchers believe that with age, the immunity of fish weakens, and more harmful bacteria begin to predominate in the microbiome, and the body is mainly engaged in fighting them, rather than normal functioning, and therefore transplanting young microbiomes can help restore the previous balance and "fix" the intestines. In addition, the young microbiome can somehow influence the the immune system itself. In the future, scientists are going to investigate the relevant mechanisms, as well as try to conduct similar experiments on fruit flies and mice. You can read about how the ovaries of young individuals were transplanted to old mice for rejuvenation purposes here.

Portal "Eternal youth" http://vechnayamolodost.ru  05.04.2017