Fish poison

Over the years, the poisoned waters of the Hudson River fish okunepodobnye tomkody learned to ignore neurotoxic venoms. So much the worse for their enemies: the accumulated biphenyls, fish oil is very harmful dish.

To industrial progress with the resulting man-made disasters and pollution can be treated differently. "Green" prefer at every opportunity to raise the alarm and to celebrate the memorial service for already extinct species. Environmentalists with decent composure of Buddhism describe changes in climatic niches and open the way for the migration of animals.

As for evolutionary biologists, for them it's difficult to imagine a more interesting decade than the end of XX — beginning of XXI century. After all, right in front of them there are processes that previously could leave hundreds of thousands of years. It's not in the high background radiation, provoke mutagenesis: just in the history of the world flora and fauna are not often faced with the rapid emergence of new ecological niches.

A team of scientists led by Mark Hanna of the legendary Oceanographic Institution Woods Hole found that river pollution polychlorinated biphenyls half a century ago led to the fish in the Hudson, resistant to these compounds sverhtoksichnym.

Heat resistance, dielectric properties and low cost PCB at the time implicitly determined the choice of bases and additives to the insulators, paints, mastics, lubricants and other electrical components. The same physical and chemical properties make the strongest poison PCBs — they are carcinogenic, accumulate in the fatty tissues and are a group of neurotoxins, the mechanism of action of recalling dioxin.

PCBs bind to the transcription factor AHR, supervising the work of other genes that play a key role in the development of the organism, cellular respiration, synthesis and transport of hormones.

In tomkodov resistant biphenyls referred AHR protein is mutated — it lacks two of 1104 amino acids.

As a result, it is less associated with the PCB to minimize toxic effects. And its core functions, mutations do not interfere with fish: tomkody thrive in nature and in captivity.

To the delight of the authors published in Science, is the first example of a quick "resistance mutations" in vertebrates. Usually by this more likely of rapidly bacteria and fungi, only as a factor of selection they have not acting chemical contamination, and another antibiotic.

Mutated individual receives a distinct advantage and quickly fills the ecological niche.

Typically, these genetic changes occur during sexual reproduction (the formation of gametes), some of them will have no effect on the protein, often leads to anomalies that are not compatible with life, and some, as in this case, allow their owners to be fruitful in quite unsuitable for the conditions.

Moreover, resistance to chemicals and is combined with the ability to control the number of predators, because PCBs are stored in the fatty tissue of fish, so eating their predators (including people) Inevitably get a decent dose of poison.

Despite the lack of visible differences, "mutants" in some ways still lose the general population Microgadus tomcod. In less polluted rivers that flow into the Atlantic Ocean north of the Hudson, the main population continues to dominate. Although in this region from 1946 to 1970, General Electric factories dumped 600,000 tons of biphenyl. The authors suggest that this may be due to increased sensitivity to other polluting compounds, in particular to polyaromatic hydrocarbons.

Maybe you just have to wait for another half a century, and we will see fish mutants, ready to face any chemistry. The main thing — do not pour into the river too much naphthalene.

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