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  Re: [Aroid-l] OT: Fungi that eat ionizing radiation?
From: Ron Kaufmann <kaufmann at sandiego.edu> on 2007.05.24 at 20:34:32(15705)
Hi Steve,

The melanin story is very interesting, and if it's true that
melanin changes in response to ionizing radiation exposure and may
facilitate survival of organisms under conditions that otherwise might
be lethal, the repercussions could be many and far-reaching. Cool

As for the National Geographic special, I'd like to address a few
factual issues in what you wrote. First, there are *many* areas of the
ocean where hydrothermal vents are spewing hot, mineral-rich water into
the deep sea. The existence of biological communities around many of
those vent sites has been known for 30 years, and many vent communities
and organisms have been studied extensively. The word "noxious" to
describe some of the chemicals that are released by vents is somewhat
human-centered. For example, many organisms that live in anoxic
conditions might describe oxygen as "noxious". :-) Second, the
communities around deep-sea hydrothermal vents are indeed supported by
primary producers (mostly bacteria) that use "noxious" hydrogen sulfide
or methane as energy sources. It's a fascinating system that prior to
30 years ago would have been considered science fiction!

Finally, the issue of organisms living in nearly 800 degree
Fahrenheit water was a subject of controversy among the biologists who
first studied the vent systems. The deep sea is, for the most part,
very cold (1-2 deg C = 34-36 deg F), and it turns out that temperature
gradients near hot vents are *extremely* steep. The water coming out
of a vent may approach 800 deg F (over 400 deg C) at the hottest sites,
but a few inches away the temperature may be a relatively mild 125-160
deg F (50-70 deg C). Most hydrothermal vent organisms seem to live on
the fringes of the hot water plume, not within the hottest water.

Ron Kaufmann

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