The Scientist November 2019

tain microbial populations take a long
time to establish after permafrost thaw,”
he explains. “Methane producers, for
instance, seem to be very sensitive to freez-
ing.” Based on his team’s lab results, Gra-
ham and colleagues predicted that a long
stretch of warmer temperatures would
allow a large population of methane-
producing microbes to grow—just as
Schuur, Johnston, and their colleagues
found. “It’s neat to see these kinds of
[microbial] behaviors happening in the
lab and all the way to the field.”
Although the current study identified
the genes present in the microbial com-
munity, it couldn’t detect which of those
genes were producing proteins. “One of
the critical [next] steps is understand-
ing which genes are actually expressed:
Which organisms are working hard,
and what are they doing?” Graham says.
“Another critical question is: What are
they actually consuming?” The research-
ers note in the paper that the plant com-

munity in the experimental plots is

becoming more abundant as a result of

the insulation experiment. Plants can

contribute fresh carbon to the soil for

microbes to decompose, in addition to

the older carbon already stored in the

permafrost. Distinguishing between the

two carbon sources is important, John-

ston says, because if all of the carbon

being metabolized by microbes is from

fresh plant material, the resulting fluc-

tuations in atmospheric carbon dioxide

levels will be relatively minimal. On the

other hand, “if old carbon that has been

locked up for hundreds or thousands of

years is being respired, this will cause a

long-term increase in the concentration

of carbon dioxide in the atmosphere.”

Schuur is starting to tackle these

questions. In another paper published in

July, he and his colleagues reported that,

when analyzed together, the insulated

and the uninsulated plots of soil lost an

average of 5 percent of their stored car-

bon per year over five years, suggesting

old carbon is indeed being used by res-

ident microbial communities. Based on

atmospheric warming predictions, that

translates to permafrost losing up to 78

percent of carbon in its top 55 centime-

ters by the end of the century ( Nat Geosci,

12:627–31, 2019).

The researchers note in their paper

that they still need to see if the results hold

true in other plots of permafrost around

the Arctic, but the findings suggest per-

mafrost warming will lead to significant

greenhouse gas emissions, they conclude.

“There is increasing recognition that the

processes of soil microorganisms, and

their responses to rising temperatures,

need to be better incorporated into cli-

mate models in order to improve the accu-

racy of climate predictions,” Johnston says.

“Research like this provides information

for other researchers tasked with improv-

ing these models.”

—Ashley Yeager

Establishing research models for any human disease is tricky business—more so for rare genetic diseases such as ataxia, telangiectasia, progeria, Paget’s

disease, and Rett syndrome. Researchers who study model organisms such as  Caenorhabditis elegans, Drosophila, mice, zebrafish, and yeast rarely connect

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bringing together a panel of experts to share their research, and to highlight the challenges and advantages of utilizing specific model organisms. Attendees will

learn how model organisms can help scientists parse complex mechanisms underlying rare genetic disease from renowned experts in our interactive setting.

MONICA JUSTICE, PhD

Program Head and Senior Scientist

Genetics & Genome Biology Program,

SickKids Research Institute

Professor of Molecular Genetics,

University of Toronto

Scientific Director,

The Centre for Phenogenomics

Rare Genetic Disease:

Models and Mechanisms

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TUESDAY, NOVEMBER 19

2:30 - 4:00 PM EASTERN TIME

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http://www.the-scientist.com/modeling-rare-genetic-diseases

The webinar video will also be available at this link.

SHAWN BURGESS, PhD

Senior Investigator

Head, Developmental Genomics Section

National Human Genome Research Institute

National Institutes of Health

TOPICS TO BE COVERED:

• Modeling Rett syndrome using mice


• Tanks to bedside: examples of disease modeling in
  zebrafish