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Investigation of intergenic influence on some nitrogen fixation nif operons in Trichodesmium erythraeum IMS101

Polgar, Randall (2012) BIOP01 20112
Degree Projects in Biology
Abstract
The Influence of Intergenics in an Important Environmental Cycle

As we step forward into the future there is increasing attention toward our impact
on the planet and specifically of late debate, our climate. With the carbon dioxide (CO2)
in our atmosphere rising at a quick pace and the ocean’s acidity increasing, largely due to
the industrial revolution, what environmental influences will we be living with and what
effects will they have on us? To examine some of these potential changes we take a
small-scale approach to a global concern.
The most important nitrogen fixer in the open ocean is the cyanobacteria called
Trichodesmium erythraeum IMS101. In ‘fixing’ nitrogen, they turn incredible yields of
unusable nitrogen into... (More)
The Influence of Intergenics in an Important Environmental Cycle

As we step forward into the future there is increasing attention toward our impact
on the planet and specifically of late debate, our climate. With the carbon dioxide (CO2)
in our atmosphere rising at a quick pace and the ocean’s acidity increasing, largely due to
the industrial revolution, what environmental influences will we be living with and what
effects will they have on us? To examine some of these potential changes we take a
small-scale approach to a global concern.
The most important nitrogen fixer in the open ocean is the cyanobacteria called
Trichodesmium erythraeum IMS101. In ‘fixing’ nitrogen, they turn incredible yields of
unusable nitrogen into useable nitrogen as food source. In short-term studies, scientists
have shown that growing Trichodesmium with a higher amount of atmospheric CO2, an
amount predicted in the year 2100 which is more than double today’s current amount,
they are efficient in turning over more usable nitrogen. Unfortunately, how can studies
spanning but a few weeks predict changes over years and decades? Will the trends
continue?
For three years, about 360 generations, we grew Trichodesmium under the current
atmospheric CO2 and under the predicted atmospheric CO2 in the year 2100. We can call
them, “Treatment one” and “Treatment two,” respectively. Then for one week we
switched the Trichodesmium cultures growing in these treatments. We now have four
different treatment types: the current CO2, the future predicted CO2, the current CO2
switched to the future predicted CO2, and finally the future predicted CO2 switched to
grow at the current CO2 concentration. We then sequenced the Trichodesmium growing
in each of the different treatments and compared the genetic expression of the nitrogen
fixation.
In our long-term study, we found an increase in the nitrogen fixation genetic
expression when Trichodesmium was grown under higher concentrations of CO2. We
also saw an inverse effect where the intergenic regions just upstream of the nitrogen
fixation genes were generally down-regulated under higher CO2 and up-regulated at
lower CO2 levels. As the intergenic regions tended to show a coupled effect with their
complemented genic regions, we deduce that these intergenic regions can affect and even
repress the genic regions. This being the case, we can further explore the sequences and
structures of these intergenic regions amongst other nitrogen fixing cyanobacteria and
potentially propose novel non-coding RNAs.

Advisor: David Hutchins
Master´s Degree Project, 60 credits, 2012
Department of Marine Environmental Biology, University of Southern California (Less)
Please use this url to cite or link to this publication:
author
Polgar, Randall
supervisor
organization
course
BIOP01 20112
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3616055
date added to LUP
2013-03-22 11:27:49
date last changed
2013-03-22 11:27:49
@misc{3616055,
  abstract     = {The Influence of Intergenics in an Important Environmental Cycle

As we step forward into the future there is increasing attention toward our impact
on the planet and specifically of late debate, our climate. With the carbon dioxide (CO2)
in our atmosphere rising at a quick pace and the ocean’s acidity increasing, largely due to
the industrial revolution, what environmental influences will we be living with and what
effects will they have on us? To examine some of these potential changes we take a
small-scale approach to a global concern.
The most important nitrogen fixer in the open ocean is the cyanobacteria called
Trichodesmium erythraeum IMS101. In ‘fixing’ nitrogen, they turn incredible yields of
unusable nitrogen into useable nitrogen as food source. In short-term studies, scientists
have shown that growing Trichodesmium with a higher amount of atmospheric CO2, an
amount predicted in the year 2100 which is more than double today’s current amount,
they are efficient in turning over more usable nitrogen. Unfortunately, how can studies
spanning but a few weeks predict changes over years and decades? Will the trends
continue?
For three years, about 360 generations, we grew Trichodesmium under the current
atmospheric CO2 and under the predicted atmospheric CO2 in the year 2100. We can call
them, “Treatment one” and “Treatment two,” respectively. Then for one week we
switched the Trichodesmium cultures growing in these treatments. We now have four
different treatment types: the current CO2, the future predicted CO2, the current CO2
switched to the future predicted CO2, and finally the future predicted CO2 switched to
grow at the current CO2 concentration. We then sequenced the Trichodesmium growing
in each of the different treatments and compared the genetic expression of the nitrogen
fixation.
In our long-term study, we found an increase in the nitrogen fixation genetic
expression when Trichodesmium was grown under higher concentrations of CO2. We
also saw an inverse effect where the intergenic regions just upstream of the nitrogen
fixation genes were generally down-regulated under higher CO2 and up-regulated at
lower CO2 levels. As the intergenic regions tended to show a coupled effect with their
complemented genic regions, we deduce that these intergenic regions can affect and even
repress the genic regions. This being the case, we can further explore the sequences and
structures of these intergenic regions amongst other nitrogen fixing cyanobacteria and
potentially propose novel non-coding RNAs.

Advisor: David Hutchins
Master´s Degree Project, 60 credits, 2012
Department of Marine Environmental Biology, University of Southern California},
  author       = {Polgar, Randall},
  language     = {eng},
  note         = {Student Paper},
  title        = {Investigation of intergenic influence on some nitrogen fixation nif operons in Trichodesmium erythraeum IMS101},
  year         = {2012},
}