-
Seminar Detail
Eukaryotes at pH Extremes
Presenter: Linda Amaral Zettler ()
August 25, 2003 12:00 AM Pacific
One of the goals of the Astrobiology Roadmap is to explore the limits of
life on Earth as analogs for environments on Mars, Europa and other planets
that might support life. Earth harbors many extreme environments. Our
preconceived notions concerning the range of habitability for life have
biased many investigations of microbial diversity in these environments. We
have been exploring the genetic and physiological diversity of organisms
living at both acidic (pH < 3) and alkaline (pH >10) pH extremes. I will
present an overview of some of these environments that range from the warm
(45°C), acidic (pH 2.7) Nymph Creek in Yellowstone National Park to
temperate alkaline lakes in the Sandhills region of western Nebraska. The
focus of my presentation, however, will be the acidic, heavy metal rich Rio
Tinto in Southwestern Spain.
Spains Rio Tinto, or Red River, is an example of an extremely acidic (pH
1.7-2.5), high metal environment teeming with prokaryotic and eukaryotic
microbial life. Our recent small-subunit rRNA gene-based studies reveal an
unexpectedly high eukaryotic phylogenetic diversity in the river compared to
the relatively low prokaryotic diversity. We have found that protists in
the river can thrive in and often dominate this environment. I will review
our progress to date on these studies and also provide a glimpse of future
work planned.
Since we have discovered protistan acidophiles closely related to
neutrophiles, we hypothesize that the transition from neutral to acidic
environments occurs rapidly over geological time scales. These studies
identify organisms that live under acid/high metal extremes but tell us
little about how these organisms have adapted to such environments. We are
currently trying to understand how these organisms have adapted to such
environments by exploring the alterations in physiological mechanisms that
might allow for growth of eukaryotic microbes at acid extremes. To this end,
we are isolating phylogenetically diverse protists in order to characterize
and compare ion-transporting ATPases from cultured acidophiles with those
from neutrophilic counterparts. We predict that special properties of these
ion transporters allow protists to survive in the Rio Tinto and other
extreme environments.Participation Instructions
http://nai.arc.nasa.gov/seminars/instructions.cfm
December 21, 2007
Team Overview Seminars: Each of the NAI teams will be giving one hour overview seminars that describe the work they will be performing as members of the NAI. These seminars, which will be broadcast via videoconference and web, will provide an opportunity to find out more about the science, EPO and other activities being performed by the NAI teams.
The Director’s Seminar series features talks from scientists who are invited by the NAI Director to present their research results to the community. A primary goal of the seminars is to encourage interdisciplinary collaboration across NAI teams and within the astrobiology community at large. These seminars are open to all, including the general public; however, the target audience is researchers and students who are engaged in astrobiology. While the seminars are technical in nature, speakers are encouraged to develop presentations that can be understood by colleagues from a variety of disciplines across the field. The talks are typically 50 minutes long, with time at the end for questions and discussion.
The Forum for Astrobiology Research (FAR) seminar provides an opportunity for graduate students to present their research results, and to meet as a student community for mutual encouragement and support. FAR science presentations are typically 20-30 minutes each, with several students presenting during one virtual event. On occasion, the FAR seminar will be devoted to group discussion and planning activities.
The University of Washington seminar series is hosted by the NAI VPL team from their campus in Seattle. NAI provides technical support for the seminar series and produces podcasts of the presentations. The talks are typically 50 minutes long, with time at the end for questions and discussion.
Other virtual seminars, such as workshops and summer student presentations, are hosted by NAI. These are typically scheduled as needed and vary in length, content, and target audience.
