Fall 2009 Asa Gray Seminars
September 28, 2009
Lake Sediment and Biological Response to both Intrabasinal and Extrabasinal Changes over the Past 350 Years, Fulton Chain of Lakes, South-Central Adirondack Mountains
Associate Professor and Chair, Department of Geology, Utica College
Many lakes in the Adirondacks have been impacted by nutrient influx associated with land development and recreation. Studies from other regions have shown that lakes are affected also by changes in climate. Global temperature has increased since the end of the Little Ice Age (mid-to-late 1800s) due to both natural and human factors, and instrumental data suggests the Adirondack region has experienced similar warming as well as a decline in precipitation over the past century. Sediments from Fourth Lake near Old Forge, New York were examined to ascertain if and how the lake has been impacted by climate change. Changes in organic carbon, abundance of total diatoms, and relative abundance of individual diatom taxa in Fourth Lake are observed that correlate with large-scale conditions outside of the lake basin such as northern hemisphere temperature, atmospheric carbon dioxide, and solar irradiance. Such relationships have implications for watershed and lake management as policies intended to lessen the effects of human-induced nutrient loading may need to be made increasingly stringent to compensate for ongoing upward trends in these variables.
October 5, 2009
Discovery of New Bacterial Species from Clinical Specimens
Division of Infectious Disease, New York State Department of Health, Wadsworth Center
Every month some 50 new species of bacteria are discovered. Most are from an environmental source such as air, soil, and even permafrost; only about 3% are from patients. In our role as a reference laboratory, the Bacteriology Laboratory at the Wadsworth Center receives hundreds of bacterial cultures each month, isolated from patients that hospitals and clinics are unable to identify. Using classical culture methodology and molecular DNA sequencing we are able to identify most of these bacteria. None-the-less and despite our best efforts, about 5% remain unidentified. It is within this group we have begun the hunt for new species.
October 19, 2009
Army ants - Studies in Molecular Ecology and Evolution
Junior Fellow at Harvard Society of Fellows, Harvard University, Museum of Comparative Zoology Labs
Army ants are dominant social hunters of invertebrates and thereby play an integral role in tropical ecosystems. They are defined by a suite of evolutionarily interrelated physiological, behavioural and morphological traits, the army ant adaptive syndrome: they are obligate group predators, they frequently relocate their nests, and their permanently wingless queens found new colonies accompanied by workers. Furthermore, army ants typically have extremely male-biased numerical sex-ratios, and queens are inseminated by many males. In this talk I will discuss recent advances in understanding the evolutionary causes and consequences of this unusual life-history.
October 26, 2009
Variation within a summer season in bacteria resistant to antibiotics in the upper Susquehanna River
Chair and Associate Professor of Biology, Department of Biology, Hartwick College
Increasingly bacteria are acquiring resistance to antibiotics, making these compounds ineffective for treatment of disease. Antibiotics enter natural environments from agricultural and municipal water sources. Some bacteria in soils have also been shown to consume antibiotics and use them for growth. These bacteria could help us to clean-up environments polluted with antibiotics, or serve as mechanisms for antibiotic-resistance to spread to bacteria that cause diseases in humans. In either case, knowledge of these microbes in natural settings is important. This presentation will describe efforts to investigate the incidence of antibiotic-resistant bacteria in the upper Susquehanna River over the course of a summer season. Two groups of bacteria were investigated: microbes that commonly inhabit the human intestine and serve as indicators of pollution and naturally occurring microbes that use antibiotics for growth.
November 9, 2009
The Evolution of Bird Eggs and Songs
Postdoctoral Research Fellow, Department of Biology, Morrill Science Center, University of Massachusetts
Birds are valuable study organisms for understanding the evolution of complex traits, especially those that involve learning. They have relatively short generation times for a vertebrate, and are easily studied both in the wild and (for some species) in the laboratory. I describe two studies that show how complex traits that involve learning can evolve by natural selection. First, the village weaverbird (Ploceus cucullatus) has distinctive eggs in Africa, in order to tell when a parasitic cuckoo lays eggs in its nest. After the weaver was introduced to islands without cuckoos, however, they lost some of the distinctiveness of their eggs, and became less able to discriminate against foreign eggs. In the other case study, male swamp sparrows (Melospiza georgiana) sing songs of repeated notes (trills). Faster songs are harder to sing, and females like them better. These birds learn their songs during a narrow time window as juveniles. We brought nestlings into the laboratory and trained them on songs that we experimentally slowed relative to their natural (wild-recorded) rate, in order to see how well birds would learn these lower performance training models. Swamp sparrows memorized the training models regardless of their speed, but they demonstrate two kinds of unlearned and adaptive biases during development: they speed up slower songs, and they reproduce faster songs more accurately. Both of these studies show how inheritance and learning interact to produce the final form of a behavior.
November 16, 2009
“Deceptive Imprinting”-the next major decade in Systems Immunobiology
Peter L. Nara, M.Sc., DVM, Ph.D.
W. Eugene Lloyd Endowed Chair, Director for the Center of Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Department of Biomedical Sciences, College of Veterinary Medicine, and President and CEO, Biological Mimetics, Inc.
The list of disease-causing microbial pathogens is significantly longer than the list of microbes currently controlled or eliminated by vaccine development. It appears that current research and development directed at antigen delivery, vectors, presentation, expression systems and cytokine steering approaches although important, have not fully addressed the problem. As such, it stands that selected genetic instability of the pathogen leading to antigenic variation, coupled with non-protective immunodominance stands as one of the major obstacles in vaccine design today. The immune defense system of the host operates by surveying the “antigenic space” through shapes and linear sequences of chemical information. It appears that microbial pathogens have continued the evolution of selecting for and presenting chemical shapes and sequences on their surfaces (epitopes), which are more immunogenic relative to other biochemically conserved structures on the microbes and structurally dissociated in such a way as to tolerate significant sequence modifications (immunodominant non-protective epitopes-IDNPs). These IDNPs may be deeper in our B and T cell repertoire and act to decoy, misdirect and dysregulate the host’s immune system (Deceptive Imprinting). The technology of Immune Dampening/Refocusing maps, identifies and through site-directed mutagenesis techniques selectively immune dampens the IDNP T and B cell epitopes. New vaccines and therapeutic monoclonal antibodies made by this technology are purposely lacking IDNPs which when used as immunogens induce a new type of antibody with different specificity which convey new immunological and biological properties often conveying broader cross-strain neutralizing antibodies and cell-mediated immune responses and protection.