Spring 2015 Asa Gray Seminars
March 2nd, 2015, 4 pm in Donahue Auditorium
Jay W. Wason
Doctoral Candidate at SUNY College of Environmental Science and Forestry, Syracuse, NY
Title:
The Deliberation of the Ents: Tree Community Response Lags Recent Environmental Change in Northeastern Mountain forests.
Abstract: Recent environmental changes are expected to alter vegetation distributions and productivity, yet it is still unclear how and when these changes will take place in forested ecosystems. Due to their long life-spans the effects of climate change on tree species may lag behind optimal tracking of ideal climate-space. To address these questions we studied changes in range limits, abundance, and growth rates of spruce-fir forest tree species. We used historic mountain vegetation plots from the 1960s and 1980s on Whiteface Mountain, New York, and combined them with a new region wide vegetation survey from 11 additional mountains in New York, Vermont, New Hampshire, and Maine. We found that recent environmental change has altered growth-climate relations of red spruce (Picea rubens) and balsam fir (Abies balsamea) trees along the elevational gradient. However, we did not find clear evidence of a synchronous spruce-fir tree community range shift upslope. Instead, species specific distribution changes, while linked to climate, were often a result of stand level disturbance dynamics. We conclude that while growth is already responding to recent environmental change, impacts on distributions and demographics of forest tree species may be lagged due to their long-lived nature.
March 23rd, 2015, 4 pm in Donahue Auditorium
Jeffrey Amack, Ph.D.
,Associate Professor of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
Title:
Cilia and the Asymmetric Vertebrate Body Plan.
Abstract: In contrast to the external bilateral symmetry of the vertebrate body plan, the cardiovascular system and gastrointestinal tract develop asymmetries along the left-right (LR) body axis. Defects in establishing LR asymmetry during embryonic development are known to cause a broad spectrum of congenital malformations, but the genes and mechanisms involved in this process are only poorly understood. In humans and model vertebrates, conserved motile cilia play an important role in LR development. These cilia generate an asymmetric fluid flow in a transient epithelial ?organ of asymmetry? to initiate a signaling cascade that ultimately guides asymmetric morphogenesis of the heart and gut. We are using zebrafish as a model vertebrate to understand how cilia generate LR signals. A unique combination of high-resolution live imaging, fluorescent transgenic reporter lines and targeted gene modulation strategies has been developed to analyze cilia in the zebrafish organ of asymmetry, called Kupffer?s vesicle (KV). Our goal is to characterize genes and mechanisms that control LR development in zebrafish and then apply these insights to understand human birth defects.
March 30, 2015, 4 pm in Donahue Auditorium
Brian Panama, Ph.D.,
Research Scientist of Experimental Cardiology, Masonic Medical Research Laboratory, Utica, NY
Title:
Role of the IRX5 Transcription Factor Gene in Sudden Cardiac Death.
Abstract: Sudden cardiac death (SCD) caused by arrhythmia accounts for more than 300,000 deaths annually in the United States. Ion channels underlie cardiac electrical events and SCD has been linked to mutations in multiple ion channel genes, leading to a loss of function in cardiac sodium and calcium channel activity as well as increased activity of the transient outward potassium current (Ito). The transcription factor Iroquois homeobox-gene-5 (IRX5) is a particular attractive candidate for inherited SCD syndromes due to its transcriptional regulation of Ito.
April 6th, 2015, 4 pm in Donahue Auditorium
Joshua J. Schwartz, Ph.D.,
Professor of Biology, Pace University, Pleasantville, NY
Title:
Nifty Shades of Gray: Communication and Mate Choice in the Treefrog Hyla versicolor.
Abstract: In my talk I will discuss male advertisement and female choice in the dynamic sound environment of choruses of the gray treefrog, Hyla versicolor with particular focus on the problem of communication in noise. As in many species of frogs, males of this species often advertise for mates in dense assemblages characterized by high levels of noise and acoustic clutter. If a male is to be reproductively successful, he must effectively communicate those attributes of his signals or signaling behavior that are relevant to decision making by females in a less than ideal acoustic milieu. Moreover, he must also be aware of the calling behavior of his neighbors so that he can respond to changes in their vocal performance to maintain his relative attractiveness in a very competitive situation. For example, females find longer calls more attractive and male gray treefrogs lengthen their calls in response to the calls of others as well as increasing levels of chorus-generated noise. In pairwise interactions, males alternate vocalizations and so reduce call overlap to levels below that expected by chance. However, in choruses consisting of more males, acoustic interference increases dramatically and males do not seem to exhibit selective attention in a way that reduces call interference among nearest neighbors - although females discriminate strongly against overlapped calls. Moreover, changes made in call duration and rate that occur with increasing noise levels do not aid in signal detection by females and auditory induction, by which the auditory system might perceptually restore masked or missing elements of pulsatile calls, does not occur. Although, under some circumstances, differences in call frequency may help females distinguish among neighboring males, naturalistic spectral differences do not seem to help females perceptually separate the overlapping calls of such males. There is evidence, however, that spatial separation of males can contribute to signal segregation by listening females during acoustic interference.
April 20th, 2015, 4 pm in Donahue Auditorium
Stephen DeVito,
Doctoral Candidate in the Tumor Biology Training Program at Georgetown University Medical Center, Washington, DC
Title:
Novel Relationships Between BER Glycosylases and Mutagenic DNA Adducts
.Abstract: Single nucleotide polymorphisms (SNPs) in base excision repair (BER) enzymes (glycosylases) can lead to faulty repair of DNA adducts. These adducts can cause DNA and RNA polymerases to stall, or cause single and double strand breaks. In addition, if these lesions are not repaired properly, they may have mutagenic consequences for the cell. Glycosylases have target adducts that they are responsible for fixing, e.g., 3-methyladenine glycosylase (MPG) with hypoxanthine (Hx), and 8-oxoguanine (OGG1) with 8-oxoG. However, there is also a degree of back-up activity associated with glycosylases. The extent to which they back one another however, is not well characterized. Here we examine the back-up activity of 3-methyladenine DNA glycosylase (MPG) with Hx. Pervious work has shown that MPG is the only enzyme capable of excising Hx from the DNA base stack. However, we have found though glycosylase activity assays, that Hx is also repaired by OGG1. OGG1 is a bifunctional glycosylase that is shown only to excise oxidative adducts, and not deamination products like Hx . We hypothesize that repair of Hx is initiated by both MPG and OGG1 in cells, which inhibits Hx-induced mutagenesis.