Peter Davies, PhD - US grants

Light causes a pronounced decrease in stem growth rate. Dr. Davies proposes to investigate the kinetics of hormonal changes in relation to the growth kinetics following the transition from dark to red light in order to determine to what extent, and in what manner, changes in endogenous hormones may mediate light- induced changes in stem growth rate. Red light will be used to reduce the complexity inherent in white light. Dr. Davies will use a range of pea length genotypes whose gibberellin (GA) content is known. All of the genotypes grow faster in the dark than in the light but vary in the proportional reduction in their growth rate in the light. In some genotypes GAs are absent yet they are tall; in such plants he finds a very high indoleacetic acid (IAA) level. He has considerable evidence that GA may act via the induction of tryptophan racemase causing the production of D-tryptophan, which is then the precursor of IAA. The kinetics of growth are recorded by position transducers under darkness and illumination of known spectral composition, and following hormone and inhibitor applications. GAs, IAA and IAA conjugates, will be measured by gas chromatography-mass spectrometry and components of the IAA synthesis pathway assayed. This will show the point(s) in the GA and IAA metabolic pathways at which light acts, and whether a light induced change in GA levels in fact operates by altering the level of IAA. %%% Light causes a decrease in the growth of stems of plants previously grown in the dark. The mechanism by which this occurs is unknown. One possibility is that light alters the level of plant hormones. To determine whether plant hormones are involved one need to know the rate at which light induces a decrease in growth, and then examine the changes in the internal levels of the plant hormones to see if they change at the same time. Dr. Davies will measure the rate of growth change and hormonal content in pea varieties which have different stem lengths. The difference in stem lengths is genetically controlled, and has been shown to be due to changes in levels or responsiveness to plant hormones called gibberellins. There is also evidence that this hormone may interact in some way in the synthesis of another hormone, indoleacetic acid. Dr. Davies will measure the changes in the internal levels of gibberellin and indole acetic acid to determine if and how light causes a decrease in stem growth. This will improve our knowledge of how plants grow.

Four plant growth chambers will be acquired to promote research in the areas of plant physiology, plant molecular biology, and plant biophysics. Specific projects will investigate: 1) developmental physiology in plants; 2) photosynthate partitioning and transmembrane transport; 3) molecular genetics of chloroplast coupling factor; 4) transfer cells and phloem loading; and 5) biophysical aspects of photosynthesis.

This application requests partial support for the 1990 FASEB Summer Research Conference on Retinoids. This conference is scheduled to be held June 17-22, 1990 at the Vermont Academy in Saxton's River, VT. The field of retinoid research has expanded in the last decade to include scientists from diverse areas. The major goal of this conference is to provide a common forum to scientists from different countries and backgrounds to learn about the latest developments in retinoid research and share their ideas with colleagues. This is particularly important for junior researchers who are finding productive and stimulating environments for their future endeavors. The conference will provide a poster discussion session to maximize active participation by junior researchers. Research on retinoids is important for understanding cell communication, development and differentiation, phototransduction in vision, and regulation of gene expression. This conference will provide the opportunity for researchers working in these diverse areas to discuss their common concerns and develop new approaches that will increase basic knowledge of the function of these important biological molecules.

DESCRIPTION(Adapted from applicant's abstract): The guiding hypothesis of this work is that alterations in the conformation of the microtubule associated protein tau are an important part of a cascade of events that leads to cell death in Alzheimer's disease and certain other neurodegenerative diseases. Genetic studies of families with frontotemporal dementia with Parkinson's disease (FTDP) provide support for this hypothesis. In the next project period, further testing will be carried out by experimental work ranging from in vitro manipulation of tau protein conformation and phosphorylation, cell culture experiments with transfection of various tau constructs and examination of transgenic animals. Five specific aims are proposed: Aim #1. Two short amino acid sequences in tau have been identified as critical for formation of an abnormal conformation of tau, that is similar to that of tau present in the AD brain. Using recombinant tau constructs, structural requirements for generation of this conformation will be further explored. The effects of several point mutations and phosphorylation will also be examined. In Aim #2, the activity of these abnormal tau proteins will be investigated using assays of microtubule binding and promotion of tubulin assembly, to test the hypothesis that the abnormal tau is no longer a functional microtubule binding protein. In Aim #3, selected tau constructs will be transiently transfected into cultured cells to test the hypothesis that specific constructs are non-functional in a cellular environment. In Aim #4, a variety of mice into which normal and mutant human tau transgenes have been introduced will be examined, including unique lines which we will produce. Since the tau mutatons discovered in FTDP are dominant, the hypothesis that these mice will show neuronal degeneration seems reasonable. Aim #5. Using selected antibodies from a large panel of monoclonals to conformational and phosphoepitopes of tau, studies of human brain will continue to attempt to examine the relationship between certain phosphorylations and conformational changes in tau, especially focusing on early AD cases.

In recent years the field of ethylene biology has been strongly and positively impacted by genomics approaches and represents an area with many opportunities to translate genomics into practical real-world products and solutions. The 8th International Symposium on the Plant Hormone Ethylene to be held June 21 - 25, 2009 at Cornell University in Ithaca, NY will provide a forum for discussion and collaboration for the highly interactive and competitive ethylene community and is anticipated to draw a diverse group of participants that include plant scientists from the public and private sector and breeders from around the world. Topics include but are not limited to 1) hormone synthesis and signal transduction, 2) biotic and abiotic stress responses, 3) ripening and senescence, and 4) postharvest physiology and applied ethylene biology. The participation of graduate students, postdoctoral and beginning investigators will be fostered through travel awards to attend the Symposium. Funding provided by NSF will be used to broaden participation of young scientists and those from underrepresented groups from the US scientific community. Symposium program and abstracts will be publicly available online at the symposium website (http://www.hort.cornell.edu/ethylene/) and through a program book of abstracts that will be distributed to meeting attendees.