Biology Commons^™

Structures Of Human Thymidylate Synthase R163k With Dump, Fdump And Glutathione Show Asymmetric Ligand Binding, Lydia M. Gibson, Lesa R. Celeste, Leslie L. Lovelace, Lukasz Lebioda

Faculty Publications

Thymidylate synthase (TS) is a well validated target in cancer chemotherapy. Here, a new crystal form of the R163K variant of human TS (hTS) with five subunits per asymmetric part of the unit cell, all with loop 181-197 in the active conformation, is reported. This form allows binding studies by soaking crystals in artificial mother liquors containing ligands that bind in the active site. Using this approach, crystal structures of hTS complexes with FdUMP and dUMP were obtained, indicating that this form should facilitate high-throughput analysis of hTS complexes with drug candidates. Crystal soaking experiments using oxidized glutathione revealed that …

The Mathematics Of Animal Behavior: An Interdisciplinary Dialogue, Shandelle M. Henson, James L. Hayward

Faculty Publications

No abstract provided.

Repression Of Wnt Signaling By A Fer-Type Nonreceptor Tyrosine Kinase, Aaron P. Putzke, Joel H. Rothman

Faculty Publications

The Wnt signaling pathway must be properly modulated to ensure an appropriate output: pathological conditions result from either insufficient or excessive levels of Wnt signal. For example, hyperactivation of the Wnt pathway is associated with various cancers and subnormal Wnt signaling can lead to increased invasiveness of tumor cells. We found that the Caenorhabditis elegans ortholog of the Fer nonreceptor tyrosine kinase, FRK-1, limits Wnt signaling by preventing the adhesion complex-associated beta-catenin, HMP-2, from participating in Wnt-dependent specification of the endoderm during embryogenesis. Removal of FRK-1 function results in relocalization of HMP-2 to the nucleus of epidermal cells, and allows …

Glutamine Synthetase Partitioning In Native And Introduced Salt Marsh Grasses, Eric L.G. Hazelton, Thomas J. Knight Phd, Theresa A. Theodose Phd

Faculty Publications

Plants with higher glutamine synthetase (GS) activity in photosynthetic tissues than below-ground structures (high leaf:root [L:R] GS activity) show growth advantages over plants with a low L:R GS activity ratio. The benefits of a high L:R GS activity ratio are well documented in agricultural systems, but little is known about the ecology of GS partitioning in natural systems. To determine the ecological significance of GS partitioning, we measured above- and below-ground GS activity in Spartina grasses field-collected from a Maine salt marsh and others raised in a growth chamber from seed. The more stress-tolerant, faster growing S. alterniflora had a …

Weeds In The Flower Garden: An Exploration Of Plagiarism In Graduate Students’ Research Proposals And Its Connection To Enculturation, Esl, And Contextual Factors, Joanna Gilmore, Denise Strickland, Briana Eileen Timmerman, Michelle Maher, David Feldon

Faculty Publications

Existing literature provides insight into the nature and extent of plagiarism amongst undergraduate students (e.g., Ellery, 2008; Parameswaran & Devi, 2006; Selwyn, 2008). Plagiarism amongst graduate students is relatively unstudied, however, and the existing data are largely based on self-reports. This study investigated the rates and potential causes of plagiarism amongst graduate students in master’s and doctoral programmes in science, technology, engineering, mathematics, and science or mathematics education by examining actual research proposals written by graduate students. Results indicate that plagiarism is a prevalent issue at each of the three university sites sampled and across all of the investigated disciplines. …

Chemical Inhibition Of Caax Protease Activity Disrupts Yeast Ras Localization, Surya P. Mandahar, Emily R. Hildebrandt, William H. Jacobsen, George M. Santangelo, Walter K. Schmidt

Faculty Publications

Proteins possessing a C-terminal CaaX motif, such as the Ras GTPases, undergo extensive post-translational modification that includes attachment of an isoprenoid lipid, proteolytic processing and carboxylmethylation. Inhibition of the enzymes involved in these processes is considered a cancer-therapeutic strategy. We previously identified nine in vitro inhibitors of the yeast CaaX protease Rce1p in a chemical library screen (Manandhar et al., 2007). Here, we demonstrate that these agents disrupt the normal plasma membrane distribution of yeast GFP-Ras reporters in a manner that pharmacologically phenocopies effects observed upon genetic loss of CaaX protease function. Consistent with Rce1p being the in vivo target …

Genomic Organization And Molecular Phylogenies Of The Beta (Β) Keratin Multigene Family In The Chicken (Gallus Gallus) And Zebra Finch (Taeniopygia Guttata): Implications For Feather Evolution, Matthew J. Greenwold, Roger H. Sawyer

Faculty Publications

Background: The epidermal appendages of reptiles and birds are constructed of beta (β) keratins. The molecularphylogeny of these keratins is important to understanding the evolutionary origin of these appendages, especially feathers. Knowing that the crocodilian β-keratin genes are closely related to those of birds, the published genomes ofthe chicken and zebra finch provide an opportunity not only to compare the genomic organization of their β- keratins,but to study their molecular evolution in archosaurians.

Results: The subfamilies (claw, feather, feather-like, and scale) of β-keratin genes are clustered in the same 5' to 3' orderon microchromosome 25 in chicken and zebra finch, …

Development Of A ‘Universal’ Rubric For Assessing Undergraduates’ Scientific Reasoning Skills Using Scientific Writing, Briana Eileen Timmerman, Denise Strickland, Robert L. Johnson, John R. Payne

Faculty Publications

We developed a rubric for measuring students’ ability to reason and write scientifically. The Rubric for Science Writing (Rubric) was tested in a variety of undergraduate biology laboratory courses (total n = 142 laboratory reports) using science graduate students (teaching assistants) as raters. Generalisability analysis indicates that the Rubric provides a reliable measure of students’ abilities (g = 0.85) in these conditions. Comparison of student performance in various biology classes indicated that some scientific skills are more challenging for students to develop than others and identified a number of previously unappreciated gaps in the curriculum. Our findings suggest that use …

Role Of Casein Kinase 1 In The Glucose Sensor-Mediated Signaling Pathway In Yeast, Satish Pasula, Samujjwal Chakraborty, Jae H. Choi, Jeong-Ho Kim

Faculty Publications

Background

In yeast, glucose-dependent degradation of the Mth1 protein, a corepressor of the glucose transporter gene (HXT) repressor Rgt1, is a crucial event enabling expression of several HXT. This event occurs through a signaling pathway that involves the Rgt2 and Snf3 glucose sensors and yeast casein kinase 1 and 2 (Yck1/2). In this study, we examined whether the glucose sensors directly couple with Yck1/2 to convert glucose binding into an intracellular signal that leads to the degradation of Mth1.

Results

High levels of glucose induce degradation of Mth1 through the Rgt2/Snf3 glucose signaling pathway. Fluorescence microscopy analysis …

The Role Of Adaptive Trans-Generational Plasticity In Biological Invasions Of Plants, Andrew R. Dyer, Cynthia S. Brown, Erin K. Espeland, John K. Mckay, Harald Meimberg, Kevin J. Rice

Faculty Publications

High-impact biological invasions often involve establishment and spread in disturbed, high-resource patches followed by establishment and spread in biotically or abiotically stressful areas. Evolutionary change may be required for the second phase of invasion (establishment and spread in stressful areas) to occur. When species have low genetic diversity and short selection history, within-generation phenotypic plasticity is often cited as the mechanism through which spread across multiple habitat types can occur. We show that trans-generational plasticity (TGP) can result in pre-adapted progeny that exhibit traits associated with increased fitness both in high-resource patches and in stressful conditions. In the invasive sedge, …

Organismal Climatology: Analyzing Environmental Variability At Scales Relevant To Physiological Stress, Brian Helmuth, Bernardo R. Broitman, Lauren Yamane, Sarah E. Gilman, Katharine Mach, K. A.S. Mislan, Mark W. Denny

Faculty Publications

Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species’ range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different …

Latitudinal Differences In The Hibernation Characteristics Of Woodchucks (Marmota Monax), Stam M. Zervanos, Christine R. Maher Phd, Jerry A. Waldvogel, Gregory L. Florant

Faculty Publications

There is little information on the phenotypic flexibility of hibernation characteristics within species. To address this issue, we observed differences in hibernation characteristics of three free-ranging populations of woodchucks (Marmota monax) distributed along a latitudinal gradient from Maine to South Carolina. Data from free-ranging animals exhibited a direct relationship between latitude and length of the hibernation season. As expected, woodchucks in the northern latitudes hibernated longer than those in the southern latitudes. Also, the length of interbout arousals decreased with increase in latitude, whereas the length of torpor bouts and the number of arousals increased. Thus, we observed phenotypic plasticity …

Occurrence Of Anisophylly And Anisoclady Within The Amaranthaceae [Abstract], Donald B. Pratt, Lynn G. Clark

Faculty Publications

No abstract provided.

Batrachochytrium Dendrobatidis Detected In Amphibians From National Forests In Eastern Texas, Usa, Daniel Saenz, Brendan T. Kavanagh, Matthew Kwiatkowski

Faculty Publications

The amphibian disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd, Longcore et al. 1999), is well known as a major threat to amphibians resulting in mass die-offs and population declines throughout the world (Berger et al. 1998; Blaustein and Keisecker 2002; Daszak et al. 2003; McCallum 2005; Rachowicz et al. 2006). Batrachochytrium dendrobatidis has been detected on amphibians from sites across North America (Ouellet et al. 2005; Woodhams et al. 2008) and appears to be most prevalent in the western and the northeastern United States (Longcore et al. 2007; Schlaepfer et al. 2007). Whereas infected anurans also have …

Development And Characterization Of 16 Microsatellite Markers For The Louisiana Pine Snake, Pituophis Ruthveni, And Two Congeners Of Conservation Concern, Matthew Kwiatkowski, Christopher M. Somers, Ray G. Poulin, D. Craig Rudolph, Jessica Martino, Tracey D. Tuberville, Cris Hagen, Stacey L. Lance

Faculty Publications

We isolated and characterized 16 microsatellite loci from the Louisiana pine snake, Pituophis ruthveni. Loci were screened in 24 individuals from locations throughout its distribution in Louisiana and Texas. The number of alleles per locus ranged from 4 to 12, observed heterozygosity ranged from 0.200 to 0.875, and the probability of identity ranged from 0.043 to 0.298. We examined cross-species amplification at these loci in P. catenifer (bullsnakes and gopher snakes) and P. melanoleucus (pine snakes). These new markers provide tools for examining the conservation genetics of this species complex. Louisiana pine snakes face numerous threats: population densities are extremely …

Methane Emission From A Tropical Wetland In Ka'au Crater, O'Ahu, Hawai'i, Maxime Grand, Eric Gaidos

Faculty Publications

Natural tropical wetlands constitute an important but still poorly studied source of atmospheric methane, a powerful greenhouse gas. We measured net methane emission, soil profiles of methane generation and oxidation, and related environmental parameters in a tropical wetland occupying the Ka'au extinct volcanic crater on the Hawaiian island of O'ahu. The wetland has a fluctuating water table with dynamics that can be reproduced using precipitation data and a simple model. Median net methane flux was 117 mg m-2 day-1 and is consistent with measurements at other tropical sites. Net methane flux in the Commelina diffusa—dominated vegetation pattern (honohono) was significantly …

Evolution Of An Mhc Class La Gene Fragment In Four North American Morone Species, J. X. Liu, Bert Ely

Faculty Publications

A nucleotide sequence analysis of a fragment of a Morone MHC class Ia gene detected high levels of polymorphism in striped bass Morone saxatilis, white perch Morone americana and yellow bass Morone mississippiensis. Extremely low levels of MHC diversity, however, were detected in white bass Morone chrysops, suggesting the possibility of a severe population bottleneck for this species.

Xenopus Development From Late Gastrulation To Feeding Tadpole In Simulated Microgravity, Wendy M. Olson, Darrell Wiens, Theresa L. Gaul, Manuela Rodriguez, Cherie L. Hauptmeier

Faculty Publications

Microgravity (microG) is known to influence cytoskeletal structure, but its effects on cell migration are not well understood. To examine the effects of altered gravity on neural crest cell (NCC) migration, we inserted Xenopus laevis embryos into two separate microG-simulating slow turning lateral vessels (STLVs) just before neurulation (stage 11-12), and exposed them until feeding stage (stage 45), when the jaws and branchial apparatus are fully functional. To evaluate apparatus-related artifacts, we used two different STLVs and a vibration control as well as a stationary control vessel. Larval growth, pattern of NCC-derived cartilage formation, and incidence of malformations were analyzed …

Distribution Of Tadpoles Of Ollotis Occidentalis (Amphibia: Anura: Bufonidae) Along The Rio Salado, Puebla, Mexico, G. A. Woolrich-Pina, Geoffrey R. Smith, L. Oliver-Lopez, M. Barbosa Morales, J. A. Lemos-Espinal

Faculty Publications

No abstract provided.

Evaluation Of The Rate Of Artificial Coverboard Use By The Salamander, Plethodon Cinereus, In The Vicinity Of Natural Cover Objects, K. Ciul, L. Simpson, Geoffrey R. Smith, Jessica E. Rettig

Faculty Publications

No abstract provided.

Substrate And Cover Object Choice By The Red-Backed Salamander (Plethodon Cinereus), J. P. Iverson, Geoffrey R. Smith

Faculty Publications

No abstract provided.