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Dessication Stress., Steven Hand, Michael Menze

Faculty and Staff Scholarship

The threat of desiccation for organisms inhabiting the intertidal zone occurs during emersion at low tides or when organisms are positioned in the high intertidal zone, where wetting occurs primarily by spring tides, storm waves, and spray. Drying due to evaporative water loss is the most common mechanism for dehydration, although during winter in northern temperate regions freezing can also occur, which reduces the liquid water in extracellular fluids and can lead to intracellular dehydration in multicellular organisms. Freezing tolerance has been reported and characterized for a number of intertidal invertebrates, including gastropods such as an air-breathing snail and a …

Drosophila Piwi Associates With Chromatin And Interacts Directly With Hp1a, Brent Brower-Toland, Seth Findley, Ling Jiang, Li Liu, Hang Yin, Monica Dus, Pei Zhou, Sarah C.R. Elgin, Haifan Lin

Biology Faculty Research

The interface between cellular systems involving small noncoding RNAs and epigenetic change remains largely unexplored in metazoans. RNA-induced silencing systems have the potential to target particular regions of the genome for epigenetic change by locating specific sequences and recruiting chromatin modifiers. Noting that several genes encoding RNA silencing components have been implicated in epigenetic regulation in Drosophila, we sought a direct link between the RNA silencing system and heterochromatin components. Here we show that PIWI, an ARGONAUTE/PIWI protein family member that binds to Piwi-interacting RNAs (piRNAs), strongly and specifically interacts with heterochromatin protein 1a (HP1a), a central player in heterochromatic …

Manipulating Underdetermination In Scientific Controversy: The Case Of The Molecular Clock, Michael Dietrich, Robert A. Skipper

Dartmouth Scholarship

Where there are cases of underdetermination in scientific controversies, such as the case of the molecular clock, scientists may direct the course and terms of dispute by playing off the multidimensional framework of theory evaluation. This is because assessment strategies themselves are underdetermined. Within the framework of assessment, there are a variety of trade-offs between different strategies as well as shifting emphases as specific strategies are given more or less weight in assessment situations. When a strategy is underdetermined, scientists can change the dynamics of a controversy by making assessments using different combinations of evaluation strategies and/or weighting whatever strategies …

Survival Of Pacific White Shrimp, , In Low-Salinity And Mixed-Ion Environments, Kirk Parmenter

All Theses

This study was conducted to (1) evaluate the effectiveness of two different salt mixtures, MI-2 (NaCl, MgSO4, MgCl2, KCl, CaCl2, and NaHCO3) and MI (NaCl, MgCl2, KCl, and CaCl2) as compared to artificial sea salt (SS) to provide a sufficient environment for the survival of Litopenaeus vannamei and (2) determine if additions of the MI-2 salt mixture to low concentrations of sea salt would result in comparable survival as that seen in pure SS environments.
Tests conducted at 5 g/L of total dissolved solids showed that the pure SS treatment had a significantly higher survival rate than the MI-2 and …

Mutants And Assay System To Identify Usp/Rxr Ligands, Grace Jones, Davy Jones

Biology Faculty Patents

The invention relates to mutant nuclear hormone receptors that encode mutant nuclear hormone receptors, in which particular amino acid residues are substituted with respect to wild type, so as to be able to detect ligand binding to the mutant receptor by either a change in a physical property of the mutant receptor and/or an transcriptional induction of a nuclear hormone receptor construct. The invention also relates to a nuclear hormone receptor response element denoted by the formula YDRXZ comprising a direct repeat (DR) comprising two half sites separated by X nucleic acid bases; wherein Z indicates the presence of at …

Evidence For Gondwanan Vicariance In An Ancient Clade Of Gecko Lizards, Tony Gamble, Aaron M. Bauer, E. Greenbaum, Todd R. Jackman

Biological Sciences Faculty Research and Publications

Aim

Geckos (Reptilia: Squamata), due to their great age and global distribution, are excellent candidates to test hypotheses of Gondwanan vicariance against post‐Gondwanan dispersal. Our aims are: to generate a phylogeny of the sphaerodactyl geckos and their closest relatives; evaluate previous phylogenetic hypotheses of the sphaerodactyl geckos with regard to the other major gecko lineages; and to use divergence date estimates to inform a biogeographical scenario regarding Gondwanan relationships and assess the roles of vicariance and dispersal in shaping the current distributions of the New World sphaerodactyl geckos and their closest Old World relatives.

Location

Africa, Asia, Europe, South America, …

A Statewide Biomarker Approach To Estimate Contaminant Effects In The Wadeable Streams Of South Carolina, Molly Keaton

All Theses

Freshwater species in South Carolina have been declining for many years. However, the threats that these organisms face from point and non-point source pollution are largely unknown. The South Carolina Department of Natural Resources (SCDNR) began a five year survey of the wadeable streams of South Carolina in May 2006. One of the purposes of this study was to use molecular biomarkers of contaminant exposure to fully assess the health of fish in South Carolina's freshwater streams. During the first year of the study, sunfish (Lepomis sp.) were sampled from May through September 2006 at randomly selected sites in three …

Protective Capactiy Of Mangroves During Tropical Storms: A Case Study From 'Wilma' And 'Gamma' In Belize, Elise F. Granek, Benjamin I. Ruttenberg

Biological Sciences

Globally threatened mangrove forest habitat is often considered an important buffer protecting coastlines from wave and storm impacts and coastal erosion. However, there is little empirical data quantifying the protective effects of mangroves during storms, primarily because of the difficulty of predicting where and when a storm will intersect the shoreline, to facilitate data collection before and after storm events. In 2005, opportunistic results from an ongoing study quantifying differences between intact and cleared mangrove areas on Turneffe Atoll, Belize, provided such pre- and post-storm data from tropical storms ‘Wilma’ (later a Category 5 Hurricane) and ‘Gamma’. We compared differences …

Heritability Of Latent Period Estimated From Wild-Type And Selected Populations Of Puccinia Triticina, Jeffery S. Lehman, Gregory Shaner

Biology and Earth Science Faculty Scholarship

Durability of partially resistant wheat cultivars to wheat leaf rust depends on the amount of genetic variation in parasitic fitness within populations of the pathogen Puccinia triticina. To assess the durability of partial resistance, selection experiments were used to explore quantitative variation in parasitic fitness of P. triticina. Fungal populations 881-WT and 882-WT were selected for shortened latent period on partially resistant cvs. CI 13277 and Sw 72469-6 for multiple generations. Fitness components were measured for wild-type and selected fungal populations. Responses to selection and selection differentials were calculated, and broad-sense, realized heritabilities for latent period were estimated for wild-type …

The Effect Of Dispersal Ability In Winter And Summer Stoneflies On Their Genetic Differentiation, Alison L. Yasick, Robert A. Krebs, Julie A. Wolin

Biological, Geological, and Environmental Faculty Publications

1. Plecopteran species disperse less than most other aquatic insects. Within stoneflies, members of different families vary in the degree of wing morphology and season of adult emergence.

2.  Dispersal limitations were tested to determine if there were increased differences among the nearby, Chagrin and Grand River populations in north-eastern Ohio, by comparing genetic variation within the 16s rRNA region of mitochondrial DNA in two stoneflies. Allocapnia recta emerges in winter and often has rudimentary wings, and Leuctra tenuis emerges in summer with fully developed wings.

3. There was significant genetic variability between the samples of A. recta from two …

Changes In Major Element Hydrochemistry Of The Pecos River In The American Southwest Since 1935, Fasong Yuan, Seiichi Miyamoto, Shilpa Anand

Biological, Geological, and Environmental Faculty Publications

The Pecos River, situated in eastern New Mexico and western Texas, receives water from a drainage area of 91 000 km². There are primarily two major water inputs, namely snowmelt from winter storms in the headwater region of the southern Rocky Mountains and runoff from warm-season monsoonal rainfall in the lower valley. The Pecos River suffers from high levels of total dissolved solids (TDS >5000 mg L⁻¹) under normal flow conditions. This not only poses serious problems for agricultural irrigation and safe drinking water supply, but also results in a permanent loss of biodiversity. This study …

The Relationship Between Disperal Ability And Geographic Range Size, Sarah E. Lester, Benjamin I. Ruttenberg, Steven D. Gaines, Brian P. Kinlan

Biological Sciences

There are a variety of proposed evolutionary and ecological explanations for why some species have more extensive geographical ranges than others. One of the most common explanations is variation in species’ dispersal ability. However, the purported relationship between dispersal distance and range size has been subjected to few theoretical investigations, and empirical tests reach conflicting conclusions. We attempt to reconcile the equivocal results of previous studies by reviewing and synthesizing quantitative dispersal data, examining the relationship between average dispersal ability and range size for different spatial scales, regions and taxonomic groups. We use extensive data from marine taxa whose average …

Recombination And Positive Selection Contribute To Evolution Of Listeria Monocytogenes Inla, R. H. Orsi, D. R. Ripoll, M. Yeung, K. K. Nightingale, M. Wiedmann

Biological Sciences

The surface molecule InlA interacts with E-cadherin to promote invasion of Listeria monocytogenes into selected host cells. DNA sequencing of inlA for 40 L. monocytogenes isolates revealed 107 synonymous and 45 nonsynonymous substitutions. A frameshift mutation in a homopolymeric tract encoding part of the InlA signal peptide was identified in three lineage II isolates, which also showed reduced ability to invade human intestinal epithelial cells. Phylogenies showed clear separation of inlA sequences into lineages I and II. Thirteen inlA recombination events, predominantly involving lineage II strains as recipients (12 events), were detected and a number of amino acid residues were …

Hiv-2 Rna Dimerization Is Regulated By Intramolecular Interactions In Vitro, Tayyba T. Baig, Jean-Marc Lanchy, J. Stephen Lodmell

Biological Sciences Faculty Publications

Genomic RNA dimerization is an essential process in the retroviral replication cycle. In vitro, HIV-2 RNA dimerization is mediated at least in part by direct intermolecular interaction at stem-loop 1 (SL1) within the 5'-untranslated leader region (UTR). RNA dimerization is thought to be regulated via alternate presentation and sequestration of dimerization signals by intramolecular base- pairings. One of the proposed regulatory elements is a palindrome sequence ( pal) located upstream of SL1. To investigate the role of pal in the regulation of HIV-2 dimerization, we randomized this motif and selected in vitro for dimerization- competent and dimerization-impaired RNAs. Energy minimization …

High Rates Of Sulfate Reduction In A Low-Sulfate Hot Spring Microbial Mat Are Driven By A Low Level Of Diversity Of Sulfate-Respiring Microorganisms, Jesse G. Dillon, Susan Fishbain, Scott R. Miller, Brad M. Bebout, Kristen S. Habicht, Samuel M. Webb, David A. Stahl

Biological Sciences Faculty Publications

The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesuffiovibrio-like population. Reduced activity at greater depths was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most …

Phylogeography Of The Thermophilic Cyanobacterium Mastigocladus Laminosus, Scott R. Miller, Richard W. Castenholz, Deana Pedersen

Biological Sciences Faculty Publications

We have taken a phylogeographic approach to investigate the demographic and evolutionary processes that have shaped the geographic patterns of genetic diversity for a sample of isolates of the cosmopolitan thermophillic cyanobacterial Mastigocladus laminosus morphotype collected from throughout most of its range. Although M. laminosus is found in thermal areas throughout the world, our observation that populations are typically genetically differentiated on local geographic scales suggests the existence of dispersal barriers, a conclusion corroborated by evidence for genetic isolation by distance. Genealogies inferred using nitrogen metabolism gene sequence data suggest that a significant amount of the extant global diversity of …

Genetic Determinants Of Reproductive Isolation In Xenopus, John Malone

Biology Dissertations - Archive

Haldane's rule states that in F1 interspecific hybrids the heterogametic sex (XY or ZW) suffers the most dysfunctional effects of hybridization. Frogs of the genus Xenopus have ZW sex determination yet hybrid males are completely sterile and hybrid females are fertile, a pattern exactly opposite of Haldane's rule. One of the most compelling hypotheses to explain this pattern is faster male evolution. The faster male evolution hypothesis suggests that hybrid male sterility is more common than hybrid female sterility because of faster divergence of male reproductive genes (due to sexual selection), or inherent sensitivity with the process of spermatogenesis. This …

Monte Carlo Analysis Of Refuge Site Selection: Statistical Properties And An Empirical Example, Anna Michelle Lawing

Biology Theses - Archive

The Monte Carlo method can be a useful technique providing information on central tendencies and tolerance for selection data. There are many statistical hypothesis tests that are employed in selection studies, but most require the data are normally distributed to adhere to the null hypothesis based on a normal distribution. Monte Carlo methods build a null distribution to test hypotheses based on available conditions and therefore do not require distributions of data to be normal. A Monte Carlo is also an extremely flexible technique and can be designed to test hypotheses for any particular experimental design. I designed a Monte …

Rate Of Diversification In Crickets (Orthoptera: Ensifera) And A Possible Role Of F Supergroup Wolbachia In Bush Crickets, Kanchana Panaram

Biology Dissertations - Archive

Part I: Rates of speciation can tell us more than how many species have survived over a period of time. They indicate whether there are some characteristics of organisms or biogeography scenarios facilitate or hinder speciation. Many groups of ensiferan insects (e.g. Hawaiian sword-tailed, North American ground and field crickets) have been reported to have rapid speciation rates. To investigate whether the pattern of rapid speciation is common in crickets, we estimated overall diversification rates as a whole and within the clade. Ensifera as a whole does not appear to have particularly rapid diversification rates compared to other insect suborders. …

Effects Of Calcium Availability On The Reproductive Output Of Insectivorous Bats, Christina M. Booher

All-Inclusive List of Electronic Theses and Dissertations

Reproduction is a period of high calcium demand in vertebrates, and calcium deficiency can limit reproductive output in mammals. Insects are a poor calcium source, suggesting that insectivorous species are more likely to be calcium deficient. Pregnant big brown bats (Eptesicus fuscus) consume 10 times less calcium than they are estimated to require. To accommodate calcium demand during pregnancy, many mammals mobilize more calcium from the skeleton, and extensive bone loss has been observed in some bats during pregnancy. A conflict may arise between the female and developing embryo over allocation of limited calcium supplies, which could limit reproductive output …

In Vitro Plant Regeneration From Petiole-Derived Callus And Characterization Of Inter Simple Sequence Repeat (Issr) Markers Of Amorphophallus Hewittii Alder W. (Araceae), Douglas Charles Bertelsen

Student Work

The genus Amorphophallus contains many species that are sought after by collectors. A large proportion of these species do not reproduce quickly enough to satisfy the demand. Consequently, the establishment of micropropagation methods to increase the supply is desirable. Though several protocols for tissue culture do exist, these focus on species of agricultural importance that naturally reproduce vegetatively. This research demonstrated the successful in vitro reproduction of Amorphophallus hewittii Alderw., a species that is not known to reproduce vegetatively. The protocol avoided destroying the parent plant through use of petiole material. It concluded with direct transfer of shoots to soil, …

The Effects Of Aging And Activity On Glial Cell Line-Derived Neurotrophic Factor Expression In Skeletal Muscle, Nathan Peplinski

Dissertations

Glial cell line-derived neurotrophic factor (GDNF) is an extracellular signaling protein that is produced by skeletal muscle and is important for the motor neurons that control muscle movement. GDNF has been shown to keep neurons alive under conditions that they would otherwise not persist. In skeletal muscle, GDNF has been shown to be one of the most potent neurotrophic factors that influence motor neuron survival. While the role of GDNF has been well studied during early development, not much is known about what happens to GDNF expression in the adult and with advanced aging. Previous results from our lab have …

Venom Expenditure By Viperid And Elapid Snakes: Mechanisms, Adaptation, And Application, Shelton Scott Herbert

Loma Linda University Electronic Theses, Dissertations & Projects

In this dissertation, I examined some of the factors that influence venom expenditure by viperid and elapid snakes in both predatory and defensive contexts. I also considered the consequences of venom delivery into human snakebite victims. In the first of four experiments, In the first experiment, I explored whether the Black-necked Spitting Cobra (Naja nigricollis) metered venom by differential venom gland contraction. Differences in duration of venom flow and venom expended confirmed that this species ejects markedly greater quantities of venom during biting than spitting by varying the duration of venom gland contraction. In the second experiment, I studied the …

Human Body Temperature (37°C) Increases The Expression Of Iron, Carbohydrate, And Amino Acid Utilization Genes In Escherichia Coli K-12, Christine A. White-Ziegler, Amy J. Malhowski, Sarah Young

Biological Sciences: Faculty Publications

Using DNA microarrays, we identified 126 genes in Escherichia coli K-12 whose expression is increased at human body temperature (37°C) compared to growth at 23°C. Genes involved in the uptake and utilization of amino acids, carbohydrates, and iron dominated the list, supporting a model in which temperature serves as a host cue to increase expression of bacterial genes needed for growth. Using quantitative real-time PCR, we investigated the thermoregulatory response for representative genes in each of these three categories (hisJ, cysP, srlE, garP, fes, and cirA), along with the fimbrial gene papB. Increased expression at 37°C compared to 23°C was …