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2001

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Articles 91 - 120 of 303

Full-Text Articles in Biology

Effect Of Forest Age On Density Of Stream-Breeding Amphibians In Skamania County, Washington, Craig A. Steele May 2001

Effect Of Forest Age On Density Of Stream-Breeding Amphibians In Skamania County, Washington, Craig A. Steele

Biology

Because the ranges of stream-breeding amphibians in the Pacific Northwest occur partly on industrial timberlands, it is valuable to study population distributions of these animals in forest environments that rarely reach old growth status and are subject to timber harvest on a regular basis. To determine how short-term changes in forest age affect the density of stream-breeding amphibians, first-order streams located on private industrial timberlands in Skamania County, Washington, were sampled during the summers of 1998 and 1999. Species captured included Dicamptodon tenebrosus, Dicamptodon copei, Rhyacotriton cascadae, and Ascaphus truei. Regression tree analysis showed that relative …

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Switching Between Intensive And Extensive Searching In Predators Of Heterogeneously Distributed Prey, Zy Biesinger May 2001

Switching Between Intensive And Extensive Searching In Predators Of Heterogeneously Distributed Prey, Zy Biesinger

Biology

Many predators of patchily distributed prey are thought to increase their searching efficiency by alternating between extensive and intensive searching behavior. To test the effects of predator satiation and prey density on a ladybird's choice of searching mode, I performed experiments in which larvae of different hunger levels experienced different prey encounter rates. Using traditional measures, I found a beetle's satiation level to have no effect. The prey encounter rate had an effect on two of three traditional measures. Less traditional methods, fractal dimension analysis and Fourier slope analysis, supported the conclusions obtained using traditional measures. Analysis of movement patterns …

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Assemblages Of Spiders On Shrubs In Semiarid Environments: Experimental Models Of Shrub Architecture, Michael W. Heikkinen May 2001

Assemblages Of Spiders On Shrubs In Semiarid Environments: Experimental Models Of Shrub Architecture, Michael W. Heikkinen

Biology

Assemblages of spiders on big sagebrush are dominated by salticids. The pattern could result from many salticids in the colonist pool and random distribution as spiders disperse or a selection process by which spiders are choosing to remain on big sagebrush after initial colonization. Choices may be based on insect prey on the shrubs or related to the plant's physical attributes. Habitat structure has been associated with the distribution of many animals, and plant architecture influences the distribution of spiders. Models of big sagebrush were constructed to test plant architecture variables that spiders may use as cues in deciding to …

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Phylogenetic Relationships, Taxonomy, And Evolution Of Host Choice In Diadasia (Hymenoptera: Apoidea), Sedonia D. Sipes May 2001

Phylogenetic Relationships, Taxonomy, And Evolution Of Host Choice In Diadasia (Hymenoptera: Apoidea), Sedonia D. Sipes

Biology

I examined the phylogenetic relationships, taxonomy, and evolution of host choice in Diadasia, a genus of New World bees. Diadasia species are particularly interesting because they are considered pollen specialists. Females of each species are believed to provision their nests with pollen from only a few closely related plant taxa. At the same time, the choice of floral hosts within the genus is diverse, and includes five distantly related plant families: Malvaceae, Onagraceae, Convolvulaceae, Asteraceae, and Cactaceae. To estimate phylogenetic relationships within this group, I sequenced ~ 2 kb of the mitochondrial genes CO I and II and tRNA …

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Diversity, Distribution, And Abundance Of Flower-Visiting Apoidea (Hymenoptera) On Sand Dunes Of The West Desert Of Utah, Trent R. Toler May 2001

Diversity, Distribution, And Abundance Of Flower-Visiting Apoidea (Hymenoptera) On Sand Dunes Of The West Desert Of Utah, Trent R. Toler

Biology

Three habitats (dunes, mountain slopes, and mud flats) were surveyed for bees (Hymenoptera: Apoidea) in the Bonneville Basin in Utah on lands owned by the U.S. military, the Dugway Proving Grounds and the southern section of the Utah Testing and Training Range, in the summers of 1997 and 1998. Study of dune habitat was emphasized, as it is thought to be important for bees in arid climates, particularly in providing nesting substrate and sources of plant pollen and nectar. Species compositions of bees were determined using pan traps at 16 sites (in three habitats) in 1997, and at 5 dune …

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Avian Food Selection With Application To Pesticide Risk Assessment: Are Dead And Dessicated Insects A Desirable Food Source?, Jennifer M. Stafford May 2001

Avian Food Selection With Application To Pesticide Risk Assessment: Are Dead And Dessicated Insects A Desirable Food Source?, Jennifer M. Stafford

Biology

When evaluating avian pesticide exposure, a number of factors must be considered to form an accurate risk assessment. In the past, such assessments have been conducted with substantial uncertainty about avian consumption of exposed food items. One such uncertain factor is whether or not the avian species would consume contaminated invertebrates that were killed by a chemical application, and which may present an increasing concentration of the chemical as they desiccate over time. Therefore I asked the question: do birds select dead and desiccated insects as food items? I addressed the research question in two steps. First, a laboratory study …

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Variations In The Histamine Content Of Mink Testes Due To Injections Of Gonadotrophic Hormones And Application Of Free Radicals In Vitro, Grant I. Wilson May 2001

Variations In The Histamine Content Of Mink Testes Due To Injections Of Gonadotrophic Hormones And Application Of Free Radicals In Vitro, Grant I. Wilson

Biology

It was hypothesized that gonadotropic hormones and oxygen-derived free radicals affect histamine production in the testes. Luteinizing hormone, follicle stimulating hormone, prolactin, a combination of these three hormones, or saline (controls) were injected for either 4 or 7 days into seven wild-type (demi) and seven dark male mink per group. All mink were euthanized with carbon monoxide. Their testes were removed and frozen on dry ice. The histamine content was analyzed using radioimmunoassay. The control wild-type mink injected for either 4 or 7 days had histamine values of 8.15 μg/g and 7.56 μg/g, respectively. In wild-type mink, there was no …

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Storm-Related Suspended Particulate Matter In Little Westham Creek, John R. Jordan May 2001

Storm-Related Suspended Particulate Matter In Little Westham Creek, John R. Jordan

Master's Theses

Properties of a watershed regulate the amount of suspended particulate matter (SPM) in a stream. The present study examined relationships between storm-related SPM and impervious area and tree cover in the suburban watershed of Little Westham Creek, Richmond, Virginia during Summer and early Fall, 1999. SPM concentration, SPM discharge, and turbidity due to clay, silt and sand, and the areas of impervious surface and tree stand cover in the watershed were measured at three sites. SPM concentration, SPM discharge, and turbidity due to clay were greater upstream than downstream. The percentages of watershed area covered by impervious surfaces and tree …

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A Quantitative Histological Evaluation Of Articular Cartilage And Regenerated Tissue From A Stress-Shielded In Vivo Model, Jeremy Matthew Kupsco May 2001

A Quantitative Histological Evaluation Of Articular Cartilage And Regenerated Tissue From A Stress-Shielded In Vivo Model, Jeremy Matthew Kupsco

Master's Theses

Cartilage does not normally repair lesions. Cartilage induced to regenerate experimentally degenerates quickly, perhaps because stresses of articulation do not allow normal extracellular matrix to develop. I examined normal cartilage from dogs, pigs, rabbits, and humans, and canine patellar tissue regenerated in a stress-shielded environment. SEM of canine cartilage after trypsin digestion revealed meshworks of fibrils oriented with a bias normal to the surface in the deep zone, random in the middle zone, and parallel to the surface in the superficial zone. SEM after freeze-fracture revealed tubules of fibrils within the deep zone. I found no evidence of collagen arcades. …

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Natural History And Roosting Ecology Of The Eastern Pipistrelle, Pipistrellus Subflavus, Jacques Pierre Veilleux May 2001

Natural History And Roosting Ecology Of The Eastern Pipistrelle, Pipistrellus Subflavus, Jacques Pierre Veilleux

All-Inclusive List of Electronic Theses and Dissertations

A study concerning the natural history and roosting ecology of the eastern pipistrelle, Pipistrellus subtlavus, was conducted from 1997 to 2000, in southern Vigo County, Indiana. 111 Females began forming pre-maternity colonies during early May, and parturition began during late June. Pre-maternity colonies averaged 3.7 ± 1.9 individuals, and maternity colonies averaged 4.4 ± 2.4 individuals. Young pipistrelles first became volant during the third and fourth weeks of July. Pipistrelles were located in 59 roost trees. All roosts were located in foliage, either in clusters of dead leaves (n = 40) or in live foliage (n = 19). Oaks (Ouercus …

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Characterization Of A Non-Ribosomal Peptide From Agrobacterium Tumefaciens, Graham Strub May 2001

Characterization Of A Non-Ribosomal Peptide From Agrobacterium Tumefaciens, Graham Strub

Honors Theses

The current efforts underway to sequence the genome of Agrobacterium tumefaciens have led to the discovery of a large region of DNA (52kb) with a strong homology to several polyketide synthetase genes. This was a matter of great interest to the Agrobacterium project; no current literature documents the production of a polyketide or non:iibosomal peptide from Agrobacterium. Furthermore, the multi-domain enzymes coded by these polyketide synthetase genes in other bacterial species are responsible for synthesizing several toxins, many which act as antibiotic agents {8, 9, 12, 16). This was also of great interest, since Agrobacterium is not known to produce …

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Trophic Cascades, Nutrients, And Lake Productivity: Whole-Lake Experiments, Stephen R. Carpenter, Jonathan J. Cole, James R. Hodgson, James F. Kitchell, Michael L. Pace, Darren Bade, Kathryn L. Cottingham May 2001

Trophic Cascades, Nutrients, And Lake Productivity: Whole-Lake Experiments, Stephen R. Carpenter, Jonathan J. Cole, James R. Hodgson, James F. Kitchell, Michael L. Pace, Darren Bade, Kathryn L. Cottingham

Dartmouth Scholarship

Responses of zooplankton, pelagic primary producers, planktonic bacteria, and CO2 exchange with the atmosphere were measured in four lakes with contrasting food webs under a range of nutrient enrichments during a seven-year period. Prior to enrichment, food webs were manipulated to create contrasts between piscivore dominance and planktivore dominance. Nutrient enrichments of inorganic nitrogen and phosphorus exhibited ratios of N:P > 17:1, by atoms, to maintain P limitation. An unmanipulated reference lake, Paul Lake, revealed baseline variability but showed no trends that could confound the interpretation of changes in the nearby manipulated lakes. Herbivorous zooplankton of West Long Lake (piscivorous fishes) …

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Genetic Relationships Between Two Rare Plant Species, Aliciella Caespitosa And A. Tenuis, And Their Putative Progenitor, A. Subnuda, Carrie L. Mccracken May 2001

Genetic Relationships Between Two Rare Plant Species, Aliciella Caespitosa And A. Tenuis, And Their Putative Progenitor, A. Subnuda, Carrie L. Mccracken

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Isolated populations have potential to become new species that should have less genetic variation than their ancestors. Small populations are more likely to lose genetic variation, which is, thus, expected to be greater in ancestors. Aliciella caespitosa and A. tenuis, two endemic species, may be derived from small populations of A. subnuda, a widespread species. Chloroplast DNA sequences were used to test this hypothesis. Allozyme data were used to compare genetic variation and numbers of alleles. Chloroplast data do not support the proposed relationships between A. subnuda and the other two species. Allozyme data were not more variable …

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Hydrodynamic Properties Of Dna Polymerases, Angela Sherell Byrd May 2001

Hydrodynamic Properties Of Dna Polymerases, Angela Sherell Byrd

Honors Capstones

No abstract provided.

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Range Extensions Of The Seaweeds Codium Taylorii And Caulerpa Prolifera Into The Lower Laguna Madre, Texas, Hudson R. Deyoe, Donald L. Hockaday May 2001

Range Extensions Of The Seaweeds Codium Taylorii And Caulerpa Prolifera Into The Lower Laguna Madre, Texas, Hudson R. Deyoe, Donald L. Hockaday

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Between January 1999 and April 2000 two chlorophyte algae, Codium taylorii Silva and Caulerpa prolifera F. obovata (Forsskal) Lamouroux were found in the lower Laguna Madre (LLM). Both are coenocytic algae and are members of the chlorophyte class Bryopsidophyceae ( van den Hoek et al. 1995). The species descriptions in Taylor (1960) were used in the identification of the specimens. Her barium specimens have been deposited at the University of Texas- Pan American Coastal Studies Laboratory (accession numbers COlO - C. prolifera, COl 1 - C. taylorii) , University of California at Berkeley (UC 1753606 - C. taylorii) , University …

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Rna Levels And Activity Of Flowering Locus C Are Modified In Mixed Genetic Backgrounds Of Arabidopsis Thaliana, Michael Schläppi May 2001

Rna Levels And Activity Of Flowering Locus C Are Modified In Mixed Genetic Backgrounds Of Arabidopsis Thaliana, Michael Schläppi

Biological Sciences Faculty Research and Publications

Flowering time and FLOWERING LOCUS C (FLC) RNA levels were analyzed in different accessions of Arabidopsis thaliana and in mixed genetic backgrounds resulting from crosses between accessions. Dominant alleles of FRIGIDA (FRI) promote accumulation of FLC RNA, which in turn promotes late flowering. Although the coding regions of sequenced FLC alleles are identical, some accessions have genetically weak alleles that do not promote late flowering in the presence of FRI. In this study, a new weak allele of FLC with open reading frame identity to previously sequenced alleles was isolated from a Niederzenz (Nd) accession. …

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The Effects Of Parental Age And Housing Type On The Reproductive Success Of The Purple Martin (Progne Subis Subis), Jessica A. Eads May 2001

The Effects Of Parental Age And Housing Type On The Reproductive Success Of The Purple Martin (Progne Subis Subis), Jessica A. Eads

Electronic Theses and Dissertations

The reproductive success of the Purple Martin is dependent upon many factors. This study measured reproductive success of the Purple Martin (Progne subis subis) based on parental age and type of housing used. Reproductive parental ages consist of adults (experienced breeders) and subadults (first time breeders). Housing types included in this study were aluminum housing, wooden housing, plastic gourds, natural gourds, SuperGourds, and mailbox housing. The reproductive success was defined as the percentage of the original clutch that fledged. Study sites were located in Alabama, Indiana, North Carolina, Oklahoma, Tennessee, and Virginia. Pairs mating nonassortatively by age group …

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Systematic Relationships Of Natalid And Furipterid Bats, Based On Hyoid Morphology (Chiroptera: Natalidae And Furipteridae), Kosha N. Baxi '01 Apr 2001

Systematic Relationships Of Natalid And Furipterid Bats, Based On Hyoid Morphology (Chiroptera: Natalidae And Furipteridae), Kosha N. Baxi '01

Honors Projects

Themusculature of the hyoid regions of two species of bats (Order Chiroptera) from two separate families, Natalidae and Furipteridae, were examined using standard microscopic dissection techniques. Morphological variation was described and characters were scored and entered into the computer program PAUP, Phylogenetic Analysis Using Parsimony, along with characters of families previously examined by Griffiths. Cladistic analysis revealed support for the placement of Natalidae and Furipteridae together within the Superfamily Nataloidea, along with the families Thyropteridae and Myzopodidae, as recently proposed by Simmons (1998). The inclusion of Myzopodidae is surprising from a geographical standpoint. Myzopodids are endemic to Madagascar, while thyropterids, …

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Neotropical Nectar-Feeding Bats (Family Phyllostomidae) Revisited: Lingual Data Support A Recently-Proposed Molecular Phylogeny, Shawn De La Mar '01 Apr 2001

Neotropical Nectar-Feeding Bats (Family Phyllostomidae) Revisited: Lingual Data Support A Recently-Proposed Molecular Phylogeny, Shawn De La Mar '01

Honors Projects

From the early 1900s to the 1970s, all New World nectar-feeding bats were classified under the subfamily Glossophaginae. During the last few decades of the 20th century, however, several analyses supported the hypothesis that this taxon was an unnatural grouping. T. A. Griffiths (1982) proposed creating a new subfamily, the Lonchophyllinae, which would include Lonchophylla, Lionycteris, and Platalina, three genera formerly included in the Glossophaginae. This proposal raised significant controversy. A recent molecular study by R. J. Baker and colleagues (2000) examined the RAG2 gene DNA sequence in a large number of bats in the family Phyllostomidae, including Lonchophylla, Lionycteris, …

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Lipid Biochemistry Of House Wren Egg Yolk And Possible Effects On Incubation Period, Brian J. Payne '01 Apr 2001

Lipid Biochemistry Of House Wren Egg Yolk And Possible Effects On Incubation Period, Brian J. Payne '01

Honors Projects

House Wrens (Troglodytes aedon) are distributed throughout North and South America. As has been observed in many avian species, populations of House Wrens in the tropics have longer egg incubation periods than populations in temperate regions. The purpose of this study was to characterize incubation periods of a temperate population of House Wrens and to conduct a preliminary chemical analysis of the yellow and white yolk layers of House Wren eggs. The eggs were collected from a breeding population in Central Illinois from June-August 2000. Avian yolk is composed of yellow and white components, which are laid down in alternating …

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Litter Breakdown In Mountain Streams Affected By Mine Drainage: Biotic Mediation Of Abiotic Controls, Dev Niyogi, William M. Lewis Jr., Diane M. Mcknight Apr 2001

Litter Breakdown In Mountain Streams Affected By Mine Drainage: Biotic Mediation Of Abiotic Controls, Dev Niyogi, William M. Lewis Jr., Diane M. Mcknight

Biological Sciences Faculty Research & Creative Works

Breakdown of plant litter in streams was studied as an example of a major ecological process subject to change through multiple stresses associated with mine drainage. Rates of litter breakdown were measured at 27 sites in streams of the Rocky Mountains of Colorado, USA. Eight of the sites were pristine, and 19 were affected to varying degrees by mine drainage. The pH, concentrations of dissolved zinc, and deposition rates of metal oxides were measured in each stream. Rates of litter breakdown were estimated from changes in mass of willow leaves in litterbags. Biomass of shredding invertebrates in litterbags was monitored …

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The Scientific Foundations Of Habitat Conservation Plans: A Quantitative Assessment, Elaine K. Harding, Elizabeth E. Crone, Bret D. Elderd, Jonathan M. Hoekstra, Alexa J. Mckerrow, John D. Perrine, Jim Regetz, Leslie J. Rissler, Amanda G. Stanley, Eric L. Walters, Nceas Habitat Conservation Plan Working Group Apr 2001

The Scientific Foundations Of Habitat Conservation Plans: A Quantitative Assessment, Elaine K. Harding, Elizabeth E. Crone, Bret D. Elderd, Jonathan M. Hoekstra, Alexa J. Mckerrow, John D. Perrine, Jim Regetz, Leslie J. Rissler, Amanda G. Stanley, Eric L. Walters, Nceas Habitat Conservation Plan Working Group

Biological Sciences

The number of habitat conservation plans ( HCP) has risen dramatically since the first plan was written over 18 years ago. Until recently, no studies have quantitatively investigated the scientific foundations underlying these documents. As part of a larger study of HCPs, we examined 43 plans primarily to assess the availability and use of scientific data and secondarily to determine the extent of involvement by, and influence of, independent scientists within the process. Specifically, our analysis focused on five key steps taken when an HCP is developed: assessing status of a species, determining take, predicting the project effects, mitigating for …

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In Vivo Titration Of Mitomycin C Action By The Presence Of Four Escherichia Coli Genomic Regions On Multicopy Plasmid, Y. Wei, Amy Cheng Vollmer, R. A. Larossa Apr 2001

In Vivo Titration Of Mitomycin C Action By The Presence Of Four Escherichia Coli Genomic Regions On Multicopy Plasmid, Y. Wei, Amy Cheng Vollmer, R. A. Larossa

Biology Faculty Works

Mitomycin C (MMC), a DNA-damaging agent, is a potent inducer of the bacterial SOS response; surprisingly, it has not been used to select resistant mutants from wild-type Escherichia coli. MMC resistance is caused by the presence of any of four distinct E. coli genes (mdfA, gyrl, rob, and sdiA) on high-copy-number vectors. mdfA encodes a membrane efflux pump whose overexpression results in broad-spectrum chemical resistance. The gyrI (also called sbmC) gene product inhibits DNA gyrase activity in vitro, while the rob protein appears to function in transcriptional activation of efflux pumps. SdiA is a transcriptional activator of ftsQAZ genes involved …

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Bird Migration Through A Mountain Pass Studied With High Resolution Radar, Ceilometers, And Census, Timothy C. Williams , '64, J. M. Williams, P. G. Williams, P. Stokstad Apr 2001

Bird Migration Through A Mountain Pass Studied With High Resolution Radar, Ceilometers, And Census, Timothy C. Williams , '64, J. M. Williams, P. G. Williams, P. Stokstad

Biology Faculty Works

Autumnal migration was studied with high-resolution radar, ceilometer, and daily census in the area of Franconia Notch, a major pass in the northern Appalachian Mountains. Under synoptic conditions favorable for migration, broadfront movements of migrants toward the south passed over the mountains, often above a temperature inversion. Birds at lower elevations appeared to be influenced by local topography. Birds moving southwest were concentrated along the face of the mountain range. Birds appeared to deviate their flights to follow local topography through the pass. Specific migratory behavior was not associated with species or species groups. Under synoptic conditions unfavorable for southward …

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Determining Differences In The Spatial Distribution Of Forest Structure On The Kaibab Plateau: Implications For Forest Management And The Northern Goshawk, Ryan S. Miller Apr 2001

Determining Differences In The Spatial Distribution Of Forest Structure On The Kaibab Plateau: Implications For Forest Management And The Northern Goshawk, Ryan S. Miller

Other Publications in Wildlife Management

The Kaibab Plateau, in North Central Arizona, has undergone extensive change in the last 100 years due to land management practices such as logging, road building, and fire suppression. The northern goshawk (Accipiter gentilis) has been a center of controversy, due to the potential effects of silvicultural practices on goshawk breeding habitat (Reynolds-1983, Bloom et al 1986, Kennedy 1989, Crocker-Bedford 1990). Current and past research efforts on the Kaibab Plateau have mapped Goshawk nesting territories and temporal change in nesting behavior and success. However, these research efforts have not determined how long-term spatial changes in land-use activities that have influenced …

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Acid Phosphatase Activity In Human Breast Tumors, Reginald Halaby, Jafar Abdollahi, Minerva L. Martinez Apr 2001

Acid Phosphatase Activity In Human Breast Tumors, Reginald Halaby, Jafar Abdollahi, Minerva L. Martinez

Department of Biology Faculty Scholarship and Creative Works

We examined lysosomal participation in the degradation of tumor cells from human breast biopsies, utilizing the histochemical activity and localization of acid phosphatase (AP). Enzyme activities in benign and malignant lesions were compared. AP was faintly detected in normal mammary epithelia and was marked in malignant cells. The histochemical patterns of AP distribution in the breast tissues showed differences between normal and neoplastic cells. AP staining was more intense in ductal carcinoma in situ (DCIS) associated with invasive ductal carcinoma (IDC) cases compared to when IDC was present alone. These results suggest that non-invasive breast cancers, such as DCIS, may …

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Environmental Effects On Yield And Agronomic Traits Of Common Bean (Phaseolus Vulgaris L.), Tadesse Mebrahtu, Teklu Andebrhan, Ali Mohamed Apr 2001

Environmental Effects On Yield And Agronomic Traits Of Common Bean (Phaseolus Vulgaris L.), Tadesse Mebrahtu, Teklu Andebrhan, Ali Mohamed

Virginia Journal of Science

Common bean (Phaseolus vulgaris L.) demand is increasing with an alarming rate around the world, especially in Latin America, Africa, and Asia. Therefore, increase bean yield per hectare is the best way to meet the world demand rather than expansion of area under cultivation. The objectives of this experiment were to determine the genotypic variations for green bean and dry seed yield and magnitude of genotype x environment interaction effects on yield and yield components of common bean. Thirteen genotypes were planted during the 1992, 1994, and 1995 growing seasons. Genotypes were evaluated for green pod and seed …

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Isolation And Fusion Of Cotton Protoplasts, Michael H. Renfroe, Ronald C. Hartwig, Roberta H. Smith Apr 2001

Isolation And Fusion Of Cotton Protoplasts, Michael H. Renfroe, Ronald C. Hartwig, Roberta H. Smith

Virginia Journal of Science

Protoplasts were isolated from five species of Gossypium. Protoplast yield and viability were affected by incubation conditions, osmolarity, purification procedures, and cell source. Using an optimized procedure, highly viable protoplasts were isolated from cell suspensions, callus cultures, and leaf tissue of G. hirsutum, G. arboreum, G. klotzschianum, G. harknessii, and G. herbaceum. Protoplasts of G. harknessii were enucleated and successfully fused with protoplasts of G. hirsutum.

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Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski Apr 2001

Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski

Biology Faculty Research

Variation in thermal constraints on activity has been hypothesized to be an important ecological source of geographic variation in growth rates of juvenile eastern fence lizards Sceloporus undulatus. However, most of the evidence to support this hypothesis is either inferential or indirect. In this study, I quantitatively compared thermal constraints on activity and their relationship to growth rates of free-ranging juvenile fence lizards from two extremes of the range of variation in growth rate (Nebraska and New Jersey) used in a reciprocal transplant experiment. I also examined energy allocation made to growth and storage by yearling lizards. Reduced growth rates …

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Abp1 Is Required For Organized Cell Elongation And Division In Arabidopsis Embryogenesis, Hemayet Ullah Apr 2001

Abp1 Is Required For Organized Cell Elongation And Division In Arabidopsis Embryogenesis, Hemayet Ullah

Department of Biology Faculty Publications

To directly address the function of a putative auxin receptor designated ABP1, a reverse genetic approach was taken to identify and characterize ABP1 mutant alleles in Arabidopsis. A homozygous null mutation in ABP1 confers embryo lethality. Null mutant embryos develop normally until the early stages of the globular embryo but are unable to make the transition to a bilaterally symmetrical structure because cells fail to elongate. Cell division was also aberrant both in the suspensor and embryo proper. Antisense suppression of ABP1 in tobacco cells causes slow proliferation and eliminates auxin-induced cell elongation and reduces cell division. The complete lack …

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