Biology Commons^™

Antimicrobial Activities Of Lipodepsipeptide Syringopeptins, Mekki F. Bensaci

Biology

Many strains of the plant bacterium Pseudomonas syringae produce two major classes of cyclic lipodepsipeptides, the syringomycins and the syringopeptins. Four groups of small cyclic lipodepsipeptides are well known: the syringomycins, syringostatins, syringotoxins, and pseudomycins. They all have antimicrobial activities and tend to be more active against yeasts than against bacteria. The syringopeptins are lesser-known. The best-studied syringopeptins are SP22 and SP25. They possess antibacterial and antifungal activities, but their mechanisms of action and antimicrobial spectra are less studied. Saccharomyces cerevisiae sphingolipid and sterol biosynthetic mutants were used to investigate the mechanism of action of syringopeptins against fungi. Similarly to …

Rapid Evolution Of An Invasive Plant, John L. Maron, Montserrat Vilà, Riccardo Bommarco, Sarah Elmendorf, Paul Beardsley

Biological Sciences Faculty Publications

Exotic plants often face different conditions from those experienced where they are native. The general issue of how exotics respond to unfamiliar environments within their new range is not well understood. Phenotypic plasticity has historically been seen as the primary mechanism enabling exotics to colonize large, environmentally diverse areas. However, new work indicates that exotics can evolve quickly, suggesting that contemporary evolution may be more important in invasion ecology than previously appreciated. To determine the influence of contemporary evolution, phenotypic plasticity, and founder effects in affecting phenotypic variation among introduced plants, we compared the size, fecundity, and leaf area of …

Role Of Hydrophobic Residues In The Central Ectodomain Of Gp41 In Maintaining The Association Between Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Subunits Gp120 And Gp41, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

The interaction between the gp120 and gp41 subunits of the human immunodeficiency virus envelope glycoprotein serves to stabilize the virion form of the complex and to transmit receptor-induced conformational changes in gp120 to trigger the membrane fusion activity of gp41. In this study, we used site-directed mutagenesis to identify amino acid residues in the central ectodomain of gp41 that contribute to the stability of the gp120-gp41 association. We identified alanine mutations at six positions, including four tryptophan residues, which result in mutant envelope glycoprotein complexes that fail to retain gp120 on the cell surface. These envelope glycoproteins readily shed their …

Amebiasis And Comparison Of Microscopy To Elisa Technique In Detection Of Entamoeba Histolytica And Entamoeba Dispar, Clarence Lee

Department of Biology Faculty Publications

The analysis of records of amoebal infection in various hospitals in Kilimanjaro indicated frequent occurrence of amebiasis. The population over the age of five years had higher rate of amoebal infection compared to less than that of a five-year-old population; however, both age groups had similar patterns of amebiasis during January 1999 to June 2001. To investigate misdiagnosis of amebiasis, 226 patients (passive cases) in three hospitals and 616 individuals (active cases) from three different localities in Kilimanjaro were examined. In passive cases, the prevalences of Entamoeba histolytica and Entamoeba dispar were 1% and 7.3%, respectively. Among active cases, 1% …

Investigation Into The Spatial And Temporal Dynamics Of Stomatal Networks To Determine Whether Plants Perform Emergent, Distributed Computation, Jevin West

Biology

This research studies the spatial and temporal dynamics of stomatal patchiness in order to investigate the possibility that plants solve their problem of adjusting stomatal aperture in order to maximize CO₂ uptake while minimizing H₂O loss through an emergent, distributed computation. An extensive study is done on qualitative and quantitative characteristics of stomatal patchiness, and improved imaging techniques are developed to more fully capture the dynamics. In doing so, soliton-like structures were discovered. Sequences of chlorophyll fluorescence images of Xanthium strumarium leaves were then compared to image sequences of cellular computer simulations that solve problems via emergent, …

Analysis Of Phosphatidylinositol 4,5-Biphosphate And Inositol 1,4,5-Triphosphate In Dehydration And Cold-Stressed Arabidopsis Thaliana, James E. Thompson

Biology

During dehydration and cold stress, Arabidopsis thaliana (A. thaliana) plant cells mobilize calcium into their cytosol to elicit changes in gene expression that enable them to tolerate stress. It has been unclear how dehydration-stressed plant cells receive and transmit the signal that results in promoting increases in intracellular calcium concentration. Previously, phosphatidylinositol 4,5-biphosphate (PtdIns(4,5)P₂) and inositol 1,4,5 triphosphate (Ins(1,4,5)P₃) have been shown to accumulate and cause calcium mobilization in osmotically stressed A. thaliana. However, it was unknown whether the same occurred in plants exposed to other abiotic stresses. Data presented in this thesis …

Stoichiometric And Environmental Controls Of Consumer-Driven Nutrient Recycling In Steams, John D. Rothlisberger

Biology

I investigated the environmental control of consumer-mediated nutrient recycling (CNR) in sub-alpine streams by evaluating the effects of water temperature and food elemental composition on the rates and ratios of nitrogen (N) and phosphorus (P) excretion by macroinvertebrates. I predicted that biomass-specific excretion rates would be positively correlated with temperature whereas N:P ratios would primarily relate to food N:P ratio. I measured nutrient release by heptagenaiid larvae eating periphyton of varying elemental composition grown on nutrient-diffusing substrates. I hypothesized that skewed ratios of N:P release would result from differential retention of nutrients in the food. Excretion rates of N and …

Studies Of Saccharomyces Cerevisiae Sphingolipid C4 Hydroxylation And Ipt1 Function And Their Roles In Syringomycin E Action, Jolanta Idkowiak-Baldys

Biology

Sphingolipids are ubiquitous membrane components of all eukaryotic cells with important regulatory functions. The roles and biochemistry of two structural features of sphingolipids were studied: C4 hydroxylation and the addition of a terminal phosphoinositol. Structure-function studies of the yeast sphingolipid C4 long chain base hydroxylase (Sur2p) revealed that alanine replacement of any of eight histidine residues from three histidine-rich motifs, as well as additional histidine 249, eliminated hydroxylase activity. Seven additional residues were also found to be important elements of the active site. These results show that Sur2p is a member of the family of eight-histidine motif hydroxylases and desaturates. …

Dynamics Of Pectoral Fin Rowing In A Fish With An Extreme Rowing Stroke: The Threespine Stickleback (Gasterosteus Aculeatus), Jeffrey A. Walker Phd

Faculty Publications

The dynamics of pectoral fin rowing in the threespine stickleback are investigated by measuring the instantaneous force balance on freely swimming fish throughout the stroke cycle and comparing the measured forces with fin motions and an unsteady, blade-element model of pectoral fin propulsion. Both measured and modeled forces suggest that attached vortex and circulatory forces and not inertial (added mass) forces dominate the force balance. Peak forces occur at midstrokes. There is no evidence for large force peaks at the stroke transitions due to either rapid fin rotation (supination) or rapid fin closure against the body. The energetics of pectoral …

Alkaloids And Old Lace: Pollen Toxins Exclude Generalist Pollinators From Death Camas, Melissa Weber

Undergraduate Honors Capstone Projects

Many plants produce toxins to which specialist herbivores - typically insects - have evolved counter-adaptations, sometimes resulting in a co-evolutionary arms race. Although many non-social bee species are likewise taxonomic host specialists, the pollination guilds at their floral hosts frequently include diverse floral generalists as well, even on plants that are otherwise chemically defended. In this study, we show that pollen and nectar of foothills death camas (Toxicoscordion [=Zigadenus] paniculatum) contains zygacine, the alkaloid responsible for this plant's notorious mammalian toxicity. Many adults and larvae of the generalist solitary bee, Osmia lignaria (Megachilidae), were paralyzed and …

Natural History, Demography, And Home Range Characteristics Of A Southern California Population Of Phrynosoma Mcallii Inhabiting Atypical Habitat, Kirk Setser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phrynosoma mcallii inhabiting a topographically complex, sparsely vegetated, "mudhill" terrain site in southern California in 1999 and 2000 had low mortality rates, and small clutch sizes compared to previous data from this species. Females likely produced a single clutch of eggs in each year. Although this population occurs near a heavily used OHV trail, I did not detect any mortality due to OHV use.

Lizards did not center home ranges on obvious habitat features. Lizards maintained smaller home ranges and exhibited greater range fidelity than did lizards at other sites in other years. Phrynosoma mcallii share many area-use characters with …

Isolation And Characterization Of T-Dna Insertional Mutations In Arabidopsis Thaliana And Its Use In Determining Siamese, Taylor S. Gwin

Honors Capstones

No abstract provided.

Population Size And Movements Of Spotted Salamanders At South Holston Dam, Sullivan County, Tennessee., Eric Alexander Smith

Electronic Theses and Dissertations

In the Southern Appalachians, there are growing concerns about Spotted Salamanders (Ambystoma maculatum) due to habitat destruction and the uncertain future of their forested riparian habitat. In this study, I establish baseline data of a population of Spotted Salamanders so future monitoring of this population can be performed. The study site is located in northeastern Tennessee, just east of the city of Bristol. It is a vernal pond at the Osceola Island Recreation Area one mile below the South Holston Dam on Holston View Dam road. A drift fence was established completely around the perimeter of the vernal …

Rare, Threatened And Endangered Species Of Oregon (2004), James S. Kagan, Sue Vrilakas, Eleanor P. Gaines, Cliff Alton, Fern Mcarthur, Kuuipo Walsh, Eric Scheuering, John A. Christy, Jon Hak, Claudine Tobalske, Annie Weiland, Theresa Koloszar, Oregon Natural Heritage Information Center

Institute for Natural Resources Publications

Extinction is a natural process. Today, however, plant and animal species are disappearing world-wide at an accelerated pace. Based on current trends, half of the species on earth will be extinct within the next 100 years. The major cause of this phenomenon is large-scale destruction of native habitats, which has increased since European settlement began in the mid 1800's - in Oregon and throughout the New World.

Once lost, a species can never be recovered, and there is no way of knowing how useful it may have been. We do know that human beings and many of their industries depend …

Host Shifts In Phytophagous Insects: A Mathematical Modeling Perspective, Meenakshi Venkataraman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I explored changes in predator-prey system stability with the addition of spatial heterogeneity in prey density dependent mortality. The results indicated that this addition led to greater stability for all prey spatial distributions if prey was aggregated or loosely aggregated. These results indicated prey spatial distribution was critical to population stability. I next explored whether predator emigration under the above conditions would lead to a host shift. I used Chesson and Murdoch's templates of host density independent (HDI) aggregation and host density dependent (HDD) aggregation in predators as the basis for my metapopulation models. I varied prey density dependent mortality …

An Evaluation Of Submersed Aquatic Vegetation Transplanting Methods For Lake Pontchartrain Restoration, Donald Anthony Rodrigue Jr.

LSU New Orleans Theses and Dissertations

The general goals of this study were to evaluate transplant methods for Lake Pontchartrain submersed aquatic vegetation (SAV) restoration, and to compare survival and expansion of transplanted SAV among four sites. Two experiments were conducted from summer 2000 through spring 2001 at two north shore and two south shore sites in Lake Pontchartrain. Experiment 1 involved testing the effects of transplanting with matting, staples, exclosures, and interspecific interaction on survival and expansion of Ruppia maritima and Vallisneria americana transplants in Lake Pontchartrain. Experiment 2 involved testing the effects of transplanting with matting, staples, and plugs on Ruppia survival and expansion. …

Snow Avalanche Disturbance In Intermountain Spruce-Fir Forests And Implications For The Spruce Bark Beetle (Coleoptera: Scolytidae), Elizabeth G. Herbertson

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Spruce beetle outbreaks are the primary biotic disturbance affecting forests in the Intermountain spruce-fir zone. Major snow avalanches can produce large quantities of host material for spruce beetle colonization; however, few studies have examined the influence of avalanche disturbance on outbreak initiation. The purpose of my research was to investigate potential relationships between these two disturbance agents. In the first study, I used dendro-ecological analyses to date major avalanche years on the Wasatch Plateau in south-central Utah, and then determined what climate factors were associated with avalanche occurrence. The results indicated that mean January snowfall was significantly related to the …

Community Ecology Of Freshwater, Brackish And Salt Marshes Of The Rio Grande Delta, Frank W. Judd, Robert I. Lonard

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

Species composition and importance, species diversity and evenness, species richness, and community similarity are compared among 6 freshwater, 9 brackish and 11 salt marshes in the Rio Grande Delta. Community similarity is generally low among marshes, but salt marshes have a greater mean coefficient of similarity than brackish marshes. Species richness per marsh ranges from 15 to 31 for freshwater marshes, 7 to 24 for brackish marshes and 7 to 26 for salt marshes. Each freshwater marsh has a different dominant species. The first six species in importance in all three kinds of marshes contribute from 72.6 to 99.8% of …

Similarity Of Mammalian Body Size Across The Taxonomic Hierarchy And Across Space And Time, Felisa A. Smith, James H. Brown, John P. Haskell, S. Kathleen Lyons, John Alroy, Eric L. Charnov, Tamar Dayan, Brian J. Enquist, S.K. Morgan Ernest, Elizabeth A. Hadly, David Jablonski, Kate E. Jones, Dawn M. Kaufman, Pablo A. Marquet, Brian A. Maurer, Karl J. Niklas, Warren P. Porter, Kaustuv Roy, Bruce Tiffney, Michael R. Willig

Biology Faculty & Staff Publications

Although it is commonly assumed that closely related animals are similar in body size, the degree of similarity has not been examined across the taxonomic hierarchy. Moreover, little is known about the variation or consistency of body size patterns across geographic space or evolutionary time. Here, we draw from a data set of terrestrial, nonvolant mammals to quantify and compare patterns across the body size spectrum, the taxonomic hierarchy, continental space, and evolutionary time. We employ a variety of statistical techniques including "sib-sib" regression, phylogenetic autocorrelation, and nested ANOVA. We find an extremely high resemblance (heritability) of size among congeneric …

Physical Therapy And Womens' Health: Treating Low Back Pain During Pregnancy And Postpartum, Robin Borba

Whittier Scholars Program

This project is a close study of low back pain that women experience during pregnancy or postpartum. This study includes anatomy of the lower back, factors that affect Lumbar Lordosis, and physical and psychological changes during pregnancy. This project also includes an in depth analysis of lower back pain during pregnancy which includes symptoms, types, causes and risk factors. This paper demonstrates how physical therapy treats low back pain during pregnancy, labor and delivery, and postpartum and also includes a glossary, pictorial appendix and brochure.

Estimating Metazoan Divergence Times With A Molecular Clock, Kevin J. Peterson, Jessica B. Lyons, Kristin S. Nowak, Carter M. Takacs, Matthew J. Wargo, Mark A. Mcpeek

Dartmouth Scholarship

Accurately dating when the first bilaterally symmetrical animals arose is crucial to our understanding of early animal evolution. The earliest unequivocally bilaterian fossils are 555 million years old. In contrast, molecular-clock analyses calibrated by using the fossil record of vertebrates estimate that vertebrates split from dipterans (Drosophila) 900 million years ago (Ma). Nonetheless, comparative genomic analyses suggest that a significant rate difference exists between vertebrates and dipterans, because the percentage difference between the genomes of mosquito and fly is greater than between fish and mouse, even though the vertebrate divergence is almost twice that of the dipteran. Here we show …

Protection From The Effects Of Ultraviolet Radiation By The Encapsulating Structures Of Embryos Of Physa, A Freshwater Pulmonate Snail, Stacy Nielsen '04

Honors Projects

The genus Physa includes freshwater pulmonate snails that inhabit shallow environments well within depths penetrated by ultraviolet (UV) radiation. The distribution patterns of egg masses of Physa sp. indicate that the snails lay egg masses in sunlit areas and the masses are attached to rocks and debris such as leaves and twigs. Each mass consists of a viscous jelly covering that encases a variable number of embryos, and each of the embryos is individually surrounded by an egg capsule. Field-collected masses were found to have debris and epifaunal organisms attached to the jelly. Preliminary studies of the effect of UV …

Development Of A Tool To Facilitate Participation Of Maori In The Management Of Stream And River Health, Colin R. Townsend

Biological Sciences Faculty Research & Creative Works

A cultural health index (CHI) for streams was developed in a program of collaborative research involving members of Ngai Tahu (an iwi [tribe] within the South Island of New Zealand) and ecologists at Otago University. The aim was to provide a tool for effective participation of Maori in resource management decisions. Five cultural values are of central importance to the nature of the CHI: mauri (spiritual life force), mahinga kai (traditional resource harvesting), kaitiakitanga (guardianship obligation), ki uta ki tai (mountains-to-the-sea holistic philosophy), and wai taonga waters that are treasured). The CHI has three components. Forty-six stream sites in two …

Variability In Spectral Backscatter Estimated From Satellites And Its Relation To In Situ Measurements In Optically Complex Coastal Waters, Mark A. Moline, Robert Arnone, Trisha Bergmann, Scott Glenn, Matthew J. Oliver, Cristina Orrico, Oscar Schofield, Sasha Tozzi

Biological Sciences

A large database of in situ bio-optical measurements was collected at the Long-term Ecosystem Observatory off the southern coast of New Jersey, USA. In part, the research effort focused on reconciling in situ estimates with satellite-derived estimates of the inherent optical properties (IOP). At 442 nm, in situ absorption values ranged from less than 0.2 to over 1.5 inverse metres. Satellite estimates of backscatter ranged from 0.002 to 0.03 inverse metres at 442 nm and showed significant variability in time and space during July 1999, reflecting the recurrent high frequency events that characterize the region—wind-mixing, storms and coastal upwelling. Despite …

Micrococcus Luteus - Survival In Amber, C. L. Greenblatt, J. Baum, B. Y. Klein, S. Nachshon, V. Koltunov, R. J. Cano

Biological Sciences

A growing body of evidence now supports the isolation of microorganisms from ancient materials. However, questions about the stringency of extraction methods and the genetic relatedness of isolated organisms to their closest living relatives continue to challenge the authenticity of these ancient life forms. Previous studies have successfully isolated a number of spore-forming bacteria from organic and inorganic deposits of considerable age whose survival is explained by their ability to enter suspended animation for extended periods of time. However, despite a number of putative reports, the isolation of non-spore-forming bacteria and an explanation for their survival have remained enigmatic. Here …

Variability In Measured And Modelled Remote Sensing Reflectance For Coastal Waters At Leo-5, Sasha Tozzi, Oscar Schofield, Trisha Bergmann, Mark A. Moline, Robert Arnone

Biological Sciences

A large database of in situ bio-optical measurements were collected at the LEO-15 (Long-term Ecosystem Observatory) off the southern coast of New Jersey, USA. The data were used to quantify the impact of coastal upwelling on near-shore bulk apparent (AOP) and inherent (IOP) optical properties. There was good qualitative agreement between the AOPs and IOPs in space and time. The measured IOPs were used as inputs to the Hydrolight radiative transfer model (RTE). Estimated spectral AOPs from the RTE were strongly correlated (generally R²>0.80) to measured AOPs. If optical closure between in-water measurements was achieved then the RTE …

Seasonal Dynamics Of Shallow-Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Chris Frazar, Matthias Rillig, Johnnie N. Moore, William E. Holben

Biological Sciences Faculty Publications

Heavy metals contaminate numerous freshwater streams and rivers worldwide. Previous work by this group demonstrated a relationship between the structure of hyporheic microbial communities and the fluvial deposition of heavy metals along a contamination gradient during the fall season. Seasonal variation has been documented in microbial communities in numerous terrestrial and aquatic environments, including the hyporheic zone. The current study was designed to assess whether relationships between hyporheic microbial community structure and heavy-metal contamination vary seasonally by monitoring community structure along a heavy-metal contamination gradient for more than a year. No relationship between total bacterial abundance and heavy metals was …

Gc Fractionation Enhances Microbial Community Diversity Assessment And Detection Of Minority Populations Of Bacteria By Denaturing Gradient Gel Electrophoresis, William Holben, Keving P. Feris, Anu Kettunen, Juha H. A. Apajalahti

Biological Sciences Faculty Publications

Effectively and accurately assessing total microbial community diversity is one of the primary challenges in modern microbial ecology. This is particularly true with regard to the detection and characterization of unculturable populations and those present only in low abundance. We report a novel strategy, GC fractionation combined with denaturing gradient gel electrophoresis (GC-DGGE), which combines mechanistically different community analysis approaches to enhance assessment of microbial community diversity and detection of minority populations of microbes. This approach employs GC fractionation as an initial step to reduce the complexity of the community in each fraction. This reduced complexity facilitates subsequent detection of …

Fisheries Occasional Publication No. 6 - Anglers Guide To Assessing Reproductive Stage In Fish, Kim Smith, Mike Mackie, Department Of Fisheries Western Australia

Fisheries Occasional Publications

What is a gonad?

"Gonad" is a general term for a reproductive organ, and is used to describe both ovaries and testes. In male and female fish, the gonad is an elongated organ lying along the upper wall of the gut cavity (i.e. running immediately under the vertebral column). The gonad gonad has 2 lobes. Both lobes are attached to the body near the anus and extend forward inside the gut cavity.

As fish gonads ripen, they become larger, heavier and change colour. Immature and undeveloped adult gonads are very small, strap-like in shape, pinkish in colour and translucent (i.e. …

Recently Elected Fellows

Virginia Journal of Science

The Virginia Academy of Science elected three scientists at the 2004 Banquet: Harold G Marshall, Rosemary Barra, and Arthur F. Conway.