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Biological Sciences Faculty Publications

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Articles 901 - 930 of 1156

Full-Text Articles in Biology

Algal Composition And Abundance In The Neuston Surface Micro Layer From A Lake And Pond In Virginia (U.S.A.), Lubomira Burchardt, Harold G. Marshall Jan 2003

Algal Composition And Abundance In The Neuston Surface Micro Layer From A Lake And Pond In Virginia (U.S.A.), Lubomira Burchardt, Harold G. Marshall

Biological Sciences Faculty Publications

A comparative study was conducted that characterized the algae within the neuston, ca 2 mm below the surface, and the algae in the water column from two freshwater habitats. There were significant differences in total algal abundance and the abundance of diatoms, cyanoprokaryotes, and chlorophytes between the neuston and water column algae of these two regions during each season and at both sites. The pond neuston was dominated by chlorophytes, with total algal abundance ranging seasonally from 0.6 to 59.6 x 10-3 cells ml-1 compared to water column algal concentrations of 4.1 to 40.4 x 10-3 cells ml-1. …

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Characteristic Genome Rearrangements In Experimental Evolution Of Saccharomyces Cerevisiae, Maitreya J. Dunham, Hassan Badrane, Tracy Ferea, Julian Adams, Patrick O. Brown, Frank Rosenzweig, David Botstein Dec 2002

Characteristic Genome Rearrangements In Experimental Evolution Of Saccharomyces Cerevisiae, Maitreya J. Dunham, Hassan Badrane, Tracy Ferea, Julian Adams, Patrick O. Brown, Frank Rosenzweig, David Botstein

Biological Sciences Faculty Publications

Genome rearrangements, especially amplifications and deletions, have regularly been observed as responses to sustained application of the same strong selective pressure in microbial populations growing in continuous culture. We studied eight strains of budding yeast (Saccharomyces cerevisiae) isolated after 100-500 generations of growth in glucose-limited chemostats. Changes in DNA copy number were assessed at single-gene resolution by using DNA microarray-based comparative genomic hybridization. Six of these evolved strains were aneuploid as the result of gross chromosomal rearrangements. Most of the aneuploid regions were the result of translocations, including three instances of a shared breakpoint on chromosome 14 immediately adjacent to …

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Plasticity And Genetic Diversity May Allow Saltcedar To Invade Cold Climates In North America, Jason P. Sexton, J. K. Mckay, Anna Sala Dec 2002

Plasticity And Genetic Diversity May Allow Saltcedar To Invade Cold Climates In North America, Jason P. Sexton, J. K. Mckay, Anna Sala

Biological Sciences Faculty Publications

Two major mechanisms have been proposed to explain the ability of introduced populations to colonize over large habitat gradients, despite significant population bottlenecks during introduction: (1) Broad environmental tolerance-successful invaders possess life history traits that confer superior colonizing ability and/or phenotypic plasticity, allowing acclimation to a wide range of habitats. (2) Local adaptation-successful invaders rapidly adapt to local selective pressures. However, even with bottlenecks, many introduced species exhibit surprisingly high levels of genetic variation and thus the potential for evolutionary increases in invasive traits and plasticity. Here we assess the invasive potential of Tamarix ramosissima, by examining the degree of …

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Convergent Demographic Effects Of Insect Attack On Related Thistles In Coastal Vs. Continental Dunes, John L. Maron, Julie K. Combs, Svata M. Louda Dec 2002

Convergent Demographic Effects Of Insect Attack On Related Thistles In Coastal Vs. Continental Dunes, John L. Maron, Julie K. Combs, Svata M. Louda

Biological Sciences Faculty Publications

Insect herbivory is common, but the conditions under which it reduces the fitness and population size of plants remain poorly understood. We quantified population-level impacts of floral herbivory by specialized insects on cobweb thistle (Cirsium occidentale var. occidentale) in a California coastal dune ecosystem, and then compared these demographic effects to those published for Platte thistle (Cirsium canescens) in similarly designed exclusion experiments in the continental sand dune ecosystem in the Great Plains. As a separate test of the strength of the seed-to-seedling linkage, we quantified seedling establishment rates in seed addition plots and compared these …

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Groel Expression In Gyrb Mutants Of Borrelia Burgdorferi, Janet Alverson, D. Scott Samuels Nov 2002

Groel Expression In Gyrb Mutants Of Borrelia Burgdorferi, Janet Alverson, D. Scott Samuels

Biological Sciences Faculty Publications

GroEL protein and groEL mRNA transcript were up-regulated in gyrB mutants of Borrelia burgdorferi, a causative agent of Lyme disease. Furthermore, the protein and transcript levels in gyrB mutants were greater than those in experimentally heat-shocked cultures of wild-type B. burgdorferi. Circular DNA in the gyrB mutants was more relaxed than in wild-type cells, although groEL is on the linear chromosome of B. burgdorferi. To our knowledge, this is the first evidence, albeit indirect, for the effect of DNA topology on gene expression from a linear DNA molecule in a bacterium.

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Culture-Independent Microbial Community Analysis Reveals That Inulin In The Diet Primarily Affects Previously Unknown Bacteria In The Mouse Cecum, Juha H. A. Apajalahti, Hannele Kettunen, Anu Kettunen, William E. Holben, Päivi H. Nurminen, Nina Rautonen, Marja Mutanen Oct 2002

Culture-Independent Microbial Community Analysis Reveals That Inulin In The Diet Primarily Affects Previously Unknown Bacteria In The Mouse Cecum, Juha H. A. Apajalahti, Hannele Kettunen, Anu Kettunen, William E. Holben, Päivi H. Nurminen, Nina Rautonen, Marja Mutanen

Biological Sciences Faculty Publications

Inulin is a well-known fructose-based prebiotic which has been shown to stimulate the growth of bifidobacteria, a bacterial group generally considered beneficial for intestinal health. In the present study, we analyzed inulin-associated shifts in the total bacterial community of wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene by using DNA-based approaches independent of bacterial culturability. Mice were fed a high-fat, nonfiber diet with or without inulin inclusion at a 10% (wt/wt) concentration. Cecal contents were analyzed after 0, 3, and 9 weeks on the experimental diets. Inulin inclusion significantly affected the total bacterial community …

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Molecular Mechanisms Of Metabolic Arrest: Life In Limbo (Book Review), Bernard Rees Oct 2002

Molecular Mechanisms Of Metabolic Arrest: Life In Limbo (Book Review), Bernard Rees

Biological Sciences Faculty Publications

No abstract provided.

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Distinct Interactions Of Gtp, Utp, And Ctp With G(S) Proteins, Andreas Gille, Hui-Yu Liu, Stephen R. Sprang, Roland Seifert Sep 2002

Distinct Interactions Of Gtp, Utp, And Ctp With G(S) Proteins, Andreas Gille, Hui-Yu Liu, Stephen R. Sprang, Roland Seifert

Biological Sciences Faculty Publications

Early studies showed that in addition to GTP, the pyrimidine nucleotides UTP and CTP support activation of the adenylyl cyclase (AC)-stimulating G(s) protein. The aim of this study was to elucidate the mechanism by which UTP and CTP support G(s) activation. As models, we used S49 wild-type lymphoma cells, representing a physiologically relevant system in which the beta(2)-adrenoreceptor (beta(2)AR) couples to G(s), and Sf9 insect cell membranes expressing beta(2)AR-Galpha(s) fusion proteins. Fusion proteins provide a higher sensitivity for the analysis of beta(2)AR-G(s) coupling than native systems. Nucleoside 5'-triphosphates (NTPs) supported agonist-stimulated AC activity in the two systems and basal AC …

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Review Of: Riverine Flood Plains: Present State And Future Trends, Klement Tockner, Jack Arthur Stanford Sep 2002

Review Of: Riverine Flood Plains: Present State And Future Trends, Klement Tockner, Jack Arthur Stanford

Biological Sciences Faculty Publications

Natural flood plains are among the most biologically productive and diverse ecosystems on earth. Globally, riverine flood plains cover > 2 x 10(6) km(2), however, they are among the most threatened ecosystems. Floodplain degradation is closely linked to the rapid decline in freshwater biodiversity; the main reasons for the latter being habitat alteration, flow and flood control, species invasion and pollution. In Europe and North America, up to 90% of flood plains are already 'cultivated' and therefore functionally extinct. In the developing world, the remaining natural flood plains are disappearing at an accelerating rate, primarily as a result of changing hydrology. …

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Current Issues In Forensic Dna Profiling, Dan E. Krane Sep 2002

Current Issues In Forensic Dna Profiling, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.

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Cosolvent-Induced Transformation Of A Death Domain Tertiary Structure, Tsan Xiao, Kevin H. Gardner, Stephen R. Sprang Aug 2002

Cosolvent-Induced Transformation Of A Death Domain Tertiary Structure, Tsan Xiao, Kevin H. Gardner, Stephen R. Sprang

Biological Sciences Faculty Publications

The death domain (DD) of the protein kinase Pelle adopts a six-helix bundle fold in the crystal structure of the complex with its dimerization partner, Tube-DD. However, in crystals obtained from a solution of 45% 2-methyl-2,4-pentanediol (MPD), the C-terminal half of Pelle-DD folds into a single helix, and the N-terminal half of the molecule is disordered. The helical segment forms an antiparallel dimer with the corresponding helix of a symmetry-related molecule, and together they form extensive lattice interactions similar in number, composition, and buried surface to those in the six-helix bundle of the native fold. Secondary structure analysis by heteronuclear …

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The Neisseria Lipooligosaccharide-Specific Alpha-2,3-Sialyltransferase Is A Surface-Exposed Outer Membrane Protein, Dawn M. Shell, Lisa Chiles, Ralph C. Judd, Samar Seal, Richard F. Rest Jul 2002

The Neisseria Lipooligosaccharide-Specific Alpha-2,3-Sialyltransferase Is A Surface-Exposed Outer Membrane Protein, Dawn M. Shell, Lisa Chiles, Ralph C. Judd, Samar Seal, Richard F. Rest

Biological Sciences Faculty Publications

Neisseria gonorrhoeae and Neisseria meningitidis express an similar to43-kDa alpha-2,3-sialyltransferase (Lst) that sialylates the surface lipooligosaccharide (LOS) by using exogenous (in all N. gonorrhoeae strains and some N. meningitidis serogroups) or endogenous (in other N. meningitidis serogroups) sources of 5'-cytidinemonophospho-N-acetylneuraminic acid (CMP-NANA). Sialylation of LOS can protect N. gonorrhoeae and N. meningitidis from complement-mediated serum killing and from phagocytic killing by neutrophils. The precise subcellular location of Lst has not been determined. We confirm and extend previous studies by demonstrating that Lst is located in the outer membrane and is surface exposed in both N. gonorrhoeae and N. meningitidis. Western …

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Genetic Evidence That Interhelical Packing Interactions In The Gp41 Core Are Critical For Transition Of The Human Immunodeficiency Virus Type 1 Envelope Glycoprotein To The Fusion-Active State, Kathryn E. Follis, Scott J. Larson, Min Lu, Jack H. Nunberg Jul 2002

Genetic Evidence That Interhelical Packing Interactions In The Gp41 Core Are Critical For Transition Of The Human Immunodeficiency Virus Type 1 Envelope Glycoprotein To The Fusion-Active State, Kathryn E. Follis, Scott J. Larson, Min Lu, Jack H. Nunberg

Biological Sciences Faculty Publications

The envelope glycoprotein complex (gp120-gp41) of human immunodeficiency virus type 1 (HIV-1) promotes the fusion of viral and cellular membranes through formation of the fusion-active six-helix bundle in the gp41 ectodomain. This gp41 core structure consists of three C-terminal helices packed in an antiparallel manner into hydrophobic grooves on the surface of the N-terminal trimeric coiled coil. Alanine mutations that destabilize the N- and C-terminal interhelical packing interactions also reduce viral infectivity. Here we show that viruses bearing these mutations exhibit a marked potentiation of inhibition by peptides that make up the gp41 core. By contrast, these viruses are unchanged …

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Computational Simulation Of The Docking Of Prochlorothrix Hollandica Plastocyanin To Photosystem I: Modeling The Electron Transfer Complex, George S. Bullerjahn, Neocles B. Leontis, Eugene Myshkin Jun 2002

Computational Simulation Of The Docking Of Prochlorothrix Hollandica Plastocyanin To Photosystem I: Modeling The Electron Transfer Complex, George S. Bullerjahn, Neocles B. Leontis, Eugene Myshkin

Biological Sciences Faculty Publications

We have used several docking algorithms (GRAMM, FTDOCK, DOT, AUTODOCK) to examine protein-protein interactions between plastocyanin (Pc)/photosystem I (PSI) in the electron transfer reaction. Because of the large size and complexity of this system, it is faster and easier to use computer simulations than conduct x-ray crystallography or nuclear magnetic resonance experiments. The main criterion for complex selection was the distance between the copper ion of Pc and the P700 chlorophyll special pair. Additionally, the unique tyrosine residue (Tyr(12)) of the hydrophobic docking surface of Prochlorothrix hollandica Pc yields a specific interaction with the lumenal surface of PSI, thus providing …

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Threshold Evolution In Exotic Populations Of A Polyphenic Beetle, Armin P. Moczek, John Hunt, Douglas J. Emlen, Leigh W. Simmons May 2002

Threshold Evolution In Exotic Populations Of A Polyphenic Beetle, Armin P. Moczek, John Hunt, Douglas J. Emlen, Leigh W. Simmons

Biological Sciences Faculty Publications

Polyphenic development is thought to play an important role in the evolution of phenotypic diversity and morphological novelties, yet the evolution of polyphenisms has rarely been documented in natural populations. Here we compare the morphologies of male dung beetles (Onthophagus taurus; Coleoptera: Scarabaeidae) from populations introduced to Australia and the eastern United States. Males in this species express two alternative morphologies in response to larval feeding conditions. Males encountering favourable conditions grow larger than a threshold body size and develop a pair of horns on their heads, whereas males that encounter poor conditions do not reach this threshold size and …

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The Fitness Consequences Of Interspecific Eavesdropping Between Plants, Richard Karban, John L. Maron May 2002

The Fitness Consequences Of Interspecific Eavesdropping Between Plants, Richard Karban, John L. Maron

Biological Sciences Faculty Publications

Although many ecologists have discounted the possibility of communication between plants, recent work demonstrates that wild tobacco plants with experimentally clipped sagebrush neighbors suffer less leaf herbivory than tobacco controls with unclipped neighbors. In this report, we examine the fitness consequences of resistance induced by eavesdropping. Annual tobacco plants with clipped sagebrush neighbors produced more flowers and seed-bearing capsules than plants with unclipped neighbors although these performance measures varied considerably over the five years of the study. Tobacco plants with clipped neighbors also suffered more frost damage than controls in one year. There was no indication that eavesdropping was more …

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Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway Feb 2002

Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway

Biological Sciences Faculty Publications

Theory on costs of plant defense against herbivory in stressful environments predicts that costs should increase when competition is intense. This amplifies a fundamental dilemma that plants are thought to face: allocate limited resources to grow fast enough to compete, or invest these resources in secondary metabolites to maintain defense. We studied costs associated with genetic and environmental variation in secondary metabolite production of Brassica rapa in the presence and absence of the generalist competitor Lolium perenne. We used experimental quantitative genetics (artificial selection) to manipulate genetic variation, and herbivore-induction treatments to produce environmental variation in myrosinase and glucosinolate …

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Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang Jan 2002

Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

No abstract provided.

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Glass Capillary Tube Feeding: A Method For Infecting Nymphal Ixodes Scapularis (Acari: Ixodidae) With The Lyme Disease Spirochete Borrelia Burgdorferi, Anne H. Broadwater, Daniel E. Sonenshine, Wayne L. Hynes, Shane Ceraul, Aravinda M. De Silva Jan 2002

Glass Capillary Tube Feeding: A Method For Infecting Nymphal Ixodes Scapularis (Acari: Ixodidae) With The Lyme Disease Spirochete Borrelia Burgdorferi, Anne H. Broadwater, Daniel E. Sonenshine, Wayne L. Hynes, Shane Ceraul, Aravinda M. De Silva

Biological Sciences Faculty Publications

We evaluated an artificial capillary feeding method to infect nymphal Ixodes scapularis (Say) ticks with Borrelia burgdorferi, the causative agent of Lyme disease. Thirty to 70% of the nymphs were infected after feeding for 2.5 h from glass capillary tubes filled with a solution of spirochetes. Capillary infection was stable and persisted in the nymphs for at least 10 d after feeding. Capillary feeding also maintained natural vector competence patterns because I. scapularis ticks acquired infection unlike Dermacentor variablis (Say), which did not become infected. Capillary infected I. scapularis nymphs were capable of transmitting the infection to naive mice …

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In Vivo Effect Of Leukemia Inhibitory Factor (Lif) And An Anti-Lif Polyclonal Antibody On Murine Embryo And Fetal Development Following Exposure At The Time Of Transcervical Blastocyst Transfer, Michael H. Mitchell, R. James Swanson, Sergio Oehninger Jan 2002

In Vivo Effect Of Leukemia Inhibitory Factor (Lif) And An Anti-Lif Polyclonal Antibody On Murine Embryo And Fetal Development Following Exposure At The Time Of Transcervical Blastocyst Transfer, Michael H. Mitchell, R. James Swanson, Sergio Oehninger

Biological Sciences Faculty Publications

Leukemia inhibitory factor (LIF) enhances in vitro murine preimplantation development in a time- and dose-dependent fashion. Knockout experiments have demonstrated that endometrial LIF is essential for in vivo murine implantation. We assessed the impact of LIF and an anti-LIF polyclonal antibody (pab) on in vivo development and developed a novel and successful nonsurgical method of embryo transfer for this species, a transcervical blastocyst transfer technique. The objectives of this study were to evaluate the effects of LIF and the anti-LIF pab on 1) implantation, resorption, pregnancy, and viability rates and 2) the overall structural and skeletal development. Two-cell embryos were …

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Percent G+C Profiling Accurately Reveals Diet-Related Differences In The Gastrointestinal Microbial Community Of Broiler Chickens, Juha H. A. Apajalahti, Anu Kettunen, Michael R. Bedford, William E. Holben Dec 2001

Percent G+C Profiling Accurately Reveals Diet-Related Differences In The Gastrointestinal Microbial Community Of Broiler Chickens, Juha H. A. Apajalahti, Anu Kettunen, Michael R. Bedford, William E. Holben

Biological Sciences Faculty Publications

Broiler chickens from eight commercial farms in Southern Finland were analyzed for the structure of their gastrointestinal microbial community by a nonselective DNA-based method, percent G+C-based profiling. The bacteriological impact of the feed source and in-farm whole-wheat amendment of the diet was assessed by percent G+C profiling. Also, a phylogenetic 16S rRNA gene (rDNA)-based study was carried out to aid in interpretation of the percent G+C profiles. This survey showed that most of the 16S rDNA sequences found could not be assigned to any previously known bacterial genus or they represented an unknown species of one of the taxonomically heterogeneous …

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Isolation And Characterization Of A Novel As(V)-Reducing Bacterium: Implications For Arsenic Mobilization And The Genus Desulfitobacterium, Allison Niggemyer, Stefan Spring, Erko Stackebrandt, Frank Rosenzweig Dec 2001

Isolation And Characterization Of A Novel As(V)-Reducing Bacterium: Implications For Arsenic Mobilization And The Genus Desulfitobacterium, Allison Niggemyer, Stefan Spring, Erko Stackebrandt, Frank Rosenzweig

Biological Sciences Faculty Publications

Dissimilatory arsenate-reducing bacteria have been implicated in the mobilization of arsenic from arsenic-enriched sediments. An As(V)-reducing bacterium, designated strain GBFH, was isolated from arsenic-contaminated sediments of Lake Coeur d'Alene, Idaho. Strain GBFH couples the oxidation of formate to the reduction of As(V) when formate is supplied as the sole carbon source and electron donor. Additionally, strain GBFH is capable of reducing As(V), Fe(III), Se(VI), Mn(IV) and a variety of oxidized sulfur species. 16S ribosomal DNA sequence comparisons reveal that strain GBFH is closely related to Desulfitobacterium hafniense DCB-2T and Desulfitobacterium frappieri PCP-1T. Comparative physiology demonstrates that D …

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Facilitation And Competition On Gradients In Alpine Plant Communities, Philippe Choler, Richard Michalet, Ragan M. Callaway Dec 2001

Facilitation And Competition On Gradients In Alpine Plant Communities, Philippe Choler, Richard Michalet, Ragan M. Callaway

Biological Sciences Faculty Publications

We conducted a neighbor removal experiment in natural alpine plant communities of the southwestern Alps to test for the relative importance of competitive and facilitative interactions along elevational and topographical gradients. The experimental sites were chosen to encompass most of the floristic diversity observed along gradients of elevation and topography, which are the two main ecological gradients associated with alpine plant communities in the western Alps. The effects of neighbor removal on the survival, aboveground biomass, and reproduction of five target species were tested at each of six experimental sites. Using biomass data, we calculated relative competitive index (RCI) and …

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Structural And Functional Analysis Of Interhelical Interactions In The Human Immunodeficiency Virus Type 1 Gp41 Envelope Glycoprotein By Alanine-Scanning Mutagenesis, Min Lu, Marisa O. Stoller, Shilong Wang, Jie Liu, Melinda B. Fagan, Jack H. Nunberg Nov 2001

Structural And Functional Analysis Of Interhelical Interactions In The Human Immunodeficiency Virus Type 1 Gp41 Envelope Glycoprotein By Alanine-Scanning Mutagenesis, Min Lu, Marisa O. Stoller, Shilong Wang, Jie Liu, Melinda B. Fagan, Jack H. Nunberg

Biological Sciences Faculty Publications

Membrane fusion by human immunodeficiency virus type 1 (HIV-1) is promoted by the refolding of the viral envelope glycoprotein into a fusion-active conformation. The structure of the gp41 ectodomain core in its fusion-active state is a trimer of hairpins in which three antiparallel carboxyl-terminal helices pack into hydrophobic grooves on the surface of an amino-terminal trimeric coiled coil. In an effort to identify amino acid residues in these grooves that are critical for gp41 activation, we have used alanine-scanning mutagenesis to investigate the importance of individual side chains in determining the biophysical properties of the gp41 core and the membrane …

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Structure Of The Rgrgs Domain Of P115rhogef, Zhe Chen, Clark D. Wells, Paul C. Sternweis, Stephen R. Sprang Sep 2001

Structure Of The Rgrgs Domain Of P115rhogef, Zhe Chen, Clark D. Wells, Paul C. Sternweis, Stephen R. Sprang

Biological Sciences Faculty Publications

p115RhoGEF, a guanine nucleotide exchange factor for Rho GTPase, is also a GTPase activating protein (GAP) for G12 and G13 heterotrimeric Gα subunits. Near its N-terminus, p115RhoGEF contains a domain (rgRGS) with remote sequence identity to RGS (regulators of G protein signaling) domains. The rgRGS domain is necessary but not sufficient for the GAP activity of p115RhoGEF. The 1.9 Å resolution crystal structure of the rgRGS domain shows structural similarity to RGS domains but possesses a C-terminal extension that folds into a layer of helices that pack against the hydrophobic core of the domain. Mutagenesis experiments show that …

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Transduction By Phi Bb-1, A Bacteriophage Of Borrelia Burgdorferi, Christian H. Eggers, Betsy J. Kimmel, James L. Bono, Abdallah F. Elias, Patricia Rosa, D. Scott Samuels Aug 2001

Transduction By Phi Bb-1, A Bacteriophage Of Borrelia Burgdorferi, Christian H. Eggers, Betsy J. Kimmel, James L. Bono, Abdallah F. Elias, Patricia Rosa, D. Scott Samuels

Biological Sciences Faculty Publications

We previously described a bacteriophage of the Lyme disease agent Borrelia burgdorferi designated phi BB-1. This phage packages the host complement of the 32-kb circular plasmids (cp32s), a group of homologous molecules found throughout the genus Borrelia. To demonstrate the ability of phi BB-1 to package and transduce DNA, a kanamycin resistance cassette was inserted into a cloned fragment of phage DNA, and the resulting construct was transformed into B. burgdorferi CA-11.2A cells. The kan cassette recombined into a resident cp32 and was stably maintained. The cp32 containing the kan cassette was packaged by phi BB-1 released from this B. …

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Restoring Enriched Grasslands: Effects Of Mowing On Species Richness, Productivity, And Nitrogen Retention, John L. Maron, Robert L. Jefferies Aug 2001

Restoring Enriched Grasslands: Effects Of Mowing On Species Richness, Productivity, And Nitrogen Retention, John L. Maron, Robert L. Jefferies

Biological Sciences Faculty Publications

Species-rich grasslands that become enriched with nitrogen often suffer decreases in species richness, increases in plant biomass, and invasion by weedy exotic species. Suitable techniques to restore enriched grasslands and reestablish native communities are increasingly needed. Here we report results of a 5-yr experiment in enriched coastal prairie grasslands (Bodega Marine Reserve, Bodega Bay, California, USA), to determine the combined effects of mowing and biomass removal on total soil nitrogen, net rates of mineralization, nitrogen retention, and species richness and biomass. We mowed and removed plant biomass from plots in areas where the N-fixing shrub, bush lupine (Lupinus arboreus …

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Establishing A Direct Role For The Bartonella Bacilliformis Invasion-Associated Locus B (Ialb) Protein In Human Erythrocyte Parasitism, Sherry A. Coleman, Michael F. Minnick Jul 2001

Establishing A Direct Role For The Bartonella Bacilliformis Invasion-Associated Locus B (Ialb) Protein In Human Erythrocyte Parasitism, Sherry A. Coleman, Michael F. Minnick

Biological Sciences Faculty Publications

The invasion-associated locus A and B genes (ialAB) of Bartonella bacilliformis were previously shown to confer an erythrocyte-invasive phenotype upon Escherichia coli, indirectly implicating their role in virulence. We report the first direct demonstration of a role for ialB as a virulence factor in B, bacilliformis. The presence of a secretory signal sequence and amino acid sequence similarity to two known outer membrane proteins involved in virulence suggested that IalB was an outer membrane protein, To develop an antiserum for protein localization, the ialB gene was cloned in frame into an expression vector with a six-histidine tag and under control …

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Assembly Of Reca-Like Recombinases: Distinct Roles For Mediator Proteins In Mitosis And Meiosis, Stephen L. Gasior Jul 2001

Assembly Of Reca-Like Recombinases: Distinct Roles For Mediator Proteins In Mitosis And Meiosis, Stephen L. Gasior

Biological Sciences Faculty Publications

Members of the RecA family of recombinases from bacteriophage T4, Escherichia coli, yeast, and higher eukaryotes function in recombination as higher-order oligomers assembled on tracts of single-strand DNA (ssDNA). Biochemical studies have shown that assembly of recombinase involves accessory factors. These studies have identified a class of proteins, called recombination mediator proteins, that act by promoting assembly of recombinase on ssDNA tracts that are bound by ssDNA-binding protein (ssb). In the absence of mediators, ssb inhibits recombination reactions by competing with recombinase for DNA-binding sites. Here we briefly review mediated recombinase assembly and present results of new in vivo experiments. …

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C2 Domains From Different Ca2+ Signaling Pathways Display Functional And Mechanistic Diversity, E. A. Nalefski, M. A. Wisner, J. Z. Chen, S. R. Sprang, M. Fukuda, K. Mikoshiba, J. J. Falke Mar 2001

C2 Domains From Different Ca2+ Signaling Pathways Display Functional And Mechanistic Diversity, E. A. Nalefski, M. A. Wisner, J. Z. Chen, S. R. Sprang, M. Fukuda, K. Mikoshiba, J. J. Falke

Biological Sciences Faculty Publications

The ubiquitous C2 domain is a conserved Ca2+-triggered membrane-docking module that targets numerous signaling proteins to membrane surfaces where they regulate diverse processes critical for cell signaling. In this study, we quantitatively compared the equilibrium and kinetic parameters of C2 domains isolated from three functionally distinct signaling proteins: cytosolic phospholipase A2-α (cPLA2-α), protein kinase C-β (PKC-β), and synaptotagmin-IA (Syt-IA). The results show that equilibrium C2 domain docking to mixed phosphatidylcholine and phosphatidylserine membranes occurs at micromolar Ca2+ concentrations for the cPLA2-α C2 domain, but requires 3- and 10-fold higher Ca2+ …

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