Biology Commons^™

Molecular Evidence For A New Bacteriophage Of Borrelia Burgdorferi, Christian H. Eggers, D. Scott Samuels

Biological Sciences Faculty Publications

We have recovered a DNase-protected, chloroform-resistant molecule of DNA from the cell-free supernatant of a Borrelia burgdorferi culture. The DNA is a 32-kb double-stranded linear molecule that is derived from the 32-kb circular plasmids (cp32s) of the B. burgdorferi genome. Electron microscopy of samples from which the 32-kb DNA molecule was purified revealed bacteriophage particles. The bacteriophage has a polyhedral head with a diameter of 55 nm and appears to have a simple 100-nm-long tail. The phage is produced constitutively at low levels from growing cultures of some B. burgdorferi strains and is inducible to higher levels with 10 mu …

Three-Dimensional Structure Of A Complex Between The Death Domains Of Pelle And Tube, Tsan Xiao, Par Towb, Steven A. Wasserman, Stephen R. Sprang

Biological Sciences Faculty Publications

The interaction of the serine/threonine kinase Pelle and adaptor protein Tube through their N-terminal death domains leads to the nuclear translocation of the transcription factor Dorsal and activation of zygotic patterning genes during Drosophila embryogenesis. Crystal structure of the Pelle and Tube death domain heterodimer reveals that the two death domains adopt a six-helix bundle fold and are arranged in an open-ended linear array with plastic interfaces mediating their interactions. The Tube death domain has an insertion between helices 2 and 3, and a C-terminal tail making significant and indispensable contacts in the heterodimer. In vivo assays of Pelle and …

Systematic Changes In Gene Expression Patterns Following Adaptive Evolution In Yeast, Tracy L. Ferea, David Botstein, Patrick O. Brown, R. Frank Rosenzweig

Biological Sciences Faculty Publications

Culturing a population of Saccharomyces cerevisiae for many generations under conditions to which it is not optimally adapted selects for fitter genetic variants. This simple experimental design provides a tractable model of adaptive evolution under natural selection. Beginning with a clonal, founding population, independently evolved strains were obtained from three independent cultures after continuous aerobic growth in glucose-limited chemostats for more than 250 generations. DNA microarrays were used to compare genome-wide patterns of gene expression in the evolved strains and the parental strain. Several hundred genes were found to have significantly altered expression in the evolved strains. Many of these …

Using Atlas Data To Model The Distribution Of Woodpecker Species In The Jura, France, Claudine Tobalske, Bret W. Tobalske

Biological Sciences Faculty Publications

Breeding bird atlases providing distribution data at a regional scale are becoming increasingly common. To assess the ability of such data to develop bread-scale bird-habitat models, we used data from a breeding bird atlas and landscape variables obtained From a geographic information system (GIS) to study the distribution of seven woodpecker species in the Jura, France: the Black (Dryocopus martins), Green (Picus viridis). Grey-headed (P. canus), Great Spotted (Dendrocopos major), Middle Spotted (D. medius), and Lesser Spotted (D. minor) Woodpeckers, and the Wryneck (Jynx torquilla). We used logistic regression to develop predictive models from variables that described each 575-ha atlas …

Development Of A System For Genetic Manipulation Of Bartonella Bacilliformis, James M. Battisti, Michael F. Minnick

Biological Sciences Faculty Publications

Lack of a system for site specific genetic manipulation has severely hindered studies on the molecular biology of all Bartonella species. We report the first site-specific mutagenesis and complementation for a Bartonella species. A highly transformable strain of B. bacilliformis, termed JB584, was isolated and found to exhibit a significant increase in transformation efficiency with the broad-host-range plasmid pBBR1MCS-2, relative to wild-type strains. Restriction analyses of genomic preparations with the methylation-sensitive restriction enzymes ClaI and StuI suggest that strain JB584 possesses a dcm methylase mutation that contributes to its enhanced transformability. A suicide plasmid, pUB1, which contains a polylinker, a …

Two-Metal-Ion Catalysis In Adenylyl Cyclase, John J.G. Tesmer, Roger K. Sunahara, Roger A. Johnson, Gilles Gosselin, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

Adenylyl cyclase (AC) converts adenosine triphosphate (ATP) to cyclic adenosine monophosphate, a ubiquitous second messenger that regulates many cellular functions. Recent structural studies have revealed much about the structure and function of mammalian AC but have not fully defined its active site or catalytic mechanism. Four crystal structures were determined of the catalytic domains of AC in complex with two different ATP analogs and various divalent metal ions. These structures provide a model for the enzyme- substrate complex and conclusively demonstrate that two metal ions bind in the active site. The similarity of the active site of AC to those …

Positions In The 30s Ribosomal Subunit Proximal To The 790 Loop As Determined By Phenanthroline Cleavage, Gregory W. Muth, Scott P. Hennelly, Walter E. Hill

Biological Sciences Faculty Publications

Positioning rRNA within the ribosome remains a challenging problem. Such positioning is critical to understanding ribosome function, as various rRNA regions interact to form suitable binding sites for ligands, such as tRNA and mRNA. We have used phenanthroline, a chemical nuclease, as a proximity probe, to help elucidate the regions of rRNA that are near neighbors of the stem-loop structure centering at nt 790 in the 16S rRNA of the Escherichia coli 30S ribosomal subunit. Using phenanthroline covalently attached to a DNA oligomer complementary to nt 787-795, we found that nt 582-584, 693-694, 787-790, and 795-797 were cleaved robustly and …

Structure Of G(Iα1)·Gppnhp, Autoinhibition In A Gα Protein-Substrate Complex, David E. Coleman, Stephen R. Sprang

Biological Sciences Faculty Publications

The structure of the G protein G(i 1/4 ) complexed with the nonhydrolyzable GTP analog guanosine-5'-(βγ-imino)triphosphate (GppNHp) has been determined at a resolution of 1.5 Å. In the active site of G(i 1/4 )·GppNHp, a water molecule is hydrogen bonded to the side chain of Glu⁴³ and to an oxygen atom of the γ-phosphate group. The side chain of the essential catalytic residue Gln²⁰⁴ assumes a conformation which is distinctly different from that observed in complexes with either guanosine 5'-O-3-thiotriphosphate or the transition state analog GDP·A1F₄^-. Hydrogen bonding and steric interactions position Gln²⁰⁴ such …

Biological-Control Herbivores May Increase Competitive Ability Of The Noxious Weed Centaurea Maculosa, Ragan M. Callaway, Thomas H. Deluca, Wendy M. Belliveau

Biological Sciences Faculty Publications

Biocontrol organisms are generally applied in an attempt to reduce the vigor of target species and provide native species with an competitive advantage. We tested the effectiveness of a widely used biocontrol moth, Agapeta zoegana (knapweed root moth) for two years in the field and found that it had no significant direct effect on the biomass of Centaurea maculosa (spotted knapweed), one of the most destructive invasive plants in North America. Instead of releasing a native grass from competition, the reproductive output of Festuca idahoensis planted with Centaurea was significantly lower when neighboring Centaurea had been attacked by Agapeta. In …

Mycorrhizae Indirectly Enhance Competitive Effects Of An Invasive Forb On A Native Bunchgrass, Marilyn J. Marler, Catherine A. Zabinski, Ragan M. Callaway

Biological Sciences Faculty Publications

Mycorrhizae are important mediators of plant competition, but little is known about the role of mycorrhizae in the intense competitive effects that exotic plants can have on native species. In the greenhouse, we tested the effect of arbuscular mycorrhizal (AM) fungi on interspecific competition between Centaurea maculosa and Festuca idahoensis, on intraspecific competition between individuals of both species, and the growth of C. maculosa with either inorganic or organic phosphorus. Mycorrhizae had no direct effect on either species, but mycorrhizae increased C. maculosa's negative effect on F. idahoensis. When competing with C. maculosa, nonmycorrhizal F. idahoensis were 171% larger than …

Cleavage Of A 23s Rrna Pseudoknot By Phenanthroline-Cu(Ii), G. W. Muth, Charles M. Thompson, Walter E. Hill

Biological Sciences Faculty Publications

Studying the intricate folding of rRNA within the ribosome remains a complex problem. Phenanthroline-Cu(II) complexes cleave phosphodiester bonds in rRNA in specific regions, apparently especially where the rRNA structure is constrained in some fashion. We have introduced phenanthroline-copper complexes into 50S Escherichia coli ribosomal subunits and shown specific cleavages in the regions containing nucleotides 60-66 and 87-100. This specificity of cleavage is reduced when the ribosome is heated to 80 degrees C and reduced to background when the ribosomal proteins are extracted and the cleavage repeated on protein-free 23S rRNA, It has been suggested that nucleotides 60-66 and 87-95 in …

Nmr Solution Structure Of Plastocyanin From The Photosynthetic Prokaryote, Prochlorothrix Hollandica, Charles R. Babu, Brian F. Volkman, George S. Bullerjahn

Biological Sciences Faculty Publications

The solution structure of a divergent plastocyanin (PC) from the photosynthetic prokaryote Prochlorothrix hollandica was determined by homonuclear H-1 NMR spectroscopy. Nineteen structures were calculated from 1222 distance restraints, yielding a family of structures having an average rmsd of 0.42 +/- 0.08 Angstrom, for backbone atoms and 0.71 +/- 0.07 Angstrom for heavy atoms to the mean structure. No distance constraint was violated by more than 0.26 Angstrom in the structure family. Despite the low number of conserved residues shared with other PC homologues, the overall folding pattern of P. hollandica PC is similar to other PCs, in that the …

Toward An Evolutionary Understanding Of Song Diversity In Oscines, Erick Greene

Biological Sciences Faculty Publications

No abstract provided.

Bush Lupine Mortality, Altered Resource Availability, And Alternative Vegetaion States, John L. Maron, Robert L. Jefferies

Biological Sciences Faculty Publications

Nitrogen-fixing plants, by altering the availability of soil N, potentially facilitate plant invasion. Here we describe how herbivore-driven mortality of a native N-fixing shrub, bush lupine (Lupinus arboreus), increases soil N and light availability, which promotes invasion by introduced grasses to the detriment of a native plant community.

Soils under live and dead lupine stands contained large amounts of total N, averaging 3.14 mg N/g dry mass of soil (398 g/m²) and 3.45 mg N/g dry mass of soil (438 g/m²), respectively, over four years. In contrast, similar lupine-free soil was low in N …

Exploring Cost Constraints On Stem Elongation In Plants Using Phenotypic Manipulation, Don Cipollini, Jack C. Schultz

Biological Sciences Faculty Publications

Negative associations between individual life‐history traits of an organism are referred to as life‐history trade‐offs (Stearns 1992; Zera et al. 1998). The existence of costly trade‐offs is thought to have favored the evolution of phenotypic plasticity as a mechanism through which organisms can account for environmental heterogeneity while modulating costs and benefits incurred by fixed allocation to competing functions (Bradshaw 1965; Stearns 1992; Sultan 1995; Dudley and Schmitt 1996; Pigliucci 1996). In plants, the ability to modify stem elongation in response to environmental cues appears to be a classic form of adaptive phenotypic plasticity (Sultan 1995; Gedroc et al. 1996). …

Role Of Iron, Light, And Silicate In Controlling Algal Biomass In Subantarctic Waters Se Of New Zealand, Robert Michael Mckay, Philip Boyd, Julie Laroche, Mark Gall, Russell Frew

Biological Sciences Faculty Publications

Phytoplankton processes in subantarctic (SA) waters southeast of New Zealand were studied during austral autumn and spring 1997. Chlorophyll a (0.2–0.3 μg L⁻¹) and primary production (350–650 mg C m⁻² d⁻¹) were dominated by cells μm (cyanobacteria) in both seasons. The photochemical efficiency of photosystem II (F_υ/F_m) of cells was low (0.3), indicating physiological stress. Dissolved Fe (DFe) levels in surface waters were subnanomolar, and the molecular marker flavodoxin indicated that cells were iron stressed. In contrast, Subtropical Convergence (STC) and subtropical waters had higher algal biomass/production levels, particularly …

Pfiesteria Piscicida And Dinoflagellates Similar To Pfiesteria, Harold G. Marshall

Biological Sciences Faculty Publications

Pfiesteria pisiccida is a microscopic, unicellular organism that is classified as both a mixotrophic and heterotrophic dinoflagellate, which has been associated with both fish deaths and a cause of human illness (Burkholder et al., 1992; Glasglow et al., 1995; Burkholder and Glasgow, 1997). This species possesses a complex life cycle that includes motile forms (e.g. zoospores, gametes, amoebae) and a cyst stage that may remain dormant in the sediment (Burkholder et al, 1995b). Pfiesteria piscicida is known to have toxin and non-toxin producing populations, where cyst transformation into the toxic motile zoospores may be initiated by the presence of certain …

Habitat Relationships Of Landbirds In The Northern Region, Usda Forest Service, Richard L. Hutto, Jock S. Young

Biological Sciences Faculty Publications

A series of first-generation habitat-relationships models for 83 bird species were detected in a 3-year study on point counts conducted in association with the USDA Forest Service's Northern Region Landbird Monitoring Program. The models depict probabilities of detection for each of the bird species on 100-m-radius, 10-minute point counts conducted across a series of major vegetation cover types. Based on these models, some bird species appear to be restricted in their habitat distribution to: (1) postfire, standing-dead forests, (2) relatively uncut, older forests, (3) harvested forest types, (4) marshes, (5) riparian environments, and (6) grasslands and sagebrush. Such restricted distributions …

Monitoring Results For Pfiesteria Piscidida And Pfiesteria-Like Organisms From Virginia Waters In 1998, Harold G. Marshall, David W. Seaborn, Jennifer Wolny

Biological Sciences Faculty Publications

Results of an extensive 1998 monitoring program for the presence of Pfiesteria-like organisms (PLO) in Virginia estuaries indicate these dinoflagellates are widely distributed in both the water column, and as cysts in the sediment, however Pfiesteria piscicida was not detected at this time. The highest concentrations of PLO were in estuaries along the Virginia shore line of the Potomac River, and in western Chesapeake Bay estuaries from the Little Wicomico River to the Rappahannock River. The most common PLO included Cryptoperidiniopsis sp. and Gymnodinium galatheanum. The lowest PLO concentrations were at ocean side locations. PLO were also …