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Biological Sciences Faculty Publications

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Articles 1411 - 1440 of 1571

Full-Text Articles in Life Sciences

Seeing Double: Crystal Structures Of The Type I Tnf Receptor, James H. Naismith, Barbara J. Brandhuber, Tracey Q. Devine, Stephen R. Sprang Jan 1996

Seeing Double: Crystal Structures Of The Type I Tnf Receptor, James H. Naismith, Barbara J. Brandhuber, Tracey Q. Devine, Stephen R. Sprang

Biological Sciences Faculty Publications

The crystal structure of the extracellular domain of the type I tumor necrosis factor receptor (sTNF-R1) has been determined to 2.25 Å at pH 7.5. We have also solved the structure of sTNF-R1 at pH 3.7. sTNF-R1 is an elongated molecule consisting of a linear combination of four cysteine-rich motifs. Interestingly, the crystal structure reveals two distinct dimers of the receptor. One dimer is formed by a parallel arrangement of receptors, the other by an antiparallel arrangement of receptors. In the parallel arrangement of the receptors, the tumor necrosis factor (TNF) binding face of the receptor is completely exposed to …

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Scaling Of Muscle Composition, Wing Morphology, And Intermittent Flight Behavior In Woodpeckers, Bret W. Tobalske Jan 1996

Scaling Of Muscle Composition, Wing Morphology, And Intermittent Flight Behavior In Woodpeckers, Bret W. Tobalske

Biological Sciences Faculty Publications

Existing theory and empirical evidence suggest that body size should have a profound influence upon the composition of flight muscles and the performance of intermittent flight in birds. I examine the relationships between functional morphology and intermittent flight behavior within a closely-related group of birds using six species of woodpeckers (Picidae): Downy Woodpecker (Picoides pubescens, 27.2 g), Red-naped Sapsucker (Sphyrapicus nuchalis, 47.4 g), Hairy Woodpecker (P. villosus, 70.5 g), Lewis' Woodpecker (Melanerpes lewis, 106.6 g), Northern Flicker (Colaptes auratus, 148.1 g), and Pileated Woodpecker (Dryocopus pileatus, 262.5 g). In woodpeckers with a body mass less than 100 g, the pectoralis …

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Top-Down Cascade From A Bitrophic Predator In An Old-Field Community, Matthew D. Moran, Thomas P. Rooney, L. E. Hurd Jan 1996

Top-Down Cascade From A Bitrophic Predator In An Old-Field Community, Matthew D. Moran, Thomas P. Rooney, L. E. Hurd

Biological Sciences Faculty Publications

We tested the hypothesis that a bitrophic (third and fourth level) arthropod predator can exert a cascading, top-down influence on other arthropods and plants in an early successional old field. First-stadium mantids, Tenodera sinensis, were added to replicated open-field plots in numbers corresponding to naturally occurring egg hatch density and allowed to remain for ≈ 2 mo. Sticky-trap dispersal barriers around both control and mantid-addition plots allowed us to monitor emigration of arthropods continuously during the experiment. Biomass of herbivores, carnivores, and plants, and abundances of arthropod taxa within plots were determined at the beginning, middle, and end of …

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Toxin Producing Phytoplankton In Chesapeake Bay, Harold G. Marshall Jan 1996

Toxin Producing Phytoplankton In Chesapeake Bay, Harold G. Marshall

Biological Sciences Faculty Publications

Three diatoms and nine dinoflagellates, known to be associated with toxin production, have been identified within Chesapeake Bay. Over the past several decades this number has increased to its present level so that they now represent approximately 1.7% the total number of phytoplankton species reported for the Bay.

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Effects Of Regional Origin And Genotype On Intraspecific Root Communication In The Desert Shrub Ambrosia Dumosa (Asteraceae), Bruce E. Mahall, Ragan M. Callaway Jan 1996

Effects Of Regional Origin And Genotype On Intraspecific Root Communication In The Desert Shrub Ambrosia Dumosa (Asteraceae), Bruce E. Mahall, Ragan M. Callaway

Biological Sciences Faculty Publications

Previous work has shown that the contact inhibition that occurs among roots of Ambrosia dumosa shrubs has a self/nonself recognition capability. In the current study, we investigated some of the geographic and genotypic dimensions of this recognition capability by using root observation chambers to observe the effects of encounters of individual roots on root elongation rates. We measured such effects in encounters between roots of plants from the same region and compared these to effects in encounters between roots of plants from two different regions. We also measured effects of encounters between roots of plants from the same clones and …

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Variation In Leaf Structure And Function In Quercus Douglasii Trees Differing In Root Architecture And Drought History, Ragan M. Callaway, Bruce E. Mahall Jan 1996

Variation In Leaf Structure And Function In Quercus Douglasii Trees Differing In Root Architecture And Drought History, Ragan M. Callaway, Bruce E. Mahall

Biological Sciences Faculty Publications

Seasonal changes in leaf specific mass, nitrogen, chlorophyll, and photosynthetic properties were measured for two groups of spatially intermixed Quercus douglasii trees with different drought histories and apparently different root architectures. One group, referred to as ''high-psi(pd) trees, included trees with low amounts of fine root biomass in the upper 50 cm of soil and high predawn xylem pressure potentials (psi(pd)) during summer drought. These two characteristics indicate that trees in this group have deep roots, which may reach the water table. The second group, referred to as ''low-psi(pd) trees, had three to five times higher fine root biomass in …

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The Structure Of The G Protein Heterotrimer GIα1Β1Γ2, Mark A. Wall, David E. Coleman, Ethan Lee, Jorge A. Iñiguez-Lluhi, Bruce A. Posner, Alfred G. Gilman, Stephen R. Sprang Dec 1995

The Structure Of The G Protein Heterotrimer GIα1Β1Γ2, Mark A. Wall, David E. Coleman, Ethan Lee, Jorge A. Iñiguez-Lluhi, Bruce A. Posner, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

The crystallographic structure of the G protein heterotrimer Giα1(GDP)β1γ2 (at 2.3 A) reveals two nonoverlapping regions of contact between α and β, an extended interface between β and nearly all of γ, and limited interaction of α with γ. The major α/β interface covers switch II of α, and GTP-induced rearrangement of switch II causes subunit dissociation during signaling. Alterations in GDP binding in the heterotrimer (compared with α-GDP) explain stabilization of the inactive conformation of α by βγ. Repeated WD motifs in β form a circularized sevenfold β propeller. The conserved cores of these …

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Cascading Disturbances In Florida Bay, Usa: Cyanobacteria Blooms, Sponge Mortality, And Implications For Juvenile Spiny Lobsters Panulirus Argus, Mark J. Butler Iv, John H. Hunt, William F. Herrnkind, Michael J. Childress, Rodney Bertelsen, William Sharp, Thomas Matthews, Jennifer M. Field, Harold G. Marshall Dec 1995

Cascading Disturbances In Florida Bay, Usa: Cyanobacteria Blooms, Sponge Mortality, And Implications For Juvenile Spiny Lobsters Panulirus Argus, Mark J. Butler Iv, John H. Hunt, William F. Herrnkind, Michael J. Childress, Rodney Bertelsen, William Sharp, Thomas Matthews, Jennifer M. Field, Harold G. Marshall

Biological Sciences Faculty Publications

Florida Bay, the shallow lagoon separating mainland Florida and the Florida Keys, USA, is experiencing an unprecedented series of ecological disturbances. In 1991, following reports of other ecosystem perturbations, we observed widespread and persistent blooms of cyanobacteria that coincided with the decimation of sponge communities over hundreds of square kilometers. Juvenile Caribbean spiny lobsters Panulirus argus, among other animals, rely on sponges for shelter; the impact of sponge loss on the abundance of lobsters and their use of shelter, in particular, has been dramatic. The loss of sponges on 27 experimental sites in hard bottom habitat in central Florida Bay …

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2,4-Dichlorophenoxyacetic Acid-Degrading Bacteria Contain Mosaics Of Catabolic Genes, R. R. Fulthorpe, C. Mcgowan, O. V. Maltseva, William E. Holben, J. M. Tiedje Sep 1995

2,4-Dichlorophenoxyacetic Acid-Degrading Bacteria Contain Mosaics Of Catabolic Genes, R. R. Fulthorpe, C. Mcgowan, O. V. Maltseva, William E. Holben, J. M. Tiedje

Biological Sciences Faculty Publications

DNA from 32 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria from diverse locations was probed with the first three genes of the well-known 2,4-D degradation pathway found in Alcaligenes eutrophus JMP134(pJP4). The majority of strains did not show high levels of homology to the first three genes of the 2,4-D degradation pathway, tfdA, -B, and -C. Most strains showed combinations of tfdA-, B-, and C-like elements that exhibited various degrees of homology to the gene probes. Strains having the same genomic fingerprints (as determined by repetitive extragenic palindromic PCR) exhibited the same hybridization pattern regardless of the geographic origin of the …

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How Ras Works: Structure Of A Rap-Raf Complex, Stephen R. Sprang Jul 1995

How Ras Works: Structure Of A Rap-Raf Complex, Stephen R. Sprang

Biological Sciences Faculty Publications

The three-dimensional structure of the complex between Rap and the 'Ras-binding domain' of Raf could be the prototype for a G protein-effector interaction.

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Crystallographic Evidence For Dimerization Of Unliganded Tumor Necrosis Factor Receptor, James H. Naismith, Tracey Q. Devine, Barbara J. Brandhuber, Stephen R. Sprang Jun 1995

Crystallographic Evidence For Dimerization Of Unliganded Tumor Necrosis Factor Receptor, James H. Naismith, Tracey Q. Devine, Barbara J. Brandhuber, Stephen R. Sprang

Biological Sciences Faculty Publications

Activation of the cell surface receptors for tumor necrosis factor (TNF) is effected by the aggregation of cytoplasmic domains that occurs when the extracellular domains of two or three receptors bind to trimeric TNFα or TNFβ. The structure of the type I TNF receptor extracellular domain (sTNF- R1), crystallized in the absence of TNF, has now been determined at 2.25-Å resolution. The receptor itself is an elongated molecule comprising four disulfide-rich domains in a nearly linear array. Contrary to expectations, the unliganded domains are found to associate into dimers of two distinct types, in which monomers are related by local …

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Effects Of Reproductive Mode On Demography And Life History In Arabis Fecunda (Brassicaceae), Peter Lesica, J. Stephen Shelly Jun 1995

Effects Of Reproductive Mode On Demography And Life History In Arabis Fecunda (Brassicaceae), Peter Lesica, J. Stephen Shelly

Biological Sciences Faculty Publications

Life history theory predicts that trade-offs between growth and reproduction should be dictated by a population's mortality schedule. We tested this prediction with Arabis fecunda, a short-lived perennial that occurs in many different habitats in southwest Montana. Individuals produce either or both axillary or terminal inflorescences. Axillary-flowering plants are usually iteroparous and have smaller reproductive bouts, while terminal-flowering plants have larger reproductive bouts, and tend to be semelparous. We recorded size and fecundity of A. fecunda individuals from 1989 to 1993 in three different habitats. There was great variation in demographic and life history traits among the populations. A …

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Characterization Of Diverse 2,4-Dichlorophenoxyacetic Acid-Degradative Plasmids Isolated From Soil By Complementation, Eva M. Top, William E. Holben, Larry J. Forney May 1995

Characterization Of Diverse 2,4-Dichlorophenoxyacetic Acid-Degradative Plasmids Isolated From Soil By Complementation, Eva M. Top, William E. Holben, Larry J. Forney

Biological Sciences Faculty Publications

The diversity of 2,4-dichlorophenoxyacetic acid (2,4-D)-degradative plasmids in the microbial community of an agricultural soil was examined by complementation. This technique involved mixing a suitable Alcaligenes eutrophus (Rifr) recipient strain with the indigenous microbial populations extracted from soil. After incubation of this mixture, Rifr recipient strains which grow with 2,4-D as the only C source were selected. Two A. eutrophus strains were used as recipients: JMP228 (2,4-D-), which was previously derived from A. eutrophus JMP134 by curing of the 2,4-D-degradative plasmid pJP4, and JMP228 carrying pBH501aE (a plasmid derived from pJP4 by deletion of a …

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Maintaining Bird Diversity In Western Larch/Douglas-Fir Forests, Bret W. Tobalske, Raymond C. Shearer, Richard L. Hutto May 1995

Maintaining Bird Diversity In Western Larch/Douglas-Fir Forests, Bret W. Tobalske, Raymond C. Shearer, Richard L. Hutto

Biological Sciences Faculty Publications

Bird occurrences were evaluated under four stand conditions in western larch/Douglas-fir forests: clearcut, partial cut, unlogged (fragmented), and contiguous forest. Frequencies were noted for foraging guilds, tree gleaners, flycatchers, nesting guilds, tree drillers, and primary cavity nesters. Managers should consider a diversity of habitat conditions if maintaining habitat for bird species is an objective.

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Structure Of The First C2 Domain Of Synaptotagmin I: A Novel Ca(2+)/Phospholipid-Binding Fold, R. Bryan Sutton, Bazbek A. Davletov, Albert M. Berghuis, Thomas C. Sudhof, Stephen R. Sprang Mar 1995

Structure Of The First C2 Domain Of Synaptotagmin I: A Novel Ca(2+)/Phospholipid-Binding Fold, R. Bryan Sutton, Bazbek A. Davletov, Albert M. Berghuis, Thomas C. Sudhof, Stephen R. Sprang

Biological Sciences Faculty Publications

C2 domains are regulatory sequence motifs that occur widely in nature. Synaptotagmin I, a synaptic vesicle protein involved in the Ca2+ regulation of exocytosis, contains two C2 domains, the first of which acts as a Ca2+ sensor. We now describe the three-dimensional structure of this C2 domain at 1.9 Å resolution in both the Ca2+-bound and Ca2+-free forms. The C2 polypeptide forms an eight-stranded β sandwich constructed around a conserved four-stranded motif designated as a C2 key. Ca2+ binds in a cup-shaped depression between two polypeptide loops located …

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Effects Of Silvicultural Treatments In The Rocky Mountains, Sallie J. Hejl, Richard L. Hutto, Charles R. Preston, Deborah M. Finch Jan 1995

Effects Of Silvicultural Treatments In The Rocky Mountains, Sallie J. Hejl, Richard L. Hutto, Charles R. Preston, Deborah M. Finch

Biological Sciences Faculty Publications

We offer a description of current forest structure and basic information on bird distribution across forest habitats in the Rockies as background knowledge for understanding the effects of silviculture on birds in these habitats. We also offer a comparison between the effects of silviculture, and the effects of fire and fire suppression on forest birds in an attempt to give a holistic perspective on the health of forest birds' in the Rockies.

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A Comparison Of Bird Detection Rates Derived From On-Road Versus Off-Road Point Counts In Northern Montana, Richard L. Hutto, Sallie J. Hejl, Jeffrey F. Kelly, Sandra M. Pletschet Jan 1995

A Comparison Of Bird Detection Rates Derived From On-Road Versus Off-Road Point Counts In Northern Montana, Richard L. Hutto, Sallie J. Hejl, Jeffrey F. Kelly, Sandra M. Pletschet

Biological Sciences Faculty Publications

We conducted a series of 275 paired (on- and off-road) point counts within 4 distinct vegetation cover types in northwestern Montana. Roadside counts generated a bird list that was essentially the same as the list generated from off-road counts within the same vegetation cover type. Species that were restricted to either on- or off-road counts were rare, suggesting that restricted occurrences were a consequence of small sample sizes and not a product of habitat differences surrounding on-versus off-road points. Nevertheless, there were significant differences in the mean number of individuals detected between on- and off-road points for a number of …

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Unstable And Stable Classifications Of Scombroid Fishes, Kent E. Carpenter, Bruce B. Collette, Joseph L. Russo Jan 1995

Unstable And Stable Classifications Of Scombroid Fishes, Kent E. Carpenter, Bruce B. Collette, Joseph L. Russo

Biological Sciences Faculty Publications

Many cladists believe that a classification should strictly reflect a cladistic hypothesis. Consequently, they propose classifications that often differ markedly from existing ones and are potentially unstable due to phylogenetic uncertainty. This is problematic for economically or ecologically important organisms since changing classifications can cause confusion in their management as resources. The classification of the 44 genera of scombroid fishes (the mackerels, tunas, billfishes, and their relatives) illustrates this problem of instability. Previous cladistic analyses and analyses presented in this paper, using different data sets, result in many different cladistic hypotheses. In addition, the inferred cladograms are unstable because of …

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Response By Reticulitermes (Isoptera: Rhinotermitidae) And Cryptocercus Punctulatus (Blattaria: Cryptocercidae) To Wood Infected With The Green-Stain Ascomycete, Chlorociboria Aeruginascens Aeruginascens, Deborah Waller Jan 1995

Response By Reticulitermes (Isoptera: Rhinotermitidae) And Cryptocercus Punctulatus (Blattaria: Cryptocercidae) To Wood Infected With The Green-Stain Ascomycete, Chlorociboria Aeruginascens Aeruginascens, Deborah Waller

Biological Sciences Faculty Publications

Termites of the genus Reticulitermes Holmgren and the wood roaches Cryptocercus punctulatus Scutter were observed feeding on wood stained green by the ascomycete fungus, Chlorociboria aeruginascens aeruginascens (Leotiaceae), in a Virginia forest. However, in laboratory choice trials, both termites and wood roaches preferred unstained wood to stained wood. In no-choice feeding trials, Reticulitermes fed stained birch ate significantly less wood and weighed significantly less than termites fed unstained birch. These results indicate that natural host utilization patterns cannot be relied upon to indicate feeding preferences.

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Scleractinian Corals Of Kuwait, G. Hodgson, Kent E. Carpenter Jan 1995

Scleractinian Corals Of Kuwait, G. Hodgson, Kent E. Carpenter

Biological Sciences Faculty Publications

A survey was made of the coral reefs of Kuwait to compile a species list of scleractinian corals. Twenty-eight hermatypic and six ahermatypic coral species are listed in systematic order, and a brief description is provided for each. A new species of Acropora is described. The Kuwait fauna is a small subset of the over 500 Indo-Pacific species. Several species show a higher degree of intraspecific variation than they exhibit in other locations. A range extension is reported for Acanthastrea maxima Sheppard & Salm, previously recorded from Oman (north and south coasts). A common species in the Arabian Gulf, Porites …

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Genetic Transformation Of The Lyme Disease Agent Borrelia Burgdorferi With Coumarin-Resistant Gyrb., D. Scott Samuels, Kathleen E. Mach, Claude F. Garon Oct 1994

Genetic Transformation Of The Lyme Disease Agent Borrelia Burgdorferi With Coumarin-Resistant Gyrb., D. Scott Samuels, Kathleen E. Mach, Claude F. Garon

Biological Sciences Faculty Publications

No useful method to genetically manipulate Borrelia burgdorferi, the causative agent of Lyme disease, has been developed previously. We have used resistance to the coumarin antibiotic coumermycin A1, an inhibitor of DNA gyrase, as a genetic marker to monitor the transformation of B. burgdorferi by electroporation. Introduction of site-directed mutations into the gyrB gene demonstrated that transformation was successful, provided evidence that homologous recombination occurs on the chromosome, and established that mutations at Arg-133 of DNA gyrase B confer coumermycin A1 resistance in B. burgdorferi. The coumermycin A1-resistant gyrB marker and genetic transformation can now be applied toward dissecting the …

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Mechanism Of Gtp Hydrolysis By G-Protein Α Subunits, Christiane Kleuss, André S. Raw, Ethan Lee, Stephen R. Sprang, Alfred G. Gilman Oct 1994

Mechanism Of Gtp Hydrolysis By G-Protein Α Subunits, Christiane Kleuss, André S. Raw, Ethan Lee, Stephen R. Sprang, Alfred G. Gilman

Biological Sciences Faculty Publications

Hydrolysis of GTP by a variety of guanine nucleotide-binding proteins is a crucial step for regulation of these biological switches. Mutations that impair the GTPase activity of certain heterotrimeric signal-transducing G proteins or of p21(ras) cause tumors in man. A conserved glutamic residue in the α subunit of G proteins has been hypothesized to serve as a general base, thereby activating a water molecule for nucleophilic attack on GTP. The results of mutagenesis of this residue (Glu-207) in G(iα1) refute this hypothesis. Based on the structure of the complex of G(iα1) with GDP, Mg2+, and AlF4/ …

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Instructions For Building Two Live Traps For Small Mammals, Robert K. Rose Oct 1994

Instructions For Building Two Live Traps For Small Mammals, Robert K. Rose

Biological Sciences Faculty Publications

The two live traps described herein, tested in the field over a period of 10 years, are sturdy, long-lasting, and relatively inexpensive to build with readily available materials and simple tools.

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Benthic-Pelagic Links: Responses Of Benthos To Water-Column Nutrient Enrichment, S. C. Blumenshine, Yvonne Vadeboncoeur, D. M. Lodge, K. L. Cottingham, S. E. Knight Sep 1994

Benthic-Pelagic Links: Responses Of Benthos To Water-Column Nutrient Enrichment, S. C. Blumenshine, Yvonne Vadeboncoeur, D. M. Lodge, K. L. Cottingham, S. E. Knight

Biological Sciences Faculty Publications

Although the responses of pelagic algae and invertebrates to gradients of nutrient enrichment are well known, less is known about the responses of benthos to such gradients or how benthic and pelagic responses may interact. We performed a 9-wk experiment in 2000-L mesocosms in the field to test for the effect of water-column nutrient enrichment on phytoplankton, algae on sediments (epipelon) and hard surfaces (plastic strips), as well as pelagic and benthic primary consumers. The experimental design consisted of 4 nutrient enrichment rates (0, 0.5, 1.0 and 2.0 μg P L-1 d-1, together with N to yield …

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Analysis Of The Distribution And Molecular Heterogeneity Of The Ospd Gene Among The Lyme Disease Spirochetes: Evidence For Lateral Gene Exchange, Richard T. Marconi, D. Scott Samuels, Robert K. Landry, Claude F. Garon Aug 1994

Analysis Of The Distribution And Molecular Heterogeneity Of The Ospd Gene Among The Lyme Disease Spirochetes: Evidence For Lateral Gene Exchange, Richard T. Marconi, D. Scott Samuels, Robert K. Landry, Claude F. Garon

Biological Sciences Faculty Publications

Analysis of the ospD gene has revealed that this gene is not universal among Lyme disease spirochete isolates. The gene was found to be carried by 90, 50, and 24% of the Borrelia garinii, B. afzelii, and B. burgdorferi isolates tested. Size variability in the ospD-encoding plasmid was also observed. Sequence analysis has demonstrated the presence of various numbers of a 17-bp repeated sequence in the upstream control (promoter) region of the gene. In addition, a region within the coding sequence where various insertions, deletions, and direct repeats occur was identified. ospD gene sequences from 31 different isolates were determined …

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Identification Of Outer-Membrane Proteins Of Bartonella-Bacilliformis, Michael F. Minnick Jun 1994

Identification Of Outer-Membrane Proteins Of Bartonella-Bacilliformis, Michael F. Minnick

Biological Sciences Faculty Publications

Purification of the outer membrane of Bartonella bacilliformis by sucrose step gradient centrifugation and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) suggest that 14 proteins, ranging from 11.2 to 75.3 kDa, are located in the outer membrane of the pathogen. On the basis of M(r)s, eleven of these proteins have counterparts which are labeled by extrinsic radioiodination of intact bartonellae, and two of the proteins are visibly sensitive to extrinsic proteinase IC digestion in analysis by SDS-PAGE. While nearly all the extrinsically radioiodinated proteins could be immunoprecipitated with rabbit antibartonella hyperimmune serum, proteins of 31.5, 42, and 45 kDa …

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Longitudinal Dynamics Of Seston Concentration And Composition In A Lake Outlet Stream, Yvonne Vadeboncoeur Jun 1994

Longitudinal Dynamics Of Seston Concentration And Composition In A Lake Outlet Stream, Yvonne Vadeboncoeur

Biological Sciences Faculty Publications

Concentrations of suspended particulate organic carbon (POC), dissolved organic carbon, bacteria, and chlorophyll a were measured in a lake outlet in western Montana, USA. Seven sites within the first 3 km downstream from the lake were sampled over 14 mo. Downstream change in concentration of each variable was tested for fit to a power function (C=aDb). Downstream changes in POC, bacteria, and chlorophyll a, sometimes fit a power function, and the value of the exponent b was positively correlated with discharge. At low discharge, a downstream decline in lake algae was accompanied by an increase in stream algae. …

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Gyrb Mutations In Coumermycin A1-Resistant Borrelia Burgdorferi., D. Scott Samuels, Richard T. Marconi, Wai Mun Huang, Claude F. Garon May 1994

Gyrb Mutations In Coumermycin A1-Resistant Borrelia Burgdorferi., D. Scott Samuels, Richard T. Marconi, Wai Mun Huang, Claude F. Garon

Biological Sciences Faculty Publications

We have isolated and characterized mutants of Borrelia burgdorferi that are resistant to the antibiotic coumermycin A1, which targets the B subunit of DNA gyrase. Mutants had either 100- or 300-fold higher resistance to coumermycin A1 than wild-type B. burgdorferi. In each case, a single point mutation in the gyrB gene converted Arg-133 to Gly or Ile. Mutations in the homologous Arg residue of Escherichia coli DNA gyrase are also associated with resistance to coumarin antimicrobial agents.

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Use Of Gene Probes To Aid In Recovery And Identification Of Functionally Dominant 2,4-Dichlorophenoxyacetic Acid-Degrading Populations In Soil, J. O. Ka, William E. Holben, James M. Tiedje Apr 1994

Use Of Gene Probes To Aid In Recovery And Identification Of Functionally Dominant 2,4-Dichlorophenoxyacetic Acid-Degrading Populations In Soil, J. O. Ka, William E. Holben, James M. Tiedje

Biological Sciences Faculty Publications

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was applied to soils in microcosms, and degradation was monitored after each of five repeated additions. Total DNAs were isolated from soil bacterial communities after each 2,4-D treatment. The DNA samples were analyzed on slot blots and Southern blots by using a tfdA gene probe subcloned from plasmid pJP4 and a Spa probe derived from a different 2,4-D-degrading isolate, a Sphingomonas paucimobilis strain. 2,4-D applied to soil was quickly degraded by indigenous microbial populations. As determined by slot blot analyses of DNA from a Michigan soil, the increase in hybridization signal in response to 2,4-D …

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Analysis Of Competition In Soil Among 2,4-Dichlorophenoxyacetic Acid-Degrading Bacteria, J. O. Ka, William E. Holben, James M. Tiedje Apr 1994

Analysis Of Competition In Soil Among 2,4-Dichlorophenoxyacetic Acid-Degrading Bacteria, J. O. Ka, William E. Holben, James M. Tiedje

Biological Sciences Faculty Publications

Competition among indigenous and inoculated 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria was studied in a native Kansas prairie soil following 2,4-D additions. The soil was inoculated with four different 2,4-D-degrading strains at densities of 10(3) cells per g of soil; the organisms used were Pseudomonas cepacia DBO1(pJP4) and three Michigan soil isolates, strain 745, Sphingomonas paucimobilis 1443, and Pseudomonas pickettii 712. Following 2,4-D additions, total soil DNA was extracted and analyzed on Southern blots by using a tfdA gene probe which detected three of the strains and another probe that detected the fourth strain, S. paucimobilis 1443, which belongs to a different …

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