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Biological Sciences Faculty Publications

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Articles 1471 - 1500 of 1571

Full-Text Articles in Life Sciences

The Latent Tendencies Of Pai-1, Stephen R. Sprang Feb 1992

The Latent Tendencies Of Pai-1, Stephen R. Sprang

Biological Sciences Faculty Publications

No abstract provided.

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Seasonal Phytoplankton Development Within Three Rivers In The Lower Chesapeake Bay Region, Harold G. Marshall, Lewis F. Affronti Jan 1992

Seasonal Phytoplankton Development Within Three Rivers In The Lower Chesapeake Bay Region, Harold G. Marshall, Lewis F. Affronti

Biological Sciences Faculty Publications

The seasonal and inter-annual concentrations of phytoplankton were studied over a 50 month period in the lower James, York and Rappahannock Rivers (USA). Differences in the onset, duration and magnitude of major seasonal growth periods varied from year to year. There was a tendency for spring, summer and fall maxima, with a winter period of reduced abundance. An additional study of picoplankton over a 12 month period indicated greatest abundance during summer and fall, with least development in winter.

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Spiny Lobster Recruitment In South Florida: Quantitative Experiments And Management Implications, Mark J. Butler Iv, William F. Herrnkind Jan 1992

Spiny Lobster Recruitment In South Florida: Quantitative Experiments And Management Implications, Mark J. Butler Iv, William F. Herrnkind

Biological Sciences Faculty Publications

Understanding recruitment and identifying factors critical to that process are imperative if adult spiny lobster Panulirus argus stocks are to be conserved and properly managed. The goal of our research has been to obtain ecological information linking inshore postlarval spiny lobster recruitment to later life stages, thereby providing the basic framework for assessing and predicting adult stock. Since 1983, we have investigated various aspects of spiny lobster recruitment including: postlarval time-to-metamorphosis, postlarval/juvenile habitat selection and selection cues, postlarval/juvenile crypticity and susceptibility to predation, juvenile food preference and emigration, juvenile sociality, and the effect of habitat degradation (i.e., siltration) on postlarval/juvenile …

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A Plasmid-Encoded Surface Protein Found In Chronic-Disease Isolates Of Coxiella Burnetti, Michael F. Minnick, Robert A. Heinzin, Dennis K. Reschke, Marvin Eugene Frazier, Louis P. Mallavia Dec 1991

A Plasmid-Encoded Surface Protein Found In Chronic-Disease Isolates Of Coxiella Burnetti, Michael F. Minnick, Robert A. Heinzin, Dennis K. Reschke, Marvin Eugene Frazier, Louis P. Mallavia

Biological Sciences Faculty Publications

The cbbE' gene codes for the E' protein of Coxiella burnetii and was detected in genomic DNA from all known human isolates of the biotzere strain but not in DNA from the other five strains of C. burnetti. The biotzere strain is strictly associated with chronic disease in humans. Extrinsic iodination of biotzere strain cells radiolabeled a 55-kDa protein which comigrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the E' protein synthesized in vitro from recombinants containing the cbbE' gene. The 125I-labeled 55-kDa protein was immunoprecipitated with polyclonal anti-E' antiserum, confirming its identity as E'. Predicted secondary structure of the …

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Bird Populations In Logged And Unlogged Western Larch/Douglas-Fir Forest In Northwestern Montana, Bret W. Tobalske, Richard L. Hutto, Raymond C. Shearer May 1991

Bird Populations In Logged And Unlogged Western Larch/Douglas-Fir Forest In Northwestern Montana, Bret W. Tobalske, Richard L. Hutto, Raymond C. Shearer

Biological Sciences Faculty Publications

Of 32 species of abundant breeding birds, populations of 10 species differed significantly between small cutting units and adjacent uncut forest. Foliage foragers and tree gleaners were less abundant in cutting units, while flycatching species and ground foragers were more common there. Of nesting guilds, conifer tree nesters were least abundant in cutting units, and ground nesters were more common there. Results suggest that bird management should consider diverse community-level habitat needs and that if maintenance of tree-dependent species is important, broadleaf trees and snags of all species should be retained.

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Three-Dimensional Structure Of Human Basic Fibroblast Growth Factor, A Structural Homolog Of Interleukin 1Β, Jiandong Zhang, Lawrence S. Cousens, Phillip J. Barr, Stephen R. Sprang Apr 1991

Three-Dimensional Structure Of Human Basic Fibroblast Growth Factor, A Structural Homolog Of Interleukin 1Β, Jiandong Zhang, Lawrence S. Cousens, Phillip J. Barr, Stephen R. Sprang

Biological Sciences Faculty Publications

The three-dimensional structure of the 146-residue form of human basic fibroblast growth factor (bFGF), expressed as a recombinant protein in yeast, has been determined by x-ray crystallography to a resolution of 1.8 Å. bFGF is composed entirely of β-sheet structure, comprising a three-fold repeat of a four-stranded antiparallel β-meander. The topology of bFGF is identical to that of interleukin 1β, showing that although the two proteins share only 10% sequence identity, bFGF, interleukin 1, and their homologs comprise a family of structurally related mitogenic factors. Analysis of the three-dimensional structure in light of functional studies of bFGF suggests that the …

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Life-History Correlates Of Taxonomic Diversity, John M. Marzluff, Kenneth P. Dial Apr 1991

Life-History Correlates Of Taxonomic Diversity, John M. Marzluff, Kenneth P. Dial

Biological Sciences Faculty Publications

One of the most pervasive, nonrandom evolutionary patterns is extreme domination of a taxon by one subtaxon or only a few subtaxa. Domination refers to taxonomic diversity and the fraction of the taxon that is classified in the most diverse subtaxon. We attempt to explain how subtaxa come to dominate their phyletic counterparts by examining correlations between taxonomic diversity and life history traits such as age of first reproduction, longevity, fecundity and partitioning of reproduction, and resource availability in a variety of vertebrate, invertebrate, and plant groups. Regardless of taxonomic group or rank, the number of taxa within an assemblage, …

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Identification Of Adaptive Changes In An Evolving Population Of Escherichia Coli: The Role Of Changes With Regulatory And Highly Pleiotropic Effects, A. Kurlandzka, Frank Rosenzweig, J. Adams Mar 1991

Identification Of Adaptive Changes In An Evolving Population Of Escherichia Coli: The Role Of Changes With Regulatory And Highly Pleiotropic Effects, A. Kurlandzka, Frank Rosenzweig, J. Adams

Biological Sciences Faculty Publications

A population of Escherichia coli initiated with a single clone developed extensive morphological and physiological polymorphism after being maintained for 773 generations in glucose-limited continuous culture. To understand the mechanisms of adaptation to this environment, total protein patterns of four adaptive clones and of the parent strains were examined by two-dimensional gel electrophoresis. Approximately 20% of the proteins (approximately 160 in absolute numbers) showed significantly different levels of expression in pairwise comparisons of parent and adapted clones. The extent of these changes points to the importance of mutations with regulatory and/or highly pleiotropic effects in the adaptive process. The four …

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Shrimp Stocking, Salmon Collapse, And Eagle Displacement, Craig N. Spencer, B. Riley Mcclelland, Jack Arthur Stanford Jan 1991

Shrimp Stocking, Salmon Collapse, And Eagle Displacement, Craig N. Spencer, B. Riley Mcclelland, Jack Arthur Stanford

Biological Sciences Faculty Publications

No abstract provided.

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Sediment Denitrification Potential In The Elizabeth River, Virginia, Surena Fazeli-Matin, Andrew S. Gordon, Harold G. Marshall Jan 1991

Sediment Denitrification Potential In The Elizabeth River, Virginia, Surena Fazeli-Matin, Andrew S. Gordon, Harold G. Marshall

Biological Sciences Faculty Publications

Sediment denitrification potential from two sites in the Elizabeth River estuary was studied over a nine-month period using the acetylene blockage method. Rates of microbial processes in this environment are of interest because of the high concentration of toxics present in some parts of the system. Highest rates were found in the highly polluted Southern Branch of the Elizabeth River with nitrate amended sediment ranging from 2-262 nmol N20/h per 20ml of sediment and exhibiting maximal rates during spring and fall. Rates in the Main Stem of the Elizabeth River were lower, with less than 1-85 nmol N …

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Observations Of The Phytoplankton Standing Crop At The Shelf Margin Of The Mid Atlantic Bight, Bruce B. Wagoner, Harold G. Marshall Jan 1991

Observations Of The Phytoplankton Standing Crop At The Shelf Margin Of The Mid Atlantic Bight, Bruce B. Wagoner, Harold G. Marshall

Biological Sciences Faculty Publications

A comparison of the total percentage cell abundance and cell biovolume relationships of major phytoplankton categories was made between two station sets across the shelf margin. Diatom values for abundance and biovolume were greater at oceanic stations compared to the outer shelf stations, with dinoflagellates having the reverse pattern. The composite contributions to biovolume and abundance in the standing crop from other phytoplankton categories were greater over the outer shelf than beyond the shelf margin. The major source of biovolume (biomass) from the outer shelf and these oceanic stations came from the diatoms and dinoflagellates, with an average mean of …

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Feeding By Reticulitermes Spp., Deborah A. Waller Jan 1991

Feeding By Reticulitermes Spp., Deborah A. Waller

Biological Sciences Faculty Publications

No abstract provided.

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Intracellular Ph Decreases During Entry Into Estivation In The Land Snail Oreohelix, Bernard Rees Jan 1991

Intracellular Ph Decreases During Entry Into Estivation In The Land Snail Oreohelix, Bernard Rees

Biological Sciences Faculty Publications

No abstract provided.

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Seasonal Phytoplankton Assemblages Associated With The Chesapeake Bay Plume, Harold G. Marshall Jan 1991

Seasonal Phytoplankton Assemblages Associated With The Chesapeake Bay Plume, Harold G. Marshall

Biological Sciences Faculty Publications

Waters associated with the Chesapeake Bay plume were highly variable, unstable, and subject to the influence of flow patterns into and out of the Bay. Seasonal phytoplankton assemblages were identified for this region, with the phytoplankton development similar to the seasonal spring-fall growth maxima over the shelf, yet influenced by the multi-pulsed patterns often noted in the lower Bay. Major dominants included species common to both the shelf and lower Chesapeake Bay.

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The Divergent Receptors For Tnf, Stephen R. Sprang Oct 1990

The Divergent Receptors For Tnf, Stephen R. Sprang

Biological Sciences Faculty Publications

No abstract provided.

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Reproduction In The Hispid Cotton Rat, Sigmodon-Hispidus Say And Ord (Rodentia: Muridae), In Southeastern Virginia, Robert K. Rose, Michael H. Mitchell Jul 1990

Reproduction In The Hispid Cotton Rat, Sigmodon-Hispidus Say And Ord (Rodentia: Muridae), In Southeastern Virginia, Robert K. Rose, Michael H. Mitchell

Biological Sciences Faculty Publications

The hispid cotton rat, Sigmodon hispidus Say and Ord, a species of the southwestern United States that has been moving northward and eastward in this century, was first observed in Virginia in 1940. In this study of the cotton rat in southeastern Virginia, most males were reproductively competent from February through November, embryos were recorded from March through October, and litter sizes were comparable to those from other locations except Kansas. Also unlike the cotton rat in Kansas, animals grew at substantial rates during the winter in Virginia. The hispid cotton rat seems to have adjusted its breeding season in …

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Small Mammals In The Great Dismal Swamp Of Virginia And North Carolina, Robert K. Rose, Roger K. Everton, Jean F. Stankavich Jul 1990

Small Mammals In The Great Dismal Swamp Of Virginia And North Carolina, Robert K. Rose, Roger K. Everton, Jean F. Stankavich

Biological Sciences Faculty Publications

Small" mammals were surveyed in a range of habitats in the Great Dismal Swamp of Virginia and North Carolina. The survey is based on three chronologically overlapping studies, each lasting 15-18 months and for which the results have been reported separately. A different trapping method was used in each of the three studies: nest boxes, Fitch live traps, or pitfall traps. Only two species of mammals, both arboreal, were taken in nest boxes, compared with 10 and 9 species in Fitch live traps and pitfall traps, respectively. The Fitch live traps had a much higher catch rate per 1,000 trap-nights …

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Characterization And Expression Of The Cbbe' Gene Of Coxiella Burnetii, Michael F. Minnick, Robert A. Heinzin, Marvin Eugene Frazier, Louis P. Mallavia Jun 1990

Characterization And Expression Of The Cbbe' Gene Of Coxiella Burnetii, Michael F. Minnick, Robert A. Heinzin, Marvin Eugene Frazier, Louis P. Mallavia

Biological Sciences Faculty Publications

A gene which is unique to the QpRS plasmid from chronic isolates of Coxiella burnetii was cloned, sequenced, and expressed in Escherichia coli. This gene, termed cbbE', codes for a putative surface protein of approximately 55 kDa, termed the E' protein. The cbbE' gene is 1485 bp in length, and is preceded by predicted promoter regulatory sequences of TTTAAT (-35), TATAAT (-10), and a Shine-Dalgarno sequence of GGAGAGA, all of which closely resemble those of E. coli and other rickettsiae. The open reading frame (ORF) of cbbE' ends with a UAA codon followed by a second in-frame UAG stop codon …

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Bird Flight - Insights And Complications, G. E. Goslow Jr., Kenneth P. Dial, F. A. Jenkins Jr. Feb 1990

Bird Flight - Insights And Complications, G. E. Goslow Jr., Kenneth P. Dial, F. A. Jenkins Jr.

Biological Sciences Faculty Publications

No abstract provided.

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Migration Routes Of New World Sanderlings (Calidris Alba), J. P. Meyers, M. Sallaberry A., E. Ortiz, G. Castro, L. J. Gordon, John L. Maron, C. T. Schick, E. Tablio, P. Antas, T. Below Jan 1990

Migration Routes Of New World Sanderlings (Calidris Alba), J. P. Meyers, M. Sallaberry A., E. Ortiz, G. Castro, L. J. Gordon, John L. Maron, C. T. Schick, E. Tablio, P. Antas, T. Below

Biological Sciences Faculty Publications

We color-marked Sanderlings (Calidris alba Pallas) at 19 locations in 6 countries in the New World and coordinated a network of volunteers to locate banded individuals in migration over a five-year period. The observers reported 252 independent sightings of birds in countries different from the country of banding. Sanderlings that migrate north to the Arctic from Chile and Peru travel principally through the central corridor (Texas and northward) of the United States and Canada; smaller numbers follow the Pacific coast. A few migrate north from the Pacific coast of South America along the Atlantic coast of the United …

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Heat Dissipation, Gas Exchange And Acid-Basic Balance In The Land Snail Oreohelix During Short-Term Estivation, Bernard Rees Jan 1990

Heat Dissipation, Gas Exchange And Acid-Basic Balance In The Land Snail Oreohelix During Short-Term Estivation, Bernard Rees

Biological Sciences Faculty Publications

Within 4 days following entry into estivation, heat dissipation and oxygen consumption by the land snail Oreohelix spp. decreased by 83 % compared to standard non-estivating rates. During both non-estivating and estivating conditions, the quantity of heat dissipated per mole of O2 consumed was indicative of a completely aerobic metabolism. This calorimetric-respirometric (C/R) ratio was — 461 ± 12 kJ moP102 (S.E.M., N=5) under standard non-estivating conditions and — 464±26kJmol~1O2 (7V=4) during estivation. Respiratory exchange ratios reflected a primary dependence upon carbohydrate as a metabolic substrate during both states. Carbon dioxide retention occurred during the first 36h of estivation, resulting …

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Identification And Characterization Of Peptidoglycan-Associated Proteins In Neisseria-Gonorrhoeae, Stuart A. Hill, Ralph C. Judd Nov 1989

Identification And Characterization Of Peptidoglycan-Associated Proteins In Neisseria-Gonorrhoeae, Stuart A. Hill, Ralph C. Judd

Biological Sciences Faculty Publications

The principal proteins associated with Neisseria gonorrhoeae peptidoglycan (PG), as identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, are the following: two proteins at approximately 90 kilodaltons (kDa), single major species at both 60 and 44 kDa, a 34- to 36-kDa protein, and three proteins between 28 and 32 kDa. A protein analogous to Escherichia coli Braun lipoprotein was not detected with gonococcal cell wall preparations. The identity of the PG-associated proteins was confirmed immunologically with antibody generated against purified cell walls. Two types of protein species, dithiothreitol extractable (the majority) and alkylation dependent (primarily the 34- to 36-kDa protein), appeared …

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Detection In Soil Of A Deletion In An Engineered Dna Sequence By Using Dna Probes, Janet K. Jansson, William E. Holben, James M. Tiedje Nov 1989

Detection In Soil Of A Deletion In An Engineered Dna Sequence By Using Dna Probes, Janet K. Jansson, William E. Holben, James M. Tiedje

Biological Sciences Faculty Publications

Two Pseudomonas strains were engineered to contain the nptII gene and plasmid vector sequences in their chromosomes. After incubation of these strains in nonsterile soil, total bacterial DNA was isolated and analyzed by Southern blot hybridization with the nptII gene and the plasmid vector as probes. In addition to the expected bands of hybridization, a new band corresponding to the loss of vector sequences from the chromosome while retaining the nptII gene was observed for one of the strains. The more stressful conditions encountered in soil appeared to increase the frequency of loss of the vector sequences …

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The Structure Of Tumor Necrosis Factor-Α At 2.6 Å Resolution. Implications For Receptor Binding, M. J. Eck, S. R. Sprang Oct 1989

The Structure Of Tumor Necrosis Factor-Α At 2.6 Å Resolution. Implications For Receptor Binding, M. J. Eck, S. R. Sprang

Biological Sciences Faculty Publications

The three-dimensional structure of tumor necrosis factor (TNF-α), a protein hormone secreted by macrophages, has been determined at 2.6 Å resolution by x-ray crystallography. Phases were determined by multiple isomorphous replacement using data collected from five heavy atom derivatives. The multiple isomorphous replacement phases were further improved by real space symmetry averaging, exploiting the non-crystallographic 3-fold symmetry of the TNF-α trimer. An atomic model corresponding to the known amino acid sequence of TNF-α was readily built into the electron density map calculated with these improved phases. The 17,350-dalton monomer forms an elongated, antiparallel β-pleated sheet sandwich with a 'jelly-roll' topology. …

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Micronuclear Genome Organization In Euplotes Crassus: A Transposonlike Element Is Removed During Macronuclear Development, Scott Everet Baird, Gina M. Fino, Susan L. Tausta, Lawrence A. Klobutcher Sep 1989

Micronuclear Genome Organization In Euplotes Crassus: A Transposonlike Element Is Removed During Macronuclear Development, Scott Everet Baird, Gina M. Fino, Susan L. Tausta, Lawrence A. Klobutcher

Biological Sciences Faculty Publications

After mating, hypotrichous ciliated protozoa transform a set of their micronuclear chromosomes into thousands of short, linear DNA molecules that form the macronuclear genome. To examine micronuclear genome organization in the hypotrich Euplotes crassus, we have analyzed two cloned segments of micronuclear DNA as well as the macronuclear DNA molecules that are derived from them. E. crassus was found to display a number of features characteristic of other hypotrich genomes, including (i) clustering and close spacing of the precursors of macronuclear DNA molecules, (ii) the frequent occurrence of internal eliminated sequences within macronuclear precursors, (iii) overlapping macronuclear precursors, (iv) lack …

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Kinetic Properties Of Hexokinase Under Near-Physiological Conditions: Relation To Metabolic Arrest In Artemia Embryos During Anoxia, Bernard Rees Sep 1989

Kinetic Properties Of Hexokinase Under Near-Physiological Conditions: Relation To Metabolic Arrest In Artemia Embryos During Anoxia, Bernard Rees

Biological Sciences Faculty Publications

Previous analyses of glycolytic metabolites in Artemia embryos indicate that an acute inhibition of glucose phosphorylation occurs during pHi-mediated metabolic arrest under anoxia. We describe here kinetic features of hexokinase purified from brine shrimp embryos in an attempt to explain the molecular basis for this inhibition. At saturating concentrations of cosubstrate, ADP is an uncompetitive inhibitor toward glucose and a partial noncompetitive inhibitor toward ATP (Kis = 0.86 mM, Kii = 1.0 mM, Kid = 1.9 mM). With cosubstrates at subsaturating concentrations, the uncompetitive inhibition versus glucose becomes noncompetitive, while inhibition versus ATP remains partial noncompetitive. The partial noncompetitive inhibition …

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Isolation, Growth Characteristics, And Long-Term Storage Of Fungi Cultivated By Attine Ants, Jerome J. Howard Jun 1989

Isolation, Growth Characteristics, And Long-Term Storage Of Fungi Cultivated By Attine Ants, Jerome J. Howard

Biological Sciences Faculty Publications

Seven pure-culture strains of fungi cultivated by attine ants (ant-garden fungi) were isolated from locally maintained leaf-cutting ant colonies. An ant-garden fungus strain obtained from an Atta cephalotes colony, when offered to ants of the colony from which the fungus was isolated, was accepted as their own. Young fungus cultures were harvested and incorporated into the fungus garden, and cultures of intermediate age were used to begin a new fungus garden; old cultures were simply harvested. To facilitate further research on this fungus, growth characteristics of the different isolates were studied under a variety of conditions. They grew better at …

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Export And Intercellular Transfer Of Dna Via Membrane Blebs Of Neisseria-Gonorrhoeae, David W. Dorward, Claude F. Garon, Ralph C. Judd May 1989

Export And Intercellular Transfer Of Dna Via Membrane Blebs Of Neisseria-Gonorrhoeae, David W. Dorward, Claude F. Garon, Ralph C. Judd

Biological Sciences Faculty Publications

Naturally elaborated membrane bleb material is frequently observed in cultures of Neisseria gonorrhoeae. This material was purified and analyzed for protein, lipopolysaccharide, and nucleic acid content. The electrophoretic protein profiles of two bleb-rich fractions, called BI and BII, were distinct, with only BII containing lipopolysaccharide and outer membrane proteins I and III. Both fractions contained RNA, circular DNA, and linear DNA. Exogenous pancreatic DNase I appeared to hydrolyze all bleb-associated DNA in fraction BI and the linear DNA in fraction BII. The circular DNA molecules associated with fraction BII resisted digestion. Electron microscopy of the bleb fractions verified their DNA …

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Protein I: Structure, Function, And Genetics, Ralph C. Judd Apr 1989

Protein I: Structure, Function, And Genetics, Ralph C. Judd

Biological Sciences Faculty Publications

No abstract provided.

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Characterization Of Chromosome Fragmentation In Two Protozoans And Identification Of A Candidate Fragmentation Sequence In Euplotes Crassus, Scott Everet Baird, Lawrence A. Klobutcher Jan 1989

Characterization Of Chromosome Fragmentation In Two Protozoans And Identification Of A Candidate Fragmentation Sequence In Euplotes Crassus, Scott Everet Baird, Lawrence A. Klobutcher

Biological Sciences Faculty Publications

Following the sexual cycle, hypotrichous ciliated protozoans fragment a set of their micronuclear chromosomes to generate the thousands of short, linear DNA molecules present in the transcriptionally active macronucleus. We have used a hybrid selection procedure to examine macronuclear DNA molecules for subtelomeric length heterogeneity to determine whether chromosome fragmentation occurs at unique or multiple sites. The results suggest that multiple, but closely spaced, chromosome fragmentation sites are used by Oxytricha nova. In contrast, Euplotes crassus uses unique chromosome fragmentation sites in a reproducible manner to generate the ends of macronuclear DNA molecules. Additional studies compared DNA sequences in …

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