Life Sciences Commons^™

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 …

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 …

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. …

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 …

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 …

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 …

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 …

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

Biological Sciences Faculty Publications

No abstract provided.

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 …

Phytoplankton Composition In A Borrow Pit Lake In Virginia, Seba B. Sheavly, Harold G. Marshall

Biological Sciences Faculty Publications

The phytoplankton assemblages in Lake Trashmore, Virginia, a borrow pit, were dominated by centric diatoms and cyanobacteria, with seasonal pulses of cryptomonads, euglenoids, and chlorophyceans. Ninety species were identified and their abundance levels noted for a 12-month period.

Are Artificial "Witham" Surface Collectors Adequate Indicators Of Caribbean Spiny Lobster, Panulirus Argus, Recruitment?, Mark J. Butler Iv, William F. Herrnkind

Biological Sciences Faculty Publications

Understanding the local dynamics of Caribbean spiny lobster (Panulirus argus) postlarval influx, settlement, and recruitment may be essential for the responsible management of this important and heavily exploited resource. Most lobster recruitment research programs in the Caribbean employ derivations of the "Witham"-type surface collector to monitor postlarval (puerulus) lobster influx. However, the relevance of data obtained from surface collectors with respect to the estimation of actual puerulus influx, settlement, or recruitment to subsequent benthic juvenile stages remains untested. We investigated that relevance on regional (i.e., tens of kilometers) and local (i.e., tens of meters) scales by examining the …

Community Responses To Variable Predation: Field Studies With Sunfish And Freshwater Macroinvertebrates, Mark J. Butler Iv

Biological Sciences Faculty Publications

The impact of variable predation by bluegill sunfish on macroinvertebrate prey in a North Florida lake is examined. Variable predation may occur in many systems and may contribute substantially to the spatial heterogeneity, temporal inconstancy and species composition of prey communities.

Patchy, temporally variable predation characterized middepth and deep lake habitats, whereas in the shallow zone predation was relatively constant and homogeneous. Predation varied significantly every 2-4 wk in the mid-depth zone, but varied little between consecutive weeks or days. Caging experiments revealed that variable predation altered prey community composition and increased the mean size and size range of some …