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Biological Sciences Faculty Publications

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Articles 1441 - 1470 of 1571

Full-Text Articles in Life Sciences

Genetic And Phenotypic Diversity Of 2,4-Dichlorophenoxyacetic Acid (2,4-D)-Degrading Bacteria Isolated From 2,4-D-Treated Field Soils, J. O. Ka, William E. Holben, James M. Tiedje Apr 1994

Genetic And Phenotypic Diversity Of 2,4-Dichlorophenoxyacetic Acid (2,4-D)-Degrading Bacteria Isolated From 2,4-D-Treated Field Soils, J. O. Ka, William E. Holben, James M. Tiedje

Biological Sciences Faculty Publications

Forty-seven numerically dominant 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria were isolated at different times from 1989 through 1992 from eight agricultural plots (3.6 by 9.1 m) which were either not treated with 2,4-D or treated with 2,4-D at three different concentrations. Isolates were obtained from the most dilute positive most-probable-number tubes inoculated with soil samples from the different plots on seven sampling dates over the 3-year period. The isolates were compared by using fatty acid methyl ester (FAME) profiles, chromosomal patterns obtained by PCR amplification of repetitive extragenic palindromic (REP) sequences, and hybridization patterns obtained with probes for the tfd genes of …

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The Composition And Social-Organization Of Mixed-Species Flocks In A Tropical Deciduous Forest In Western Mexico, Richard L. Hutto Feb 1994

The Composition And Social-Organization Of Mixed-Species Flocks In A Tropical Deciduous Forest In Western Mexico, Richard L. Hutto

Biological Sciences Faculty Publications

I recorded the flocking propensity of birds within a tropical deciduous forest in western Mexico during the nonbreeding season, and determined the species composition of 57 mixed-species, canopy insectivore flocks. Each of 27 canopy insectivore species present on the study area was observed foraging in mixed-species flocks on at least half of the occasions that it was detected on bird surveys. The proportion of flocks within which a given species was detected could be predicted on the basis of its index of abundance, as determined from independently derived point count data. Therefore, flocks are not comprised of a special subset …

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Crystallization And Preliminary Crystallographic Studies Of Giα1 And Mutants Of Giα1 In The Gtp And Gdp-Bound States, David E. Coleman, Ethan Lee, Mark B. Mixon, Maurine E. Linder, Albert M. Berghuis, Alfred G. Gilman, Stephen R. Sprang Jan 1994

Crystallization And Preliminary Crystallographic Studies Of Giα1 And Mutants Of Giα1 In The Gtp And Gdp-Bound States, David E. Coleman, Ethan Lee, Mark B. Mixon, Maurine E. Linder, Albert M. Berghuis, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

Several different crystal forms of Giα1 have been grown and analyzed. Crystals of native protein containing bound GTPγS belong to space group P3121 or P3221 with cell dimensions a, b = 80·6 Åand c = 106·3 Å and diffract to a resolution of 1·9 Å using synchrotron radiation. Crystals of native protein containing bound GDP belong to space group I4 with cell dimensions a, b = 121·3 Å, and c = 67·7 Å and diffract to 3·0Å. Data sets from crystals grown using mutant proteins have also been obtained and characterized.

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Two Crystal Forms Of The Extracellular Domain Of Type I Tumor Necrosis Factor Receptor, Lynn E. Rodseth, Barbara Brandhuber, Tracey Q. Devine, Michael J. Eck, Karin Hale, James H. Naismith, Stephen R. Sprang Jan 1994

Two Crystal Forms Of The Extracellular Domain Of Type I Tumor Necrosis Factor Receptor, Lynn E. Rodseth, Barbara Brandhuber, Tracey Q. Devine, Michael J. Eck, Karin Hale, James H. Naismith, Stephen R. Sprang

Biological Sciences Faculty Publications

The soluble extracellular domain of human type I tumor necrosis factor receptor (sTNFrI) is a 161 residue polypeptide found in serum and urine. This domain tightly binds tumor necrosis factors (TNF) α and β and, as part of the whole receptor, initiates the powerful biological effects of TNF. The extracellular domain, typical of other TNF receptor superfamily members, comprises four cysteine-rich motifs. We have obtained two crystal forms of the sTNFrI. One crystal form is grown at pH 3.7 with MgSO4 as the precipitant. These crystals are orthorhombic, space group P212121, with cell …

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Population-Dynamics Of Juvenile Caribbean Spiny Lobster, Panulirus-Argus, In Florida Bay, Florida, David Forcucci, Mark J. Butler Iv, John H. Hunt Jan 1994

Population-Dynamics Of Juvenile Caribbean Spiny Lobster, Panulirus-Argus, In Florida Bay, Florida, David Forcucci, Mark J. Butler Iv, John H. Hunt

Biological Sciences Faculty Publications

Despite a wealth of information on the growth and population dynamics of sub-adult and adult Caribbean spiny lobsters (Panulirus argus), there is far less information about younger juveniles under natural conditions. Here we describe growth and population dynamics of juvenile spiny lobsters (12-68 mm carapace length, CL) that we have studied for 14 months (October 1988-December 1989) using mark-recapture techniques in a hardbottom community in Florida Bay, Florida. We also monitored the supply of postlarvae into the region in 1988 and 1989 using Witham-type surface collectors in an effort to link peak periods of settlement of postlarvae with subsequent cohorts …

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Chesapeake Bay Phytoplankton: I. Composition, Harold G. Marshall Jan 1994

Chesapeake Bay Phytoplankton: I. Composition, Harold G. Marshall

Biological Sciences Faculty Publications

A list of 708 Phytoplankton taxa from 10 algal divisions has been compiled for the Chesapeake Bay and is based on the analysis of 2384 water samples over three decades of study.

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Characterization Of Bartonella-Bacilliformis Flagella And Effect Of Antiflagellin Antibodies On Invasion Of Human Erythrocytes, David C. Scherer, Isaure Deburon-Connors, Michael F. Minnick Dec 1993

Characterization Of Bartonella-Bacilliformis Flagella And Effect Of Antiflagellin Antibodies On Invasion Of Human Erythrocytes, David C. Scherer, Isaure Deburon-Connors, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella bacilliformis is the etiologic agent of Oroya fever in humans. Flagellum-mediated motility has been postulated as a major virulence factor for invasion of host cells. To address this hypothesis, we purified and characterized flagella from strain KC584 and then assessed their role in human erythrocyte association and invasion. Electron microscopy of the flagellar preparation showed a high concentration of filaments with a mean wavelength of 800 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis, and KBr density gradient centrifugation indicated that the flagellar filament is composed of a polypeptide of 42 kDa. The flagellin is partially (ca. 50%) resistant …

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Affinity Panning Of A Library Of Peptides Displayed On Bacteriophages Reveals The Binding Specificity Of Bip, Sylvie Blond-Elguindi, Steven E. Cwirla, William J. Dower, Robert J. Lipshutz, Stephen R. Sprang, Joseph F. Sambrook, Mary Jane H. Gething Nov 1993

Affinity Panning Of A Library Of Peptides Displayed On Bacteriophages Reveals The Binding Specificity Of Bip, Sylvie Blond-Elguindi, Steven E. Cwirla, William J. Dower, Robert J. Lipshutz, Stephen R. Sprang, Joseph F. Sambrook, Mary Jane H. Gething

Biological Sciences Faculty Publications

We have used affinity panning of libraries of bacteriophages that display random octapeptide or dodecapeptide sequences at the N-terminus of the adsorption protein (plll) to characterize peptides that bind to the endoplasmic reticulum chaperone BiP and to develop a scoring system that predicts potential BiP-binding sequences in naturally occurring polypeptides. BiP preferentially binds peptides containing a subset of aromatic and hydrophobic amino acids in alternating positions, suggesting that peptides bind in an extended conformation, with the side chains of alternating residues pointing into a cleft on the BiP molecule. Synthetic peptides with sequences corresponding to those displayed by BiP-binding bacteriophages …

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Identification Of A Protein In Several Borrelia Species Which Is Related To Ospc Of The Lyme Disease Spirochetes., Richard T. Marconi, D. Scott Samuels, Tom G. Schwan, Claude F. Garon Oct 1993

Identification Of A Protein In Several Borrelia Species Which Is Related To Ospc Of The Lyme Disease Spirochetes., Richard T. Marconi, D. Scott Samuels, Tom G. Schwan, Claude F. Garon

Biological Sciences Faculty Publications

Using oligonucleotide probes which have previously been shown to be specific for the ospC gene found in the Lyme disease spirochete species Borrelia burgdorferi, B. garinii, and group VS461, we detected an ospC homolog in other Borrelia species including B. coriaceae, B. hermsii, B. anserina, B. turicatae, and B. parkeri. In contrast to the Lyme disease spirochetes, which carry the ospC gene on a 26-kb circular plasmid, we mapped the gene in other Borrelia species to linear plasmids which varied in size among the isolates tested. Some isolates carry multiple copies of the gene residing on linear plasmids of different …

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On A (Β-) Roll, S. R. Sprang Sep 1993

On A (Β-) Roll, S. R. Sprang

Biological Sciences Faculty Publications

No abstract provided.

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Nucleotide Sequence And Comparison Of The 5s Ribosomal Rna Genes Of Rochalimaea Henselae, R-Quintana And Brucella Abortus, Michael F. Minnick, Gary L. Stiegler May 1993

Nucleotide Sequence And Comparison Of The 5s Ribosomal Rna Genes Of Rochalimaea Henselae, R-Quintana And Brucella Abortus, Michael F. Minnick, Gary L. Stiegler

Biological Sciences Faculty Publications

No abstract provided.

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Biochemical Correlates Of Estivation Tolerance In The Mountainsnail Oreohelix (Pulmonata: Oreohelicidae), Bernard Rees Apr 1993

Biochemical Correlates Of Estivation Tolerance In The Mountainsnail Oreohelix (Pulmonata: Oreohelicidae), Bernard Rees

Biological Sciences Faculty Publications

Biochemical changes occurring over 7 months of estivation were studied in two species of land snail, Oreohelix strigosa (Gould) and 0. subrudis (Reeve), to determine whether differential mortality during estivation is related to different energetic strategies. Laboratory- maintained snails, which were fed ad libitum prior to es- tivation, were compared with snails collected from the field and induced to estivate without augmenting their energy reserves. In all groups, polysaccharide was catab- olized early in estivation, and protein was the primary metabolic substrate after polysaccharide reserves were de- pleted. Lipid was catabolized at a low rate throughout estivation. Rates of catabolism …

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Breeding Ground Fidelity And Mate Retention In The Pacific Golden-Plover, Oscar W. Johnson, Peter G. Connors, Phillip L. Bruner, John L. Maron Mar 1993

Breeding Ground Fidelity And Mate Retention In The Pacific Golden-Plover, Oscar W. Johnson, Peter G. Connors, Phillip L. Bruner, John L. Maron

Biological Sciences Faculty Publications

We found male-biased site fidelity in Pacific Golden-Plovers (Phviah fulva)
on breeding grounds in western Alaska. Males (8 of 8) returned to the same territories annually, while few females (1 of 4) were seen in subsequent seasons. Nest sites in successive years were usually within 100 m, and the same nest cup may be used in more than one year. First-year birds of both sexes mated with older birds and also with each other, but first-year females may breed less commonly than first-year males. The numbers of nesting birds on our study sites varied sharply both within and …

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Nucleotide Sequence Of The 5s Ribosomal Rna Gene Of Bartonella Bacilliformis, Michael F. Minnick Feb 1993

Nucleotide Sequence Of The 5s Ribosomal Rna Gene Of Bartonella Bacilliformis, Michael F. Minnick

Biological Sciences Faculty Publications

No abstract provided.

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Transcriptional Analyses And Mapping Of The Ospc Gene In Lyme Disease Spirochetes, Richard T. Marconi, D. Scott Samuels, Claude F. Garon Feb 1993

Transcriptional Analyses And Mapping Of The Ospc Gene In Lyme Disease Spirochetes, Richard T. Marconi, D. Scott Samuels, Claude F. Garon

Biological Sciences Faculty Publications

In Lyme disease spirochetes, the ospC gene encodes a 22.7-kDa protein referred to as either the pC or the OspC protein. Using a variety of electrophoretic approaches followed by Southern blotting and probing with oligonucleotide probes, we mapped the ospC gene to a circular 26-kb plasmid. The ospC gene represents the first gene to be mapped to a circular plasmid in Lyme disease spirochetes. The occurrence of this gene in isolates belonging to each of the three Lyme disease-associated species, Borrelia burgdorferi, Borrelia garinii, and the VS461 group, was evaluated. The ospC gene was found to occur in all 21 …

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Cytokine Structural Taxonomy And Mechanisms Of Receptor Engagement, Stephen R. Sprang, J. Fernando Bazan Jan 1993

Cytokine Structural Taxonomy And Mechanisms Of Receptor Engagement, Stephen R. Sprang, J. Fernando Bazan

Biological Sciences Faculty Publications

Seven discrete families of cytokines have been identified by sequence and structural analysis. Within this diverse set of protein folds, the hematopoietic growth factors and tumor necrosis factor-like cytokines display a remarkable degree of variation upon their respective topological frameworks. In addition, prototype X-ray structures of ligand-receptor complexes reveal two different strategies of receptor engagement.

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Effects Of Silvicultural Treatments On Forest Birds In The Rocky Mountains: Implications And Management Recommendations, Richard L. Hutto, Sallie J. Hejl, Charles R. Preston, Deborah M. Finch Jan 1993

Effects Of Silvicultural Treatments On Forest Birds In The Rocky Mountains: Implications And Management Recommendations, Richard L. Hutto, Sallie J. Hejl, Charles R. Preston, Deborah M. Finch

Biological Sciences Faculty Publications

The short-term effects of timber harvesting practices on landbird species vary widely among species. Thus, the maintenance of populations of all species will require a long-term management strategy that involves maintenance of a variety of habitats over a broad landscape.

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Coumermycin A1 Inhibits Growth And Induces Relaxation Of Supercoiled Plasmids In Borrelia Burgdorferi, The Lyme Disease Agent, D. Scott Samuels, Claude F. Garon Jan 1993

Coumermycin A1 Inhibits Growth And Induces Relaxation Of Supercoiled Plasmids In Borrelia Burgdorferi, The Lyme Disease Agent, D. Scott Samuels, Claude F. Garon

Biological Sciences Faculty Publications

Coumermycin A1 is an inhibitor of DNA gyrase, an enzyme that catalyzes supercoiling of DNA and is required for bacterial DNA replication. We have investigated the activity of this coumarin antibiotic on Borrelia burgdorferi, a spirochete and the causative agent of Lyme disease. B. burgdorferi was more susceptible than many other eubacteria to coumermycin as well as novobiocin, another coumarin antibiotic; this contrasted with its relative resistance to the DNA gyrase inhibitors nalidixic acid, oxolinic acid, and ciprofloxacin. Coumermycin at 0.2 micrograms/ml inhibited the growth of B. burgdorferi B31 in BSK II medium. A 100-fold-lower concentration induced the relaxation of …

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Speciation In Golden-Plovers, Pluvialis Dominica And P. Fulva: Evidence From The Breeding Grounds, Peter G. Connors, Brian J. Mccaffery, John L. Maron Jan 1993

Speciation In Golden-Plovers, Pluvialis Dominica And P. Fulva: Evidence From The Breeding Grounds, Peter G. Connors, Brian J. Mccaffery, John L. Maron

Biological Sciences Faculty Publications

Two forms of golden-plover have long been considered subspecies, Pluvialis
dominica dominica and P. d. fulva. Prior studies have shown differences between forms in breeding distributions, wintering distributions, plumage, morphology, molt, and maturation schedules. We report clear and consistent differences in breeding vocalizations and nesting habitat, and strict assortative mating in areas of sympatry in western Alaska. These results indicate a greater degree of differentiation between the forms than was previously appreciated. They are appropriately treated as separate species and should be referred to under the names Pluvialis dominica, for the American Golden-Plover, and Pluvialis fulva, for …

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Observations On The Pearl Oyster Fishery Of Kuwait, S. M. Almatar, Kent E. Carpenter, R. Jackson, S. H. Alhazeem, A. H. Alsaffar, A. R. A. Ghaffar, C. Carpenter Jan 1993

Observations On The Pearl Oyster Fishery Of Kuwait, S. M. Almatar, Kent E. Carpenter, R. Jackson, S. H. Alhazeem, A. H. Alsaffar, A. R. A. Ghaffar, C. Carpenter

Biological Sciences Faculty Publications

The pearl oyster fishery of Kuwait was monitored daily from January 1989 to May 1990. Landings of pearl oysters in 1989 totaled 287 tons with a market value of U.S. $1.0 million. Commercial pearls (>3 mm) were estimated to be present in one of every 4200 oysters. Most of the pearl oysters landed were new recruits with hinge lengths between 40-56 mm. There was a curvilinear relationship between total weight and size of oysters (length) and the sex ratio approached 1:1. Spawning occurs throughout the year, with a spat settlement peak in early fall. Over the size range examined …

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Age, Growth, And Reproduction Of Tautog Tautoga Onitis (Labridae: Perciformes) From Coastal Waters Of Virginia, E. Brian Hostetter, Thomas A. Munroe Jan 1993

Age, Growth, And Reproduction Of Tautog Tautoga Onitis (Labridae: Perciformes) From Coastal Waters Of Virginia, E. Brian Hostetter, Thomas A. Munroe

Biological Sciences Faculty Publications

Tautog Tautoga onitis are gaining popularity in Virginia's coastal waters as a recreational and food fish. Adult tautog are seasonally abundant on inshore hard-bottom habitats (1-10 m) and inhabit offshore areas (10-75 m) year-round. Juveniles, especially newly-settled recruits, inhabit vegetated areas in shallow water (usually < 1 m). From March 1979 to July 1986, tautog were collected in lower Chesapeake Bay and nearby coastal waters to examine age, growth, and sexual maturation. Age estimates were determined from annular marks on opercle bones: 82% of the fish were age-10 or younger, 18% exceeded age-10, and 1% were age-20 or older. Marginal increment analysis revealed that annuli formed concurrent with a protracted spawning season (April-July). The von Bertalanffy growth equation, derived from back-calculated mean lengths-at-age, was l(t) = 742 [1-e-0.085 (t-1.816)]. Tautog are long-lived (25+ yr) and attain relatively large sizes (672 mm TL) slowly (K for sexes combined = 0.085). Growth rates of both sexes are similar, although males grow slightly faster (K = 0.090 vs. 0.085 for females). Maturity occurs at age-3 in both sexes. Growth rates for tautog from Virginia are similar to those reported nearly 25 years ago for tautog in Rhode Island. Growth rates for tautog are similar to those of other reef fishes, such as snappers and groupers. Habitat restriction, slow growth, great longevity, and increasing popularity by user groups may contribute to over-exploitation of this species in Virginia waters.

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Phytoplankton Relationships To Water Quality In Lake Drummond And Two Drainage Ditches, Christine G. Phillips, Harold G. Marshall Jan 1993

Phytoplankton Relationships To Water Quality In Lake Drummond And Two Drainage Ditches, Christine G. Phillips, Harold G. Marshall

Biological Sciences Faculty Publications

A twelve-month phytoplankton study was conducted in Lake Drummond and Washington and Jericho Ditches from December 1988 to November 1989. Four dominant phytoplankton groups were identified at these sites. These were the Bacillariophyceae, Cyanophyceae, Cryptophyceae and an autotrophic picoplankton component. Over the past 20 years there has been a decrease in the mean pH levels of Lake Drummond and the replacement of one its former major components, the Chlorophyceae, by the Cyanophyceae. Based on water quality analysis results and species diversity indices, Lake Drummond is classified as in an early eutrophic stage of development.

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Seasonal Relationships Between Phytoplankton Composition, Abundance, And Primary Productivity In Three Tidal Rivers Of The Lower Chesapeake Bay, Harold G. Marshall, Kneeland K. Nesius Jan 1993

Seasonal Relationships Between Phytoplankton Composition, Abundance, And Primary Productivity In Three Tidal Rivers Of The Lower Chesapeake Bay, Harold G. Marshall, Kneeland K. Nesius

Biological Sciences Faculty Publications

The seasonal abundance and successional patterns of phytoplankton, including autotrophic picoplankton, are compared to spring, summer, and fall primary production maxima that occurred in three tidal rivers. The tidal freshwaters were dominated by diatoms, chlorophytes, and cyanobacteria during a late spring through early fall period of maximum growth. In contrast, downstream assemblages were dominated by estuarine diatoms, dinoflagellates, and cryptomonads which developed spring pulses and a protracted summer-fall maximum. Autotrophic picoplankton produced a major summer pulse at all river stations with reduced abundance during other seasons. The mean annual productivity rates for the tidal James, Rappahannock, and York rivers were …

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Microzooplankton In The Lower Chesapeake Bay, And The Tidal Elizabeth, James, And York Rivers, Gyung-Soo Park, Harold G. Marshall Jan 1993

Microzooplankton In The Lower Chesapeake Bay, And The Tidal Elizabeth, James, And York Rivers, Gyung-Soo Park, Harold G. Marshall

Biological Sciences Faculty Publications

Results of a one year study in the lower Chesapeake Bay and three tidal rivers indicate an abundant microzooplankton population, with a mean concentration of 4,231.1/Liter. The most abundant components are the non-loricate ciliates (2,518.2L, 59.5% of the annual total) and tintinnids (1,400.1/L 33.1%). In lesser abundance were the rotifers (191.4/L) and nauplii larvae (121.7/L). Seasonal abundance maxima were highest in summer, followed by fall, spring and winter.

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Gene Probe Analysis Of Soil Microbial Populations Selected By Amendment With 2,4-Dichlorophenoxyacetic Acid, William Holben, B. M. Schroeter, V. G.M. Calabrese, R. H. Olsen, J. K. Kukor, V. O. Biederbeck, James M. Tiedje Dec 1992

Gene Probe Analysis Of Soil Microbial Populations Selected By Amendment With 2,4-Dichlorophenoxyacetic Acid, William Holben, B. M. Schroeter, V. G.M. Calabrese, R. H. Olsen, J. K. Kukor, V. O. Biederbeck, James M. Tiedje

Biological Sciences Faculty Publications

Soils with a history of 2,4-dichlorophenoxyacetic acid (2,4-D) treatment at field application rates and control soils with no prior exposure to 2,4-D were amended with 2,4-D in the laboratory. Before and during these treatments, the populations of 2,4-D-degrading bacteria were monitored by most-probable-number (MPN) enumeration and hybridization analyses, using probes for the tfd genes of plasmid pJP4, which encode enzymes for 2,4-D degradation. Data obtained by these alternate methods were compared. Several months after the most recent field application of 2,4-D (approximately 1 ppm), soils with a 42-year history of 2,4-D treatment did not have significantly higher numbers of 2,4-D-degrading …

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Avian Forelimb Muscles And Nonsteady Flight: Can Birds Fly Without Using The Muscles In Their Wings?, Kenneth P. Dial Oct 1992

Avian Forelimb Muscles And Nonsteady Flight: Can Birds Fly Without Using The Muscles In Their Wings?, Kenneth P. Dial

Biological Sciences Faculty Publications

Intensity patterns of electromyographic (EMG) signals from selected muscles of the wing were studied during different modes of flight in trained Rock doves (Columba livia). Shoulder muscles exhibited a stereotypic pattern producing maximal EMG intensity during the deceleration phases of the upstroke and the downstroke, whereas the muscles of the brachium and antebrachium acted primarily as joint stabilizers during level flapping flight. During nonsteady flight (e.g. takeoff, landing, vertical ascending flight), the distal forelimb muscles exhibited maximal EMG intensity; their primary function appears to be associated with changing the camber and planform of the wing during rapid oscillation. During steady …

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Multiple Phosphate Positions In The Catalytic Site Of Glycogen Phosphorylase, Stephen R. Sprang, Neil B. Madsen, Stephen G. Withers Sep 1992

Multiple Phosphate Positions In The Catalytic Site Of Glycogen Phosphorylase, Stephen R. Sprang, Neil B. Madsen, Stephen G. Withers

Biological Sciences Faculty Publications

The three‐dimensional structure of an R‐state conformer of glycogen phosphorylase containing the coenzyme‐substrate analog pyridoxal‐5′‐diphosphate at the catalytic site (PLPP‐GPb) has been refined by X‐ray crystallography to a resolution of 2.87 Å. The molecule comprises four subunits of phosphorylase related by approximate 222 symmetry. Whereas the quaternary structure of R‐state PLPP‐GPb is similar to that of phosphorylase crystallized in the presence of ammonium sulfate (Barford, D. & Johnson, L.N., 1989, Nature 340, 609–616), the tertiary structures differ in that the two domains of the PLPP‐GPb subunits are rotated apart by 5° relative to the T‐state conformation. Global differences among the …

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Intermediates In The Constitutive And Regulated Secretory Pathways Released In Vitro From Semi-Intact Cells, Mark L. Grimes, Regis B. Kelly May 1992

Intermediates In The Constitutive And Regulated Secretory Pathways Released In Vitro From Semi-Intact Cells, Mark L. Grimes, Regis B. Kelly

Biological Sciences Faculty Publications

Regulated secretory cells have two pathways that transport secreted proteins from the Golgi complex to the cell surface. To identify carrier vesicles involved in regulated and constitutive secretion, PC12 pheochromocytoma cells were labeled with [35S]sulfate to identify markers for the two secretory pathways, then mechanically permeabilized and incubated in vitro. Small constitutive secretory vesicles, containing mostly sulfated proteoglycans, accumulated during an in vitro incubation with ATP. In the presence of GTP gamma S, the constitutive vesicles became significantly more dense, suggesting that a coated intermediate was stabilized. Larger immature regulated secretory granules, enriched in sulfated secretogranin II, also escaped from …

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Evaluating Habitat Suitability Using Relative Abundance And Fledging Success Of Red-Naped Sapsuckers, Bret W. Tobalske May 1992

Evaluating Habitat Suitability Using Relative Abundance And Fledging Success Of Red-Naped Sapsuckers, Bret W. Tobalske

Biological Sciences Faculty Publications

No abstract provided.

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The Structure Of Human Lymphotoxin (Tumor Necrosis Factor-Β) At 1.9-Å Resolution, Michael J. Eckt, Mark Ultsch, Ernst Rinderknecht, Abraham M. De Vos, Stephen R. Sprang Feb 1992

The Structure Of Human Lymphotoxin (Tumor Necrosis Factor-Β) At 1.9-Å Resolution, Michael J. Eckt, Mark Ultsch, Ernst Rinderknecht, Abraham M. De Vos, Stephen R. Sprang

Biological Sciences Faculty Publications

The three-dimensional structure of recombinant human lymphotoxin (residues 24-171 of the mature protein) has been determined by x-ray crystallography at 1.9-Å resolution (Rcryst = 0.215 for I > 3σ(I)). Phases were derived by molecular replacement using tumor necrosis factor (TNF-α) as a search model. Like TNF-α, lymphotoxin (LT) folds to form a "jellyroll" β-sheet sandwich. Three-fold related LT subunits form a trimer stabilized primarily by hydrophobic interactions. A cluster of 6 basic residues around the 3-fold axis may account for the acid lability of the trimer. Although the structural cores of TNF-α and LT are similar, insertions and …

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