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Biomedical subjects

R M Weiner

Publications and source records attributed to R M Weiner.

At least 37 records · Page 2Linked to original sources
PubMed1991

Changes in macromolecular synthesis of gypsy moth cell line IPLB-Ld652Y induced by Autographa californica nuclear polyhedrosis virus infection.

The aberrant replication of the Autographa californica multiple-enveloped nuclear polyhedrosis virus (AcMNPV) in the Lymantria dispar cell line IPLB-Ld652Y was used as a model system for the investigation of factors regulating baculovirus host specificity. A previous study of this system indicates that viral gene expression in infected cells is extremely attenuated and subsequently all cellular and viral protein synthesis is inhibited. In the present study, infection of IPLB-Ld652Y cells with AcMNPV photochemically inactivated in situ resulted in a rapid reduction in cell mitotic indices and cell growth, as well as inducing a series of distinct morphological changes in these cells. At the molecular level, infection with inactivated virus, followed by pulse labelling with [3H]thymidine, resulted in a rapid [0 to 2 h post-infection (p.i.)] and permanent inhibition of host cellular DNA synthesis. Assays of cellular DNA polymerases in isolated IPLB-Ld652Y nuclei confirmed the reduction in cellular DNA synthesis observed in intact cells and indicated an initial (0 to 2 h p.i.) reduction in the activity of aphidicolin-sensitive DNA polymerases. Activity of all cellular DNA polymerases was inhibited at later times p.i. Host cell protein synthesis was completely inhibited after 48 h p.i. Treatment of inactivated virus and virus-infected cells with various chemical and physical factors (i.e. pH and temperature) or lysosomotropic agents revealed that virus entry into cells and fusion of endocytic vesicles (containing virus) with lysosomes were essential for suppression of cellular macromolecular synthesis. The possible involvement of structural components of the AcMNPV virion in these effects is discussed.

Animals↗
PubMed1991

Hyphomonas spp., Shewanella spp., and Other Marine Bacteria Lack Heterogeneous (Ladderlike) Lipopolysaccharides.

The lipopolysaccharides (LPS) of 19 marine bacteria were examined for size heterogeneities by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis in conjunction with an LPS-specific silver staining method. Fifteen marine bacteria had an R-type LPS instead of the ladderlike LPS array characteristic of most bacteria. In addition, three marine bacteria also had a single large LPS molecule. Without constraints (e.g., surface masking), R-type LPS, a more hydrophobic molecule, predominates in Shewanella and Hyphomonas species and in other marine bacteria.

Journal Article↗
PubMed1990

Interactions between Shewanella colwelliana, Oyster Larvae, and Hydrophobic Organophosphate Pesticides.

Shewanella colwelliana (strain D) is a periphytic estuarine bacterium that forms biofilms beneficial to oyster set. Our study examined whether these and other films concentrated two hydrophobic, organophosphate pesticides, Abate and malathion, that are detected in Chesapeake Bay oyster waters. Both biofilms and purified exopolysaccharide of S. colwelliana did not adsorb more of the Abate or malathion than could be accounted for by adsorption to control surfaces. Similar results were obtained by using Deleya marina, Hyphomonas MHS3, and autochthonous biofilms. Conversely, decapsulated S. colwelliana D cells, prepared in the laboratory, bioconcentrated Abate. Significantly, the S. colwelliana D biofilms exposed to Abate did not inhibit the settlement and metamorphosis of Crassostrea gigas larvae.

Journal Article↗
PubMed1989

Major outer membrane proteins unique to reproductive cells of Hyphomonas jannaschiana.

Separation on the basis of molecular weight resolved three proteins specific to the swarmer cell of Hyphomonas jannaschiana. In the reproductive cell, 4 major proteins were identified as cytoplasmic and 10 were identified as envelope. Of these envelope proteins, one was common to both the inner and outer membranes, four were common to the inner membrane, and five were common to the outer membrane. Four of these outer membrane proteins were specific to the reproductive cell, and two of these proteins, with apparent molecular weights of 116,000 and 29,000, constituted 19% of the total cell protein and 54% of the outer membrane protein.

Bacterial Outer Membrane Proteins↗
PubMed1986

Semipermissive Replication of a Nuclear Polyhedrosis Virus of Autographa californica in a Gypsy Moth Cell Line.

Several gypsy moth cell lines have been previously described as nonpermissive for the multiple-embedded nuclear polyhedrosis virus of Autographa californica (AcMNPV). In this report, we demonstrate the semipermissive infection of a gypsy moth cell line, IPLB-LD-652Y, with AcMNPV. IPLB-LD-652Y cells infected with AcMNPV produced classic cytopathic effects but failed to yield infectious progeny virus. Results of experiments employing DNA-DNA dot hybridization suggested that AcMNPV DNA synthesis was initiated from 8 to 12 h postinfection (p.i.), continued at a maximum rate from 12 to 20 h p.i., and declined from 20 to 36 h p.i. The rate of AcMNPV DNA synthesis approximated that observed in the permissive TN-368 cell line. AcMNPV-infected IPLB-LD-652Y cells, pulse-labeled with [(35)S]methionine at various time intervals p.i. and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed four virus-induced proteins, one novel to the semipermissive system and three early alpha proteins, synthesized from 1 to 20 h p.i. Thereafter, both host and viral protein synthesis was completely suppressed. These results suggest that AcMNPV adsorbed, penetrated, and initiated limited macromolecular synthesis in the semipermissive gypsy moth cell line. However, the infection cycle was restricted during the early phase of AcMNPV replication.

Journal Article↗
PubMed1985

Characterization of a Marine Bacterium Associated with Crassostrea virginica (the Eastern Oyster).

A gram-negative bacterium found to be closely associated with oysters has been isolated and characterized. The organism, designated LST, has a generation time of 106 min in Marine broth under optimal growth conditions at 25 degrees C. During the decline phase of growth, it exhibits a morphological transition from a motile rod (ca. 1 mum in length) to an elongated, 3- to 40-mum, nonmotile, tightly coiled helix. LST synthesizes and releases a pigment in the stationary and decline phases of growth. Identified as melanin on the basis of chemical properties and UV absorbance maxima, the pigment comprises polymers of heterogeneous molecular weights, ranging from 12,000 to 120,000. The guanosine-plus-cytosine content of the LST DNA is 46%, and results of phenetic analysis and DNA-DNA hybridization indicate that this bacterium represents a new species. LST adheres to a variety of surfaces, including glass, plastics, and oyster shell, and has been shown to promote the settlement of oyster larvae.

Journal Article↗
PubMed1982

Rifampin inhibition of the occluded virus form of a nuclear polyhedrosis virus.

Rifampin at concentrations toxic to noninfected cells but not to infected cells is a selective inhibitor of occluded virus of the group A Baculoviridae (nuclear polyhedrosis virus). However, the titer of nonoccluded virus is not affected. Rifampin blocks occlusion until late in the replication cycle (14 to 16 h), and its effects are reversible. Modes of action of polyhedral inclusion body production are unknown.

Inclusion Bodies↗
PubMed1981

Bacteria associated with false-positive most-probable-number coliform test results for shellfish and estuaries.

Aerobic and facultatively anaerobic bacteria isolated from false-positive, presumptive, total coliform, most-probable-number tests of Chesapeake Bay oyster, water, and sediment samples were characterized and then classified by numerical taxonomy. A total of 538 bacterial strains clustered into 17 phena, the predominant groups of which were Enterobacteriaceae (including Escherichia coli), Aeromonas spp., and Bacillus spp. Bacillus spp. were recovered most frequently from sediment samples. Gas-producing strains which were not members of the Enterobacteriaceae were not isolated during this study. However, disproportionately large numbers of atypical and anaerogenic lactose-fermenting strains were encountered. We concluded that no single, specific bacterial group can be identified as being responsible for the false-positive reaction in the presumptive coliform test. Instead, the false-positive reaction is a result of complex interactions among various genera, representing predominantly bacteria other than coliforms.

Animals↗
PubMed1981

Physical Factors That Affect In Vitro Autographa californica Nuclear Polyhedrosis Virus Infection.

Of the physical parameters tested for in vitro baculovirus infection, multiplicity of infection was most important in governing percent cell infection. Most plaques formed within the first 5 min of incubation. Efficiency of infection, however, was low, and the virus titer did not diminish during prolonged incubation. Efficiency of infection improved markedly when cells or virus were preincubated with selected polyanions and polycations. Precise regulation of the pH, osmotic pressure, and ionic composition of the cell culture medium also promoted maximum in vivo infection.

Journal Article↗
PubMed1980

Timing of swarmer cell cycle morphogenesis and macromolecular synthesis by Hyphomicrobium neptunium in synchronous culture.

The swarmer cycle of Hyphomicrobium neptunium consists of a temporal sequence of discrete developmental events. To time morphogenesis and to investigate modulations in macromolecular synthesis, we attempted methods for synchronous culture. During synchrony, swarmer maturation occurred over 32%, hyphal growth occurred over 36%, and bud maturation occurred over 32% of the time required to complete the swarmer cycle. Daughter cells were released after 265 min. Deoxyribonucleic acid replication was discontinuous, having a G1 period of approximately 180 min. In addition, ribonucleic acid and protein syntheses were depressed during the earlier phases of development.

Bacteria↗
PubMed1980

Serological relationships among budding, prosthecate bacteria.

The somatic antigens of 25 strains of budding bacteria were typed and 14 serologically distinct groups were identified, suggesting considerable antigenic diversity among hyphomicrobia. Ten of the groups were represented by a single isolate, 2 contained two isolates, 1 three isolates, and 1 eight isolates. The strains in the largest group of eight isolates each shared at least one common antigen. However, there was also considerable antigenic heterogeneity within this cluster. Serological activity resided in the lipopolysaccharide (LPS) portion of cell walls and also in a heat labile component of Hyphomicrobium neptunium. The amino acid utilizing isolates, H. neptunium and Hyphomonas polymorpha, were serologically unrelated and it is suggested that the two organisms could be grouped as members of the same genus but not the same species.

Agglutination Tests↗
PubMed1980

An estuarine agar medium for enumeration of aerobic heterotrophic bacteria associated with water, sediment, and shellfish.

A plate count agar was formulated for use in bacteriological analysis of estuarine samples and was tested together with standard plate count agar and an estuarine salts yeast extract agar for growth of aerobic, heterotrophic bacteria in water, sediment, and oysters. The estuarine agar was found to be efficient for enumerating aerobic, heterotrophic bacterial populations of water, sediment, and oysters, and is recommended for plate counts of estuarine samples.

Agar↗
PubMed1979

Microbial impact of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus) on aquatic ecosystems.

Quantitative and qualitative analyses of the intestinal bacterial flora of Canada geese and whistling swans were carried out with the finding that wild birds harbor significantly more fecal coliforms than fecal streptococci. The reverse was typical of captive and fasting birds. Neither Salmonella spp. nor Shigella spp. were isolated from 44 migratory waterfowl that were wintering in the Chesapeake Bay region. Enteropathogenic Escherichia coli were detected in seven birds. Geese eliminated 10(7) and swans 10(9) fecal coliforms per day. Results of in situ studies showed that large flocks of waterfowl can cause elevated fecal coliform densities in the water column. From the data obtained in this study, it is possible to predict the microbial impact of migratory waterfowl upon aquatic roosting sites.

Animals↗
PubMed1979

Development of Defined, Minimal, and Complete Media for the Growth of Hyphomicrobium neptunium.

A complete synthetic medium containing 15 amino acids, a minimal synthetic medium (GAMS) containing 4 amino acids, and a supplemented minimal medium (GAMS + calcium pantothenate) have been developed for the cultivation of Hyphomicrobium neptunium ATCC 15444. Depending on the complexity of the synthetic media, generation times were approximately 2 to 3 times longer, and maximum cell densities were 0.3 to 0.9 log(10) lower than in ZoBell marine broth 2216. The fates of C-labeled amino acids in GAMS were monitored. Results suggested that H. neptunium was auxotrophic for methionine, utilized glutamic acid as a primary energy source, and readily anabolized and catabolized serine and aspartic acid. Individual amino acid concentrations above 125 mM induced prolonged lag periods, whereas only methionine was not growth limiting at a concentration as low as 2 mM.

Journal Article↗
PubMed1979

Aerobic and facultatively anaerobic bacteria associated with the gut of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus).

Aerobic and facultatively anaerobic bacteria from the intestinal tracts of swans and geese were isolated and characterized as part of a larger study of the microbiological effects of migratory waterfowl on water quality. A total of 356 isolates were identified by using rapid identification methods and classified by using numerical taxonomy. A diverse population of bacteria was recovered from the waterfowl, and representative strains could be classified into 21 phena. The majority of the aerobic, heterotrophic bacteria found in the gut of the waterfowl were species of Enterobacteriaceae. Streptococcus. Lactobacillus, and Bacillus. Unfortunately, the birds that were examined did not harbor significant numbers of any waterfowl-specific bacterial species. Thus, it may not be possible to assess microbiological impact of migratory waterfowl by using and "indicator" species since avian fecal pollution could not be distinguished from animal and human fecal pollution.

Aerobiosis↗