Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean samples.

Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 microgram of one of a set of chemicals selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmid DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.     

Molecular characterization of a rotaviruslike virus isolated from striped bass (Morone saxatilis).

The characteristics of a rotaviruslike (SBR) virus isolated from striped bass (Morone saxatilis) were examined following purification of viruses from infected cell cultures. Virions had a double-layered capsid of icosahedral symmetry and a diameter of 75 nm. Purified viruses contained five polypeptides ranging in molecular mass from 130 to 35 kDa. None of the structural proteins were glycosylated. Treatment with EDTA did not remove the outer capsid. By using enzymes and a chaotropic agent, it was shown that VP5 was the most external polypeptide. The genome of SBR virus was composed of 11 segments of double-stranded RNA (dsRNA). The electrophoretic pattern of the dsRNA of SBR virus was different from that of reovirus type 1 (Lang) and rotavirus (SA11) dsRNA. The SBR virus was compared with reovirus type 1 and SA11 virus by RNA-RNA blot hybridization. There was no cross-hybridization between any of the genome segments of the SBR, reovirus type 1, or SA11 viruses. Antigenic comparison of SBR virus and SA11 virus by cross-immunoprecipitation and cross-immunofluorescence tests did not show any relationship. These results suggest that SBR virus could represent a new genus within the family Reoviridae.     

Molecular genetic and phenotypic alteration of Escherichia coli in natural water microcosms containing toxic chemicals

Abstract Microcosms of sterile Chesapeake Bay water were used to study effects of sub-lethal concentrations (1 μl/l) of nitrobenzene, m -cresol, and dibutyl phthalate on Escherichia coli H10407. E. coli remained viable during the 19-day test period in estuarine water, both in the presence and absence of the chemicals, long after it became non-culturable. Analysis of membrane proteins revealed changes in the protein composition. Carbohydrate and amino acid utilization was affected by these changes. Plasmids in E. coli H10407 could not be detected following microcosm exposure. When the cells were transferred to rich medium without toxic chemicals, growth resumed and plasmid bands were again detectable.     

α-Thalassemia among sickle cell anemia patients in various African populations

Summary We have studied the incidence of -thalassemia in normal and SS individuals from Senegal, Benin, Upper Volta, and Central Republican Africa. The thal gene frequency is not significantly different in the controls from the various populations and in the SS patients from Senegal. In contrast it is compatible with increased survival of SS patients in Benin, Upper Volta. The data suggest epistatic effects of other factors in the Senegalese population.     

Evolution and functional characterization of the RH50 gene from the ammonia-oxidizing bacterium Nitrosomonas europaea

The family of ammonia and ammonium channel proteins comprises the Amt proteins, which are present in all three domains of life with the notable exception of vertebrates, and the homologous Rh proteins (Rh50 and Rh30) that have been described thus far only in eukaryotes. The existence of an RH50 gene in bacteria was first revealed by the genome sequencing of the ammonia-oxidizing bacterium Nitrosomonas europaea. Here we have used a phylogenetic approach to study the evolution of the N. europaea RH50 gene, and we show that this gene, probably as a component of an integron cassette, has been transferred to the N. europaea genome by horizontal gene transfer. In addition, by functionally characterizing the Rh50_Ne protein and the corresponding knockout mutant, we determined that NeRh50 can mediate ammonium uptake. The RH50_Ne gene may thus have replaced functionally the AMT gene, which is missing in the genome of N. europaea and may be regarded as a case of nonorthologous gene displacement.     

Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean samples

Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 microgram of one of a set of chemicals selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmid DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.     

Bacterial detoxification of diisopropyl fluorophosphate

The ability of 18 gram-negative bacterial isolates to detoxify diisopropyl fluorophosphate, a structural analog of the agents soman and sarin, was investigated. Detoxification by both frozen cell sonicates and acetone powders was assayed by two methods, i.e., the hydrolytic release of fluoride, measured by a fluoride-specific ion electrode, and the disappearance of acetylcholinesterase inhibition in vitro. Frozen cell sonicates for all strains exhibited some activity (F- ion release). In general, acetone powder preparations produced higher activity than frozen cell sonicates did, and the highest activities were exhibited by strains with known parathion hydrolase activity. Two ranges in activity were observed, low level, ranging from 0.1 to 7.0 mumol/min per g of protein, and high level, detected only in parathion hydrolase-producing strains, from 47 to greater than 300 mumol/min per g of protein. Results indicate that parathion hydrolase was nonspecific in phosphoesterase activity. Also, it was an effective detoxicant at low concentrations and near-neutral pH.     

The size at reproduction of canopy tree species in central Africa

Size at reproduction is a key aspect of species life history that is relatively understudied for long‐lived tropical trees. Here, we quantified reproductive diameter for 31 major timber species across 11 sites in Cameroon, Congo, and Central African Republic. Specifically, we examined whether (1) between‐species variability is correlated with other species traits; (2) reproductive diameter varies within‐species among sites; (3) reproductive status varies with crown exposure; and (4) the minimum cutting diameter limits (MCDL) imposed by national forest regulations enable seed trees to persist after logging operations. Consistent with studies conducted elsewhere in the tropics, we found great variability in diameter at reproduction among species, which correlated with adult stature (maximum diameter and height). For some species, reproductive diameter thresholds substantially varied between sites, and crown exposure had a significant positive effect on reproductive status. Most MCDLs were found to be suitable, with trees having a high probability of being seed trees at MCDL. Our findings have implications for the sustainable management of production forests, and they highlight questionable MCDLs for some species and between‐site variation in reproductive diameter. The study also highlights the need for long‐term phenological monitoring of tree species spanning a large range of ecological strategies to address both theoretical (species life history, allocation trade‐offs) and practical questions (MCDL).     

Synthesis, characterization and electrochemical behavior of oxo-bridged (arylimido)[tris(3,5-dimethylpyrazolyl)borato] molybdenum(V) complexes

Reaction of the oxo-molybdenum(V) precursor [MoTp*(O)Cl₂] [Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate] with H₂NC₆H₄R-4 (R = OEt; OPr) in refluxing toluene in the presence of Et₃N afforded the binuclear oxo-bridged oxo(arylimido) molybdenum(V) complexes [Tp*Mo(O)Cl](μ-O)[Tp*Mo(NC₆H₄OR-4)Cl]. Surprisingly, a similar reaction between [MoTp*(O)Cl₂] and C₆H₅NH₂ yielded the previously reported compound [{MoTp*(O)Cl}₂(μ-O)] as the only product. The new compounds were characterized by microanalytical data, mass spectrometry, IR and ¹H NMR spectroscopy. Cyclic voltammetric studies of the new compounds, of the previously reported compounds [Tp*Mo(O)Cl](μ-O)[Tp*Mo(NAr)Cl] (Ar = C₆H₄OMe-4, C₆H₄F-3, C₆H₄Cl-4, C₆H₄Br-4, and C₆H₄I-3), and of [{MoTp*(O)Cl}₂(μ-O)] revealed a reversible one-electron oxidation process that is little affected by the nature of the substituent on the aryl group, whereas it is greatly affected by replacement of the imido ligand with an oxo ligand. The [{MoTp*(O)Cl}₂(μ-O)] compound also shows a one-electron reduction process.