Phylogenetic differences between particle-associated and planktonic ammonia-oxidizing bacteria of the beta subdivision of the class Proteobacteria in the Northwestern Mediterranean Sea

The aim of this study was to determine if there were differences between the types of ammonia-oxidizing bacteria of the beta subdivision of the class Proteobacteria associated with particulate material and planktonic samples obtained from the northwestern Mediterranean Sea. A nested PCR procedure performed with ammonia oxidizer-selective primers was used to amplify 16S rRNA genes from extracted DNA. The results of partial and full-length sequence analyses of 16S rRNA genes suggested that different groups of ammonia-oxidizing bacteria were associated with the two sample types. The particle-associated sequences were predominantly related to Nitrosomonas eutropha, while the sequences obtained from the planktonic samples were related to a novel marine Nitrosospira group (cluster 1) for which there is no cultured representative yet. A number of oligonucleotide probes specific for different groups of ammonia oxidizers were used to estimate the relative abundance of sequence types in samples of clone libraries. The planktonic libraries contained lower proportions of ammonia oxidizer clones (0 to 26%) than the particulate material libraries (9 to 83%). Samples of the planktonic and particle-associated libraries showed that there were depth-related differences in the ammonia oxidizer populations, with the highest number of positive clones in the particle-associated sample occurring at a depth of 700 m. The greatest difference between planktonic and particle-associated populations occurred at a depth of 400 m, where only 4% of the clones in the planktonic library were identified as Nitrosomonas clones, while 96% of these clones were identified as clones that were related to the marine Nitrosospira species. Conversely, all ammonia oxidizer-positive clones obtained from the particle-associated library were members of the Nitrosomonas group. This is the first indication that Nitrosomonas species and Nitrosospira species may occupy at least two distinct environmental niches in marine environments. The occurrence of these groups in different niches may result from differences in physiological properties and, coupled with the different environmental conditions associated with these niches, may lead to significant differences in the nature and rates of nitrogen cycling in these environments.     

Algicidal effects of a novel marine pseudoalteromonas isolate (class Proteobacteria, gamma subdivision) on harmful algal bloom species of the genera Chattonella, Gymnodinium, and Heterosigma

During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species. This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin. This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo). It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h. Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans. The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating. Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects. The minimum concentrations of strain Y required to kill G. catenatum were higher than the mean concentrations found in nature under nonbloom conditions. However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms. These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms.     

Interpersonal dominance of Type As in group discussions.

Two types of dominant behavior—the frequency of pro-self arguments and of anti-other arguments—were naturalistically observed in random groups of 5 or 6 male undergraduates (N?=?28) discussing 1 of 3 topics for 15 min. Although there was a marginal tendency for Type A (coronary prone) Ss (classified under the Jenkins Activity Survey) to exhibit more pro-self arguments, semipartial correlations revealed that this variable had negligible effect in predicting Ss' Type A scores when compared with anti-other arguments. Results are consistent with the hypothesis that Type A individuals are interpersonally dominant and suggest that one reason for their heightened competitiveness may be the control and dominance of others, rather than material gains. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The socialization of dominance: Peer group contextual effects on homophobic and dominance attitudes.

Using the framework of social dominance theory, the current investigation tested for the contextual effects of adolescent peer groups on individuals' homophobic and social dominance attitudes. Results from multilevel models indicated that significant differences existed across peer groups on homophobic attitudes. In addition, these differences were accounted for on the basis of the hierarchy-enhancing or -attenuating climate of the group. A group socialization effect on individuals' social dominance attitudes over time was also observed. Furthermore, the social climate of the peer group moderated the stability of individuals' social dominance attitudes. Findings support the need to examine more proximal and informal group affiliations and earlier developmental periods in efforts to build more comprehensive theoretical models explaining when and how prejudiced and dominance attitudes are formed and the way in which they are perpetuated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Korormicin, a novel antibiotic specifically active against marine gram-negative bacteria, produced by a marine bacterium

A novel antibiotic named korormicin was isolated from the marine bacterium, Pseudoalteromonas sp. F-420. This strain was isolated from the surface of a macro alga Halimeda sp. collected from Palau (the Republic of Belau). The planar structure of korormicin was determined by the result of 2D NMR studies and mass spectral data. Korormicin had specific inhibitory activity against marine Gram-negative bacteria, but was inactive against terrestrial microorganisms.     

Effects of dominance on group decision making: Toward a stress-reduction explanation of groupthink.

Investigated the effects of procedural guidelines for decision making and a personality trait (dominance) on state anxiety and decision quality. 112 undergraduate students who served as Ss were administered the EPPS to determine high or low dominance. Ss participated in 28 4-person, mixed-sex groups and were audiorecorded while they completed a group decision-making task. Results indicate that groups composed of highly dominant members made higher quality decisions, exhibited lower state anxiety, and took more time to reach a decision. They also tended to make more statements of disagreement and agreement and to report more group influence on the members. Results provide support for a stress-reduction explanation of I. L. Janis's (1972) "groupthink" hypothesis with respect to groups composed of either high- or low-dominance individuals. Despite the support of the groupthink hypothesis with respect to dominance, the manipulation of decision-making procedures affected only decision time. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Degradation of hydrocarbons in the presence of other organic substances by bacteria isolated from seawater

Three bacterial strains, isolated on gas-oil from seawater, have a variously changed growth on hexadecane with supply of two organic substances. Acetate reduces growth of all tested strains and particularly the hexadecane degradation by Acinetobacter sp. On the contrary, trypticase-phytone promotes the degradation by the three strains.     

The sea to air bacteria transfer from the coastal waters

Bacteria transfer from the water into the air may play an important role in bioaerosol cycle. Bubbles raising through the water column collect bacteria but also other suspended material and transport them towards water surface. When the bubble burst at the water surface collected material are skimmed off the bubble to become highly enriched in jet and film drops. After ejection airborne droplets can evaporate and as small droplets can be transported even to remote locations. Such a stream of aerosol droplets may carry stream of bacteria scavenged from the water column. The fate of bacteria in the air may possibly depend on the environmental conditions like intensity of sunlight or ambient air humidity. In addition the wind speed might be responsible for both wave/bubble mediated production of marine originated droplets and their transport in the atmosphere. The evidences that bacteria are transferred from the breaking waves, in particular in the coastal zone, were observed during several field experiments conducted in 1994 and 1995 over the Gulf of Gdansk and the Baltic Sea coast. Enhanced sea to air bacteria transfer were noticed over the polluted waters where in addition gas supersaturations in the water were recorded. Further laboratory investigations of bacteria scavenge via bubbles produced by single capillary and by plume of bubbles produced by ceramic stone indicated high enrichment within both mesophile and psychrophile bacteria categories.     

Patterns of family conflict and dominance as a function of child age and social class.

Systematically evaluated 44 family triads, consisting of middle- or lower-class families with 11- or 16-yr-old sons, by direct observation procedures. When dominance and conflict patterns were assessed by process measures (talking time, attempted interruptions, successful interruptions) and by outcome measures (unrevealed difference technique), both social class and age of child were significantly associated with many of the selected interaction indexes. Results indicated that the adolescent accrues influence at the expense of the mother in middle-class families, whereas the adolescent's gain in influence is often at the expense of the father in lower-class families. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isolation of broad-host-range replicons from marine sediment bacteria

Naturally occurring plasmids isolated from heterotrophic bacterial isolates originating from coastal California marine sediments were characterized by analyzing their incompatibility and replication properties. Previously, we reported on the lack of DNA homology between plasmids from the culturable bacterial population of marine sediments and the replicon probes specific for a number of well-characterized incompatibility and replication groups (P. A. Sobecky, T. J. Mincer, M. C. Chang, and D. R. Helinski, Appl. Environ. Microbiol. 63:888-895, 1997). In the present study we isolated 1.8- to 2.3-kb fragments that contain functional replication origins from one relatively large (30-kb) and three small (<10-kb) naturally occurring plasmids present in different marine isolates. 16S rRNA sequence analyses indicated that the four plasmid-bearing marine isolates belonged to the alpha and gamma subclasses of the class Proteobacteria. Three of the marine sediment isolates are related to the gamma-3 subclass organisms Vibrio splendidus and Vibrio fischeri, while the fourth isolate may be related to Roseobacter litoralis. Sequence analysis of the plasmid replication regions revealed the presence of features common to replication origins of well-characterized plasmids from clinical bacterial isolates, suggesting that there may be similar mechanisms for plasmid replication initiation in the indigenous plasmids of gram-negative marine sediment bacteria. In addition to replication in Escherichia coli DH5alpha and C2110, the host ranges of the plasmid replicons, designated repSD41, repSD121, repSD164, and repSD172, extended to marine species belonging to the genera Achromobacter, Pseudomonas, Serratia, and Vibrio. While sequence analysis of repSD41 and repSD121 revealed considerable stretches of homology between the two fragments, these regions do not display incompatibility properties against each other. The replication origin repSD41 was detected in 5% of the culturable plasmid-bearing marine sediment bacterial isolates, whereas the replication origins repSD164 and repSD172 were not detected in any plasmid-bearing bacteria other than the parental isolates. Microbial community DNA extracted from samples collected in November 1995 and June 1997 and amplified by PCR yielded positive signals when they were hybridized with probes specific for repSD41 and repSD172 replication sequences. In contrast, replication sequences specific for repSD164 were not detected in the DNA extracted from marine sediment microbial communities.     

Divergence in nitrogenases of Azoarcus spp., Proteobacteria of the beta subclass

Nitrogenase is a functionally constant protein catalyzing N2 reduction, which is found in many phylogenetic lineages of Archaea and Bacteria. A phylogenetic analysis of nif genes may provide insights into the evolution of the bacterial genomes. Moreover, it may be used to study diazotrophic communities, when classical isolation techniques may fail to detect all contributing populations. Among six species of the genus Azoarcus, diazotrophic Proteobacteria of the beta subclass, the deduced amino acid sequences of nifH genes of two species were unusually divergent from each other. Nitrogenases of the "authentic" Azoarcus branch formed a monophyletic unit with those of gamma Proteobacteria, thus being in accordance with 16S ribosomal DNA phylogeny. The nitrogenase proteins of the two aberrant strains clustered within the alpha proteobacterial clade with rhizobial nitrogenases. This relationship was supported by bootstrap values of 87 to 98% obtained by various distance and maximum parsimony methods. Phylogenetic distances of NifH proteins indicate a possible lateral gene transfer of nif genes to Azoarcus from a common donor of the alpha subclass at the time of species diversification or several more recent, independent transfers. Application of the phylogenetic analysis to DNA isolated from environmental samples demonstrated novel habitats for Azoarcus: in guts of termites and rice grown in Japan, nifH genes belonging to the authentic Azoarcus branch were detected. This is the first evidence suggesting the occurrence of Azoarcus spp. in a plant other than its originally described host, Kallar grass. Moreover, evidence for expression of nif genes inside grass roots was obtained by in situ hybridization studies with antisense nifH probes.     

辽宁沿海经济带海洋环境保护法律问题研究

通过对辽宁沿海经济带海洋环现状的调查,指出辽宁省沿海经济带海洋环境保护存在缺乏配套细则、主管部门职权分割严重等问题,提出完善法律法规的配套、促进公众参与机制建立、完善诉讼救济等具体解决建议.     

Degradation of weathered oil by mixed marine bacteria and the toxicity of accumulated water-soluble material to two marine crustacea

From 1982 to 1984, the authors conducted a population-based case-control study of lung cancer in men and women nonsmokers in New York State. In-person interviews were completed for 437 lung cancer cases (197 never smokers, 240 former smokers) and 437 matched population controls. Cases and controls were asked to report any history of physician-diagnosed nonmalignant lung disease; cases were more likely than controls to report such a history. Statistically significant associations were found for emphysema (odds ratio (OR) = 1.94, 95% confidence interval (CI) 1.10-3.43), chronic bronchitis (OR = 1.73, 95% CI 1.10-2.72), and the combined endpoint of emphysema, chronic bronchitis, or asthma (OR = 1.82, 95% CI 1.26-2.63). After adjustment for active and passive tobacco smoke exposure, emphysema, chronic bronchitis, and asthma (each condition and the combined endpoint) were significantly associated with lung cancer risk. The risk was more marked for squamous cell carcinomas and for subjects who were diagnosed at older ages, and it remained significant when surrogate interviews were excluded. These results are consistent with the hypothesis that certain prior lung conditions increase the risk of lung cancer in men and women nonsmokers.     

Genome evolution within the alpha Proteobacteria: why do some bacteria not possess plasmids and others exhibit more than one different chromosome?

Animal intracellular Proteobacteria of the alpha subclass without plasmids and containing one or more chromosomes are phylogenetically entwined with opportunistic, plant-associated, chemoautotrophic and photosynthetic alpha Proteobacteria possessing one or more chromosomes and plasmids. Local variations in open environments, such as soil, water, manure, gut systems and the external surfaces of plants and animals, may have selected alpha Proteobacteria with extensive metabolic alternatives, broad genetic diversity, and more flexible and larger genomes with ability for horizontal gene flux. On the contrary, the constant and isolated animal cellular milieu selected heterotrophic alpha Proteobacteria with smaller genomes without plasmids and reduced genetic diversity as compared to their plant-associated and phototrophic relatives. The characteristics and genome sizes in the extant species suggest that a second chromosome could have evolved from megaplasmids which acquired housekeeping genes. Consequently, the genomes of the animal cell-associated Proteobacteria evolved through reductions of the larger genomes of chemoautotrophic ancestors and became rich in adenosine and thymidine, as compared to the genomes of their ancestors. Genome organisation and phylogenetic ancestor-descendent relationships between extant bacteria of closely related genera and within the same monophyletic genus and species suggest that some strains have undergone transition from two chromosomes to a single replicon. It is proposed that as long as the essential information is correctly expressed, the presence of one or more chromosomes within the same genus or species is the result of contingency. Genetic drift in clonal bacteria, such as animal cell-associated alpha Proteobacteria, would depend almost exclusively on mutation and internal genetic rearrangement processes. Alternatively, genomic variations in reticulate bacteria, such as many intestinal and plant cell-associated Proteobacteria, will depend not only on these processes, but also on their genetic interactions with other bacterial strains. Common pathogenic domains necessary for the invasion and survival in association with cells have been preserved in the chromosomes of the animal and plant-associated alpha Proteobacteria. These pathogenic domains have been maintained by vertical inherence, extensively ameliorated to match the chromosome G + C content and evolved within chromosomes of alpha Proteobacteria.     

Stress and dominance in a social fish

Many aspects of reproductive physiology are subject to regulation by social interactions. These include changes in neural and physiological substrates of reproduction. How can social behavior produce such changes? In experiments reported here, we manipulated the social settings of teleost fish and measured the effect (1) on stress response as reflected in cortisol production, (2) on reproductive potential as measured in production of the signaling peptide, gonadotropin-releasing hormone, and (3) on reproductive function measured in gonad size. Our results reveal that the level of the stress hormone cortisol depends critically on both the social and reproductive status of an individual fish and on the stability of its social situation. Moreover, the reproductive capacity of an individual fish depends on these same variables. These results show that social encounters within particular social contexts have a profound effect on the stress levels as well as on reproductive competence. Social behavior may lead to changes in reproductive state through integration of cortisol changes in time. Thus, information available from the stress pathway may provide socially relevant signals to produce neural change.     

Specific acyclic isoprenoids as biological markers of methanogenic bacteria in marine sediments

The widespread occurrence of extended hopanoids in sediments and petroleums illustrates the importance of bacterial lipid contributions to geological materials. In archaebacteria, however, hopanoids are absent; their role as structural components of biomembranes is fulfilled by acyclic isoprenoids. Recent studies of the lipid constituents of archaebacteria have greatly extended the range of acyclic isoprenoid skeletons known in organisms (Fig. 1). In particularly, isoprenoids with head-to-head linkages have been identified, and such compounds (for example, 3,7,11,15,18,22,26,30-octamethyldotriacontane, I) have been recognized in petroleum and as degradation products of Messel shale kerogen. Here we report the first recognition of 2,6,10,15,19-pentamethyleicosane (II), a known component of methanogens, in marine sediments of Recent to Cretaceous age (Table 1) and suggest that it and certain other acyclic isoprenoids may be used as biological markers for methanogens.