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We examined the response of microbial communities in the model sea anemone Exaiptasia diaphana (Aiptasia) to short-term thermal elevation. Through 16S rRNA gene sequencing, we characterized the microbiomes of symbiotic (with algal symbionts) and aposymbiotic (bleached) anemones under ambient (27°C) and heat-stressed (34°C) conditions for 8-10 days, using both replicated endpoint and non-replicated time-course approaches. Consistent with prior studies, we observed a stable abundance of bacteria from the families Alteromonadaceae and Rhodobacteraceae, though with wide variation among individual anemones. We observed that symbiotic state conferred a larger impact on the microbiome than heat stress, implying the microbiome may play a metabolic role in the maintenance of cnidarian-dinoflagellate symbiosis. In particular, Pelobacter , an anaerobic sulfate reducer that is also a potential nitrogen fixer, was present only in symbiotic anemones, and its abundance decreased with initial exposure to 34°C, but recovered after 7 days. In aposymbiotic anemones, the added heat stress appeared to result in a large increase of rare bacterial taxa, which included potential pathogens such as Vibrio following bleaching. We also observed several archaea, the first reported for this model, but only in the seawater surrounding aposymbiotic Aiptasia, where abundance increased dramatically following heat stress. We further explored the diazotrophic (nitrogen fixation) potential of diverse bacteria associated with symbiotic and aposymbiotic Aiptasia, under both ambient and heat-stressed conditions, using nifH -PCR and qPCR and the acetylene reduction assay (ARA). In contrast to some stony corals, nifH was barely expressed in both anemone types, and under ambient conditions, diazotrophic activity was not detectable via ARA. Thus, although this research contributes to the growing knowledge of the bacterial community associated with a prominent model used in coral-symbiosis research, our results also suggest using caution when making direct comparisons between Aiptasia and different coral species in microbiome studies.

The activities of unicellular microbes dominate the ecology of the marine environment, but the chemical signals that determine behavioral interactions are poorly known. In particular, chemical signals between microbial predators and prey contribute to food selection or avoidance and to defense, factors that probably affect trophic structure and such large-scale features as algal blooms. Using defense as an example, I consider physical constraints on the transmission of chemical information, and strategies and mechanisms that microbes might use to send chemical signals. Chemical signals in a low Re, viscosity-dominated physical environment are transferred by molecular diffusion and laminar advection, and may be perceived at nanomolar levels or lower. Events that occur on small temporal and physical scales in the \"near-field\" of prey are likely to play a role in cell-cell interactions. On the basis of cost-benefit optimization and the need for rapid activation, I suggest that microbial defense system strategies might be highly dynamic. These strategies include compartmented and activated reactions, utilizing both pulsed release of dissolved signals and contact-activated signals at the cell surface. Bioluminescence and extrusome discharge are two visible manifestations of rapidly activated microbial defenses that may serve as models for other chemical reactions as yet undetected due to the technical problems of measuring transient chemical gradients around single cells. As an example, I detail an algal dimethylsulfoniopropionate (DMSP) cleavage reaction that appears to deter protozoan feeding and explore it as a possible model for a rapidly activated, short-range chemical defense system. Although the exploration of chemical interactions among planktonic microbes is in its infancy, ecological models from macroorganisms provide useful hints of the complexity likely to be found.

Marine plankton use a variety of defences against predators, some of which affect trophic structure and biogeochemistry. We have previously shown that, during grazing by the protozoan Oxyrrhis marina on the alga Emiliania huxleyi, dimethylsulphoniopropionate (DMSP) from the prey is converted to dimethyl sulphide (DMS) when lysis of ingested prey cells initiates mixing of algal DMSP and the enzyme DMSP lyase. Such a mechanism is similar to macrophyte defence reactions,. Here we show that this reaction deters protozoan herbivores, presumably through the production of highly concentrated acrylate, which has antimicrobial activity. Protozoan predators differ in their ability to ingest and survive on prey with high-activity DMSP lyase, but all grazers preferentially select strains with low enzyme activity when offered prey mixtures. This defence system involves investment in a chemical precursor, DMSP, which is not self-toxic and has other useful metabolic functions. We believe this is the first report of grazing-activated chemical defence in unicellular microorganisms.

Barbara Easton – Vice President of the British Methodist Church and Lead of the Methodist Academies and Schools Trust (MAST) The Methodist Academies & Schools Trust (Great Britain) The Rev Dr Mary Kinoti – Deputy Vice Chancellor Academic at Kenya Methodist University (Nairobi, Kenya) The Rev Dr Naveen Rao – Principal of Leonard Theological College (Jabalpur, India) The Rev Dr Thomas V. Wolfe – President & CEO, Iliff School of Theology (Denver, USA) In preparing this summary of the discussion of these panelists, one word keeps coming to mind. The overarching issue within the state and private school discussion is best described as a competition having to do with the identity and purpose of the curriculum. The tension exists between those who may impose a judgment on a portion of the curriculum that challenges their own knowledge and the faculty and administrators who seek to uphold academic freedom. The current Methodist educational mission has limited or no resources. Because of cost, students prefer government schools over Methodist schools.

Emiliania huxleyi clones CCMP 370 and CCMP 373 produced similar amounts of dimethylsulfoniopropionate (DMSP) during axenic exponential growth, averaging 109 mM internal DMSP. Both clones had detectable DMSP lyase activity, as measured by production of dimethyl sulfide (DMS) during in vitro assays of crude cell preparations, but activities and conditions differed considerably between clones. Clone 373 had high activity; clone 370 had low activity and required chloride. For both strains, enzyme activity per cell was constant during exponential growth, but little DMS was produced by healthy cells. Rather, DMS production was activated when cells were subjected to physical or chemical stresses that caused cell lysis. We propose that DMSP lyase and DMSP are segregated within these cells and reaction only under conditions that result in cell stress or damage. Such activation occurs during microzooplankton grazing. When these clones were grazed by the dinoflagellate Oxyrrhis marina, DMS was produced; ungrazed cells, as well as those exposed to grazer exudates and associated bacteria, generated no DMS. Grazing of clone 373 produced much more DMS than grazing of clone 370, consistent with their relative in vitro DMSP lyase activities. DMS was only generated when cells were actually being grazed, indicating that ingested cells were responsible for the DMS formation. We suggest that even low levels of grazing can greatly accelerate DMS production.

Systemic acquired resistance (SAR) is an inducible systemic plant defense against a broad spectrum of plant pathogens, with the potential to secrete antimicrobial compounds into the soil. However, its impact on rhizosphere bacteria is not known. In this study, we examined fingerprints of bacterial communities in the rhizosphere of the model plant Arabidopsis thaliana to determine the effect of SAR on bacterial community structure and diversity. We compared Arabidopsis mutants that are constitutive and non-inducible for SAR and verified SAR activation by measuring pathogenesis-related protein activity via a β-glucoronidase (GUS) reporter construct driven by the β-1-3 glucanase promoter. We used terminal restriction fragment length polymorphism (T-RFLP) analysis of MspI- and HaeIII-digested 16S rDNA to estimate bacterial rhizosphere community diversity, with Lactobacillus sp. added as internal controls. T-RFLP analysis showed a clear rhizosphere effect on community structure, and diversity analysis of both rhizosphere and bulk soil operational taxonomic units (as defined by terminal restriction fragments) using richness, Shannon-Weiner, and Simpson's diversity indices and evenness confirmed that the presence of Arabidopsis roots significantly altered bacterial communities. This effect of altered soil microbial community structure by plants was also seen upon multivariate cluster analysis of the terminal restriction fragments. We also found visible differences in the rhizosphere community fingerprints of different Arabidopsis SAR mutants; however, there was no clear decrease of rhizosphere diversity because of constitutive SAR expression. Our study suggests that SAR can alter rhizosphere bacterial communities, opening the door to further understanding and application of inducible plant defense as a driving force in structuring soil bacterial assemblages.

Activated defenses against herbivores and predators are defenses whereby a precursor compound is stored in an inactive or mildly active form. Upon damage to the prey, the precursor is enzymatically converted to a more potent toxin or feeding deterrent. In marine systems, activated defenses are only known to exist in a few species of tropical macroalgae. In this study, we examined an activated defense system in temperate marine macroalgae in which the osmolyte dimethylsulfoniopropionate (DMSP) is converted to acrylic acid or acrylate, depending upon the pH, and dimethyl sulfide (DMS) by the enzyme DMSP lyase upon damage to the alga. We surveyed 39 species of red, green, and brown algae from the Washington and Oregon coasts, and found high concentrations of DMSP in the chlorophytesAcrosiphonia coalita, Codium fragile, Enteromorpha intestinalis, E. linza, Ulva californica, U. fenestrata, andU. taeniata, and in the rhodophytePolysiphonia hendryi. Concentrations of DMSP ranged from 0.04% of the alga’s fresh mass (FM) to 1.8% FM. We found significant DMSP lyase activity in 1 green alga,U. fenestrata, and 1 red alga,P. hendryi, with DMSP cleavage rates approaching 300 mmol kg–1FM min–1. Loss of DMSP and the production of DMS when the tissues ofU. californicaandP. hendryiwere crushed suggested that physical damage results in DMSP cleavage. In laboratory feeding preference experiments, acrylic acid deterred feeding by the sea urchinStrongylocentrotus droebachiensisat concentrations of 0.1 to 2% FM and byS. purpuratusat 0.25 to 2% FM, while the precursor DMSP functioned as a feeding attractant to both sea urchins. In contrast, feeding by the isopodIdotea wosnesenskiiwas not deterred by acrylic acid even at concentrations as high as 8% FM. Our data suggest that DMSP may function as a precursor in an activated defense system in diverse species of temperate macroalgae and may possibly contribute to the widespread success of the Ulvophyceae. This chemical system is also found in unicellular phytoplankton, and presents an opportunity to compare and contrast the ecological role of chemical defense among micro- and macroorganisms.

We characterised and compared dimethylsulfoniopropionate (DMSP) lyase isozymes in crude extracts of 6 axenic Emiliania huxleyi cultures (CCMP 370, 373, 374, 379, 1516, and strain L). This enzyme cleaves DMSP to form dimethyl sulfide (DMS), acrylate and a proton, but the function of this reaction in algae is still poorly understood. Most of the cultures produced high concentrations of intracellular DMSP, which was constant over the growth cycle and ranged from 157 to 242 mM, except for 1516 which had 50 mM DMSP cell–1. Extracts of all strains produced DMS from exogenous DMSP in vitro. DMSP lyases appeared constitutive, but enzyme activity and behaviour varied greatly among strains, and did not correlate with intracellular DMSP concentration. Strains 373 and 379 showed high DMSP lyase activities (12.5 and 6.1 fmol DMS cell–1 min–1, respectively), whereas DMS production was more than 100-fold lower in 370, 374, 1516 and L. This difference was intrinsic and the general pattern of high- and low-activity strains remained true over more than a 1 yr cultivation period. The cleavage reaction was optimal at pH 6 in the strains with high lyase activity and pH 5 was optimal for 374, 1516 and L. Strain 370 showed increasing activity with increasing pH. Experiments with additions of 0.125 to 2 M NaCl indicated halotolerant DMSP lyases in 373, 379 and 374. However, the halophilic DMSP lyases in 370 and L required 1 M NaCl addition for optimal DMSP cleavage, and 1516 showed optimal activity at 2 M NaCl. These results suggest that there are several structurally different DMSP lyase isozymes within E. huxleyi. However, it cannot be ruled out that varying concentrations of DMSP lyase per cell may have contributed to the differences in enzyme activity per cell. Comparison with other algal taxa indicates several families of DMSP lyases, hinting at possibly different cellular locations and functions, and varying DMS production under natural conditions.

In comparison to a large body of literature about battered heterosexual women and a growing body about battered lesbians, this is one of the first published studies that investigates the experiences of battered gay and bisexual men. Results indicated that these men suffered patterns, forms, and frequencies of physical, emotional, and sexual abuse similar to what has been documented by research on battered heterosexual and lesbian women. Likewise, the most commonly reported reasons for staying-namely, hope for change and love for partner-appear to be universal to the experience of being battered. Unlike battered heterosexual women, respondents in this study were not likely to report that being financially trapped was a major reason why they had remained. HIV-status, however, appears to significantly influence their decision to remain. Moreover, lack of knowledge about domestic violence and the lack of availability of appropriate resources play a significant role in same-gender domestic violence victims' decisions to remain. Like battered lesbians, battered gay men infrequently sought assistance from battered women's services and perceived these services as not helpful. By contrast, individual counselors and agencies who provided individual counselors were rated as quite helpful.

For clinical assessment as well as student training, there is a need for information pertaining to the perceptual dimensions of dysphonic voice. To this end, 24 naive listeners judged the similarity of 10 female and 10 male vowel samples, selected from within a narrow range of fundamental frequencies. Most of the perceptual variance for both sets of voices was associated with \"degree of abnormality\" as reflected by perceptual ratings as well as combined acoustic measures, based upon filtered and unfiltered signals. A second perceptual dimension for female voices was associated with high frequency noise as reflected by two acoustic measures: breathiness index (BRI) and a high-frequency power ratio. A second perceptual dimension for male voices was associated with a breathy-overtight continuum as reflected by period deviation (PDdev) and perceptual ratings of breathiness. Results are discussed in terms of perceptual training and the clinical assessment of pathological voices.