108 research outputs found
Invariable biomass-specific primary production of taxonomically discrete picoeukaryote groups across the Atlantic Ocean
No full textOceanic photosynthetic picoeukaryotes (< 3 µm) are responsible for > 40% of total primary production at low latitudes such as the North-Eastern tropical Atlantic. In the world ocean, warmed by climate changes, the expected gradual shift towards smaller primary producers could render the role of photosynthetic picoeukaryotes even more important than they are today. Little is still known, however, about how the taxonomic composition of this highly diverse group affects primary production at the basin scale. Here, we combined flow cytometric cell sorting, NaH14CO3 radiotracer incubations and class-specific fluorescence in situ hybridization (FISH) probes to determine cell- and biomass-specific inorganic carbon fixation rates and taxonomic composition of two major photosynthetic picoeukaryote groups on a ?7500-km-long latitudinal transect across the Atlantic Ocean (Atlantic Meridional Transect, AMT19). We show that even though larger cells have, on average, cell-specific CO2 uptake rates ?5 times higher than the smaller ones, the average biomass-specific uptake is statistically similar for both groups. On the other hand, even at a high taxonomic level, i.e. class, the contributions to both groups by Prymnesiophyceae, Chrysophyceae and Pelagophyceae are significantly different (P < 0.001 in all cases). We therefore conclude that these group's carbon fixation rates are independent of the taxonomic composition of photosynthetic picoeukaryotes across the Atlantic Ocean. Because the above applies across different oceanic regions the diversity changes seem to be a secondary factor determining primary production
Analysis of photosynthetic picoeukaryote community structure along an extended Ellett Line transect in the northern North Atlantic reveals a dominance of novel prymnesiophyte and prasinophyte phylotypes
No full textPhotosynthetic picoeukaryotes (PPEs) of a size <3 mu m can contribute significantly to primary production. Here, PPE community structure was analysed along an extended Ellett Line transect, an area in the North Atlantic well studied by physical oceanographers but largely neglected in the field of microalgal ecology. Distribution patterns of specific PPE classes were determined using dot-blot hybridization analysis, while the taxonomic composition of specific PPE classes was revealed by phylogenetic analysis of plastid 16S rRNA gene sequences. In addition, we performed fluorescent in situ hybridization (FISH) analysis of seawater samples collected along the transect to provide a PCR-independent survey of class level PPE distribution patterns. We found the PPE community was dominated by members of the Prymnesiophyceae, Prasinophyceae and Mamiellophyceae. Interestingly, phylogenetic analysis revealed several novel Prymnesiophyceae and Prasinophyceae phylotypes (with only 85-96% identity to neighbouring sequences) within lineages for which cultured counterparts are unknow
In situ interactions between photosynthetic picoeukaryotes and bacterioplankton in the Atlantic Ocean: evidence for mixotrophy
No full textHeterotrophic bacterioplankton, cyanobacteria and phototrophic picoeukaryotes (< 5 μm in size) numerically dominate planktonic oceanic communities. While feeding on bacterioplankton is often attributed to aplastidic protists, recent evidence suggests that phototrophic picoeukaryotes could be important bacterivores. Here, we present direct visual evidence from the surface mixed layer of the Atlantic Ocean that bacterioplankton are internalized by phototrophic picoeukaryotes. In situ interactions of phototrophic picoeukaryotes and bacterioplankton (specifically Prochlorococcus cyanobacteria and the SAR11 clade) were investigated using a combination of flow cytometric cell sorting and dual tyramide signal amplification fluorescence in situ hybridization. Using this method, we observed plastidic Prymnesiophyceae and Chrysophyceae cells containing Prochlorococcus, and to a lesser extent SAR11 cells. These microscopic observations of in situ microbial trophic interactions demonstrate the frequency and likely selectivity of phototrophic picoeukaryote bacterivory in the surface mixed layer of both the North and South Atlantic subtropical gyres and adjacent equatorial region, broadening our views on the ecological role of the smallest oceanic plastidic protists
On garbage
No full textWhat begins with the fleeting appearance of unrelated phenomena – a mediaeval painting of Hell, ‘magical’ soap, decapitated statues of Marx and Lenin, a seventeenth century ‘perspective house,’ English ‘plotlands’ – becomes, in the course of On Garbage, a subtle and persuasive meditation on the modern human condition and the emergence of Western culture.
How do we decide what is junk, trash and garbage? In an intriguing study of the philosophy and aesthetics of 'waste', John Scanlan suggests that both the matter and spectre of waste create openings into an alternative and all too easily forgotten source of causality - the non-human - and thus reveal a world that does not always bend to the human will. Where modernity has stood for the reorientation of the world of lived experience through the subordination of space, time and nature, ‘garbage’ becomes emblematic of the limits of our attempt to make the world, in Martin Heidegger’s words, ‘a calculable coherence of forces’ at our disposal.
Pursuing the shadow life of Western culture the author engages the ideas of a wide range of thinkers, including Kant, Freud, Nietzsche and Heidegger, novelists such as Laszlo Krasnahorkai, Ivan Klima and Don DeLillo, and considers the work of a host of artists, including Joseph Cornell, Robert Rauschenberg and Cornelia Parke
Basin-scale distribution patterns of picocyanobacterial lineages in the Atlantic Ocean
No full textMarine picocyanobacteria of the genera Prochlorococcus and Synechococcus are major contributors to oceanic primary production. The genera are genetically diverse, comprising several known ecotypes or lineages. However, little is known of the distribution of these lineages over large geographic areas. Here, we analysed the relative abundance of Prochlorococcus ecotypes and Synechococcus lineages at the ocean basin scale along an Atlantic Meridional Transect (AMT) using dot blot hybridization and fluorescence in situ hybridization (FISH) techniques. The transect covered several contrasting oceanic provinces (gyres, upwelling, temperate regions) as well as environmentally 'equivalent' regions in the northern and southern hemisphere (northern and southern gyres and temperate regions). Flow cytometric data revealed a discrete separation in abundance of major picocyanobacterial genera. Prochlorococcus reached highest abundance in oligotrophic regions, while more mesotrophic waters were dominated by Synechococcus. Individual genetic lineages of both Prochlorococcus and Synechococcus showed highly similar distributions in corresponding regions in the northern and southern hemisphere. In addition, Prochlorococcus showed a distinctive depth distribution, with HLI and HLII ecotypes near the surface and co-occurring LL ecotypes further down in the water column. Conversely, Synechococcus generally revealed no obvious depth preference, but did show highly specific distribution at the horizontal scale, with clades I and IV particularly dominating temperate, mesotrophic waters in both the northern and southern hemispheres. The data clearly reveal that specific picocyanobacterial lineages proliferate in similar oceanic provinces separated by large spatial scales. Furthermore, comparison with an earlier AMT dataset suggests that basin scale distribution patterns for Prochlorococcus ecotypes are remarkably reproducible from year to year
Online exposure for spider fear: Treatment completion and habituation outcomes
No full textThis research aimed to investigate habituation to spider images during an online exposure treatment (www.feardrop.com) among participants with a high fear of spiders. Participants (N = 392) undertook a 10-stage online exposure treatment with a stage length of either 180 or 360 seconds. Four Subjective Units of Distress Scale (SUDS) ratings were taken throughout each stage. Treatment completion was found to be a significant challenge, with less than one-third (30%) completing at least one stage of the program. Those in the shorter stage length condition were significantly more likely to complete the first stage relative to those in the longer stage length condition (43% vs. 16%). SUDS ratings decreased significantly across time at Stage 1, suggesting habituation of self-reported anxiety and there was an overall reduction in SUDS ratings at the second relative to the first stage, suggesting generalisation of habituation. The greatest habituation was observed among those with high anticipatory anxiety (pre-exposure SUDS rating), high total exposure time, and younger age. There was preliminary evidence for improvement in symptoms of spider fear at post-treatment. Directions for future research include strategies to facilitate treatment completion, evaluation of treatment outcomes, and expansion to include a range of specific fears. Author(s): Allison J. Matthews 1 * | Joel D. Scanlan 2 | Ken C. Kirkby
PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus
No full textPrevious microarray analyses have shown a key role for the two-component system PhoBR (SYNW0947, SYNW0948) in the regulation of P transport and metabolism in the marine cyanobacterium Synechococcus sp. WH8102. However, there is some evidence that another regulator, SYNW1019 (PtrA), probably under the control of PhoBR, is involved in the response to P depletion. PtrA is a member of the cAMP receptor protein transcriptional regulator family that shows homology to NtcA, the global nitrogen regulator in cyanobacteria. To define the role of this regulator, we constructed a mutant by insertional inactivation and compared the physiology of wild-type Synechcococcus sp. WH8102 with the ptrA mutant under P-replete and P-stress conditions. In response to P stress the ptrA mutant failed to upregulate phosphatase activity. Microarrays and quantitative RT-PCR indicate that a subset of the Pho regulon is controlled by PtrA, including two phosphatases, a predicted phytase and a gene of unknown function psip1 (SYNW0165), all of which are highly upregulated during P limitation. Electrophoretic mobility shift assays indicate binding of overexpressed PtrA to promoter sequences upstream of the induced genes. This work suggests a two-tiered response to P depletion in this strain, the first being PhoB-dependent induction of high-affinity PO4 transporters, and the second the PtrA-dependent induction of phosphatases for scavenging organic P. The levels of numerous other transcripts are also directly or indirectly influenced by PtrA, including those involved in cell-surface modification, metal uptake, photosynthesis, stress responses and other metabolic processes, which may indicate a wider role for PtrA in cellular regulation in marine picocyanobacteria
Choice of diet impacts the incidence of stroke in the spontaneously hypertensive stroke-prone rat model
No full textGlee 1946 Information
No full text38th annual GleeGlee 1946 was dedicated to Roy S. "Spec" Keene.The winning class of Glee 1946 was the Sophomores (class of 1948); Second Place - Juniors (class of 1947); Third Place - Freshmen (class of 1949); Fourth Place - Seniors (class of 1946)Manager: Jerry Quillin; Executive: Dick Spooner; General: Evelyn Jory, Jack Hedgecock, Nancy Hoak, Jerry Quillin; Program: Pauline Bristlin, Eileen Grenfell, Wesley Hedeen; Publicity: Marilee Olson; Tickets: Barbara MacDuffee, Betty Larson, Dona Adams, Elva Grant; Stage: Herb Lucas, Paul Whitmore, Lee Zumwalt, Dale Mansfield; Formation: Thyra Jean Currey ('46), Melva Williamson ('47), Pat McCargar ('48), Courtney Jones ('48), Bob Busick ('49); Decorations: Joyce McCracken, Mary Phelps, Barbara Scanlan, Thema Bjerke, Norma Hoffine, Bill Bonnington, Dave Bristow, R. J. Chance, Dwayne Wetstein, Ella Tatlow, Marain Gordon, Helen Gordon, Pat Holtz; Lights: Bob Nickoloff, Blaine Hanks, Dave Nyberg; Chairs: Sam Barker, Dave Bristow, Morris McElwee, Bill Bonnington; Entertainment: Roger Fogelquist; Music: Wes McWain ('46), Marian Erickson ('47), Alice Rose ('47), Sam Frickey ('48), Garnet Fahnestock ('49); Lyrics: Senior Class ('46), Alice Rose ('47), Sophomore Class ('48), Edith Fairham ('49
Trafficking
No full textIn cities the world over, we are able to determine stability in daily existence, to identify with our social spaces, because modes of transport have become essential components of subjective autonomy. But would it not be just as accurate to say that in transit, modern life puts the self in abeyance? The author argues that the ways we allow ourselves to be moved around in "traffic space" create a passivity that renders almost invisible the complex mechanics of movement, which we become alert to only at the moment of breakdown, precisely when they become a threat to autonomy. Our trafficking has an almost narcotic effect, rendering us immobile against the continual movements that constitute urban life, one that also magnifies out of all proportion the accidents or aberrations that sometimes disturb our traffic space, making it seem as if we may easily descend into an uncontrollable chaos
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