RESUMEN
Downy mildew of grape caused by Plasmopara viticola is a global pathogen of economic importance to commercial viticulture. In contrast to populations in the northern hemisphere, few studies have investigated the population biology, genetic diversity, and origin of the pathogen in Australian production systems. DNA was extracted from 381 P. viticola samples from Vitis vinifera and alternate hosts collected via fresh and herbarium leaves from populations within Australia and Whatman FTA cards from North America, Brazil, and Uruguay. A total of 32 DNA samples were provided from a French population. The populations were genotyped using 16 polymorphic microsatellite markers. Representative samples from within Australia, Brazil, and Uruguay were also genotyped to determine which of the cryptic species (clades) within the P. viticola species complex were present. Our findings suggest the Australian and South American populations of P. viticola are more closely related to the European population than the North American population, the reported source of origin of the pathogen. The Western Australian population had similarities to the South Australian population, and the tight clustering of samples suggests a single introduction into Western Australia. P. viticola clade aestivalis was the only clade detected in Australian and South American populations. Analysis of the Western Australian population suggests that it is reproducing clonally, but additional research is required to determine the mechanism as to how this is occurring.
Asunto(s)
Genética de Población , Oomicetos , Vitis , Australia , Brasil , América del Norte , Oomicetos/clasificación , Oomicetos/genética , Enfermedades de las Plantas/parasitología , Uruguay , Vitis/parasitologíaRESUMEN
We investigated biomass, size-structure, composition, depth distributions and spatial variability of the phytoplankton community in the Costa Rica Dome (CRD) in June-July 2010. Euphotic zone profiles were sampled daily during Lagrangian experiments in and out of the dome region, and the community was analyzed using a combination of digital epifluorescence microscopy, flow cytometry and HPLC pigments. The mean depth-integrated biomass of phytoplankton ranged 2-fold, from 1089 to 1858 mg C m-2 (mean ± SE = 1378 ± 112 mg C m-2), among 4 water parcels tracked for 4 days. Corresponding mean (±SE) integrated values for total chlorophyll a (Chl a) and the ratio of autotrophic carbon to Chl a were 24.1 ± 1.5 mg Chl a m-2 and 57.5 ± 3.4, respectively. Absolute and relative contributions of picophytoplankton (â¼60%), Synechococcus (>33%) and Prochlorococcus (17%) to phytoplankton community biomass were highest in the central dome region, while >20 µm phytoplankton accounted for ≤10%, and diatoms <2%, of biomass in all areas. Nonetheless, autotrophic flagellates, dominated by dinoflagellates, exceeded biomass contributions of Synechococcus at all locations. Order-of-magnitude discrepancies in the relative contributions of diatoms (overestimated) and dinoflagellates (underestimated) based on diagnostic pigments relative to microscopy highlight potential significant biases associated with making community inferences from pigments.
RESUMEN
During summer 2010, we investigated phytoplankton production and growth rates at 19 stations in the eastern tropical Pacific, where winds and strong opposing currents generate the Costa Rica Dome (CRD), an open-ocean upwelling feature. Primary production (14C-incorporation) and group-specific growth and net growth rates (two-treatment seawater dilution method) were estimated from samples incubated in situ at eight depths. Our cruise coincided with a mild El Niño event, and only weak upwelling was observed in the CRD. Nevertheless, the highest phytoplankton abundances were found near the dome center. However, mixed-layer growth rates were lowest in the dome center (â¼0.5-0.9 day-1), but higher on the edge of the dome (â¼0.9-1.0 day-1) and in adjacent coastal waters (0.9-1.3 day-1). We found good agreement between independent methods to estimate growth rates. Mixed-layer growth rates of Prochlorococcus and Synechococcus were largely balanced by mortality, whereas eukaryotic phytoplankton showed positive net growth (â¼0.5-0.6 day-1), that is, growth available to support larger (mesozooplankton) consumer biomass. These are the first group-specific phytoplankton rate estimates in this region, and they demonstrate that integrated primary production is high, exceeding 1 g C m-2 day-1 on average, even during a period of reduced upwelling.
RESUMEN
We determined the net rate of biogenic silica (bSiO2) production and estimated the diatom contribution to new production and organic matter export in the Costa Rica Dome during summer 2010. The shallow thermocline significantly reduces bSiO2 dissolution rates below the mixed layer, leading to significant enhancement of bSiO2 relative to organic matter (silicate-pump condition). This may explain why deep export of bSiO2 in this region is elevated by an order of magnitude relative to comparable systems. Diatom carbon, relative to autotrophic carbon, was low (<3%); however, the contribution of diatoms to new production averaged 3 and 13% using independent approaches. The 4-old discrepancy between methods may be explained by a low average C:Si ratio (â¼1.4) for the net produced diatom C relative to the net produced bSiO2. We speculate that this low production ratio is not the result of reduced C, but may arise from a significant contribution of non-diatom silicifying organisms to bSiO2 production. The contribution of diatoms to organic matter export was minor (5.7%). These results, and those of the broader project, suggest substantial food-web transformation of diatom organic matter in the euphotic zone, which creates enriched bSiO2 relative to organic matter within the exported material.
RESUMEN
We investigated biomass and composition of heterotrophic microbes in the Costa Rica Dome during June-July 2010 as part of a broader study of plankton trophic dynamics. Because picophytoplankton (<2 µm) are known to dominate in this unique upwelling region, we hypothesized tight biomass relationships between size-determined predator-prey pairs (i.e. picoplankton-nano-grazers, nanoplankton-micro-grazers) within the microbial community. Integrated biomass of heterotrophic bacteria ranged from 180 to 487 mg C m-2 and was significantly correlated with total autotrophic carbon. Heterotrophic protist (H-protist) biomass ranged more narrowly from 488 to 545 mg C m-2, and was comprised of 60% dinoflagellates, 30% other flagellates and 11% ciliates. Nano-sized (<20 µm) protists accounted for the majority (57%) of grazer biomass and were positively correlated with picoplankton, partially supporting our hypothesis, but nanoplankton and micro-grazers (>20 µm) were not significantly correlated. The relative constancy of H-protist biomass among locations despite clear changes in integrated autotrophic biomass, Chl a, and primary production suggests that mesozooplankton may exert a tight top-down control on micro-grazers. Biomass-specific consumption rates of phytoplankton by protistan grazers suggest an instantaneous growth rate of 0.52 day-1 for H-protists, similar to the growth rate of phytoplankton and consistent with a trophically balanced ecosystem dominated by pico-nanoplankton interactions.
RESUMEN
The Costa Rica Dome is a picophytoplankton-dominated, open-ocean upwelling system in the Eastern Tropical Pacific that overlies the ocean's largest oxygen minimum zone. To investigate the efficiency of the biological pump in this unique area, we used shallow (90-150 m) drifting sediment traps and 234Th:238U deficiency measurements to determine export fluxes of carbon, nitrogen and phosphorus in sinking particles. Simultaneous measurements of nitrate uptake and shallow water nitrification allowed us to assess the equilibrium balance of new and export production over a monthly timescale. While f-ratios (new:total production) were reasonably high (0.36 ± 0.12, mean ± standard deviation), export efficiencies were considerably lower. Sediment traps suggested e-ratios (export/14C-primary production) at 90-100 m ranging from 0.053 to 0.067. ThE-ratios (234Th disequilibrium-derived export) ranged from 0.038 to 0.088. C:N and N:P stoichiometries of sinking material were both greater than canonical (Redfield) ratios or measured C:N of suspended particulates, and they increased with depth, suggesting that both nitrogen and phosphorus were preferentially remineralized from sinking particles. Our results are consistent with an ecosystem in which mesozooplankton play a major role in energy transfer to higher trophic levels but are relatively inefficient in mediating vertical carbon flux to depth, leading to an imbalance between new production and sinking flux.
RESUMEN
We investigated phytoplankton production rates and grazing fates in the Costa Rica Dome (CRD) during summer 2010 based on dilution depth profiles analyzed by flow cytometry and pigments and mesozooplankton grazing assessed by gut fluorescence. Three community production estimates, from 14C uptake (1025 ± 113 mg C m-2 day-1) and from dilution experiments analyzed for total Chla (990 ± 106 mg C m-2 day-1) and flow cytometry populations (862 ± 71 mg C m-2 day-1), exceeded regional ship-based values by 2-3-fold. Picophytoplankton accounted for 56% of community biomass and 39% of production. Production profiles extended deeper for Prochlorococcus (PRO) and picoeukaryotes than for Synechococcus (SYN) and larger eukaryotes, but 93% of total production occurred above 40 m. Microzooplankton consumed all PRO and SYN growth and two-third of total production. Positive net growth of larger eukaryotes in the upper 40 m was balanced by independently measured consumption by mesozooplankton. Among larger eukaryotes, diatoms contributed â¼3% to production. On the basis of this analysis, the CRD region is characterized by high production and grazing turnover, comparable with or higher than estimates for the eastern equatorial Pacific. The region nonetheless displays characteristics atypical of high productivity, such as picophytoplankton dominance and suppressed diatom roles.
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BACKGROUND: Oxygen is commonly administered to patients with ST-elevation-myocardial infarction despite previous studies suggesting a possible increase in myocardial injury as a result of coronary vasoconstriction and heightened oxidative stress. METHODS AND RESULTS: We conducted a multicenter, prospective, randomized, controlled trial comparing oxygen (8 L/min) with no supplemental oxygen in patients with ST-elevation-myocardial infarction diagnosed on paramedic 12-lead ECG. Of 638 patients randomized, 441 patients had confirmed ST-elevation-myocardial infarction and underwent primary end-point analysis. The primary end point was myocardial infarct size as assessed by cardiac enzymes, troponin I, and creatine kinase. Secondary end points included recurrent myocardial infarction, cardiac arrhythmia, and myocardial infarct size assessed by cardiac magnetic resonance imaging at 6 months. Mean peak troponin was similar in the oxygen and no oxygen groups (57.4 versus 48.0 µg/L; ratio, 1.20; 95% confidence interval, 0.92-1.56; P=0.18). There was a significant increase in mean peak creatine kinase in the oxygen group compared with the no oxygen group (1948 versus 1543 U/L; means ratio, 1.27; 95% confidence interval, 1.04-1.52; P=0.01). There was an increase in the rate of recurrent myocardial infarction in the oxygen group compared with the no oxygen group (5.5% versus 0.9%; P=0.006) and an increase in frequency of cardiac arrhythmia (40.4% versus 31.4%; P=0.05). At 6 months, the oxygen group had an increase in myocardial infarct size on cardiac magnetic resonance (n=139; 20.3 versus 13.1 g; P=0.04). CONCLUSION: Supplemental oxygen therapy in patients with ST-elevation-myocardial infarction but without hypoxia may increase early myocardial injury and was associated with larger myocardial infarct size assessed at 6 months. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01272713.
Asunto(s)
Aire , Servicios Médicos de Urgencia/métodos , Infarto del Miocardio/terapia , Terapia por Inhalación de Oxígeno/efectos adversos , Oxígeno/efectos adversos , Anciano , Ambulancias , Aspirina/uso terapéutico , Biomarcadores , Dolor en el Pecho/etiología , Terapia Combinada , Circulación Coronaria/efectos de los fármacos , Vasos Coronarios/efectos de los fármacos , Vasos Coronarios/fisiopatología , Creatina Quinasa/sangre , Electrocardiografía , Urgencias Médicas , Femenino , Humanos , Hipoxia/sangre , Hipoxia/etiología , Hipoxia/prevención & control , Masculino , Persona de Mediana Edad , Infarto del Miocardio/sangre , Infarto del Miocardio/patología , Infarto del Miocardio/fisiopatología , Miocardio/patología , Oxígeno/sangre , Oxígeno/farmacología , Presión Parcial , Estudios Prospectivos , Troponina I/sangre , Procedimientos Innecesarios , Resistencia Vascular/efectos de los fármacos , Victoria/epidemiologíaRESUMEN
The impact of the Prehospital Trauma Life Support (PHTLS) programme, introduced in Trinidad and Tobago in 1992, was assessed by questionnaires completed by 26 medical personnel (MP); 71 ambulance personnel (AP); and 50 non ambulance paramedical personnel (NAP). Of the 23 MP, 45 AP and 38 NAP who were aware of the programme, 19 (82.6 percent) MP, 40(88.9 percent) AP and 25 (65.8 percent) NAP were able to differentiate personnel that had taken the PHTLS programme based on their performance. 32 (71.1 percent) of the AP were PHTLS trained. 24 (53.3 percent) and 4 (9 percent) of the AP identified poor equipment and poor supervision, respectively, as reasons for difficulty in applying PHTLS principles. Improvements observed among those completing the PHTLS programme were: improved resuscitation techniques by 20 (86.9 percent) MP, 38 (84.4 percent) AP and 27 (71.1 percent) NAP; better vital signs recording by 8 (34.8 percent) MP, 27 (60 percent) AP and 8 (21.1 percent) NAP; improved immobilization by 23 (100 percent) MP, 40 (88.9 percent) AP and 33 (86.8 percent) NAP: better haemorrhage control by 22 (95.6 percent) MP, 40 (88.9 percent) AP and 24 (63.2 percent) NAP; appropriate splinting of fractures by 23 (100 percent) MP, 40 (88.9 percent) AP and 32 (84.2 percent) NAP: and increased utilization of oxygen by 15 (65.2 percent) MP, 31 (68.9 percent) AP and 21 (55.3 percent) NAP. 32 (71.1 percent) AP with PHTLS training indicated improvement in their ability to resuscitate and transport trauma victims, with 42 (93.3 percent) reporting improvement in overall prehospital care. Medical, paramedical and ambulance personnel all perceive a significant positive impact of PHTLS training on prehospital trauma care. Although improvements in supervision, documentation and equipment are still required, improved trauma resuscitative techniques after PHTLS training should improve trauma patient outcome in Trinidad and Tobago. (AU)
Asunto(s)
Sistemas de Manutención de la Vida/estadística & datos numéricos , Recolección de Datos , Encuestas y Cuestionarios , Trinidad y TobagoRESUMEN
In April 1971, a nationwide outbreak of typhoid fever involving 132 persons occurred in Trinidad; there were no deaths. Eighty per cent of cases occurred in children ages 5-14, and more than 90 percent of ill persons lived or went to school in the main towns or in smaller communities along their connecting roads. The epidemic curve suggested a common source, and a series of food preference questionaires implicated a nationally distributed ice cream product. Further investigation indicated that the product was distributed on only one day, March 23. The mean incubation period was 19 days, and the attack rate for those at risk was slightly greater than 1 percent. Samples of the ice cream product obtained a month after the outbreak were found to contain greater than 1100 Escherichia coli per 100 ml. Inspection of the plant revealed frequent hand contact with the product and an absence of pasteurization facilities. Although rectal swabs and stool cultures obtained after purgation from employees failed to identify the carrier, epidemiologic evidence suggested that an employee in the plant, rather than a contaminated ingredient, was the source of the outbreak. This outbreak emphasizes the need for mandatory pasteurization of milk and ice cream products, especially when strict sanitary procedures cannot be adhered to or enforced (AU)