RESUMEN
Species exploiting seasonal environments must alter timings of key life-history events in response to large-scale climatic changes in order to maintain trophic synchrony with required resources. Yet, substantial among-species variation in long-term phenological changes has been observed. Advancing from simply describing such variation towards predicting future phenological responses requires studies that rigorously quantify and explain variation in the direction and magnitude of changing timings across diverse species in relation to key ecological and life-history variables. Accordingly, we fitted multi-quantile regressions to 59 years of multi-species data on spring and autumn bird migration timings through northern Scotland. We demonstrate substantial variation in changes in timings among 72 species, and tested whether such variation can be explained by species ecology, life-history and changes in local abundance. Consistent with predictions, species that advanced their migration timing in one or both seasons had more seasonally restricted diet types, fewer suitable breeding habitat types, shorter generation lengths and capability to produce multiple offspring broods per year. In contrast, species with less seasonally restricted diet types and that produce single annual offspring broods, showed no change. Meanwhile, contrary to prediction, long-distance and short-distance migrants advanced migration timings similarly. Changes in migration timing also varied with changes in local migratory abundance, such that species with increasing seasonal abundance apparently altered their migration timing, whilst species with decreasing abundance did not. Such patterns broadly concur with expectation given adaptive changes in migration timing. However, we demonstrate that similar patterns can be generated by numerical sampling given changing local abundances. Any apparent phenology-abundance relationships should, therefore, be carefully validated and interpreted. Overall, our results show that migrant bird species with differing ecologies and life-histories showed systematically differing phenological changes over six decades contextualised by large-scale environmental changes, potentially facilitating future predictions and altering temporal dynamics of seasonal species co-occurrences.
Asunto(s)
Migración Animal , Aves , Estaciones del Año , Animales , Migración Animal/fisiología , Aves/fisiología , Escocia , Ecosistema , Rasgos de la Historia de Vida , Cambio Climático , DietaRESUMEN
AIMS: Determine the wheat rhizosphere competence of Trichoderma gamsii strain A5MH and in planta suppression of the Pythium root and Fusarium crown rot pathogens Globisporangium irregulare and Fusarium pseudograminearum. METHODS AND RESULTS: Wheat was continuously cropped (eight years) at a minimum tillage, low growing season rainfall (GSR ≤ 170 mm) site shown as highly conducive to Pythium root and Fusarium crown rots. Root isolation frequency (RIF) and qPCR were used to determine the rhizosphere dynamics of strain A5MH and the target pathogens at tillering, grain harvest, and in postharvest stubble over the final 2 years. Strain A5MH actively colonized the wheat rhizosphere throughout both growing seasons, had high root abundance at harvest [log 4.5 genome copies (GC) g-1] and persisted in standing stubble for at least 293-d postinoculation. Globisporangium irregulare was most abundant in roots at tillering, whereas F. pseudograminearum was only abundant at harvest and up to 9-fold greater in the drier, second year (GSR 105 mm). Strain A5MH decreased RIF of both pathogens by up to 40%, root abundance of G. irregulare by 100-fold, and F. pseudogaminearum by 700-fold, but was ineffective against crown rot in the second year when pathogen abundance was >log 6.0 GC g-1 root. Strain A5MH increased crop emergence and tillering biomass by up to 40%. CONCLUSIONS: Further trials are required to determine if the A5MH-induced pathogen suppression translates to yield improvements in higher rainfall regions where non-cereal rotations reduce crown rot inoculum.
Asunto(s)
Fusarium , Hypocreales , Pythium , Estaciones del Año , Triticum , Fusarium/genética , Rizosfera , Enfermedades de las Plantas/prevención & control , Grano ComestibleRESUMEN
BACKGROUND: Vasovagal reactions (VVRs) are the most common acute complications of blood donation. Responsible for substantial morbidity, they also reduce the likelihood of repeated donations and are disruptive and costly for blood services. Although blood establishments worldwide have adopted different strategies to prevent VVRs (including water loading and applied muscle tension [AMT]), robust evidence is limited. The Strategies to Improve Donor Experiences (STRIDES) trial aims to reliably assess the impact of four different interventions to prevent VVRs among blood donors. METHODS: STRIDES is a cluster-randomised cross-over/stepped-wedge factorial trial of four interventions to reduce VVRs involving about 1.4 million whole blood donors enrolled from all 73 blood donation sites (mobile teams and donor centres) of National Health Service Blood and Transplant (NHSBT) in England. Each site ("cluster") has been randomly allocated to receive one or more interventions during a 36-month period, using principles of cross-over, stepped-wedge and factorial trial design to assign the sequence of interventions. Each of the four interventions is compared to NHSBT's current practices: (i) 500-ml isotonic drink before donation (vs current 500-ml plain water); (ii) 3-min rest on donation chair after donation (vs current 2 min); (iii) new modified AMT (vs current practice of AMT); and (iv) psychosocial intervention using preparatory materials (vs current practice of nothing). The primary outcome is the number of in-session VVRs with loss of consciousness (i.e. episodes involving loss of consciousness of any duration, with or without additional complications). Secondary outcomes include all in-session VVRs (i.e. with and without loss of consciousness), all delayed VVRs (i.e. those occurring after leaving the venue) and any in-session non-VVR adverse events or reactions. DISCUSSION: The STRIDES trial should yield novel information about interventions, singly and in combination, for the prevention of VVRs, with the aim of generating policy-shaping evidence to help inform blood services to improve donor health, donor experience, and service efficiency. TRIAL REGISTRATION: ISRCTN: 10412338. Registration date: October 24, 2019.
Asunto(s)
Donantes de Sangre , Síncope Vasovagal , Humanos , Medicina Estatal , Síncope Vasovagal/diagnóstico , Síncope Vasovagal/etiología , Síncope Vasovagal/prevención & control , Agua , Donación de SangreRESUMEN
AIMS: Develop quantitative assays (qPCR) to determine the wheat rhizosphere competence of inoculant strains Bacillus amyloliquefaciens W10 and Pseudomonas protegens FD6, and their suppressive efficacies against the sharp eyespot pathogen Rhizoctonia cerealis. METHODS AND RESULTS: Antimicrobial metabolites of strains W10 and FD6 decreased in vitro growth of R. cerealis. A qPCR assay for strain W10 was designed from a diagnostic AFLP fragment and the rhizosphere dynamics of both strains in wheat seedlings were compared by culture-dependent (CFU) and qPCR assays. The qPCR minimum detection limits for strains W10 and FD6 were log 3.04 and log 4.03 genome (cell) equivalents g-1 soil, respectively. Inoculant soil and rhizosphere abundance determined by CFU and qPCR were highly correlated (r > 0.91). In wheat bioassays, rhizosphere abundance of strain FD6 was up to 80-fold greater (P < 0.001) than strain W10 at 14 and 28 days postinoculation. Both inoculants reduced (P < 0.05) rhizosphere soil and root abundance of R. cerealis by up to 3-fold. CONCLUSIONS: Strain FD6 exhibited greater abundance in wheat roots and rhizosphere soil than strain W10 and both inoculants decreased the rhizosphere abundance of R. cerealis.
Asunto(s)
Bacillus amyloliquefaciens , Bacillus amyloliquefaciens/genética , Triticum , Rizosfera , Suelo , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Rhizoctonia , Enfermedades de las Plantas/prevención & controlRESUMEN
The bacterium Pseudomonas sp. strain JP233 has been reported to efficiently solubilize sparingly soluble inorganic phosphate, promote plant growth and significantly reduce phosphorus (P) leaching loss from soil. The production of 2-keto gluconic acid (2KGA) by strain JP233 was identified as the main active metabolite responsible for phosphate solubilization. However, the genetic basis of phosphate solubilization and plant-growth promotion remained unclear. As a result, the genome of JP233 was sequenced and analyzed in this study. The JP233 genome consists of a circular chromosome with a size of 5,617,746 bp and a GC content of 62.86%. No plasmids were detected in the genome. There were 5097 protein-coding sequences (CDSs) predicted in the genome. Phylogenetic analyses based on genomes of related Pseudomonas spp. identified strain JP233 as Pseudomonas asiatica. Comparative pangenomic analysis among 9 P. asiatica strains identified 4080 core gene clusters and 111 singleton genes present only in JP233. Genes associated with 2KGA production detected in strain JP233, included those encoding glucose dehydrogenase, pyrroloquinoline quinone and gluoconate dehydrogenase. Genes associated with mechanisms of plant-growth promotion and nutrient acquisition detected in JP233 included those involved in IAA biosynthesis, ethylene catabolism and siderophore production. Numerous genes associated with other properties beneficial to plant growth were also detected in JP233, included those involved in production of acetoin, 2,3-butanediol, trehalose, and resistance to heavy metals. This study provides the genetic basis to elucidate the plant-growth promoting and bio-remediation properties of strain JP233 and its potential applications in agriculture and industry.
Asunto(s)
Fosfatos , Pseudomonas , Fosfatos/metabolismo , Filogenia , GenómicaRESUMEN
Phosphorus (P) is one of the most limiting nutrients in global agricultural ecosystems, and phosphorus-solubilizing bacteria (PSB) can convert insoluble P into soluble P, thereby improving the absorption and use of soil P by plants. Increasing leaching loss of soil P due to PSB that could lead to water eutrophication is a major concern, although no direct experimental evidence is available to evaluate these effects. In this study, a highly efficient PSB strain, Pseudomonas sp. JP233, was isolated from soil and its P-solubilizing agent was identified by metabolomics and HPLC analyses. The effects of JP233 on P contents in soil leachates were also analyzed by microcosm leaching experiments in the absence and presence of maize. JP233 could solubilize insoluble P into soluble forms, and the molybdate reactive phosphorus (MRP) content reached 258.07 mg/L in NBRIP medium containing 5 g/L Ca3(PO4)2 within 48 h. Metabolomics analysis demonstrated that the organic acid involved in JP233 P solubilization was primarily 2-keto gluconic acid (2KGA). Further, HPLC analysis revealed that 2KGA contents rapidly accumulated to 19.33 mg/mL within 48 h. Microcosm leaching experiments showed that MRP and total phosphorus (TP) contents in soil leaching solutions were not significantly higher after JP233 inoculation. However, inoculation with JP233 into maize plant soils significantly decreased MRP and TP contents in the soil leaching solutions on days 14 (P < 0.01), 21 (P < 0.01), and 28 (P < 0.05). Inoculation with strain JP233 also significantly increased the biomass of maize aerial components and that of whole plants (P < 0.05). Thus, strain JP233 exhibited a significant plant-growth-promoting effect on maize development. In conclusion, the application of PSB into soils does not significantly increase P leachate loss. Rather, the application of PSB can help reduce P leachate loss, while significantly promoting plant absorption and use of soil P.
RESUMEN
Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (PbHD) in Shanghai in order to determine the extent and exposure risks of PbHD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (PbIC). The mean concentration of PbHD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of PbIC of household dust samples (208Pb/206Pb: 2.1096 ± 0.0054; 207Pb/206Pb: 0.8648 ± 0.0025) are a close match to PbIC of coal combustion and solid waste incineration and fit well with those of outdoor air PbIC and urban surface soil PbIC of Shanghai. The study shows that children living in Shanghai are subject to PbHD exposure, with children living in the homes with lower average price having increased susceptibility to PbHD exposure. The data indicate that PbHD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.
Asunto(s)
Polvo , Plomo , Niño , China , Polvo/análisis , Exposición a Riesgos Ambientales/análisis , Monitoreo del Ambiente , Humanos , SueloRESUMEN
VegeSafe is a national community science initiative aimed at characterising soils in Australian residential gardens and community gardens. The program has been operating for over 5 years and has generated soil metal(loid) data from over 8600 residential garden and community garden soil samples, submitted by almost 2000 community scientists. The VegeSafe program represents the largest archive of soil metal(loid) data and associated metadata for residential garden soils in Australia. Samples were collected across Australia, with 61% of samples collected from NSW (n = 5284), Victoria (VIC) 20% (n = 1688) of samples and Queensland (QLD) 7% (n = 592) of samples. Soil metal(loid) data obtained by analysis of bulk soil samples by portable X-ray florescence spectrometry (pXRF) for As, Cu, Cr Mn, Pb and Zn showed spatial patterns of greater soil metal(loid) concentrations around city areas, particularly in NSW and VIC. The Australian Health Investigation Levels for low-density residential land uses (HIL-A) were used in this study as guideline values for soil metal(loid) concentrations. Overall, there was a relatively small number of HIL-A exceedances in the dataset, with most metal(loid)s exceeding their HIL-A concentration in < 5% of incidences. The notable exception to this was for Pb, which had HIL-A (300 mg/kg) exceeded in 27% (n = 1427) of samples in NSW, 17% (n = 280) in VIC and 10% (n = 61) in QLD. Through the power of community engagement and community science, the VegeSafe program presents an unprecedented insight into soil metal(loid) concentrations in Australian residential gardens.
Asunto(s)
Monitoreo del Ambiente , Jardines , Metales/análisis , Contaminantes del Suelo/análisis , Suelo/química , Australia , Ciudades , Investigación Participativa Basada en la Comunidad/organización & administración , Monitoreo del Ambiente/métodos , Monitoreo del Ambiente/estadística & datos numéricos , Queensland , VictoriaRESUMEN
Leadership research has been encumbered by a proliferation of constructs and measures, despite little evidence that each is sufficiently conceptually and operationally distinct from the others. We draw from research on subordinates' implicit theories of leader behavior, behaviorally anchored rating scales, and decision making to argue that leader affect (i.e., the degree to which subordinates have positive and negative feelings about their supervisors) underlies the common variance shared by many leadership measures. To explore this possibility, we developed and validated measures of positive and negative leader affect (i.e., the Leader Affect Questionnaires; LAQs). We conducted 10 studies to develop the five-item positive and negative LAQs and to examine their convergent, discriminant, predictive, and criterion-related validity. We conclude that a) the LAQs provide highly reliable and valid tools for assessing subordinates' evaluations of their leaders; b) there is significant overlap between existing leadership measures, and a large proportion of this overlap is a function of the affect captured by the LAQs; c) when the LAQs are used as control variables, in most cases, they reduce the strength of relationships between leadership measures and other variables; d) the LAQs account for significant variance in outcomes beyond that explained by other leadership measures; and e) there is a considerable amount of unexplained variance between leadership measures that the LAQs do not capture. Research suggestions are provided and the implications of our results are discussed. (PsycINFO Database Record
Asunto(s)
Afecto , Empleo/psicología , Relaciones Interpersonales , Liderazgo , Psicometría/instrumentación , Percepción Social , Adulto , Femenino , Humanos , Masculino , Psicometría/métodos , Psicometría/normasRESUMEN
Phenological changes in key seasonally expressed life-history traits occurring across periods of climatic and environmental change can cause temporal mismatches between interacting species, and thereby impact population and community dynamics. However, studies quantifying long-term phenological changes have commonly only measured variation occurring in spring, measured as the first or mean dates on which focal traits or events were observed. Few studies have considered seasonally paired events spanning spring and autumn or tested the key assumption that single convenient metrics accurately capture entire event distributions. We used 60 years (1955-2014) of daily bird migration census data from Fair Isle, Scotland, to comprehensively quantify the degree to which the full distributions of spring and autumn migration timing of 13 species of long-distance migratory bird changed across a period of substantial climatic and environmental change. In most species, mean spring and autumn migration dates changed little. However, the early migration phase (≤10th percentile date) commonly got earlier, while the late migration phase (≥90th percentile date) commonly got later. Consequently, species' total migration durations typically lengthened across years. Spring and autumn migration phenologies were not consistently correlated within or between years within species and hence were not tightly coupled. Furthermore, different metrics quantifying different aspects of migration phenology within seasons were not strongly cross-correlated, meaning that no single metric adequately described the full pattern of phenological change. These analyses therefore reveal complex patterns of simultaneous advancement, temporal stability and delay in spring and autumn migration phenologies, altering species' life-history structures. Additionally, they demonstrate that this complexity is only revealed if multiple metrics encompassing entire seasonal event distributions, rather than single metrics, are used to quantify phenological change. Existing evidence of long-term phenological changes detected using only one or two metrics should consequently be interpreted cautiously because divergent changes occurring simultaneously could potentially have remained undetected.
Asunto(s)
Migración Animal , Aves , Animales , Ambiente , Escocia , Estaciones del AñoRESUMEN
The extent of metal contamination in Sydney residential garden soils was evaluated using data collected during a three-year Macquarie University community science program called VegeSafe. Despite knowledge of industrial and urban contamination amongst scientists, the general public remains under-informed about the potential risks of exposure from legacy contaminants in their home garden environment. The community was offered free soil metal screening, allowing access to soil samples for research purposes. Participants followed specific soil sampling instructions and posted samples to the University for analysis with a field portable X-ray Fluorescence (pXRF) spectrometer. Over the three-year study period, >5200 soil samples, primarily from vegetable gardens, were collected from >1200 Australian homes. As anticipated, the primary soil metal of concern was lead; mean concentrations were 413 mg/kg (front yard), 707 mg/kg (drip line), 226 mg/kg (back yard) and 301 mg/kg (vegetable garden). The Australian soil lead guideline of 300 mg/kg for residential gardens was exceeded at 40% of Sydney homes, while concentrations >1000 mg/kg were identified at 15% of homes. The incidence of highest soil lead contamination was greatest in the inner city area with concentrations declining towards background values of 20-30 mg/kg at 30-40 km distance from the city. Community engagement with VegeSafe participants has resulted in useful outcomes: dissemination of knowledge related to contamination legacies and health risks; owners building raised beds containing uncontaminated soil and in numerous cases, owners replacing all of their contaminated soil.
Asunto(s)
Monitoreo del Ambiente , Jardinería , Metales Pesados/análisis , Contaminantes del Suelo/análisis , Suelo/química , Verduras , Australia , Ciudades , Contaminación Ambiental/análisis , Humanos , Plomo/análisis , Medición de RiesgoRESUMEN
Vacuolar H(+)-ATPase (V-H(+)-ATPase) has been proved to be of importance in maintenance of ion homeostasis inside plant cells under NaCl stress. In this study, the expression levels and salt-tolerate function of V-H(+)-ATPase genes were investigated in the roots and leaves of a halotolerate peppermint (Mentha × piperita L.) Keyuan-1 treated with different concentrations of NaCl. Results showed that the expressions of V-H(+)-ATPase in the transcriptional, protein and activity levels were significantly enhanced in the halotolerate peppermint Keyuan-1 compared to the wild-type (WT) peppermint under 50, 100, and 150 mM NaCl treatment. Moreover, inhibition experiments exhibited that V-H(+)-ATPase activity played vital roles in the salt tolerance of peppermint Keyuan-1 to 150 mM NaCl stress through increasing the vacuolar H(+) pumping activity and Na(+) compartmentalization capacity. Furthermore, results of Western blots showed that the activity of a mitogen-activated protein kinase (MAPK) was significantly increased under different concentrations of NaCl in the halotolerate peppermint Keyuan-1, which was much higher than that of WT peppermint. Further experiments with inhibitors suggested that this MAPK protein was responsible for the enhanced expression of V-H(+)-ATPase in the halotolerate peppermint Keyuan-1. In response to NaCl stress, increase of cytoplasmic calcium concentration ([Ca(2+)]cyt) occurred upstream of MAPK activation in the halotolerate peppermint Keyuan-1. In all, these findings demonstrated that increased V-H(+)-ATPase activity was positively correlated with the enhanced salt tolerance in the halotolerate peppermint Keyuan-1, providing the theoretic basis for the further development and utilization of peppermint in saline areas.
Asunto(s)
Mentha piperita/enzimología , Proteínas de Plantas/fisiología , Raíces de Plantas/enzimología , ATPasas de Translocación de Protón Vacuolares/fisiología , Adaptación Fisiológica , Activación Enzimática , Concentración de Iones de Hidrógeno , Sistema de Señalización de MAP Quinasas , Hojas de la Planta/enzimología , Tolerancia a la Sal , Plantas Tolerantes a la SalRESUMEN
Peppermint (Mentha × piperita L.) is an important and commonly used flavoring agent worldwide, and salinity is a major stress that limits plant growth and reduces crop productivity. This work demonstrated the metabolic responses of essential oil production including the yield and component composition, gene expression, enzyme activity, and protein activation in a salt-tolerant peppermint Keyuan-1 with respect to NaCl stress. Our results showed that Keyuan-1 maintained normal growth and kept higher yield and content of essential oils under NaCl stress than wild-type (WT) peppermint.Gas chromatography-mass spectrometry (GC-MS) and qPCR results showed that compared to WT seedlings, a 150-mM NaCl stress exerted no obvious changes in essential oil composition, transcriptional level of enzymes related to essential oil metabolism, and activity of pulegone reductase (Pr) in Keyuan-1 peppermint which preserved the higher amount of menthol and menthone as well as the lower content of menthofuran upon the 150-mM NaCl stress. Furthermore, it was noticed that a mitogen-activated protein kinase (MAPK) protein exhibited a time-dependent activation in the Keyuan-1 peppermint and primarily involved in the modulation of the essential oil metabolism in the transcript and enzyme levels during the 12-day treatment of 150 mM NaCl. In all, our data elucidated the effect of NaCl on metabolic responses of essential oil production, and demonstrated the MAPK-dependent regulation mechanism of essential oil biosynthesis in the salt-tolerant peppermint, providing scientific basis for the economic and ecological utilization of peppermint in saline land.
Asunto(s)
Mentha piperita/enzimología , Mentha piperita/crecimiento & desarrollo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Aceites Volátiles/metabolismo , Tolerancia a la Sal/efectos de los fármacos , Cloruro de Sodio/farmacología , Estrés Fisiológico/efectos de los fármacos , Western Blotting , Activación Enzimática/efectos de los fármacos , Flavonoides/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Genes de Plantas , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/genética , Mentha piperita/efectos de los fármacos , Mentha piperita/genética , Metabolómica , Monoterpenos/farmacología , Aceites Volátiles/química , Desarrollo de la Planta/efectos de los fármacos , Tolerancia a la Sal/genética , Estrés Fisiológico/genética , Transcripción Genética/efectos de los fármacosRESUMEN
Trichoderma afroharzianum is one of the best characterized Trichoderma species, and strains have been utilized as plant disease suppressive inoculants. In contrast, Trichoderma gamsii has only recently been described, and there is limited knowledge of its disease suppressive efficacies. Comparative studies of changes in gene expression during interactions of these species with their target plant pathogens will provide fundamental information on pathogen antibiosis functions. In the present study, we used complementary DNA amplified fragment length polymorphism (cDNA-AFLP) analysis to investigate changes in transcript profiling of T. afroharzianum strain LTR-2 and T. gamsii strain Tk7a during in vitro interactions with plant pathogenic Rhizoctonia solani and Pythium irregulare. Considerable differences were resolved in the overall expression profiles of strains LTR-2 and Tk7a when challenged with either plant pathogen. In strain LTR-2, previously reported mycoparasitism-related genes such as chitinase, polyketide synthase, and non-ribosomal peptide synthetase were found to be differentially expressed. This was not so for strain Tk7a, with the only previously reported antibiosis-associated genes being small secreted cysteine-rich proteins. Although only one differentially expressed gene was common to both strains LTR-2 and Tk7a, numerous genes reportedly associated with pathogen antibiosis processes were differentially expressed in both strains, including degradative enzymes and membrane transport proteins. A number of novel potential antibiosis-related transcripts were found from strains LTR-2 and Tk7a and remain to be identified. The expression kinetics of 20 Trichoderma (10 from strain LTR-2, 10 from strain Tk7a) transcript-derived fragments (TDFs) were quantified by quantitative reverse transcription PCR (RT-qPCR) at pre- and post-mycelia contact stages of Trichoderma-prey interactions, thereby confirming differential gene expression. Collectively, this research is providing information to elucidate the antibiosis mechanisms and disease suppressive activities of T. afroharzianum and T. gamsii against soilborne fungal and oomycete plant pathogens.
Asunto(s)
Antibiosis , Pythium/fisiología , Rhizoctonia/fisiología , Trichoderma/fisiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulación Fúngica de la Expresión Génica , Enfermedades de las Plantas/microbiología , TranscriptomaRESUMEN
Determining which demographic and ecological parameters contribute to variation in population growth rate is crucial to understanding the dynamics of declining populations. This study aimed to evaluate the magnitude and mechanisms of an apparent major decline in an Atlantic Puffin Fratercula arctica population. This was achieved using a 27-year dataset to estimate changes in population size and in two key demographic rates: adult survival and breeding success. Estimated demographic variation was then related to two ecological factors hypothesised to be key drivers of demographic change, namely the abundance of the main predator at the study site, the Great Skua Stercorarius skua, and Atlantic Puffin chick food supply, over the same 27-year period. Using a population model, we assessed whether estimated variation in adult survival and reproductive success was sufficient to explain the population change observed. Estimates of Atlantic Puffin population size decreased considerably during the study period, approximately halving, whereas Great Skua population estimates increased, approximately trebling. Estimated adult Atlantic Puffin survival remained high across all years and did not vary with Great Skua abundance; however, Atlantic Puffin breeding success and quantities of fish prey brought ashore by adults both decreased substantially through the period. A population model combining best possible demographic parameter estimates predicted rapid population growth, at odds with the long-term decrease observed. To simulate the observed decrease, population models had to incorporate low immature survival, high immature emigration, or increasingly high adult non-breeding rates. We concluded that reduced recruitment of immatures into the breeding population was the most likely cause of population decrease. This study showed that increase in the size of a predator population does not always impact on the survival of adult prey and that reduced recruitment can be a crucial determinant of seabird population size but can easily go undetected.
Asunto(s)
Charadriiformes/fisiología , Animales , Femenino , Cadena Alimentaria , Masculino , Dinámica Poblacional , Conducta Predatoria , Reproducción , Tasa de Supervivencia , Reino UnidoRESUMEN
Trichoderma harzianum is an important commercial biocontrol fungal agent. The temperature has been shown to be an important parameter and strain-specific to the mycelia growth of fungi, but less report makes the known of the mechanisms in T. harzianum. In our study, a 6-h treatment of heat increased the thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) concentration in mycelia to 212 and 230 % the level of the control, respectively. The exogenous NO donor sodium nitroprusside (150 µM) reduced the TBARS concentration to 53 % of that under heat stress (HS). At the same time, the NO-specific scavenger at 250 µM, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-1-oxyl-3-oxide, prevented the exogenous NO-relieved TBARS accumulation under HS. The increased NO concentration under HS was reduced 41 % by the NO synthase (NOS) inhibitor L-N(G)-nitroarginine methyl ester, but not the nitrate reductase (NR) inhibitor tungstate. Our study exhibited that NO can protect the mycelia of T. harzianum from HS and reduce the oxidative damage by enhancing the activity of NOS and NR.
Asunto(s)
Calor , Micelio/metabolismo , Micelio/efectos de la radiación , Óxido Nítrico/metabolismo , Estrés Oxidativo , Trichoderma/metabolismo , Trichoderma/efectos de la radiación , Micelio/enzimología , Nitrato-Reductasa/metabolismo , Óxido Nítrico Sintasa/metabolismo , Trichoderma/enzimologíaRESUMEN
PURPOSE: The goal of this study is to increase patient safety in parallel transmission (pTx) MRI systems. A major concern in these systems is radiofrequency-induced tissue heating, which can be avoided by specific absorption rate (SAR) prediction and SAR monitoring before and during the scan. METHODS: In this novel comprehensive safety concept, the SAR is predicted prior to the scan based on precalculated fields obtained from electromagnetic simulations on different body models. The radiofrequency fields and the global and local SAR are supervised in real time during the scan. This concept is integrated into a 3 T pTx MR scanner and validated experimentally. RESULTS: Phantom and in vivo experiments successfully validated the basic feasibility of the real-time SAR supervision concept. Supervising the SAR minimizes SAR overestimation. Monitoring the radiofrequency fields allows the detection of unsafe radiofrequency situations for the patient, which a SAR supervision system alone cannot detect. CONCLUSION: This study demonstrates safe scanning in a pTx system. This new safety concept is also applicable for field strengths above 3 T and represents an important step toward safe operation of pTx systems.
Asunto(s)
Seguridad de Equipos/instrumentación , Imagen por Resonancia Magnética/instrumentación , Radiometría/instrumentación , Procesamiento de Señales Asistido por Computador/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Campos Magnéticos , Dosis de RadiaciónRESUMEN
Natural biological suppression of soil-borne diseases is a function of the activity and composition of soil microbial communities. Soil microbe and phytopathogen interactions can occur prior to crop sowing and/or in the rhizosphere, subsequently influencing both plant growth and productivity. Research on suppressive microbial communities has concentrated on bacteria although fungi can also influence soil-borne disease. Fungi were analyzed in co-located soils 'suppressive' or 'non-suppressive' for disease caused by Rhizoctonia solani AG 8 at two sites in South Australia using 454 pyrosequencing targeting the fungal 28S LSU rRNA gene. DNA was extracted from a minimum of 125 g of soil per replicate to reduce the micro-scale community variability, and from soil samples taken at sowing and from the rhizosphere at 7 weeks to cover the peak Rhizoctonia infection period. A total of â¼ 994,000 reads were classified into 917 genera covering 54% of the RDP Fungal Classifier database, a high diversity for an alkaline, low organic matter soil. Statistical analyses and community ordinations revealed significant differences in fungal community composition between suppressive and non-suppressive soil and between soil type/location. The majority of differences associated with suppressive soils were attributed to less than 40 genera including a number of endophytic species with plant pathogen suppression potentials and mycoparasites such as Xylaria spp. Non-suppressive soils were dominated by Alternaria, Gibberella and Penicillum. Pyrosequencing generated a detailed description of fungal community structure and identified candidate taxa that may influence pathogen-plant interactions in stable disease suppression.