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1.
Glob Chang Biol ; 30(5): e17298, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38712640

RESUMEN

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.


Asunto(s)
Cambio Climático , Productos Agrícolas , Zea mays , Productos Agrícolas/crecimiento & desarrollo , Zea mays/crecimiento & desarrollo , América del Norte , Europa (Continente) , Grano Comestible/crecimiento & desarrollo , Agricultura/métodos , Biodiversidad , Producción de Cultivos/métodos
2.
Mol Ecol ; 32(23): 6696-6709, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36799015

RESUMEN

The spread of nonindigenous species by shipping is a large and growing global problem that harms coastal ecosystems and economies and may blur coastal biogeographical patterns. This study coupled eukaryotic environmental DNA (eDNA) metabarcoding with dissimilarity regression to test the hypothesis that ship-borne species spread homogenizes port communities. We first collected and metabarcoded water samples from ports in Europe, Asia, Australia and the Americas. We then calculated community dissimilarities between port pairs and tested for effects of environmental dissimilarity, biogeographical region and four alternative measures of ship-borne species transport risk. We predicted that higher shipping between ports would decrease community dissimilarity, that the effect of shipping would be small compared to that of environment dissimilarity and shared biogeography, and that more complex shipping risk metrics (which account for ballast water and stepping-stone spread) would perform better. Consistent with our hypotheses, community dissimilarities increased significantly with environmental dissimilarity and, to a lesser extent, decreased with ship-borne species transport risks, particularly if the ports had similar environments and stepping-stone risks were considered. Unexpectedly, we found no clear effect of shared biogeography, and that risk metrics incorporating estimates of ballast discharge did not offer more explanatory power than simpler traffic-based risks. Overall, we found that shipping homogenizes eukaryotic communities between ports in predictable ways, which could inform improvements in invasive species policy and management. We demonstrated the usefulness of eDNA metabarcoding and dissimilarity regression for disentangling the drivers of large-scale biodiversity patterns. We conclude by outlining logistical considerations and recommendations for future studies using this approach.


Asunto(s)
ADN Ambiental , Ecosistema , ADN Ambiental/genética , Navíos , Biodiversidad , Agua , Monitoreo del Ambiente , Código de Barras del ADN Taxonómico
3.
Appl Environ Microbiol ; 87(12): e0313220, 2021 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-33811028

RESUMEN

Root-associated microbes are key players in plant health, disease resistance, and nitrogen (N) use efficiency. It remains largely unclear how the interplay of biological and environmental factors affects rhizobiome dynamics in agricultural systems. In this study, we quantified the composition of rhizosphere and bulk soil microbial communities associated with maize (Zea mays L.) and soybean (Glycine max L.) in a long-term crop rotation study under conventional fertilization and low-N regimes. Over two growing seasons, we evaluated the effects of environmental conditions and several treatment factors on the abundance of rhizosphere- and soil-colonizing microbial taxa. Time of sampling, host plant species, and N fertilization had major effects on microbiomes, while no effect of crop rotation was observed. Using variance partitioning as well as 16S sequence information, we further defined a set of 82 microbial genera and functional taxonomic groups at the subgenus level that show distinct responses to treatment factors. We identified taxa that are highly specific to either maize or soybean rhizospheres, as well as taxa that are sensitive to N fertilization in plant rhizospheres and bulk soil. This study provides insights to harness the full potential of soil microbes in maize and soybean agricultural systems through plant breeding and field management. IMPORTANCE Plant roots are colonized by large numbers of microbes, some of which may help the plant acquire nutrients and fight diseases. Our study contributes to a better understanding of root-colonizing microbes in the widespread and economically important maize-soybean crop rotation system. The long-term goal of this research is to optimize crop plant varieties and field management to create the best possible conditions for beneficial plant-microbe interactions to occur. These beneficial microbes may be harnessed to sustainably reduce dependency on pesticides and industrial fertilizer. We identify groups of microbes specific to the maize or to the soybean host and microbes that are sensitive to nitrogen fertilization. These microbes represent candidates that may be influenced through plant breeding or field management, and future research will be directed toward elucidating their roles in plant health and nitrogen usage.


Asunto(s)
Agricultura/métodos , Glycine max/efectos de los fármacos , Microbiota/efectos de los fármacos , Nitrógeno/farmacología , Rizosfera , Zea mays/efectos de los fármacos , Fertilizantes , Estaciones del Año , Microbiología del Suelo , Glycine max/microbiología , Zea mays/microbiología
4.
J Environ Manage ; 285: 112097, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33578214

RESUMEN

Agricultural production is a major source of carbon dioxide (CO2) and nitrous oxide (N2O) globally. The effects of conservation practices on soil CO2 and N2O emissions remain a high degree of uncertainty. In this study, soil CO2 and N2O emissions under different residue and tillage practices in an irrigated, continuous corn system, were investigated using the Root Zone Water Quality Model (RZWQM2). Combinations of no/high stover removal (NR and HR, respectively) and no-till/conventional tillage (NT and CT, respectively) field experiments were tested over the four crop-years (Apr. 2011-Apr. 2015). The model was calibrated using the NRCT, and validated with other treatments. The simulation results showed that soil volumetric water content (VWC) in the NR treatments (i.e., NRCT and NRNT) was 1.3%-1.9% higher than that in the HR treatments (i.e., HRCT and HRNT) averaged across the four years. A higher amount of CO2 and N2O emissions were simulated in the NRCT across the four years (annual average: 7034 kg C/ha/yr for CO2 and 3.8 kg N/ha/yr for N2O), and lower emissions were in the HRNT (annual average: 6329 kg C/ha/yr and 3.7 kg N/ha/yr for N2O). A long-term simulation (2001-2015) suggested that the CO2 and N2O emissions were closely correlated with the stover removal degree (SRD), tillage, VWC, soil temperature (ST), years in management (Y), and fertilizer application. Stover and tillage practices had cumulative effects on CO2 emissions. The simulated annual CO2 emissions in 1st year from NRCT, NRNT, and HRCT were 7.8%, 0.0%, and 7.7% higher than that from HRNT, respectively; then the emissions in 15th year were 63.6%, 47.7%, and 29.1% higher, respectively. Meanwhile, there were no cumulative effects on N2O emissions. The results also demonstrated that the RZWQM2 is a promising tool for evaluating the long-term effects of CO2 and N2O emissions on different conservation practices.


Asunto(s)
Gases de Efecto Invernadero , Agricultura , Dióxido de Carbono/análisis , Fertilizantes/análisis , Óxido Nitroso/análisis , Suelo , Calidad del Agua , Zea mays
5.
J Cardiovasc Magn Reson ; 21(1): 52, 2019 08 08.
Artículo en Inglés | MEDLINE | ID: mdl-31391061

RESUMEN

BACKGROUND: Cardiovascular magnetic resonance (CMR) angiography (CMRA) is an important non-invasive imaging tool for congenital heart disease (CHD) and aortopathy patients. The conventional 3D balanced steady-state free precession (bSSFP) sequence is often confounded by imaging artifacts. We sought to compare the respiratory navigated and electrocardiogram (ECG) gated modified Dixon (mDixon) CMRA sequence to conventional non-gated dynamic multi-phase contrast enhanced CMRA (CE-CMRA) and bSSFP across a variety of diagnoses. METHODS: We included 24 patients with CHD or aortopathy with CMR performed between September 2017 to December 2017. Each patient had undergone CE-CMRA, followed by a bSSFP and mDixon angiogram. Patients with CMR-incompatible implants or contraindications to contrast were excluded. The studies were rated according to image quality at a scale from 1 (poor) to 4 (excellent) based on diagnostic adequacy, artifact burden, vascular border delineation, myocardium-blood pool contrast, and visualization of pulmonary and systemic veins and coronaries. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and quantitative vascular measurements were compared between the two gated sequences. Bland-Altman plots were generated to compare paired measures. RESULTS: All scans were diagnostically adequate. Mean (SD) quality scores were 3.4 (0.7) for the mDixon, 3.2 (0.5) for the bSSFP and 3.4 (0.5) for the CE-CMRA. Qualitatively, the intracardiac anatomy and myocardium-blood pool definition were better in the bSSFP; however, mDixon images showed enhanced vessel wall sharpness with less blurring surrounding the anatomical borders distally. Coronary origins were identified in all cases. Pulmonary veins were visualized in 92% of mDixon sequences, 75% of bSSFP and 96% of CE-CMRA. Similarly, neck veins were identified in 92, 83 and 96% respectively. Artifacts prevented vascular measurement in 6/192 (3%) and 4/192 (2%) of total vascular measurements for the mDixon and bSSFP, respectively. However, the size of signal void and field distortion were significantly worse in the latter, particularly for flow and metal induced artifacts. CONCLUSION: In patients with congenital heart disease, ECG gated mDixon angiography yields high fidelity vascular images including better delineation of head and neck vasculature and pulmonary veins and fewer artifacts than the comparable bSSFP sequence. It should be considered as the preferred strategy for successful CHD imaging in patients with valve stenosis, vascular stents, or metallic implants.


Asunto(s)
Aorta/diagnóstico por imagen , Enfermedades de la Aorta/diagnóstico por imagen , Técnicas de Imagen Sincronizada Cardíacas , Vasos Coronarios/diagnóstico por imagen , Electrocardiografía , Cardiopatías Congénitas/diagnóstico por imagen , Imagenología Tridimensional , Angiografía por Resonancia Magnética , Adolescente , Adulto , Artefactos , Niño , Preescolar , Medios de Contraste/administración & dosificación , Femenino , Humanos , Lactante , Masculino , Meglumina/administración & dosificación , Compuestos Organometálicos/administración & dosificación , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Estudios Retrospectivos , Adulto Joven
6.
J Fish Dis ; 42(1): 63-74, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30324720

RESUMEN

Bonamia spp. parasites threaten flat oyster (Ostrea spp.) farming worldwide. Understanding test performance is important for designing surveillance and interpreting diagnostic results. Following a pilot survey which found low Bonamia sp. intensity in farmed Ostrea angasi, we tested further oysters (n = 100-150) from each of three farms for Bonamia sp. using heart smear, histology and qPCR. We used a Bayesian Latent Class Model to assess diagnostic sensitivity (DSe) and specificity (DSp) of these tests individually or in combination, and to assess prevalence. Histology was the best individual test (DSe 0.76, DSp 0.93) compared to quantitative polymerase chain reaction (qPCR) (DSe 0.69, DSp 0.93) and heart smear (DSe 0.61, DSp 0.60). Histology combined with qPCR and defining a positive from either test as an infected case maximized test performance (DSe 0.91, DSp 0.88). Prevalence was higher at two farms in a high-density oyster growing region than at a farm cultivating oysters at lower density. Parasite intensities were lower than in New Zealand and European studies, and this is probably contributed to differences in the performance of test when compared to other studies. Understanding diagnostic test performance in different populations can support the development of improved Bonamia surveillance programs.


Asunto(s)
Enfermedades de los Peces/diagnóstico , Enfermedades de los Peces/parasitología , Haplosporidios , Ostrea/parasitología , Infecciones Protozoarias en Animales/diagnóstico , Animales , Acuicultura , Enfermedades de los Peces/epidemiología , Corazón/parasitología , Técnicas Histológicas/veterinaria , Prevalencia , Infecciones Protozoarias en Animales/epidemiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Australia del Sur/epidemiología
7.
J Environ Qual ; 47(4): 704-709, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30025056

RESUMEN

The western US Corn Belt is projected to experience major changes in growing conditions due to climate change over the next 50 to 100 yr. Projected changes include increases in growing season length, number of high temperature stress days and warm nights, and precipitation, with more heavy rainfall events. The impact these changes will have on soil organic carbon (SOC) needs to be estimated and adaptive changes in management developed to sustain soil health and system services. The process-based model CQESTR was used to model changes in SOC stocks (0-30 cm) of continuous corn ( L.) and a corn-soybean [ (L.) Merr.] rotation under disk, chisel, ridge, and no-tillage using projected growing season conditions for the next 50 yr. Input for the model was based on management and harvest records from a long-term tillage study (1986-2015) in eastern Nebraska, and model output was validated using measured changes in SOC from 1999 to 2011 in the study. The validated model was used to estimate changes in SOC over 17 yr under climatic conditions projected for 2065 under two scenarios: (i) crop yields increasing at the observed rate from 1971 to 2016 or (ii) crop yields reduced due to negative effects of increasing temperature. CQESTR estimates of SOC agreed well with measured SOC ( = 0.70, < 0.0001). Validated model simulated changes in SOC under projected climate change differed among the three soil depths (0-7.5, 7.5-15, and 15-30 cm). Summed over the 0- to 30-cm depth, there were significant three-way interactions of year × rotation × yield ( = 0.014) and year × tillage × yield ( < 0.001). As yield increased, SOC increased under no-tillage continuous corn but was unchanged under no-tillage corn-soybean and ridge tillage regardless of cropping system. Under chisel and disk tillage, SOC declined regardless of cropping system. With declining yields SOC decreased regardless of tillage or cropping system. These results highlight the interaction between genetics and management in maintaining yield trends and soil C.


Asunto(s)
Carbono , Cambio Climático , Zea mays , Agricultura , Productos Agrícolas , Suelo/química
8.
Glob Chang Biol ; 23(7): 2848-2862, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28135027

RESUMEN

Over the last 50 years, the most increase in cultivated land area globally has been due to a doubling of irrigated land. Long-term agronomic management impacts on soil organic carbon (SOC) stocks, soil greenhouse gas (GHG) emissions, and global warming potential (GWP) in irrigated systems, however, remain relatively unknown. Here, residue and tillage management effects were quantified by measuring soil nitrous oxide (N2 O) and methane (CH4 ) fluxes and SOC changes (ΔSOC) at a long-term, irrigated continuous corn (Zea mays L.) system in eastern Nebraska, United States. Management treatments began in 2002, and measured treatments included no or high stover removal (0 or 6.8 Mg DM ha-1  yr-1 , respectively) under no-till (NT) or conventional disk tillage (CT) with full irrigation (n = 4). Soil N2 O and CH4 fluxes were measured for five crop-years (2011-2015), and ΔSOC was determined on an equivalent mass basis to ~30 cm soil depth. Both area- and yield-scaled soil N2 O emissions were greater with stover retention compared to removal and for CT compared to NT, with no interaction between stover and tillage practices. Methane comprised <1% of total emissions, with NT being CH4 neutral and CT a CH4 source. Surface SOC decreased with stover removal and with CT after 14 years of management. When ΔSOC, soil GHG emissions, and agronomic energy usage were used to calculate system GWP, all management systems were net GHG sources. Conservation practices (NT, stover retention) each decreased system GWP compared to conventional practices (CT, stover removal), but pairing conservation practices conferred no additional mitigation benefit. Although cropping system, management equipment/timing/history, soil type, location, weather, and the depth to which ΔSOC is measured affect the GWP outcomes of irrigated systems at large, this long-term irrigated study provides valuable empirical evidence of how management decisions can impact soil GHG emissions and surface SOC stocks.


Asunto(s)
Productos Agrícolas , Calentamiento Global , Zea mays/crecimiento & desarrollo , Riego Agrícola , Agricultura , Efecto Invernadero , Óxido Nitroso , Suelo
9.
J Dairy Sci ; 100(8): 6422-6428, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-28551191

RESUMEN

Bovine mastitis costs the dairy industry billions of dollars every year and presents a health challenge in dairy facilities. Immunosuppressive effects of the periparturient period increase the incidence of mastitis. During this time, cattle experience an elevation in circulating cortisol, which reduces polymorphonuclear cell function and ability to clear infection. OmniGen-AF (OMN; Phibro Animal Health, Teaneck, NJ) is an immunomodulatory feed additive that alters gene expression and is used to reduce rates of mastitis. We hypothesized that OMN restores gene expression during periods of immune stress through inhibiting the suppressive effects of glucocorticoid receptor signaling on Toll-like receptor signaling. To test our hypothesis, wild-type (WT) or MyD88 knockout mice were supplemented with OMN and challenged with lipopolysaccharide following dexamethasone (Dex) treatment. Polymorphonuclear cell and macrophage RNA was isolated from intraperitoneal lavages and analyzed for gene expression profiles. Treatment of mice with Dex suppressed expression of l-selectin and CCL5 as compared with phosphate-buffered saline treatment of WT mice. Expression of l-selectin and CCL5 was significantly reduced with Dex treatment in control-fed but not OMN-supplemented WT mice. The protective effect of OMN supplementation on l-selectin expression during Dex treatment was abolished in MyD88 knockout mice. These results suggest that OMN supplementation restores responses of certain genes suppressed by Dex in immune cells in a MyD88-dependent manner. Future research will determine the specific Toll-like receptors, transcription factors, and biochemical properties of OMN that restore gene expression in immunosuppressed cells.


Asunto(s)
Quimiocina CCL5/metabolismo , Dexametasona/farmacología , Selectina L/metabolismo , Factor 88 de Diferenciación Mieloide/metabolismo , Animales , Bovinos , Femenino , Inmunomodulación , Macrófagos , Ratones , Neutrófilos , Receptores Toll-Like
10.
Dis Aquat Organ ; 121(3): 201-209, 2016 10 27.
Artículo en Inglés | MEDLINE | ID: mdl-27786158

RESUMEN

Praziquantel (PZQ) is registered for oral use against Benedenia seriolae infecting Seriola spp. in Japan, but its bitter taste causes poor palatability. Incorporating PZQ in a moist pellet may help mask the flavor to improve intake. Altering delivery, however, may influence efficacy. We assessed the minimum effective concentrations of PZQ in moist pellets delivered by intubation for the monogeneans Zeuxapta seriolae and B. seriolae infecting yellowtail kingfish Seriola lalandi in flow-through tanks. The optimised dose was then evaluated in a sea-cage of S. lalandi to assess feed acceptance and efficacy. During intubation trials, efficacy was assessed as a percent reduction compared to control groups; in the field trial, efficacy was assessed by a percent reduction after treatment. PZQ delivered by intubation at 70 mg kg-1 body weight (BW) for 3 d was 99.7 and 81.7% effective against Z. seriolae and B. seriolae, respectively. Increasing the dose to 120 mg kg-1 BW for 3 d had a similar efficacy against Z. seriolae (98.4%) and increased efficacy against B. seriolae to 89.2%, but partial emesis of the medicated feed was sometimes noted. S. lalandi in a sea-cage at 17°C readily consumed PZQ administered daily in moist pellets at 70 mg kg-1 BW for 3 d (inclusion rate: 5.15 g kg-1), which significantly reduced Z. seriolae and B. seriolae abundance with 99.4 and 81.6% efficacy, respectively. Juvenile B. seriolae were common on the eyes of fish post-treatment which indicates a strategically timed repeat treatment is necessary.


Asunto(s)
Alimentación Animal , Enfermedades de los Peces/parasitología , Praziquantel/uso terapéutico , Trematodos/clasificación , Infecciones por Trematodos/veterinaria , Administración Oral , Animales , Antihelmínticos/administración & dosificación , Antihelmínticos/uso terapéutico , Enfermedades de los Peces/tratamiento farmacológico , Peces , Praziquantel/administración & dosificación , Infecciones por Trematodos/tratamiento farmacológico
11.
Fish Physiol Biochem ; 42(1): 103-9, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26314575

RESUMEN

Regulatory approval is being sought to use praziquantel (PZQ) to treat flukes infecting yellowtail kingfish (YTK), but accurate safety data were not available. We investigated the effect of increased doses or prolonged exposure of orally administered PZQ on YTK by assessing changes in haematological and biochemical characteristics, and mortality. Fish were intubated daily for 3 days with 0, 100, 300 and 500 mg PZQ kg(-1) BW day(-1) or once daily for 9 days at 0 and 100 mg PZQ kg(-1) BW day(-1). Blood was taken 24 h after the cessation of treatment. There was no significant difference between any of the haematological or biochemical indices in YTK treated with PZQ and controls, indicating that PZQ is safe for use at 100 mg PZQ kg(-1) BW day(-1) in YTK and that exposure to high doses or prolonged duration does not have negative effects on the YTK haematological or biochemical parameters we measured.


Asunto(s)
Antihelmínticos/administración & dosificación , Perciformes/sangre , Praziquantel/administración & dosificación , Animales , Antihelmínticos/farmacología , Antihelmínticos/uso terapéutico , Esquema de Medicación , Enfermedades de los Peces/prevención & control , Helmintiasis Animal/prevención & control , Pruebas Hematológicas , Praziquantel/farmacología , Praziquantel/uso terapéutico
12.
Dis Aquat Organ ; 114(3): 263-8, 2015 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-26036833

RESUMEN

Ichthyophthirius multifiliis is a recurring problem in Australian rainbow trout Oncorhynchus mykiss farms and requires strategically timed, repeat treatments for effective management. Sodium percarbonate (SPC) is permitted for use in Australia, with host safety margins based on the toxicity of acute exposures to hydrogen peroxide (HP), the active product released when SPC is added to water. The effects of exposure to HP released by SPC, of repeated doses and of doses exceeding 100 mg l-1 on rainbow trout are unknown. We exposed juvenile rainbow trout (mean weight: 30.5 ± 9 g) to repeated doses of 50, 150 and 250 mg l-1 SPC for 1 h on Days 1, 2, 7 and 8 of a treatment regime. The effect of SPC was assessed by histological evaluation of structural changes in gill tissue. Survival was 100% in all groups, but some fish exposed to 250 mg l-1 SPC displayed impaired swimming performance, and on Day 9 after the final treatment, oedema was present in 9.8% of lamella, which was significantly higher than the mean occurrence of 1.7, 4.2 and 1.3% in fish treated with 0, 50 and 150 mg l-1 SPC, respectively. These changes resolved within 24 h of the cessation of treatment. We conclude that SPC is safe to use on rainbow trout in doses of ≤150 mg l-1 at 17°C, however caution is advised at doses approaching 250 mg l-1. Water temperature, fish age, fish size and maturity, intensity of parasite infection and stocking density could alter the sensitivity of rainbow trout to SPC treatments.


Asunto(s)
Antiparasitarios/efectos adversos , Carbonatos/efectos adversos , Enfermedades de los Peces/inducido químicamente , Branquias/efectos de los fármacos , Oncorhynchus mykiss , Animales , Australia , Carbonatos/administración & dosificación , Relación Dosis-Respuesta a Droga , Enfermedades de los Peces/patología , Branquias/patología , Estrés Oxidativo
13.
Folia Parasitol (Praha) ; 622015 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-25960557

RESUMEN

Ichthyophthirius multifiliis Fouquet, 1876, a ciliate parasite, is a cosmopolitan and problematic parasite of cultured freshwater fish. Each geographical isolate of I. multifiliis has variations in life cycle timing under different abiotic water conditions, such as temperature and salinity. We assessed the effects of salinity and temperature on the development and the preferred settlement site of a temperate Australian isolate of I. multifiliis. The time until theront release was significantly different between each temperature; development time was longest at 5 °C with a mean time of 189 h and decreased to a mean time of 11.7 h at 30 °C. At 5 °C our isolate produced a mean of 267 theronts per tomont, which increased to a mean of 493 theronts at 25 °C and reduced to a mean of 288 theronts at 30 °C. Theront length showed an inverse relationship to temperature; mean length was 62 µm at 5 °C and 41 µm at 30 °C. Our isolate reproduced faster at all temperatures and a greater sensitivity to salinity than all reported profiles for temperate isolates. Parasite abundance was highest on the dorsal region of the fish. An accurate understanding of temperature-life cycle information and optimal region to sample for surveillance will aid in the development of specific management plans for the Australian isolate of I. multifiliis, facilitating the strategic timing of treatments.

14.
Parasitol Res ; 113(9): 3251-8, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24948105

RESUMEN

Ichthyophthirius multifiliis Fouquet, 1876, a ciliate protozoan, is a common cosmopolitan parasite of freshwater teleosts and is a recurring problem during the summer months on Australian rainbow trout Oncorhynchus mykiss (Walbaum, 1792) farms. Preventative strategies include increasing water flow and filtration, but when an infection is established, chemical intervention is often required. Formalin (FOR) has been traditionally used on Australian trout farms as a treatment for I. multifiliis. Treatment using sodium percarbonate (SPC) that releases hydrogen peroxide when dissolved is being implemented on a number of farms. To assess anecdotal reports of low efficacy we evaluated 1 h exposures of FOR and SPC at 12 °C and 17 °C in both hard and soft water against free-living stages of I. multifiliis. Each free-living stage were exposed to FOR and SPC in vitro; theronts were exposed to 8, 16, 32 or 64 mg/l SPC or FOR every 15 min, for a maximum of 6 h, and the number of live theronts at each time point was recorded. Prototomonts and tomocysts were exposed to 64, 128, 256 and 512 mg/l SPC and 16, 32, 64 and 128 mg/l FOR for 1 h, incubated, with the percentage viability and the number of theronts produced recorded. Theronts were more sensitive to treatment than tomonts, and prototomonts were more sensitive to treatment than tomocysts. FOR and SPC killed all theronts within 15 min at 64 mg/l at both temperatures. FOR was effective against all prototomonts at ≥64 mg/l at both temperatures and was effective against all tomocysts at 128 mg/l at 17 °C but did not achieve complete mortality in any doses tested at 12 °C. SPC was effective against prototomonts and tomocysts at 64 m/l at 17 °C but required ≥256 mg/l at 12 °C. These results can be used to aid development of specific treatment strategies for the management of I. multifiliis on Australian rainbow trout farms.


Asunto(s)
Carbonatos/farmacología , Infecciones por Cilióforos/veterinaria , Cilióforos/clasificación , Enfermedades de los Peces/tratamiento farmacológico , Formaldehído/farmacología , Oncorhynchus mykiss/parasitología , Animales , Antiparasitarios/administración & dosificación , Antiparasitarios/farmacología , Carbonatos/administración & dosificación , Cilióforos/efectos de los fármacos , Infecciones por Cilióforos/tratamiento farmacológico , Relación Dosis-Respuesta a Droga , Enfermedades de los Peces/parasitología , Formaldehído/administración & dosificación , Peróxido de Hidrógeno/farmacología , Hymenostomatida/efectos de los fármacos , Temperatura
15.
J Environ Qual ; 53(1): 66-77, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37889790

RESUMEN

Fall-planted cover crop (CC) within a continuous corn (Zea mays L.) system offers potential agroecosystem benefits, including mitigating the impacts of increased temperature and variability in precipitation patterns. A long-term simulation using the Decision Support System for Agrotechnology Transfer model was made to assess the effects of cereal rye (Secale cereale L.) on no-till continuous corn yield and soil properties under historical (1991-2020) and projected climate (2041-2070) in eastern Nebraska. Local weather data during the historical period were used, while climate change projections were based on the Canadian Earth System Model 2 dynamically downscaled using the Canadian Centre for Climate Modelling and Analysis Regional Climate Model 4 under two representative concentration pathways (RCP), namely, RCP4.5 and RCP8.5. Simulations results indicated that CC impacts on corn yield were nonsignificant under historical and climate change conditions. Climate change created favorable conditions for CC growth, resulting in an increase in biomass. CC reduced N leaching under climate change scenarios compared to an average reduction of 60% (7 kg ha- 1 ) during the historical period. CC resulted in a 6% (27 mm) reduction in total water in soil profile (140 cm) and 22% (27 mm) reduction in plant available water compared to no cover crop during historical period. CC reduced cumulative seasonal surface runoff/soil evaporation and increased the rate of soil organic carbon buildup. This research provides valuable information on how changes in climate can impact the performance of cereal rye CC in continuous corn production and should be scaled to wider locations and CC species.


Asunto(s)
Agricultura , Suelo , Agricultura/métodos , Zea mays , Nebraska , Carbono/análisis , Productos Agrícolas , Canadá , Grano Comestible/química , Grano Comestible/metabolismo , Cambio Climático , Secale/metabolismo , Agua
16.
Carcinogenesis ; 34(5): 1044-50, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23354305

RESUMEN

Epidemiological studies of underground miners suggested that occupational exposure to radon causes lung cancer with squamous cell carcinoma (SCC) as the predominant histological type. However, the genetic determinants for susceptibility of radon-induced SCC in miners are unclear. Double-strand breaks induced by radioactive radon daughters are repaired primarily by non-homologous end joining (NHEJ) that is accompanied by the dynamic changes in surrounding chromatin, including nucleosome repositioning and histone modifications. Thus, a molecular epidemiological study was conducted to assess whether genetic variation in 16 genes involved in NHEJ and related histone modification affected susceptibility for SCC in radon-exposed former miners (267 SCC cases and 383 controls) from the Colorado plateau. A global association between genetic variation in the haplotype block where SIRT1 resides and the risk for SCC in miners (P = 0.003) was identified. Haplotype alleles tagged by the A allele of SIRT1 rs7097008 were associated with increased risk for SCC (odds ratio = 1.69, P = 8.2 × 10(-5)) and greater survival in SCC cases (hazard ratio = 0.79, P = 0.03) in miners. Functional validation of rs7097008 demonstrated that the A allele was associated with reduced gene expression in bronchial epithelial cells and compromised DNA repair capacity in peripheral lymphocytes. Together, these findings substantiate genetic variation in SIRT1 as a risk modifier for developing SCC in miners and suggest that SIRT1 may also play a tumor suppressor role in radon-induced cancer in miners.


Asunto(s)
Carcinoma de Células Escamosas/genética , Neoplasias Pulmonares/genética , Minería , Neoplasias Inducidas por Radiación/genética , Enfermedades Profesionales/genética , Sirtuina 1/genética , Uranio/envenenamiento , Alelos , Carcinoma de Células Escamosas/etiología , Estudios de Casos y Controles , Colorado , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Haplotipos , Humanos , Neoplasias Pulmonares/etiología , Linfocitos/metabolismo , Masculino , Persona de Mediana Edad , Neoplasias Inducidas por Radiación/etiología , Enfermedades Profesionales/etiología , Exposición Profesional/efectos adversos , Polimorfismo de Nucleótido Simple , Radón/envenenamiento
17.
Phys Chem Chem Phys ; 15(12): 4205-13, 2013 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-23264962

RESUMEN

Noble metal particles allow enhanced interaction with light and efficient light to heat conversion. In the present paper, we report on non-linear optical spectroscopy of individual gold crystalline platelets and address two of the energy relaxation steps following optical excitation of the metallic nano-objects. In particular, at short timescales we show that optical excitation yields intense two-photon photoluminescence at particular locations of the gold platelets. Our experimental results are interpreted with numerical simulations based on the Green Dyadic Method. Subsequent conversion from optical to thermal energy triggers acoustic vibrations that modulate the optical response of the nano-object on a 10 ps-100 ps timescale. We address the different contributions to the damping of the associated mechanical oscillations focusing on the high frequency thickness vibrations (100 GHz) of these nanometer-thin metallic structures.

18.
Dis Aquat Organ ; 105(3): 253-7, 2013 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-23999709

RESUMEN

We used a published sub-sampling method for estimating the abundance of the monogenean Lepidotrema bidyana, a gill parasite of silver perch Bidyanus bidyanus, and determined that it also accurately predicts parasite abundance post-treatment. Post-treatment parasite abundance estimates based on the number of parasites on the first left posterior hemibranch were compared to actual counts on fish after bath and oral treatment trials with praziquantel and fenbendazole. Post-treatment parasite abundance estimates were significantly correlated to real counts of all individual hemibranchs, accurately predicting the parasite abundance on an individual host. There was no significant difference in the post-treatment parasite abundance between individual hemibranchs, however, indicating that the treatment affected L. bidyana abundance on each hemibranch unequally. Use of this method is ineffective at predicting post-treatment abundance; however, it accurately predicts the remaining parasite abundance, aiding evaluation of treatment efficacy, while reducing post-treatment sampling time or facilitating larger sample sizes.


Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Peces/parasitología , Perciformes , Platelmintos , Infecciones por Trematodos/veterinaria , Animales , Fenbendazol/uso terapéutico , Enfermedades de los Peces/tratamiento farmacológico , Praziquantel/uso terapéutico , Reproducibilidad de los Resultados , Infecciones por Trematodos/tratamiento farmacológico , Infecciones por Trematodos/parasitología
19.
Sci Total Environ ; 879: 162906, 2023 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-36934923

RESUMEN

Despite the extensive application of the Soil and Water Assessment Tool (SWAT) for water quality modeling, its ability to simulate soil inorganic nitrogen (SIN) dynamics in agricultural landscapes has not been directly verified. Here, we improved and evaluated the SWAT-Carbon (SWAT-C) model for simulating long-term (1984-2020) dynamics of SIN for 40 cropping system treatments in the U.S. Midwest. We added one new nitrification and two new denitrification algorithms to the default SWAT version, resulting in six combinations of nitrification and denitrification options with varying performance in simulating SIN. The combination of the existing nitrification method in SWAT and the second newly added denitrification method performed the best, achieving R, NSE, PBIAS, and RMSE of 0.63, 0.29, -4.7 %, and 16.0 kg N ha-1, respectively. This represents a significant improvement compared to the existing methods. In general, the revised SWAT-C model's performance was comparable to or better than other agroecosystem models tested in previous studies for assessing the availability of SIN for plant growth in different cropping systems. Sensitivity analysis showed that parameters controlling soil organic matter decomposition, nitrification, and denitrification were most sensitive for SIN simulation. Using SWAT-C for improved prediction of plant-available SIN is expected to better inform agroecosystem management decisions to ensure crop productivity while minimizing the negative environmental impacts caused by fertilizer application.

20.
Dis Aquat Organ ; 100(1): 51-7, 2012 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-22885513

RESUMEN

We developed a rapid effective method for accurate estimation of intensity for the monogenean Lepidotrema bidyana, a gill parasite of silver perch Bidyanus bidyanus. This parasite requires monitoring because high-intensity infections reduce host growth and can lead to secondary bacterial and fungal infections. The most accurate method for counting L. bidyana was visual examination of fresh gills. There was a significant relationship between fish size and parasite intensity; however, there was no significant relationship between fish condition and parasite intensity. Parasite intensity estimates were generated by using the mean intensity of worms on the posterior hemibranch on the first left gill arch, compared to the total mean intensity of worms on all hemibranchs. Estimates were validated by predicting L. bidyana intensity from a random sample of silver perch obtained from aquaculture ponds. Parasite intensity estimates correlated strongly to real counts, and this method can be used to accurately predict parasite intensity on an individual host, and thus represents an improvement over previous methods.


Asunto(s)
Enfermedades de los Peces/parasitología , Percas/parasitología , Platelmintos , Infecciones por Trematodos/veterinaria , Crianza de Animales Domésticos/métodos , Animales , Acuicultura , Branquias/parasitología , Interacciones Huésped-Parásitos , Especificidad de la Especie , Infecciones por Trematodos/parasitología
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