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排序方式: 共有361条查询结果,搜索用时 31 毫秒
1.
Jessica Fry Juan Pérez Casanova Lynn Lush Andy Walsh Cyr Couturier 《Journal of aquatic animal health》2015,27(1):57-64
The direct exposure of fish eggs to ozonated water has generated interest as a means of ensuring pathogen-free eggs without the use of harsh chemicals. However, there are numerous knowledge gaps, including safe contact times, exposure levels, and potential long-term effects on aquaculture species in both freshwater and seawater. The effect of different ozone (O3) doses (0.5–1.0, 1.5–2.0, and 2.5–3.0 mg of O3/L for 90 s) on recently fertilized eggs of Atlantic Cod Gadus morhua and eyed eggs of Atlantic Salmon Salmo salar and Rainbow Trout Oncorhynchus mykiss was evaluated in comparison with the effects of two commercial disinfectants: Perosan (0.004 mg/L) and Ovadine (100 mg/L). The impact of ozone application was evaluated based on hatching success, larval nucleic acid concentration, larval growth, and survival. Overall, results indicated that ozonation of Atlantic Cod eggs at a dose less than 3.0 mg/L for 90 s produced no negative effect on the larvae up to 30 d posthatch. Furthermore, ozonation of Atlantic Salmon and Rainbow Trout eggs generated no negative effect on the larvae, based on monitoring until 85% yolk sac re-absorption (16 d posthatch).
Received May 6, 2014; accepted October 24, 2014 相似文献
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3.
Xi Liang John E. Erickson Wilfred Vermerris Diane L. Rowland Lynn E. Sollenberger Maria L. Silveira 《Journal of Crop Improvement》2017,31(1):39-55
Plant root architecture offers the potential for increasing soil water accessibility, particularly under water-limited conditions. The objectives of this study were to evaluate the root architecture in two genotypes of sorghum (Sorghum bicolor (L.) Moench) differing in root angles and to assess the influence of different deficit irrigation regimes on root architecture. The response of two sorghum genotypes, ‘Early Hegari-Sart’ (EH; steep root angle) and ‘Bk7’ (shallow root angle) to four irrigation treatments was investigated in two replicated outdoor studies using large pots. The results indicated that EH possessed steeper brace and crown root angles, fewer brace roots, greater root biomass, and root length density than Bk7 at deeper soil depths (i.e., 15–30 and 30–45 cm) compared with a shallower depth (i.e., 0–15 cm). Across the soil profile, EH had greater root length density and length of roots of small diameter (<1 mm) than Bk7. Accordingly, EH showed more rapid soil-water capture than Bk7. Different levels of irrigation input greatly affected root architecture. Severe deficit irrigation (25% of full crop transpiration throughout the season) increased the angle and number of crown roots, root biomass, and root length density compared with 75 and 100% of full crop transpiration treatments. Consequently, root system architecture can be effectively manipulated through both genotypic selection and irrigation management to ensure optimal performance under different levels of soil available water. 相似文献
4.
Sharon E. Reed Sylvia Greifenhagen Qing Yu Adam Hoke David J. Burke Lynn K. Carta Zafar A. Handoo Mihail R. Kantor Jennifer Koch 《Forest Pathology》2020,50(3)
A foliar nematode, Litylenchus crenatae ssp. mccannii, is associated with beech leaf disease (BLD) symptoms. Information about the types of tissues parasitized and how nematode populations fluctuate in these tissues over time is needed to improve surveys as well as understand the nematodes role in BLD. During this study, the nematode was detected throughout the known range of BLD by researchers at both Canadian and US institutions using a modified pan method to extract nematodes. Monthly collections of symptomatic and asymptomatic leaves during the growing season (May–October), and leaves and buds between growing seasons (November–March), revealed that nematodes were present in all tissue types. Progressively larger numbers of nematodes were detected in symptomatic leaves from Ohio and Ontario, with the greatest detections at the end of the growing season. Smaller numbers of nematodes were detected in asymptomatic leaves from BLD‐infected trees, typically at the end of the growing season. The nematode was detected overwintering in buds and detached leaves. The discovery of small numbers of nematodes in detached leaves at one location before BLD was detected indicates that nematodes may have been present before disease symptoms were expressed. Other nematodes, Plectus and Aphelenchoides spp., were infrequently detected in small numbers. Our findings support the involvement of the nematode in BLD and indicate that symptoms develop only when certain requirements, such as infection of buds, are met. We also found that the nematode can be reliably detected in buds and leaves using the modified pan extraction method. 相似文献
5.
Allan Fulton Larry Schwankl Kris Lynn Bruce Lampinen John Edstrom Terry Prichard 《Irrigation Science》2011,29(6):497-512
Orchard and vineyard producers conduct preplant site evaluations to help prevent planting permanent tree and vine crops on
lands where the crop will not perform to its highest potential or attain its full life expectancy. Physical soil characteristics
within specific soil profiles and spatially throughout an orchard influence decisions on land preparation, irrigation system
selection, horticultural choices, and nutrient management. Producers depend on soil surveys to help them understand the soil
characteristics of the land and may be interested in technology that provides additional information. Electromagnetic induction
(EM38) and four-probe soil resistance sensors (VERIS) are being used in combination with global positioning systems to map
spatial variability of soils using apparent soil electrical conductivity (ECa). The hypothesis evaluated in this study is
whether rapid, in situ, and relatively low-cost methods of measuring ECa (EM38 and VERIS) can effectively identify and map
physical soil variability in non-saline soils. The supposition is that in non-saline soils, ECa levels will relate well to
soil texture and water-holding capacity and can be used to map physical soil variability. In turn, the information can be
used to guide decisions on preplant tillage, irrigation system design, water and nutritional management, and other horticultural
considerations. Two sites in the Sacramento Valley were mapped each with EM38 and VERIS methods. Site-specific management
zones were identified by each provider on ECa maps for each site, and then soil samples were collected by University of California
researchers to verify these zones. Results showed that on non-saline soils, ECa measured with both EM38 and VERIS correlate
with physical soil properties such as gravel, sand, silt, and clay content but the relationship between conductivity and these
physical soil properties varied from moderately strong to weak. The strength of the correlation may be affected by several
factors including how dominant soil texture is on conductivity relative to other soil properties and on methods of equipment
operation, data analysis and interpretation. Overall, the commercial providers of ECa surveys in this study delivered reasonable
levels of accuracy that were consistent with results reported in previous studies. At one site, an ECa map developed with
VERIS provided more detail on physical soil variability to supplement published soil surveys and aided in the planning and
development of a walnut orchard. At a second site, almond yield appeared to correlate well with distinctly different soil
zones identified with EM38 mapping. 相似文献
6.
Regolin André Luis Oliveira-Santos Luiz Gustavo Ribeiro Milton Cezar Bailey Larissa Lynn 《Landscape Ecology》2021,36(9):2519-2533
Landscape Ecology - An understanding of species-habitat relationships is required to assess the impacts of habitat fragmentation and degradation. To date, habitat modeling in fragmented landscapes... 相似文献
7.
8.
Lynn H. Booth Vanessa J. Heppelthwaite Kathryn O’Halloran 《Journal of Soils and Sediments》2002,2(3):148-154
Objectives and Methods. The sensitivity of two biomarkers, the neutral red retention assay (NRRA) and cytochrome P450 were evaluated in the earthwormAporrectodea caliginosa for their potential to detect exposure to benzo[a]pyrene (BaP). Cytochrome P450 was also evaluated in the earthwormLumbricus rubellus, and measured using the substrate ethoxycoumarin. Optimal assay conditions (pH, and temperature) were determined, followed
by exposure of earthworms to 20 mg/kg BaP (a typical concentration at contaminated sites in New Zealand). Ethoxycoumarin-O-dealkylase
(ECOD) activity was measured after 7, 14, and 21 days exposure. The NRRA was evaluated in earthworms exposed to 0.2, 20, and
100 mg BaP/kg, and biomarker responses were compared with effects on body weight.
Results and Discussion Benzo[a]pyrene failed to induce ECOD activity in either earthworm species, and therefore it is not useful as a biomarker
of BaP exposure and was not evaluated further. In all cases, the NRRA was significantly affected in the absence of any effects
on earthworm body weight, indicating that this assay can detect exposure to BaP at a range of concentrations comparable to
those found at contaminated sites. The NRRA should be linked to reproductive endpoints, then it can be used as an early warning
indicator of adverse effects. Establishing biomarker stability under environmental conditions is an important step in biomarker
development. Therefore, the effects of soil type (sandy soil, silt loam, and a clay soil), moisture content (15–30%), and
temperature (5–20°) on the NRRA were determined. In all cases, there was no effect on the NRRA, indicating that this assay
is very stable under varying environmental conditions.
Conclusion and Outlook In conclusion, cytochrome P450 activity does not appear to be a useful indicator of PAH exposure in eitherA. caliginosa or L.rubellus, and due to the inherently low activity, it is not suitable as a routine biomarker for detecting environmental contamination
by these compounds. In contrast, the NRRA in the earthworm A.caliginosa is a promising indicator of PAH exposure at the concentrations likely to be found in contaminated sites in New Zealand, and
therefore has potential for evaluating these contaminated sites. If the NRRA can be linked to ecologically important life-cycle
endpoints, such as reproduction, then it could be used as an early warning indicator of adverse effects at contaminated sites,
i.e., by measuring biomarker responses in earthworms from a ‘contaminated area’ and comparing these with earthworms from a
matched control area. 相似文献
9.
Turf-banked terrace treads and risers, turf exfoliation and possible relationships with advancing treeline 总被引:4,自引:0,他引:4
Fine-scale geomorphic/pedogenic processes at alpine treeline may facilitate the initial stages of conifer invasion of alpine tundra. Turf-banked terraces and turf exfoliation associated with solifluction may provide both the topographic protection and the seedbed necessary for conifer establishment above treeline. The morphometry, stoniness and surface penetrability of turf-banked terraces were recorded. Whereas differences among sites exist due to topographic constraints, differences in soil penetrability depend on turf exfoliation. Exfoliated turf risers are significantly more penetrable than non-exfoliated solifluction risers and adjacent treads. These penetrable microsites provide favorable conditions for seed germination. The process of turf exfoliation may play a role in conifer advance into tundra during climatic change. 相似文献
10.
Rose NL Sporns P Dodd HM Gasson MJ Mellon FA McMullen LM 《Journal of agricultural and food chemistry》2003,51(10):3174-3178
Nisin variants and fragments were reacted with glutathione, and the products of the reactions were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography/mass spectrometry (LC-MS). Reactions between glutathione and either [Ala5]nisin or [Ala33]nisin resulted in products with two glutathione molecules conjugated to one nisin variant molecule. Only one glutathione molecule was added to [Ala5,Ala33]nisin. Fragmentation of the nisin molecule resulted in nisin 1-12, nisin 1-20, and nisin 1-32 fragments. Each fragment retained two dehydro residues, which subsequently underwent reaction with glutathione. The data indicated that the dehydroalanine residues of nisin are sites of addition for glutathione. Such addition renders the nisin molecule inactive. 相似文献