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951.
Acute Toxicity of Ammonia and Nitrite to Painted River Prawn,Macrobrachium carcinus,Larvae 下载免费PDF全文
Rivaldo Siqueira Gomes Jr João Paulo Viana de Lima Ronaldo Olivera Cavalli Eudes de Souza Correia 《Journal of the World Aquaculture Society》2016,47(2):239-247
This study evaluated the toxicity of ammonia and nitrite to different larval stages of Macrobrachium carcinus. Three replicated groups of larvae in the zoea stages II, V, and VIII (hence named Z2, Z5, and Z8, respectively) were exposed separately to five ammonia (5, 10, 20, 40, and 80 mg total ammonia nitrogen [TAN]/L) and six nitrite concentrations (5, 10, 20, 40, 80, and 160 mg NO2‐N/L), plus a control treatment with no addition of ammonia and nitrite, at a salinity of 20 g/L. The ammonia LC50 values at 96 h for Z2, Z5, and Z8 were 8.34, 13.84, and 15.03 mg TAN/L (0.50, 0.71, and 0.92 mg NH3‐N/L), respectively, and the nitrite LC50 values at 96 h for Z2, Z5, and Z8 were 3.28, 9.73, and 34.00 mg NO2‐N/L, respectively. The estimated LC50 values for NO2‐N were lower than those for TAN in most of the stages evaluated. This observation suggests that M. carcinus larvae are more tolerant to ammonia, except at Z8, in which larvae had a higher tolerance to nitrite. Based on the lethal concentrations at 96 h, it may be concluded that the tolerance of M. carcinus to ammonia and nitrite increases with larval development. Safe levels were estimated to be 0.834 mg TAN/L (0.05 mg NH3‐N/L) and 0.328 mg NO2‐N/L; therefore, efforts should be made to maintain lower concentrations of these compounds throughout the larval rearing of M. carcinus. 相似文献
952.
953.
Feeding,body condition and reproductive investment of Astyanax intermedius (Characiformes,Characidae) in relation to rainfall and temperature in a Brazilian Atlantic Forest stream 下载免费PDF全文
Ursulla P. Souza Fabio C. Ferreira Francisco M. de S. Braga Kirk O. Winemiller 《Ecology of Freshwater Fish》2015,24(1):123-132
Life history theory seeks to explain how environmental variation selects for patterns of investment in growth and survival relative to production and survival of offspring. Seasonal variations in rainfall and temperature provide environmental cues for spawning by many tropical freshwater fishes. To investigate environment–life history associations, we conducted a one‐year study of Astyanax intermedius in an Atlantic Forest stream of southeastern Brazil. Our analysis focused on temporal variation in feeding, body condition and reproduction in relation to rainfall and water temperature. For mature females, food intake was not significantly correlated with rainfall or temperature; however, body condition was negatively correlated with rainfall and water temperature. Female reproductive effort was positively correlated with water temperature, but did not vary with rainfall. For males and juveniles, there was no significant relationship between food intake or body condition and either environmental variable. Testis weight was negatively correlated with rainfall, but was not significantly correlated with water temperature. We detected a negative correlation between gonad mass with body condition and food intake for females but not for males. Our results differed from other studies in tropical and subtropical areas where rainfall has been shown to be positively correlated with fish reproductive effort. Our results indicate that reproductive effort of males is relatively constant throughout the year, whereas for females, it increases with increasing water temperature. This increase in reproductive investment in concert with an increasing temperature and metabolic rate may incur a trade‐off with somatic growth and survival for this small stream fish. 相似文献
954.
Luciana Lasry Benchimol Tatiana de Campos Sérgio Augusto Morais Carbonell Carlos Augusto Colombo Alisson Fernando Chioratto Eduardo Fernandes Formighieri Lígia Regina Lima Gouvêa Anete Pereira de Souza 《Genetic Resources and Crop Evolution》2007,54(8):1861-1762
A common bean genomic library was constructed using the ‘IAC-UNA’ variety enriched for (CT) and (GT) for microsatellite motifs.
From 1,209 sequenced clones, 714 showed microsatellites distributed over 471 simple and 243 compound motifs. GA/CT and GT/CA
were the most frequent motifs found among these sequences. A total of 123 microsatellites has been characterized. Out of these,
87 were polymorphic (73.7%), 33 monomorphic (26.8%), and 3 (2.4%) did not amplify at all. In a sample of 20 common bean materials
selected from the Agronomic Institute Germplasm Bank, the number of alleles per locus varied 2–9, with an average of 2.82.
The polymorphic information content (PIC) of each marker varied from 0.05 to 0.83, with a 0.45 average value. Cluster and
principal coordinate analysis of the microsatellite data were consistent with the original assignment of the germplasm accessions
into the Andean and Mesoamerican gene pools of common bean. Low polymorphism levels detected could be associated with the
domestication process. These microsatellites could be a valuable resource for the bean community because of their use as new
markers for genetic studies.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.
An erratum to this article can be found at 相似文献
955.
Albuquerque MR Silveira ER De A Uchôa DE Lemos TL Souza EB Santiago GM Pessoa OD 《Journal of agricultural and food chemistry》2004,52(22):6708-6711
The volatile composition of the essential oils from leaves and roots of Eupatorium betonicaeforme (D.C.) Baker was analyzed by GC-MS. A total of 12 compounds were identified. beta-Caryophyllene (12.4-41.7%), alpha-humulene (11.7-14.6%), gamma-muurolene (10.4-19.0%), bicyclogermacrene (15.0-17.5%), 2,2-dimethyl-6-vinylchroman-4-one (10.3-25.5%), and 2-senecioyl-4-vinylphenol (8.5-41.0%) were the most prominent constituents. The former two compounds were isolated and characterized by spectroscopic data. The essential oils and the isolated compounds were tested against Aedes aegypti larvae survival. The results obtained show that the essential oil from roots and 2,2-dimethyl-6-vinylchroman-4-one (10.3-25.5%) could be considered as natural larvicidal agents. 相似文献
956.
957.
P.M. Chalk R. de F. Souza S. Urquiaga B.J.R. Alves R.M. Boddey 《Soil biology & biochemistry》2006,38(9):2944-2951
Legumes may respond to non-rhizobial inoculants such as arbuscular mycorrhizal (AM) fungi either through an effect on plant growth or, in addition, through an effect on the function of the legume-Rhizobium symbiosis. We have examined the literature where the application of 15N isotope dilution methodology permits the effect of indigenous AM and AM inoculants to be quantitatively separated into plant-growth-mediated and biological N2 fixation (BNF)-mediated components. These studies clearly demonstrate the beneficial effects that both indigenous and inoculated AM have on legume growth, N uptake and the proportional dependence of the legume on atmospheric N2. While the published data allow an assessment of various biological, edaphic and environmental factors that affect the response of various legumes to AM inoculation, they also highlight the paucity of quantitative field data and the lack of understanding of the interaction of legume genotype with AM species with respect to legume symbiotic performance. 相似文献
958.
H. A. Souza D. E. Rozane D. A. Amorim V. C. Modesto W. Natale 《Journal of plant nutrition》2016,39(2):235-243
Studies of the effect of organic fertilization of perennial crops are scarce due to the time necessary for the plants to present the first results. The objective of this study was to assess the leaf nitrogen (N) content, the direct and indirect measures of chlorophyll content, fruit yield and their correlations in an orchard of adult guava trees of the Paluma cultivar, through five consecutive harvests, in function of application of a byproduct of guava processing. The following doses of the byproduct were applied: 0, 9, 18, 27 and 36 t ha?1. The material was applied on the surface, without incorporation, once a year between 2006 and 2010. The byproduct doses influenced the nitrogen concentrations, SPAD index, chlorophyll b level and fruit production. 相似文献
959.
María Sol Souza Beatriz Estela Modenutti Esteban Gabriel Balseiro 《Water, air, and soil pollution》2007,183(1-4):49-57
In freshwater environments direct biological effect of ultraviolet radiation (UVR) result from absorption of specific wavelengths by macromolecules and alteration of biochemical processes. Indirect effects are related to UVR interaction with water and dissolved organic carbon to form chemically reactive species (ROS: reactive oxygen species). Zooplankton photoprotection includes mycosporine-like amino acids, pigments, production of quenching agents and antioxidant enzymes. The relative importance of each mechanism would depend on the organisms. In this study, we determined the antioxidant enzyme activities Catalase (CAT) and Glutathione-S-transferase (GST) in the copepod Boeckella gracilipes and the cladoceran Ceriodaphnia dubia in three Andean lakes of the North-Patagonia region. There were differences in antioxidant enzymes expression between copepods and cladocerans. CAT was significantly higher in C. dubia than in B. gracilipes whereas GST was similar in both species. The comparison of B. gracilipes enzyme activity in the three lakes showed also differences in GST but not in CAT. DOC decreases the exposure by absorption of UVR but simultaneously acts as photosensitizer producing ROS and their successive toxic products in the surface waters. We discuss that comparisons among lakes of different DOC should be considered carefully because lake physico-chemicals parameters, as well as food web structure, will difficult any predictions on the net effect of DOC. 相似文献
960.
Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area,Jordan,where intensive greenhouse production system(IGPS) has been practiced since 1998,to study the impact of IGPS on soil quality as measured by the chemical and biological properties to develop a sustainable production system.The study showed that IGPS led to higher electrical conductivity in top- and subsoils compared to an uncultivated soil(control).Quality and amount of irrigation water,lack of efficient drainage,and quantity and types of applied fertilizers were major factors resulting in salt buildup.IGPS resulted in lower total N(TN) and NO3-N in the soil compared to the control.The lower TN was due to crop uptake,microbial immobilization,volatilization,and irregular application of composted animal manure or poultry manure.In contrast,higher residual Olsen-P content was detected in both soil layers of greenhouses than in the control.Residual P was classified as very high in the topsoil layers and sufficient to high in the subsoil layers.Residual available K in the soils of greenhouses was relatively lower than that in the control and it was,however,classified as high to very high.A large increase of Cl and a considerable decrease in the bacterial count were observed in both soil layers of IGPS compared to the control treatment.Economically sustainable soil management practices need to be adopted by farmers to achieve a sustainable and profitable production.This can be accomplished through education,targeted towards the farming community in the central Jordan Valley. 相似文献