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1.
To identify ways to improve water quality and shrimp production in closed systems, two parallel experiments (one in tanks and one in ponds) were conducted using Pacific white shrimp, Litopenaeus vannamei, cultures. In both experiments, the effects of inorganic (Nutrilake®) and organic (molasses) fertilization on physicochemical parameters, bacterial concentrations, and shrimp performance under zero water exchange were evaluated. Fertilization with both molasses and Nutrilake enhanced the feed conversion rate, as well as shrimp survival and production. In tanks, the shrimp survival and production rates were highest in the molasses treatment, but this effect was not observed in ponds. In ponds, fertilization with Nutrilake increased nitrogen and phosphorus concentrations more than did the controls and molasses treatments toward the end of the experiment. In tanks, fertilization with molasses reduced ammonia concentrations toward the end of the experiment, but the same effect was not observed in ponds. In ponds, fertilization reduced the proportion of Vibrio spp. bacteria, which most likely reduced the incidence of disease from these potentially pathogenic organisms. In both culture systems, fertilization increased the proportion of Bacillus spp., which most likely enhanced food availability.  相似文献   
2.
A survey was carried out to determine Fusarium species and fumonisin contamination in 55 durum wheat (Triticum turgidum L. var. durum) samples collected during two harvest seasons (2007 and 2008) using HPLC and further LC-MS/MS confirmation. All samples showed Fusarium contamination with infection levels ranging from 8 to 66%, F. proliferatum being the species most frequently isolated during 2007 and the second most frequently isolated one during the 2008 harvest season, respectively. Natural contamination with fumonisins was found in both harvest seasons. In 2007, 97% of the samples showed total fumonisin (FB(1) + FB(2)) levels ranging from 10.5 to 1245.7 ng/g, while very low levels of fumonisins were detected in samples collected during 2008. These results could be explained by differences in the amount of rainfall during both periods evaluated. A selected number (n = 48) of F. proliferatum isolates showed fumonisin production capability on autoclaved rice. This is the first report of the presence of natural fumonisins in durum wheat grains.  相似文献   
3.
This study compares sensory attributes, chemical composition, fatty acid profiles, and the taste of raw and cooked red drum Sciaenops ocellatus fillets, reared in seawater (SW) and in freshwater (FW) aquaculture systems. Significant nutritional differences were found in the raw fillets. The total lipid was higher (5.31%) in FW fish than the SW (2.60%). The ratio n‐3/n‐6 and EPA/DHA was higher in SW than FW fillets. The eicosenoic acid was only present in FW fillets. DHA was dominant in SW specimens, contrary to the arachidonic acid level, which was dominant in FW fillets. The assessors perceived a significant difference in the firmness and colour of raw fillets, but its odour intensity was not affected. Fillets from SW fish have higher acceptability (33.3%) than FW fillets (26.4%). Sensory differences in raw fillet were not correlated with consumer perceptions, as cooked fish was considered to have similar flavour, independent of its origin.  相似文献   
4.
Fusarium wilt of strawberry, caused by Fusarium oxysporum f. sp. fragariae, is a disease of primary concern for strawberry production in many countries. Crop rotation and anaerobic soil disinfestation (ASD) have gained recent interest for their potential to contribute to management of this disease. Both techniques involve incorporation of organic matter into soil, which may be utilized by strains of Fusarium that are competitive saprophytes. We show that F. oxysporum f. sp. fragariae can colonize strawberry, lettuce, raspberry, and broccoli leaf tissues, which are sources of organic matter generated during crop rotation. This pathogen increased in soil population density during ASD treatments that did not become anaerobic, possibly as a result of growth on the organic amendment. However, significant population decreases were observed after ASD treatment when at least 100,000 cumulative reduced mV hours occurred in a 14-day experiment. Post-ASD abundance of F. oxysporum f. sp. fragariae in soil was negatively correlated with cumulative reduced mV hours. The only treatment that consistently caused disinfestation was exposed to a maximum temperature of 22 °C, which indicates there is potential for developing effective ASD treatments in the cool climates where strawberries are grown. Awareness that F. oxysporum f. sp. fragariae can act as a competitive soil saprophyte should be further investigated for its potential to alter disease outcomes where organic amendments are applied.  相似文献   
5.
OBJECTIVE: To review the literature examining associations between environmental factors, energy and fat intakes among adults, and to identify issues for future research. METHODS: Literature searches of studies published between 1980 and 2004 were conducted in major databases (i.e. PubMed, Human Nutrition, Web of Science, PsychInfo, Sociofile). Additional articles were located by citation tracking. RESULTS: Twenty-one articles met the inclusion criteria. No study provided a clear conceptualisation of how environmental factors may influence these dietary intakes. Availability, social, cultural and material aspects of the environment were relatively understudied compared with other factors such as seasonal/day of the week variation and work-related factors. Few studies examined the specific environmental factors implicated in the obesity epidemic, and there was little study replication. All studies were observational and cross-sectional. CONCLUSIONS: It is too premature to conclude whether or not environmental factors play a role in obesogenic and unhealthy dietary intakes. More studies need to examine associations with those environmental factors thought to contribute to obesogenic environments. There needs to be more development in theories that conceptualise the relationship between environmental factors and dietary intakes.  相似文献   
6.
7.
Megaplatypus mutatus (= Platypus mutatus) (Chapuis) is an ambrosia beetle native to South America that attacks live trees, mining deeply into the xylem through large tunnels. This activity weakens the structural integrity of the tree, causing severe stem-breakage and mortality. Attacks are initiated by pioneer males that select a host tree and build short nuptial galleries, to which they attract females using a sexual pheromone. Previously, we showed the potential for the strategy of pheromone-mediated mating disruption of M. mutatus in commercial poplar and hazelnut plantations in South America and Europe using polyethylene reservoir dispensers for pheromones. In the present work we replaced the polymeric reservoir dispensers by monolithic dispensers made by dispersion of the pheromone in natural waxes and the addition of kaolin and we found that: prior to pheromone deployment, the mean number of galleries per tree did not differ significantly between the control and treated plots and the same was observed after the mating disruption treatment for the control plot but not for treated plots, where the mean number of galleries were reduced. These findings confirm that mating disruption is a viable tool for management of M. mutatus in poplar plantations. Using natural wax dispensers has obvious advantages from an environmental point of view.  相似文献   
8.
Red drum (Sciaenops ocellatus) is a euryhaline fish commonly found in the Gulf of Mexico and along the Atlantic coast of North America. Because of high commercial demand and its euryhaline characteristics, aquaculture of this species has diversified from marine to low-salinity aquaculture systems. In recent years, interest in the feasibility of producing red drum in inland freshwater systems has grown and this prompted us to investigate its osmoregulatory capacity after rearing for 8 months in a freshwater aquaculture system. We compared the activities of several genes and enzymes involved in the osmoregulatory process in freshwater-acclimatized (FW) and seawater (SW) red drum. The gene expression profiles were variable: the expression of genes encoding Na+/K+-ATPase (NKA) and the cystic fibrosis transmembrane regulator (CFTR) was slightly higher in SW than FW fish, while phosphoenolpyruvate carboxykinase (PEPCK) and the glucocorticoid receptor messenger RNA (mRNA) levels were higher in FW red drum. The total plasma K concentration was 60.3% lower, and gill NKA activity was 63.5% lower in FW than in SW fish. PEPCK activity was twofold higher in FW than in SW red drum. Similarly, liver glycogen was 60% higher in FW fish. In summary, both gene expression and the enzyme activity data support the phenotypic plasticity of red drum and suggest that the limited capacity for ion homeostasis observed, in particular the low plasma K concentration, was due to the composition of freshwater and does not necessarily reflect a physiological inability to osmoregulate.  相似文献   
9.
Due to their ecologic and economic importance, bradyrhizobia have been extensively studied in recent years. Since 1992, Bradyrhizobium elkanii SEMIA 587 and SEMIA 5019 and Bradyrhizobium japonicum SEMIA 5079 and SEMIA 5080 have been widely used in most Brazilian soybean fields. The objective of this work was to estimate the genetic variability of bradyrhizobial isolates recovered from soils under rhizobial inoculation and different soil managements. Only 25% of the isolates demonstrated high similarities to the original strains, and a strong correlation was obtained between the bradyrhizobial genetic variability and soil management. A high level of genetic diversity was observed both within isolates (H = 5.46) as well as among the different soil practices. Soil under no-tillage presented a higher bradyrhizobia diversity compared with bradyrhizobia isolated from soil under conventional tillage. Serological characterization also indicated that B. elkanii strains SEMIA 587 and SEMIA 5019 were more competitive and presented a higher nodular occupancy capacity than strains belonging to B. japonicum species in Southern Brazilian soils.  相似文献   
10.
Abstract

The effect of long-term freshwater acclimation on the blood and plasma ion composition of Red Drum Sciaenops ocellatus was investigated with the goal of elucidating the necessity of ion remediation. Four replicates (n = 50) of freshwater-acclimated (FW) fish (1.6 ± 0.2 g) were raised in 25-m3 tanks supported by 140,000 L of recirculating water. Four replicates (n = 50) of seawater (SW) fish groups were placed in 40-m3 offshore cages at 32–35 psu. Blood was collected from 100 fish (FW = 578 ± 50 g; SW = 686 ± 45 g) of each group (FW, SW) after 8 months of rearing. During the grow-out phase, the survival of FW and SW fish was 57.5% and 92.2%, respectively. The water ion composition (mainly the Ca2+/K+ [43%] and Ca2+/Mg2+ ratios [1%]) explained 56.6% of the plasmatic ion variability in the fish groups. Freshwater exposure produced significant reductions in osmolality and in several plasma indicators (Na+, Cl?, and Mg2+); the K+ levels from FW fish were the most compromised parameter. The water Ca2+/Na+ ratio had a greater influence (44%) on the plasma chemistry parameters, mainly glucose and creatinine. Freshwater-acclimated fish had a higher percentage of hematocrit, hemoglobin, and red blood cells than SW fish, but the water quality explained only 12.5% of the blood parameter variability between the FW and SW groups. The results support the conclusion that Red Drum tolerates salinity variations and can adopt a relatively stable condition for short periods; however, the data suggest that Red Drum have only a limited ability to withstand a hyposmotic environment for long periods due to their limited ability in maintaining K+ concentrations without external supplementation. Freshwater environments with high Ca2+/Na+, Ca2+/K+, and Ca2+/Mg2+ ratios appear to be a chronic stress factor that should be considered in future experiments.

Received June 11, 2012; accepted March 17, 2013  相似文献   
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