排序方式: 共有86条查询结果,搜索用时 187 毫秒
1.
Total Replacement of Dietary Fish Oil with a Blend of Vegetable Oils in the Marine Herbivorous Teleost,Siganus canaliculatus 下载免费PDF全文
Shuqi Wang Xuebing Liu Shude Xu Qingyang Wu Cuihong You Óscar Monroig Douglas R. Tocher Yuanyou Li 《Journal of the World Aquaculture Society》2018,49(4):692-702
To investigate the feasibility of total replacement of dietary fish oil (FO) with vegetable oils (VOs) and the optimal dietary polyunsaturated fatty acid (PUFA) level in the marine herbivorous teleost Siganus canaliculatus, six isonitrogenous (32%) and isolipidic (8%) diets were formulated. Control diet used FO as lipid source, whereas diets VO1–VO5 contained various blends of palm, soybean, rapeseed, and linseed oils, in which the dietary PUFA levels were 42.0, 38.2, 33.8, 29.9, and 27.1%, respectively. After S. canaliculatus juveniles were fed with the diets for 9 wk, their growth performance exhibited no significant difference among the dietary groups. The tissue fatty acid (FA) profiles in liver and fillet generally reflected the dietary FA compositions and showed no significant difference among the VO dietary groups. The results suggest that dietary FO can be replaced completely by VO, without affecting their growth performance. Concerning the effects of the dietary FA profile on the survival rate, hepatosomatic index and viscerosomatic index, and PUFA composition in fillets, diets VO1 and VO2 were more favorable compared with diets VO3–VO5. Considering the availability and cost of the VOs, diet VO2 was recommended for practical use in S. canaliculatus. 相似文献
2.
Antioxidant activity and lipid peroxidation in Artemia nauplii enriched with DHA‐rich oil emulsion and the effect of adding an external antioxidant based on hydroxytyrosol 下载免费PDF全文
Elena Viciano Óscar Monroig Carlos Barata Carlos Peña Juan Carlos Navarro 《Aquaculture Research》2017,48(3):1006-1019
Artemia nauplii catabolize polyunsaturated fatty acids (PUFA); in particular, they retroconvert docosahexaenoic acid (DHA, 22:6n‐3), so enrichment is a continuous quest towards increasing PUFA through the use of PUFA‐rich enrichment products. However, optimal conditions during enrichment (aeration, illumination and temperatures around 28°C) tend to accelerate autoxidation of PUFA and the formation of potentially toxic oxidation products. Water‐soluble antioxidants like the polyphenolic compound hydroxytyrosol (3,4‐dihydroxyphenylethanol), a polar molecule found in the water fraction resulting after the milling process of olives, arise as promising compounds to prevent oxidation during Artemia enrichments. We investigated the antioxidant activity and lipid peroxidation in Artemia nauplii during enrichment and the effect of adding an external antioxidant based on hydroxytyrosol during the enrichment with a PUFA‐rich emulsion (M70). For this purpose, the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione‐S‐transferase, glutathione peroxidase), as well as lipid peroxidation, was determined in enriched and unenriched Artemia nauplii. To validate antioxidant activity and lipid peroxidation, in a first experiment, nauplii were enriched with microalgae (Tetraselmis suecica), yeast (Saccharomyces cerevisiae) and M70 emulsion. In a second experiment, enrichment with a commercial emulsion (DC Super Selco), M70, and a combination of M70 and hydroxytyrosol (Hytolive, HYT) added as an external antioxidant were performed. The combination of M70 with HYT produced the best results, in terms of activity of antioxidant enzymes. The analysis of the fatty acids from total lipids showed that the addition of hydroxytyrosol preserved the DHA percentage of enriched nauplii. 相似文献
3.
Wakame, Undaria pinnatifida, is one of the most popular seaweeds used for human consumption in the world. Wakame quality is mainly valued on the basis of its morphological features. Continual inbreeding and directional selection have traditionally been used with economic seaweeds to obtain elite strains with high‐quality forms. In this study, we compared the morphological traits of cultured sporophytes originating from wild and selected strains of U. pinnatifida in Galicia (NW Spain). Seedlings (young sporophytes) of the two strains were cultured at a sheltered site in a coastal bay of Galicia under the same environmental conditions. Sixteen different morphological measurements were taken on cultured sporophytes. We found that the sporophytes of both wild and selected strains were significantly similar in all studied morphological characters. These results suggest that the morphology of cultured strains of U. pinnatifida from Galicia is due to environmental conditions and that specific morphological traits are dependent on the cultivation environment. Consequently, the morphological traits of Galician U. pinnatifida populations are not an important factor in selective breeding for enhanced wakame quality, and hence, for the establishment of a germplasm bank (e.g., gametophyte stocks). 相似文献
4.
Designing pest-suppressive multistrata perennial crop systems: shade-grown coffee in Central America
During most of its cultivation in Central America, coffee (Coffea arabica L.) suffered few serious pest problems. However, over the past three decades, three factors contributed to significantly
increase pest levels and losses: the recent introduction of new pests; more favorable conditions for existing pests, diseases,
and weeds due to lower shade levels; and secondary pest problems caused by pesticide use. The strategy of maximizing coffee
production with pest control dominated by synthetic pesticides has not only increased yields substantially, but also production
costs, pesticide resistance, and both human health and environmental risks. An analysis of the response of the food web in
coffee plantations to varying levels of light and humidity associated with different shade levels provides the basis for identifying
the optimum shade conditions which minimize the entire pest complex and maximize the effects of beneficial microflora and
fauna acting against it. These optimum shade conditions for pest suppression differ with climate, altitude, and soils. The
selection of tree species and associations, density and spatial arrangement, as well as shade management regimes are critical
decisions for shade strata design. Site-specific knowledge of the seasonal food web dynamics permits growers to determine
the appropriate seasonal shade management in order to further suppress pest levels. For example in a low-elevation dry coffee
zone, 35 to 65% shade promotes leaf retention in the dry season and reduces Cercospora coffeicola, weeds, and Planococcus citri; at the same time, it increases the effectiveness of microbial and parasitic organisms without contributing to increased
Hemileia vastatrix levels or reducing yields. In these conditions, shade should be at a maximum early in the dry season and at a minimum by
the middle of the rainy season. Further research is needed on: the effects of individual tree species on the food web; the
role of canopy architecture for coffee vigor, photosynthesis, leaf drying, pest susceptibility, and pruning regimes; and on
simple observation methods and decision criteria for farmer management of tree-coffee-food web interactions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Molecular cloning and functional characterization of a putative Elovl4 gene and its expression in response to dietary fatty acid profiles in orange‐spotted grouper Epinephelus coioides 下载免费PDF全文
6.
Rosa L. OBREGÓN Jose A. SCOLARO Nora R. IBARGÜENGOYTÍA Marlin MEDINA 《Integrative zoology》2021,16(1):53-66
Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature. In particular, niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions. Lizards of the genus Phymaturus are viviparous, mainly herbivorous, and inhabit only rock promontories in the steppe environments of Patagonia and the Andes. Herein, we examine the vulnerability of the southernmost Phymaturus species to global warming: the endemic Phymaturus calcogaster, which lives in a mesic environment in eastern Patagonia. We studied body temperatures in the field (Tb), preferred body temperatures in a thermogradient (Tpref), the operative (Te) and environmental temperatures, and the dependence of running performance on body temperature. P. calcogaster had a mean Tb (27.04°C) and a mean Te (31.15°C) both lower than their preferred temperature (Tpref = 36.61°C) and the optimal temperature for running performance (To = 37.13°C). Lizard activity seems to be restraint during the early afternoon due high environmental temperatures. However, both, the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming (IPCC report in 2018) would not threaten, but indeed enhance locomotor performance in this population. 相似文献
7.
Edgar G. GUTIÉRREZ Isabela VIVAS-TORO Daniela CARMONA-RUÍZ David VILLALOBOS-CHAVES Bernal RODRÍGUEZ-HERRERA Melina Del REAL-MONROY Gloria LEÓN-AVILA Jorge ORTEGA 《Integrative zoology》2021,16(5):646-658
Ectophylla alba is a tent-making bat that roosts in mixed-sex clusters comprising adults and offspring. Our goal was to determine the genetic identity of individuals belonging to different roosting groups. We tested the hypothesis of kin selection as a major force structuring group composition. We used 9 microsatellites designed for E. alba to determine the genetic identity and probability of parentage of individuals. We analyzed parentage and kinship using the software ML-Relate, GenAIEx, and Cervus. The obtained relationship probabilities (0.5) revealed a clear maternal relationship between female adults and offspring with allele compatibility, and at least 5 relationships between male adults and pups. We found a low degree of relatedness within roosting groups. Between roosting groups at different sites, the mean probability of a half-sibling relationship ranged from 0.214 to 0.244 and, for full-sibling relationship, from 0.383 to 0.553. Genetically, adult individuals were poorly related within clusters, and kinship as an evolutionary force could not explain group membership. 相似文献
8.
F. TÓTH N. FRANK T. MARTIN‐JIMÉNEZ S. B. ELLIOTT R. J. GEOR R. C. BOSTON 《Equine veterinary journal》2010,42(2):149-155
Reasons for performing study: Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C‐peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Hypothesis: A human double antibody radioimmunoassay (RIA) detects C‐peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatostatin administered i.v. as a primed continuous rate infusion, followed by 50 nmol human C‐peptide i.v. Insulin and C‐peptide concentrations were measured in horses (n = 6) undergoing an insulin‐modified frequently sampled i.v. glucose tolerance test, and in horses with insulin resistance (n = 10) or normal insulin sensitivity (n = 20). Results: A human RIA was validated for use with equine sera. Endogenous C‐peptide secretion was suppressed by somatostatin and median (range) clearance rate was 0.83 (0.15–1.61) ml/min/kg bwt. Mean ± s.d. C‐peptide‐to‐insulin ratio significantly (P = 0.004) decreased during the glucose tolerance test from 3.60 ± 1.95 prior to infusion to 1.03 ± 0.18 during the first 20 min following dextrose administration. Median C‐peptide and insulin concentrations were 1.5‐ and 9.5‐fold higher, respectively in horses with IR, compared with healthy horses. Conclusions: Endogenous C‐peptide secretion decreases in response to somatostatin and increases after dextrose infusion. Results suggest that relative insulin clearance decreases as pancreatic secretion increases in response to dextrose infusion. Hyperinsulinaemia in insulin resistant horses may be associated with both increased insulin secretion and decreased insulin clearance. Potential relevance: Both C‐peptide and insulin concentrations should be measured to assess pancreatic secretion and insulin clearance in horses. 相似文献
9.
The probability of being employed varies depending on several factors. Many of these are related to personal characteristics such as educational level, age, gender, or number and age of children. Nevertheless, other factors may be relevant, in particular the geographical environment. The purpose of this paper is to analyse the relevance of urban size and the position of each territory (in terms of its distance from large metropolises) for the probability of being employed in the Spanish economy. Following the set of economic regions suggested by Polése, Shearmur and Rubiera (2007 ), we try to explain the spatial patterns of employment distribution. Our results show some relevant differences between these alternative economic areas. We find that municipalities with similar sizes and located at a similar distance from a metropolis but belonging to different Autonomous Communities or provinces share similar employability patterns. 相似文献
10.
The purpose of this paper is to provide empirical evidence on the neighboring effects of Internet adoption as measured by the percentage of firms with their own website in the European regions. This is the first study that explicitly analyzes the role played by spatial effects to explain website adoption for the European case. A set of instruments and techniques commonly used in the spatial econometrics framework is employed to test the hypothesis that proximity matters when explaining Internet adoption by firms. Results show that firms in physically adjacent regions register a similar degree of Internet adoption, confirming the presence in this context of positive spatial dependence. Nevertheless, the spatial effects detected are mainly constrained by national borders. Gross domestic product (GDP) per capita, population density, sectoral composition, and education are positively related to geographic distribution of Internet adoption in the enlarged European Union. In addition, regional disparities in Internet adoption were found to be less important than territorial inequalities in GDP per capita. 相似文献