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991.
High levels of protein in fish feeds result in higher costs and nitrogen waste. Therefore, studies focused on protein substitution by alternative energy sources are necessary. Here we examine whether the protein:carbohydrate ratio in extruded diets affects protein-turnover parameters and the main tissue components in brown trout. Juvenile fish were adapted to two extruded diets: one higher in protein and lower in carbohydrate, C: 45/28 and the other higher in carbohydrate and lower in protein, HC: 37/40. Gross energy was 19 MJ kg−1 DM in both diets. Protein and lipid digestibility were high and similar in both groups (≈90%), whereas total and carbohydrate digestibility and digestible energy were lower in the HC-fed group than in the C-fed group. Consequently, when fish were adapted to the diets, plasma levels of glucose and insulin differed between diets. HC-group presented higher plasma glucose levels and lower plasma insulin levels than C-group. Protein synthesis rates in white muscle, liver and whole body did not differ significantly between diets. In contrast, protein accretion rate of white muscle and whole body were significantly lower in the HC group, indicating an increase of protein degradation in these tissues and a decrease of synthesis retention efficiency. In spite of the daily protein intake of HC group was lower than C-group, the anabolic stimulation efficiency was increased by 34% in HC group. Protein and lipid contents in white muscle and liver were stable throughout the experiment. No hepatomegalia or increased fat deposition was observed in fish fed HC. Differences in specific growth rates (C: 0.88%; HC: 0.77%) were associated more with the lower protein consumption rate and the lower level of digestible energy in fish fed HC than with the higher dietary carbohydrate content of the diet. 相似文献
992.
L. RODÁK Z. POSPÍIL J. TOMÁNEK T. VESELÝ T. OBR L. VALÍEK 《Journal of fish diseases》1993,16(2):101-111
Abstract. An enzyme-linked immunosorbent assay (ELISA) for the demonstration of the virus of spring viraemia of carp (SVCV) in liver, kidney and spleen homogenates, and in infected cell cultures is described. The sensitivity of the method is 102·8 –103·5 TCID50 0·lml−1 of the examined fluid. The specificity has been confirmed by the ELISA inhibition test and by results of virological examinations. Contamination with bacteria or fungi of samples taken from dead fish had no effect on the results of ELISA. Specific anti-SVCV sera were used successfully for the production of conjugates for the direct immunoperoxidase and immunofluorescence detection of SVCV in infected cell cultures. 相似文献
993.
C.?A.?Alvarez-González M.?Cervantes-Trujano D.?Tovar-RamírezEmail author D.?E.?Conklin H.?Nolasco E.?Gisbert R.?Piedrahita 《Fish physiology and biochemistry》2005,31(1):83-93
California halibut Paralichthys californicus is an important commercial species with high aquaculture potential in Baja California Sur, México. To optimize the feeding
process using live prey and/or inert diets, we evaluated alkaline proteases, pepsin, trypsin, chymotrypsin, leucine aminopeptidase,
lipase, α-amylase, and acid and alkaline phosphatase activities on starved larvae and larvae fed live prey. Highest activities
were observed for alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, and alkaline phosphatase in feeding larvae
than starved larvae on day 4 after hatching. At day 5, a sizeable increase in all enzymatic activities was detected in feeding
larvae. Alkaline protease, trypsin, chymotrypsin, and alkaline phosphatase decreases progressively from day 5 until day 18.
At day 18, a slight pepsin activity was observed. This was considered an indicator of the start of digestive system maturation.
We concluded that total enzymatic equipment for this species is complete between day 18 and 30 after hatching. Based on this
evidence, early weaning from live prey to inert feed would be possible at this time. 相似文献
994.
Kátia Paula Aleixo Letícia Biral de Faria Milton Groppo Maurício Meirelles do Nascimento Castro Cláudia Inês da Silva 《Urban Forestry & Urban Greening》2014,13(4):689-696
Cities provide resources for the animals that live in them or their surroundings. There has been an increase in the number of ecological studies in urban areas, including interactions between plants and bees. Bees are pollinators that provide a vital ecosystem service to crops and wild plants. We assessed plant community structure in the campus of Universidade de São Paulo in Ribeirão Preto, Brazil, included in the neotropical Atlantic Forest biome, focusing on floristic composition, pollination syndromes, flowering phenology, and spatiotemporal distribution of floral resources for bees. Currently, the city is surrounded by sugar cane plantations. Once a month, from April 2011 to March 2012, we sampled plant species and individuals in bloom in an area with 500 m radius from the bee-rearing facilities of Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), totaling 78 hectares. We sampled 289 plant species of 73 families; Leguminosae was the richest family. Plants pollinated by bees predominated (67%), followed by plants pollinated by hummingbirds (18%). Melittophilous species flowered throughout the year and, hence, food availability for bees was continuous. The flowering of plant individuals that provided pollen, nectar, and floral oil was seasonal in all vegetation (except for nectar in shrubs), with peaks in resource availability in the transition from the dry to the rainy season, and also in the rainy season. Our results show that the campus is able to maintain bee populations amid a monoculture matrix, acting as a refuge. In addition, it provides a list of several attractive native plants to different pollinator groups, coupled with a phenogram, that can be used in the design and planning of urban areas. 相似文献
995.
The UV curing reaction of the difference between allyl abietate(AA) and allyl isopimarate(AI) was studied. The conversion rate of the vinyl double bond was characterized and detected by FT-IR analysis. Results showed that conversion of double bonds are firstly increased then decreased with the increases of the dosage of initiators. Conversion of double bonds firstly increased and then leveling off with the increases of the illumination time, and AA is higher before the 200 s. AA is higher then AI under the same illumination intensity. Surface drying time of AA is shorter than AI, and relative curing speed become faster at the same conditions. Under the conditions of 2-hydroxy-2-methylpropiophenone(Darocure-1173)as photo initiator and dosage 6%, illumination time 200 s, illumination distance 4.5 cm and illumination intensity 100%, number average molecular weight of cure products of AA and AI are 4 176 and 9 407 with polymerisation degrees of 12 and 28, respectively. The obtained UV cured coating all have smooth and transparent appearance. It represented some superior properties in flexibility, mechanical impact strength, adhesive power, hardness, acid resistance, alkali resistance, salt resistance, water resistance, etc.. The hardness of AA and AI cured products are H and HB, respectively. 相似文献
996.
997.
Characterization of acetylcholinesterase and its molecular forms in organs of five freshwater teleosts 总被引:1,自引:0,他引:1
J. Ferenczy T. Szegletes T. Bálint M. Ábrahám J. Nemcsók 《Fish physiology and biochemistry》1997,16(6):515-529
The activity and molecular forms of acetylcholinesterase (AChE, EC 3.1.1.7) were characterized in the brain, heart, white skeletal muscle and liver of the Siberian sturgeon (Acipenser baeri), European eel (Anguilla anguilla), wels (Silurus glanis), common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix), belonging in four families. The brain had the highest (between 183.2±10.6 and 1361.2±189.7 mU mg-1 protein and between 4.7±0.4 and 23.5±2.7 U g-1 wet tissue) and the liver the lowest (between 25.3±1.9 and 126.5±22.7 mU mg-1 protein and between 1.0±0.1 and 4.5±0.5 U g-1 wet tissue) activity in all these fish, with the exception of the wels, where the heart contained the smallest amount of AChE (26.2±7.5 mU mg-1 protein and 1.2±0.3 U g-1 wet tissue). The highest tissue AChE activity was found in the carp and lowest in the sturgeon. The solubility properties and molecular forms of AChE in the four tissues were studied by extraction in high-salt medium (1.0 M NaCl) with and without the detergent Triton X-100 (0.5%, v/v). The proportions of detergent-soluble (DS) and salt-soluble (SS) forms of AChE varied considerably from one species to another, but a general tendency could be observed: the proportion of DS AChE was generally higher in the brain (between 70.4±4.1 and 82.5±1.2%) and lower in the heart (between 12.0±2.0 and 51.3±2.3%) and skeletal muscle (between 16.0±2.0 and 64.4±0.7%). Velocity sedimentation centrifugation revealed that most tissues contained the G4 or A4 form. Three tissues (brain, heart, and liver) of the Siberian sturgeon contained a relatively high proportion of the G1 form (between 24.3±2.4 and 28.6±4.9%), while the skeletal muscle of the wels contained only the most complex type of AChE, i.e., A12. Amongst the tissues studied, the brain and liver mostly contained amphiphilic globular forms of the G4 type, while the heart and skeletal muscle were rich in asymmetric forms (A4 and A12). It was concluded that the differences revealed in the activities of AChE and in the distribution of its molecular forms may be connected with the variation in behavioral habits (feeding and swimming patterns), and the developmental stage of the nervous system. 相似文献
998.
- Amphibian populations worldwide are in decline. Proactive conservation techniques such as translocations into created and restored wetlands have gained popularity in recent years but may fail owing to high predation and low environmental adaptability.
- The Mexican axolotl (Ambystoma mexicanum), affected by rapid urbanization, is now possibly extinct in the wild despite millions living in captivity throughout the world.
- The aim of this study was to explore whether ponds from an artificial wetland can function as temporary shelters for a viable population of axolotls that could be re-introduced into their native ecosystem in Xochimilco once it is restored.
- Egg-laying and hatching of 11 unique axolotl pairs placed into reproductive enclosures and larval survival to 7 weeks and up to 12 months were examined. Physicochemical and biological parameters were estimated and compared among ponds.
- The results from this study are encouraging as they suggest that two ponds have adequate conditions for axolotls to reproduce and for larvae and juveniles to survive.
999.
Amaiur Esnaola Vanessa Mata Aitor Arrizabalaga-Escudero Jorge González-Esteban Aitor Larrañaga Hugo Rebelo Arturo Elosegi Joxerra Aihartza 《水产资源保护:海洋与淡水生态系统》2021,31(7):1859-1872
- The Pyrenean desman (Galemys pyrenaicus) is an endangered stream-dwelling insectivore endemic to the Iberian Peninsula and the north of the Pyrenees. It favours riffles over slow habitats such as runs or pools, yet it is still unclear whether habitat preference is based on prey availability or on other factors, such as mechanical constraints on its hunting habits.
- Desman diet and prey selection were analysed along the pristine Elama Stream and the slightly modified Leitzaran Stream in the Basque Country, Spain.
- In each stream the prey consumed were identified by metabarcoding 94 desman faeces, and prey availability characterized from 10 Surber samples taken in each habitat type (riffles, runs and pools). Invertebrates were sorted and identified, the biomass of each taxon was calculated, and their DNA was also extracted, amplified using PCR, and sequenced to build a reference database.
- Prey availability and diet varied between streams. Desmans positively selected shredders and invertebrates that live on the substrate, and selected against taxa that live in fine sediment, taxa with hard shells or those that are highly mobile. The diet of desmans was more selective in the Elama, the stream with better ecological status. Food availability did not differ among habitats, and therefore does not explain the preference of desmans for riffles; rather, mechanical constraints to deal with buoyancy and physical habitat heterogeneity were hypothesized to be the reason behind the habitat preference.
- The results suggest that promoting the formation of riffles in streams can improve the situation of some desman populations living in degraded habitats.
1000.
Valeria Hidalgo-Ruz Guillermo Luna-Jorquera Marcus Eriksen Hanna Frick Diego Miranda-Urbina Matias Portflitt-Toro Marcelo M. Rivadeneira Christopher J.R. Robertson R. Paul Scofield Juan Serratosa Cristián G. Suazo Martin Thiel 《水产资源保护:海洋与淡水生态系统》2021,31(2):389-407
- While floating near the sea surface plastic debris interacts with a number of external factors, including many different organisms. Seabirds have the most extensive documented history of interactions with plastics, through ingestion, entanglement, and nest construction.
- In the present study, eight seabird species from the South Pacific Ocean were used as a proxy to determine potential patterns of removal of marine plastic debris, and three hypotheses were tested in relation to their feeding habits and nesting areas.
- Plastics from abiotic compartments (Chilean continental coast, South Pacific Gyre, and Rapa Nui beaches) and biotic compartments (surface-feeding seabirds, diving seabirds, and nesting areas) were compared, according to their type, colour, shape, and density.
- Continental beaches had a relatively wide range of colours and shapes, with many non-buoyant plastics. Samples from the South Pacific Gyre (SPG) and Rapa Nui (Easter Island) beaches comprised mainly hard, rounded, buoyant, and white/grey plastics.
- These results indicate that the composition of floating plastics from terrestrial sources changes during transport with oceanic currents, reducing the proportion of prey-like plastics present in the subtropical gyres.
- The stomach contents of surface-feeding and diving seabirds were dominated by hard, white/grey, and round plastic items, similar to plastics from the SPG, suggesting non-selective (accidental or secondary) ingestion.
- Nesting areas had a more variable composition of brightly coloured plastics, suggesting a pattern of selective removal of plastics by seabirds, probably from oceanic sources.
- The present study reveals extensive interactions of seabirds with plastics on a broader scale, which is highly relevant given that the impacts of plastics on seabirds are increasing worldwide, compromising their efficient conservation.