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1.
Nutrient digestibility studies in Heteropneustes fossilis (Bloch), Clarias batrachus (Linnaeus) and C. gariepinus (Burchell) 总被引:1,自引:0,他引:1
The apparent digestibility coefficient (ADC %) for protein in catfishes, Clarias batrachus (Linnaeus) (16–18 cm; 45–50 g), C. gariepinus (Burchell) (21–22 cm; 60–65 g) and Heteropneustes fossilis (Bloch) (10–12 cm; 10–15 g) was estimated for nine feedstuffs of plant and animal origin. Fat digestibility was tested for C. batrachus and C. gariepinus, wherein the influence of feeding frequency on protein digestibility was also examined. The digestibility trials were conducted with triplicate groups of 25 fish each in 70‐L polyvinyl indoor flow‐through (1–1.5 L min?1) circular tanks (water volume=55 L). Fish were fed to satiation daily, at 08:00 and 18:00 hours, and faecal matter was collected through slow siphoning. For studying the effect of feeding frequency, fish were fed the experimental diets at 08:00, 11:00, 14:00 and 17:00 hours. The protein digestibility of the feedstuffs varied significantly within each test species. However, the protein digestibility values for most of the ingredients tested were comparable between the three catfish species. The most efficient utilization of protein in these fishes was noted for soybean meal followed by lab‐prepared fishmeal. The lowest protein digestibility was recorded for rice bran. Similarly, the utilization of fat from the feedstuffs was also significantly different within each of the two species, C. batrachus and C. gariepinus. Fat digestibility of feed ingredients was similar between the two species. With respect to the fat, soybean meal, lab‐prepared fishmeal, full‐fat soybean meal and dried fish were more efficiently utilized, while the lowest fat digestibility was obtained for rice bran. A marked decline in protein utilization was observed in the two species where the feeding frequency was increased from two to four times a day. 相似文献
2.
Antoine LF Gady Freddy WK Hermans Marion HBJ Van de Wal Eibertus N van Loo Richard GF Visser Christian WB Bachem 《Plant methods》2009,5(1):13-14
Background
The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal. 相似文献3.
Mohammad I. Khalil Muhammad S. Rahman Urs Schmidhalter Hans‐Werner Olfs 《植物养料与土壤学杂志》2007,170(2):210-218
A 90‐day laboratory incubation study was carried out using six contrasting subtropical soils (calcareous, peat, saline, noncalcareous, terrace, and acid sulfate) from Bangladesh. A control treatment without nitrogen (N) application was compared with treatments where urea, ammonium sulfate (AS), and ammonium nitrate (AN) were applied at a rate of 100 mg N (kg soil)–1. To study the effect of N fertilizers on soil carbon (C) turnover, the CO2‐C flux was determined at nine sampling dates during the incubation, and the total loss of soil carbon (TC) was calculated. Nitrogen turnover was characterized by measuring net nitrogen mineralization (NNM) and net nitrification (NN). Simple and stepwise multiple regressions were calculated between CO2‐C flux, TC, NNM, and NN on the one hand and selected soil properties (organic C, total N, C : N ratio, CEC, pH, clay and sand content) on the other hand. In general, CO2‐C fluxes were clearly higher during the first 2 weeks of the incubation compared to the later phases. Soils with high pH and/or indigenous C displayed the highest CO2‐C flux. However, soils having low C levels (i.e., calcareous and terrace soils) displayed a large relative TC loss (up to 22.3%) and the added N–induced TC loss from these soils reached a maximum of 10.6%. Loss of TC differed depending on the N treatments (urea > AS > AN >> control). Significantly higher NNM was found in the acidic soils (terrace and acid sulfate). On average, NNM after urea application was higher than for AS and AN (80.3 vs. 71.9 and 70.9 N (kg soil)–1, respectively). However, specific interactions between N‐fertilizer form and soil type have to be taken into consideration. High pH soils displayed larger NN (75.9–98.1 mg N (kg soil)–1) than low pH soils. Averaged over the six soils, NN after application of urea and AS (83.3 and 82.2 mg N (kg soil)–1, respectively) was significantly higher than after application of AN (60.6 mg N (kg soil)–1). Significant relationships were found between total CO2 flux and certain soil properties (organic C, total N, CEC, clay and sand content). The most important soil property for NNM as well as NN was soil pH, showing a correlation coefficient of –0.33** and 0.45***, respectively. The results indicate that application of urea to acidic soils and AS to high‐pH soils could be an effective measure to improve the availability of added N for crop uptake. 相似文献
4.
Mai H. ElNaggar Ghada M. Abdelwahab Omnia Kutkat Mohamed GabAllah Mohamed A. Ali Mohamed E. A. El-Metwally Ahmed M. Sayed Usama Ramadan Abdelmohsen Ashraf T. Khalil 《Marine drugs》2022,20(3)
Several natural products recovered from a marine-derived Aspergillus niger were tested for their inhibitory activity against SARS CoV-2 in vitro. Aurasperone A (3) was found to inhibit SARS CoV-2 efficiently (IC50 = 12.25 µM) with comparable activity with the positive control remdesivir (IC50 = 10.11 µM). Aurasperone A exerted minimal cytotoxicity on Vero E6 cells (CC50 = 32.36 mM, SI = 2641.5) and it was found to be much safer than remdesivir (CC50 = 415.22 µM, SI = 41.07). To putatively highlight its molecular target, aurasperone A was subjected to molecular docking against several key-viral protein targets followed by a series of molecular dynamics-based in silico experiments that suggested Mpro to be its primary viral protein target. More potent anti-SARS CoV-2 Mpro inhibitors can be developed according to our findings presented in the present investigation. 相似文献
5.
AEF Silva P Rodriguez LF Cavalcante BA Rodrigues JL Rodrigues 《Reproduction in domestic animals》2009,44(S2):259-262
High in vitro oxygen (O2 ) tensions are associated with enhanced levels of reactive oxygen species and cumulus oocyte complex (COC) apoptosis. The objective of this study was to determine the influence of O2 tension on cumulus cell (CC) viability from canine oocytes. Cumulus oocyte complexes were distributed into three groups (CG, T20 and T5) and two O2 tension levels (20% and 5%). The control group (CG) was matured in vitro in a humidified atmosphere with 5% CO2 in air in TCM199 with 26.19 m m sodium bicarbonate, 10% (v/v) foetal calf serum (FCS), 0.10 m m gentamicin, 0.20 m m pyruvic acid, 20 μg/ml oestradiol, 0.5 μg/ml follicle-stimulating hormone, 0.03 IU/ml human chorionic gonadotropin, and 1.0 μg/ml human somatotropin. Groups T20 and T5 were matured under 20% or 5% O2 tensions respectively in a high-glucose medium, without FCS. T20 and T5 were as CG, and supplemented with 0.1% Polyvinyl Alcohol, and 5.5 m m glucose. After 48 h of IVM, CCs from COCs were stained with propidium iodide (1.50 m m ). The results showed that viability of CCs (cytoplasmic features and nuclear morphological integrity) was different for the three groups. Rates of apoptosis were at 57.9% (521/900) for CG, 54.4% (490/900) for T20 and 38.9% (350/900) for T5 (p < 0.001). Predominant features in apoptotic cells (n = 1361) were DNA nuclear fragments (94.0%). It was concluded that CCs of canine COCs cultured in high-glucose medium showed significantly less apoptosis than those cultured in medium with FCS. Low O2 tension was efficient in reducing apoptosis in canine CCs. 相似文献
6.
Repellency and toxicity of aromatic plant extracts against the mosquito Culex pipiens molestus (Diptera: Culicidae) 总被引:2,自引:0,他引:2
The insecticidal activities of essential oil extracts from leaves, flowers and roots of aromatic plants against fourth-instar larvae of the mosquito Culex pipiens molestus Forskal were determined. Extracts of Foeniculum vulgare Mill were the most toxic, followed by those of Ferula hermonis Boiss, Citrus sinensis Osbeck, Pinus pinea L, Laurus nobilis L and Eucalyptus spp with LC50 values of 24.5, 44.0, 60.0, 75.0, 117.0 and 120.0 mg litre(-1), respectively. Combination tests between the LC50 and the maximum sub-lethal concentration (MSLC) were determined. Over 20 major components were identified in extracts from each plant species tested. Five essential oils and nine pure components were studied for their repellency against mosquito bites. Terpineol and 1,8-cineole were the most effective against Culex pipiens molestus bites offering complete protection for 1.6 and 2 h, respectively. 相似文献
7.
Contribution of technic materials to the mobile fraction of metals in urban soils in Marrakech (Morocco) 总被引:3,自引:2,他引:3
Hicham El Khalil Christophe Schwartz Ouafae Elhamiani Jochen Kubiniok Jean Louis Morel Ali Boularbah 《Journal of Soils and Sediments》2008,8(1):17-22
Background, Aim and Scope In urban areas, soils are often dramatically altered by anthropogenic activity and these modifications distinguish these soils
(Anthrosols, Technosols) from those in natural systems. In urban environments, they receive considerable pollution from industry,
traffic and refuse. Since contaminated soil particles can be easily inhaled or ingested, there is a potential transfer of
toxic pollutants to humans. Risk assessment is essentially based on the determination of the total or mobile contents of pollutants
in soils using chemical extractions. This approach could be improved by taking into consideration the bioavailable fractions
of these toxic elements as measured by biotests. The coarse soil fraction usually neglected in analyses can nevertheless have
an effect on the concentration of metals in the soil solution. This coarse fraction is made up of the natural materials and
of technic materials constituting anthropogenic soils (plastic, paper, fabric, wood, bones, metallic elements and building
materials). These materials have variable capacities to release or adsorb trace elements. Samples representative of different
technic fraction components of Marrakech urban soils permit one to quantify their contribution to the enrichment of the soluble
metal concentrations. Works are carried out to achieve partial extractions of metals from the three fractions (less than 2
mm, coarse natural and coarse technic) of selected urban soils in order to determine their contribution to the metal contamination
of soils.
Materials and Methods Selected soils were collected from 9 sites according to a gradient of increasing anthropogenic influence from suburban to
urban zones. Soils were air-dried, homogenized, and sieved (2 mm). The coarse fraction was sorted to separate the different
technic materials and natural materials. Water extractions were run, on the natural, coarse fraction, on the complete technic
fraction of the 9 soils and on average samples made of technic materials sorted out of 58 topsoils sampled from different
sites in the city of Marrakech.
Results Results show that the percentage of the technic fraction increases while approaching the historic city center. It represented
about 14% in the most anthropogenically disturbed soils. Along this gradient, soils changed progressively from Anthrosols
to Technosols according to the WRB classification of urban and industrial soils. Analyses of metal contents showed that the
fine fraction (<2 mm) mainly contributed to the metallic contamination of the water soluble fraction. The natural coarse fraction
had the highest contribution to the copper release and was responsible for the release of all water-extractable copper in
some soils. Concerning the technic fraction, it has a significant contribution essentially in the most anthropogenically disturbed
soils as characterized by an elevated percentage of anthropogenic elements. The water extractable metal contents of average
samples of these anthropogenic elements shows that elevated metal concentrations were released by bones, wood, plastic and
fabric/paper.
Discussion This study concerns soils in urban areas, which are strongly impacted by human activities. Part of the soils can be classified
as Anthrosols, profoundly impacted through the addition of organic materials from household wastes, irrigation, or cultivation.
Other soils strongly impacted by human activities are Technosols dominated or strongly influenced by man-made materials. Technosols
appear mostly in urban and industrial areas and are more likely to be contaminated than Anthrosols. The composition and heterogeneity
of urban soils lead to modifications of the mobility and availability of pollutants depending on successive land-uses and
on the composition of technic materials. The fine fraction offers a high transferring surface capacity, leading to a high
mobilization of metals. The technic fraction contributes significantly to the metal release in the Technosols. This property
can be explained by a reversible adsorption of metals on the organic matter.
Conclusions Results confirm that anthropogenic activity causes a wide spatial diversity of soil quality in the urban and suburban area.
It introduces large amounts of technic materials in soils that could have an impact on the metal availability. It therefore
acts on the metal bioavailability in the urban Technosols.
Recommendations and Perspectives These results show that it is necessary, in addition to the characterization of the fine particles, to take into account the
contribution of the coarse fraction of the Technosols in the evaluation of risks of transfer of metals to the food chain. 相似文献
8.
Mohammad Afzal Khan Ahmad Khalil Jafri & Narendra Kumar Chadha 《Aquaculture Research》2004,35(13):1277-1285
Growth, reproductive performance, muscle and egg composition were investigated in grass carp, Ctenopharyngodon idella (Valenciennnes), fed hydrilla or formulated diets with varying protein levels. Five experimental diets, with varying levels (20%, 25%, 30%, 35% and 40%) of crude protein (CP), were used. One of the fish groups was fed hydrilla. Fish (44.1±0.3 cm; 913±9 g) were stocked (20 tank?1) in outdoor concrete tanks (20 × 10 × 1.5 m) in duplicate, and fed to satiation, twice daily, at 09:00 and 17:00 hours for the experimental duration of 360 days. High (P<0.05) weight gain was recorded in fish fed 30% and 35% CP diets. However, values for gonadosomatic index (GSI), egg diameter, relative fecundity (eggs kg?1 body weight), fertilizability and hatchability (%) were comparable (P>0.05) in fish at ≥25% of dietary protein intake. Hydrilla‐fed fish exhibited lower (P<0.05) values for the measured parameters. Crude protein content in muscle increased with dietary protein level. Highest (P<0.05) muscle protein was obtained in fish fed 35% CP diet. Muscle fat was comparable (P>0.05) among fish receiving formulated diets. Ash content was not significantly (P>0.05) different among fish of different dietary groups. Moisture content in fish fed formulated diets, with the exception of 20% CP diet, did not vary significantly (P>0.05). Eggs of fish fed formulated diets contained higher CP and fat contents than those of hydrilla‐fed fish. High (P<0.05) moisture content was noted in the eggs of hydrilla‐fed fish. Ctenopharyngodon idella fed formulated diet, with a minimum of 25% CP, showed better reproductive performance than those fed hydrilla. 相似文献
9.
Amplified Fragment Length Polymorphism (AFLP) information was used for identification of mango (Mangifera indica L.) cultivars, for studying the genetic relationship among 16 mango cultivars and seven mango rootstocks and for the construction
of a genetic linkage map. Six AFLP primer combinations produced 204 clear bands and on the average 34 bands for each combination.
The average Band-Sharing between cultivars and rootstocks was 83% and 80%, respectively. The average Band-Sharing for mango
is 81%. The probability of obtaining a similar pattern for two different mango cultivars and rootstocks is 6 × 10−3and 2 × 10−3, respectively. A preliminary genetic linkage map of the mango genome was constructed, based on the progeny of a cross between
‘Keitt’ and ‘Tommy-Atkins’. This linkage map consists of 13 linkage groups and covers 161.5 cm defined by 34 AFLP markers.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Soils which have been pretreated with carbofuran can degrade the insecticide more rapidly than untreated soils, with a consequent loss of efficacy. In laboratory studies, soils pretreated with carbofuran were found to degrade the chemical more rapidly than soils which were not so pretreated. When pretreated soils were sterilised, the rate of carbofuran degradation was much reduced, indicating that most of it was due to microbial action. Incubation of pretreated soil with [phenyl-U-14C]carbofuran led to the rapid disappearance of the parent compound (3 % left after seven days). Most of the 14C was accounted for as bound residue after seven days, whilst smaller amounts were recovered as carbon dioxide, 3-hydroxycarbofuran, 3-ketocarbofuran, and an unknown metabolite. Incubation of pretreated soil with [carbonyl-14C]carbofuran led to rapid loss of the parent compound and the recovery of 73% of 14C as carbon dioxide by five days. Most of the bound 14C (>90%) arising from [phenyl-U-14C]carbofuran treatment of pretreated soil was extracted by 1 M sodium hydroxide and about half of the extracted 14C was precipitated with ‘humic acids’ after acidification. These and other results suggest that the major metabolic route for carbofuran in pretreated soils involves hydrolysis of the ester bond leading to (1) release of carbofuran phenol which rapidly binds to soil organic matter and, (2) release of the carbonyl moiety which quickly degrades to generate carbon dioxide. 相似文献