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排序方式: 共有163条查询结果,搜索用时 15 毫秒
41.
Ahmed SH 《Science (New York, N.Y.)》2004,306(5703):1901-1902
42.
Moïse Nola Thomas Njiné Norbert Kemka Serge H. Zébazé Togouet Samuel Foto Menbohan Adolphe Monkiedje Pierre Servais Mohamed Messouli Claude Boutin 《Water, air, and soil pollution》2006,171(1-4):253-271
Groundwater protection from pollutants depends mostly on retention potentials of soil above groundwater table. Soil separating soil surface from groundwater table is made up of several layers and can be divided into different columns along its vertical transect. Wastewater percolation tests were carried out through one soil column CA, in contact with soil surface and through another CB, closely above groundwater table. The aim of the study was to assess the importance of soil columns CA and CB, in total coliforms and staphylococci retention during wastewater infiltration or groundwater recharge, in equatorial soils in Central African region. The results showed that, the fraction of total coliforms retained through soil column CA varied with respect to wastewater loads applied on top of soil column, from 69.22% to 99.95%, relative to the total coliforms concentration deposited on top. The fraction of total coliforms retained through CB varied with respect to wastewater loads applied, from 96.98 to 99.89% relative to the total coliforms deposited on top. Through both soil columns, fractions of staphylococci retained was in the order of 99.99% relative to the total staphylococci concentration deposited on top. For the whole bacteriological analysis, the fractions of total coliforms retained seems to be greater through deeper soil column than that of upper soil column. The bacterial contaminants retained relative to their concentrations in wastewater poured on soil column surfaces, varied from 6.17 log units to 9.73 log units. An applied load of 100 ml seemed to lead to the bacterial pollutants transported through both soil columns studied. NH4 + was retained by fractions varying from 97.37 to 98.74%. Concentrations of various contaminants found in groundwater would be a tiny part, relative to quantities deposited on soil surface. Bacterial retention potentials of soil column separating soil surface from groundwater table during wastewater percolation, varies along its transect. It would be due to numerous and variable physical, chemical and structural properties of soil layers and bacteria on the one hand, and to results of various interactions between soil layer particles and cell bacteria, on the other hand. 相似文献
43.
László Sági Serge Remy Bert Verelst Bart Panis Bruno P. A. Cammue Guido Volckaert Rony Swennen 《Euphytica》1955,85(1-3):89-95
Summary In order to introduce currently-available genes with agronomical value into banana, two genetic transformation protocols have been optimized.Firstly, regenerable protoplasts isolated from embryogenic cell suspensions of the cultivar Bluggoe have been used for the introduction of several chimaeric uidA gene constructs by electroporation. With the inclusion of polyethylene glycol and heat shock, the frequency of transiently expressing protoplasts reached 1.8% as shown by an in situ -glucuronidase assay. A duplicated 35S promoter with an alfalfa mosaic virus leader sequence (pBI-426) induced the highest expression rate among the constructs tested.Embryogenic cell suspensions of cv. Bluggoe have also been bombarded with accelerated particles coated with a high expression uidA gene construct (pEmuGN) using a biolistic gun. After a partial optimization of the procedure, transient GUS assays reproducibly demonstrated the presence of 400 blue foci in 30 l of settled cell volume (approximately 25 mg cells). Selection and characterization of antibiotic-resistant transformed cultures is in progress.Abbreviations AMV
alfalfa mosaic virus
- GUS
-glucuronidase
- TGE
transient GUS expression
-
uidA
gene for -glucuronidase 相似文献
44.
Summary Deterioration of cotton, Gossypium hirsutum L., seed can adversely affect stands, seedling vigor, and subsequent performance of plants, but deterioration can be lessened by improved genetic resistance. This study was conducted to evaluate the relationship of physical and germination characteristics of cotton seed and to determine the inheritance of resistance to seed deterioration. Physical (weight, volume, density, and imbibition rate) and germination (germination of non-deteriorated seed and deteriorated seed) characteristics were determined for eight cotton genotypes. In addition, imbibition rate and the germination characteristics were determined for all possible F1, including reciprocals, combinations of the eight genotypes. Variation among the parents for germination of deteriorated seed and imbibition rate were significantly, highly correlated (r=–0.97) and intrinsically related. Resistance to seed deterioration tended to increase as seed weight and volume decreased. Significant genetic effects were found for imbibition rate and germination of both non-deteriorated and deteriorated seed. However, general combining ability (GCA) accounted for only 21% of the variation in crosses sums of squares for germination of non-deteriorated seed. In contrast, GCA accounted for 90% of the variation for germination of deteriorated seed and imbibition rate. A breeding approach involving selection of early generation seed for ability to survive hot water treatment, then evaluating later generations for imbibition rate is suggested as a means to improve resistance to seed deterioration in cotton. 相似文献
45.
Seaman Dave J. I. Voigt Maria Bocedi Greta Travis Justin M. J. Palmer Stephen C. F. Ancrenaz Marc Wich Serge Meijaard Erik Bernard Henry Deere Nicolas J. Humle Tatyana Struebig Matthew J. 《Landscape Ecology》2021,36(10):2957-2975
Landscape Ecology - Agricultural expansion is a leading cause of deforestation and habitat fragmentation globally. Policies that support biodiversity and facilitate species movement across farmland... 相似文献
46.
Christopher L. Brown Serge I. Doroshov Michael D. Cochran Howard A. Bern 《Fish physiology and biochemistry》1989,7(1-6):295-299
Elevation of the triiodothyronine (T3) content of striped bass (Morone saxatilis) eggs by maternal T3 injection confirms the uptake of T3 by oocytes. The resulting offspring were influenced favorably by the T3, as seen in quantitative indices of development. As reported previously, larvae from T3-supplemented eggs raised under laboratory conditions exhibited increased body area, length, dry weight, and rates of swimbladder
inflation and survival, compared to controls. Also, the T3 content of unfertilized oocytes correlated positively and highly significantly with survival to two weeks of age within individual
cohorts (Brownet al., 1988). In the present study, the survival of experimental and control striped bass was monitored through the fingerling
stage, under hatchery production conditions. The rate of recovery of maternally T3-treated cohorts from pond-culture was approximately fourfold that of controls. The striking effects of T3 enrichment of eggs on offspring indicate the potential contribution of maternal hormones in striped bass development, and
suggest possible applications in aquaculture. 相似文献
47.
Bernard Breton Tomasz Mikolajczyk Jean-Michel Danger Francis Gonnet Serge Saint-Pierre Hubert Vaudry 《Fish physiology and biochemistry》1989,7(1-6):77-83
This work investigated the action of neuropeptide Y (NPY) on thein vitro pituitary release of the maturing gonadotropic hormone (GtH) of the rainbow trout using a perifusion system employing trout
balanced salt solution (pH 7.5) at 15°C and a 12.5 ml/h flow rate. In vitellogenic females a 20 minutes NPY application (10−7 M) induced a 20–30% decrease in GtH secretion. Removal of NPY was followed by a rebound in GTH secretion. On the contrary,
in ovulated females, NPY (15 minutes, 10−7 M) directly stimulated GTH secretion. The greatest stimulation was obtained the day of ovulation where the stimulatory effect
of NPY was similar to those induced by s.GnRH in the same conditions, reaching 400% of the basal GTH level. In vitellogenic
females treated with 1-4-6 androstadien 3–7 dione, an inhibitor of aromatase activity, the pituitary response to NPY was similar
to that obtained in ovulated females. Thus thein vitro action of NPY might depend on thein vivo steroidogenic environment. 相似文献
48.
Growth and survival of white sturgeon larvae were examined at ad libitum feeding with three commercial salmonid diets, and experimental crustacean diet, and a live food control (cubifex). The results demonstrated that some manufactured diets, particularly a semi-moist ration, can be used to rear white sturgeon during the first 40 days of feeding. Although specific growth rates of fish fed a semi-moist feed were 40% lower than those fed live foods, survival rates were similar. The high mortality previously associated with later transfer of fish from live foods to manufactured diets was avoided. Dry diets were not well accepted and resulted in lower rates of growth and survival. 相似文献
49.
50.
Foaming and Emulsifying Properties of Fractions of Gluten Peptides Obtained by Limited Enzymatic Hydrolysis and Ultrafiltration 总被引:2,自引:0,他引:2
Gluten hydrolysates were prepared by limited enzymatic hydrolysis with a protease having a chymotryptic activity in the presence or in the absence of cysteine during the dispersion phase of the process. The hydrolysates were fractionated by ultrafiltration, using two inorganic membranes with different molecular weight cut-off (MWCO), 50 kg/mol and 150 kg/mol. The retentates were enriched in hydrophobic peptides and the permeates were enriched in hydrophilic peptides. The foaming and emulsifying properties of hydrolysates, retentates and permeates were analysed at two pHs (4 and 6·5) and two salt concentrations (0·2 and 2% NaCl). Hydrolysates displayed a foaming capacity, but the foams were not stable. Permeates generated foams at pH 6·5 only, and these foams had a very short life-time. Permeates displayed no emulsifying properties. Retentates yielded foams with a good stability and were more efficient than whole hydrolysates to stabilise emulsions. They provided a strong resistance to coalescence. The functional properties of retentates were only sightly influenced by pH and ionic strength. Neither cysteine addition, which helps gluten dispersion and increases the yield of soluble hydrolysate, nor the MWCO of the ultrafiltration membranes influenced the functionality of the hydrolysate fractions. 相似文献