Variation of juvenile Atlantic salmon (Salmo salar) body composition along sedimentary links*     

P. Johnston  N. E. Bergeron 《Ecology of Freshwater Fish》2010,19(2):187-196

Johnston P, Bergeron NE. Variation of juvenile Atlantic salmon (Salmo salar) body composition along sedimentary links.
Ecology of Freshwater Fish 2010: 19: 187–196. © 2010 John Wiley & Sons A/S Abstract – The objective of this study was to determine the proximate body composition of juvenile Atlantic salmon along the sequence of aquatic habitat types created by longitudinal changes in the riverbed substrate of two rivers (i.e., sedimentary links units). Interesting trends in the body composition were observed but our initial hypothesis, that fish of the upstream sections have higher energy content, was nevertheless not verified. No common longitudinal pattern was detected in the body composition (water, lipid, energy density) along the studied rivers. Trends in the body constituents were different between age‐classes and rivers, whereas they were highly variable within‐ and among‐samples. There was however a common trend in the pattern of variations, with the coefficient of variations increasing in the downstream direction for almost all constituents, age‐classes and rivers. Potential abiotic and biotic factors that might have contributed to these observations are discussed.  相似文献   

Sexual and somatic hybridization in the genus Lactuca     

Brigitte Maisonneuve  Marie Christine Chupeau  Yannick Bellec  Yves Chupeau 《Euphytica》1955,85(1-3):281-285

Summary Various genes for disease resistance identified in wild Lactuca are difficult, even impossible to exploit in lettuce breeding, due to sexual incompatibility between L. sativa and wild Lactuca sp. We adapted two cellular biology techniques to overcome these interspecific barriers: in vitro embryo rescue and protoplast fusion. In vitro rescue of immature embryos was used successfully for sexual hybridization between L. sativa and L. virosa. Vigorous hybrid plants were produced between L. sativa and seven accessions of L. virosa. Protoplast fusion permitted the regeneration of somatic hybrids between L. sativa and either L. tatarica or L. perennis. Hybrids between L. sativa and L. tatarica were backcrossed to L. sativa.  相似文献   

Relationships between biochemical attributes (non-structural carbohydrates and phenolics) and natural durability against fungi in dry teak wood (Tectona grandis L. f.)     

Florence Bobelé Niamké  Nadine Amusant  Jean-Paul Charpentier  Gilles Chaix  Yves Baissac  Nabila Boutahar  Augustin Amissa Adima  Séraphin Kati-Coulibaly  Christian Jay-Allemand 《Annals of Forest Science》2011,68(1):201-211

• Introduction   

Non-structural carbohydrates and phenolic compounds are implicated in the natural durability of wood. In order to find the chemical traits of natural durability in teak wood, the radial distribution of phenolics compounds and non-structural carbohydrates were studied in trees ranked by contrasting natural durability class against Antrodia sp.  相似文献   

In search of a maize ideotype for cell wall enzymatic degradability using histological and biochemical lignin characterization   总被引：1，自引：0，他引：1  

Méchin V  Argillier O  Rocher F  Hébert Y  Mila I  Pollet B  Barriére Y  Lapierre C 《Journal of agricultural and food chemistry》2005,53(15):5872-5881

Grass cell wall degradability is conventionally related to the lignin content and to the ferulic-mediated cross-linking of lignins to polysaccharides. To better understand the variations in degradability, 22 maize inbred lines were subjected to image analyses of Fasga- and M?ule-stained stem sections and to chemical analyses of lignins and p-hydroxycinnamic acids. For the first time, the nearness of biochemical and histological estimates of lignin levels was established. Combination of histological and biochemical traits could explain 89% of the variations for cell wall degradability and define a maize ideotype for cell wall degradability. In addition to a reduced lignin level, such an ideotype would contain lignins richer in syringyl than in guaiacyl units and preferentially localized in the cortical region rather than in the pith. Such enrichment in syringyl units would favor wall degradability in grasses, contrary to dicots, and could be related to the fact that grass syringyl units are noticeably p-coumaroylated. This might affect the interaction capabilities of lignins and polysaccharides.  相似文献   

Radiolysis of kaempferol in water/methanol mixtures. Evaluation of antioxidant activity of kaempferol and products formed     

Marfak A  Trouillas P  Allais DP  Champavier Y  Calliste CA  Duroux JL 《Journal of agricultural and food chemistry》2003,51(5):1270-1277

Oxidative reaction between hydroxymethyl radical ((*)CH(2)OH) and kaempferol, in methanol and methanol/water mixtures, was studied by gamma-radiolysis using a (60)Co source. Radiolysis was performed with concentrations and doses ranging from 5 x 10(-)(5) M to 5 x 10(-)(3) M and from 0.5 kGy to 14 kGy, respectively. Kaempferol degradation was followed by HPLC. Results showed that (*)CH(2)OH reacts with kaempferol at the 3-OH group and produces two depsides (K1 and K2) and other products including K3. K1, K2, and K3 were identified by NMR, LC-MS, and HRMS. The kaempferol degradation pathway leading to the K1, K2, and K3 formation is proposed. It was observed that the more water concentration in the irradiation medium increases, the more K2 concentration increases. Comprehension of food preservation is not clear because many phenomena occurring during irradiation are not established. Radiolysis of kaempferol in water/methanol mixtures helps to elucidate the phenomenon and it is possible that during the treatment of nutriments by gamma-irradiation, a series of products such as depside K2 could be formed. Antioxidant properties of kaempferol radiolysis products were evaluated according to their capacity to decrease the EPR DPPH (1,1-diphenyl-2-picrylhydrazil) signal and to inhibit superoxide radicals formed by the enzyme reaction "xanthine + xanthine oxidase".  相似文献   

Electric field-induced modification of magnetism in thin-film ferromagnets     

Weisheit M  Fähler S  Marty A  Souche Y  Poinsignon C  Givord D 《Science (New York, N.Y.)》2007,315(5810):349-351

A large electric field at the surface of a ferromagnetic metal is expected to appreciably change its electron density. In particular, the metal's intrinsic magnetic properties, which are commonly regarded as fixed material constants, will be affected. This requires, however, that the surface has a strong influence on the material's properties, as is the case with ultrathin films. We demonstrated that the magnetocrystalline anisotropy of ordered iron-platinum (FePt) and iron-palladium (FePd) intermetallic compounds can be reversibly modified by an applied electric field when immersed in an electrolyte. A voltage change of -0.6 volts on 2-nanometer-thick films altered the coercivity by -4.5 and +1% in FePt and FePd, respectively. The modification of the magnetic parameters was attributed to a change in the number of unpaired d electrons in response to the applied electric field. Our device structure is general and should be applicable for characterization of other thin-film magnetic systems.  相似文献   

Constraints on neon and argon isotopic fractionation in solar wind     

Meshik A  Mabry J  Hohenberg C  Marrocchi Y  Pravdivtseva O  Burnett D  Olinger C  Wiens R  Reisenfeld D  Allton J  McNamara K  Stansbery E  Jurewicz AJ 《Science (New York, N.Y.)》2007,318(5849):433-435

To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.  相似文献   

Starch granule size variation and relationship with tuber dry matter content in heritage potato varieties     

Jichong Zhang  Agnes Murphy  Gongshe Liu  Benoit Bizimungu  Qiang Liu  Yves Leclerc  Ti Xing  Xiu-Qing Li 《Scientia Horticulturae》2011

Heritage potato varieties in Canada are historic old varieties collected from Canada and various countries before the formal establishment of the Canadian plant variety registration system and may be a valuable gene resource for beneficial traits in potato breeding and bioproducts development. Greater evaluation is the key for the enhanced use of these materials. It is unknown how much variation of starch granules occurs among Canadian heritage potato varieties. We analyzed the starch granule size of 14 potato heritage varieties held in the Canadian Plant Gene Resources collection over 2 years using a squeezed juice and microscopic method recently developed at the Potato Research Centre. The varieties demonstrated considerable variation in starch granule size and shape. The granules showed average lengths ranging from 18 μm in the variety Congo to 32 μm in ‘Russet Burbank’. The largest single granule measured from 64 μm in ‘Congo’ to 91 μm in ‘Crotte d’Ours.’ The granule sizes of the varieties showed a very high correlation (r = 0.975, P < 0.0001) between years. This high reproducibility suggests the existence of genetic factors in determining starch granule size. We also found that the starch granule size is positively correlated with tuber dry matter (in terms of specific gravity) in these heritage potatoes. The results demonstrated reproducible genotypic variation for starch granule size and shape in tubers with a significant correlation to tuber dry matter in these heritage potato varieties, and offers the possibility for and agronomic relevance of genetic modification of starch granules through selective breeding.  相似文献   

In vitro digestibility of α-casozepine, a benzodiazepine-like peptide from bovine casein, and biological activity of its main proteolytic fragment     

Cakir-Kiefer C  Le Roux Y  Balandras F  Trabalon M  Dary A  Laurent F  Gaillard JL  Miclo L 《Journal of agricultural and food chemistry》2011,59(9):4464-4472

α-Casozepine is a peptide, corresponding to the sequence 91-100 of the bovine α(s1)-casein, displaying anxiolytic activity in the rat. The α(s1)-casein tryptic hydrolysate containing this peptide decreases stress effects after oral administration in various species including man. Therefore, the stability of this peptide toward gastric and pancreatic proteases has been assessed by using pepsin, chymotrypsin/trypsin, Corolase PP, pepsin followed by chymotrypsin/trypsin or pepsin followed by Corolase PP. α-Casozepine was slowly degraded by chymotrypsin, much more sensitive to pepsin and Corolase PP but not completely destroyed after 4 h kinetics. The bonds in the region 91 to 95 of the α-casozepine were totally resistant to hydrolysis by all studied proteases. Surprisingly, a fragment, corresponding to the sequence 91-97 and found in all the hydrolysis media in significant amount, possessed an anxiolytic activity in three behavioral tests measuring this parameter. This peptide could participate in the in vivo activity of α-casozepine.  相似文献   

Antimicrobial potential of egg yolk ovoinhibitor, a multidomain Kazal-like inhibitor of chicken egg     

Bourin M  Gautron J  Berges M  Attucci S  Le Blay G  Labas V  Nys Y  Rehault-Godbert S 《Journal of agricultural and food chemistry》2011,59(23):12368-12374

Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis . The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs).  相似文献