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61.
Destaillats F Berdeaux O Sébédio JL Juaneda P Grégoire S Chardigny JM Bretillon L Angers P 《Journal of agricultural and food chemistry》2005,53(5):1422-1427
Rumelenic (cis-9,trans-11,cis-15 18:3) acid is a naturally occurring conjugated isomer of alpha-linolenic acid (CLnA) in milk fat. Metabolism in rats was studied using a synthetic CLnA mixture, composed mainly by equimolar quantities of cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15 CLnA isomers. Their metabolisms were studied by feeding high quantities of CLnA (150 mg/day) for 4 days to rats that had been reared on a fatfree diet for 2 weeks. After this period, animals were sacrificed and liver and epididymal adipose tissue lipids extracted. Six metabolites of the cis-9,trans-11,cis-15 18:3 CLnA isomers were identified as being cis-7,trans-9,cis-13 16:3, cis-11,trans-13,cis-17 20:3, cis-8,cis-11,trans-13,cis-17 20:4, cis-5,cis-8,cis-11,trans-13,cis-17 20:5, cis-7,cis-10,cis-13,trans-15,cis-19 22:5, and cis-4,cis-7,cis-10,cis-13,trans-15,cis-19 22:6 acids. Two metabolites of cis-9,trans-13,cis-15 18:3 CLnA isomer were also identified by GC-MS as being cis-7,trans-11,cis-13 16:3 and cis-5,cis-8,cis-11,trans-15,cis-17 20:5. 相似文献
62.
Anne-Laure Janson Lionel Denis Mathieu Rauch Nicolas Desroy 《Journal of Soils and Sediments》2012,12(10):1568-1580
Purpose
Bioturbation is a major process influencing the functioning of benthic ecosystems. Although controlled experiments with species in monoculture or in artificial combinations have increased the knowledge about the role of biological diversity on geochemical processes, specific interactions have been neglected, making the extrapolation of experimental results to natural systems difficult. In this context, the main objective of this study was to measure the effects of a whole natural macrobenthic community on benthic oxygen uptake.Materials and methods
The relationships between macrofauna and oxygen uptakes were investigated in the estuarine system of the Seine, France, during the winter and fall according to the variability of river discharge. Four undisturbed sediment cores with associated macrofauna and overlying water were sampled at nine subtidal stations in order to perform whole core incubations and measure total oxygen uptake (TOU). Moreover, values of diffusive oxygen uptake (DOU) were obtained using microelectrode profiling and fauna-mediated oxygen uptake (FOU) was calculated as the difference between TOU and DOU. FOUs were thus linked to macrofaunal parameters; both traditional (species richness, abundance and biomass) and functional (trophic guilds and bioturbation modes).Results and discussion
The average FOU (±SD) ranged from 170?±?36 to 1,324?±?701???mol?m?2?h?1, and values represented 33 to 89?% of TOU. Each of the traditional macrofauna parameters had a significant and positive correlation with FOU. In addition, abundance, biomass and species number of some functional groups (e.g. suspension feeders and biodiffusors) were also correlated to FOU, supporting the diversity?Cstability hypothesis of McArthur (Ecology 36:533?C536, 1955). Nevertheless, the relationship between FOU and other functional groups such as conveyors illustrated the idiosyncratic nature of this hypothesis, underlining the difficulty of clearly identifying the role of a macrofaunal community on oxygen exchanges at the sediment?Cwater interface.Conclusions
Our results confirm the importance of functional biodiversity on mineralization processes as well as the need to take into account the whole community. They also suggest that future studies should focus on the functional consequences of species loss and the potential resilience of the communities as a way to maintain ecosystem processes. 相似文献63.
The recognition of phylogenetic information for evaluating conservation priorities has stressed the importance of basal taxa. The “Evolutionary Distinctiveness” index (ED) is a species-specific index that includes branch length expressed as an absolute value measured in millions of years that can be applied to a single terminal taxon in a phylogeny. The ED depends on the tree pattern, i.e. of a cladogram included into a time-scale. When calculated for the Australian lungfish (Neoceratodusforsteri), a threatened dipnoan that occurs naturally only in southeast Queensland, the ED index shows variable value according to the chosen tree. On the basis of a recently proposed phylogeny including a new fossil find from the Early Cretaceous of Thailand, the ED value reaches the highest value for piscine sarcopterygians, and for all vertebrates, and thus reinforces the “originality” of this fish. This example points out the importance of fossils in the resolution of phylogenies and beyond, in the calculation of indexes supporting conservation decisions. 相似文献
64.
Bernard Nicolardot Lamia Bouziri Fabiola Bastian Lionel Ranjard 《Soil biology & biochemistry》2007,39(7):1631-1644
The effects of location (soil surface vs. incorporated in soil) and nature of plant residues on degradation processes and indigenous microbial communities were studied by means of soil microcosms incubation in which the different soil zones influenced by decomposition i.e. residues, soil adjacent to residues (detritusphere) and distant soil unaffected by decomposition (bulk soil) were considered. Plant material decomposition, organic carbon assimilation by the soil microbial biomass and soil inorganic N dynamics were studied with 13C labelled wheat straw and young rye. The genetic structure of the community in each soil zone were compared between residue locations and type by applying B- and F-ARISA (for bacterial- and fungal-automated ribosomal intergenic spacer analysis) directly to DNA extracts from these different zones at 50% decomposition of each residue. Both location and biochemical quality affected residue decomposition in soil: 21% of incorporated 13C wheat straw and 23% left at the soil surface remained undecomposed at the end of incubation, the corresponding values for 13C rye being 1% and 8%. Residue decomposition induced a gradient of microbial activity with more labelled C incorporated into the microbial biomass of the detritusphere. The sphere of influence of the decomposing residues on the dynamics of soluble organic C and inorganic N in the different soil zones showed particular patterns which were influenced by both residue location and quality. Residue degradation stimulated particular genetic structure of microbial community with a gradient from residue to bulk soil, and more pronounced spatial heterogeneity for fungal than for bacterial communities. The initial residue quality strongly affected the resulting spatial heterogeneity of bacteria, with a significance between-zone discrimination for rye but weak discrimination between the detritusphere and bulk soil, for wheat straw. Comparison of the different detrituspheres and residue zones (corresponding to different residue type and location), indicated that the genetic structure of the bacterial and fungal communities were specific to a residue type for detritusphere and to its location for residue, leading to conclude that the detritusphere and residue corresponded to distinct trophic and functional niches for microorganisms. 相似文献
65.
Lionel Mabit Katrin Meusburger Andra-Rada Iurian Philip N. Owens Arsenio Toloza Christine Alewell 《Journal of Soils and Sediments》2014,14(3):630-636
Purpose
Many environmental investigations (empirical and modelling) and theories are based on reliable information on the depth distribution of physical, chemical and biological properties in soils and sediments. However, such depth profiles are not easy to determine using current approaches, and, consequently, new devices are needed that are able to sample soils and sediments at fine resolutions.Materials and methods
We have designed an economic, portable, hand-operated surface soil/sediment sampler—the Fine Increment Soil Collector (FISC)—which allows for the close control of incremental soil/sediment sampling and for easy recovery of the material collected by a simple screw-thread extraction system. This innovative sampling system was developed originally for the beryllium-7 (7Be) approach in soil and sediment redistribution research. To ensure reliable estimates of soil erosion and sediment deposition from 7Be measurements, the depth distribution of this short-lived fallout radionuclide in soil/sediment at the resolution of millimetres is a crucial requirement. This major challenge of the 7Be approach can be met by using the FISC.Results and discussion
We demonstrate the usefulness of the FISC by characterising the depth distribution of 7Be at increments of 2.5 mm for a soil reference site in Austria. The activity concentration of 7Be at the uppermost increment (0–2.5 mm) was ca. 14 Bq kg?1 and displayed decreasing activity with depth. Using most conventional sampling devices (i.e. the scraper-plate system), the most accurate depth increment would have been 10 mm, and the activity concentration at the surface would have been considerably lower. Consequently, coarser sampling would have influenced estimates of 7Be-derived soil erosion and deposition. The potential application for other soil/sediment properties, such as nutrients (e.g. phosphorus), contaminants and carbon are also discussed.Conclusions
By enabling soil and sediment profiles to be sampled at a depth resolution of millimetres, the FISC has the potential to provide key information when addressing several environmental and geoscientific issues, such as the precise depth distributions of soil/sediment nutrients, contaminants and biological properties. 相似文献66.
奶牛的饮水行为和饮水需要 总被引:1,自引:0,他引:1
阐述了奶牛饮水理论的基本知识:水在奶牛体内的代谢特征,奶牛对水的数量和质量的需求,奶牛饮水量的预测,奶牛的饮水习惯和关于水质的内容.总结了大量的奶牛饲养当中有关饮水管理的实践经验和理论研究结果. 相似文献
67.
Lauren E. Page Melissa A. Kubai Rachel A. Allbaugh Leila Bedos Mackenzie M. Roy Jonathan P. Mochel Lionel Sebbag 《Veterinary ophthalmology》2023,26(4):331-338
Objectives
Determine tear film kinetics with different fluorescein concentrations and repeated eye drop administration at various time intervals.Animals Studied
Six healthy Beagles.Procedures
Six experiments were conducted on separate days: single eye drop administration (control) or two separate eye drops administered at 30 s, 1, 2, 5, and 10 min intervals. For each experiment, one eye received 0.3% fluorescein solution while the other eye received 1% fluorescein solution, and tear fluid was collected with capillary tubes at 0, 1, 5, 10, 20, 30, 40, 50, 60, 90, 120, and 180 min. Fluorescein concentrations were measured using automated fluorophotometry.Results
Compared with 0.3% solution, eyes receiving 1% fluorescein solution had significantly higher tear film concentrations (p ≤ .046) and the area-under-the-fluorescein-time curve was twofold greater (p = .005). Compared with control: (i) Tear film concentrations were significantly higher for up to 20 min when repeating administration 30 s to 5 min after the first drop (p ≤ .006); (ii) The highest increase in area-under-the-curve was obtained with 2 and 5 min intervals for 0.3% (+109%–130%) and 1% solutions (+153%–157%); (iii) The highest increase in median precorneal retention time (defined as tear film concentration < 5% from baseline values) was obtained with 5 min intervals for 0.3% (55 min vs. 15 min in control) and 2–5 min intervals for 1% solutions (50 min vs. 25 min in control).Conclusions
Drug delivery to the ocular surface can be enhanced by using more concentrated formulations and/or by repeating eye drop administration 2–5 min after the first dose. 相似文献68.
The regulation of apoplastic calcium in relation to intracellular signalling in stomatal guard cells
It is now well established that calcium has a substantive role in intracellular signalling in stomatal guard cells. Much less attention has, however, been paid to the importance of maintaining an apoplastic calcium concentration which permits this mechanism to operate. Data are presented for the calcicole Leontodon hispidus, in which the xylem sap may contain over 16 mM free calcium, showing that the concentration of calcium in the guard cell apoplast may be as low as 0.10 mM. This appears to be achieved by the deposition of considerable amounts of calcium oxalate in the mesophyll, particularly in the palisade tissue. Of the calcium delivered directly into the epidermis by the transpiration stream, a large proportion is diverted into the trichomes. It seems unlikely that stomatal regulation over long distances (e.g. from root to shoot) is accomplished via apoplastic calcium, but over shorter distances (the span of a few cells in the epidermis) signalling via calcium in the apoplast is entirely feasible and it is worthy of further investigation. 相似文献
69.
William G. Amstein C. H. Metzger W. B. Ward C. L. Fitch H. G. Zuckerman Frank W. Hussey E. L. Newdick Ralph W. Donaldson J. J. Bird Lionel Harris H. O. Werner Wm. H. Martin E. V. Hardenburg W. G. Been George E. Prince Brooks D. Drain T. E. Odland Harold L. Baily 《American Journal of Potato Research》1935,12(4):97-105
70.