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991.
Marit Espe Raja Mansingh Rathore Zhen-Yu Du Bjørn Liaset Adel El-Mowafi 《Amino acids》2010,39(2):449-460
The current experiment aimed to study whether interactions with lipid metabolism possibly might explain the relative increased
liver weight obtained in fish fed sub-optimal methionine levels. A basal diet based on a blend of plant proteins which is
low in methionine (1.6 g Met/16 g N) was compared to a methionine adequate diet (2.2 g Met/16 g N) prepared by adding dl-methionine (2.4 g/kg) to the basal diet in the expense of wheat grain. Fish oil was used as the lipid source. The diets were
balanced in all nutrients except methionine. The diets were fed to Atlantic salmon (500 g BW) for a period of 3 months. Feed
intake did not differ, rendering the intake of all nutrients except methionine equal. Fish fed the low methionine diet had
an increased liver size relative to body weight, indicating fat deposition in the liver. Fish given the sub-optimal methionine
diet showed about six times higher fatty acid synthase (FAS) activity as compared to the fish fed the adequate methionine
diet, indicating a higher de novo lipogenesis. A significant rise in the liver 18:1 to 18:0 fatty acid ratios also supported
storage of lipids over fatty acid oxidation. Indeed, methionine limitation resulted in significantly higher TAG concentrations
in the liver. Sub-optimal dietary methionine also resulted in lower hepatic taurine concentrations and the total bile acids
concentrations were reduced in faeces and tended to be reduced in plasma. Taken together, our data show that salmon fed sub-optimal
methionine levels had increased relative liver weight and developed signs commonly described in the early stage of non-alcoholic
fatty liver disease in rodent models (increased FAS activity, changed fatty acid ratios and TAG accumulation). 相似文献
992.
Jesper Hedal Kløverpris Kenneth Baltzer Per H. Nielsen 《The International Journal of Life Cycle Assessment》2010,15(1):90-103
Background, aims and scope
Most life cycle inventory data for crops do not include the ultimate (marginal) land use induced by crop consumption. The aims of this study were to present, document and discuss a method which can solve this problem and, furthermore, to present concrete examples for wheat consumption in Brazil, China, Denmark and the USA. A global scope is applied and the simulated adaptation to increased wheat demand corresponds to a long-term temporal scope under present market conditions with present technology. 相似文献993.
Martin Lappann Heike Claus Tessa Van Alen Morten Harmsen Johannes Elias Søren Molin Ulrich Vogel 《Molecular microbiology》2010,75(6):1355-1371
Major pathogenic clonal complexes (cc) of Neisseria meningitidis differ substantially in their point prevalence among healthy carriers. We show that frequently carried pathogenic cc (e.g. sequence type ST‐41/44 cc and ST‐32 cc) depend on extracellular DNA (eDNA) to initiate in vitro biofilm formation, whereas biofilm formation of cc with low point prevalence (ST‐8 cc and ST‐11 cc) was eDNA‐independent. For initial biofilm formation, a ST‐32 cc type strain, but not a ST‐11 type strain, utilized eDNA. The release of eDNA was mediated by lytic transglycosylase and cytoplasmic N‐acetylmuramyl‐l ‐alanine amidase genes. In late biofilms, outer membrane phospholipase A‐dependent autolysis, which was observed in most cc, but not in ST‐8 and ST‐11 strains, was required for shear force resistance of microcolonies. Taken together, N. meningitidis evolved two different biofilm formation strategies, an eDNA‐dependent one yielding shear force resistant microcolonies, and an eDNA‐independent one. Based on the experimental findings and previous epidemiological observations, we hypothesize that most meningococcal cc display a settler phenotype, which is eDNA‐dependent and results in a stable interaction with the host. On the contrary, spreaders (ST‐11 and ST‐8 cc) are unable to use eDNA for biofilm formation and might compensate for poor colonization properties by high transmission rates. 相似文献
994.
Andreas Jørgensen Lufanna C. H. Lai Michael Z. Hauschild 《The International Journal of Life Cycle Assessment》2010,15(1):5-16
Background, aim and scope
Assuming that the goal of social life cycle assessment (SLCA) is to assess damage and benefits on its ‘area of protection’ (AoP) as accurately as possible, it follows that the impact pathways, describing the cause effect relationship between indicator and the AoP, should have a consistent theoretical foundation so the inventory results can be associated with a predictable damage or benefit to the AoP. This article uses two concrete examples from the work on SLCA to analyse to what extent this is the case in current practice. One considers whether indicators included in SLCA approaches can validly assess impacts on the well-being of the stakeholder, whereas the other example addresses whether the ‘incidence of child labour’ is a valid measure for impacts on the AoPs. 相似文献995.
Jürgen Geisler Takashi Suzuki Hildegunn Helle Yasuhiro Miki Shuji Nagasaki Nhat K. Duong Dagfinn Ekse Turid Aas Dean B. Evans Per E. Lønning Hironobu Sasano 《The Journal of steroid biochemistry and molecular biology》2010,118(4-5):237-241
Breast cancer tissue estrogen levels on an average exceed plasma as well as benign breast tissue levels. To evaluate the contribution of intra-tumor aromatization to individual tumor estrogen levels (estradiol, E2; estrone, E1; estrone sulfate, E1S), breast cancer tissue sections obtained during mastectomy in 28 postmenopausal breast cancer patients were stained for aromatase protein expression using the aromatase antibody 677. The findings were correlated to intra-tumor estrogen levels determined with a highly sensitive HPLC-RIA. Staining with 677 alone (irrespective of the hormone receptor status) revealed no difference in tumor E2 levels comparing 677+ versus 677? tumors, although a non-significant trend towards higher tumor E1 and E1S levels was observed in 677+ breast cancers. In contrast, tumor levels of E2 were significantly higher in ER+ tumors compared to ER? tumors (P < 0.001) and to benign breast tissue from the same breast (P < 0.001). Analysing the additional effect of positive staining with the aromatase antibody 677 on tumor estrogen levels in the subgroup of ER+ tumors, revealed significantly higher tumor levels of E2 (mean level of 544.7 versus 197.1 fmol/g tissue) as well as a non-significant trend concerning tumor E1 (mean level of 296.9 versus 102.1 fmol/g tissue). The mean tumor tissue E1S level was observed somewhat lower in ER+677+ (103.5 fmol/g) versus ER+677? tumors (190.1 fmol/g). In the subgroup of ER+PgR+ tumors, tissue levels of E2 were also found to be significantly higher among 677+ compared to 677? tumors: 873.2 fmol/g (95% CI 395.9–1925.6) versus 217.9 fmol/g (95% CI 88.8–534.9) (P = 0.015).In conclusion, our results indicate a moderate effect of aromatase enzyme expression evaluated by IHC using the antibody 677 on intra-tumor estrogen levels among ER+ breast cancers. A substantial interindividual variation in the ratios between the individual estrogen fractions suggests additional effects, like alterations in other enzymes to be involved in the intra-tumor estrogen homeostasis. 相似文献
996.
Magnus Kjaergaard Ann‒Beth Nørholm Ruth Hendus‒Altenburger Stine F. Pedersen Flemming M. Poulsen Birthe B. Kragelund 《Protein science : a publication of the Protein Society》2010,19(8):1555-1564
Structural characterization of intrinsically disordered proteins (IDPs) is mandatory for deciphering their potential unique physical and biological properties. A large number of circular dichroism (CD) studies have demonstrated that a structural change takes place in IDPs with increasing temperature, which most likely reflects formation of transient α-helices or loss of polyproline II (PPII) content. Using three IDPs, ACTR, NHE1, and Spd1, we show that the temperature-induced structural change is common among IDPs and is accompanied by a contraction of the conformational ensemble. This phenomenon was explored at residue resolution by multidimensional NMR spectroscopy. Intrinsic chemical shift referencing allowed us to identify regions of transiently formed helices and their temperature-dependent changes in helicity. All helical regions were found to lose rather than gain helical structures with increasing temperature, and accordingly these were not responsible for the change in the CD spectra. In contrast, the nonhelical regions exhibited a general temperature-dependent structural change that was independent of long-range interactions. The temperature-dependent CD spectroscopic signature of IDPs that has been amply documented can be rationalized to represent redistribution of the statistical coil involving a general loss of PPII conformations. 相似文献
997.
998.
Serene Hargreaves Nigel Maxted Ryoko Hirano Michael Abberton Leif Skøt Brian V. Ford-Lloyd 《Conservation Genetics》2010,11(4):1317-1326
Island populations are often thought to be more susceptible to the loss of genetic diversity as a consequence of limited population
size and genetic drift, greater susceptibility to detrimental stochastic events and low levels of immigration. However the
geographic isolation of islands may create refuges for native crop species whose genetic diversity is threatened from the
genetic erosion occurring in mainland areas as a result of crop-wild gene flow and genetic swamping. Many UK islands remain
uncharacterised in terms of plant genetic diversity. In this study we compared the genetic diversity of mainland populations
and landraces of Trifolium repens with wild populations collected from the islands surrounding the UK, including the island of Hirta in the St Kildan archipelago.
Individuals from St Kilda represent a unique conservation resource, with populations both highly differentiated from UK mainland
populations and genetically distinct from cultivated varieties, whilst able to retain diversity through limited human influence
on the islands. In contrast, there is relative genetic similarity of wild UK populations to cultivated forms highlighted in
mainland populations, but with geographic barriers preventing complete homogenisation of the mainland UK genepool. We underline
the need for conservation priorities to include common species that are threatened by gene flow from cultivation, and draw
attention to the potential of islands to preserve natural levels of genetic diversity. 相似文献
999.
A basic premise of conservation geneticists is that low levels of genetic variation are associated with fitness costs in terms
of reduced survival and fecundity. These fitness costs may frequently vary with environmental factors and should increase
under more stressful conditions. However, there is no consensus on how fitness costs associated with low genetic variation
change under natural conditions in relation to the stressfulness of the environment. On the Swedish west coast, natterjack
toad Bufo calamita populations show a strong population genetic structure and large variation in the amount of within-population genetic variation.
We experimentally examined the survival of natterjack larvae from six populations with different genetic variation in three
thermal environments corresponding to (a) the mean temperature of natural ponds (stable, laboratory), (b) a high temperature
environment occurring in desiccating ponds (stable, laboratory) and (c) an outdoor treatment mimicking the natural, variable
thermal conditions (fluctuating, semi-natural). We found that larvae in the outdoor treatment had poorer survival than larvae
in the stable environments suggesting that the outdoor treatment was more stressful. Overall, populations with higher genetic
variation had higher larval survival. However, a significant interaction between treatments and genetic variation indicated
that fitness costs associated with low genetic variation were less severe in the outdoor treatment. Thus, we found no support
for the hypothesis that fitness costs associated with low genetic variation increase under more stressful conditions. Our
results suggest that natural thermal stress may mask fitness losses associated with low genetic variation in these populations. 相似文献
1000.
E. Banguera-Hinestroza A. Bjørge R. J. Reid P. Jepson A. R. Hoelzel 《Conservation Genetics》2010,11(5):1823-1836
In this paper we use mitochondrial and microsatellite DNA variation to investigate the mechanisms that underlie the evolution
of population structure in a highly mobile marine mammal, the white-beaked dolphin. We found moderate genetic diversity (h) at mtDNA, but low nucleotide diversity (π) (0.7320 ± 0.0031 and 0.0056 ± 0.0004, respectively), consistent with expectations
for a recent expansion. Analyses based on mismatch distributions further suggested a demographic expansion in the Norwegian-Barents
Sea population and a spatial expansion in the British isles-North Sea population, implying distinct demographic histories.
F
ST values showed clear differentiation among these two populations, but no difference was found between putative populations
separated by the English Channel. Our data suggest a stepwise pattern of expansion, dependent on available coastal habitat.
The conservation implications are a need to protect local populations isolated by an expanse of deep water, and in particular,
a population along the British coasts and in the North Sea as separate from the North Norway-Barents Sea population. It is
also evident that overall diversity was reduced, probably during the last glacial epoch. 相似文献