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31.

Background

Winter migration of immature brown trout (Salmo trutta) into freshwater rivers has been hypothesized to result from physiologically stressful combinations of high salinity and low temperature in the sea.

Results

We sampled brown trout from two Danish populations entering different saline conditions and quantified expression of the hsp70 and Na/K-ATPases α 1b genes following acclimation to freshwater and full-strength seawater at 2°C and 10°C. An interaction effect of low temperature and high salinity on expression of both hsp70 and Na/K-ATPase α 1b was found in trout from the river entering high saline conditions, while a temperature independent up-regulation of both genes in full-strength seawater was found for trout entering marine conditions with lower salinities.

Conclusion

Overall our results support the hypothesis that physiologically stressful conditions in the sea drive sea-run brown trout into freshwater rivers in winter. However, our results also demonstrate intra-specific differences in expression of important stress and osmoregulative genes most likely reflecting adaptive differences between trout populations on a regional scale, thus strongly suggesting local adaptations driven by the local marine environment.  相似文献   
32.
The filamentous fungus Gliocladium virens is able to produce fructooligosaccharides (FOS), fructose-containing sugars, used as functional ingredients to improve nutritional and technological properties of foods. In this work we evaluated FOS production by G. virens when grown in a wide range of sucrose concentrations (10–400 g l?1). High sucrose concentrations increased both biomass and FOS production, including 6-kestose, a trisaccharide comprising β (2 → 6) linked fructosyl units, with enhanced stability and prebiotic activity when compared to the typical FOS β (2 → 1) linked. The highest 6-kestose yield (3 g l?1) was achieved in media containing 150 g l?1 sucrose after 4–5 days of culture, production being 90% greater than in media containing 10, 30, or 50 g l?1 sucrose. After 5 days, FOS production declined markedly, following complete sucrose depletion in the medium. Although most of the β-fructofuranosidases preferentially catalyze sucrose hydrolysis, FOS production in G. virens grown in high sucrose concentration, might be attributed to a reverse hydrolysis by these enzymes. In conclusion, high sucrose concentrations increase growth of G. virens whilst 6-kestose accumulation in the medium seems to be controlled both by specific properties of β-fructofuranosidases and on the sucrose concentration.  相似文献   
33.
1. Benthic macroinvertebrates (MI) are commonly used to assess freshwater ecosystems with the reference condition approach. Such assessments necessitate control for natural community variation, either by categorical typologies or by predictive models that have been widely and successfully developed for running water biota but not previously for lake profundal invertebrates. 2. We evaluated four modelling techniques [multivariate regression tree (MRT), limiting environmental differences, nonparametric multiplicative regression (NPMR) and River Invertebrate Prediction And Classification System (RIVPACS) and the operative Finnish lake typology for assessing taxonomic completeness (observed‐to‐expected number of taxa, O/E) of profundal MI assemblages. We used data from 74 and 33 minimally disturbed reference lake basins for calibration and validation of the approaches, respectively, and 72 test basins subject to various anthropogenic pressures to evaluate sensitivity to detect impact. Either all predicted taxa (threshold probability of capture Pt = 0+) or only those predicted to be captured with ≥0.25 probability were used to calculate O/E. 3. With Pt = 0.25, all four modelling approaches were accurate (mean O/E = 0.966–1.053) but imprecise (SD of O/E = 0.279–0.304) in predicting the fauna actually observed in validation sites. All models were subtly more precise than a null model (mean 1.038, SD 0.343) or the typology (1.046, 0.327). The taxon‐specific NPMR model was slightly more precise than the other three models based on site groupings. 4. The O/E values correlated relatively weakly (r = 0.55–0.86) among the approaches, which thus produced contrasting lake‐specific assessments, despite their seemingly comparable performances. Indeed, typology, suggesting that MI assemblages were impaired in 56% of test sites, was more sensitive than the other approaches (26–46%) as an indicator of human‐induced deterioration. However, this greater ostensible sensitivity seemed to be biased, as lake morphometry, a main driver of natural community variation, remained uncontrolled by the typology. 5. Generally, our exercise illustrates the inconclusiveness of the common validation criteria for the assessment methods. The apparent poor predictability of the profundal fauna, irrespective of the method, may partly stem from large observation error, which could be alleviated by more intensive sampling. However, instead of an O/E‐taxa index, some other metric encompassing quantitative aspects might be preferable for assessing these species‐poor communities.  相似文献   
34.
A series of secondary face modified cyclodextrins (CDs) were synthesised with the aim of constructing host molecules capable of forming host-guest complexes with neuromuscular blockers, especially with rocuronium bromide. Perfacial 2-O-substitution of gamma-CD with 4-carboxybenzyl resulted in a CD host molecule 1 that forms a 1:1 binary complex with rocuronium bromide (K(a) 6.2 x 10(5) M(-1)). The biological activities of this compound and other derivatives as reversal agents of rocuronium bromide were examined in vitro (mouse hemi-diaphragm) and in vivo (anaesthetized guinea pigs). The host molecule 1 was found to exert potent reversal activity (ED(50) 0.21 micromol/kg, iv) against rocuronium-induced neuromuscular block, and thus proved the viability of using host molecules as antidotes of a biologically active compound.  相似文献   
35.
Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomineLutzomyia longipalpis and in some midwestern regions byLutzomyia cruzi. Studies of the phlebotomine fauna, feedinghabits and natural infection rate by Leishmania contribute toincreased understanding of the epidemiological chain of leishmaniases and theirvectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70%Lu. cruzi and 20.52% Lutzomyia whitmani).Lu. cruzi females were identified by observing the shapes of thecibarium (a portion of the mouthpart) and spermatheca, from which samples wereobtained for polymerase chain reaction to determine the rates of natural infection.Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. Amoderate correlation was discovered between the number of Lu. cruziand the temperature and the minimum rate of infection was 6.10%. Twenty-two femaleswere reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). Weconclude that Lu. cruzi and Lu. whitmani haveadapted to the urban environment in this region and that Lu. cruziis the most likely vector of VL in Jaciara. Moreover, maintenance ofLeishmania in the environment is likely aided by the presence ofbirds and domestic and synanthropic animals.  相似文献   
36.
To develop agents for radionuclide imaging Aβ plaques in vivo, we prepared three fluorine-substituted analogs of arylbenzothiazole class; compound 2 has a high affinity for Aβ (K(i)=5.5nM) and the specific binding to Aβ in fluorescent staining. In preparation for the synthesis of these arylbenzothiazole analogs in radiolabeled form as an Aβ plaques-specific positron emission tomography (PET) imaging probe, we investigated synthetic route suitable for its labeling with the short-lived PET radionuclide fluorine-18 (t(1/2)=110min) and diaryliodonium tosylate precursors (12, 13a-e and 14). 2-Aryl-6-[(18)F]fluorobenzothiazoles ([(18)F]1-3) were synthesized in efficiently short reaction times (40-60min) with high radiochemical yields (19-40%), purities (>95%) and specific activities (85-118GBq/μmol). Tissue distribution studies showed that high radioactivity of [(18)F]2 accumulated in the brain with rapid clearance in healthy mice. Radioactive metabolites were analyzed in brain samples of mice and corresponded to 81% of parent remained by 30min after a tail-vein injection. These results suggest that [(18)F]2 is a promising probe for evaluation of Aβ plaques imaging in brain using PET.  相似文献   
37.
SJ Swanson  PC Bethke    RL Jones 《The Plant cell》1998,10(5):685-698
Light microscopy was used to study the structure and function of vacuoles in living protoplasts of barley (Hordeum vulgare cv Himalaya) aleurone. Light microscopy showed that aleurone protoplasts contain two distinct types of vacuole: the protein storage vacuole and a lysosome-like organelle, which we have called the secondary vacuole. Fluorescence microscopy using pH-sensitive fluorescent probes and a fluorogenic substrate for cysteine proteases showed that both protein storage vacuoles and secondary vacuoles are acidic, lytic organelles. Ratio imaging showed that the pH of secondary vacuoles was lower in aleurone protoplasts incubated in gibberellic acid than in those incubated in abscisic acid. Uptake of fluorescent probes into intact, isolated protein storage vacuoles and secondary vacuoles required ATP and occurred via at least two types of vanadate-sensitive, ATP-dependent tonoplast transporters. One transporter catalyzed the accumulation of glutathione-conjugated probes, and another transported probes not conjugated to glutathione.  相似文献   
38.
 Aims Desertification results in ecological and biological diminution of the earth, and can happen naturally or cause by anthropogenic activities. This process especially affects arid and semi-arid regions, such as the Isfahan region, where the spread of desertification is reaching critical proportions. The aim of this study is to use remotely sensed data to review the trend of desertification in the northern of Isfahan, Iran. Methods Multi-temporal images were employed to evaluate the trend of desertification, specifically the TM and ETM+ data of September, 1990 and September, 2001. Geometric and radiometric corrections were applied to each image prior to image processing and supervised classification, and vegetation indices were applied to produce a land use map of each image in nine classes. The land use classification s in the two map images were compared and changes between land use classes were detected over the 11 year period using a fuzzy and post-classification technique. Important findings The maps and their comparison with false color composite images showed the differences efficiently. With the fuzzy and post-classification method the land use changes were sited on the map. Fuzzy confirmed 53% changed area and 47% unchanged areas in the study region. The results verify the desertification expansion in the study areas. Because of poor land management, agricultural lands converted to desert and abandoned areas, and some marginal pasture lands had to be changed to agricultural land which are desertification spreading according to United Nations Conference on Desertification (UNCOD). Also farmland and pastures have been converted to urban and industrial areas, and the rangelands have been spoiled due to opencast mine excavations. With the mine margins eroding as well as their debris accumulating on the pasture lands, desertification has become worse. Three areas of less-elevated mountains have remained unchanged. This study confirmed that the anthropogenic activities accelerated the desertification process and severely endangered the remaining areas.  相似文献   
39.
In this article, we report the synthesis of Na2Sr1‐x(PO4)F:Eux phosphor via a combustion method. The influence of different annealing temperatures on the photoluminescence properties was investigated. The phosphor was excited at both 254 and 393 nm. Na2Sr1‐x(PO4)F:Eux3+ phosphors emit strong orange and red color at 593 and 612 nm, respectively, under both excitation wavelengths. Na2Sr1‐x(PO4)F:Eux3+ phosphors annealed at 1050°C showed stronger emission intensity compared with 600, 900 and 1200°C. Moreover, Na2Sr1‐x(PO4)F:Eux3+ phosphor was found to be more intense when compared with commercial Y2O3:Eu3+ phosphor. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
40.
Bacterial infection a leading cause of death among patients with stroke, with elderly patients often presenting with more debilitating outcomes. The findings from our retrospective study, supported by previous clinical reports, showed that increasing age is an early predictor for developing fatal infectious complications after stroke. However, exactly how and why older individuals are more susceptible to infection after stroke remains unclear. Using a mouse model of transient ischaemic stroke, we demonstrate that older mice (>12 months) present with greater spontaneous bacterial lung infections compared to their younger counterparts (7–10 weeks) after stroke. Importantly, we provide evidence that older poststroke mice exhibited elevated intestinal inflammation and disruption in gut barriers critical in maintaining colonic integrity following stroke, including reduced expression of mucin and tight junction proteins. In addition, our data support the notion that the localized pro‐inflammatory microenvironment driven by increased tumour necrosis factor‐α production in the colon of older mice facilitates the translocation and dissemination of orally inoculated bacteria to the lung following stroke onset. Therefore, findings of this study demonstrate that exacerbated dysfunction of the intestinal barrier in advanced age promotes translocation of gut‐derived bacteria and contributes to the increased risk to poststroke bacterial infection.  相似文献   
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