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81.
82.
K. Blue Pahl David J. Yurkowski Sabine P. Wintner Geremy Cliff Matthew L. Dicken Nigel E. Hussey 《Journal of fish biology》2021,98(3):829-841
Stable-isotope analysis (SIA) provides a valuable tool to address complex questions pertaining to elasmobranch ecology. Liver, a metabolically active, high turnover tissue (~166 days for 95% turnover), has the potential to reveal novel insights into recent feeding/movement behaviours of this diverse group. To date, limited work has used this tissue, but ecological application of SIA in liver requires consideration of tissue preparation techniques given the potential for high concentrations of urea and lipid that could bias δ13C and δ15N values (i.e., result in artificially lower δ13C and δ15N values). Here we investigated the effectiveness of (a) deionized water washing (WW) for urea removal from liver tissue and (b) chloroform-methanol for extraction of lipids from this lipid rich tissue. We then (a) established C:N thresholds for deriving ecologically relevant liver isotopic values given complications of removing all lipid and (b) undertook a preliminary comparison of δ13C values between tissue pairs (muscle and liver) to test if observed isotopic differences correlated with known movement behaviour. Tests were conducted on four large shark species: the dusky (DUS, Carcharhinus obscurus), sand tiger (RAG, Carcharias taurus), scalloped hammerhead (SCA, Sphyrna lewini) and white shark (GRE, Carcharodon carcharias). There was no significant difference in δ15N values between lipid-extracted (LE) liver and lipid-extracted/water washed (WW) treatments, however, WW resulted in significant increases in %N, δ13C and %C. Following lipid extraction (repeated three times), some samples were still biased by lipids. Our species-specific “C:N thresholds” provide a method to derive ecologically viable isotope data given the complexities of this lipid rich tissue (C:N thresholds of 4.0, 3.6, 4.7 and 3.9 for DUS, RAG, SCA and GRE liverLEWW tissue, respectively). The preliminary comparison of C:N threshold corrected liver and muscle δ13C values corresponded with movement/habitat behaviours for each shark; minor differences in δ13C values were observed for known regional movements of DUS and RAG (δ13CDiffs = 0.24 ± 0.99‰ and 0.57 ± 0.38‰, respectively), while SCA and GRE showed greater differences (1.24 ± 0.63‰ and 1.08 ± 0.71‰, respectively) correlated to large-scale movements between temperate/tropical and pelagic/coastal environments. These data provide an approach for the successful application of liver δ13C and δ15N values to examine elasmobranch ecology. 相似文献
83.
Vinci B Duret C Klieber S Gerbal-Chaloin S Sa-Cunha A Laporte S Suc B Maurel P Ahluwalia A Daujat-Chavanieu M 《Biotechnology journal》2011,6(5):554-564
Down-regulation of detoxification genes, notably cytochrome P450 (CYPs), in primary hepatocyte cultures is a long-standing and major concern. We evaluated the influence of medium flow in this model. Hepatocytes isolated from 12 different liver donors were cultured either in a multichamber modular bioreactor (MCmB, flow rate 250-500 μL/min) or under standard/static conditions, and the expression of 32 genes, enzyme activities and biological parameters were measured 7-21 days later. mRNA expression of genes involved in xenobiotic/drug metabolism and transport, including CYP1A1, 1A2, 2B6, 2C9, 3A4 (and activities for some of them), UDP-glucuronosyltransferase (UGT) 1A1, UGT2B4, UGT2B7, glutathione S-transferase (GSTα), and multidrug resistance protein 1 (MDR1) and MRP2, were specifically up-regulated by medium flow as compared with static controls in all cultures tested. In 2-week-old cultures, expression of detoxification genes reached levels close to or higher than those measured in freshly isolated hepatocytes. In contrast, CYP2D6 and most of other tested genes were not affected by medium flow. We conclude that medium flow specifically interferes with, and up-regulates, the activity of xenosensors and/or the expression of detoxification genes in primary human hepatocytes. Down-regulation of detoxification genes in conventional (static) cultures is therefore partly a consequence of the absence of medium circulation. 相似文献
84.
Schneider RK Neuss S Stainforth R Laddach N Bovi M Knuechel R Perez-Bouza A 《Differentiation; research in biological diversity》2008,76(2):156-167
Abstract Human mesenchymal stem cells (hMSC) are able to differentiate into mature cells of various mesenchymal tissues. Recent studies have reported that hMSC may even give rise to cells of ectodermal origin. This indication of plasticity makes hMSC a promising donor source for cell-based therapies. This study explores the differentiation potential of hMSC in a tissue-specific microenvironment simulated in vitro . HMSC were cultured air-exposed on dermal equivalents (DEs) consisting of collagen types I and III with dermal fibroblasts and subjected to conditions similar to those used for tissue engineering of skin with keratinocytes. Culture conditions were additionally modified by pre-treating the cells with 5-azacytidine or supplementing the medium with all trans retinoic acid (RA). HMSC were capable of adaptation to epidermis-specific conditions without losing their mesenchymal multipotency. However, despite the viability and evident three-dimensional epidermis-like growth pattern, hMSC showed a persistent expression of mesenchymal but not of epithelial markers, thus indicating a lack of epidermal (trans) differentiation. Further, electron microscopy and immunohistochemical analyses demonstrated that hMSC cultured under epidermis-specific conditions adopted a myofibroblastic phenotype and function, promoted in particular by air exposure. In conclusion, multipotent hMSC failed to differentiate into E-cadherin- or cytokeratin-expressing cells under optimized organotypic culture conditions for keratinocytes but differentiated into myofibroblast-like cells contracting the extracellular matrix, a phenomenon that was enhanced by RA and 5-azacytidine. These results indicate that hMSC might contribute to wound-healing processes by extracellular matrix reorganization and wound contraction but not by differentiation into keratinocytes. 相似文献
85.
Günther Klonner Johannes Wessely Andreas Gattringer Dietmar Moser Iwona Dullinger Karl Hülber Sabine B. Rumpf Svenja Block Oliver Bossdorf Marta Carboni Luisa Conti Wayne Dawson Emily Haeuser Martin Hermy Tamara Münkemüller Madalin Parepa Wilfried Thuiller Sebastiaan Van der Veken Kris Verheyen Mark van Kleunen Franz Essl Stefan Dullinger 《Ecography》2019,42(9):1548-1557
Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level. 相似文献
86.
87.
Sandra Blanco Sabine Dietmann Joana V Flores Shobbir Hussain Claudia Kutter Peter Humphreys Margus Lukk Patrick Lombard Lucas Treps Martyna Popis Stefanie Kellner Sabine M Hölter Lillian Garrett Wolfgang Wurst Lore Becker Thomas Klopstock Helmut Fuchs Valerie Gailus‐Durner Martin Hrabĕ de Angelis Ragnhildur T Káradóttir Mark Helm Jernej Ule Joseph G Gleeson Duncan T Odom Michaela Frye 《The EMBO journal》2014,33(18):2020-2039
88.
Characterization of the carboxysomal carbonic anhydrase CsoSCA from Halothiobacillus neapolitanus
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Heinhorst S Williams EB Cai F Murin CD Shively JM Cannon GC 《Journal of bacteriology》2006,188(23):8087-8094
In cyanobacteria and many chemolithotrophic bacteria, the CO(2)-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is sequestered into polyhedral protein bodies called carboxysomes. The carboxysome is believed to function as a microcompartment that enhances the catalytic efficacy of RubisCO by providing the enzyme with its substrate, CO(2), through the action of the shell protein CsoSCA, which is a novel carbonic anhydrase. In the work reported here, the biochemical properties of purified, recombinant CsoSCA were studied, and the catalytic characteristics of the carbonic anhydrase for the CO(2) hydration and bicarbonate dehydration reactions were compared with those of intact and ruptured carboxysomes. The low apparent catalytic rates measured for CsoSCA in intact carboxysomes suggest that the protein shell acts as a barrier for the CO(2) that has been produced by CsoSCA through directional dehydration of cytoplasmic bicarbonate. This CO(2) trap provides the sequestered RubisCO with ample substrate for efficient fixation and constitutes a means by which microcompartmentalization enhances the catalytic efficiency of this enzyme. 相似文献
89.
Margarita Torrent Blanca Llompart Sabine Lasserre-Ramassamy Immaculada Llop-Tous Miriam Bastida Pau Marzabal Ann Westerholm-Parvinen Markku Saloheimo Peter B Heifetz M Dolors Ludevid 《BMC biology》2009,7(1):5-14
Background
Protein bodies (PBs) are natural endoplasmic reticulum (ER) or vacuole plant-derived organelles that stably accumulate large amounts of storage proteins in seeds. The proline-rich N-terminal domain derived from the maize storage protein γ zein (Zera) is sufficient to induce PBs in non-seed tissues of Arabidopsis and tobacco. This Zera property opens up new routes for high-level accumulation of recombinant proteins by fusion of Zera with proteins of interest. In this work we extend the advantageous properties of plant seed PBs to recombinant protein production in useful non-plant eukaryotic hosts including cultured fungal, mammalian and insect cells. 相似文献90.
Nitrous oxide and methane fluxes of a pristine slope mire in the German National Park Harz Mountains
Nadine Tauchnitz Rainer Brumme Sabine Bernsdorf Ralph Meissner 《Plant and Soil》2008,303(1-2):131-138
Pristine peatlands covered by Histosols (bogs and fens) with high water table and a restricted oxygen (O2) availability are known to have low emissions of nitrous oxide (N2O) but may be a significant source for atmospheric methane (CH4) which are both important greenhouse gases. For the first time N2O and CH4 fluxes of a pristine slope mire in the German Harz Mountains have been monitored. Previously reported peatlands are characterised
by anaerobic conditions due to high water table levels. Slope mires monitored here receive O2 through slope water inflow. Gas fluxes have been monitored deploying closed chamber method on a central non-forested area
and a forested area at the periphery of the slope mire. By means of groundwater piezometers water table levels, ammonium and
nitrate contents as well as hydro-chemical variables like oxygen content and redox potential of the mire pore water have been
concurrently measured with trace gas fluxes at both monitoring sites of the slope mire. The slope mire took up small amounts
of atmospheric methane at a rate of −0.02 ± 0.01 kg C ha−1 year−1 revealing no significant difference between the forested and non-forested site. Higher uptake rates were observed during
low water table level. In contrast to pristine peatlands influx of oxygen containing pore water into slope mire does limit
reduction processes and resultant CH4 emission. N2O fluxes of the forested and non-forested sites of the slope mire did not differ and amounted to 0.25 ± 0.44 kg N ha−1 year−1. Higher emissions were observed at low water table levels and during thawing periods. In spite of favourable conditions N2O fluxes of the slope mire have been comparable to those of pristine peatlands. 相似文献