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131.
Elias DA Tollaksen SL Kennedy DW Mottaz HM Giometti CS McLean JS Hill EA Pinchuk GE Lipton MS Fredrickson JK Gorby YA 《Archives of microbiology》2008,189(4):313-324
High-throughput analyses that are central to microbial systems biology and ecophysiology research benefit from highly homogeneous
and physiologically well-defined cell cultures. While attention has focused on the technical variation associated with high-throughput
technologies, biological variation introduced as a function of cell cultivation methods has been largely overlooked. This
study evaluated the impact of cultivation methods, controlled batch or continuous culture in bioreactors versus shake flasks,
on the reproducibility of global proteome measurements in Shewanella
oneidensis MR-1. Variability in dissolved oxygen concentration and consumption rate, metabolite profiles, and proteome was greater in
shake flask than controlled batch or chemostat cultures. Proteins indicative of suboxic and anaerobic growth (e.g., fumarate
reductase and decaheme c-type cytochromes) were more abundant in cells from shake flasks compared to bioreactor cultures, a finding consistent with
data demonstrating that “aerobic” flask cultures were O2 deficient due to poor mass transfer kinetics. The work described herein establishes the necessity of controlled cultivation
for ensuring highly reproducible and homogenous microbial cultures. By decreasing cell to cell variability, higher quality
samples will allow for the interpretive accuracy necessary for drawing conclusions relevant to microbial systems biology research. 相似文献
132.
133.
Response of Litter Decomposition to Simulated N Deposition in Disturbed, Rehabilitated and Mature Forests in Subtropical China 总被引:15,自引:1,他引:15
The response of decomposition of litter for the dominant tree species in disturbed (pine), rehabilitated (pine and broadleaf
mixed) and mature (monsoon evergreen broadleaf) forests in subtropical China to simulated N deposition was studied to address
the following hypothesis: (1) litter decomposition is faster in mature forest (high soil N availability) than in rehabilitated/disturbed
forests (low soil N availability); (2) litter decomposition is stimulated by N addition in rehabilitated and disturbed forests
due to their low soil N availability; (3) N addition has little effect on litter decomposition in mature forest due to its
high soil N availability. The litterbag method (a total of 2880 litterbags) and N treatments: Control-no N addition, Low-N:
−5 g N m−2 y−1, Medium-N: −10 g N m−2 y−1, and High-N: −15 g N m−2 y−1, were employed to evaluate decomposition. Results indicated that mature forest, which has likely been N saturated due to both long-term high N deposition in the region
and the age of the ecosystem, had the highest litter decomposition rate, and exhibited no significant positive and even some
negative response to nitrogen additions. However, both disturbed and rehabilitated forests, which are still N limited due
to previous land use history, exhibited slower litter decomposition rates with significant positive effects from nitrogen
additions. These results suggest that litter decomposition and its responses to N addition in subtropical forests of China
vary depending on the nitrogen status of the ecosystem. 相似文献
134.
Angela Brieger Boris Adryan Fabian Wolpert Sandra Passmann Stefan Zeuzem Jörg Trojan 《Proteomics》2010,10(18):3343-3355
The involvement of MLH1 in several mismatch repair‐independent cellular processes has been reported. In an attempt to gain further insight into the protein's cellular functions, we screened for novel interacting partners of MLH1 utilizing a bacterial two‐hybrid system. Numerous unknown interacting proteins were identified, suggesting novel biological roles of MLH1. The network of MLH1 and its partner proteins involves a multitude of cellular processes. Integration of our data with the “General Repository for Interaction Datasets” highlighted that MLH1 exhibits relationships to three interacting pairs of proteins involved in cytoskeletal and filament organization: Thymosin β 4 and Actin γ, Cathepsin B and Annexin A2 as well as Spectrin α and Desmin. Coimmunoprecipitation and colocalization experiments validated the interaction of MLH1 with these proteins. Differential mRNA levels of many of the identified proteins, detected by microarray analysis comparing MLH1‐deficient and ‐proficient cell lines, support the assumed interplay of MLH1 and the identified candidate proteins. By siRNA knock down of MLH1, we demonstrated the functional impact of MLH1–Actin interaction on filament organization and propose that dysregulation of MLH1 plays an essential role in cytoskeleton dynamics. Our data suggest novel roles of MLH1 in cellular organization and colorectal cancerogenesis. 相似文献
135.
Guigal N Rodriguez M Cooper RN Dromaint S Di Santo JP Mouly V Boutin JA Galizzi JP 《The Journal of biological chemistry》2002,277(49):47407-47411
Uncoupling protein-3 (UCP3), which is expressed abundantly in skeletal muscle, is one of the carrier proteins dissipating the transmitochondrial electrochemical gradient as heat and has therefore been implicated in the regulation of energy metabolism. Myoblasts or differentiated muscle cells in vitro expressed little if any UCP3, compared with the levels detected in biopsies of skeletal muscle. In the present report, we sought to investigate UCP3 mRNA expression in human muscle generated by myoblast transplantation in the skeletal muscle of an immunodeficient mouse model. Time course experiments demonstrated that 7-8 weeks following transplantation fully differentiated human muscle fibers were formed. The presence of differentiated human muscle fibers was assessed by quantitative PCR measurement of the human alpha-actin mRNA together with immunohistochemical staining using specific antibodies for spectrin and the slow adult myosin heavy chain. Interestingly, we found that the expression of UCP3 mRNA was dependant on human muscle differentiation and that the UCP3 mRNA level was comparable with that found in human muscle biopsies. Moreover, the human UCP3 (hUCP3) promoter seems to be fully functional, since triiodothyronine treatment of the mice not only stimulated the mouse UCP3 (mUCP3) mRNA expression but also strongly stimulated the hUCP3 mRNA expression in human fibers formed after myoblast transplantation. To our knowledge, this is the first time that primary myoblasts could be induced to express the UCP3 gene at a level comparable of that found in human muscle fibers. 相似文献
136.
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
137.
A retained intron in the 3′‐UTR of Calm3 mRNA mediates its Staufen2‐ and activity‐dependent localization to neuronal dendrites 下载免费PDF全文
138.
O'Shea RD Lau CL Farso MC Diwakarla S Zagami CJ Svendsen BB Feeney SJ Callaway JK Jones NM Pow DV Danbolt NC Jarrott B Beart PM 《Neurochemistry international》2006,48(6-7):604-610
Excitatory amino acid transporters (EAATs) are responsible for homeostasis of extracellular L-glutamate, and the glial transporters are functionally dominant. EAAT expression or function is altered in acute and chronic neurological conditions, but little is known about the regulation of EAATs in reactive astroglia found in such neuropathologies. These studies examined the effects of the bacterial endotoxin lipopolysaccharide (LPS) on glial EAATs in vitro. The effects of LPS (1 microg/ml, 24-72 h) on EAAT activity and expression were examined in primary cultures of mouse astrocytes. [(3)H]D-aspartate uptake increased to 129% of control by 72 h treatment with LPS. Saturation analysis revealed that apparent K(m) was unchanged whilst V(max) was significantly increased to 172% of control by 72 h LPS treatment. Biotinylation and Western blotting indicated that cell-surface expression of GLT-1 was significantly elevated (146% control) by LPS treatment whereas GLAST expression was unchanged. Confocal analyses revealed that LPS treatment resulted in cytoskeletal changes and stellation of astrocytes, with rearrangement of F-actin (as shown by phalloidin labelling). Immunocytochemistry revealed clustering of GLAST, and increased expression and redistribution of GLT-1 to the cell-surface following treatment with LPS. Similar experiments were conducted in microglia, where LPS (50 ng/ml) was found to up-regulate expression of GLT-1 at 24 and 72 h in concert with cytoskeletal changes accompanying activation. These findings suggest an association of cytoskeletal changes in glia with EAAT activity, with the predominant adaptation involving up-regulation and redistribution of GLT-1. 相似文献
139.
Nectar robbing: a common phenomenon mainly determined by accessibility constraints,nectar volume and density of energy rewards 下载免费PDF全文
Nectar robbers use a hole made in the perianth to extract nectar. Since robbers may modify plant fitness, they play an important role by driving evolution on floral traits, shaping population structure and influencing community dynamics. Although nectar robbing is widespread in angiosperms, the causes and ecological implications of this behaviour on large ecological scales are still unexplored. Our aim is to study the frequency of nectar robbing in plants of temperate and tropical regions and examine its association with plant traits. We characterised the levels of nectar robbing in 88 species of Mediterranean, Alpine, Antillean and Andean plant communities and identified the most important nectar robbers. We analysed associations between the levels of robbing and floral morphology, production and density of energy rewards, mechanisms of protection against nectar robbers, plant life form and geographic origin. Nectar robbing was present at all sampling sites. Within communities two patterns of robbing levels related to the diversity and specialization of robbers were detected. In most communities one plant species presented very high levels of robbing while other species had intermediate to low robbing levels. There, nectar robbers are opportunists, robbing highly rewarding plants. In the Andean community the high specialization of several co‐existing flowerpiercers produced an even pattern of robbing levels in the plant community. Plants with long flowers, abundant nectar and a high energy density are more likely to be robbed by both insects and birds. A high aggregation of the flowers within the plants and the presence of long calyxes and bracts are associated to low robbing rates by insects and to a lesser extent by birds. Besides the morphological constraints that operate on a single flower basis, nectar robbing is a phenomenon dependent upon the density of energy rewards reflecting the presence of mechanisms on higher ecological scales. 相似文献
140.
Tomlinson ID Mason JN Blakely RD Rosenthal SJ 《Bioorganic & medicinal chemistry letters》2006,16(17):4664-4667
Compounds capable of inhibiting the dopamine transporter protein (DAT) that can be conjugated to cadmium selenide/zinc sulfide/core shell nanocrystals may be used to image the location and distribution of the DAT in neuronal cell membranes. This letter describes the synthesis of biotinylated analogs of the DAT antagonists GBR 12909 and GBR 12935 that can be attached to streptavidin coated cadmium selenide/zinc sulfide/core shell nanocrystals. 相似文献