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1.
Payant V; Abukashawa S; Sasseville M; Benkel BF; Hickey DA; David J 《Molecular biology and evolution》1988,5(5):560-567
Nuclear DNA was extracted from each of the eight species comprising the
Drosophila melanogaster species subgroup. Southern hybridization of this
DNA by using a molecular probe specific for the alpha-amylase coding region
showed that the duplicated structure of the amylase locus, first found in
D. melanogaster, is conserved among all species of the melanogaster
subgroup. Evidence is also presented for the concerted evolution of the
duplicated genes within each species. In addition, it is shown that the
glucose repression of amylase gene expression, which has been extensively
studied in D. melanogaster, is not confined to this species but occurs in
all eight members of the species subgroup. Thus, both the duplicated gene
structure and the glucose repression of Drosophila amylase gene activity
are stable over extended periods of evolutionary time.
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2.
A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques 总被引:2,自引:2,他引:0 下载免费PDF全文
HA Lester ME Krouse MM Nass NH Wassermann BF Erlanger 《The Journal of general physiology》1980,75(2):207-232
After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules. 相似文献
3.
Microorganisms originating from a soil contaminated by low levels of polycyclic aromatic hydrocarbons (PAHs) were enriched
with three- and four-ring PAHs as primary substrates in the presence of benzo[a]pyrene (BaP). Most enrichment cultures, isolated in the presence or absence of a sorptive matrix, significantly transformed
BaP. Evidence of BaP mineralization was obtained with cultures enriched on phenanthrene and anthracene. Our findings supplement
literature data suggesting the wide occurrence of microbial activity against BaP. Journal of Industrial Microbiology & Biotechnology (2002) 28, 70–73 DOI: 10.1038/sj/jim/7000211
Received 11 December 2000/ Accepted in revised form 04 September 2001 相似文献
4.
Narayana PB Fazolini André LS Cruz Miriam BF Werneck Jo?o PB Viola Clarissa M Maya-Monteiro Patrícia T Bozza 《Cell cycle (Georgetown, Tex.)》2015,14(16):2667-2676
Accumulating evidence suggests that obesity and enhanced inflammatory reactions are predisposing conditions for developing colon cancer. Obesity is associated with high levels of circulating leptin. Leptin is an adipocytokine that is secreted by adipose tissue and modulates immune response and inflammation. Lipid droplets (LD) are organelles involved in lipid metabolism and production of inflammatory mediators, and increased numbers of LD were observed in human colon cancer. Leptin induces the formation of LD in macrophages in a PI3K/mTOR pathway-dependent manner. Moreover, the mTOR is a serine/threonine kinase that plays a key role in cellular growth and is frequently altered in tumors. We therefore investigated the role of leptin in the modulation of mTOR pathway and regulation of lipid metabolism and inflammatory phenotype in intestinal epithelial cells (IEC-6 cells). We show that leptin promotes a dose- and time-dependent enhancement of LD formation. The biogenesis of LD was accompanied by enhanced CXCL1/CINC-1, CCL2/MCP-1 and TGF-β production and increased COX-2 expression in these cells. We demonstrated that leptin-induced increased phosphorylation of STAT3 and AKT and a dose and time-dependent mTORC activation with enhanced phosphorilation of the downstream protein P70S6K protein. Pre-treatment with rapamycin significantly inhibited leptin effects in LD formation, COX-2 and TGF-β production in IEC-6 cells. Moreover, leptin was able to stimulate the proliferation of epithelial cells on a mTOR-dependent manner. We conclude that leptin regulates lipid metabolism, cytokine production and proliferation of intestinal cells through a mechanism largely dependent on activation of the mTOR pathway, thus suggesting that leptin-induced mTOR activation may contribute to the obesity-related enhanced susceptibility to colon carcinoma. 相似文献
5.
Marijn Rutgers Daniël BF Saris Wouter JA Dhert Laura B Creemers 《Arthritis research & therapy》2010,12(3):R114
Introduction
Intraarticular administration of autologous conditioned serum (ACS) recently demonstrated some clinical effectiveness in treatment of osteoarthritis (OA). The current study aims to evaluate the in vitro effects of ACS on cartilage proteoglycan (PG) metabolism, its composition and the effects on synovial fluid (SF) cytokine levels following intraarticular ACS administration. 相似文献6.
Anika I Tsuchida Michiel Beekhuizen Marieke C ‘t Hart Timothy RDJ Radstake Wouter JA Dhert Daniel BF Saris Gerjo JVM van Osch Laura B Creemers 《Arthritis research & therapy》2014,16(5)
Introduction
This study aimed to evaluate whether profiles of several soluble mediators in synovial fluid and cartilage tissue are pathology-dependent and how their production is related to in vitro tissue formation by chondrocytes from diseased and healthy tissue.Methods
Samples were obtained from donors without joint pathology (n = 39), with focal defects (n = 65) and osteoarthritis (n = 61). A multiplex bead assay (Luminex) was performed measuring up to 21 cytokines: Interleukin (IL)-1α, IL-1β, IL-1RA, IL-4, IL-6, IL-6Rα, IL-7, IL-8, IL-10, IL-13, tumor necrosis factor (TNF)α, Interferon (IFN)γ, oncostatin M (OSM), leukemia inhibitory factor (LIF), adiponectin, leptin, monocyte chemotactic factor (MCP)1, RANTES, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), vascular growth factor (VEGF).Results
In synovial fluid of patients with cartilage pathology, IL-6, IL-13, IFNγ and OSM levels were higher than in donors without joint pathology (P ≤0.001). IL-13, IFNγ and OSM were also different between donors with cartilage defects and OA (P <0.05). In cartilage tissue from debrided defects, VEGF was higher than in non-pathological or osteoarthritic joints (P ≤0.001). IL-1α, IL-6, TNFα and OSM concentrations (in ng/ml) were markedly higher in cartilage tissue than in synovial fluid (P <0.01). Culture of chondrocytes generally led to a massive induction of most cytokines (P <0.001). Although the release of inflammatory cytokines was also here dependent on the pathological condition (P <0.001) the actual profiles were different from tissue or synovial fluid and between non-expanded and expanded chondrocytes. Cartilage formation was lower by healthy unexpanded chondrocytes than by osteoarthritic or defect chondrocytes.Conclusions
Several pro-inflammatory, pro-angiogenic and pro-repair cytokines were elevated in joints with symptomatic cartilage defects and/or osteoarthritis, although different cytokines were elevated in synovial fluid compared to tissue or cells. Hence a clear molecular profile was evident dependent on disease status of the joint, which however changed in composition depending on the biological sample analysed. These alterations did not affect in vitro tissue formation with these chondrocytes, as this was at least as effective or even better compared to healthy chondrocytes. 相似文献7.
Chimpanzee fetal G gamma and A gamma globin gene nucleotide sequences provide further evidence of gene conversions in hominine evolution 总被引:5,自引:0,他引:5
The fetal globin genes G gamma and A gamma from one chromosome of a
chimpanzee (Pan troglodytes) were sequenced and found to be closely similar
to the corresponding genes of man and the gorilla. These genes contain
identical promoter and termination signals and have exons 1 and 2 separated
by the conserved short intron 1 (122 bp) and exons 2 and 3 separated by the
more rapidly evolving, larger intron 2 (893 bp and 887 bp in chimpanzee G
gamma and A gamma, respectively). Each intron 2 has a stretch of simple
sequence DNA (TG)n serving possibly as a "hot spot" for recombination. The
two chimpanzee genes encode polypeptide chains that differ only at position
136 (glycine in G gamma and alanine in A gamma) and that are identical to
the corresponding human chains, which have aspartic acid at position 73 and
lysine at 104 in contrast to glycine and arginine at these respective
positions of the gorilla A gamma chain. Phylogenetic analysis by the
parsimony method revealed four silent (synonymous) base substitutions in
evolutionary descent of the chimpanzee G gamma and A gamma codons and none
in the human and gorilla codons. These Homininae (Pan, Homo, Gorilla)
coding sequences evolved at one-tenth the average mammalian rate for
nonsynonymous and one-fourth that for synonymous substitutions. Three
sequence regions that were affected by gene conversions between chimpanzee
G gamma and A gamma loci were identified: one extended 3' of the hot spot
with G gamma replaced by the A gamma sequence, another extended 5' of the
hot spot with A gamma replaced by G gamma, and the third conversion
extended from the 5' flanking to the 5' end of intron 2, with G gamma
replaced here by the A gamma sequence. A conversion similar to this third
one has occurred independently in the descent of the gorilla genes. The
four previously identified conversions, labeled C1-C4 (Scott et al. 1984),
were substantiated with the addition of the chimpanzee genes to our
analysis (C1 being shared by all three hominines and C2, C3, and C4 being
found only in humans). Thus, the fetal genes from all three of these
hominine species have been active in gene conversions during the descent of
each species.
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8.
Comparative ecophysiology of CAM and C3 bromeliads. III. Environmental influences on CO2 assimilation and transpiration 总被引:11,自引:8,他引:3
H. GRIFFITHS U. LÜTTGE K.-H. STIMMEL C. E. CROOK N. M. GRIFFITHS ‡ J. A. C. SMITH § 《Plant, cell & environment》1986,9(5):385-393
Abstract Field measurements of the gas exchange of epiphytic bromeliads were made during the dry season in Trinidad in order to compare carbon assimilation with water use in CAM and C3 photosynthesis. The expression of CAM was found to be directly influenced by habitat and microclimate. The timing of nocturnal CO2 uptake was restricted to the end of the dark period in plants found at drier habitats, and stomatal conductance in two CAM species was found to respond directly to humidity or temperature. Total night-time CO2 uptake, when compared with malic-acid formation (measured as the dawn-dusk difference in acidity, ΔH+), could only account for 10–40% of the total ΔH+ accumulated. The remaining malic acid must have been derived from the refixation of respired CO2 (recycling). Within the genus Aechmea (12 samples from four species), recycling was significantly correlated with night temperature at the six sample sites. Recycling was lowest in A. fendleri (54% of ΔH+ derived from respired CO2), a CAM bromeliad with little water-storage parenchyma that is restricted to wetter, cooler regions of Trinidad. Gas-exchange rates of C3 bromeliads were found to be similar to those of the CAM bromeliads, with CO2 uptake from 1 to 3 μmol m?2 s?1 and stomatal conductances generally up to 100 mmol m?2 s?1. The midday depression of photosynthesis occurred in exposed habitats, although photosynthetically active radiation (PAR) limited photosynthesis in shaded habitats. CO2 uptake of the C3 bromeliad Guzmania lingulata was saturated at around 500 μmol m?2 s?1 PAR, suggesting that epiphytic plants found in the shaded forest understorey are shade-tolerant rather than shade-demanding. Transpiration ratios (TR) during CO2 fixation in CAM (Phase I and IV) and C3 bromeliads were compared at different sites in order to assess the efficiency of water utilization. For the epiphytes displaying marked uptake of CO2, TR were found to be lower than many previously published values. In addition, the average TR values were very similar for dark CO2 uptake in CAM (42 ± 41, n= 12), Phase IV of CAM (69 ± 36, n= 3) and for C3 photosynthesis (99 ± 73, n= 4) in these plants. It appears that recycling of respired CO2 by CAM bromeliads and efficient use of water in all phases of CO2 uptake are physiological adaptations of bromeliads to arid microclimates in the humid tropics. 相似文献
9.
10.
Kemmer D Huang Y Shah SP Lim J Brumm J Yuen MM Ling J Xu T Wasserman WW Ouellette BF 《Genome biology》2005,6(12):R106
We developed Ulysses as a user-oriented system that uses a process called Interolog Analysis for the parallel analysis and
display of protein interactions detected in various species. Ulysses was designed to perform such Interolog Analysis by the
projection of model organism interaction data onto homologous human proteins, and thus serves as an accelerator for the analysis
of uncharacterized human proteins. The relevance of projections was assessed and validated against published reference collections.
All source code is freely available, and the Ulysses system can be accessed via a web interface . 相似文献