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851.
Baoquan Bao Hung The Dang Ping Zhang Jongki Hong Chong-O. Lee Hee Young Cho Jee H. Jung 《Bioorganic & medicinal chemistry letters》2009,19(21):6205-6208
In the course of our search for bioactive metabolites from a colonial tunicate of the family Polyclinidae, six new (1–6) cyclic fatty acid derivatives were isolated. Their planar structures were established on the basis of NMR and MS spectroscopic analyses. The relative configuration was determined by NOESY experiment. Compounds 1–6 represent a fused bicyclic skeleton possibly derived from α,ω-dicarboxylic acids such as eicosanedioic acid or docosanedioic acid via a Diels–Alder type of cyclization. Compounds 1–4 and 6 showed mild cytotoxicity against a panel of five human solid tumor cell lines. 相似文献
852.
Hengtao Zhang Jeremy Parker Neal Shepherd Tony L Creazzo 《Journal of biomedical science》2009,16(1):104-13
Background
Background K+ channels are the principal determinants of the resting membrane potential (RMP) in cardiac myocytes and thus, influence the magnitude and time course of the action potential (AP).Methods
RT-PCR and in situ hybridization are used to study the distribution of TASK-1 and whole-cell patch clamp technique is employed to determine the functional expression of TASK-1 in embryonic chick heart.Results
Chicken TASK-1 was expressed in the early tubular heart, then substantially decreased in the ventricles by embryonic day 5 (ED5), but remained relatively high in ED5 and ED11 atria. Unlike TASK-1, TASK-3 was uniformly expressed in heart at all developmental stages. In situ hybridization studies further revealed that TASK-1 was expressed throughout myocardium at Hamilton-Hamburger stages 11 and 18 (S11 &; S18) heart. In ED11 heart, TASK-1 expression was more restricted to atria. Consistent with TASK-1 expression data, patch clamp studies indicated that there was little TASK-1 current, as measured by the difference currents between pH 8.4 and pH 7.4, in ED5 and ED11 ventricular myocytes. However, TASK-1 current was present in the early embryonic heart and ED11 atrial myocytes. TASK-1 currents were also identified as 3 μM anandamide-sensitive currents. 3 μM anandamide reduced TASK-1 currents by about 58% in ED11 atrial myocytes. Zn2+ (100 μM) which selectively inhibits TASK-3 channel at this concentration had no effect on TASK currents. In ED11 ventricle where TASK-1 expression was down-regulated, IK1 was about 5 times greater than in ED11 atrial myocytes.Conclusion
Functional TASK-1 channels are differentially expressed in the developing chick heart and TASK-1 channels contribute to background K+ conductance in the early tubular embryonic heart and in atria. TASK-1 channels act as a contributor to background K+ current to modulate the cardiac excitability in the embryonic heart that expresses little IK1. 相似文献853.
Camellia, comprising more than 200 species, is the type genus of the family Theaceae. Currently, the interspecies relationship of the economically important genus is still a matter of great debate and controversy. In an attempt to help settle this dispute using molecular phylogeny, we analyzed ITS sequences of 112 species of Camellia. The maximum parsimony and Bayesian trees grouped these species into eight major clades and four isolates. The current study supported the monophyly of sections Thea and Furfuracea, a merged section of Theopsis and Eriandra and the formation of section Oleifera by H, -t. Chang (Flora of Reipulicae Popularis Sinicae. Tomus 49 (3), Science Press, China). The study suggested the polyphyletic nature of the sections Camellia, Paracamellia, Pseudocamellia, and Tuberculata and the paraphyletic nature of the section Chrysantha but did not support the sectional status of the three small sections, Archecamellia, Piquetia, and Sterocarpus. We also discuss the results in terms of morphology, geographic distribution and the results from an earlier molecular phylogeny analysis. 相似文献
854.
Stereoselective differences in pharmacokinetics between clausenamide (CLA) enantiomers have been found after intravenous and oral administration of each enantiomer to rats. The differences could be associated with protein binding of CLA enantiomers. By equilibrium dialysis methods, the binding of CLA enantiomers to rat plasma protein was investigated. The results showed that mean percentages of (-) and (+)CLA in the bound form were 28.5% and 38.0%, respectively, indicating that the unbound fraction of (-)CLA was higher than that of (+)CLA, which provided an explanation for stereoselective pharmacokinetics of CLA enantiomers in rats. The results also showed that there were species differences in plasma protein binding of (-)-isomer between rats (28.5%) and rabbits (47.2%). Furthermore, effects of plasma protein binding on the distribution of CLA enantiomers to their possible target tissues were observed. The amount of (-)CLA in brain was greater than that of (+)CLA 15 min after administration of each enantiomer to rats. But the results were reverse at 4 h postdose. Further studies in distributional kinetics showed that (-)CLA had a more rapid absorption and distribution to hippocampus, cortex, and cerebellum than (+) CLA. (+)CLA had greater values for T(max), t(1/2) (beta), and AUC(0) (-->infinity), and smaller ones for CL/F and V(d)/F than its antipode. The data indicated that the distribution of (-) and (+)CLA in their target tissues was stereoselective. The stereoselective distribution might be involved in the metabolism and transport of two enantiomers in the central nerve system. 相似文献
855.
Although nitrate is a macronutrient and can serve as good nitrogen source for many species of phytoplankton, high nitrate
concentrations do not benefit the growth of phytoplankton. We hypothesise that algae cultured under high nitrate concentrations
can accumulate intracellular nitrite, which is produced by nitrate reductase (NR) and can inhibit the growth of algae. To
assess the validity of this hypothesis, Microcystis aeruginosa was grown under different nitrate concentrations from 3.57 to 21.43 mM in low CO2 and high CO2 conditions for 15 days. We observed that, with increasing nitrate concentrations, the intracellular nitrite concentrations
of the alga increased and the growth rates and photosynthesis declined. When grown under high CO2 conditions, M. aeruginosa showed lower intracellular nitrite concentrations and higher growth rates and
\textP\textm\textchla {\text{P}}_{\text{m}}^{{\text{chl}}a} ,
\textR\textd\textchla {\text{R}}_{\text{d}}^{{\text{chl}}a} , αchla
than under low CO2 conditions. These results suggest that the accumulation of intracellular nitrite could be the cause of inhibition of algal
growth under high nitrate concentrations. 相似文献
856.
FANCJ/BRIP1 encodes a helicase that has been implicated in the maintenance of genomic stability. Here, to better understand
FANCJ function in DNA damage responses, we have examined the regulation of its cellular localization. FANCJ nuclear foci assemble
spontaneously during S phase and are induced by various stresses. FANCJ foci colocalize with the replication fork following
treatment with hydroxyurea, but not spontaneously. Using FANCJ mutants, we find that FANCJ helicase activity and the capacity
to bind BRCA1 are both involved in FANCJ recruitment. Given similarities to the recruitment of another Fanconi anemia protein,
FANCD2, we tested for colocalization of FANCJ and FANCD2. Importantly, these proteins show substantial colocalization, and
FANCJ promotes the assembly of FANCD2 nuclear foci. This process is linked to the proper localization of FANCJ itself since
both FANCJ and FANCD2 nuclear foci are compromised by FANCJ mutants that abrogate its helicase activity or interaction with
BRCA1. Our results suggest that FANCJ is recruited in response to replication stress and that FANCJ/BRIP1 may serve to link
FANCD2 to BRCA1. 相似文献
857.
Background
Extensive mononuclear cell infiltration is strongly correlated with liver damage in patients with chronic hepatitis B virus (CHB) infection. Macrophages and infiltrating monocytes also participate in the development of liver damage and fibrosis in animal models. However, little is known regarding the immunopathogenic role of peripheral blood monocytes and intrahepatic macrophages.Methodology/Principal Findings
The frequencies, phenotypes, and functions of peripheral blood and intrahepatic monocyte/macrophage subsets were analyzed in 110 HBeAg positive CHB patients, including 32 immune tolerant (IT) carriers and 78 immune activated (IA) patients. Liver biopsies from 20 IA patients undergoing diagnosis were collected for immunohistochemical analysis. IA patients displayed significant increases in peripheral blood monocytes and intrahepatic macrophages as well as CD16+ subsets, which were closely associated with serum alanine aminotransferase (ALT) levels and the liver histological activity index (HAI) scores. In addition, the increased CD16+ monocytes/macrophages expressed higher levels of the activation marker HLA-DR compared with CD16− monocytes/macrophages. Furthermore, peripheral blood CD16+ monocytes preferentially released inflammatory cytokines and hold higher potency in inducing the expansion of Th17 cells. Of note, hepatic neutrophils also positively correlated with HAI scores.Conclusions
These distinct properties of monocyte/macrophage subpopulations participate in fostering the inflammatory microenvironment and liver damage in CHB patients and further represent a collaborative scenario among different cell types contributing to the pathogenesis of HBV-induced liver disease. 相似文献858.
Rong Pan Lixiang Cao Haiwei Huang Renduo Zhang Yu Mo 《Applied microbiology and biotechnology》2010,88(4):997-1005
In this study, dried and humid fruiting bodies of Tremella fuciformis and Auricularia polytricha were examined as cost-effective biosorbents in treatment of heavy metals (Cd2+, Cu2+, Pb2+, and Zn2+) in aqueous solution. The humid T. fuciformis showed the highest capacity to adsorb the four metals in the multi-metal solutions. The Pb2+ adsorption rates were 85.5%, 97.8%, 84.8%, and 91.0% by dried T. fuciformis, humid T. fuciformis, dried A. polytricha, and humid A. polytricha, respectively. The adsorption amount of Pb2+ by dried and humid T. fuciformis in Cd2+ + Pb2+, Cu2+ + Pb2+, Pb2+ + Zn2+, Cd2+ + Cu2+ + Pb2+, and Cd2+ + Zn2+ + Pb2+ solutions were not lower than that in Pb2+ solutions. The results suggested that in humid T. fuciformis, Cd2+, Cu2+, and Zn2+ promoted the Pb2+ adsorption by the biomass. In the multi-metal solutions of Cd2+ + Cu2+ + Pb2+ + Zn2+, the adsorption amount and rates of the metals by all the test biosorbents were in the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. Compared with the pseudo first-order model, the pseudo second-order model described the adsorption kinetics much better,
indicating a two-step biosorption process. The present study confirmed that fruiting bodies of the jelly fungi should be useful
for the treatment of wastewater containing Cd2+, Cu2+, Pb2+, and Zn2+. 相似文献
859.
A major QTL for resistance to Gibberella stalk rot in maize 总被引:1,自引:0,他引:1
Qin Yang Guangming Yin Yanling Guo Dongfeng Zhang Shaojiang Chen Mingliang Xu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,121(4):673-687
Fusarium graminearum Schwabe, the conidial form of Gibberella zeae, is the causal fungal pathogen responsible for Gibberella stalk rot of maize. Using a BC1F1 backcross mapping population derived from a cross between ‘1145’ (donor parent, completely resistant) and ‘Y331’ (recurrent
parent, highly susceptible), two quantitative trait loci (QTLs), qRfg1 and qRfg2, conferring resistance to Gibberella stalk rot have been detected. The major QTL qRfg1 was further confirmed in the double haploid, F2, BC2F1, and BC3F1 populations. Within a qRfg1 confidence interval, single/low-copy bacterial artificial chromosome sequences, anchored expressed sequence tags, and insertion/deletion
polymorphisms, were exploited to develop 59 markers to saturate the qRfg1 region. A step by step narrowing-down strategy was adopted to pursue fine mapping of the qRfg1 locus. Recombinants within the qRfg1 region, screened from each backcross generation, were backcrossed to ‘Y331’ to produce the next backcross progenies. These
progenies were individually genotyped and evaluated for resistance to Gibberella stalk rot. Significant (or no significant) difference in resistance reactions between homozygous and heterozygous genotypes
in backcross progeny suggested presence (or absence) of qRfg1 in ‘1145’ donor fragments. The phenotypes were compared to sizes of donor fragments among recombinants to delimit the qRfg1 region. Sequential fine mapping of BC4F1 to BC6F1 generations enabled us to progressively refine the qRfg1 locus to a ~500-kb interval flanked by the markers SSR334 and SSR58. Meanwhile, resistance of qRfg1 to Gibberella stalk rot was also investigated in BC3F1 to BC6F1 generations. Once introgressed into the ‘Y331’ genome, the qRfg1 locus could steadily enhance the frequency of resistant plants by 32–43%. Hence, the qRfg1 locus was capable of improving maize resistance to Gibberella stalk rot. 相似文献
860.
Ju-Hong Zhang Li-Wen Sun Lin-Lin Liu Jie Lian Shao-Li An Xu Wang Jing Zhang Jun-Ling Jin Shan-Yu Li Jing-Hui Xi 《Plant Molecular Biology Reporter》2010,28(2):324-333
In this study, comparative proteomics was used to investigate the interaction of Spodoptera exigua and Arabidopsis thaliana. By using 2-D electrophoresis of differentially expressed proteins, combined with high-throughput matrix-assisted laser desorption/ionization
time of flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF/TOF MS, the changes in the abundance of proteins induced by
insect feeding were studied in A. thaliana. More than 1,100 protein spots were reproducibly detected on each gel. The intensities of 30 protein spots in particular
changed significantly, showing differences in volume of at least twofold. Among these, 17 protein spots were upregulated,
and 13 were downregulated following an 8-h insect feeding period. Nineteen insect-feeding-responsive proteins were identified,
all of which were involved in metabolic regulation, binding functions or cofactor requirement of protein, cell rescue, and
defense and virulence, as assessed by Munich Information Center for Protein Sequences function category. About 50% of these
were involved in metabolism, including transketolase, S-adenosylmethionine synthase 3, 2,3-biphosphoglycerate-independent phosphoglycerate mutase, beta-ureidopropionase, GDP-d-mannose 3′,5′-epimerase, and fatty acid synthase. The identification of insect-feeding-responsive proteins on Arabidopsis provides not only new insights into insect stress but also a good start for further investigation of their functions. Understanding
how the plant responses to insects in the proteomic level will provide tools for a better management of insect pest in the
field. 相似文献