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61.
Similarly to higher plant root systems, Chlamydomonas reinhardtii Dangeard (UTEX 90) cells exhibited biphasic NO3? uptake kinetics. The uptake pattern was similar in cells cultured in 10 mM NO3? (NO3?-grown), 0.25 mM NO3? (N-limited) or 10 mM NO3? followed by an 18-h period of N-deprivation (N-starved). In all cell types there was an apparent phase transition in uptake at 1.1 mM NO3?, although there were variations in the uptake Vmax of both isotherms. The rate of uptake via isotherm 0 ([NO3?]<1.1 mM) in N-limited cells was higher than that of either NO3?-grown or N-starved cells. In contrast, NO3?-grown and N-limited cells exhibited comparable Vmax values when supplied with 1.1 to 1.8 mM NO3? (isotherm 1). When supplied with 1.6 mM NO3?, both N-limited and N-starved cells exhibited enhanced linear uptake after 60 min of incubation. We ascribed this to an induction phenomenon. This trend was not observed when NO3?-grown cells were supplied with 1.6 mM NO3?, or when N-limited and N-starved cells were supplied with 0.6 mM NO3?. The ‘inducible’ aspect of uptake by N-limited cells was blocked by cycloheximide (10 mg l?1), but not by actinomycin D (5 mg l?1), thus indicating the involvement of a translational or post-translational event. To investigate this phenomenon further, we analysed the cell proteins of N-limited cells supplied with either 0.6 or 1.6 mM NO3? for 90 min, using two-dimensional gel electrophoresis. Comparison of protein profiles enabled the identification of a single cell membrane-associated polypeptide (21 kDa, pI ca 5.5) and ten soluble fraction polypeptides (17–73 kDa, pI ca 5.0 to 7.1) unique to the high NO3? treatment. We propose that the ‘inducible’ portion of NO3? uptake may provide the means by which C. reinhardtii cells regulate uptake in accordance with assimilatory capacity. 相似文献
62.
崇明东滩湿地不同潮汐带入侵植物互花米草根际细菌的多样性 总被引:2,自引:0,他引:2
为了调查崇明东滩湿地入侵植物互花米草(Spartina Alterniflora)在不同潮汐带和季节根际细菌的多样性与丰富度,以本地植物芦苇、海三棱藨草(P. australis和 S.mariqueter)和光滩为对照实验研究,在崇明东滩湿地10样点采集根际土壤和光滩土壤,通过PCR-DGGE分子生物学等技术并结合传统培养方法对土壤细菌进行分析研究。研究表明:东滩湿地不同潮汐带的植物根际细菌群落丰富度和多样性不同,在夏季中潮带的根际细菌丰富度(P=0.021<0.05)较高,各个潮带的植物根际细菌在夏秋季有高多样性,其中中潮带的植物根际细菌平均多样性指数最高(H=4.20)。在中潮带入侵物种互花米草根际细菌的丰富度和多样性要显著高于本地植物芦苇和海三棱藨草,其中海三棱藨草的根际细菌在夏季略高。崇明东滩湿地入侵植物互花米草根际细菌与本地植物相比较具有较高的多样性,而且外来种互花米草对湿地土壤微生物群落结构有着较强影响;入侵种互花米草根际细菌的高丰富度和多样性可能是其成功入侵东滩湿地的一个重要因素。 相似文献
63.
Martinez Benitez E Stolz A Becher A Wolf DH 《Biochemical and biophysical research communications》2011,(3):528-532
In eukaryotes, membrane and soluble proteins of the secretory pathway enter the endoplasmic reticulum (ER) after synthesis in an unfolded state. Directly after entry, most proteins are modified with glycans at suitable glycosylation sites and start to fold. A protein that cannot fold properly will be degraded in a process called ER associated degradation (ERAD). Failures in ERAD, either by loss of function or by premature degradation of proteins, are a cause of severe diseases. Therefore, the search for novel ERAD components to gain better insight in this process is of high importance. Carbohydrate trimming is a relevant process in ER quality control. In this work a novel putative yeast mannosidase encoded by the open reading frame YLR057W was identified and named Mnl2. Deletion of MNL2 diminished the degradation efficiency of misfolded CPY* in the absence of the cognate mannosidase Mnl1, indicating a specific role in ERAD. 相似文献
64.
将KGM和Sepharose 4B凝胶在相同条件下活化、偶联接上染料Cibacron Blue F3GA制成了KGM和Sepharose 4B染料亲和吸附剂,并用来与牛血甭白蛋白(BSA)作用,每毫升KGM亲和吸附剂可吸附BSA 28mg,用NaSCN洗脱时间为84.5%,而Sepharose 4B染料样和吸附剂每毫升可吸附BSA 15.3mg,用NaSCN洗脱时间收迷81.7%,并对两种凝胶的染 相似文献
65.
Chunjiang Ye Zhanwang Yu Fanna Kong Suowei Wu Bin Wang 《Plant Molecular Biology Reporter》2005,23(2):167-177
In the present study we propose and test the concept of R-ISSR, a new tool for genomic fingerprinting, mapping, and gene tagging.
The concept is based on the fact that primers for inter-simple sequence repeat (ISSR) and random-amplified polymorphic DNA
(RAPD) analysis elicit different genomic information, and the combined use of these 2 kinds of primers in the same polymerase
chain reaction (PCR) reactions might reveal new genomic loci that could not be detected with either technique alone. The feasibility
of this tool was first electronically simulated with sequence analysis software andArabidopsis chromosome sequence. Next, different combinations of ISSR and RAPD primers were applied in real PCR reactions to detect new
genomic loci in 2 maize lines (Q319 and 1145). Sequencing gels were used to separate PCR products and showed good resolving
ability in comparison with agarose gels. RAPD primers could be successfully used with ISSR primers for the detection of new
genomic loci and applied in a new way for genomic mapping, fingerprinting, and gene tagging. 相似文献
66.
Community survey of ammonia-oxidizing bacteria in full-scale activated sludge processes with different solids retention time 总被引:7,自引:0,他引:7
Hallin S Lydmark P Kokalj S Hermansson M Sörensson F Jarvis A Lindgren PE 《Journal of applied microbiology》2005,99(3):629-640
AIMS: To study the effects of different solids retention time (SRT) on the nitrification activity and community composition of ammonia-oxidizing bacteria (AOB) in two full-scale activated sludge processes during a 5-month period. METHODS AND RESULTS: The AOB community composition was analysed using fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE), and the identified populations were enumerated by quantitative FISH. Potential nitrification rates were determined in batch tests and the in situ rates were calculated from mass balances of nitrogen in the plants. Increased SRT reduced the nitrification activity, but neither the number per mixed liquor suspended solids nor community composition of AOB were affected. Two dominant AOB populations related to Nitrosomonas europaea and Nitrosomonas oligotropha were identified by FISH, whereas only the latter could be detected by DGGE. CONCLUSIONS: The effect of a longer SRT on the activity was probably because of physiological changes in the AOB community rather than a change in community composition. SIGNIFICANCE AND IMPACT OF THE STUDY: Physiological alterations of a stable AOB community are possible and may stabilize activated sludge processes. The commonly used FISH probes designed to target all beta-proteobacterial AOB does not detect certain Nitrosomonas oligotropha populations, leading to an underestimation of AOB if a wider set of probes is not used. 相似文献
67.
Han BK Kim JN Shin JH Kim JK Jo DH Kim H Han JY 《Molecular reproduction and development》2005,72(4):521-529
The domestic chicken (Gallus gallus) is an important model for research in developmental biology because its embryonic development occurs in ovo. To examine the mechanism of embryonic germ cell development, we constructed proteome map of gonadal primordial germ cells (gPGCs) from chicken embryonic gonads. Embryonic gonads were collected from 500 embryos at 6 days of incubation, and the gPGCs were cultured in vitro until colony formed. After 7-10 days in culture, gPGC colonies were separated from gonadal stroma cells (GSCs). Soluble extracts of cultured gPGCs were then fractionated by two-dimensional gel electrophoresis (pH 4-7). A number of protein spots, including those that displayed significant expression levels, were then identified by use of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and LC-MS/MS. Of the 89 gPGC spots examined, 50 yielded mass spectra that matched avian proteins found in on-line databases. Proteome map of this type will serve as an important reference for germ cell biology and transgenic research. 相似文献
68.
Increasing evidence suggests that an inhibition of the proteasome, as demonstrated in Parkinson's disease, might be involved in Alzheimer's disease. In this disease and other Tauopathies, Tau proteins are hyperphosphorylated and aggregated within degenerating neurons. In this state, Tau is also ubiquitinated, suggesting that the proteasome might be involved in Tau proteolysis. Thus, to investigate if proteasome inhibition leads to accumulation, hyperphosphorylation and aggregation of Tau, we used neuroblastoma cells overexpressing Tau proteins. Surprisingly, we showed that the inhibition of the proteasome led to a bidirectional degradation of Tau. Following this result, the cellular mechanisms that may degrade Tau were investigated. 相似文献
69.
70.
Friedman DB Hill S Keller JW Merchant NB Levy SE Coffey RJ Caprioli RM 《Proteomics》2004,4(3):793-811
Two-dimensional difference gel electrophoresis (2-D DIGE) coupled with mass spectrometry (MS) was used to investigate tumor-specific changes in the proteome of human colorectal cancers and adjacent normal mucosa. For each of six patients with different stages of colon cancer, Cy5-labeled proteins isolated from tumor tissue were combined with Cy3-labeled proteins isolated from neighboring normal mucosa and separated on the same 2-D gel along with a Cy2-labeled mixture of all 12 normal/tumor samples as an internal standard. Over 1500 protein spot-features were analyzed in each paired normal/tumor comparison, and using DIGE technology with the mixed-sample internal standard, statistically significant quantitative comparisons of each protein abundance change could be made across multiple samples simultaneously without interference due to gel-to-gel variation. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and tandem (TOF/TOF) MS provided sensitive and accurate mass spectral data for database interrogation, resulting in the identification of 52 unique proteins (including redundancies due to proteolysis and post-translationally modified isoforms) that were changing in abundance across the cohort. Without the benefit of the Cy2-labeled 12 sample mixture internal standard, 42 of these proteins would have been overlooked due to the large degree of variation inherent between normal and tumor samples. 相似文献