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Katsuobushi (dried bonito) flavor was prepared by vacuum ethanolic distillation (VED) without losing its original organoleptic characteristics. Gas chromatographic (GLC) profiles of the prepared Katsuobushi flavor were analyzed by calculating the pattern similarity coefficients and radian distances. The GLC profile of the phenolic fraction was the most similar to that of the whole flavor among the separated four fractions. The GLC profiles of Katsuobushi and Niboshi (dried sardine) mixtures blended at different ratios were compared, and the pattern similarity coefficients were found to be changed in proportion to the mixed ratios. These results show a good agreement with organoleptic evaluations and suggested that Katsuobushi flavor was ascribed to an integrated effect of many aroma compounds.  相似文献   

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Li BS  Wang XY  Ma FL  Jiang B  Song XX  Xu AG 《PloS one》2011,6(12):e28078

Background

High Resolution Melting Analysis (HRMA) is becoming the preferred method for mutation detection. However, its accuracy in the individual clinical diagnostic setting is variable. To assess the diagnostic accuracy of HRMA for human mutations in comparison to DNA sequencing in different routine clinical settings, we have conducted a meta-analysis of published reports.

Methodology/Principal Findings

Out of 195 publications obtained from the initial search criteria, thirty-four studies assessing the accuracy of HRMA were included in the meta-analysis. We found that HRMA was a highly sensitive test for detecting disease-associated mutations in humans. Overall, the summary sensitivity was 97.5% (95% confidence interval (CI): 96.8–98.5; I2 = 27.0%). Subgroup analysis showed even higher sensitivity for non-HR-1 instruments (sensitivity 98.7% (95%CI: 97.7–99.3; I2 = 0.0%)) and an eligible sample size subgroup (sensitivity 99.3% (95%CI: 98.1–99.8; I2 = 0.0%)). HRMA specificity showed considerable heterogeneity between studies. Sensitivity of the techniques was influenced by sample size and instrument type but by not sample source or dye type.

Conclusions/Significance

These findings show that HRMA is a highly sensitive, simple and low-cost test to detect human disease-associated mutations, especially for samples with mutations of low incidence. The burden on DNA sequencing could be significantly reduced by the implementation of HRMA, but it should be recognized that its sensitivity varies according to the number of samples with/without mutations, and positive results require DNA sequencing for confirmation.  相似文献   

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We are very pleased to announce a special issue,to be published in the spring of 2020,on"Single-cell Omics Analysis"in the journal Genomics,Proteomics&Bioinformatics(GPB).  相似文献   

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Three random translational -glucuronidase (gus) gene fusions were previously obtained in Arabidopsis thaliana, using Agrobacterium-mediated transfer of a gus coding sequence without promoter and ATG initiation site. These were analysed by IPCR amplification of the sequence upstream of gus and nucleotide sequence analysis. In one instance, the gus sequence was fused, in inverse orientation, to the nos promoter sequence of a truncated tandem T-DNA copy and translated from a spurious ATG in this sequence. In the second transgenic line, the gus gene was fused to A. thaliana DNA, 27 bp downstream an ATG. In this line, a large deletion occurred at the target site of the T-DNA. In the third line, gus is fused in frame to a plant DNA sequence after the eighth codon of an open reading frame encoding a protein of 619 amino acids. This protein has significant homology with animal and plant (receptor) serine/threonine protein kinases. The twelve subdomains essential for kinase activity are conserved. The presence of a potential signal peptide and a membrane-spanning domain suggests that it may be a receptor kinase. These data confirm that plant genes can be tagged as functional translational gene fusions.  相似文献   

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正We are very pleased to announce a special issue, to be published in the spring of 2020, on "Single-cell Omics Analysis" in the journal Genomics, Proteomics Bioinformatics(GPB). The cell has been primarily studied as a part of its bulk population for decades until recent  相似文献   

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正We are very pleased to announce a special issue, to be published in the spring of 2020, on‘‘Single-cell Omics Analysis’’ in the journal Genomics, ProteomicsBioinformatics (GPB).The cell has been primarily studied as a part of its bulk population for decades until recent breakthroughs in single-cell omics technologies. The study of the seemingly isogenic cellular populations often buries diverse cellular characteristics. Even in cells with the same cellular  相似文献   

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The two translocation chromosomes in the Poso 5B/7B translocation have been isolated in separate heterozygous aneuploid stocks (19II+5B+T). The translocation breakpoints are in the long arm of chromosome 7B and the short arm of chromosome 5B. The translocation chromosome bearing the 5BL pairing inhibitor was obtained as a homozygous aneuploid (19II+T 1 II ). The heterozygous aneuploid hemizygous for the pairing inhibitor (19II+5B+T2) was used to produce intergeneric hybrids. Only a small percentage were of the high-pairing type (17%), the majority having received chromosome 5B through the egg. This indicates a strong selection against eggs containing the translocation chromosome deficient for the pairing inhibitor.  相似文献   

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正We are very pleased to announce a special issue,to be published in the spring of 2020,on ‘‘Single-cell Omics Analysis’’ in the journal Genomics,ProteomicsBioinformatics (GPB).The cell has been primarily studied as a part of its bulk population for decades until recent  相似文献   

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Creationism is a religiously motivated worldview in denial of biological evolution that has been very resistant to change. We performed a textual analysis by examining creationist and pro-evolutionary texts for aspects of “experiential thinking”, a cognitive process different from scientific thought. We observed characteristics of experiential thinking as follows: testimonials (present in 100% of sampled creationist texts), such as quotations, were a major form of proof. Confirmation bias (100% of sampled texts) was represented by ignoring or dismissing information that would contradict the creationist hypothesis. Scientifically irrelevant or flawed information was re-interpreted as relevant for the falsification of evolution (75–90% of sampled texts). Evolutionary theory was associated to moral issues by demonizing scientists and linking evolutionary theory to atrocities (63–93% of sampled texts). Pro-evolutionary rebuttals of creationist claims also contained testimonials (93% of sampled texts) and referred to moral implications (80% of sampled texts) but displayed lower prevalences of stereotypical thinking (47% of sampled texts), confirmation bias (27% of sampled texts) and pseudodiagnostics (7% of sampled texts). The aspects of experiential thinking could also be interpreted as argumentative fallacies. Testimonials lead, for instance, to ad hominem and appeals to authorities. Confirmation bias and simplification of data give rise to hasty generalizations and false dilemmas. Moral issues lead to guilt by association and appeals to consequences. Experiential thinking and fallacies can contribute to false beliefs and the persistence of the claims. We propose that science educators would benefit from the systematic analysis of experiential thinking patterns and fallacies in creationist texts and pro-evolutionary rebuttals in order to concentrate on scientific misconceptions instead of the scientifically irrelevant aspects of the creationist—evolutionist debate.  相似文献   

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 We analyzed nucleotide and deduced amino acid sequence heterogeneity of sheep T-cell receptor β-chain cDNAs isolated from an anchored-polymerase chain reaction library. Evaluation of 34 individual rearrangements has defined 18 new β-chain variable region sequences which have been clustered into 13 families. Presumptive allelic polymorphisms of four of these variable regions have been defined, as well as ten distinct β-chain joining region sequences. The present analysis indicates that sheep T-cell receptor β-chains are composed of characteristic leader, variable, joining, and constant region sequences, and that imprecise joining and N-region addition contribute significantly to diversity in the third hypervariable region. Thus, it appears that sheep, like all other mammals studied to date, employ somatic rearrangement of multiple germline genes to create β-chain heterogeneity. These findings have allowed us to estimate the diversity of the sheep T-cell receptor β-chain variable region repertoire, and they provide information that will permit the evaluation of the role that specific T-cell populations play in naturally occurring and experimental diseases of sheep. Received: 20 October 1997 / Revised: 20 April 1998  相似文献   

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A combination of denaturing gradient gel electrophoresis (DGGE) and oligonucleotide probing was used to investigate the influence of soil pH on the compositions of natural populations of autotrophic β-subgroup proteobacterial ammonia oxidizers. PCR primers specific to this group were used to amplify 16S ribosomal DNA (rDNA) from soils maintained for 36 years at a range of pH values, and PCR products were analyzed by DGGE. Genus- and cluster-specific probes were designed to bind to sequences within the region amplified by these primers. A sequence specific to all β-subgroup ammonia oxidizers could not be identified, but probes specific for Nitrosospira clusters 1 to 4 and Nitrosomonas clusters 6 and 7 (J. R. Stephen, A. E. McCaig, Z. Smith, J. I. Prosser, and T. M. Embley, Appl. Environ. Microbiol. 62:4147–4154, 1996) were designed. Elution profiles of probes against target sequences and closely related nontarget sequences indicated a requirement for high-stringency hybridization conditions to distinguish between different clusters. DGGE banding patterns suggested the presence of Nitrosomonas cluster 6a and Nitrosospira clusters 2, 3, and 4 in all soil plots, but results were ambiguous because of overlapping banding patterns. Unambiguous band identification of the same clusters was achieved by combined DGGE and probing of blots with the cluster-specific radiolabelled probes. The relative intensities of hybridization signals provided information on the apparent selection of different Nitrosospira genotypes in samples of soil of different pHs. The signal from the Nitrosospira cluster 3 probe decreased significantly, relative to an internal control probe, with decreasing soil pH in the range of 6.6 to 3.9, while Nitrosospira cluster 2 hybridization signals increased with increasing soil acidity. Signals from Nitrosospira cluster 4 were greatest at pH 5.5, decreasing at lower and higher values, while Nitrosomonas cluster 6a signals did not vary significantly with pH. These findings are in agreement with a previous molecular study (J. R. Stephen, A. E. McCaig, Z. Smith, J. I. Prosser, and T. M. Embley, Appl. Environ. Microbiol 62:4147–4154, 1996) of the same sites, which demonstrated the presence of the same four clusters of ammonia oxidizers and indicated that selection might be occurring for clusters 2 and 3 at acid and neutral pHs, respectively. The two studies used different sets of PCR primers for amplification of 16S rDNA sequences from soil, and the similar findings suggest that PCR bias was unlikely to be a significant factor. The present study demonstrates the value of DGGE and probing for rapid analysis of natural soil communities of β-subgroup proteobacterial ammonia oxidizers, indicates significant pH-associated differences in Nitrosospira populations, and suggests that Nitrosospira cluster 2 may be of significance for ammonia-oxidizing activity in acid soils.Chemolithotrophic oxidation of ammonia to nitrate via nitrate (autotrophic nitrification) is of major importance in the global cycling of nitrogen in terrestrial, aquatic, and marine ecosystems (22). The first, and rate-determining, step of nitrification, ammonia oxidation, is carried out by the autotrophic ammonia-oxidizing bacteria, whose growth in liquid batch culture rarely occurs at pH values below 6.5. Nevertheless, autotrophic nitrification has been reported in acid soils at pH values as low as 3.5 (5). Nitrification in acid soils may be explained to some extent by growth on surfaces (2) or in aggregates (6), by ureolytic activity (1, 4), and by heterotrophic nitrifiers (14). An additional explanation is the existence of strains adapted to low-pH environments (7, 26), but although an acidophilic nitrite oxidizer has been isolated (9), acidophilic ammonia oxidizers have proved difficult to isolate in pure culture. Low growth rates, low biomass yield, and the limited number of distinguishing phenotypic characters for ammonia oxidizers have prevented the analysis of natural communities, in particular those in acid soils. The application of 16S ribosomal DNA (rDNA)-based techniques, however, enables the study of community structure in environmental samples, without the requirement for laboratory cultivation (8). Such studies have been particularly productive when applied to ammonia-oxidizing bacteria. With the exception of a small number of cultured marine strains belonging to the γ-proteobacteria, the phylogenetic analysis of rDNA sequences places all ammonia oxidizers in a monophyletic group within the β-proteobacteria. This group consists of two distinct monophyletic genera, Nitrosomonas and Nitrosospira (10, 28, 30, 31). An analysis of natural ammonia oxidizer populations from a variety of environments has revealed further subdivision (26), based on phylogenetic analysis of a 300-bp fragment of the 16S rDNA molecule spanning the V2 and V3 regions (20). An analysis of 1.1-kb regions (incorporating this 300-bp fragment) of representative environmental sequences has shown that Nitrosospira can be further subdivided into at least four clusters, designated 1 to 4 (26). The Nitrosomonas genus may also be subdivided, and Stephen et al. (26) recognized three clusters within this genus, designated 5 to 7 (Fig. (Fig.1).1). Of particular relevance to this study is a cluster containing three soil clones, here referred to as cluster 6a. These and other studies (11, 15) indicate that sequences from members of the genus Nitrosospira were more abundant than Nitrosomonas in a range of environments and suggest that the available pure cultures represent only a limited selection of the phylogenetic and, by inference, physiological diversity of natural ammonia oxidizer populations. These studies are based on the hypothesis that environmental sequences falling within the Nitrosomonas and Nitrosospira clades originate from autotrophic ammonia oxidizers (26). Evidence for this hypothesis is based on their phylogenetic positions relative to cultured taxa which uniformly possess this phenotype, including recently isolated cultures of Nitrosospira (28). In addition, no sequence from a nonautotrophic ammonia oxidizer falls within this clade. Open in a separate windowFIG. 1Schematic tree of the β-subgroup ammonia-oxidizing bacteria based on 303 bp of 16S rDNA sequence spanning E. coli positions 198 to 500 (3) and target groups for probes described in Table Table1.1. Ambiguous sites were removed by using the GDE 2.2 “mask” function (16) before transfer of the data to the ARB sequence analysis program (25). The tree was generated by neighbor joining (24) with the Jukes and Cantor (13) correction in ARB. Clusters of sequences are scaled vertically to represent the number of sequences and horizontally to represent the extent of variation within each cluster. Cluster designations are as described in Stephen et al. (26) with the exception of cluster 6a, which contains three soil clones (see text), and cluster 6b, which contains the remainder of cluster 6 sequences previously described (26). Soil clone pH4.2/28 and marine enrichment sequence AEM3 cannot be placed unequivocally in this scheme. The scale bar represents 0.1 estimated changes per nucleotide position. Sequence data were compiled from references 10, 15, 17, 21, 26, and 28).The available 16S rDNA sequence data for β-subgroup ammonia oxidizers can be interpreted to suggest that particular phylogenetic clusters may be associated with specific habitats (26). For example, sequences from Nitrosospira cluster 2 and Nitrosospira cluster 3 were apparently more common in acid and neutral agricultural soils, respectively (26), while sequences from Nitrosomonas cluster 6 and Nitrosospira cluster 4 were detected at similar frequencies in both soils. Biogeographic or temporal studies of community structure by determination of sequence abundance in gene libraries are severely limited by the time required for sequence acquisition and analysis, and the approach is not necessarily quantitative. Denaturing gradient gel electrophoresis (DGGE) provides a complementary tool for the analysis of complex microbial communities (19, 25). It involves the separation of DNA fragments of identical length on the basis of differences in denaturant sensitivity in an acrylamide gel matrix, resulting from differences in the primary sequence. PCR products generated from different samples can thereby be compared directly, based on their mobility, without the need for cloning or DNA sequence analysis. Specific amplification and DGGE analysis of 16S rDNA for β-subgroup ammonia-oxidizing bacteria successfully demonstrated differences between communities in dune soil samples (15). However, differences in mobility between the various sequence clusters and overlapping banding patterns prevented precise identification of the community members, which necessitated band excision and sequence determination.The recent expansion of the 16S rDNA sequence database for β-subgroup ammonia oxidizers provides the potential for the design of improved oligonucleotide probes for the analysis of natural populations (10, 15, 21, 26, 28). Published β-subgroup ammonia oxidizer probes have been based on sequence information from a limited number of cultured organisms (11, 12, 29) and would not detect much of the diversity determined by Stephen et al. (26), restricting their value for the analysis of natural communities.The first aim of this study was to design and test oligonucleotide probes capable of distinguishing the subgroups within the different clusters of β-subgroup ammonia oxidizers from each other. The second aim was then to use these probes to identify bands separated by DGGE analysis of PCR products generated from soil with ammonia oxidizer-specific primers. In particular, we aimed to investigate further the hypotheses (26) that Nitrosospira may be of significance for ammonia oxidation in acid soils and that the relative abundances of different sequence clusters are related to soil pH.  相似文献   

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The expansion of agriculture and aquaculture farms in the coastal areas has led to conversion of mangroves in the recent past. The extent of mangroves has also changed due to the erosion of mangroves along the coast and accretion near river mouths, leading to the formation of new mangrove areas. This study has been undertaken in the mangroves of the Godavari estuary, Andhra Pradesh, India to understand the changes in the extent of mangroves, namely accreted mangroves, erosion due to wave action and river water flow during floods, and changes due to forest restoration between 1986 and 2001, through remote sensing. The geomorphological changes due to river water flow in and around the mangroves have also been analysed. The changes in the vegetation due to forest restoration and natural regeneration are appreciable, while the changes in the area due to erosion and accretion are more or less equal. An analysis of the remote sensing images of 1986 and 2001 reveal that the mangroves outside the forest boundary have been converted to aquaculture. The sand spit of Hope Island has changed with time and has grown nearly 2.6 km between 1937 and 2001.  相似文献   

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Summary A Sequential Injection Analysis (SIA) system for monitoring -amylase activity is described. The SIA analyser is a further development of previously investigated Flow Injection Analysis (FIA) analyser. The analysis of -amylase activity is based on monitoring the decoloration of an iodine-starch complex. Performances of the SIA analyser have been compared with the FIA analyser. A good agreement has been obtained between the SIA measurements and the FIA measurements.  相似文献   

20.
A molecular model of ionic channel formed by flexible molecules of amphotericin B and cholesterol is proposed. Complexes with axial symmetry from 5 to 11 were simulated. In contrast to the model of the channel formed from rigid molecules, flexible molecules form a tightly packed structure consolidated by both dispersive forces and intermolecular hydrogen bonds. Contributions of a lactone ring, polar heads, cholesterol and lipid environments to the global energy of the complex formation are discussed. Among the complexes capable of ionic transport, that of axial symmetry eight is preferable. Two types of complexes, differing by the number of intramolecular hydrogen bonds, are shown to be possible. Received: 25 April 1997/Revised: 20 November 1997  相似文献   

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