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At least 631 records · Page 35Linked to original sources
PubMed2006

Discovery of regulatory molecular events and biomarkers using 2D capillary chromatography and mass spectrometry.

An important component of proteomic research is the high-throughput discovery of novel proteins and protein-protein interactions that control molecular events that contribute to critical cellular functions and human disease. The interactions of proteins are essential for cellular functions. Identifying perturbation of normal cellular protein interactions is vital for understanding the disease process and intervening to control the disease. A second area of proteomics research is the discovery of proteins that will serve as biomarkers for the early detection, diagnosis and drug treatment response for specific diseases. These studies have been referred to as clinical proteomics. To discover biomarkers, proteomics research employs the quantitative comparison of peptide and protein expression in body fluids and tissues from diseased individuals (case) versus normal individuals (control). Methods that couple 2D capillary liquid chromatography (LC) and tandem mass spectrometry (MS/MS) analysis have greatly facilitated this discovery science. Coupling 2D-LC/MS/MS analysis with automated genome-assisted spectra interpretation allows a direct, high-throughput and high-sensitivity identification of thousands of individual proteins from complex biological samples. The systematic comparison of experimental conditions and controls allows protein function or disease states to be modeled. This review discusses the different purification and quantification strategies that have been developed and used in combination with 2D-LC/MS/MS and computational analysis to examine regulatory protein networks and clinical samples.

Biomarkers↗
PubMed1988

Histologic reporting of malignant melanoma.

The schema for histologic reporting of malignant melanoma outlined above is incomplete. A number of variables, including quantification of tumor cell pigmentation, description of solar degeneration in surrounding stroma, and extent of S-100 protein immunoreactivity by tumor cells, have not been addressed. In addition, it is likely that within the next several years, additional parameters, including those identified by the use of in situ genomic probes (Chapter 3), will become known to confer prognostic information when assessed histologically in biopsy material. Nonetheless, this approach represents a start, an attempt to achieve uniformity in histologic reporting of melanoma. It represents a three-tiered approach. First is the establishment of a malignant melanocytic lesion (malignant melanoma) and the assessment of the anatomic level and extent of invasion of the dermis, which correlates directly with metastatic potential (the vertical growth phase measured in millimeters). Subclassification of the radial growth phase is optional and, by convention, is also reported in this "above the line" portion of the diagnostic assessment. Second, a number of subsidiary diagnostic statements, usually in the form of notes or comments, are recommended. These include assessment of overlying epidermal ulceration, a description of the morphology and mitotic activity of the vertical growth phase nodule, an assessment of the presence or absence of vascular invasion and microscopic satellite formation, a description of the host mononuclear cell response and/or regression, and mention of associated pathology. Finally, an additional narrative statement may be included to describe such things as extent of S-100 immunoreactivity or to modify in a more descriptive manner the database provided above. Although this last category is neither crucial nor mandatory, it serves to add to a collective database from which future determinations concerning the prognostic significance of new histologic parameters may be formulated. Table 6.3 provides a sample report based on the above considerations. This method of histologic reporting is recommended because it includes important diagnostic information as well as parameters for prognosis. Although certain details of less impelling current significance are included, these are of potential future importance as a greater number of patients with malignant melanoma are followed prospectively for prolonged periods of time. These factors may also prove to be significant in the accumulation of a database for research.

Epidermis↗
PubMed1996

Establishment and serial quantification of intrahepatic xenografts of human hepatocellular carcinoma in severe combined immunodeficiency mice, and development of therapeutic strategies to overcome multidrug resistance.

A murine model in which to study multiple drug resistance in human hepatocellular carcinoma was developed. PRF/PLC/5 hepatoma cells (Alex 0) and an induced multidrug resistant clone (Alex 0.5) were injected intrasplenically into severe combined immunodeficiency mice. In 70% of injected mice, hepatoma cells engrafted in the liver and grew as intrahepatic metastasis. Since Alex cells contain an integrated hepatitis B virus genome and secrete hepatitis B surface antigen (HBsAg), the serum HBsAg concentration in tumor-bearing mice was used to quantitate tumor burden. Tumor wet weight determined at necropsy was directly proportional to the serum HBsAg concentration. In Alex 0 cells, IC50s for doxorubicin, vinblastine, and cis-platinum were 0.35 microM, 0.029 microM, and 3.70 microM, respectively. Alex 0.5 cells were 25-, 14-, and 1.4-fold more resistant to doxorubicin, vinblastine, and cis-platinum, respectively. Immunoblotting of Alex 0 cell membranes with an anti-P-glycoprotein antibody (C219) revealed small amounts of P-glycoprotein, whereas Alex 0.5 membranes overexpressed the protein. Concurrent exposure to verapamil (10 microM) sensitized both cell lines to the cytotoxic action of vinblastine and doxorubicin but had no effect on the cytotoxicity of cis-platinum. Mice bearing intrahepatic xenografts derived from Alex 0 and 0.5 cells had no response to treatment with i.v. vinblastine or doxorubicin, as was anticipated from in vitro drug testing. Addition of verapamil to vinblastine treatment did not improve the success of in vivo chemotherapy. Immunotherapy with a human anti-P-glycoprotein antibody (MRK16) suppressed the in vivo growth of tumors derived from both cell lines. The effect was most pronounced in mice bearing Alex 0.5 tumors. Immunoblotting of tumors which initially responded to MRK16 therapy, but subsequently relapsed, revealed a marked decrease in P-glycoprotein expression when compared to results in tumors that were untreated or treated with vinblastine or control antibody. In summary, we have developed an intrahepatic tumor xenograft model of human hepatocellular carcinoma in mice that permits noninvasive serial quantification of tumor burden by determination of serum HBsAg levels and demonstrated a positive response to immunotherapy with anti-P-glycoprotein antibodies.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

AIDS in an HIV-seronegative Ghanaian woman with intersubtype A/G recombinant HIV-1 infection.

A 29-year-old Ghanaian woman who developed AIDS while being HIV-antibody seronegative was investigated during a collaborative study aimed at the identification of viral causes of a HIV-seronegative AIDS syndrome in West Africa. Plasma was screened with a panel of EIA tests for antibodies to HIV and HIV-1 p24 antigen. Retroviral infection was investigated by detection of reverse transcriptase (RT) activity in plasma, viral RNA amplification and quantification, and virus isolation. Positive amplification products were sequenced and phylogenetic analyses were carried out. Most EIA tests were unable to demonstrate the presence of anti-HIV anti-bodies, whereas confirmatory assays yielded inconclusive results. Retroviral infection was documented by detection of RT activity, HIV-1-specific genomic amplification and virus isolation. This virus was HIV-1 subtype A with an unusual six amino acid insertion in the gp120 V4 loop and with the nef gene of subtype G. The patient's plasma did not react with either autologous or heterologous viral lysates or HIV-1 peptides, whereas antibodies to other viral antigens were present. In conclusion, the Ghanaian patient exhibited a rare subtype A/G recombinant HIV-1 infection with a near absence of a HIV-specific humoral response. The lack of detectable antibody response might be due to either a highly pathogenic, rapidly fatal, HIV-1 infection preventing the development of the typical humoral immune response or to a host-related dysfunction of the immune system. Direct antigenemia or genomic detection of the virus should be undertaken when clinical or biological data suggests an HIV infection in the absence of serological evidence.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Concordance between enzyme activity and genotype of glutathione S-transferase theta (GSTT1).

Blood samples from 140 healthy German volunteers were used to further characterize the genetic polymorphism of the human theta class glutathione S-transferase 1 (GSTT1). For measurements of GSTT1 activity, hemolysates were incubated in vitro with different concentrations of dichloromethane. The resulting enzymatically mediated production of formaldehyde was determined colorimetrically by the Nash reaction. GSTT1 genotyping was performed by polymerase chain reaction (PCR) methods using genomic DNA from total white blood cells. The prevalence of homozygous deletion of the GSTT1 gene was 19.3% (95% confidence limits: 12.2-27.7%). There was a high agreement between genotyping and phenotyping data. The individuals with the null genotype had a rate of formaldehyde production below the limit of quantification. In addition, in the group of GSTT1-positive individuals, we could differentiate highly active people (35.7%) from individuals with an intermediate enzyme activity (45.0%). It can be concluded that the PCR method is suitable to quickly genotype large populations, whereas the phenotyping assay at present offers the advantage of differentiating heterozygously from homozygously active subjects. Our results confirm the ethnic differences in the prevalence of the homozygous deleted genotype which were previously observed and seem to exist even between closely related ethnic groups such as German and Swedish populations.

Female↗
PubMed2002

Extrachromosomal genes: a powerful tool in gene targeting approaches.

Several studies, some of which have been updated during the recent workshop entitled Genome Medicine: Gene Therapy for the Millennium (Rome, 30 September-3 October 2001), have highlighted the usefulness of extrachromosomal or episomal genes in gene targeting strategies. Due to the selectable nature of antibiotic resistance and reporter genes, targeted correction of mutated versions of these extrachromosomal genes allows an accurate quantification of correction frequency. In addition, these model systems facilitate and speed up the optimization of critical parameters for the successful application of gene targeting approaches. In fact, type of cell line, gene delivery system, molar ratio of episomal target/therapeutic constructs, nature and design of therapeutic complexes and different recombinative proteins may be critical for the actual feasibility of each method. Although virus-based approaches are now being investigated as well, this article is focusing on the targeted correction of extrachromosomal genes by the use of small DNA fragments (SDF), chimeric RNA/DNA oligonucleotides (RDO) and triplex-forming oligonucleotides (TFO).

DNA Fragmentation↗
PubMed2002

Analysis of differential gene expression by ligation specificity-based transcript profiling.

An open architecture mRNA profiling technology, LEAD (Ligation specificity-based Expression Analysis Display), was developed for studying differential gene expression. This method utilizes restriction enzymes with N(m) degeneracy in their recognition/cleavage sequences to fractionate cDNA population (N represents any one of the four possible bases; while m > or = 1, represents the number of degenerate bases). The fractionated cDNAs are subpooled by selective ligation with specific adapters, and then amplified and labeled by PCR. Fluorescent-labeled cDNA fingerprints are separated by electrophoresis as distinct bands with unique size and sequence, and quantified electronically by using the LEAD Finder program. The specificity of ligation and the uniform efficiency of PCR reaction allow precise quantification of differential gene expression among samples. Transcripts of low abundance (1/100,000 copies) can be detected, allowing the status of nearly all mRNA to be monitored. Because of its sequence independence, this technology can be used to monitor gene expression in both model and nonmodel systems lacking whole genome information. It can also be applied to separate and collect different cDNA species fingerprints to build a nonredundant EST library for microarray and other applications.

Animals↗
PubMed2006

Differentially active origins of DNA replication in tumor versus normal cells.

Previously, a degenerate 36 bp human consensus sequence was identified as a determinant of autonomous replication in eukaryotic cells. Random mutagenesis analyses further identified an internal 20 bp of the 36 bp consensus sequence as sufficient for acting as a core origin element. Here, we have located six versions of the 20 bp consensus sequence (20mer) on human chromosome 19q13 over a region spanning approximately 211 kb and tested them for ectopic and in situ replication activity by transient episomal replication assays and nascent DNA strand abundance analyses, respectively. The six versions of the 20mer alone were capable of supporting autonomous replication of their respective plasmids, unlike random genomic sequence of the same length. Furthermore, comparative analyses of the endogenous replication activity of these 20mers at their respective chromosomal sites, in five tumor/transformed and two normal cell lines, done by in situ chromosomal DNA replication assays, involving preparation of nascent DNA by the lambda exonuclease method and quantification by real-time PCR, showed that these sites coincided with chromosomal origins of DNA replication in all cell lines. Moreover, a 2- to 3-fold higher origin activity in the tumor/transformed cells by comparison to the normal cells was observed, suggesting a higher activation of these origins in tumor/transformed cell lines.

Base Sequence↗
PubMed2002

Development of a diagnostic one-tube RT-PCR for the detection of Rift Valley fever virus.

Diagnosis of Rift Valley fever (RVF) is based on serology and virus isolation. The disadvantages of the former include poor sensitivity, high cost, risks associated with using infectious virus as antigen, the lengthy duration of ELISA as well as cross-reactivity with other Phleboviruses. We developed, optimised and evaluated a one-tube reverse-transcription-polymerase chain reaction (RT-PCR) for the detection of Rift Valley fever virus (RVFV) in ruminants. The PCR primers for this assay were designed to anneal to a region within the M segment of the virus genome, encoding glycoproteins G1 and G2. A PCR amplicon of 363 bp was obtained. The sensitivity of the assay was determined to be 0.25 TCID50. This test should allow for the early and rapid detection of RVFV in both serum and whole blood. In addition, it could facilitate the quantification of antigen for the manufacture of current vaccines.

Animals↗
PubMed2003

Current insights into the pathogenesis, diagnosis and therapy of inflammatory cardiomyopathy.

Persistence of cardiotropic viruses (enterovirus, adenovirus) and anticardiac autoimmunity constitute the predominant etiopathogenic pathways of dilated cardiomyopathy (DCM). The diagnosis of inflammatory cardiomyopathy (InfCM) imposes sensitivity and specificity requirements, which are not fulfilled by the histological Dallas Criteria. The immunohistological quantification and characterization of immunocompetent infiltrates and cell adhesion molecule (CAM) expression has endorsed a new entity of secondary cardiomyopathies acknowledged by the World Health Organization (WHO), InfCM, in approximately 50% of DCM patients. In the absence of viral persistence, InfCM patients benefit from immunosuppressive treatment. Enteroviral and adenoviral genomes have been detected in a significant proportion of DCM patients. Enteroviral persistence is associated with an adverse prognosis. The induction of the coxsackie-adenovirus receptor (CAR) exclusively in 63% of DCM patients, but not in other cardiomyopathies, might constitute a key molecular determinant for cardiotropic viral infections in DCM. In InfCM patients with enterovirus or adenoviral persistence, interferon-beta administration leads to viral elimination and cessation of the intramyocardial inflammation, paralleled by a significant improvement of left ventricular systolic function and heart failure symptoms. The biopsy-guided etiopathogenic differentiation of DCM has endorsed specific treatment strategies: immunosuppressive regimens are favorable in autoimmune InfCM, whereas patients with viral persistence benefit from antiviral immunomodulation.

Cardiomyopathy, Dilated↗
PubMed2026

Pan-Cancer Quantification of Driver Alteration Transmission Across Molecular Layers Reveals Limited Propagation to Protein Abundance.

Precision oncology relies primarily on DNA-level alterations for therapeutic decisions, but the extent to which driver mutations propagate to protein abundance has not been systematically evaluated. Here, I developed a regression-based transmission score (TS_R 2) to quantify driver alteration signal propagation across DNA, mRNA, and protein layers. Applying this framework to matched genomic, transcriptomic, proteomic, and phosphoproteomic data from 754 Clinical Proteomic Tumor Analysis Consortium (CPTAC) tumors across seven cancer types, I analyzed 86 driver gene-cancer type pairs, of which 83 were evaluable for the full two-layer transmission score. I employed covariate-adjusted regression for each molecular transition, assessing significance via permutation testing (n = 1000). Mixed-effects modeling then partitioned gene-intrinsic from cancer-type-dependent effects. Only 5 of 83 evaluable pairs (6%) demonstrated high transmission (TS_R 2 > 0.05), with receptor tyrosine kinases (EGFR, FGFR2) exemplifying this class. The primary bottleneck occurred at the mutation-mRNA transition, not mRNA-protein translation. Gene identity accounted for 49% of transmission efficiency variance, nearly double the contribution of cancer type (29%). Copy number alterations transmitted signals 13.8-fold more efficiently than point mutations, and truncating mutations showed higher transmission than missense variants (Wilcoxon p = 0.005). Microsatellite instability attenuated mRNA-protein transmission in UCEC and COAD. These findings demonstrate that many driver alterations show limited propagation to protein abundance. This challenges DNA-only interpretations in precision oncology and provides a framework for integrated functional driver prioritization.

Humans↗
PubMed2002

Quantification of human mitochondrial DNA in a real time PCR.

Recently, a moderately priced machine for real-time quantitative PCR has become available, the Perkin Elmer 5700. The rapid and quantitative assay of mitochondrial DNA (mtDNA) copy number is potentially useful in a variety of molecular, evolutionary and forensic fields. Using this new tool, we have evaluated the precision and reliability of the real time PCR to quantify undeleted mitochondrial genome copy number, and to determine the frequency of an age-associated deletion of 4977 base pairs in length, in 42 human iliopsoas muscle DNA samples from persons of known age. We have evaluated the accuracy with which age can be predicted, knowing only the frequency of this common 4977 bp deletion, and derived a statistical formula which describes the confidence with which the 4977 bp frequency predicts age. The results indicate that the mutation frequency could be used to distinguish between tissue from young and old individuals. However in this data set, while there was considerable agreement of 4977 bp frequency among replicates from the same individual sample, there was substantial diversity of mean mutation frequency between individuals of the same or similar ages. The simplest interpretation of these results is that there are biological modifiers of 4977 bp frequency that are age-independent, which are potentially interesting but may limit the usefulness of this deletion frequency alone as a "molecular forensic clock."

Autopsy↗
PubMed2004

Some aspects of the physiological role of ion channels in the nervous system.

Recent analyses of the genomes of several animal species, including man, have revealed that a large number of ion channels are present in the nervous system. Our understanding of the physiological role of these channels in the nervous system has followed the evolution of biophysical techniques during the last century. The observation and the quantification of the electrical events associated with the operation of the ionic channels has been, and still is, one of the best tools to analyse the various aspects of their contribution to nerve function. For this reason, we have chosen to use electrophysiological recordings to illustrate some of the main functions of these channels. The properties and the roles of Na+ and K+ channels in neuronal resting and action potentials are illustrated in the case of the giant axons of the squid and the cockroach. The nature and role of the calcium currents in the bursting behaviour of the neurons are illustrated for Aplysia giant neurons. The relationship between presynaptic calcium currents and synaptic transmission is shown for the squid giant synapse. The involvement of calcium channels in survival and neurite outgrowth of cultured neurons is exemplified using embryonic cockroach brain neurons. This same neuronal preparation is used to illustrate ion channel noise and single-channel events associated with the binding of agonists to nicotinic receptors. Some features of the synaptic activity in the central nervous system are shown, with examples from the cercal nerve giant-axon preparation of the cockroach. The interplay of different ion conductances involved in the oscillatory behaviour of the Xenopus spinal motoneurons is illustrated and discussed. The last part of this review deals with ionic homeostasis in the brain and the function of glial cells, with examples from Necturus and squids.

Animals↗
PubMed2005

Upregulation of the BRCA1 gene in human germ cells and in preimplantation embryos.

The quantification of BRCA1 messenger RNA molecules by a quantitative competitive one-step reverse transcriptase polymerase chain reaction method indicates that BRCA1 is upregulated both in human male and female germ cells and in preimplantation embryos. Because BRCA1 is involved in several pathways that participate in preserving intact chromosome and genome integrity, these data suggest that BRCA1 dysfunction might alter human embryogenesis or fertility.

Blastocyst↗
PubMed1994

Outcome prediction in childhood acute lymphoblastic leukaemia by molecular quantification of residual disease at the end of induction.

Methods to detect and quantify minimal residual disease (MRD) after chemotherapy for acute lymphoblastic leukaemia (ALL) could improve treatment by identifying patients who need more or less intensive therapy. We have used a clone-specific polymerase chain reaction to detect rearranged immunoglobulin heavy-chain gene from the leukaemic clone, and quantified the clone by limiting dilution analysis. MRD was successfully quantified, by extracting DNA from marrow slides, from 88 of 181 children with ALL, who had total leucocyte counts below 100 x 10(9)/L at presentation and were enrolled in two clinical trials, in 1980-84 and 1985-89. Leukaemia was detected in the first remission marrow of 38 patients, in amounts between 6.7 x 10(-2) and 9.9 x 10(-7) cells; 26 of these patients relapsed. Of 50 patients with no MRD detected, despite study of 522-496,000 genomes, only 6 relapsed. The association between MRD detection and outcome was significant for patients in each trial. In the first trial, patients relapsed at all levels of detected MRD, whereas in the later trial, in which treatment was more intensive and results were better, the extent of MRD was closely related to the probability of relapse (5 of 5 patients with > 10(-3) MRD, 4 of 10 with 10(-3) to 2 x 10(-5), 0 of 3 with levels below 2 x 10(-5), and 2 of 26 with no MRD detected). Early quantification of leukaemic cells after chemotherapy may be a successful strategy for predicting outcome and hence individualizing treatment in childhood ALL, because the results indicate both in-vivo drug sensitivity of the leukaemia and the number of leukaemic cells that remain to be killed by post-induction therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Rapid and precise quantification of HIV-1 RNA in plasma using a branched DNA signal amplification assay.

The level of human immunodeficiency virus type 1 (HIV-1) RNA in human plasma has been quantitated directly with use of a solid-phase nucleic acid hybridization assay, based on branched DNA (bDNA) signal amplification technology with chemiluminescent detection. Signal amplification is accomplished by the incorporation of sites for 1,755 alkaline phosphatase-labeled probes per genome of HIV-1, after successive hybridization of target-specific oligonucleotides and bDNA amplifier molecules. The assay is performed in microwells, much like an immunoassay, and is amenable to routine laboratory use. Reproducibility and specificity studies indicated that the bDNA method was precise and showed no reactivity with seronegative donors. HIV-1 RNA levels were quantitated for 348 seropositive specimens, with a detection rate of 83% for those specimens from patients with < 500 CD4+ T-cell counts. Plasma RNA levels were found to change with disease stage, and in response to antiviral therapy. Quantitation of HIV-1 RNA in the plasma of HIV-1-infected patients, with use of the bDNA assay, may be a useful method for monitoring HIV-1 disease progression and therapeutic response.

Acyclovir↗
PubMed2006

Evaluation of ZAP-70 expression by flow cytometry in chronic lymphocytic leukemia: A multicentric international harmonization process.

The clinical course of patients with chronic lymphocytic leukemia (CLL) is heterogeneous with some patients requiring early therapy whereas others will not be treated for years. The evaluation of an individual CLL patient's prognosis remains a problematic issue. The presence or absence of somatic mutations in the IgVH genes is currently the gold-standard prognostic factor, but this technique is labor intensive and costly. Genomic studies uncovered that 70 kDa zeta-associated protein (ZAP-70) expression was associated with unmutated IgVH genes and ZAP-70 protein expression was proposed as a surrogate for somatic mutational status. Among the available techniques for ZAP-70 detection, flow cytometry is most preferable as it allows the simultaneous quantification of ZAP-70 protein expression levels in CLL cells and residual normal lymphocyte subsets. However, several factors introduce variability in the results reported from different laboratories; these factors include the anti-ZAP-70 antibody clone and conjugate, the staining procedure, the gating strategy, and the method of reporting the results. The need for standardization of the approach led to the organization of an international working group focused on harmonizing all aspects of the technique. During this workshop, a technical consensus was reached on the methods for cell permeabilization and immunophenotyping procedures. An assay was then designed that allowed comparison of two clones of anti-ZAP-70 antibody and the identification of the expression of this molecule in B, T, and NK cells identified in a four multicolor analysis. This procedure was applied to three stabilized blood samples, provided by the UK NEQAS group to all participating members of this study, in order to minimize variability caused by sample storage and shipment. Analysis was performed in 20 laboratories providing interpretable data from 14 centers. Various gating strategies were used and the ZAP-70 levels were expressed as percentage positive (POS) relative to isotype control or normal B-cells or normal T-cells; in addition the levels were reported as a ratio of expression in CLL cells relative to T-cells. The reported level of ZAP-70 expression varied greatly depending on the antibody and the method used to express the results. The CLL/T-cell ZAP-70 expression ratio showed a much lower interlaboratory variation than other reporting strategies and is recommended for multicenter studies. Stabilization results in decreased expression of CD19 making gating more difficult and therefore stabilized samples are not optimal for multicentric analysis of ZAP-70 expression. We assessed the variation of ZAP-70 expression levels in fresh cells according to storage time, which demonstrated that ZAP-70 is labile but sufficiently stable to allow comparison using fresh samples distributed between labs in Europe. These studies have demonstrated progress toward a consensus reporting procedure, and further work is underway to harmonize the preparation and analysis procedures.

Antibodies, Monoclonal↗
PubMed1998

Bacterial transcript imaging by hybridization of total RNA to oligonucleotide arrays.

We have used high-density oligonucleotide probe arrays (chips) for bacterial transcript imaging. We designed a chip containing probes representing 106 Hemophilus influenzae genes and 100 Streptococcus pneumoniae genes. The apparent lack of polyadenylated transcripts excludes enrichment of mRNA by affinity purification and we thus used total, chemically biotinylated RNA as hybridization probe. We show that hybridization of Streptococcus RNA to a chip allows simultaneous quantification of the transcript levels. The sensitivity was found to be in the range of one to five transcripts per cell. The quantitative chip results were in good agreement with conventional Northern blot analysis of selected genes. This technology allows simultaneous and quantitative measurement of the transcriptional activity of entire bacterial genomes on a single oligonucleotide probe array.

Biotinylation↗