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N Blin

Publications and source records attributed to N Blin.

At least 127 records · Page 7Linked to original sources
PubMed1989

Interspecies relationship of a repetitive chromosome-specific DNA.

A repetitive DNA motif, consisting of 48 bp units (D22Z3) was shown to reside in the pericentric region of the human chromosome 22. In genomic blots it was displaying cross-homology only to great ape species, the restriction patterns being similar but specific for each species investigated. Non-radioactive in situ hybridization revealed a minor homology to human chromosomes 14/15 when less stringent conditions were applied. In gorilla, only chromosomes corresponding to human G-group autosomes showed a distinct cross-hybridization, whereas in chimpanzee, homology to this sequence was observed for all acrocentric chromosomes, even with reduced signal accumulation for the human 22 equivalent at higher stringencies.

Animals↗
PubMed1989

[Tumor-specific changes in the mitochondrial genome of oncocytomas].

Two astrocytomas, 5 colon carcinomas, 3 clear cell carcinomas of kidney, 5 renal oncocytomas and 1 oxyphile adenoma of thyroid were examined for mitochondrial DNA-alterations applying 5 different restriction enzymes (Alu I, Hae III, Hpa II, Rsa I, Hinf I). Only by applying Hinf I restriction enzyme digestion we were able to prove alterations of the mitochondrial DNA in oncocytomas (2 additional bands of about 55 or 35 base pairs). This was the first proof of mitochondrial DNA-alteration in a human tumor. The present sequence analyses of DNA-alteration will help to explain which importance is attached to the alterations regarding genesis of oncocytic tumors.

Adenoma↗
PubMed1989

Renal oncocytoma. A phenotypic and genotypic entity of renal parenchymal tumors.

The light and electron microscopic morphology of two renal parenchymal tumors was consistent with the diagnosis of renal oncocytoma. Both tumors had a mosaic chromosome pattern of cells with normal and abnormal karyotypes. No recurrent chromosome aberration and also no rearrangement of chromosome 3p was found. Restriction analysis of the mitochondrial DNA revealed a new autoradiographic band at about 50 basepairs in size occurring exclusively in oncocytomas. The possible use of these findings in the diagnosis of renal oncocytomas is discussed.

Adenoma↗
PubMed1988

Human KRAS oncogene expression in meningioma.

Expression of 16 oncogenes was investigated in a series of human meningiomas showing a normal chromosome complement or the characteristic monosomy 22 but no structural aberrations detectable by banding analysis. By dot hybridization, the only expressed sequence detected was KRAS. The expression was elevated approximately 6--8-fold in comparison to matrix tissue (meninges) and to fibroblasts of the corresponding patient. Northern blot analysis displayed the typical banding pattern and an 8--10-fold overexpression. DNA analysis did not reveal gene amplification or major rearrangements in the KRAS gene structure.

Blotting, Northern↗
PubMed1988

A human glioblastoma line with karyotypic nullisomy 13 containing several chromosome 13-specific sequences.

Using a biochemical approach (evaluation of esterase D activity) and recombinant DNA techniques (in situ and filter hybridization with specific DNA probes) a glioblastoma cell line with karyotypical nullisomy 13 was shown to contain several chromosome #13-specific sequences. They were assigned to a marker chromosome. This finding suggests that cytogenetic descriptions of deletions or chromosome losses will gain considerable power of the statement when supplemented by molecular analysis, particularly since, by now, DNA probes have been accumulated for all chromosomes and all their subfragments.

Chromosome Banding↗
PubMed1988

A novel centromeric repetitive DNA from human chromosome 22.

A recombinant DNA clone localized in the centromeric region of chromosome 22 was isolated from a flow-sorted human chromosome 22 DNA library. When the original insert of about 1.9 kb was used to probe Southern blots of EcoRI-digested genomic DNA it revealed at least 40 fragments. A comparable pattern was obtained with each of the three subclones (800, 700, and 380 bp). In situ hybridization showed signals clustered in the region 22cen. DNA sequence analysis using the 380 bp fragment subcloned in pTZ18/19 (p22hom48.4) revealed eight copies of a 48 bp repeat and the size of hybridizing restriction fragments indicated that this tandemly repeated sequence is spread over a region of a few hundred kilobases. Whereas this novel DNA, termed D22Z3, displayed no sequence homology to rodent and monkey genomes cross-homology was discernible for DNA from two great ape species.

Animals↗
PubMed1988

Rapid step-gradient purification of mitochondrial DNA.

A convenient modification of the step gradient (CsCl/ethidium bomide) procedure is described. This rapid method allows isolation of covalently closed circular DNA separated from contaminating proteins, RNA and chromosomal DNA in ca. 5 h. Large scale preparations can be performed for circular DNA from eukaryotic organelles (mitochondria). The protocol uses organelle pelleting/NaCl-sarcosyl incubation steps for mitochondria followed by a CsCl step gradient and exhibits yields equal to the conventional procedures. It results in DNA sufficiently pure to be used for restriction endonuclease analysis, subcloning, 5'-end labeling, gel retention assays, and various types of hybridization.

Animals↗
PubMed1988

Gene amplification and expression of the neu (c-erbB-2) sequence in human mammary carcinoma.

Alterations in the structure and expression of the neu oncogene were investigated in 15 human mammary tumors. In 7 of the samples (46%), amplification by the factor up to 14 was detected, some samples displaying an additional EcoRI restriction fragment at 3.4 kb. In tumor tissue with amplified neu sequences from which intact RNA was available, enhanced expression was noted. Correlation of the molecular data to clinical parameters indicated a correlation of the neu oncogene amplification to tumor grading and thus poor prognosis.

Breast Neoplasms↗
PubMed1987

Loss of heterozygosity and the origin of meningioma.

In some human tumors, loss of particular genes manifested indirectly by loss of heterozygosity for specific RFLPs seems to uncover either heterozygous deletions leading to a gene doses effect or homozygous deletions due to a silent allele at the corresponding locus, both causing the loss of regulatory functions (antioncogenes, suppressor genes). Meningioma, a benign human tumor derived from the coverings of brain and spinal cord, is associated with complete loss, rarely deletion, of one chromosome 22. About 60% of meningiomas exhibit monosomy 22 in all or part of cells; however, about 40% display a normal karyotype. Comparison of constitutional and tumor genomes from 12 patients showed loss of heterozygosity on 22 in three cases, suggesting the involvement of events at the DNA level.

Adult↗
PubMed1987

Enhanced expression of four cellular oncogenes in a human glioblastoma cell line.

Examination of a human glioblastoma cell line displaying a relatively stable karyotype and absence of both copies of chromosome #13 (HeRo) as well as of a SV-40 transformed subline (HeRo-SV) using analysis on the DNA and RNA level showed that both cell lines express high levels of abl, erb B, myc, and Ha-ras mRNA. Neither gene amplification nor gene rearrangement at the loci concerned nor abnormal transcription account for this activation of expression. The possible influence of the deleted sequences in the context of a suppressor gene hypothesis is discussed.

Cell Line↗
PubMed1986

Polysomy of chromosome 7 is correlated with overexpression of the erbB oncogene in human glioblastoma cell lines.

Chromosome analysis in a series of human glioblastoma cell lines (HeRo, HeRo-SV1, A172, T406, T508, T705) has indicated characteristic changes in the karyotype, the most striking and consistent of which is a significant increase in the copy number of chromosome 7, with up to 8 copies per metaphase. As determined by Spurr et al., chromosome 7 represents the genomic locus for the oncogene erbB (7pter-q22). Therefore, we have compared the number of chromosomes 7 to the levels of expression of the erbB oncogene. Interestingly, in all of them erbB-specific mRNA was found to be increased at levels even higher than expected from the number of chromosomes 7 found. In contrast, in an astrocytoma of slightly lower grade of malignancy (cell line T567), neither polysomy 7 nor significant expression of the erbB oncogene was noted.

Astrocytoma↗
PubMed1984

Chromosomes for molecular hybridization. Assignment of repetitive and single copy genes using a rapid filter-fixation method.

Specific recombinant DNA sequences (5S rRNA, B1, albumin) were assigned to flow sorted chromosomes of the Chinese hamster cell line CHV79. For this purpose, a rapid protocol was developed using filterbound chromosomal DNA and probing with various nucleic acids, that allows sequence identification in chromosomes. A flow histogram and a flow karyogram of the CHV79 cell line were established by flow analysis in order to calculate the amount of DNA per CHV79 cell and their chromosomes. Subsequently, metaphase chromosomes or chromosomal groups were fractionated by electronic sorting and a defined number of chromosomes was directly bound to nitrocellulose filters for sequence homology analysis by a dot blot hybridization procedure. This procedure not only allows the assigning of specific DNA sequences to particular chromosomes, it is also applicable to studies of changes in karyotypes, for example translocations of given sequences.

Animals↗
PubMed1983

Cross-reaction of snRNA and an Alu I-like sequence from rat with DNAs from different eucaryotic species.

Sequence homologies to rat U1-snRNA and U2-snRNA were investigated in DNA from 23 eucaryotic species (3 lower eucaryotes, 4 plants, and 16 animals) using dot hybridization at various stringency conditions. Cross-hybridization among very distantly related species in e.g. plants-insects or mold-vertebrates is not the rule; there are, however, examples for stronger homologies like Rattus-Dictyostelium. Furthermore, DNA from all 23 species was analysed for sequence homologies with the repetitive DNA sequence B1 (an Alu I family equivalent) from rat. We observed a wide range of homologies covering some plants and insects, up to vertebrates. Hybridization at increasing stringency conditions revealed species with higher degree of homology to the rat B1 sequence: maize, chicken, and hamster.

Animals↗
PubMed1982

Assignment of snRNA gene sequences to the large chromosomes of rat kangaroo and chinese hamster isolated by flow cytometric sorting.

Chromosomes from a rat kangaroo (Potorous tridactylus) cell line (PtK2) and from a Chinese hamster (Cricetulus griseus) cell line (CHV79) were isolated by means of fluorescence activated flow cytometric sorting. DAPI (4'-6-diamino-2-phenylindole) was used as the DNA specific fluorescent dye. The karyotype of the PtK2 cells which exhibits 13 chromosomes was separated into 6, and the 22 chromosomes of the CHV79 cells were resolved into 11 fractions. DNA extracted from these chromosomal fractions was used for restriction enzyme digestion and blotting on nitrocellulose filters. The blots were challenged with gene probes corresponding to ribosomal RNA (18S and 28S) and small nuclear RNA (U1-snRNA) genes. The rRNA genes were exclusively assigned to chromosomes containing the nucleolus organizing region (in PtK2: X chromosome; in CHV79: chromosomes 4, 5, 6, and 11). - Solely the largest chromosomes in both cell lines hybridized with U1-snRNA indicating that these gene sequences are located on those chromosomes only. Further possible genetic and biochemical applications of this experimental system are discussed.

Animals↗
PubMed1981

The region of transcriptional initiation in Lytechinus variegatus rRNA genes.

A sea urchin ribosomal DNA 1.9 kilobase BamHI fragment adjacent to the 5' end of the 18 S gene has been mapped with the restriction enzymes, XhoI, EcoRi, SmaI and HinfI. A 270 basepair fragment which most likely contains the 5' end of the presumed primary transcript of rRNA was identified by hybridization of [32P]DNA fragments to total nuclear RNA separated on methylmercury hydroxide gels and bound to diazobenzyloxymethyl paper. Under these denaturing conditions the size of Lytechinus variegatus precursor rRNA was determined to be 7.2 kilobases (33 S).

Animals↗