Biomedical subjects

M Rocchi

Publications and source records attributed to M Rocchi.

At least 199 records · Page 11Linked to original sources

PubMed1991

A human chromosome 9-specific alphoid DNA repeat spatially resolvable from satellite 3 DNA by fluorescent in situ hybridization.

We have isolated a DNA clone (pMR9A) that identifies an alphoid DNA subset specific for chromosome 9. This alphoid subset is characterized by a dimeric organization as revealed by Southern blot analysis after digestion with HaeIII, HinfI, or StuI. Nonradioactive in situ hybridization demonstrated that pMR9A hybridizes only to the centromeric region of chromosome 9 and reveals chromosome 9 aneuploidies in interphase nuclei. In addition, the probe detects quantitative differences in alpha satellite DNA on chromosome 9, but these quantitative differences are not correlated with the size of the heterochromatic region. Double-labeling experiments, using a chromosome 9-specific satellite 3 clone and pMR9A, enabled us spatially to distinguish the alphoid and satellite 3 domains on metaphase chromosomes after treatment of the cultures with 5-azacytidine.

Aneuploidy↗

PubMed1991

Chromosomal assignment of human O6-methylguanine-DNA-methyltransferase gene by hamster-human somatic cell hybrids.

Using an in vitro assay to measure O6-methylguanine-DNA-methyltransferase (MT) activity in cell extracts from a panel of human-hamster cell hybrids, we were able to locate the human MT gene on chromosome 10. Chinese hamster cells have little or no MT activity and the presence of human chromosome 10 was a necessary condition for MT activity in cell hybrids. In some cell hybrids carrying chromosome 10, however, MT activity was not higher than that of hamster cells. As an explanation for this result, genetic determinants repressing MT expression and/or activity might be present in other human chromosomes carried by MT-negative cell hybrids. Partial hyperploidy of the hamster karyotype, variable activity of the parental human cell lines and changes during subculturing of the cell hybrids might also account for the lack of enzymatic activity in chromosome 10 containing hybrids.

Animals↗

PubMed1991

Isolation and characterization of the CRIPTO autosomal gene and its X-linked related sequence.

We have previously reported on the identification of a cDNA clone encoding a novel human growth factor, named "CRIPTO," that is abundantly expressed in undifferentiated human NTERA-2 clone D1 (NT2/D1) and mouse (F9) teratocarcinoma cells. We now report the organization and nucleotide sequence of two related genomic sequences. One (CR-1) corresponds to the structural gene encoding the human CRIPTO protein expressed in the undifferentiated human teratocarcinoma cells, and the other (CR-3) corresponds to a complete copy of the mRNA containing seven base substitutions in the coding region representing both silent and replacement substitutions. The 440 bp 5' to the CAP site of CR-1 are preserved in CR-3. CR-1 maps to chromosome 3, and CR-3 maps to Xq21-q22. Southern blot analysis reveals that multiple CRIPTO-related DNA sequences are present in the human as well as in the mouse genome.

Amino Acid Sequence↗

PubMed1990

Physical mapping of the human chromosome 11q23 region containing the ataxia-telangiectasia locus.

Two breakpoints within chromosome 11q23 were characterized with 29 DNA probes to establish a physical map of the region. This region is notable in that it contains at least 14 functional genes which are also syntenic in the mouse (chromosome 9). Chromosome 11q23 includes these markers: STMY, CLG, NCAM, DRD2, APOA1, APOC3, APOA4, CD3E, CD3D, CD3G, PBGD, THY1, ets-1, and cbl-2. The two breakpoints, herein called "X;11" and "4;11," defined a region of approximately 8 cM containing the APO and CD3 complexes as well as the polymorphic marker D11S29. DRD2 localized centromeric to the X;11 breakpoint despite evidence for close genetic linkage to D11S29, suggesting that DRD2 lies close to the X;11 breakpoint. THY1, PBGD, and cbl-2 localized telomeric to the 4;11 breakpoint and thus to the [D11S29--APO--CD3] grouping as well. The physical map helps to correlate the cytogenetic and linkage maps of this region. It also suggests that the human 11q23 syntenic grouping is inverted with respect to its murine counterpart. Based on this physical map and on our primary linkage map of the 11q23 region, we are able to confirm a preliminary localization of the gene for ataxia-telangiectasia group A (ATA) to a region centromeric to the interval defined by D11S144 (pYNB3.12) and THY1.

Animals↗

PubMed1990

Probes for CpG islands on the distal long arm of the human X chromosome are clustered in Xq24 and Xq28.

We have isolated and characterized 55 EagI-containing genomic DNA clones from the distal long arm of the human X chromosome. The presence of additional sites for rare-cutter restriction enzymes and the demethylation of the corresponding genomic DNA demonstrate that at least 30 clones correspond to CpG islands of the Xq24-Xqter region. All clones were regionally mapped with a hybrid panel. The majority are in Xq28 and Xq24 (18 and 14 clones, respectively), 15 are in the Xq26-Xq27 interval, and none is in Xq25. This analysis demonstrates a nonuniform distribution of CpG islands that may reflect the distribution of coding regions in this part of the genome.

Animals↗

PubMed1990

Chromosome-specific subsets of human alphoid DNA identified by a chromosome 2-derived clone.

We have cloned an alphoid DNA fragment, pBS4D, from the DNA of a human-hamster hybrid cell line containing chromosome 2 as its only cytologically detectable human component. Under high stringency conditions, pBS4D hybridized in situ mostly to chromosome 2 and to a lesser extent to chromosomes 18 and 20. Restriction analysis using the DNA from selected somatic hybrid cell lines revealed that the genomic organization of this alphoid DNA differs on each of these three chromosomes.

Animals↗

PubMed1990

Site-specific integration by adeno-associated virus.

Cellular sequences flanking integrated copies of the adeno-associated virus (AAV) genome were isolated from a latently infected clonal human cell line and used to probe genomic blots derived from an additional 21 independently derived clones of human cells latently infected with AAV. In genomic blots of uninfected human cell lines and of primary human tissue, each flanking-sequence probe hybridized to unique bands, but in 15 of the 22 latently infected clones the flanking sequences hybridized not only to the original fragments but also to a total of 36 additional species. AAV probes also hybridized to 22 of these new bands, representing 11 of the 15 positive clones, but never to the fragment characteristic of uninfected cell DNA. From these data we conclude that the AAV genome preferentially integrates into a specific region of the cellular genome. We have determined that the integration site is unique to chromosome 19 by somatic cell hybrid mapping, and this sequence has been isolated from uninfected human DNA.

Cell Line↗

PubMed1990

Assignment of cathepsin E (CTSE) to human chromosome region 1q31 by in situ hybridization and analysis of somatic cell hybrids.

A full length cathepsin E (CTSE) cDNA clone was used to assign the corresponding gene to human chromosome region 1q31 by in situ hybridization. Southern blot analysis of DNA from three independent human x rodent somatic cell hybrids containing X;1 translocations confirmed the assignment of the CTSE gene to the distal region of the long arm of chromosome 1.

Blotting, Southern↗

PubMed1990

Mental retardation in heterozygotes for the fragile-X mutation: evidence in favor of an X inactivation-dependent effect.

The still debated question of whether the expression of mental retardation in heterozygous carriers of the Martin-Bell syndrome is influenced by X inactivation has been investigated in a group of phase-known double heterozygotes for the FRA-X mutant and the G6PD Mediterranean variant. In these individuals, the number of somatic cells (fibroblasts or red cells) with an active FRA-X chromosome could be assessed through the G6PD phenotype at the single-cell level. The data reported indicate a significant inverse correlation between the IQ level (as measured by the Wechsler-Bellevue test) and the percentage of fibroblast cells with an FRA-X active chromosome. In contrast, no significant correlation was found when the IQ level and red cell data were compared, thus suggesting the occurrence of somatic selection against hematopoietic stem cells with an active FRA-X chromosome.

Dosage Compensation, Genetic↗

PubMed1990

A human alpha satellite DNA subset specific for chromosome 12.

We have isolated a DNA clone (pBR12, locus D12Z3) which identifies an alphoid subset specific for chromosome 12. This alphoid subset has an EcoRI periodicity of 680 bp and is characterized by a higher-order repeat of about 1.4 kb (eight basic units of about 170 bp each) as revealed by several restriction enzymes. The sequence analysis confirmed the alphoid nature of pBR12 and the dimeric organization.

Blotting, Southern↗

PubMed1990

Physical mapping of new DNA probes near the fragile X mutation (FRAXA) by using a panel of cell lines.

The fragile X syndrome is a very common disorder, but there has been little progress toward isolating the fragile X mutation (FRAXA). We describe a panel of 14 somatic cell hybrid lines, lymphoblastoid cell lines, and peripheral lymphocytes with X-chromosome translocation or deletion breakpoints near FRAXA. The locations of the breakpoints were defined with 16 established probes between pX45d (DXS100) and St14-1 (DXS52). Seven of the cell lines had breakpoints between the probes RN1 (DXS369) and U6.2 (DXS304), which flank FRAXA at distances of 3-5 centimorgans. The panel of cell lines was used to localize 16 new DNA probes in this region. Six of the probes-VK16, VK18, VK23, VK24, VK37, and VK47--detected loci near FRAXA, and it was possible to order both the X-chromosome breakpoints and the probes in relation to FRAXA. The order of probes and loci near FRAXA is cen-RN1,VK24-VK47-VK23-VK16,FRAXA-++ +VK21A-VK18-IDS-VK37-U6.2-qter. The breakpoints near FRAXA are sufficiently close together that probes localized with this panel can be linked on a large-scale restriction map by pulsed-field gel electrophoresis. This panel of cell lines will be valuable in rapidly localizing other probes near FRAXA.

Animals↗

PubMed1989

Biochemical diagnosis of Hunter syndrome on Epstein-Barr virus-transformed lymphoblastoid cell lines.

Long-term lymphoblastoid cell lines have been established from a patient with Hunter syndrome, from his mother, an obligate heterozygote, and from several control individuals. Biochemical analyses show that lymphoblastoid cells represent a suitable biological material for the diagnosis of hemizygous, affected males and for heterozygous females: clonal analysis demonstrates the mosaicism predicted by the Lyon hypothesis.

Cell Line, Transformed↗

PubMed1989

Impairment of capping in lymphoblastoid cell lines of Duchenne patients indicates an intrinsic cellular defect.

Duchenne muscular dystrophy (DMD) is a lethal sex-linked degenerative disorder of the muscle in man. Generalized cell membrane abnormalities seem to be involved in the pathogenesis of the disease; in particular, the impairment of lymphocyte capping capacities has been repeatedly confirmed. To clarify whether capping impairment is a consequence of factors related to the activity of the disease or an expression of an intrinsic cellular defect, we have investigated the capping capacities of DMD EBV-transformed cell lines. The results indicate a significant impairment of capping capacity in cultured cell lines, providing evidence for an intrinsic cell deficiency in DMD.

Antibodies, Monoclonal↗

PubMed1989

Assignment of human aldolase C gene to chromosome 17, region cen----q21.1.

The mapping of the gene coding for human aldolase C has been studied using a specific cDNA probe and genomic blots from a panel of human-hamster somatic cell hybrids. The results show that the aldolase C gene is on chromosome 17. In situ experiments have restricted the mapping to the region 17cen----q21.1. Using the same panel of human-hamster somatic cell hybrids, we have confirmed the localization of aldolase A and B on chromosomes 16 and 9, respectively.

Animals↗

PubMed1989

Regional mapping of RBP4 to 10q23----q24 and RBP1 to 3q21----q22 in man.

The human gene coding for RBP4 has been assigned to 10q23----24 using a panel of somatic cell hybrids and in situ hybridization experiments. The mapping of the human RBP1, previously assigned by our group to chromosome 3 using a panel of somatic cell hybrids, was restricted to the region 3q21----22 using in situ experiments and Southern blots of genomic DNA from a hybrid retaining a portion of chromosome 3.

Blotting, Southern↗

PubMed1989

A human alphoid DNA clone from the EcoRI dimeric family: genomic and internal organization and chromosomal assignment.

We isolated an alpha satellite DNA clone (pC1.8), 17 kb long, which is composed exclusively of tandemly repeated 340-bp EcoRI fragments. Hybridization studies using 37 random EcoRI dimers subcloned from pC1.8 showed that they are heterogeneous. The sequence of 5 dimers, 3 of them adjacent, confirmed this observation and showed that the heterogeneity is more accentuated among the second monomers. The chromosomal assignment under high stringency conditions showed that this alphoid subset is located on chromosomes 1, 5, and 19. No conditions that eliminate the hybridization on any one of those chromosomes were found. This suggests that, in contrast to many other chromosome-specific alpha satellite subsets, the single chromosome subsets of this family are virtually indistinguishable by hybridization techniques.

Base Sequence↗

PubMed1989

Molecular characterization of human X/Y translocations suggests their aetiology through aberrant exchange between homologous sequences on Xp and Yq.

Several DNA sequences from two homologous regions, localized on the distal part of the human X chromosome short arm and on the long arm of the Y chromosome, have been hybridized to DNAs from seven human-rodent hybrids containing human X; Y translocation chromosomes. Molecular characterization of the translocated chromosomes has revealed, in all but one case, transfer of the Y cluster of sequences and complete deletion of the corresponding X-chromosomal sequences. The possible role of X/Y homology in the aetiology of X; Y translocations is proposed.

Cell Line↗

PubMed1989

The gene coding for proteins HC and HI-30 of inter-alpha-trypsin inhibitor maps to 9q22.3----q33.

Proteins HC and HI-30 of inter-alpha-trypsin inhibitor light chain are two plasma proteins. They are encoded by the same monocistronic mRNA. Their function is probably related to the regulation of immunologic and/or inflammatory responses. Using a genomic DNA probe and a panel of somatic cell hybrids we have mapped the gene coding for the proteins to chromosome 9. In situ hybridization experiments refined the assignment to the region 9q22.3----q33.

Alpha-Globulins↗