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Biomedical subjects

E A Braga

Publications and source records attributed to E A Braga.

At least 19 recordsLinked to original sources
PubMed1999

Analysis of NotI linking clones isolated from human chromosome 3 specific libraries.

We have partially sequenced more than 1000 NotI linking clones isolated from human chromosome 3-specific libraries. Of these clones, 152 were unique chromosome 3-specific clones. The clones were precisely mapped using a combination of fluorescence in situ hybridization (FISH) and hybridization to somatic cell or radiation hybrids. Two- and three-color FISH was used to order the clones that mapped to the same chromosomal region, and in some cases, chromosome jumping was used to resolve ambiguous mapping. When this NotI restriction map was compared with the yeast artificial chromosome (YAC) based chromosome 3 map, significant differences in several chromosome 3 regions were observed. A search of the EMBL nucleotide database with these sequences revealed homologies (90-100%) to more than 100 different genes or expressed sequence tags (ESTs). Many of these homologies were used to map new genes to chromosome 3. These results suggest that sequencing NotI linking clones, and sequencing CpG islands in general, may complement the EST project and aid in the discovery of all human genes by sequencing random cDNAs. This method may also yield information that cannot be obtained by the EST project alone; namely, the identification of the 5' ends of genes, including potential promoter/enhancer regions and other regulatory sequences

Animals↗
PubMed1998

[Association of allele polymorphism of dopamine d2 receptors with schizophrenic and affective disorders].

DRD2 Taq polymorphism has been studied in the samples from 214 patients (119 males, 95 females, mean age 37.8 +/- 13.6) and of 96 controls (50 males, 46 females, mean age 40.7 +/- 20.0). The latter group comprised 75 unrelated controls and 21 healthy first degree relatives of schizophrenic patients. All the patients were diagnosed according to ICD-10 and have been divided into 4 groups: paranoid schizophrenics (n = 102), schizotypic patients (n = 25), patients with schizoaffective psychoses (n = 40) and affective disorders (n = 47). Taq1A DRD2 polymorphism was represented by 3 genotypes: A1A1, A1A2, A2A2 (allele A2 was a result of nucleotide substitution). The frequencies of genotypes in affected group didn't significantly differ from a control one. However, a frequency of A2A2 genotype (0.45) in a group of paranoid schizophrenics was significantly higher, than in the patients with schizoaffective psychoses (0.22) or in a control group (0.26), but was similar to that of the patients with schizotypic or affective disorders (0.4). A2A2 DRD2 genotype seems to be a potential genetic factor of susceptibility to schizophrenia.

Adult↗
PubMed1991

[Assessment of interleukin-1 beta mRNA expression in the norm and pathology].

We investigated cytoplasmic RNA from the peripheral blood cells of pollinosis patients. Increased levels of IL-I mRNA were registered in neutrophils of patients suffering from pollinosis for a long time. Neutrophils from patients at the time of exacerbation of pollinosis responded to stimuli less than the cells from healthy donors. During remission the activated neutrophils from pollinosis patients and those from healthy donors had same levels of IL-I mRNA.

Cytoplasm↗
PubMed1991

[Evaluation of the activity of cytokine genes--a new diagnostic test in immunology].

The increased level of IL-1 mRNA was discovered in neutrophils of patients suffering from pollinosis for a long time and responding poorly to specific immunotherapy. Moreover, neutrophils from patients with exacerbation of pollinosis responded to stimuli less than cells from healthy donors. In remission, the activated neutrophils from pollinosis patients and healthy donors had the same levels of IL-1b mRNA. Tumor necrosis factor alpha expression was unchanged in neutrophils of pollinosis patients. Changes in the status of cells from patients were detected with a simple procedure of dot hybridization. Peripheral blood cells were used as available material. This allows one to hope that the approach can be used for analyzing the patients' immune status in choosing the treatment course as well as for controlling the treatment effect.

Cells, Cultured↗
PubMed1988

Cell differentiation as assayed by the topography and number of ribosomal genes.

In situ hybridization, Ag-staining and electron microscopy were used to study the distribution of ribosomal genes in isolated nuclei of rat cerebellar cells and the correspondence of the ribosomal genome topography to the nucleolar structure. rDNA-DNA autoradiography revealed clusters of silver grains, as well as diffuse groups and rows. The cluster frequencies corresponded to the frequencies of nucleoli on Ag-stained slides. Competitive hybridization in situ using unlabelled rat rRNA and hybridization with a nonspacer rDNA fragment showed that the diffuse groups and rows of grains also correspond to the ribosomal genes. Spatial organization of the ribosomal genome in the Purkinje cells differs from that in the other cerebellar neurons and glial cells. A 1.5-fold redundancy of the ribosomal genes was found in some Purkinje cells, while most of these as well as microneurons contained the diploid value of the genes.

Animals↗
PubMed1986

Nucleotide sequence analysis of the spacer regions flanking the rat rRNA transcription unit and identification of repetitive elements.

We investigated the organization of the rat rDNA non-transcribed spacer (NTS) by determining the sequence of large NTS segments located upstream (2501 bp) and downstream (4025 bp) from the rRNA transcription unit. We identified four B2-like and two ID mobile elements. They may be grouped in three pairs with the members of each pair located in the upstream and downstream NTS. The ID sequences are identical to the consensus sequence, while the pairs of B2-like elements show 85% and 50/65% homology to the consensus B2 sequence. The proximal part of the downstream NTS contains a region of widely diverged SalI tandem repeats. A considerable part of the analyzed upstream and downstream NTS sequences is constituted by different types of simple sequences and long poly(purine) X poly(pyrimidine) tracts. These data show that the rat rDNA NTS regions flanking the rRNA transcription unit are characterized by a combination of short interspersed (B2-superfamily) and various simple sequences.

Animals↗
PubMed1986

[Intra- and interpopulation heterogeneity of the cerebellar nerve cells in topography and ribosomal gene content].

Using the method of in situ hybridization of ribosomal DNA with DNA of isolated nuclei, a study was made of localization and relative content of ribosomal genes in the Purkinje cells and other cells of the rat cerebellum. It has been shown that various cells of cerebellum have, on the average, the same number of ribosomal genes. A subpopulation with amplified ribosomal genes have been found among the nuclei of Purkinje's cells.

Animals↗
PubMed1985

Structural organization of rat ribosomal RNA genes: interspersed sequences and their putative role in the alignment of nucleosomes.

We have observed four regions containing highly repetitive interspersed sequences in the nontranscribed spacer (NTS) of the rat rRNA genes. Two of them (A and B) are located at a distance of 3-5 kb upstream from the transcription start point and two others (C and D) at a distance of 2-5 kb downstream from the 3' end of the 28S rRNA gene. These repetitive sequences are widely dispersed in the genome and are included both in small-copy regions and in the families of extended reiterated sequences. The sequences of three fragments were determined: one from the C2 region, 1100 bp in length and two from A and C1 regions, 110-120 bp long. These regions are characterized by the presence of 'simple' sequences, such as (AC)n, (ACC)n, (GAG)n, (GGGA)n, (TAAG)n, and also of long blocks, (G)n and (A)n. In the C2 region two palindromes, 16 and 14 nt long, were found, one of them including a XhoI site. Mobile element B2 was observed in regions B and C. All four regions, A, B, C and D, contain sets of simple sequences, among which some common elements have been found. Theoretical prediction of the nucleosomal disposition in the C region indicates that the combination of simple sequences existing in the given area secures fixed positions of the nucleosomes, one of the nucleosomes being formed on the B2 element. Moreover, a striking periodicity, with the repeat length close to that of the rat nucleosomal DNA, has been observed. A hypothesis is put forward that the simple sequences can dictate the location of nucleosomes on the adjoining DNA sequences, thereby regulating the gene activity.

Animals↗
PubMed1984

Sequence heterogeneity in the internal transcribed spacers of two rat ribosomal DNA clones.

The sequence of one cloned rat rDNA segment is determined, encompassing the 3'-terminal part of 18 S rDNA (231 bp), ITS 1 (1072 bp), 5.8 S rDNA (156 bp), ITS 2 (771 bp) and the 5'-terminal part of 28 S rDNA (210 bp). Comparison with a distinct clone of the same rDNA segment reveals the identity of the rRNA gene sequences and considerable heterogeneity in both ITS 1 and ITS 2. The heterogeneities include mainly single base-pair changes (23 deletions or insertions and 14 substitutions) distributed all along the ITS sequences.

Animals↗
PubMed1982

Structural organization of rat ribosomal genes restriction endonuclease analysis of genomic and cloned ribosomal DNAs.

Structural organization of the rat ribosomal repeating unit was studied using hybridization of blotted restriction fragments of total rat DNA with alpha-32P-labeled cDNA probe synthesized on the 18S and 28S rRNAs. A detailed restriction endonuclease map was constructed, the 18S and 28S rRNA genes mapped and the sizes of the rat ribosomal repeating units determined. Considerable site heterogeneity of rat rDNA was revealed in both nontranscribed and external transcribed spacers. Recombinant phages containing the whole set of transcribed regions and a considerable part of a nontranscribed spacer of the rDNA were selected from the rat gene library. The restriction maps of the cloned rDNA fragments are in good agreement with the map constructed by Southern's technique, add to this map and support the existence of site heterogeneity in ribosomal repeating units. Proximal to the 3'-end of the 28S rRNA gene an internally repetitive region was found, each repeating unit being equal to approx. 150 bp. The site for transcription initiation was mapped 4.0-4.5 kb upstream from the 5'-end of the 18S rRNA gene. Frequently reiterated interspersed sequences were found in the nontranscribed spacer at approx. 2-3 kb distance from both ends of the transcribed region.

Animals↗
PubMed1981

Physical and functional mapping of rat-liver mitochondrial DNA.

Rat-liver mitochondrial DNA (mtDNA) contains 2 cleavage sites of the restriction endonuclease Xbal. The molecular sizes of restriction fragments are 6.6 X 10(6) and 3.7 X 10(6) D. The results of partial cleavage of mtDNA with EcoRI allow the fragment F (0.32 X 10(6) D) to be localized in the sequence ABCEGFHDA. The functional map of mtDNA is constructed for two genes of the ATP-ase mRNAs from rat-liver mitochondria. Molecular hybridization shows that the ATPase genes are located in fragment B and in the GEHD area of mtDNA EcoRI cleavage.

Adenosine Triphosphatases↗
PubMed1978

Physical mapping of bacteriophage lambda DNA with restriction endonuclease HpaI.

The restriction endonuclease from Haemophilus parainfluenzae, endoR.HpaI cleaves lambdacI857s7 DNA into 14 fragments. The sizes of these fragments were determined and a physical map was constructed. The ordering of the fragments was carried out using different deletion and substitution mutants of lambda phage, double cleavages with another restriction enzyme, endoR.BamHI, and partial protection of individual HpaI recognition sites by the antibiotics distamycin A and actinomycin D. HpaI produces fragments from the left arm of the lambda DNA genome, which may help in investigating the structure and function of this part of the phage.

Chromosome Mapping↗
PubMed1976

Protection of particular cleavage sites of restriction endonucleases by distamycin A and actinomycin D.

It is shown here that distamycin A and actinomycin D can protect the recognition sites of endo R.EcoRI, EcoRII, HindII, HindIII, HpaI and HpaII from the attack of these restriction endonucleases. At proper distamycin concentrations only two endo R.EcoRI sites of phage lambda DNA are available for the restriction enzyme--sRI1 and sRI4. This phenomenon results in the appearance of larger DNA fragments comprising several consecutive fragments of endo R.EcoRI complete cleavage. The distamycin fragments isolated from the agarose gels can be subsequently cleaved by endo R.EcoRI with the yield of the fragments of complete digestion. We have compared the effect of distamycin A and actinomycin D on a number of restriction endonucleases having different nucleotide sequences in the recognition sites and established that antibiotic action depends on the nucleotide sequences of the recognition sites and their closest environment

Base Sequence↗