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M Carneiro

Publications and source records attributed to M Carneiro.

30 records · Page 2Linked to original sources
PubMed1991

Isolation, characterization and expression of a gene coding for a 2S albumin from Bertholletia excelsa (Brazil nut).

Two genes, BE2S1 and BE2S2, coding for methionine-rich albumins of Brazil nut (Bertholletia excelsa H.B.K.) have been cloned and their sequence determined. The genes are members of a multigene family and one of them, i.e. BE2S1, codes for one of the dominant 2S isoforms. Its expression is highly regulated during seed development and with respect to tissue specificity. Sequence analysis has shown that the genes contain one intron and that the promoter of BE2S1 shows a canonical TATA motif. The transcription initiation site is located 26 nucleotides downstream from the TATA box. Sequence comparison of the promoter regions of 2S genes from Brassica napus, Arabidopsis thaliana and B. excelsa revealed the presence of TGCA palindromic sequence that appear to be arranged in a 2S-specific manner.

2S Albumins, Plant↗
PubMed1990

Changes in the isoenzyme and kinetoplast DNA patterns of Trypanosoma cruzi strains induced by maintenance in mice.

Culture forms of thirteen Trypanosoma cruzi strains from 4 zymodemes and 9 schizodemes were inoculated and kept by successive passages in C3H mice. The strains were initially from the following zymodemes: 3 from A, 3 from B, 4 from C and 2 from D and 1 from AB mixed zymodemes. After approximately 18 months maintenance the parasites were isolated by hemoculture and again typed according to their isoenzyme and kinetoplast DNA patterns. The zymodeme A strains kept their initial patterns; from the 3 zymodeme B strains, two kept the initial patterns and one changed to zymodeme A; from the 4 zymodeme C, two kept the initial pattern and two changed to zymodeme B; from the 2 zymodeme D strains, one kept the initial pattern and one changed to zymodeme A. The strain from AB mixed zymodeme was reduced to zymodeme. A. The zymodeme changes were accompanied by schizodeme changes. Although not simultaneously, in one T. cruzi strain the parasitemia change was followed by zymodeme and schizodeme changes. The results showed that prolonged maintenance of T. cruzi in mice by successive passages alters the isoenzyme and k-DNA patterns of some strains and that these alterations tend to move towards zymodeme A, suggesting a selective effect of mice over these T. cruzi populations.

Animals↗
PubMed1986

Tissue-specific in vitro transcription from the mouse albumin promoter.

Transcriptionally active nuclear extracts have been prepared from rat liver, brain, and spleen. The adenovirus-2 major late promoter directs efficient transcription by RNA polymerase II in all of these extracts, whereas the promoter of the mouse albumin gene is significantly used only in the liver extract. Albumin sequences located between -170 and -55 are required for this liver-specific in vitro transcription, since deletion of this region results in almost a 100-fold reduction in transcription. In addition, insertion of these sequences in either orientation upstream of the parotid-specific Amy-1 promoter, which is poorly transcribed in the liver extract, increases the activity of this promoter to a level comparable to that observed for the albumin promoter.

Adenoviridae↗
PubMed1984

Accumulation of rare and moderately abundant mRNAs in mouse L-cells is mainly post-transcriptionally regulated.

We have isolated ten complementary DNA recombinant plasmids, five for moderately abundant and five for rare L-cell mRNAs. The plasmids pLc1 to pLc5 contain inserts homologous to mRNAs that accumulate 220 to 640 copies per L-cell, while the plasmids pLc6 to pLc10 are complementary to rare mRNAs that accumulate 5 to 76 copies per L-cell. The cDNA plasmids pLc1 to pLc10 hybridize to cytoplasmic polyadenylated RNAs from several tissues. Thus it appears likely that the ten investigated mRNAs are coding for "housekeeping" functions. The relative transcription rates of the genes Lc1 to Lc10 were estimated by run-off transcription experiments in isolated L-cell nuclei. The results indicate that the transcription rates of genes that specify the moderately abundant mRNAs, Lc1 to Lc5, are not significantly higher than the genes specifying the rare mRNAs, Lc6 to Lc10. Thus the steady-state concentrations of the ten mRNAs investigated are modulated mainly at the post-transcriptional level. Kinetic labelling experiments confirm this conclusion and indicate that differential mRNA stability in the cytoplasm is largely responsible for the variation in accumulation of Lc1 to Lc10 mRNAs. Since housekeeping genes comprise the large majority of active genes, post-transcriptional regulation may well be the prevalent control in eucaryotic cells to determine the individual mRNA levels.

Animals↗
PubMed1982

Evidence for three respiratory terminals in Trypanosoma cruzi epimastigotes.

The respiration of T. cruzi epimastigotes was studied using KCN (1 mM) and NaN3 (5 mM) as inhibitors and glucose (33 mM) as substrate. NaN3 inhibits 18% and KCN 58% of the oxygen uptake when T. cruzi cultures enter the stationary phase. The azide-inhibition pattern closely follows endogenous respiration pattern throughout the different growth phases. Titration of the oxygen uptake with cyanide and azide, with the results treated as Dixon plots, indicated the presence of: a) one respiratory terminal sensitive to both cyanide and azide; b) another cyanide-sensitive but azide-insensitive; c) a third insensitive to both inhibitors. Ethidium bromide (5 micrograms/ml) treatment caused the disappearance of the azide-sensitive terminal in the stationary phase.

Azides↗
PubMedDate not supplied

Rapid size determination of mRNAs complementary to cloned DNA sequences: plaque and colony hybrid-selection of cDNAs.

We describe a novel screening method for the rapid size determination of mRNAs. This method has been used successfully to identify the cDNA and genomic DNA clones that had been constructed using the plasmid vector pBR322 or phage vectors M13mp7 and lambda EMBL3. Poly(A) RNA is reverse-transcribed into 32P-labeled cDNA under conditions that yield a high proportion of full-length cDNA copies. This radioactive cDNA is then hybridized in situ to bacterial colonies or phage plaques harboring recombinant DNA molecules. Colonies or plaques containing sequences complementary to abundant or moderately abundant mRNAs are detected by autoradiography and excised from nitrocellulose filters. The hybridized cDNA is eluted from the filter by alkaline denaturation and sized directly by alkaline agarose gel electrophoresis. The mRNAs characterized thus far by this technique measure between 450 and 2100 nucleotides and account for 0.03% to 15% of the mass of cytoplasmic poly(A) RNA.

Animals↗
PubMedDate not supplied

Biological characterization of Trypanosoma cruzi strains from different zymodemes and schizodemes.

The development in C3H mice of thirteen strains of Trypanosoma cruzi belonging to different zymodemes and schizodemes was studied. Host mortality, virulence, histiotropism, parasitemia and polymorphism of the parasites were recorded. The strains were grouped into: a) high virulence--causing 100% mortality and characterized by predominance of very broad trypomastigotes in the bloodstream at the end of infection; b) medium virulence--causing no mortality and with a predominance of broad trypomastigotes; c) low virulence--causing no mortality with blood forms not described due to the very low parasitemia. During 18 months maintenance the parasitemia curves were kept constant for all strains except one. A direct correlation between either zymodeme or schizodeme and experimental biological properties of T. cruzi strains was not found. However, the parasitemia was subpatent and patent for strains from zymodeme C and the others respectively. Furthermore the high virulence seems to be related to one of two schizodemes found within zymodeme B strains. All strains presenting patent parasitemia independent of shizodeme and zymodeme showed a myotropism towards heart and skeletal muscle with variable inflammatory intensity. The present study confirmed the heterogeneity found by isoenzyme and k-DNA patterns among the strains of T. cruzi isolated from chagasic patients in Bambuí, Minas Gerais State, Brasil.

Animals↗
PubMedDate not supplied

Sexually transmitted diseases in homosexual and bisexual males from a cohort of human immunodeficiency virus negative volunteers (Project Horizonte), Belo Horizonte, Brazil.

Sexually transmitted diseases (STD) are very frequent in the whole world. Males who do not use a condom during their sexual relations are at great risk. We report cases of STD during six months of observation, among homosexual/bisexual males who participate in the Project Horizonte. There were 16 cases of genital warts, 6 cases of human immunodeficiency virus infection, 24 cases of unspecific urethritis, 28 cases of herpes simplex virus infection, 30 cases of syphilis, 58 cases of gonorrhea and 84 cases of pediculosis. We concluded that a condom must be used in all sexual relations and new counseling techniques are needed, to avoid this situation.

Adolescent↗