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J M Lopes

Publications and source records attributed to J M Lopes.

At least 55 records · Page 3Linked to original sources
PubMed1996

The yeast UME6 gene is required for both negative and positive transcriptional regulation of phospholipid biosynthetic gene expression.

In Saccharomyces cerevisiae, regulation of the phospholipid biosynthetic genes, INO1, CHO1, CHO2 and OPI3, is known to occur at the level of transcript abundance. Derepression in response to inositol deprivation requires the INO2 and INO4 regulatory genes. Repression in response to inositol supplementation requires the OPI1 regulatory gene. Here, we examined the role of the UME6 global negative regulatory gene in expression of the phospholipid biosynthetic genes. These studies were stimulated by the finding that the INO1 promoter included a UME6 cognate cis-acting regulatory sequence (URS1). We found that the UME6 negative regulatory gene was involved in regulation of phospholipid biosynthetic gene expression through two distinct regulatory pathways. One pathway was the direct repression of INO1 expression through the URS1 element. Surprisingly, the UME6 gene was also required for derepression of CHO1, CHO2 and OPI3 gene expression. Consistent with this observation, the UME6 gene was required for wild-type levels of expression of the INO2 positive regulatory gene. Therefore, the UME6 gene has both a negative and a positive role in regulating phospholipid biosynthesis.

Base Sequence↗
PubMed1995

Regulation of yeast phospholipid biosynthetic gene expression in response to inositol involves two superimposed mechanisms.

Transcription of phospholipid biosynthetic genes in the yeast Saccharomyces cerevisiae is maximally derepressed when cells are grown in the absence of inositol and repressed when the cells are grown in its presence. We have previously suggested that this response to inositol may be dictated by regulating transcription of the cognate activator gene, INO2. However, it was also known that cells which harbor a mutant opi1 allele express constitutively derepressed levels of target genes (INO1 and CHO1), implicating the OPI1 negative regulatory gene in the response to inositol. These observations suggested that the response to inositol may involve both regulation of INO2 transcription as well as OPI1-mediated repression. We investigated these possibilities by examining the effect of inositol on target gene expression in a strain containing the INO2 gene under control of the GAL1 promoter. In this strain, transcription of the INO2 gene was regulated in response to galactose but was insensitive to inositol. The expression of the INO1 and CHO1 target genes was still responsive to inositol even though expression of the INO2 gene was unresponsive. However, the level of expression of the INO1 and CHO1 target genes correlated with the level of INO2 transcription. Furthermore, the effect of inositol on target gene expression was eliminated by deleting the OPI1 gene in the GAL1-INO2-containing strain. These data suggest that the OPI1 gene product is the primary target (sensor) of the inositol response and that derepression of INO2 transcription determines the degree of expression of the target genes.

Base Sequence↗
PubMed1995

A cDNA from Schizosaccharomyces pombe encoding a putative enolase.

Here we report the isolation of an enolase (Eno)-encoding cDNA clone from Schizosaccharomyces pombe. The deduced amino acid (aa) sequence of the 1.4-kb cDNA shares identifies with a number of Eno from Escherichia coli to humans. The highest degree of similarity is to the known Eno from Saccharomyces cerevisiae and an Eno from Candida albicans. Northern blot analysis identified a single transcript of approx. 1.4 kb, which was most abundant when cells were grown in media with glucose as the carbon source, as opposed to glycerol/lactate or ethanol.

Amino Acid Sequence↗
PubMed1995

Physical map locations of the phospholipid biosynthetic structural and regulatory genes of Saccharomyces cerevisiae.

Here we report the physical map locations of five genes required for phospholipid biosynthesis in Saccharomyces cerevisiae. These include four structural genes (INO1, CHO2, OPI3 and PIS1) and one global negative regulatory gene (UME6). Collectively, this information completes the mapping of all phospholipid biosynthetic structural and regulatory genes identified to date.

Chromosome Mapping↗
PubMed1995

Autoregulated expression of the yeast INO2 and INO4 helix-loop-helix activator genes effects cooperative regulation on their target genes.

In the yeast Saccharomyces cerevisiae, the phospholipid biosynthetic genes are highly regulated at the transcriptional level in response to the phospholipid precursors inositol and choline. In the absence of inositol and choline (derepressing), the products of the INO2 and INO4 genes form a heteromeric complex which binds to a 10-bp element, upstream activation sequence INO (UASINO), in the promoters of the phospholipid biosynthetic genes to activate their transcription. In the presence of inositol and choline (repressing), the product of the OPI1 gene represses transcription dictated by the UASINO element. Curiously, we identified a UASINO-like element in the promoters of both the INO2 and INO4 genes. The presence of the UASINO element in these two promoters suggested that the mechanism for the inositol-choline response would involved regulating expression of the two activator genes. Using a cat reporter gene, we find that INO2-cat expression was regulated 12-fold in response to inositol and choline but that INO4-cat was constitutively expressed. We further observed that INO2-cat was not expressed in either an ino2 or an ino4 mutant strain and was constitutively overexpressed in an opi1 mutant strain. Expression of the INO4-cat gene was affected only by mutation in the INO4 gene itself. Therefore, INO2-cat transcription is regulated by the products of both the INO2 and INO4 genes whereas INO4 must interact with another protein to activate its own transcription. Our data show that derepression of phospholipid biosynthetic gene expression involves two mechanisms: increasing the levels of the INO2 and INO4 gene products and inactivating the OPI1-mediated repression mechanism. We propose a model suggesting that this dual mechanism of regulation accounts for the observed cooperative stimulation of IN01 and CH01 gene expression (phospholipids biosynthetic genes).

Base Sequence↗
PubMed1995

Phototherapy units in Brazil: are they effective?

The irradiance delivered by a phototherapy unit is an important contributing factor to its efficacy. However, measurement of irradiance during phototherapy requires the use of a photometer which is rarely available in the nurseries of developing countries. We assessed the irradiance of phototherapy units both in the laboratory and in all public hospitals of the City of Rio de Janeiro and found that: a) there is no consensus among companies manufacturing phototherapy units as to the number of fluorescent lights to be used in an equipment since this number varied from 4 to 8, b) over 1/3 of the phototherapy units analysed had 1 or more burnt out lamps, c) the mean irradiance delivered by phototherapy units was 2.36 +/- 0.75 muw/cm2/nm (0.6 to 4.4 muw/cm2/nm) which is considerably lower than the dose currently recommended for clinical efficacy. These results may be relevant to other developing countries where phototherapy meters are seldomly available and irradiance is not routinely measured.

Brazil↗
PubMed1994

Role of adenosine in the hypoxic ventilatory response of the newborn piglet.

The role of intracerebral adenosine levels in the control of ventilatory response to hypoxia was explored in 15 spontaneously breathing intubated piglets, 1-5 days old, sedated with chloral hydrate. Respiration was recorded via by a pneumotachograph. In all animals exposed to hypoxia (12% O2) for 10 minutes. There was an initial increase in ventilation followed by a late decrease (the biphasic ventilatory response). Both intravenous caffeine citrate (20 mg/kg) and an FiCO2 of 0.05 separately abolished or attenuated the late ventilatory depression associated with hypoxia. In the same piglets, the administration of 10 micrograms dipyridamole, a competitive inhibitor of adenosine receptors, directly into the cerebral ventricles abolished the hyperventilatory response to hypoxia. Conversely, the use of 20 micrograms intraventricular 8-phenyltheophylline abolished the late ventilatory depression associated with hypoxia. Neither drug had a direct effect on ventilation at the time of injection. These results suggest that adenosine is a part of the diphasic ventilatory response to hypoxia.

Adenosine↗
PubMed1994

Immunohistochemical profile of synovial sarcoma with emphasis on the epithelial-type differentiation. A study of 49 primary tumours, recurrences and metastases.

The relationship between biphasic (BSS) and monophasic (MSS) subtypes of synovial sarcoma (SS) as well as the relationship between cells of solid/glandular areas and the spindle cells of BSS remain controversial. In order to further evaluate the immunohistochemical phenotype of SS we studied 34 primary tumours (15 BSS; 19 MSS), 7 recurrences (4 from primary BSS; 3 from primary MSS) and 8 metastases (7 BSS; one MSS), using several antibodies (EMA, CEA, keratins 1, 4, 5/6, 7, 8, 13, 18, 19, 20, vimentin, collagen IV and laminin) that work in paraffin-embedded material. Spindle cells outside solid/glandular areas of BSS and in MSS showed immunoreactivity for keratins 5/6, 7, 8, 18 and 19. The transition of solid/glandular areas to surrounding spindle cells also showed keratin staining and failed to show a distinct separation regarding the immunoreactivity for laminin and collagen IV. Peripheral cells of solid/glandular areas were immunoreactive for vimentin. No major differences were observed between immunophenotypical cell profiles of BSS and MSS, apart from the exclusive immunostaining of solid/glandular areas of BSS for keratin 13 and CEA. Downgrading of keratin and extracellular matrix antigens immunoreactivity was observed when primary tumours were compared to recurrent and/or metastatic tumours of both subtypes (MSS and BSS). We conclude that SS should be regarded as carcinomas of soft tissues with an immunohistochemical phenotype depending on the degree of epithelial differentiation: spindle cells (MSS and BSS) predominantly expressing simple keratins, and poorly differentiated (solid/glandular) as well as well-differentiated (glandular) areas (BSS) expressing, in addition, complex epithelial-type keratins.

Adolescent↗
PubMed1994

Influence of amino-acid concentration in the culture medium on the rate of amino-acid incorporation into protein and amino-acid oxidation of cultured chicken hepatocytes.

Hepatocytes from a 70-d-old male broiler were dissociated using a modified technique of double perfusion with an isotonic solution through the jejunum mesenteric and pancreatic veins followed by collagenase perfusion. A basal medium was made up with the same amino-acid composition of the whole chicken egg, diluted 25 times. Dilutions of 1:1, 1:2, 1:4, 1:20, 1:40 and 1:80 of the basal medium constituted the experimental treatments. Amino-acid incorporation into protein and amino-acid oxidation were determined by counting the radioactivity of [3H]-leucine present in cellular proteins and the 14CO2 released by the cells for 6 periods of time. The rate of amino-acid incorporation into cellular proteins was proportional to the concentration of amino acids in the culture medium, indicating their effect on the regulation of protein synthesis. At least 6 h incubation is needed to reach the maximal values of incorporation. Media containing large amounts of amino acids also showed higher values for oxidation, but the ratio oxidation/incorporation was higher when the amino-acid concentration in the medium was low.

Amino Acids↗
PubMed1994

A pleiotropic phospholipid biosynthetic regulatory mutation in Saccharomyces cerevisiae is allelic to sin3 (sdi1, ume4, rpd1).

Three mutants were identified in a genetic screen using an INO1-lacZ fusion to detect altered INO1 regulation in Saccharomyces cerevisiae. These strains harbor mutations that render the cell unable to fully repress expression of INO1, the structural gene for inositol-1-phosphate synthase. The Cpe-(constitutive phospholipid gene expression) phenotype associated with these mutations segregated 2:2, indicating that it was the result of a single gene mutation. The mutations were shown to be recessive and allelic. A strain carrying the tightest of the three alleles was examined in detail and was found to express the set of co-regulated phospholipid structural genes (INO1, CHO1, CHO2 and OP13) constitutively. The Cpe- mutants also exhibited a pleiotropic defect in sporulation. The mutations were mapped to the right arm of chromosome XV, close to the centromere, where it was discovered that they were allelic to the previously identified regulatory mutation sin3 (sdi1, ume4, rpd1, gam2). A sin3 null mutation failed to complement the mutation conferring the Cpe- phenotype. A mutant harboring a sin3 null allele exhibited the same altered INO1 expression pattern observed in strains carrying the Cpe- mutations isolated in this study.

Alleles↗
PubMed1994

Interaction of the constituents of alcoholic beverages in the promotion of liver damage.

Little has been studied of the adverse effects of the exposure of the liver to the interaction of ethanol with its congeners and acetaldehyde, coexisting in the contents of alcoholic beverages. Twenty four male Wistar rats were divided into four groups. Two groups (SH/DA; SH/FA) were submitted to daily treatment with synthetic hydroalcoholic solutions containing ethanol, methanol, higher alcohols and acetaldehyde in the same proportions as those found in most common distilled and fermented alcoholic beverages; the third group (SH/EA) was treated with a hydroalcoholic solution of ethanol; the fourth group served as control and received an equivalent volume of an isocaloric solution of dextrose. All the animals were killed at the end of the 9th week of the experiment. The ratio between the liver weight and body weight was found to be lower in the treated animals than in the control group. The histology of the liver was altered in the three groups which were submitted to treatment with the hydroalcoholic solutions, with quantitative and qualitative differences between the groups. These results suggest that the hepatoxicity of ethanol in alcoholic beverages is enhanced by interaction with its congeners and acetaldehyde; they also suggest that alcoholic beverages are not equivalent in their potential to cause liver damage.

Alcoholic Beverages↗
PubMed1993

Phacolytic glaucoma and lens-induced uveitis.

The pathogenesis of lens-induced uveitis and phacolytic glaucoma is still not fully understood. The authors report a case of a 62-year-old white female, with bilateral lens dislocation into the vitreous, who presented clinical and pathological features of phacolytic glaucoma in the left eye. The ultrastructural study of aqueous and vitreous aspirates showed lenticular fragments and macrophages with lipofuscin granules and phagocytic vacuoles containing lens proteins. Immunocytochemistry revealed foamy macrophages immunoreactive for CD68 and HLA-DR. One year later the right eye disclosed a mild anterior granulomatous uveitis with corneal mutton-fat keratic precipitates that remained unchanged in the course of sixteen months follow-up without further treatment. These findings corroborate the possibility that, besides their mechanical and inflammatory roles in the impairment of the outflow system of the (exciting) left eye, phacolytic macrophages might also have been involved in the afferent phase of the mild chronic uveitis of the (fellow) right eye.

Aqueous Humor↗
PubMed1993

[Interaction of the contents of alcoholic beverages in the promotion of liver damage].

The adverse effects of the exposure of the liver to the interaction of ethanol with its congeners and acetaldehyde, coexisting in the contents of alcoholic beverages, have been little studied. Twenty four male Wistar rats were divided into four groups. Two groups (SH/DA; SH/FA) were submitted to daily treatment with synthetic hydroalcoholic solutions containing ethanol, methanol, higher alcohols and acetaldehyde in the same proportions as those found in most common distilled and fermented alcoholic beverages; the third group (SH/EA) was treated with a hydroalcoholic solution of ethanol; the fourth group served as control and received an equivalent volume of an isocaloric solution of dextrose. All the animals were killed at the end of the 9th week of the experiment. The ratio between the liver weight and body weight was found to be lower in the treated animals than in the control group. The histology of the liver was altered in the three groups which were submitted to treatment with the hydroalcoholic solutions, with quantitative and qualitative differences between the groups. These results suggest that the hepatoxicity of ethanol in alcoholic beverages is enhanced by interaction with its congeners and acetaldehyde; they also suggest that alcoholic beverages are not equivalent in their potential to cause liver damage.

Acetaldehyde↗
PubMed1992

Cis and trans regulatory elements required for regulation of the CHO1 gene of Saccharomyces cerevisiae.

A 34 base-pair (bp) fragment spanning sequences -154 to -120 of the promoter of the CHO1 gene (structural gene for phosphatidylserine synthase) from the yeast Saccharomyces cerevisiae has been shown to place transcription of a promoter-less Escherichia coli lacZ gene under control of the phospholipid precursors inositol and choline. Furthermore, in deletion experiments the CHO1 UASINO was localized to sequences between -151 and -123 of the CHO1 promoter. A nine bp sequence was identified in the promoter region of the CHO1 gene that shares an eight out of nine bp match with a sequence (consensus 5' ATGTGAAAT 3') that is repeated a total of 23 times upstream from several coregulated phospholipid biosynthetic genes. This sequence is contained within the -151 to -123 region to which the CHO1 UAS has been localized. The nine bp repeated element is believed to be involved in the control of phospholipid biosynthetic gene transcription in response to changing levels of inositol and choline in the growth medium. This control has been shown to require activities encoded by the products of the three regulatory genes: INO2, INO4, and OPI1. A mutation in any of these regulatory genes results in aberrant CHO1-lacZ gene regulation, and affects regulation of the construct containing the 34 bp (-154 to -120) CHO1 fragment demonstrating that the regulatory signal generated by these genes interacts with the 5' end of the CHO1 gene.

Amino Acid Sequence↗