PubMed Health⌕ Search

Biomedical subjects

V Rodrigues

Publications and source records attributed to V Rodrigues.

At least 55 records · Page 3Linked to original sources
PubMed1995

malvolio, the Drosophila homologue of mouse NRAMP-1 (Bcg), is expressed in macrophages and in the nervous system and is required for normal taste behaviour.

We report the sequence, expression pattern and mutant phenotype of malvolio (mvl), the Drosophila homologue of mammalian natural resistance-associated macrophage proteins (NRAMPs). In the mouse, this novel transporter is encoded by Bcg, a dominant gene that confers natural resistance to intracellular parasites. mvl was identified in a screen for mutants that affect taste behaviour. We show that loss-of-function as well as insertional mutants in mvl display defects in taste behaviour with no alterations in the physiology of the sensory neurons. Activity of the reporter enzyme beta-galactosidase, that reflects the expression pattern of mvl, is seen in mature sensory neurons and in macrophages. The conceptual translation of the mvl cDNA shows a striking similarity (65% identity) with human NRAMP with almost complete identity in a conserved consensus motif found in a number of ATP-coupled transporters. Based on its phenotype and expression pattern as well as its structural similarities to NRAMPs and a nitrate transporter in Aspergillus nidulans, we discuss a possible role for MVL in nitrite/nitrate transport and its implications.

Amino Acid Sequence↗
PubMed1995

Masquerade: a novel secreted serine protease-like molecule is required for somatic muscle attachment in the Drosophila embryo.

Diverse developmental processes, such as neuronal growth cone migration and cell shape changes, are mediated by the interactions of cells with the extracellular matrix. We describe here a secreted molecule encoded by the Drosophila masquerade (mas) gene. Total loss of mas function causes defective muscle attachment. This mutant phenotype suggests that mas normally acts to stabilize cell-matrix interaction and represents a novel functional and limiting component in the adhesion process. mas encodes a 1047-amino-acid preproprotein that is further processed by proteolytic cleavage to generate two polypeptides. The carboxy-terminal polypeptide is highly similar to serine proteases and has an extracellular localization; however, it is unlikely to possess proteolytic activity, because the catalytic site serine has been substituted by a glycine residue. During embryonic development, the mas amino- and carboxy-terminal polypeptides are differentially localized. The mas carboxy-terminal polypeptide accumulates at all somatic muscle attachment sites, which corresponds well with the morphological defect seen in the mas mutants. Our findings demonstrate the involvement of an extracellular component in somatic muscle attachment. We propose that mas acts via its modified serine protease motif, either as a novel adhesion molecule and/or as a competitive antagonist of serine proteases, to stabilize muscle attachment.

Alleles↗
PubMed1995

Identification of a major T cell immunogen in the anti-schistosome response of adult residents in an area endemic for Schistosoma mansoni.

Vaccine-induced immunity to Schistosoma mansoni infection depends on the specific priming of certain T cell subsets and on the recall of this response by natural infections months or years after vaccine administration. Thus, those schistosome proteins that activate T cells in individuals stimulated by natural infections are potential candidate vaccine antigens. In the present study, we identified and purified one such T cell-stimulating antigen and evaluated its immunological properties in subjects living in an area endemic for Schistosoma mansoni. Chromatography fractions (gel filtration, followed by ion exchange chromatography) of soluble extracts of schistosomula were screened for their ability to stimulate schistosome-specific T cell clones derived from a subject sensitized by natural infection. A fraction stimulating most clones was identified and characterized. A few nanograms of this fraction, containing a major 9-10-kDa component, stimulated the T helper cells of most adults living in an endemic area of Brazil, and was able to trigger a strong cutaneous immediate hypersensitivity reaction. In contrast, children reacted weakly to this antigen preparation both in blastogenesis and in skin tests, although they mounted a significant reaction to crude larval antigen preparations. In conclusion, this work identifies a schistosomula antigen that induces a strong T cell response in adults sensitized by natural infections. This T cell response develops gradually in children and adolescents, is apparently not restricted by the HLA haplotypes common in the study area, and allows the production of parasite-specific IgE antibodies. Thus, this T cell response has some features of the immune response that is believed to protect chronically exposed humans from reinfection.

Adult↗
PubMed1995

Cellular events during development of the olfactory sense organs in Drosophila melanogaster.

The olfactory sensilla on the antenna of adult Drosophila melanogaster develop during the first 36 hr after pupariation, from their anlagen in the cephalic disc. We have used tissue-specific beta-galactosidase expression in the enhancer trap strain A101.IF3 and the monoclonal antibody 22C10 as sensory cell markers, as well as the lineage tracer 5-bromo-2'-deoxyuridine (BrdU), to describe this process. The development of an olfactory sensillum begins with the selection of a "founder cell" (FC). These cells are distinct in that they possess large apically located nuclei revealed by beta-galactosidase expression in A101.IF3. In the following 6 hr, a few cells neighboring the FC also start expressing beta-galactosidase and together comprise a group. Cells of this group, denoted a "presensillum-cluster" (PSC), undergo at least one round of replication and give rise to all of the cells of a sensillum. A subset of the cells within each PSC and, later, all the sensory neurons are recognized by MAb22C10. The antennae of the mutant lozenge3 (lz3) lack all basiconic and some trichoid sensilla. The mutation apparently affects early steps in sensillum development and many of the FCs fail to form. Those that are present, however, proceed to form mature olfactory sensilla. Therefore, we conclude that the selection of an FC is the first step in olfactory sense organ development. Our study reveals novel aspects of sensory development in Drosophila.

Animals↗
PubMed1995

Electrophoretical and histochemical characterization of Schistosoma mansoni phenol oxidases.

The phenol oxidase system, which is thought to play a central role in eggshell formation, was analyzed by means of electrophoretic and histochemical techniques. In contrast to current beliefs, our data show that males also express the phenol oxidase activity. The analysis of the electrophoretic pattern from males and females shows differences: adult males present a major band and a faint band, migrating slightly below. Adult females express a more complex pattern composed of four bands. Histochemical studies revealed that female phenol oxidase is concentrated in the vitelline cells, is inhibited by DDC, and this inhibition is correlated with disruption of female egg production. The present studies, in agreement with other reports, reveal that female phenol oxidase may be involved in sclerotization of the S. mansoni eggshell.

Animals↗
PubMed1995

Distinct mechanisms of action of the Lozenge locus in Drosophila eye and antennal development are suggested by the analysis of dominant enhancers.

The development of the olfactory sense organs on the antenna of the fruit fly Drosophila utilises mechanisms distinct from those used in the rest of the adult peripheral nervous system. Lozenge (lz) is the only locus hither-to identified as required for the development of antennal sense organs. In addition to effects on the antenna, mutations in lz also affect the development of the eye and maxillary palp. We have used the readily-scored eye-phenotype in a temperature sensitive lz allele to screen for dominant modifiers of phenotypes at this locus. We analyse the phenotypes of both intragenic and extragenic modifiers. Our results reinforce the view from developmental studies that lz functions in eye and antennal development in distinct ways.

Alleles↗
PubMed1994

Epidemiology of hepatitis C in central Portugal. Prevalence of anti-HCV in the population of the Coimbra District.

Anti-hepatitis C virus antibody (anti-HCV) screening was performed in a sample of the adult population of the Coimbra District. 657 persons were included (267 male and 390 female, mean age of 42.7 + 13.1 years), aleatorily chosen from four characteristic regions. Anti-HCV was detected using an ELISA-2 test and all positive sera were also tested with RIBA-2. General prevalence of anti-HCV was 0.46%. All positive patients live in urban areas and presented risk factors for HCV infection. Anti-HCV was found in 33.3% of intravenous drug abusers, in 1.8% of transfused individuals, in 1.33% of alcoholics (higher than 80 g/d alcohol ingestion), in 1% of cases with history of surgical operations, and in 0.65% of persons who lived in risk regions for hepatitis B. We conclude that anti-HCV prevalence is low in our region. We think it is important to perform other studies on larger samples of general population and to study risk groups.

Adult↗
PubMed1993

Development of the taste bristles on the labellum of Drosophila melanogaster.

The taste bristles of the adult labellum develop from the labial discs within the first 30 hr of pupation. The neuron-specific antibody Mab22C10 and the tissue-specific beta-galactosidase activity in the A37 strain were used as cell markers for the developing sensilla. These experiments revealed that the sensory progenitors of all the labellar bristles are specified in three waves occurring 0, 6, and 16 hr after pupation. The incorporation of the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) into the cells of the developing proboscis further supports the temporal pattern of the sensillum specification. Mitotic activity in the bristles specified in the first wave is completed before the next wave is initiated. The eight cells that constitute a single bristle share a common lineage. The trichogen and tormogen cells are siblings from a single progenitor and the thecogen and the five neurons share a common ancestry. Our results provide a basis for the identification of molecules that specify the development of the polyinnervated bristles of the adult and the specification of neurons with different stimulus specificities.

Age Factors↗
PubMed1993

The Drosophila homolog of the human transcription factor TEF-1, scalloped, is essential for normal taste behavior.

The scalloped (sd) locus of Drosophila melanogaster encodes a protein with a novel DNA binding domain bearing a high degree of similarity to the human transcription factor TEF-1 (Campbell et al., 1992). We demonstrate that sd mutants show defects in response to a number of taste stimuli. Higher stimulus concentrations are required to elicit behavioral responses from mutant larvae and adult flies. The electrophysiological responses of the peripheral taste neurons in the labellum were found to be normal, suggesting that an inability to detect stimuli is not the cause of the mutant phenotype. The range of mutant responses of sd alleles to salt and sugar stimuli define a functional requirement for the gene in the nervous system and provide an assay for the genetic and molecular analysis of this role.

Alleles↗
PubMed1993

[Hepatitis C epidemiology in the central area of Portugal. Prevalence of anti-HCV in the population of the district of Coimbra].

Anti-hepatitis C virus antibody (anti-HCV) screening was performed in a sample of the adult population of the Coimbra District. 657 persons were included (267 male and 390 female, mean age of 42.7 +/- 13.1 years), aleatorily chosen from four characteristic councils. Anti-HCV was detected using an ELISA-2 test and all positive sera were also tested with RIBA-2. General prevalence of anti-HCV was 0.46%. All positive patients live in urban areas and presented risk factors for HCV infection. Anti-HCV was found in 33.3% of intravenous drug abusers, in 1.8% of transfused individuals, in 1.33% of alcoholics (higher than 80 g/d alcohol ingestion), in 1% of cases with history of surgical operations, and in 0.65% of persons who lived in risk regions for hepatitis B. We conclude that anti-HCV prevalence is low in our region. We think it is important to perform other studies in larger samples of general population and to study risk groups.

Adult↗
PubMed1992

The east gene of Drosophila melanogaster is expressed in the developing embryonic nervous system and is required for normal olfactory and gustatory responses of the adult.

Drosophila melanogaster larvae and adults respond to a wide range of chemosensory stimuli. We describe the genetics and developmental expression of the east gene, mutations which result in adult-specific chemosensory defects. The original isolate of east is semidominant for the behavioral phenotype. Several mutations have been generated, some of which are recessive lethals and others that are viable alleles that show a recessive, adult-specific, chemosensory defect. No larval chemosensory defects were observed. The east gene is expressed in the neurogenic region at the time of neuroblast segregation and in cells in the peripheral and central nervous system. Our results suggest that east+ expression in the nervous system is required for a normal adult chemosensory response and both increases and decreases in levels of the gene product result in a mutant phenotype.

Alleles↗
PubMed1992

The scalloped gene encodes a novel, evolutionarily conserved transcription factor required for sensory organ differentiation in Drosophila.

The scalloped (sd) gene of Drosophila melanogaster was initially characterized by mutants affecting structures on the wing of the adult fly. The sequence of a cDNA clone of the gene reveals a predicted protein sequence homologous to that of a human transcriptional enhancer factor, TEF-1 (68% identity). The homology includes a sequence motif, the TEA domain, that was shown previously to be a DNA-binding domain of TEF-1. An sd enhancer trap strain expresses the reporter gene in a subset of neuroblasts in the central nervous system and in the peripheral sense organs of the embryo. The reporter gene is later expressed in specific regions of the imaginal discs, including regions of the wing disc destined to become structures defective in viable sd mutants. Later still, expression in the adult brain is restricted to subsets of cells, some in regions involved in the processing of gustatory information. These observations indicate that the sd gene encodes a transcription factor that functions in the regulation of cell-specific gene expression during Drosophila development, particularly in the differentiation of the nervous system.

Amino Acid Sequence↗
PubMed1991

Closely linked lesions in a region of the X chromosome affect central and peripheral steps in gustatory processing in Drosophila.

We have analyzed a set of closely linked mutations on the X chromosome of Drosophila that lead to defects in gustatory behavior. The mutations map to a small region of the X chromosome between 10E1-4. Two distinct complementation groups, gustB and gustD, map to the ends of this region. These groups show complex complementation patterns with the mutations gustC and GT-1, which also map to this region. We describe the behavioral and electrophysiological properties of the mutants. These mutations affect peripheral receptor properties as well as more central processing steps in the gustatory pathway.

Animals↗
PubMed1991

The shaker and shaking-B genes specify elements in the processing of gustatory information in Drosophila melanogaster.

Mutations that affect the physiological properties of neurones or the development of neuronal circuits are likely to have profound effects on sensory and motor pathways. We have examined the effects of mutations in two loci--the Shaker complex and shaking-B-on the taste pathway of Drosophila melanogaster Meigen at the behavioural and electrophysiological levels. The Shaker locus encodes a variety of A-type potassium channels that are likely to be tissue- and stage-specific. Flies containing the different Shaker alleles examined exhibit a variety of defects in their gustatory responses to sucrose, NaCl and KCl. The firing patterns of the labellar chemosensory neurones in response to these stimuli are normal. This suggests that the channels encoded by the Shaker locus are probably not involved in taste transduction, but affect central gustatory circuits. The shaking-B locus affects neuronal connectivity, though its molecular nature is unknown. Mutants at this locus show increased thresholds for detection of sucrose and fructose and lack the attraction response to 0.1 mol l-1 sodium chloride that is exhibited by the wild-type fly.

Action Potentials↗
PubMed1990

Genetics of olfactory behavior in Drosophila melanogaster.

We have used a behavioral genetic approach to identify six X-linked loci which specify olfaction in Drosophila melanogaster. Mutations in five of these genes lead to partial anosmias affecting responses either to aldehydes (olfA, olfB, olfE and olfF) or to acetate esters (olfC). Only one of the mutants obtained in our screening (olfD) resulted in a insensitivity to several different odorants. olfA, olfE and olfC map close together in a small region of the chromosome between 7C and 7D. The alleles at the olfC locus fall into two phenotypic classes according to their responses to different acetate esters. The two groups of olfC alleles interact in-trans.

Animals↗
PubMed1990

Unusual molecular basis of Hb H disease in the Azores Islands, Portugal.

An Azorean family with Hb H disease (10% Hb H) was studied in order to elucidate its molecular basis. DNA studies on the patient only revealed a 4.2 kb "leftward" deletion of paternal origin which implies the co-inheritance of a nondeletional alpha-thalassemia determinant. Restriction endonuclease and oligonucleotide analysis allowed the exclusion of five point mutations: initiation codon (at both alpha 1- and alpha 2-globin genes), IVS-I donor splice junction pentanucleotide deletion, codon 125 CTG----CCG substitution, and Saudi Arabian polyadenylation signal mutation. These findings suggest that the molecular basis of this form of Hb H disease is probably different from those described previously.

Azores↗
PubMed1989

Predicted structure of a major Schistosoma mansoni eggshell protein.

The complete sequence for a major Schistosome mansoni eggshell protein gene has been determined from a genomic DNA fragment. The use of an open reading frame encoding a glycine-rich polypeptide was confirmed by in vitro translation of schistosome mRNA in the presence of [3H]glycine and comparison with the amino acid composition of purified, schistosome eggshells. Apart from the extraordinary abundance of glycine and tyrosine which are evenly distributed throughout the polypeptide chain, the most striking features of the deduced amino acid sequence are the presence of five well-conserved tandem repeats of 16-18 residues in the N-terminal region and the asymmetrical distribution of charged residues. Acidic residues (Asp) are confined to the N-terminal region, while basic residues (Lys, His), with the exception of a single histidine, are found in the C-terminal region. A model structure composed of short anti-parallel beta-strands is proposed, in which glycines and residues with small side chains lie within the strands and tyrosines and cysteines are arranged at the bends, where they would be available for cross-linking. Four such strands form one of the tandem repeats which are predicted in turn to form a stack of five closely packed beta-sheets, each of three strands and linked by the more variable fourth strand. The C-terminal region may form a similar but less compact structure. The ordered structure demonstrated by birefringence studies of the schistosome eggshell [Kusel, J. (1970) Parasitology 60, 79-88] could be formed by packing of the polypeptides such that the N-terminal domain contributes counter ions or cross-links to the C-terminal domain of adjacent molecules.

Amino Acid Sequence↗