RESUMEN
During the last 20 years, the mechanisms involved in the stimulation of defense against pathogens, and growth triggered by chitosan-, alginate- and carrageenan-derived oligosaccharides have been studied in plants. Oligo-chitosan stimulate protection against pathogens by activation of salicylic acid (SA) or jasmonic acid/ethylene (JA/ET)-dependent pathways, protection against abiotic stress through abscisic acid (ABA)-dependent pathway, and growth by increasing photosynthesis, auxin and gibberellin content, C and N assimilation, and synthesis of secondary metabolites with antipathogenic and medicinal properties. Oligo-alginates stimulate protection against pathogens through SA-dependent pathway, abiotic stress via ABA-dependent pathway, and growth by increasing photosynthesis, auxin and gibberellins contents, C and N assimilation, and synthesis of secondary metabolites with antipathogenic and medicinal properties. Oligo-carrageenan increased protection against pathogens through JA/ET, SA- and Target of Rapamycin (TOR)-dependent pathways, and growth by activation of TOR-dependent pathway leading to an increase in expression of genes involved in photosynthesis, C, N, S assimilation, and enzymes that synthesize phenolic compounds and terpenes having antipathogenic activities. Thus, the latter oligosaccharides induce similar biological effects, but through different signaling pathways in plants.
Asunto(s)
Alginatos/química , Carragenina/química , Quitosano/química , Oligosacáridos/farmacología , Plantas/efectos de los fármacos , Oligosacáridos/química , Plantas/metabolismo , Estrés Fisiológico/efectos de los fármacosRESUMEN
OBJECTIVE: Our purpose was to develop a specific polymerase chain reaction detection method for 16 micro-organisms in amniotic fluid and to correlate its performance with bacterial cultures and preterm delivery occurrence. STUDY DESIGN: The study group was made up of 50 patients with preterm labor and intact membranes. The control group consisted of 23 patients not in labor and undergoing amniocentesis for either karyotype or lung maturity studies. Polymerase chain reaction and bacterial cultures were assayed in amniotic fluid of all patients. Results were correlated with pregnancy outcome. RESULTS: Polymerase chain reaction identified micro-organisms in 23 cases in the study group (46%), whereas cultures identified only 6 (12%). All control samples were negative for polymerase chain reaction and cultures. The sensitivity of polymerase chain reaction and cultures for the identification of patients delivering before 34 weeks' gestation was 64% and 18%, respectively. CONCLUSION: A polymerase chain reaction gene amplification method was developed to identify 16 micro-organisms in amniotic fluid. Compared with bacterial cultures, polymerase chain reaction amplification in amniotic fluid appears to be more sensitive in identifying patients delivering prematurely.
Asunto(s)
Líquido Amniótico/microbiología , Parto Obstétrico , Trabajo de Parto Prematuro/epidemiología , Reacción en Cadena de la Polimerasa , Adolescente , Adulto , Infecciones Bacterianas/epidemiología , Femenino , Humanos , Incidencia , Recién Nacido , Enfermedades del Recién Nacido/epidemiología , Morbilidad , EmbarazoRESUMEN
The intronic mat-r ORF encodes a protein with significant homology to retroviral reverse transcriptases. Here, we describe the nucleotide sequence of potato mat-r and study the editing status of mat-r transcripts in two systems, potato and wheat, where the mat-r ORF is part of the trans-introns but in two different configurations relative to nad1 exons d and e. In potato and wheat, 13 and 15 C-to-U transitions respectively were observed. Most transcripts were partially edited, but potato transcripts were edited more efficiently than wheat transcripts. As in functional mitochondrial genes, RNA editing increased the similarity between plant mat-r proteins and their homologous non-plant counterparts. Interestingly, editing of mat-r was clustered in the reverse-transcriptase (RT) and the maturase (X) domains, two well defined regions having known functions in other systems. These results, together with the integrity and sequence conservation of mat-r, strongly suggest that the encoded protein plays a functional role in plant mitochondria.
Asunto(s)
Endorribonucleasas/genética , Mitocondrias/genética , Nucleotidiltransferasas/genética , Proteínas de Plantas/genética , Edición de ARN/genética , Solanum tuberosum/genética , Triticum/genética , Secuencia de Aminoácidos , Secuencia de Bases , Sitios de Unión/genética , Sitios de Unión/fisiología , Citidina/genética , Citidina/metabolismo , Citosina/metabolismo , ADN Mitocondrial/análisis , ADN Mitocondrial/genética , ADN de Plantas/análisis , ADN de Plantas/genética , Endorribonucleasas/aislamiento & purificación , Genes de Plantas/genética , Mitocondrias/química , Datos de Secuencia Molecular , Nucleotidiltransferasas/aislamiento & purificación , ARN/genética , ARN/metabolismo , ARN Mitocondrial , ADN Polimerasa Dirigida por ARN/genética , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Solanum tuberosum/química , Transcripción Genética/genética , Triticum/química , Uracilo/metabolismo , Uridina/genética , Uridina/metabolismoRESUMEN
Recent demonstrations of no changes in hypothalamic gonadotropin releasing hormone (GnRH) gene expression and GnRH levels detected at the pituitary gland in diestrous and lactating rats, indicate that lactational hypogonadotropism in this species is not associated with inhibition of hypothalamic GnRH synthesis and secretion. Hypothalamic galanin potentiates GnRH effects on luteinizing hormone (LH) secretion in male and cycling rats. To explore the interaction between GnRH and galanin during lactation, we studied in vitro the effects of pulsatile stimulation with those peptides upon LH synthesis and secretion from rat pituitaries on diestrous 1 or day 10 of lactation. Hemipituitaries were separately incubated in 1 ml Dulbecco's Minimal Essential Medium supplemented with 1% penicillin-streptomycin and fetal calf serum, at 37 degrees C in 5% CO2-air. The hemipituitaries were stimulated during 12 h with hourly pulses, 6 min each, of (a) gonadotropin releasing hormone (GnRH 25 ng/pulse), (b) rat galanin (600 ng/pulse), (c) GnRH plus galanin, or (d) saline. Medium was collected before each pulse to determine LH by radioimmunoassay. After the 12 h pulsatile regime total RNA was extracted and both actin and beta-LH mRNA were determined by reverse transcriptase polymerase chain reaction. There was a significant stimulation of LH secretion by GnRH (ANOVA, p < 0.001) without significant differences between diestrous and lactation pituitaries. Galanin alone did not modify LH secretion but it potentiated the effect of GnRH upon pituitaries from diestrous (p = 0.036) but not lactating rats. Neither peptide alone or its combination modified pituitary beta-LH mRNA levels. Results show that galanin regulates differently the secretion and synthesis of LH at the pituitary level. The disappearance of galanin-induced potentiation of GnRH effects upon LH secretion during lactation might contribute to the hypogonadotropism of lactation in the rat.
Asunto(s)
Animales Lactantes/fisiología , Galanina/fisiología , Hormona Liberadora de Gonadotropina/fisiología , Hormona Luteinizante/metabolismo , Animales , Diestro , Femenino , Técnicas In Vitro , Hormona Luteinizante/biosíntesis , Hipófisis , Ratas , Ratas Sprague-DawleyRESUMEN
The L5 ribosomal protein gene (rpl5) and a S14 ribosomal protein pseudogene were identified by sequence analysis in the potato mitochondrial genome. The two genes are separated by one nucleotide and are found upstream of the apocytochrome b gene (cob), an arrangement conserved also in Arabidopsis and Brassica. The rpl5 gene has an intact open reading frame while the rps14 locus is disrupted by a five nucleotide duplication that introduces a frameshift in the reading frame. Editing of rpl5 and pseudorps14 cotranscripts has been studied by cDNA sequence analysis. Eight C residues are edited into U in the rpl5 coding region, resulting in eight amino acid changes that increase the homology between potato and other RPL5 polypeptides. Interestingly, the rps14 pseudogene sequence is not edited at any nucleotide position.
Asunto(s)
Genes de Plantas/genética , Seudogenes/genética , Proteínas Ribosómicas/genética , Solanum tuberosum/genética , Secuencia de Aminoácidos , Apoproteínas/genética , Secuencia de Bases , Grupo Citocromo b/genética , Citocromos b , ADN Mitocondrial/genética , ADN de Plantas/genética , Mitocondrias , Datos de Secuencia Molecular , Sistemas de Lectura Abierta/genética , ARN/análisis , Edición de ARN/fisiología , ARN Mitocondrial , ARN de Planta/análisis , Mapeo Restrictivo , Análisis de Secuencia de ADNRESUMEN
A reverse transcriptase activity has been detected in potato mitochondria using special RNAs as templates: a bacterial RNA coding for neomycin phosphotransferase (neo pa RNA) and a Neurospora crassa mitochondrial RNA (184 nt RNA). Surprisingly, no exogenous primer addition was required. These RNA templates share a primary and secondary structure similar to the T psi CG loop of tRNAs that could constitute the recognition site for the enzyme. Reverse transcriptase activity was inhibited by ddTTP, ethidium bromide and aphidicolin, while potato mitochondrial DNA polymerase was not inhibited by aphidicolin indicating that these activities correspond to distinct enzymes. A conserved sequence of reverse transcriptases was detected in potato mitochondrial DNA suggesting that this enzyme could be mitochondrially encoded.
Asunto(s)
Mitocondrias/enzimología , ADN Polimerasa Dirigida por ARN/metabolismo , Solanum tuberosum/enzimología , Secuencia de Bases , ADN Complementario/genética , ADN Mitocondrial/genética , Genes de Plantas , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Oligonucleótidos/química , ARN/ultraestructura , ARN Mitocondrial , ADN Polimerasa Dirigida por ARN/genética , Inhibidores de la Transcriptasa Inversa/farmacologíaRESUMEN
The structure and expression of the potato mitochondrial gene rps10, encoding ribosomal protein S10, has been characterized. The RPS10 polypeptide of 129 amino acids is encoded by two exons of 307 bp and 80 bp respectively, which are separated by a 774-bp class-II intron. Editing of the complete rps10 coding region was studied by sequence analysis of spliced cDNAs. Four C residues are edited into U, resulting in the creation of a putative translational initiation codon, a new stop codon which eliminated ten carboxy-terminal residues, and two additional amino-acid alterations. All these changes increase the similarity between the potato and liverwort polypeptides. One additional C-to-U RNA editing event, observed in the intron sequence of unspliced cDNAs, improves the stability of the secondary structure in stem I (i) of domain I and may thus be required for the splicing reaction. All spliced cDNAs, and most unspliced cDNAs, were completely edited, suggesting that editing is an early step of rps10 mRNA processing and precedes splicing. Earlier work on potato rps10 (Zanlungo et al. 1994) is now known to comprise only a partial analysis of the gene, since the short downstream exon was not identified.
Asunto(s)
Proteínas de Plantas/genética , Edición de ARN/genética , Empalme del ARN/genética , Proteínas Ribosómicas/genética , Solanum tuberosum/genética , Solanum tuberosum/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Codón/genética , Cartilla de ADN/genética , ADN Complementario/genética , ADN Mitocondrial/genética , ADN de Plantas/genética , Exones , Genes de Plantas , Intrones , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , ARN de Planta/química , ARN de Planta/genética , ARN de Planta/metabolismo , Homología de Secuencia de Aminoácido , Transcripción GenéticaRESUMEN
The S10 ribosomal protein gene (rps10), which has not been previously reported in any angiosperm mitochondrial genome, was identified by sequence analysis in the potato mitochondrial DNA. This gene is found downstream of a truncated non-functional apocytochrome b (cob) pseudogene, and is expressed as multiple transcripts ranging in size from 0.8 to 5.0 kb. Southern hybridization analysis indicates that rps10-homologous sequences are not present in the wheat mitochondrial genome. Sequence analysis of a single-copy region of the pea mitochondrial genome located upstream of cox1 [11] shows that a non-functional rps10 pseudogene is present in this species. These results suggest that the functional genes coding for wheat and pea mitochondrial RPS10 polypeptides have been translocated to the nucleus.
Asunto(s)
ADN Mitocondrial/metabolismo , Genes de Plantas , Seudogenes , Proteínas Ribosómicas/biosíntesis , Solanum tuberosum/genética , Secuencia de Aminoácidos , Secuencia de Bases , Northern Blotting , Escherichia coli/metabolismo , Mitocondrias/metabolismo , Datos de Secuencia Molecular , Plantas/metabolismo , Mapeo Restrictivo , Proteínas Ribosómicas/genética , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido Nucleico , Solanum tuberosum/metabolismo , Transcripción GenéticaRESUMEN
RPC53 has previously been shown to encode an essential subunit required for tRNA gene transcription by RNA polymerase C in vivo (Mann, C., Micouin, J.-Y., Chiannilkulchai, N., Treich, I., Buhler, J.-M., and Sentenac, A. (1992) Mol. Cell. Biol. 12, in press). In this paper, we have determined that an unusual rho+ lethality associated with the rpc53::HIS3-1 disruption mutation is due to the inadvertent formation of a Pet56-C53 fusion protein. This fusion protein is missorted to mitochondria, thereby reducing the quantity of the C53 subunit available for RNA polymerase C assembly. We show that the carboxyl-terminal region of C53 contains the essential functional domain of the subunit and that a mutant RNA polymerase containing only this domain is thermolabile for its function in vivo and in vitro. The thermolability of the carboxyl-terminal C53 domain is suppressed by five different genes on multicopy plasmids, including RPC160, encoding the largest subunit of RNA polymerase C and SSD1/SRK1, which has been implicated in the activity of protein phosphatases.
Asunto(s)
Genes Fúngicos , Mitocondrias/enzimología , ARN Polimerasa III/genética , ARN Polimerasa III/metabolismo , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Transcripción Genética , Alelos , Secuencia de Aminoácidos , Secuencia de Bases , ADN de Hongos/genética , ADN de Hongos/metabolismo , Estabilidad de Enzimas , Genes Letales , Prueba de Complementación Genética , Biblioteca Genómica , Cinética , Sustancias Macromoleculares , Datos de Secuencia Molecular , Mutagénesis , Oligodesoxirribonucleótidos , Plásmidos , Reacción en Cadena de la Polimerasa/métodos , ARN Polimerasa III/aislamiento & purificación , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Mapeo Restrictivo , Factor Rho/genética , Eliminación de SecuenciaRESUMEN
Unlike the majority of genes encoding small nuclear RNAs, which are transcribed by RNA polymerase B, the U6 gene contains features found in both class B and class C genes, indicating the involvement of a combination of transcription factors normally specific to each class of genes. We present direct genetic and biochemical evidence that the U6 gene of Saccharomyces cerevisiae is transcribed by RNA polymerase C in vivo as well as in vitro. A mutant strain with a temperature-sensitive defect in the large subunit of RNA polymerase C that results in defective transcription of tRNA and 5S RNA genes shows a corresponding defect in U6 RNA levels. Also, purified RNA polymerase C transcribes the U6 gene when supplemented with partially purified TFIIIB. The other class C transcription factors, TFIIIA and Tau (TFIIIC), are not required in this system.
Asunto(s)
ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasa III/metabolismo , ARN Nuclear Pequeño/genética , Saccharomyces cerevisiae/genética , Transcripción Genética , Secuencia de Bases , Datos de Secuencia Molecular , Mutación , Hibridación de Ácido Nucleico , ARN Ribosómico 5S/genética , ARN de Transferencia/genética , Mapeo Restrictivo , Endonucleasas Específicas del ADN y ARN con un Solo Filamento , Factor de Transcripción TFIIIB , Factores de Transcripción/farmacologíaRESUMEN
A 18.4-kb fragment of the yeast genome containing the gene of the largest subunit of RNA polymerase C (RPC160) was cloned by hybridization to a previously isolated fragment of that gene. RPC160 maps on chromosome XV, tightly linked but not allelic to the essential gene TSM8740. Temperature sensitive (ts) mutant alleles were constructed by in vitro mutagenesis with NaHSO3 and substituted for the wild-type allele on the chromosome. Four of them were unambiguously identified as rpc160 mutants by failure to complement a fully defective mutation rpc160::URA3. The faithful transcription of a yeast tRNA gene by mutant cell-free extracts is strongly reduced as compared to wild-type. In vivo, the rpc160 mutations specifically affect the synthesis of tRNA in a temperature sensitive way, with comparatively little effect on the synthesis of 5S rRNA and no effect on 5.8S rRNA. An unlinked mutation (pcil-3) suppresses the temperature sensitive phenotype of the rpc160-41 mutation.
Asunto(s)
ARN Polimerasas Dirigidas por ADN/genética , Genes Fúngicos , Genes , Mutación , ARN Polimerasa III/genética , Saccharomyces cerevisiae/genética , Mapeo Cromosómico , Clonación Molecular , Enzimas de Restricción del ADN , Genotipo , Sustancias Macromoleculares , Saccharomyces cerevisiae/enzimología , Transcripción GenéticaRESUMEN
Several cloned members of the yeast tRNA(Phe) gene family were transcribed in vitro using a HeLa extract and a yeast extract. The optimum DNA concentration was determined and kinetic experiments were performed for each clone to compare transcription levels. Both extract systems were able to splice the intervening sequence, but only the yeast extract produced the mature product. Some genes were not transcribed with the homologous system while they were transcribed with the HeLa extract, suggesting a control mechanism that is not operating in the heterologous system. Competition experiments demonstrated that the intragenic promoters of the inactive genes were able to bind transcription factor(s), but not as efficiently as active genes. This binding was not so strong when using linear DNA and was dependent on the presence of the 3' intragenic control region. DNA sequencing and computer analysis indicated the presence of short conserved sequences upstream from the genes. These sequences, which are not related to the intragenic promoters, are direct repeats of part of the 3' coding region in those genes that are transcribed in the homologous system. The relevance of these sequences on homologous transcription in vitro remains to be established.
Asunto(s)
ARN de Hongos/genética , ARN de Transferencia Aminoácido-Específico/genética , ARN de Transferencia de Fenilalanina/genética , Saccharomyces cerevisiae/genética , Secuencia de Bases , ADN Superhelicoidal/fisiología , Genes Fúngicos , Células HeLa , Técnicas In Vitro , Cinética , Datos de Secuencia Molecular , Familia de Multigenes , Conformación de Ácido Nucleico , Regiones Promotoras Genéticas , Factores de Transcripción/fisiología , Transcripción GenéticaRESUMEN
Transcription of eukaryotic transfer RNA genes involves, as a primary event, the stable binding of a protein factor to the intragenic promoter. The internal control region is composed of two non-contiguous conserved sequence elements, the A and B blocks. These are variably spaced depending on the genes. tau, a large transcription factor purified from yeast cells, interacts with these two control elements as shown by DNase I footprinting, exonuclease digestion, dimethyl sulphate protection experiments and by analysis of point mutations. Here we used a limited proteolysis treatment to obtain a smaller form of tau with drastically altered DNA binding properties. A protease-resistant domain interacts solely with the B block region of tRNA genes.
Asunto(s)
Proteínas de Unión al ADN/metabolismo , ADN/metabolismo , Péptido Hidrolasas/farmacología , Factores de Transcripción/metabolismo , Sitios de Unión , ADN de Cadena Simple/farmacología , Regulación de la Expresión Génica , ARN de Transferencia/genética , Levaduras/genéticaRESUMEN
PIP: The extent and consequences of exclusion of low income strata from maternal and child health programs in Chile are analyzed using available data. Infant mortality has been shown by several studies to be closely associated with socioeconomic status in Chile. Babies of illiterate mothers showed the highest rate of mortality and the least improvement in rate between 1972-78. The effect of socioeconomic status on the mortality rate of infants in greatly influenced by birth weight; low birth weight infants of low income groups suffer significantly higher mortality than among higher income groups. Several national studies in Chile demonstrated a relationship between infant malnutrition and health program coverage. Infant malnutrition is greatest in groups benefiting least from health care. Based on the fact that 90.5% of births in 1980 were professionally attended, it is estimated that 9.5% of the low income population lacks access to health care. A recent survey showed that 9.9% of the population under 6 years, some 105,848 children, was not covered by the National Complementary Feeding Program. Another study showed that 12.3% of mothers had no prenatal medical attention prior to their most recent birth; mothers with little or no education, living in rural areas, and of high parity were most likely not to have received medical attention. Factors responsible for lack of access to health and nutrition programs appeared to include unsatisfactory relationships with the health workers, poor acceptability of foods offered, excessive distance and waiting times, and lack of interest or motivation on the part of the mothers.^ieng