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A Fraile

Publications and source records attributed to A Fraile.

At least 37 records · Page 2Linked to original sources
PubMed1997

Genetic exchange by recombination or reassortment is infrequent in natural populations of a tripartite RNA plant virus.

Two hundred seventeen field isolates of cucumber mosaic cucumovirus (CMV), sampled from 11 natural populations, were typed by RNase protection assay (RPA) using probes from the genomic RNAs of strains in subgroup I and in subgroup II of CMV strains. Most (85%) of the analyzed isolates belonged to subgroup I. For these subgroup I isolates, only two clearly different RPA patterns, A and B, were found for each of four probes representing RNA1, RNA2, and each of the two open reading frames in RNA3. On the basis of these RPA patterns for each probe, different haplotypes were defined. The frequency composition for these haplotypes differed for the various analyzed populations, with no correlation with place or year of sampling. This genetic structure corresponds to a metapopulation with local extinctions and recolonizations. Most subgroup I isolates (73%) belonged to haplotypes with RPA pattern A (type 1) or B (type 2) for all four probes. A significant fraction of subgroup I isolates (16%) gave evidence of mixed infections with these two main types, from which genetic exchange could occur. Genetic exchange by segment reassortment was seen to occur: the fraction of reassortant isolates was 4%, reassortment did not occur at random, and reassortants did not become established in the population. Thus, there is evidence of selection against reassortment between types 1 and 2 of subgroup I isolates. Aphid transmission experiments with plants doubly infected with type 1 and type 2 isolates gave further evidence that reassortment is selected against in CMV. Genetic exchange by recombination was detected for RNA3, for which two RPA probes were used. Recombinant isolates amounted to 7% and also did not become established in CMV populations. Sequence analyses of regions of RNA1, RNA2, and RNA3 showed that there are strong constraints to maintain the encoded sequence and also gave evidence that these constraints may have been different during divergence of types 1 and 2 and, later on, during diversification of these two types. Constraints to the evolution of encoded proteins may be related to selection against genetic exchange. Our data, thus, do not favor current hypotheses that explain the evolution of multipartite viral genomes to promote genetic exchange.

Genome, Viral↗
PubMed1997

Cytogenetic analysis of 280 patients with multiple myeloma and related disorders: primary breakpoints and clinical correlations.

Cytogenetic analysis of unstimulated short-term bone marrow cell cultures was performed on 280 patients with multiple myeloma and related disorders. In 65% of the cases, an additional short term B-cell stimulated culture was also examined. Chromosomally abnormal clones were found in 31% of the patients, 15% in Waldenström macroglobulinemia. 25% in monoclonal gammopathies, 33% in multiple myeloma, and 50% in plasma cell leukemia. Three primary chromosomal breakpoints were recurrently involved: 14q32, 16q22, and 22q11. Structural rearrangements of chromosome 1 were the most frequent (26% of the abnormal cases), but always as a secondary change. Rearrangements of band 14q32 were found in 22% of the abnormal cases. Among the multiple myeloma patients who showed an abnormal karyotype, 33 (46%) were hyperdiploid, most frequently, with 52-56 chromosomes, 29 patients (40%) were pseudodiploid, and the remaining 12 cases (14%) were hypodiploid. A highly significant relation was observed between the presence of an abnormal karyotype and the following clinical parameters: stage III (P = 0.0001), bone marrow plasma cell infiltration greater than 30% (P = 0.0001), presence of bone lesions (P = 0.0009), and beta 2-microglobulin levels greater than 4 mg/L (P = 0.0001).

Chromosome Aberrations↗
PubMed1996

Genetic diversity in tobacco mild green mosaic tobamovirus infecting the wild plant Nicotiana glauca.

The variability and genetic structure of tobacco mild green mosaic tobamovirus (TMGMV) was analyzed in a collection of isolates from Nicotiana glauca plants from Australia, California, Spain, and the east Mediterranean Basin. Ribonuclease protection was assayed on 53 isolates with six probes representing 85% of the TMGMV genome. Results showed that conserved domains in the TMGMV genome were different for each geographic population. The nucleotide sequence of two regions of the TMGMV genome was determined for 33 isolates. Nucleotide diversity values were smaller than those reported for other RNA genomes. For each population, genetic diversity was not related to the size of the area from which the isolates were collected, and was particularly small for Australia and Spain. Diversity values indicated population differentiation, which was largest between the less diverse Spanish and Australian populations. Nucleotide diversity values for nonsynonymous vs synonymous positions indicate moderate negative selection, except for the Spanish population for which it gave evidence of positive selection. On the whole, our data indicate that the low genetic diversity for this plant virus may be due to different factors such as positive and negative selection or the recent colonization of new areas or host plants. The intensity of these factors appears to be different for the various TMGMV geographical populations.

Biological Evolution↗
PubMed1995

Experimental evaluation of the ribonuclease protection assay method for the assessment of genetic heterogeneity in populations of RNA viruses.

The ribonuclease (RNase) protection assay (RPA) was evaluated as a method to estimate genetic distances among sequence variants of RNA viruses. The patterns of fragments generated, under different RPA conditions, by three sets of RNA sequence variants of known nucleotide sequence, were analyzed. Both the effectiveness of cleavage (i.e. the probability of cleavage in a certain heteroduplex) and its degree (i.e. in all the molecules in the assay or in a part of them) varied largely according to the nature of the mismatch. Probability and degree of cleavage were also dependent on distant sequence context effects. No correlation could be established between context and cleavage, so that the pattern of fragments in RPA cannot be unequivocally predicted from sequence information. Accordingly, nucleotide sequence differences between two sequence variants cannot be directly derived from RPA data. For all three sequence sets linear relationships were found between the number of non-shared fragments in the RPAs of two variants and their nucleotide sequence differences. Nevertheless, both linearity and the linear regression parameters varied largely according to the sequence set and according to RPA conditions, in a non-predictable way. Thus, under experimental conditions, RPA may not be as appropriate a method to estimate genetic distances between RNA sequences as simulation under an ideal model suggested. Possible ways to diminish the gap between the ideal model and the experimental procedure are proposed.

Cucumovirus↗
PubMed1994

Mapping helper virus functions for cucumber mosaic virus satellite RNA with pseudorecombinants derived from cucumber mosaic and tomato aspermy viruses.

P-TAV is a strain of tomato aspermy virus (TAV) able to efficiently support the systemic accumulation of some (i.e., B2-satRNA) but not of other (i.e., Ix-satRNA) strains of the satellite RNA (satRNA) of cucumber mosaic virus (CMV) in both tobacco and in tomato. As reported for V-TAV, the failure to support the systemic accumulation of Ix-satRNA seems to be due to an inefficient support of its systemic movement. Pseudorecombinants obtained by the exchange of RNAs 1 + 2 between P-TAV and Trk7-CMV, an efficient helper for the systemic accumulation of Ix-satRNA, were assayed for their ability to support the accumulation of CMV-satRNAs in tobacco plants and protoplasts. Pseudorecombinants having RNAs 1 + 2 from CMV supported the systemic movement and accumulation of CMV-satRNA as efficiently as CMV, whereas pseudorecombinants having RNAs 1 + 2 from TAV supported the CMV-satRNA very poorly. Thus, the ability to support the systemic movement and accumulation of CMV-satRNA is determined primarily by RNAs 1 + 2 and not by RNA 3, which is presumed to encode movement functions in the cucumoviruses and only has a minor, modulating effect on the systemic accumulation of satRNA. This suggests that for systemic movement CMV-satRNA has to interact with (the gene products of) RNAs 1 and/or 2 or that these viral RNAs compete with the satRNA for interaction with the coat or other movement proteins.

Cucumovirus↗
PubMed1993

Genetic variability and evolution of the satellite RNA of cucumber mosaic virus during natural epidemics.

The genetic structure of populations of cucumber mosaic virus (CMV) satellite RNA (satRNA) and its evolution were analyzed during the course of a CMV epidemic in tomatoes in eastern Spain. A total of 62 variants of CMV-satRNA from epidemic episodes in 1989, 1990, and 1991 were characterized by RNase protection assay (RPA); RPA patterns defined 60 haplotypes in the CMV-satRNA population. RPA of nine CMV-satRNAs of known sequences showed that numbers of nucleotide substitutions per site (dij) between different satRNAs can be estimated from RPA data. Thus, dij were estimated for any possible pair of field CMV-satRNA types, and nucleotide diversities within and between yearly subpopulations were calculated. Also, phylogenetic relationships among CMV-satRNAs were derived from RPA data (by parsimony) or from dij (by neighbor joining). From these analyses, a model for the evolution of CMV-satRNAs in field epidemics can be built. High genetic variability of CMV-satRNA results in very heterogeneous populations, even compared with those of other RNA genomes. The high diversity of the population is maintained through time by the continuous generation of variants by mutation, counterbalanced by negative selection; this results in a certain replacement of haplotypes from year to year. The sequential accumulation of mutations in CMV-satRNA leads to fast genetic divergence to reach what appears to be an upper permitted threshold.

Biological Evolution↗
PubMed1992

Differential interactions among strains of tomato aspermy virus and satellite RNAs of cucumber mosaic virus.

Tomato and tobacco plants were inoculated with either of two strains of tomato aspermy virus, 1-TAV or V-TAV, and each of six isolates of cucumber mosaic virus satellite RNA (CMV-satRNA), B1, B2, B3, Ix, or WL2. Ribonuclease protection assays, used to detect total satRNA and encapsidated satRNA, revealed that G-satRNA generated new satellite RNA not of the inoculated sequence. The other CMV-satRNAs were compared for their ability (1) to replicate, (2) to modulate symptoms, (3) to reduce TAV accumulation, and (4) to alter the extent of encapsidation of TAV genomic RNAs. The fraction of B2- and B3-satRNAs encapsidated was greater for 1-TAV than for V-TAV, although spread and accumulation of the satRNA were similar for both helper viruses. These results suggest that CMV-satRNA may spread in a nonencapsidated form. Accumulation of CMV-satRNA in systemically infected leaves was detected for all inoculum combinations except V-TAV and Ix-satRNA, for which the satellite RNA increased only in protoplasts and inoculated leaves of tobacco or tomato. In such inoculated leaves, Ix-satRNA was not detected in capsids. Thus the effectiveness of the TAV helpers of CMV-satRNAs may be controlled in at least some instances by the extent of satRNA spread or encapsidation rather than by the efficiency of satRNA replication. In contrast to infections initiated by inoculation of CMV and CMV-satRNA, inoculation of 1-TAV or V-TAV and CMV-satRNA did not alter the relative amounts of viral genomic RNAs encapsidated or result in accumulation of large amounts of double-stranded satRNA.

Helper Viruses↗
PubMed1992

Basic Endochitinases Are Major Proteins in Castanea sativa Cotyledons.

Basic endochitinases are abundant proteins in Castanea sativa Mill. cotyledons. Three basic chitinases were purified with molecular masses of 25, 26, and 32 kD (Ch1, Ch2, and Ch3) and with isoelectric points between 8 and 9.5. Antibodies raised against Ch1 cross-reacted with Ch2 and Ch3. However, Ch3 showed differences when compared with the other two enzymes, especially in its higher cysteine content. The size, amino acid composition, and N-terminal sequence of Ch1 indicate that it is a class II endochitinase and, therefore, has no cysteine-rich hevein domain. Ch1 inhibits the growth of the fungus Trichoderma viride. The biological role of these endochitinases is discussed.

Journal Article↗
PubMed1991

Secondary structure as a constraint on the evolution of a plant viral satellite RNA.

The genetic variability and evolution of the satellite RNA (satRNA) of cucumber mosaic virus (CMV) was analyzed. Twenty-five CMV-satRNAs compared clustered into three main groups, and no correlation was found between genetic proximity and other characteristics (pathogenicity, geographical origin) of the satRNAs. Values for the number of nucleotide substitutions per site between any two satRNAs suggest that divergence is checked by functional constraints. The analysis of mutations relative to an ancestral sequence, and the number of substitutions per site at first, second and third positions of codons in putative open reading frames, show that the variation of CMV-satRNAs does not follow a pattern typical of coding sequences, and indicates that preservation of the sequence of encoded products is not a constraint to evolution. On the other hand, when the observed variation was analyzed relative to a secondary structure model proposed for CMV-satRNAs, several lines of evidence indicated that the maintenance of the secondary structure is a constraint to evolution: the number of substitutions per site, the number of point insertions and deletions and the number of base substitutions that would disrupt base-pairing were significantly higher for unpaired than for base-paired positions. Also, compensatory mutations at base-paired positions occurred more frequently than expected from random. The results suggest that CMV-satRNAs are non-coding, functional RNAs whose biology would be determined by their direct interaction with components of the host and/or the helper virus.

Base Composition↗
PubMed1991

Host-associated selection of sequence variants from a satellite RNA of cucumber mosaic virus.

The sequence of lx-satRNA, a CMV-satRNA necrogenic for tomato that shows the unusual property of accumulating in cucumber and in squash to levels similar to those in tomato and in tobacco, was determined. When compared with the sequences of other necrogenic CMV-satRNAs that do not show this property, or with a sequence variant of lx-satRNA that retains it, the high accumulation of lx-satRNA in squash was correlated with the presence of two U/C transitions. The sequences of progeny lx-satRNA from passage experiments in tomato and in squash show that a sequence variant having a U at position 102 was selected in tomato and that the parent sequence with a C at 102 was consistently restored in squash when this U-variant was used as inoculum. The results from these passage experiments may be explained by the heterogeneous nature of RNA populations, built from a number of variants of a master sequence, and illustrate the validity of this concept for CMV-satRNAs. The data also show that a minor sequence change, such as the transition C/U at 102, may have a major effect on the fitness of sequence variants of CMV-satRNAs in different hosts, and this may be relevant to the evolution in nature of these small RNAs.

Base Sequence↗
PubMed1990

A classification of the tobamoviruses based on comparisons among their 126K proteins.

The products of partial proteolysis of the Mr 126,000 in vitro translation products of the RNA of eight tobamoviruses were separated by SDS-polyacrylamide gel electrophoresis. The peptide patterns obtained were compared using a computer program designed to establish phylogenetic relationships. The resulting most-parsimonious phylogenetic trees grouped the tobamoviruses into clusters I (tobacco mosaic virus, tomato mosaic virus, tobacco mild green mosaic virus, pepper mild mottle virus) and II (sunn-hemp mosaic virus, cucumber green mottle mosaic virus, kyuri green mottle mosaic virus), with ribgrass mosaic virus in an intermediate position. This clustering resembles that obtained when the coat proteins of these viruses are compared. If the tobamoviruses have arisen by divergence from an ancestral type, the results suggest that different parts of the genome have diverged similarly and that recombination has not played a major role in the evolution of the group.

Molecular Weight↗
PubMed1988

Effects of diamine oxidase inhibition during pregnancy in the rat.

The effects of inhibiting histamine catabolism, via oxidative deamination, on the course of pregnancy on rats and on their offspring were studied. Treatment with aminoguanidine, a potent inhibitor of diamine oxidase (EC 1.4.3.6), was performed during pregnancy, before histamine levels were spontaneously increased. Twenty-one day old fetuses from treated rats showed head, lung and liver hematomas with significant differences. Abnormalities of ossification were also recorded in bones of the cranial cavity, with different statistical significances. The results of the present experiment confirm that oxidative deamination is the main catabolic pathway for histamine in the rat. Organic and skeletal abnormalities found also suggest that diamine oxidase protects fetuses from histamine excesses attained during pregnancy.

Abnormalities, Drug-Induced↗
PubMed1987

Influence of sexual differentiation on striatal and limbic catecholamines.

The influence of sexual differentiation of the brain on catecholamine content in the corpus striatum and limbic system was studied. Our results suggest that circulating ovary hormones during the critical period play an important role in the sexual differentiation of dopaminergic neurons in the corpus striatum and limbic system. Absence of androgenic steroids in the critical period leads to permanent alterations in the DA content of the limbic system in the male rat. Gonadectomy does not significantly alter NA levels in either of the two studied brain areas.

Animals↗
PubMed1987

Metabolism of histamine during pregnancy in the rat.

In order to clarify histamine metabolism during the period of pregnancy in which this amine attains the highest levels, pregnant and non-pregnant rats were submitted to four different treatments: 14C-histamine; 14C-histamine + histamine dihydrochloride; 14C-histamine + aminoguanidine; 14C-histidine. Paper chromatography and autoradiographic techniques were used to separate and to detect 14C-histamine metabolites. Total radioactivity excreted and percentages of histamine metabolites were calculated by liquid scintillation. Our results support two principal hypotheses: 1) Oxidation is the main catabolic pathway for histamine degradation in pregnant and non-pregnant rats. 2) Pregnant rats, in opposition to non-pregnant, show an increased capacity to metabolize histamine by oxidative deamination.

Amine Oxidase (Copper-Containing)↗
PubMed1986

A computational frame to study social behaviour in animals.

This paper presents new methods and procedures for studying collective behaviour in rats. The animals are assumed to be indistinguishable one from another and the behaviour of the group is represented analysed and interpreted in terms of the temporal evolution of a finite state probabilistic automaton. The automaton states are defined by measures on the clustering degree considered as a social response variable. The electronic system developed to carry out the cluster analysis and the automatic control of the social behaviour in the experimental environment includes a multimicroprocessor interacting with a 'social box' in which, together with classical sensors and effectors, a phototransistor based position sensor is included. Preliminary experiments show the discriminative power of the cluster automaton concerning sexual differences and emotivity, as well as the extensive of a basic mechanism of clustering as a collective response to stress. Pharmacologically, the new experimental medium proposed in this paper may be used to detect a new range of products affecting social but not individual behaviour. Also, well-known products, which in normal doses produce no detectable modification of individual behaviour, might have detectable effects on the collective level. Be this as it may, the experimental environment described constitutes a further experimental facility for the analysis and control of animal behaviour.

Animals↗
PubMed1986

Stress adaptation and adrenal activity in isolated and crowded rats.

Socially reared male control rats (Co) were compared with crowded reared rats (Cr) and isolated reared rats (I). We assayed the adaptation to moderate stress (activity and defecation rate in open-field test) and to intensive stress sensitivity to restraint ulcer), so as the basal adrenal activity measuring basal values of corticosterone (R.I.A.) and fresh weight of adrenal and thymus glands. Results show a great lack of adaptation to moderate and intensive stress in Cr and I reared rats which leads to a decrease of activity variables, an increase of defecation rates and a high sensitivity to restraint ulcers. The effect of crowding conditions show higher values than isolation. We also found, in isolated and crowded reared rats, an increase in the adrenal function with great values for the basal secretion of corticosterone and atrophy of the thymus gland, besides which, crowded reared animals showed adrenal hypertrophy.

Adrenal Glands↗