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Biomedical subjects

I Marín

Publications and source records attributed to I Marín.

At least 19 recordsLinked to original sources
PubMed2006

Dental arch diameters and relationships to oral habits.

The objective was to analyze variations in dental arch width in relation to oral habits. Maxillary and mandibular intercanine and intermolar distance were determined in relation to certain oral habits in 1297 children (ages 3 to 6 years). After an oral examination, the parents of each child completed a questionnaire about oral habits, including the use of a dummy or a bottle (or both), finger sucking, mouth breathing, breast- or bottle-feeding, and duration of these habits. Data were subjected to statistical analysis by the chi-square test for qualitative variables and analysis of variance for quantitative variables with homogeneous variances. Statistical significance was P < .05. In general, the maxillary arch was larger than the mandibular arch with regard to both the intercanine and the intermolar distances and more significantly so in boys. In relation to age, a significant increase was found only for the mandibular intercanine distance (P = .001). When arch width was analyzed in relation to various oral habits, the maxillary intercanine distance was less in children who used a dummy, especially one of a round design (P = .003). The maxillary intercanine distance was also less in children who breathed through their mouth (P = .002). In most cases, dummy use and mouth breathing were associated with a reduction in the intercanine distance in the maxillary arch. A dummy habit leads to a reduction in maxillary arch width, and mouth breathing causes a reduction in the size of both arches.

Age Factors↗
PubMed2003

[Interventional radiology, angioplasty and TIPS in Budd-Chiari syndrome].

INTRODUCTION: Budd-Chiari syndrome consists of complete or partial obstruction of the hepatic veins. Many treatment options are available; new interventional radiology techniques may play an important role as an alternative to surgical shunting. PATIENTS AND METHOD: Of 11 patients diagnosed with Budd-Chiari syndrome, 7 were treated with percutaneous balloon angioplasty or transjugular intrahepatic portosystemic shunt (TIPS) (2 and 5 patients, respectively). The efficacy of both techniques in the treatment of this syndrome was evaluated. RESULTS: Two patients presented significant isolated stenosis of a suprahepatic vein and underwent percutaneous balloon angioplasty. In both patients outcome was favorable with resolution of ascites. Five patients underwent TIPS and four showed clinical improvement with significant reduction in Child-Pugh score (p < 0.05) and resolution of ascites. No shunt malfunction was detected during follow-up. One patient showed no improvement after placement of TIPS and died soon after the procedure and a further two died from their underlying disease during follow-up. CONCLUSIONS: Treatment of Budd-Chiari syndrome requires multidisciplinary evaluation and should be individualized. In patients with Budd-Chiari syndrome uncontrolled by medical therapy, TIPS may become the decompressive method of choice as an alternative to surgical shunting. Liver transplantation may be reserved to patients in whom these techniques are ineffective.

Adult↗
PubMed2001

Detecting changes in the functional constraints of paralogous genes.

We describe a new procedure to determine whether regional alterations in the evolutionary constraints imposed on paralogous proteins have occurred. We used as models the A and B (alternatively called alpha and beta) subunits of V/F/A-ATPases, originated by a gene duplication more than 3 billion years ago. Changes associated to three major splits (eubacteria versus Archaea-eukaryotes; Archaea versus eukaryotes; and among free-living bacteria and symbiotic mitochondria) were studied. Only in the first case, when we compared eubacterial or mitochondrial F-ATPases versus eukaryotic vacuolar V-ATPases or archaeal A-ATPases, constraint changes were observed. Modifications in the degree of regional constraining were not detected for the other two types of comparisons (V-ATPases versus A-ATPases and within F-ATPases, respectively). When the rates of evolution of the two subunits were compared, it was found that F-ATPases regulatory subunits evolved faster than catalytic subunits, but the opposite was true for A- and V-ATPases. Our results suggest that, even for universal and essential proteins, selective constraints may be occasionally altered. On the other hand, in some cases no changes were detected after periods of more than 2.2 billion years.

Adenosine Triphosphatases↗
PubMed2001

Tracing the origin of the compensasome: evolutionary history of DEAH helicase and MYST acetyltransferase gene families.

Dosage compensation in Drosophila is mediated by a complex of proteins and RNAs called the "compensasome." Two of the genes that encode proteins of the complex, maleless (mle) and males-absent-on-the-first (mof), respectively, belong to the DEAH helicase and MYST acetyltransferase gene families. We performed comprehensive phylogenetic and structural analyses to determine the evolutionary histories of these two gene families and thus to better understand the origin of the compensasome. All of the members of the DEAH and MYST families of the completely sequenced Saccharomyces cerevisiae and Caenorhabditis elegans genomes, as well as those so far (June 2000) found in Drosophila melanogaster (for which the euchromatic part of the genome has also been fully sequenced) and Homo sapiens, were analyzed. We describe a total of 39 DEAH helicases in these four species. Almost all of them can be grouped in just three main branches. The first branch includes the yeast PRP2, PRP16, PRP22, and PRP43 splicing factors and their orthologs in animal species. Each PRP gene has a single ortholog in metazoans. The second branch includes just four genes, found in yeast (Ecm16) and Drosophila (kurz) and their orthologs in humans and Caenorhabditis. The third branch includes (1) a single yeast gene (YLR419w); (2) six Drosophila genes, including maleless and spindle-E/homeless; (3) four human genes, among them the ortholog of maleless, which encodes RNA helicase A; and (4) three C. elegans genes, including orthologs of maleless and spindle-E. Thus, this branch has largely expanded in metazoans. We also show that, for the whole DEAH family, only MLE and its metazoan orthologs have acquired new protein domains since the fungi/animals split. We found a total of 17 MYST family proteins in the four analyzed species. We determined putative orthologs of mof in both C. elegans and H. sapiens, and we show that the most likely ortholog in yeast is the Sas2 gene. Moreover, a paralog of mof exists in Drosophila. All of these results, together with those found for a third member of the compensasome, msl-3, suggest that this complex emerged after the fungi/animals split and that it may be present in mammalian species. Both gene duplication and the acquisition of new protein modules may have played important roles in the origin of the compensasome.

Acetyltransferases↗
PubMed2001

Preparation of DNA suitable for PCR amplification from fresh or fixed single dinoflagellate cells.

A method is described to prepare total DNA from single cells of dinoflagellates, which can be used for PCR amplification. As model organisms, we used a stock strain of Alexandrium catenella and cells of Dinophysis acuminata harvested from the Atlantic Ocean. Fresh grown cells or cells maintained in different preservatives were tested as sources for DNA preparation. The method used to prepare DNA combines physicochemical and enzymatic procedures on cells embedded in agarose plugs or beads. The agarose pieces containing the DNA were used to perform PCR amplification of a fragment of DNA containing a 5.8S rRNA gene and the flanking internal transcribed spacers (ITS1 and ITS2).

Animals↗
PubMed2000

The evolution of dosage-compensation mechanisms.

Dosage compensation is the process by which the expression levels of sex-linked genes are altered in one sex to offset a difference in sex-chromosome number between females and males of a heterogametic species. Degeneration of a sex-limited chromosome to produce heterogamety is a common, perhaps unavoidable, feature of sex-chromosome evolution. Selective pressure to equalize sex-linked gene expression in the two sexes accompanies degeneration, thereby driving the evolution of dosage-compensation mechanisms. Studies of model species indicate that what appear to be very different mechanisms have evolved in different lineages: the male X chromosome is hypertranscribed in drosophilid flies, both hermaphrodite X chromosomes are downregulated in the nematode Caenorhabditis elegans, and one X is inactivated in mammalian females. Moreover, comparative genomic studies demonstrate that the trans-acting factors (proteins and non-coding RNAs) that have been shown to mediate dosage compensation are unrelated among the three lineages. Some tantalizing similarities in the fly and mammalian mechanisms, however, remain to be explained.

Animals↗
PubMed2000

Ty3/Gypsy retrotransposons: description of new Arabidopsis thaliana elements and evolutionary perspectives derived from comparative genomic data.

We performed a comprehensive analysis of the evolution of the Ty3/GYPSY: group of long-terminal-repeat retrotransposons (also known as METAVIRIDAE:). Exhaustive database searches allowed us to detect novel elements of this group. In particular, the Arabidopsis thaliana and Drosophila melanogaster genome sequencing projects have recently disclosed a large number of new Ty3/GYPSY: sequences. So far, elements of three different Ty3/GYPSY: lineages had been described for A. thaliana. Here, we describe six new lineages, which we have called Tit-for-tat1, Tit-for-tat2, Gimli, Gloin, Legolas, and Little Athila. We confirm that plant Ty3/GYPSY: elements form two main monophyletic groups. Moreover, our results suggest that at least four independent ancestral lineages existed before the monocot-dicot split, about 200 MYA. Twelve sequences from D. melanogaster that may correspond to new elements are also described. Some of these sequences are similar to those of OSVALDO: and Ulysses, two elements of the OSVALDO: clade that had never before been described for D. melanogaster. Comparative analyses of multiple organisms, some of them with completely sequenced genomes, show that the number of lineages of Ty3/GYPSY: elements is very variable. Thus, while only 1 lineage is present in Saccharomyces cerevisiae, at least 6 exist in Caenorhabditis elegans, at least 9 are present in the A. thaliana, and perhaps 20 are present in D. melanogaster. Finally, we suggest that the presence of a chromodomain-containing integrase, a feature of some closely related Ty3/GYPSY: elements of fungi, plants, and animals, may be used to define a new METAVIRIDAE: genus.

Amino Acid Sequence↗
PubMed2000

Origin and evolution of the regulatory gene male-specific lethal-3.

Dosage compensation in Drosophila is mediated by genes known as "male-specific lethals" (msls). Several msls, including male-specific lethal-3 (msl-3), encode proteins of unknown function. We cloned the Drosophila virilis msl-3 gene. Using the information provided by the sequences of the Drosophila melanogaster and D. virilis genes, we found that sequences of other species can be aligned along their entire lengths with msl-3. Among them, there are genes in yeasts (the Schizosaccharomyces pombe Alp13 gene, as well as a putative Alp13 homolog, found in Saccharomyces cerevisae) and in mammals (MRG15 and MSL3L1 and their relatives) plus uncharacterized sequences of the nematode Caenorhabditis elegans and the plants Arabidopsis thaliana, Lycopersicon esculentum, and Zea mays. A second Drosophila gene of this family has also been found. It is thus likely that msl-3-like genes are present in all eukaryotes. Phylogenetic analyses suggest that msl-3 is orthologous to the mammalian MSL3L1 genes, while the second Drosophila melanogaster gene (which we have called Dm MRG15) is orthologous to mammalian MRG15. These analyses also suggest that the msl-3/MRG15 duplication occurred after the fungus/animal split, while an independent duplication occurred in plants. The proteins encoded by these genes have similar structures, including a putative chromodomain close to their N-terminal end and a putative leucine zipper at their C-terminus. The possible functional roles of these proteins are discussed.

Amino Acid Sequence↗
PubMed1999

Characterization of nonenterotoxigenic Escherichia coli strains producing F17 fimbriae isolated from diarrheic lambs and goat kids.

Forty-five ovine and caprine nonenterotoxigenic Escherichia coli strains producing F17-related fimbriae were characterized with respect to the fimbrial structural subunit and adhesin subtypes produced. In addition, several characteristics related to the virulence of strains producing F17 fimbriae were studied. Most of the strains (73%) possessed the f17cA structural subunit gene, whereas the f17aA and f17dA genes were detected only on three (6%) and two (4%) strains, respectively. The f17bA gene was not detected. All but one of these strains possessed the f17G genes of the adhesin subfamily II. The only strain having the f17G gene of subfamily I possessed the structural subunit gene f17dA. Sequencing of the f17A and f17G genes of four selected strains confirmed the association of f17cA and f17dA structural subunit genes with the f17G genes of the adhesin subfamily II. These results indicated that adhesins of the subfamily II are prominent among ovine and caprine isolates and that they are indistinctly associated with the F17 structural subunit subtypes on these field strains. CS31A- and CNF2-related genes were not detected. Most of the strains adhered in vitro to ovine intestinal brush borders (36 of 45) and agglutinated the erythrocytes of different species in the presence of D-mannose (39 of 45). F17-positive strains produced colicin V (57%) and were resistant to the bactericidal effect of serum (91%) in significantly higher percentages than F17-negative strains (34% produced colicin V, and 66% were serum resistant). Thus, most of the studied ovine and caprine strains showed phenotypic characteristics of septicemic strains.

Amino Acid Sequence↗
PubMed1998

The evolutionary dynamics of sex determination.

REVIEW There is substantial cytogenetic data indicating that the process of sex determination can evolve relatively rapidly. However, recent molecular studies on the evolution of the regulatory genes that control sex determination in the insect Drosophila melanogaster, the nematode Caenorhabditis elegans, and mammals suggest that, although certain sex determination regulatory genes have evolved relatively rapidly, other sex determination regulatory genes are quite conserved. Thus, studies of the evolution of sex determination, a process that appears to have elements that undergo substantial evolutionary change and others that may be conserved, could provide substantial insights into the kinds of forces that both drive and constrain the evolution of developmental hierarchies.

Animals↗
PubMed1998

Genomic organization analysis of acidophilic chemolithotrophic bacteria using pulsed field gel electrophoretic techniques.

The genomic organization of acidophilic chemolithotrophic bacteria belonging to the genus Thiobacillus, Thiomonas and Leptospirillum was studied using pulsed field gel electrophoresis techniques (PFGE). The electrophoretic analysis of intact DNA prepared from different strains showed that all have a circular chromosome, with sizes ranging from 1.9 Mb for Leptospirillum ferrooxidans ATCC 49879, the smallest genome for an acidophilic strict chemolithoautotrophic microorganism, to 3.8 Mb for Thiomonas cuprina DSM 5495, the largest in this study. The number of extrachromosomal elements present varied from none, as observed in several isolates of Leptospirillum ferrooxidan, to five in Thiobacillus thiooxidans ATCC 8085. The mixotroph Thiomonas cuprina DSM 5495 was found to have a linear 50 kb megaplasmid which was inducible when the bacteria was grown in chemolithotrophic conditions. Low-frequency restriction fragment analysis (LFRFA) of different acidophilic chemolithotrophs and related species was carried out by PFGE to determine macrorestriction patterns for rare cutters (SpeI, XbaI, SwaI, PmeI), which were then used for taxonomic identification (karyotyping), genome size determination, and generation of physical and genetic maps.

Chromosome Mapping↗
PubMed1998

Evolutionary relationships among the members of an ancient class of non-LTR retrotransposons found in the nematode Caenorhabditis elegans.

We took advantage of the massive amount of sequence information generated by the Caenorhabditis elegans genome project to perform a comprehensive analysis of a group of over 100 related sequences that has allowed us to describe two new C. elegans non-LTR retrotransposons. We named them Sam and Frodo. We also determined that several highly divergent subfamilies of both elements exist in C. elegans. It is likely that several master copies have been active at the same time in C. elegans, although only a few copies of both Sam and Frodo have characteristics that are compatible with them being active today. We discuss whether it is more appropriate under these circumstances to define only 2 elements corresponding to the most divergent groups of sequences or up to 16, considering each subfamily a different element. The C. elegans elements are related to other previously described non-LTR retrotransposons (CR1, found in different vertebrates; SR1, from the trematode Schistosoma; Q and T1, from the mosquito Anopheles). All of these elements, according to the analysis of their reverse transcriptases, form a monophyletic cluster that we call the "T1/CR1 subgroup." Elements of this subgroup are thus ancient components of the genome of animal species. However, we discuss the possibility that these elements may occasionally be horizontally transmitted.

Amino Acid Sequence↗
PubMed1998

Anaerobic growth, a property horizontally transferred by an Hfr-like mechanism among extreme thermophiles.

Despite the fact that the extreme thermophilic bacteria belonging to the genus Thermus are classified as strict aerobes, we have shown that Thermus thermophilus HB8 (ATCC 27634) can grow anaerobically when nitrate is present in the growth medium. This strain-specific property is encoded by a respiratory nitrate reductase gene cluster (nar) whose expression is induced by anoxia and nitrate (S. Ramírez-Arcos, L. A. Fernández-Herrero, and J. Berenguer, Biochim. Biophys. Acta, 1396:215-1997). We show here that this nar operon can be transferred by conjugation to an aerobic Thermus strain, enabling it to grow under anaerobic conditions. We show that this transfer takes place through a DNase-insensitive mechanism which, as for the Hfr (high frequency of recombination) derivatives of Escherichia coli, can also mobilize other chromosomal markers in a time-dependent way. Three lines of evidence are presented to support a genetic linkage between nar and a conjugative plasmid integrated into the chromosome. First, the nar operon is absent from a plasmid-free derivative and from a closely related strain. Second, we have identified an origin for autonomous replication (oriV) overlapping the last gene of the nar cluster. Finally, the mating time required for the transfer of the nar operon is in good agreement with the time expected if the transfer origin (oriT) were located nearby and downstream of nar.

Amino Acid Sequence↗
PubMed1997

Sexual isolation in Drosophila. III. Estimating isolation using male-choice experiments.

It has been generally assumed that "choice experiments" are useful to measure sexual isolation between Drosophila strains or species. Theoretical models have demonstrated however that the results obtained using one of these designs, namely multiple-choice experiments, are insufficient to determine the degree of isolation, even under very favorable assumptions. In this work, a simple behavioral model is developed to test whether male-choice experiments can be used to measure sexual isolation in Drosophila. This model shows that, although the outcome of male-choice experiments is affected by differences in female receptivities, a procedure to estimate the minimum degree of isolation using this experimental design can be established. The application of the methods derived from the theoretical model to previously reported experimental data demonstrates that a substantial degree of isolation frequently exists intraspecifically, while isolation is far from complete interspecifically. These results have important implications for discussions based on the comparative analysis of Drosophila behavior, both intra- and interspecifically. Most especially, they are in contradiction with the expectations of the Recognition concept of species.

Animals↗
PubMed1997

Genomic organization of the metal-mobilizing bacterium Thiobacillus cuprinus.

The genomic organization of Thiobacillus cuprinus, a facultative chemolithotrophic bacterium that preferentially solubilizes copper from complex ores, has been studied by Pulsed Field Gel Electrophoresis (PFGE). It has been determined that T. cuprinus has a circular chromosome of about 3.8 Mb in size as concluded by analysis of gamma-irradiated total DNA and restriction analysis. Macrorestriction patterns for several restriction enzymes have been generated. Restriction enzymes AseI, DraI, SpeI, SwaI and XbaI give a number of fragments that can be adequately resolved by PFGE and then be used for electrophoretic karyotyping and for the construction of physical maps of the chromosome. Such a map has been constructed for the endonucleases SpeI and SwaI. The localization of several heterologous and homologous genes on the physical map, including those for rRNA, has paved the way for the construction of a genetic map.

Chromosomes↗
PubMed1997

Genomic organization of the acidophilic chemolithoautotrophic bacterium Thiobacillus ferrooxidans ATCC 21834.

The genomic organization of the acidophilic chemolithoautotrophic bacterium Thiobacillus ferrooxidans ATCC 21834 has been studied by pulsed-field gel electrophoresis (PFGE). Analysis of its intact DNA, as well as the restriction patterns obtained with several endonucleases, allowed the characterization of one circular chromosome of 2.9 Mb and one plasmid of 8.6 kb. The first complete and highly resolved physical map (86 restriction sites) of the chromosome of an acidophilic obligate chemolithoautotrophic bacterium has been constructed by using endonucleases PmeI, SwaI, XbaI, and SpeI. The rRNA and str operons have been located on the chromosomal physical map.

Acidithiobacillus thiooxidans↗