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Biomedical subjects

R Chaves

Publications and source records attributed to R Chaves.

13 recordsLinked to original sources
PubMed2006

Cattle rob(1;29) originating from complex chromosome rearrangements as revealed by both banding and FISH-mapping techniques.

Sixteen carriers of rob(1;29) (one of which was homozygous) from six different breeds (four Italian and two Portuguese), two heterozygous carriers of rob(26;29), three river buffaloes and two sheep were cytogenetically investigated in this study by using banding and FISH-mapping techniques (the latter only in cattle and river buffalo). Single- and dual- colour FISH were used with bovine probes containing both INRA143 (mapping proximally to BTA29) and bovine satellite (SAT) DNA SAT I, SAT III and SAT IV (mapping at the centromeric regions of cattle chromosomes). The combined use of these probes, the comparison of rob(1;29) with the dicentric rob(26;29) and with both river buffalo and sheep chromosomes (biarmed pairs) allowed us to hypothezise that rob(1;29) originated from complex chromosomal rearrangements through at least three sequential events: (a) centric fusion with the formation of a dicentric chromosome; (b) formation of a monocentric chromosome with loss of SAT I from both BTA1 and BTA29, most of SAT IV from BTA29 and, probably, some repeats of SAT III from BTA1; (c) double pericentric inversion or, more probably, a chromosome transposition of a small chromosome segment containing INRA143 from proximal p-arms to proximal q-arm of the translocated chromosome.

Animals↗
PubMed2006

Physical organization of the 1.709 satellite IV DNA family in Bovini and Tragelaphini tribes of the Bovidae: sequence and chromosomal evolution.

Repetitive DNA in the mammalian genome is a valuable record and marker for evolution, providing information about the order and driving forces related to evolutionary events. The evolutionarily young 1.709 satellite IV DNA family is present near the centromeres of many chromosomes in the Bovidae. Here, we isolated 1.709 satellite DNA sequences from five Bovidae species belonging to Bovini: Bos taurus (BTA, cattle), Bos indicus (BIN, zebu), Bubalus bubalis (BBU, water buffalo) and Tragelaphini tribes: Taurotragus oryx (TOR, eland) and Tragelaphus euryceros (TEU, bongo). Its presence in both tribes shows the sequence predates the evolutionary separation of the two tribes (more than 10 million years ago), and primary sequence shows increasing divergence with evolutionary distance. Genome organization (Southern hybridization) and physical distribution (in situ hybridization) revealed differences in the molecular organization of these satellite DNA sequences. The data suggest that the sequences on the sex chromosomes and the autosomes evolve as relatively independent groups, with the repetitive sequences suggesting that Bovini autosomes and the Tragelaphini sex chromosomes represent the more primitive chromosome forms.

Animals↗
PubMed2004

Standardization of MspI and HaeIII restriction karyotypes in cattle.

Cattle chromosomes were digested with two restriction endonucleases, MspI and HaeIII. The banding pattern induced by each enzyme allowed the identification and pairing of all individual chromosomes and consequently the elaboration of the karyotype. This method is rapid and technically easy, and proved to be of great utility in cattle cytogenetic studies.

Animals↗
PubMed2004

Restriction enzyme digestion chromosome banding in Crassostrea and Ostrea species: comparative karyological analysis within Ostreidae.

Reliable banding techniques are a major necessity for genetic research in oysters. In this study, we carried out the cytogenetic characterization of four oyster species (family Ostreidae) using restriction endonuclease treatments. Chromosomes were treated with three different restriction enzymes, stained with Giemsa, and examined for banding patterns. The following species were studied: Crassostrea gigas (2n = 20; total number of bands with ApaI, 74; HaeIII, 61; PstI, 76), Crassostrea angulata (2n = 20; ApaI, 62; HaeIII, 61; PstI, 55) (subfamily Crassostreinae), Ostrea edulis (2n = 20; ApaI, 82; HaeIII, 59; PstI, 66), and Ostrea conchaphila (2n = 20; ApaI, 68; HaeIII, 62; PstI, 69) (subfamily Ostreinae). Treatment of samples with ApaI, HaeIII, and PstI produced specific banding patterns, which demonstrates the potential of these enzymes for chromosome banding in oysters. This is of special interest, since it has been recently shown in mammalian chromosomes that restriction enzyme banding is compatible with fluorescence in situ hybridization. This study therefore provides a fundamental step in genome mapping of oysters, since chromosome banding with restriction enzymes facilitates physical gene mapping in these important aquaculture species. The analysis of the banded karyotypes revealed a greater similarity within the genera of Crassostrea and Ostrea than between them.

Animals↗
PubMed2004

Chromosomal localization of the major satellite DNA family (FA-SAT) in the domestic cat.

A major satellite DNA sequence was isolated from the cat genome and its sequencing data revealed homology to the FA-SAT family. In situ hybridization of the cat satellite DNA and telomeric sequences to cat chromosomes, together with staining of constitutive heterochromatin, allowed the physical mapping of the FA-SAT sequences, and also an overall constitutive heterochromatin study in cat chromosomes.

Animals↗
PubMed2003

Complex satellite DNA reshuffling in the polymorphic t(1;29) Robertsonian translocation and evolutionarily derived chromosomes in cattle.

We have analysed and mapped physically the satellite I, III (subunits pvu and sau) and IV DNA sequences in cattle using in-situ hybridization. Four breeds were analysed including individuals with a chromosome number of 2n = 60 and individuals with the widespread t(1;29) in the homozygous (2n = 58) and heterozygous state (2n = 59). All three satellite DNA families were present at the centromeres of the many but not all of the autosomal acrocentric chromosomes, and essentially absent from the sex chromosomes. In the translocated t(1;29) chromosome, the satellite DNA families showed a different pattern from that simply derived by fusion of the acrocentric autosomes and loss of satellite sequences, with no variation between breeds. A model of centromeric evolution is presented involving two independent events. Knowledge of mechanisms of translocation formation within cattle is important for a functional understanding of centromere and satellites, investigation of chromosomal abnormalities, and for understanding chromosomal fusion during evolution of other bovids and genome evolution in general.

Animals↗
PubMed2002

In situ hybridization and chromosome banding in mammalian species.

Chromosome banding is often required in conjunction with fluorescent in situ hybridization of labelled probes for chromosome painting, satellite DNA and low-copy sequences to allow identification of chromosomes and simultaneous probe localization. Here, we present a method that reveals both patterns with only one observation step. The band pattern is produced by restriction-enzyme digestion of chromosomes, followed by fixation with paraformaldehyde in PBS, a short chromosome denaturation step in hybridization solution, and then standard in situ hybridization, washing and detection protocols. Using a range of different mammalian species, chromosome-banding patterns were immediately recognizable, although synchronisation procedures normally required for high- resolution G-banding were not needed. Unlike other methods available, only one round of observation is required using a conventional fluorescence microscope, the method works without modification in many species, and in situ hybridization is not used for chromosome identification (allowing multiple targets and minimizing background). The banding pattern is probably generated by a combination of DNA dissolution and heterochromatin reorganisation after enzyme digestion, followed by paraformaldehyde fixation of the new chromatin structure and incomplete denaturation. The method is of widespread utility in comparative genomics and genome organization programmes.

Animals↗
PubMed2000

Eyelid abnormalities in lamellar ichthyoses.

PURPOSE: To describe eyelid abnormalities in lamellar ichthyoses (LI). DESIGN: Retrospective observational case series. PARTICIPANTS: Eight patients with classic LI and two patients with congenital ichthyosiform erythroderma. METHODS: Results of eyelid and corneal examinations of 10 patients with LI were reviewed and analyzed with emphasis on the relationship between eyelid ectropion and corneal damage. RESULTS: All patients presented with cicatricial lagophthalmos. Of the eight patients with classic LI, five had ectropion of the four eyelids, one had only lower ectropion, and two had no degree of ectropion. Two patients with congenital ichthyosiform erythroderma had distinct eyelid abnormalities, including madarosis and eyelash retraction. Loss of vision caused by corneal damage was found in three patients with classic LI. Of these three patients, two did not have upper eyelid ectropion. CONCLUSIONS: Severe corneal damage can occur in LI even if there is no upper or lower eyelid ectropion.

Adolescent↗
PubMed2000

Centromeric heterochromatin in the cattle rob(1;29) translocation: alpha-satellite I sequences, in-situ MspI digestion patterns, chromomycin staining and C-bands.

The centromeric regions and alpha-satellite I sequence were studied on chromosomes 1, 29 and the rob(1;29) translocation in a Portuguese breed of cattle, Barrosa, carrying the translocation. Rob(1;29) centromeric regions showed heterochromatic bands with propidium iodide but, unlike the acrocentric autosomes, no strong centromeric bands were revealed with chromomycin A3. An alpha-satellite I sequence was not found at the centromeres of the X, Y and rob(1;29) chromosomes in the breed, although it was present at the centromeres of all acrocentric chromosomes including 1 and 29. Restriction enzyme banding with MspI revealed polymorphisms between different rob(1;29) chromosomes in both centromeric and intercalary regions. The data show that the centromeric region of the rob(1;29) chromosome has lost the alpha-satellite I sequences, while retaining other heterochromatin, and suggest that this important and widespread translocation has occurred multiple times.

Animals↗
PubMed2000

The species and chromosomal distribution of the centromeric alpha-satellite I sequence from sheep in the tribe Caprini and other Bovidae.

The evolution of chromosomes in species in the family Bovidae includes fusion and fission of chromosome arms (giving different numbers of acrocentric and metacentric chromosomes with a relatively conserved total number of arms) and evolution in both DNA sequence and copy number of the pericentromeric alpha-satellite I repetitive DNA sequence. Here, a probe representing the sheep alpha-satellite I sequence was isolated and hybridized to genomic DNA digests and metaphase chromosomes from various Bovidae species. The probe was highly homologous to the centromeric sequence in all species in the tribe Caprini, including sheep (Ovis aries), goat (Capra hircus) and the aoudad or Barbary sheep (Amnotragus lervia), but showed no detectable hybridization to the alpha-satellite I sequence present in the tribe Bovini and at most very weak to species in the tribes Hippotragini, Alcelaphini or Aepycerotini. The sex chromosomes of sheep, goat and aoudad did not contain detectable alpha-satellite I sequence; in sheep, one of the three metacentric autosomal chromosomes does not carry the sequence, while in aoudad, it is essentially absent in three large autosomal pairs as well as the large metacentric chromosome pair. The satellite probes can be used as robust chromosome and karyotype markers of evolution among tribes and increase the resolution of the evolutionary tree at the base of the Artiodactyla.

Animals↗
PubMed1999

The place of Callimico goeldii in the Callitrichine phylogenetic tree: evidence from von Willebrand factor gene intron II sequences.

Sequences of a 0.9-kb DNA segment spanning intron 11 of the von Willebrand Factor gene (vWF) were determined for 21 individuals of 19 primate species. The results of maximum parsimony and maximum likelihood analyses of these vWF sequences are congruent with previous molecular findings from other nonlinked nuclear genomic loci which divide the platyrrhine superfamily Ceboidea into three monophyletic families: Cebidae, Atelidae, and Pitheciidae. The vWF results strongly support the taxon Callitrichinae as a monophyletic subfamily within Cebidae. The four extant callitrichine genera constitute tribe Callitrichini, and the basal branchings within this tribe first separate out Saguinus (tamarins), next Leontopithecus (lion tamarins), and last the sister genera Callimico (Goeldi's monkeys) and Callithrix (marmosets). Callithrix divides into three subclades, with pygmy marmosets (C. pygmaea) as sister of the C. argentata species group and with the C. jacchus species group as their sister. Fossil and DNA evidence place the emergence of the callitrichine clade in the basal cebid radiation at about 20 Ma (million years ago) and the three basal branchings in the callitrichin radiation at about 13 to 11 Ma. In turn, the branchings separating the three subclades of Callithrix are placed at about 5 to 4 Ma.

Animals↗
PubMed1989

[Dental equilibration by selective grinding or occlusal adjustment].

Oclusal adjustment or selective grinding is an operative procedure that must be diagnosed and well planned before making in the patient the clinical steps. Thus it's critical to make the diagnosis and treatment planning by means of casts mounted on semiadjustables articulators, over which is necessary to work first. Remember that the oclusal adjustment is an irreversible media of dental structures substraction that can be made as a unique type of treatment before the operative dentistry and prostodontics. The elimination of the symptoms are the goal of the treatment, and a step that can't be avoided after an ortodontic treatment.

Dental Articulators↗