- BSc in Biology, from Universidad de Oriente, Venezuela, graduated with honors in 1992, got his PhD in Genetics in 1999 from Texas Aedit
Type II melanoma-associated antigens (MAGE) are a subgroup of about a dozen proteins found in various locations in the genome and expressed in normal tissues, thus are not related to cancer as the type I MAGE genes. This gene family... more
Type II melanoma-associated antigens (MAGE) are a subgroup of about a dozen proteins found in various locations in the genome and expressed in normal tissues, thus are not related to cancer as the type I MAGE genes. This gene family exists as a single copy in non-mammals and monotremata, but found as two copies in metatherians and occur as a diverse group in all eutherians. Our studies suggest MAGED2 as the ancestor of this subfamily and the most likely evolutionary history of eutherian type II MAGE genes is hereby proposed based on synteny conservation, phylogenetic relations, genome location, homology conservation and the protein and gene structures. Type II genes can be divided into two: those with 13 exons (MAGED1, MAGED2, TRO and MAGED4) and those with only one exon (MAGEE1, MAGEE2, MAGEF1, NSMCE3, MAGEH1, MAGEL2 and NDN) with different evolutionary patterns. We reconstructed the phylogenetic relationships among 23 mammalian species using the combined sequences of MAGED1, MAGED2, MAGEL2 and NDN, because of their high divergence, and found high levels of support, being able to resolve the phylogenetic relationships among Euarchontoglires, Laurasiatheria, Afrotheria and Xenarthra, as an example that small, but phylogenetically informative sequences, can be very useful for resolving basal mammalian clades.
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Q-band comparisons were made among representative species of the four genera of the tribe Bovini (Bos, Bison, Bubalus, Syncerus) as well as to selected outgroup taxa representing the remaining two tribes of the subfamily Bovinae (nilgai,... more
Q-band comparisons were made among representative species of the four genera of the tribe Bovini (Bos, Bison, Bubalus, Syncerus) as well as to selected outgroup taxa representing the remaining two tribes of the subfamily Bovinae (nilgai, Boselaphini; eland, Tragelphini), the Bovidae subfamily Caprinae (domestic sheep) and the family Cervidae (sika deer and white-tailed deer). Extensive autosomal arm homologies were noted, but relatively few derivative character states were shared. Focus was then made on variation of the sex chromosomes and the chromosomal distribution of nucleolar organizer regions (NORs). Bovine BAC clones were used in molecular cytogenetic analyses to decipher rearrangements of the sex chromosomes, and a pocket gopher 28s ribosomal probe was used to map the chromosomal locations of nucleolar organizing regions (NORs). Some of the more noteworthy conclusions drawn from the comparative analysis were that: 1. The Bovidae ancestral X chromosome was probably acrocentri...
Research Interests: Genetics, Artiodactyla, Cytogenetics, Bison, Deer, and 18 moreSheep, Animals, Sex chromosomes, Comparative Analysis, Karyotyping, Y chromosome, Biological evolution, Cattle, Repetitive DNA, Chromosome, White Tailed Deer, Nucleolus Organizer Region, X chromosome, Bos Taurus, Genetic Markers, Sex Chromosome, DNA probes, and Chromosome Banding
Maize meiotic mutant desynaptic (dy) was tested as a candidate recombination modifier gene because its effect is manifested in prophase I. Recombination rates for desynaptic (dy) and its wild type were compared in two ways: (1)... more
Maize meiotic mutant desynaptic (dy) was tested as a candidate recombination modifier gene because its effect is manifested in prophase I. Recombination rates for desynaptic (dy) and its wild type were compared in two ways: (1) segregation analysis using six linked molecular markers on chromosome 1L and (2) cytogenetic analysis using fluorescence in situ hybridization (FISH)-aided meiotic configurations observed in metaphase I. Chromosome 1L map lengths among the six linked markers were 45-63 cM for five F2 dy/dy plants, significantly lower than the wild-type F2 map distance of 72 cM. Chromosomes 2 and 6 were marked with rDNA FISH probes, and their map lengths were estimated from FISH-adorned meiotic configurations using the expectation-maximization algorithm. Chiasma frequencies for dy/dy plants were significantly reduced for both arms of chromosome 2, for chromosome arm 6L, and for eight unidentified chromosomes. There was a notable exception for the nucleolus-organizing region-be...
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The cultivation of animal cell tissue has aided in the study of cytological phenomena such as the mapping of genes through molecular cytogenetics, somatic hybrids and radiation hybrid. However, little has been studied as to the behavior... more
The cultivation of animal cell tissue has aided in the study of cytological phenomena such as the mapping of genes through molecular cytogenetics, somatic hybrids and radiation hybrid. However, little has been studied as to the behavior of established cell lines. The objective of this study was to charac- terize abnormalities that could occur in stable fibroblast lines of bovines. Cells were reproduced and treated with BrdU for 24 hours and then treated with colcemide. They were collected with KCl and then fixed with methanol-acetic acid (3:1). The chromo- some preparations were colored with Hoechst 33258 and in some cases specific chromosomes were labeled (BTA5, BTA6, BTA8, BTA9, and BTA23) with BAC hybridization clone probes containing genomic segments through fluorescence (FISH) in situ hybridization with. The results indicated several cytogenetic abnormalities that became evident when the number of replica- tions increased. 5% polyploidy was found, principally tetra- ploidy, and...
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DETECCIÓN DEL VIRUS DE LA NECROSIS INFECCIOSA HIPODÉRMICA Y HEMATOPOYÉTICA (IHHNV) EN CAMARONES BLANCOS CULTIVADOS ASINTOMÁTICOS, Litopenaeus vannamei (BOONE), EN VENEZUELA. Detection of the Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) in Asymtomatic Cultured White Shrimp, Litop...more
The Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) is a pathogen that may cause high mortalities in Litopenaeus stylirostris and the Runt Deformity Syndrome (RDS) in L. vannamei. In order to detect the presence of IHHNV in... more
The Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) is a pathogen that may cause high mortalities in Litopenaeus stylirostris and the Runt Deformity Syndrome (RDS) in L. vannamei. In order to detect the presence of IHHNV in asymptomatic, cultivated shrimp, it were analyzed shrimp samples of cultivated L. vannamei from 5 farms located in the east and west costs of
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We evaluated native marine microalgae isolated from NortheasternVenezuela, as food for Litopenaeus vannamei larvae,compared to six microalgae commonly used in aquaculture. We evaluated themicroalgal ingestability calculating the biomass... more
We evaluated native marine microalgae isolated from NortheasternVenezuela, as food for Litopenaeus vannamei larvae,compared to six microalgae commonly used in aquaculture. We evaluated themicroalgal ingestability calculating the biomass consumed by larvae, later weevaluated three monoalgal diets on protozoea stages of L.vannamei over 72 hr based on the larval biomass,RNA/DNAindex and the proportion of stage retarded larvae. The presence of everymicroalgae
Research Interests: Aquaculture, Litopenaeus Vannamei, Fisheries Sciences, Digestive Tract, Environmental Conditions, and 2 moreLarge Scale and Es un protole sencillo para probar la aceptación de especies de microalgas por organismos cultivables que sean filtradores como los camarones en sus etapas larvarias o los moluscos
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In view of the great importance of Sardinella aurita as a fisheries resource in the Caribbean region, we studied the genetic differentiation among the populations from Mochima, Gulf of Cariaco and Morro de Puerto Santo, eastern Venezuela,... more
In view of the great importance of Sardinella aurita as a fisheries resource in the Caribbean region, we studied the genetic differentiation among the populations from Mochima, Gulf of Cariaco and Morro de Puerto Santo, eastern Venezuela, and compared the levels of variation and population subdivision with populations from the Mediterranean and Atlantic coast of Africa (previously reported). For this,
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Artificial selection can significantly improve animal performance in culture, but one of the major concerns in genetic programs is inbreeding, which can affect fitness-related traits, and may have a significant negative impact on... more
Artificial selection can significantly improve animal performance in culture, but one of the major concerns in genetic programs is inbreeding, which can affect fitness-related traits, and may have a significant negative impact on production. We present the analysis of production records for 11 generations (1990–2001) of a Venezuelan strain of Penaeus vannamei under mass selection and maintained in a closed
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To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian... more
To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.