RESUMEN
A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.
Asunto(s)
Caenorhabditis elegans/genética , Drosophila melanogaster/genética , Genoma , Proteoma , Saccharomyces cerevisiae/genética , Animales , Apoptosis/genética , Evolución Biológica , Caenorhabditis elegans/química , Caenorhabditis elegans/fisiología , Adhesión Celular/genética , Ciclo Celular/genética , Drosophila melanogaster/química , Drosophila melanogaster/fisiología , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Genes Duplicados , Enfermedades Genéticas Congénitas/genética , Genética Médica , Proteínas del Helminto/química , Proteínas del Helminto/genética , Humanos , Inmunidad/genética , Proteínas de Insectos/química , Proteínas de Insectos/genética , Familia de Multigenes , Neoplasias/genética , Estructura Terciaria de Proteína , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/fisiología , Transducción de Señal/genéticaRESUMEN
Neurospora crassa and related heterothallic ascomycetes produce eight homokaryotic self-sterile ascospores per ascus. In contrast, asci of N. tetrasperma contain four self-fertile ascospores each with nuclei of both mating types (matA and mata). The self-fertile ascospores of N. tetrasperma result from first-division segregation of mating type and nuclear spindle overlap at the second meiotic division and at a subsequent mitotic division. Recently, Merino et al. presented population-genetic evidence that crossing over is suppressed on the mating-type chromosome of N. tetrasperma, thereby preventing second-division segregation of mating type and the formation of self-sterile ascospores. The present study experimentally confirmed suppressed crossing over for a large segment of the mating-type chromosome by examining segregation of markers in crosses of wild strains. Surprisingly, our study also revealed a region on the far left arm where recombination is obligatory. In cytological studies, we demonstrated that suppressed recombination correlates with an extensive unpaired region at pachytene. Taken together, these results suggest an unpaired region adjacent to one or more paired regions, analogous to the nonpairing and pseudoautosomal regions of animal sex chromosomes. The observed pairing and obligate crossover likely reflect mechanisms to ensure chromosome disjunction.
Asunto(s)
Cromosomas Fúngicos , Neurospora/genética , Recombinación Genética , Secuencia de Bases , Cruzamientos Genéticos , Intercambio Genético , Cartilla de ADNRESUMEN
The Genome Sequence DataBase (GSDB) is a database of publicly available nucleotide sequences and their associated biological and bibliographic information. Several notable changes have occurred in the past year: GSDB stopped accepting data submissions from researchers; ownership of data submitted to GSDB was transferred to GenBank; sequence analysis capabilities were expanded to include Smith-Waterman and Frame Search; and Sequence Viewer became available to Mac users. The content of GSDB remains up-to-date because publicly available data is acquired from the International Nucleotide Sequence Database Collaboration databases (IC) on a nightly basis. This allows GSDB to continue providing researchers with the ability to analyze, query and retrieve nucleotide sequences in the database. GSDB and its related tools are freely accessible from the URL: http://www.ncgr.org
Asunto(s)
Bases de Datos Factuales , Genoma , Almacenamiento y Recuperación de la Información , Propiedad , Análisis de SecuenciaRESUMEN
During 1998 the primary focus of the Genome Sequence DataBase (GSDB; http://www.ncgr.org/gsdb ) located at the National Center for Genome Resources (NCGR) has been to improve data quality, improve data collections, and provide new methods and tools to access and analyze data. Data quality has been improved by extensive curation of certain data fields necessary for maintaining data collections and for using certain tools. Data quality has also been increased by improvements to the suite of programs that import data from the International Nucleotide Sequence Database Collaboration (IC). The Sequence Tag Alignment and Consensus Knowledgebase (STACK), a database of human expressed gene sequences developed by the South African National Bioinformatics Institute (SANBI), became available within the last year, allowing public access to this valuable resource of expressed sequences. Data access was improved by the addition of the Sequence Viewer, a platform-independent graphical viewer for GSDB sequence data. This tool has also been integrated with other searching and data retrieval tools. A BLAST homology search service was also made available, allowing researchers to search all of the data, including the unique data, that are available from GSDB. These improvements are designed to make GSDB more accessible to users, extend the rich searching capability already present in GSDB, and to facilitate the transition to an integrated system containing many different types of biological data.
Asunto(s)
Secuencia de Bases , Bases de Datos Factuales , Genoma , Almacenamiento y Recuperación de la Información , Animales , Biología Computacional , Secuencia de Consenso , Expresión Génica , Genoma Humano , Humanos , Alineación de SecuenciaRESUMEN
We examined the phylogenetic relationships among five heterothallic species of Neurospora using restriction fragment polymorphisms derived from cosmid probes and sequence data from the upstream regions of two genes, al-1 and frq. Distance, maximum likelihood, and parsimony trees derived from the data support the hypothesis that strains assigned to N. sitophila, N. discreta, and N. tetrasperma form respective monophyletic groups. Strains assigned to N. intermedia and N. crassa, however, did not form two respective monophyletic groups, consistent with a previous suggestion based on analysis of mitochondrial DNAs that N. crassa and N. intermedia may be incompletely resolved sister taxa. Trees derived from restriction fragments and the al-1 sequence position N. tetrasperma as the sister species of N. sitophila. None of the trees produced by our data supported a previous analysis of sequences in the region of the mating type idiomorph that grouped N. crassa and N. sitophila as sister taxa, as well as N. intermedia and N. tetrasperma as sister taxa. Moreover, sequences from al-1, frq, and the mating-type region produced different trees when analyzed separately. The lack of consensus obtained with different sequences could result from the sorting of ancestral polymorphism during speciation or gene flow across species boundaries, or both.
