RESUMEN
The red fox (Vulpes vulpes) demonstrates a variety of coat colors including platinum, a common phenotype maintained in farm-bred fox populations. Foxes heterozygous for the platinum allele have a light silver coat and extensive white spotting, whereas homozygosity is embryonic lethal. Two KIT transcripts were identified in skin cDNA from platinum foxes. The long transcript was identical to the KIT transcript of silver foxes, whereas the short transcript, which lacks exon 17, was specific to platinum. The KIT gene has several copies in the fox genome: an autosomal copy on chromosome 2 and additional copies on the B chromosomes. To identify the platinum-specific KIT sequence, the genomes of one platinum and one silver fox were sequenced. A single nucleotide polymorphism (SNP) was identified at the first nucleotide of KIT intron 17 in the platinum fox. In platinum foxes, the A allele of the SNP disrupts the donor splice site and causes exon 17, which is part of a segment that encodes a conserved tyrosine kinase domain, to be skipped. Complete cosegregation of the A allele with the platinum phenotype was confirmed by linkage mapping (LOD 25.59). All genotyped farm-bred platinum foxes from Russia and the US were heterozygous for the SNP (A/G), whereas foxes with different coat colors were homozygous for the G allele. Identification of the platinum mutation suggests that other fox white-spotting phenotypes, which are allelic to platinum, would also be caused by mutations in the KIT gene.
Asunto(s)
Zorros/genética , Color del Cabello/genética , Proteínas Proto-Oncogénicas c-kit/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Mapeo Cromosómico , Exones , Datos de Secuencia Molecular , Mutación , Fenotipo , Polimorfismo de Nucleótido Simple , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
B chromosomes are often considered to be one of the most mysterious elements of karyotypes (Camacho, 2004). It is generally believed that mammalian B chromosomes do not contain any protein coding genes. The discovery of a conserved KIT gene in Canidae B chromosomes has changed this view. Here we performed analysis of sequences surrounding KIT in B chromosomes of the fox and raccoon dog. The presence of the RPL23A pseudogene was shown in canid B chromosomes. The 3' end fragment of the KDR gene was found in raccoon dog B chromosomes. The size of the B-specific fragment homologous to the autosome fragment was estimated to be a minimum of 480 kbp in both species. The origin and evolution of B chromosomes in Canidae are discussed.
Asunto(s)
Mapeo Cromosómico/métodos , Cromosomas/ultraestructura , Proteínas Proto-Oncogénicas c-kit/genética , Animales , Bandeo Cromosómico , Perros , Zorros , Biblioteca de Genes , Hibridación Fluorescente in Situ , Cariotipificación , Modelos Genéticos , Perros MapacheRESUMEN
The silver fox, a variant of the red fox (Vulpes vulpes), is a close relative of the dog (Canis familiaris). Cytogenetic differences and similarities between these species are well understood, but their genomic organizations have not been compared at higher resolution. Differences in their behavior also remain unexplained. Two silver fox strains demonstrating markedly different behavior have been generated at the Institute of Cytology and Genetics of the Russian Academy of Sciences. Foxes selected for tameness are friendly, like domestic dogs, while foxes selected for aggression resist human contact. To refine our understanding of the comparative genomic organization of dogs and foxes, and enable a study of the genetic basis of behavior in these fox strains, we need a meiotic linkage map of the fox. Towards this goal we generated a primary set of fox microsatellite markers. Four hundred canine microsatellites, evenly distributed throughout the canine genome, have been identified that amplify robustly from fox DNA. Polymorphism information content (PIC) values were calculated for a representative subset of these markers and population inbreeding coefficients were determined for tame and aggressive foxes. To begin to identify fox-specific single nucleotide polymorphisms (SNPs) in genes involved in the neurobiology of behavior, fox and dog orthologs of serotonin 5-HT1A and 5-HT1B receptor genes have been cloned. Sequence comparison of these genes from tame and aggressive foxes reveal several SNPs. The close relationship of the fox and dog enables canine genomic tools to be utilized in developing a fox meiotic map and mapping behavioral traits in the fox.
Asunto(s)
Agresión/fisiología , Mapeo Cromosómico , Zorros/genética , Animales , Secuencia de Bases , Cromosomas de los Mamíferos/genética , Cartilla de ADN , Zorros/fisiología , Marcadores Genéticos , Genética de Población , Repeticiones de Microsatélite/genética , Datos de Secuencia Molecular , Polimorfismo Genético/genética , Polimorfismo de Nucleótido Simple/genética , Receptores de Serotonina 5-HT1/genética , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
In this review, genes and proteins involved in cytokinesis and cell proliferation of cell-wall bacteria and mycoplasms are considered. We hope that this comparative analysis of genes and proteins of phylogenetically distant bacteria, including the minimal cells of mycoplasmas, can be useful for understanding the basic principles of prokaryotic cell division. The ftsZ gene was found among representatives of all bacterial groups. The recent data indicate that FtsZ protein plays the central role in the process of bacterial cell division. FtsZ protein was revealed in all Eubacterial groups (including mycoplasmas), in Archaebacteria and chloroplasts, All FtsZ proteins are able to form protofilaments as a result of polymerization in vitro and demonstrate GTF-ase activity. On the base of these properties and some similarities in amino acid sequences with tubulins, it has been suggested that FtsZ protein is an evolutionary ancestor of Eukaryotic tubulins. On the earliest stage of bacterial cytokinesis FtsZ protein assembles into a submembranous Z-ring which encircles bacterial cell in the predivisional site. Some other bacterial proteins take part in stabilization and contraction of the Z-ring, which is considered as a cytoskeleton-like bacterial structure.
Asunto(s)
Bacterias/genética , Proteínas Bacterianas/genética , Proteínas de Ciclo Celular/genética , Proteínas del Citoesqueleto , Genes cdcRESUMEN
The ftsZ gene was found among representatives of all bacterial groups. FtsZ protein is an essential component of cell division ring. Contraction of this cytoskeleton-like ring is believed to be the universal way of bacterial division. Acholeplasma laidlawii possesses all features of the minimal mycoplasma cell and some traits of cell-wall bacteria and seems to be a promising object for study of basic principles of the bacterial division process. We cloned an A. laidlawii chromosomal fragment containing ftsZ gene and two flanking orf which also were identified. A. laidlawii FtsZ protein has been determined with polyclonal antibodies raised in rabbit. It was demonstrated that ftsZ gene of A. laidlawii could be expressed in E. coli cells. We also revealed that A. laidlawii FtsZ had a low similarity to proteins of Mycoplasma genitalium and M. pneumoniae. The comparison of FtsZ structures may be used for investigation of bacterial phylogenetic relations.
Asunto(s)
Acholeplasma laidlawii/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas del Citoesqueleto , Acholeplasma laidlawii/inmunología , Secuencia de Aminoácidos , Anticuerpos Antibacterianos/inmunología , Especificidad de Anticuerpos , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/inmunología , Secuencia de Bases , Clonación Molecular , Escherichia coli/genética , Evolución Molecular , Genes Bacterianos/genética , Variación Genética/genética , Punto Isoeléctrico , Datos de Secuencia Molecular , Peso Molecular , Sistemas de Lectura Abierta/genética , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/inmunología , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
Gene ftsZ responsible for division of bacterial cells was revealed in most prokaryote groups. A 520-bp fragment of the ftsZ gene was amplified on the template of A. laidlawii DNA using degenerate primers. This fragment was sequenced and served as a hybridization probe for cloning of the full-sized copy of the A. laidlawii ftsZ gene. The amplified fragment was cloned in a pGEX3X vector and expressed in E. coli cells. Polyclonal antibodies derived from the chimeric polypeptide containing a fragment of A. laidlawii FtsZ protein interacted only with the A. laidlawii protein with molecular mass of 40 kDa. Comparison of nucleotide sequences of the ftsZ-gene region of A. laidlawii and other bacterial species showed that they were highly homologous in A. laidlawii, E. coli, and Bac. subtilis, while low homology was revealed between the A. laidlawii sequence and those of the members of the genus Mycoplasma. Analysis of the ftsZ-gene nucleotide sequences is suggested as a means to study the evolutionary relatedness of prokaryotes.