RESUMO
Advances in molecular analyses have permitted documentation of an increasing spectrum of mycobacteria infecting fish. Although some of these mycobacteria are not closely related, several species belong to the Mycobacterium tuberculosis clade. One member of the clade, M. marinum, is well known as an agent of piscine mycobacteriosis. Three other clade species, M. shottsii, M. pseudoshottsii and M. 'chesapeaki', have recently been identified as predominant disease agents in a widespread, continuing epizootic in wild striped bass of the Chesapeake Bay. A fifth clade member, M. ulcerans, has recently been indirectly detected in wild, African cichlid fish. As M. ulcerans is the third most common human mycobacterial infection worldwide, even such indirect evidence of M. ulcerans in fish must be more thoroughly investigated. Complicating the differentiation of these clade members is the growing recognition of intraspecies and interspecies variation in phenotypes, genes and virulence. Thus, researchers must be aware of the variety of piscine isolates within the M. tuberculosis clade. This review summarizes the methods of detection and differentiation for this important group of mycobacteria.
Assuntos
Técnicas Bacteriológicas/métodos , Doenças dos Peixes/microbiologia , Genes Bacterianos/genética , Infecções por Mycobacterium não Tuberculosas/veterinária , Micobactérias não Tuberculosas/classificação , Animais , Toxinas Bacterianas , Doenças dos Peixes/classificação , Peixes , Macrolídeos , Infecções por Mycobacterium não Tuberculosas/classificação , Mycobacterium marinum/classificação , Mycobacterium marinum/genética , Mycobacterium tuberculosis/classificação , Mycobacterium tuberculosis/genética , Micobactérias não Tuberculosas/genética , Fenótipo , Reação em Cadeia da Polimerase/métodos , Especificidade da EspécieRESUMO
We isolated a Mycobacterium sp. resembling Mycobacterium marinum and M. ulcerans from diseased striped bass (Morone saxatilis) during an epizootic of mycobacteriosis in the Chesapeake Bay. This isolate may represent an undescribed Mycobacterium species, based on phenotypic characteristics and comparative 16S rRNA gene sequence.
Assuntos
Bass/microbiologia , Doenças dos Peixes/microbiologia , Infecções por Mycobacterium/veterinária , Mycobacterium/classificação , Mycobacterium/isolamento & purificação , Animais , Doenças dos Peixes/epidemiologia , Genes de RNAr , Dados de Sequência Molecular , Mycobacterium/genética , Infecções por Mycobacterium/epidemiologia , Infecções por Mycobacterium/microbiologia , Fenótipo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Úlcera Cutânea/microbiologia , Úlcera Cutânea/veterináriaRESUMO
Aging has been associated with intrinsic changes of the humoral immune response, which may lead to an increased occurrence of autoimmune disorders and pathogenic susceptibility. The transcription factor Pax-5 is a key regulator of B cell development. Pax-5a/B cell-specific activator protein and an alternatively spliced isoform, Pax-5d, may have opposing functions in transcriptional regulation due to the lack of a transactivation domain in Pax-5d. To study B cell-specific changes that occur during the aging process, we investigated expression patterns of Pax-5a and 5d in mature B cells of young and aged mice. RNase protection assays showed a similar transcriptional pattern for both age groups that indicates that aging has no affect on transcription initiation or alternative splicing for either isoform. In contrast, a significant reduction in the DNA binding activity of Pax-5a but not Pax-5d protein was observed in aged B cells in vitro, while Western blot analyses showed that similar levels of Pax-5a and 5d proteins were present in both age groups. The observed decrease in Pax-5a binding activity correlated with changes in expression of two Pax-5 target genes in aged B cells. Expression of the Ig J chain and the secreted form of Ig mu, which are both known to be suppressed by Pax-5a in mature B cells, were increased in B cells of aged mice. Together, our studies suggest that changes associated with the aging phenotype cause posttranslational modification(s) of Pax-5a but not Pax-5d, which may lead to an abnormal B cell phenotype in aged mice, associated with elevated levels of J chain, and secretion of IgM.
