RESUMO
Urban historians have greatly expanded their geographical purview in recent years, incorporating suburbs and hinterlands into their analysis of social and environmental change. Urban environmental historians and suburban historians have played a critical role in the regionalization of urban history over the last decade. This case study of the development of New York City's water supply reveals the benefits of taking a regional approach to urban history. From the New York Public Library to Central Park's Great Lawn to neighborhood parks, the New York City landscape bears the traces of the continuous development of the city's water network. Expansion of the water system in rural hinterlands enabled municipal officials to put urban reservoirs to new uses, creating some of the city's most beloved public spaces. The rehabilitation of urban infrastructure underscores the intimate linkages between rural development and the urban built environment.
Assuntos
Planejamento de Cidades , Saúde Pública , Saneamento , População Urbana , Urbanização , Abastecimento de Água , Planejamento de Cidades/economia , Planejamento de Cidades/educação , Planejamento de Cidades/história , Planejamento de Cidades/legislação & jurisprudência , Água Potável , História do Século XIX , História do Século XX , História do Século XXI , Cidade de Nova Iorque/etnologia , Saúde Pública/economia , Saúde Pública/educação , Saúde Pública/história , Saúde Pública/legislação & jurisprudência , Saneamento/economia , Saneamento/história , Saneamento/legislação & jurisprudência , População Urbana/história , Urbanização/história , Urbanização/legislação & jurisprudência , Abastecimento de Água/economia , Abastecimento de Água/história , Abastecimento de Água/legislação & jurisprudênciaRESUMO
The Candida albicans ALS (agglutinin-like sequence) gene family encodes eight cell-surface glycoproteins, some of which function in adhesion to host surfaces. ALS genes have a central tandem repeat-encoding domain comprised entirely of head-to-tail copies of a conserved 108-bp sequence. The number of copies of the tandemly repeated sequence varies between C. albicans strains and often between alleles within the same strain. Because ALS alleles can encode different-sized proteins that may have different functional characteristics, defining the range of allelic variability is important. Genomic DNA from C. albicans strains representing the major genetic clades was PCR amplified to determine the number of tandemly repeated sequence copies within the ALS5 and ALS6 central domain. ALS5 alleles had 2-10 tandem repeat sequence copies (mean=4.82 copies) while ALS6 alleles had 2-8 copies (mean=4.00 copies). Despite this variability, tandem repeat copy number was stable in C. albicans strains passaged for 3000 generations. Prevalent alleles and allelic distributions varied among the clades for ALS5 and ALS6. Overall, ALS6 exhibited less variability than ALS5. ALS5 deletions can occur naturally in C. albicans via direct repeats flanking the ALS5 locus. Deletion of both ALS5 alleles was associated particularly with clades III and SA. ALS5 exhibited allelic polymorphisms in the coding region 5' of the tandem repeats; some alleles resembled ALS1, suggesting recombination between these contiguous loci. Natural deletion of ALS5 and the sequence variation within its coding region suggest relaxed selective pressure on this locus, and that Als5p function may be dispensable in C. albicans or redundant within the Als family.
Assuntos
Candida albicans/genética , Moléculas de Adesão Celular/genética , Proteínas Fúngicas/genética , Glicoproteínas de Membrana/genética , Alelos , Sequência de Bases , Southern Blotting , Candida albicans/crescimento & desenvolvimento , DNA Fúngico/química , DNA Fúngico/genética , Europa (Continente) , Deleção de Genes , Dosagem de Genes , Frequência do Gene , Variação Genética , Genoma Fúngico , Geografia , Dados de Sequência Molecular , América do Norte , Análise de Sequência de DNA , África do Sul , América do Sul , Especificidade da Espécie , Sequências de Repetição em TandemRESUMO
It was previously demonstrated by a cluster analysis that 26 unrelated U.S. isolates of Candida albicans separated into three distinct groups (groups I, II, and III) while South African isolates separated into four distinct groups (groups I, II, III, and SA). To verify the absence or underrepresentation of SA isolates in North America, and to identify which groups are represented in Europe and South America, collections of bloodstream isolates from each geographical locale were analyzed by cluster analyses based on genetic fingerprinting with the Ca3 probe. The results verify that North America is almost devoid of SA isolates (2%). However, the results reveal a new clade, designated group E, relatively specific to Europe. While 26% of a European collection of 46 isolates was composed of group E isolates, only 2% of the 164 North American isolates, 5% of 22 South American isolates, and 1% of 361 South African isolates were composed of group E isolates. The North American collection proved to be the least-diverse collection in regard to group representation. In a comparison of collections from the Northeast, Midwest, and Southwest regions of the United States, Canada, and South America, it was demonstrated that both the U.S. Southwest and the South American collections were devoid of group II isolates. Together these results identify for the first time a European-specific clade and demonstrate clear distinctions in the representations of the five demonstrated clades (groups I, II, III, SA, and E) in different geographical locales.