RESUMO
Plasmodium merozoites are covered by a complex coat of surface proteins. Several of the Merozoite Surface Proteins (MSPs) that make up this coat have been proposed as vaccine candidates although some of the MSPs are known to be highly polymorphic. We present here the first survey and analysis of the polymorphism in the recently characterized P. vivax surface protein PvMSP-3alpha. Full length or partial sequences were obtained for the Pvmsp-3alpha gene from isolates originating in Central and South America, Asia and the Pacific. The Pvmsp-3alpha sequence is remarkably diverse, but this extensive diversity is largely restricted to certain domains of the encoded protein. An acidic C-terminal domain and a smaller hydrophilic N-terminus are relatively conserved, while a central domain containing coiled-coil heptad repeats is highly polymorphic and in some isolates of P. vivax is partially deleted. Unlike other MSPs, there is no evidence of allelic families of PvMSP-3alpha gene sequences, and no evidence that certain patterns of polymorphism group within isolates of similar geographical origin. The distribution and nature of polymorphism suggest that there are functional restrictions on mutations in this gene, and have implications for inclusion of PvMSP-3alpha as a candidate in a P. vivax vaccine.
Assuntos
Plasmodium vivax/genética , Polimorfismo Genético , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Regulação da Expressão Gênica , Frequência do Gene , Proteínas de Membrana/química , Proteínas de Membrana/genética , Dados de Sequência Molecular , Peso Molecular , Família Multigênica , Filogenia , Estrutura Terciária de Proteína , Sequências Repetitivas de Aminoácidos , Alinhamento de SequênciaRESUMO
We report the isolation, characterization and analysis of the small subunit rRNA genes in Plasmodium cynomolgi (Ceylon). As in other Plasmodium species, these genes are present in low copy number, are unlinked and form two types that are distinct in sequence and are expressed stage specifically. The asexually expressed (type A) genes are present in four copies in the Ceylon- and in five copies in the Berok-strain. Surprisingly, the sexually expressed (type B) gene is present in a single copy. The vast majority of the differences between gene types is confined to the variable regions. The pattern of divergence is different from that observed in Plasmodium berghei or in Plasmodium falciparum. Analysis of the small subunit rRNA sequences of P. cynomolgi, P. berghei and P. falciparum, indicates that the two gene types do not evolve independently but rather interact (through gene conversion or some form of recombination) to such an extent as to erase whatever stage-specific sequence signatures they may have had in the last common ancestor.
Assuntos
Plasmodium cynomolgi/genética , RNA de Protozoário/genética , RNA Ribossômico/genética , Animais , Sequência de Bases , Evolução Biológica , Primers do DNA/genética , DNA Ribossômico/genética , Regulação da Expressão Gênica , Genes de Protozoários , Dados de Sequência Molecular , Plasmodium/genética , Plasmodium cynomolgi/crescimento & desenvolvimentoRESUMO
Plasmodium species exhibit the unprecedented situation of distinct, stage-specific rRNA sequences. We present an analysis of two pairs of sequences of the small rRNA subunit (Plasmodium falciparum and Plasmodium berghei) and show that these genes do not evolve independently and that in fact their evolution is dominated by gene conversion. This analysis also shows that no extensive stage-specific sequences are conserved in the two species, thus rendering unlikely that the existence of stage-specific rRNA genes results from a requirement for distinct rRNA types.
Assuntos
Evolução Biológica , Conversão Gênica , Plasmodium/genética , RNA Ribossômico/genética , Animais , Plasmodium berghei/genética , Plasmodium falciparum/genéticaAssuntos
DNA de Protozoário/análise , Fígado/parasitologia , Plasmodium yoelii/crescimento & desenvolvimento , Sondas RNA , RNA Ribossômico/genética , Animais , Sequência de Bases , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Plasmodium yoelii/genética , RNA de Protozoário/genéticaRESUMO
Southern blot analysis of various genes was used to compare the human promyelocytic leukemia cell line HL-60 and the BII cell line, which reportedly arose as a spontaneous differentiation inducer-resistant variant from an HL-60 culture. Granulocyte-macrophage colony stimulating factor gene restriction fragment polymorphism, due to a partial deletion of one of the alleles of this gene in HL-60, was not observed in the BII cells. Furthermore, the p53 oncogene, most of which is deleted in the HL-60 cell line, was found to be intact in the BII cell line. Human leukocyte antigen typing revealed that the two cell lines shared the A locus but differed at the B locus. Several unique restriction fragments hybridizing to human leukocyte antigen class I and DR beta gene probes were observed in the DNA digests of each cell line. Altogether these data provide definitive evidence that BII represents a human cell line of different origin than HL-60. Further lineage determination of this cell line could add a useful member to the group of leukemic cell lines.
