RESUMO
Zygophyllum species are succulent plants that are drought resistant and/or salt tolerant, growing under severe, dry climatic conditions. Despite their importance and abundance in the Mediterranean and Middle East regions, there is little information concerning molecular variations among species of this genus. Genetic diversity was assessed, using RAPD primers, of 12 populations of Z. coccineum, Z. album and Z. aegyptium collected from various locations in Egypt and Saudi Arabia. Yong leaves were used for DNA extraction. Genetic distances were calculated using Nei's method. A dendrogram was constructed based on the similarity data matrix by unweighted pair group method using arithmetic averages cluster analysis. Analysis with RAPD markers revealed genetic variation between and within populations of Zygophyllum. Zygophyllum coccineum showed higher levels of genetic variation and more unique alleles than the other species.
Assuntos
Variação Genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Zygophyllaceae/genética , Análise por Conglomerados , Filogenia , Polimorfismo Genético , Zygophyllaceae/classificaçãoRESUMO
We have characterized the circumsporozoite (CS) gene sequences of Plasmodium malariae China-1 CDC, isolated recently from a person who was infected 50 years ago in China, and P. vivax Chesson, isolated 48 years ago from a patient who had returned from New Guinea. These protein sequences were compared with the CS protein sequences of recently isolated P. vivax and P. malariae parasites. In a similar manner, we compared the previously characterized CS protein gene of P. falciparum clone 7G8, derived from a Brazilian isolate collected in 1980, with the CS protein genes of recent P. falciparum field isolates. In the case of the P. malariae CS protein gene, with the exception of an additional copy of major (NAAG) and minor (NDAG) repeat sequences and the presence of one copy of NDEG sequence, the China-1 CDC P. malariae parasite is similar to the Uganda-1 CDC isolate of 1982. In the nonrepeat region, changes were noted in two amino acid residues, one of which is also seen in a closely related monkey malaria parasite, P. brasilianum. In the case of P. vivax CS proteins, the nonrepeat region of the protein in Chesson strain shares identity with nearly 71% of the CS clones characterized from field isolates. In the P. falciparum CS proteins, the 7G8 CS protein sequence is identical to 75% of the genes of recent field isolates in the Th1R-N1 region. In the Th2R and Th3R regions, 34% and 55% of the CS clones analyzed, respectively, had changes at two amino acid residues.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Plasmodium malariae/genética , Plasmodium vivax/genética , Polimorfismo Genético , Proteínas de Protozoários/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Brasil , Clonagem Molecular , Primers do DNA/química , Gâmbia , Variação Genética , Humanos , Dados de Sequência Molecular , Papua Nova Guiné , Plasmodium malariae/química , Plasmodium vivax/química , Proteínas de Protozoários/química , Sequências Repetitivas de Ácido Nucleico , Estudos RetrospectivosRESUMO
Passage of malaria-infected blood through a two-layered column composed of acid-washed glass beads and CF 11 cellulose removes white cells from parasitized blood. However, because use of glass beads and CF 11 cellulose requires filtration of infected blood separately through these two resins and the addition of ADP, the procedure is time-consuming and may be inappropriate for use in the field, especially when large numbers of blood samples are to be treated. Our modification of this process yields parasitized cells free of contaminating leukocytes, and because of its operational simplicity, large numbers of blood samples can be processed. Our procedure also compares well with those using expensive commercial Sepacell resins in its ability to separate leukocytes from whole blood. As a test of usefulness in molecular biologic investigations, the parasites obtained from the blood of malaria-infected patients using the modified procedure yield genomic DNA whose single copy gene, the circumsporozoite gene, efficiently amplifies by polymerase chain reaction.
Assuntos
Separação Celular/métodos , Celulose , Cromatografia/métodos , Vidro , Leucócitos , Malária Falciparum/sangue , Malária Vivax/sangue , Microesferas , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Difosfato de Adenosina/farmacologia , Adsorção , Animais , Sequência de Bases , Separação Celular/instrumentação , DNA de Protozoário/genética , DNA de Protozoário/isolamento & purificação , Filtração , Genes de Protozoários , Humanos , Leucócitos/parasitologia , Malária Falciparum/parasitologia , Malária Vivax/parasitologia , Dados de Sequência Molecular , Plasmodium falciparum/genética , Plasmodium vivax/genética , Ativação Plaquetária , Proteínas de Protozoários/genéticaRESUMO
The circumsporozoite (CS) protein that covers the surface of infectious sporozoites is a candidate antigen in malaria vaccine development. To determine the extent of B- and T-epitope polymorphism and to understand the mechanisms of antigenic variability, we have characterized the CS protein gene of Plasmodium vivax from field isolates representing geographically distant regions of Papua New Guinea (PNG) and Brazil. In the central repeat region of the CS protein, in addition to variation in the number of repeats, an array of mutations was observed which suggests that point mutations have led to the emergence of the variant CS repeat sequence ANGA(G/D)(N/D)QPG from GDRA(D/A)GQPA. Outside the repeat region of the protein, the nonsilent nucleotide substitutions of independent origin are localized in three domains of the protein that either harbor known T-cell determinants or are analogous to the Plasmodium falciparum immunodominant determinants, Th2R and Th3R. We have found that, with the exception of one CS clone sequence that was shared by one P. vivax isolate each from PNG and Brazil, the P. vivax CS protein types can be grouped into Papuan and Brazilian types. These results suggest that an in-depth study of parasite population dynamics is required before field trials for vaccine formulation based on polymorphic immunodominant determinants are conducted.