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1.
Parasitol Res ; 95(2): 79-89, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15583937

RESUMO

The systematics within the genus Trichobilharzia is complicated. After the description of the type species Trichobilharzia ocellata, the name was routinely used for nearly all European findings of ocellate furcocercariae. T. ocellata was also described from North America and Japan. However, the identity of T. ocellata remains questionable. Comparison of data from the literature showed differences among various T. ocellata isolates and led us to the conclusion that the North American and the Japanese findings are not identical with European T. ocellata. In addition, the description of T. szidati corresponds with the recently reported European T. ocellata isolates. Sequence analysis of the ITS region confirmed that they are identical.


Assuntos
Lymnaea/parasitologia , Schistosomatidae/classificação , Schistosomatidae/isolamento & purificação , Animais , Sequência de Bases , Aves/parasitologia , DNA de Helmintos/genética , DNA Intergênico/genética , Europa (Continente) , Feminino , Japão , Masculino , América do Norte , Filogenia , Schistosomatidae/genética , Especificidade da Espécie
2.
J Helminthol ; 78(3): 281-4, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15469635

RESUMO

During routine parasitological surveillance and monitoring activities within a National Control Programme for control of human schistosomiasis in Uganda, it was noted that cattle grazing in a water meadow immediately adjacent to Tonya primary school, where the prevalence of intestinal schistosomiasis in children was in excess of 90%, were unusually emaciated. To test the hypothesis that there may have been an anthropozoonotic focus of Schistosoma mansoni within the local herd, a young female heifer, clearly emaciated and c. 8 months old, was slaughtered from which schistosome worms were later recovered by dissection. As female worms inspected by microscopy were not gravid, morphological identification proved inconclusive but analysis of cytochrome oxidase subunit I (COI) and small subunit (SSU) ribosomal DNA sequences from these worms identified them as Schistosoma bovis Sonsino, 1876. This is the first substantiated report of S. bovis from Lake Albert, western Uganda. Further epidemiological surveys are needed to clarify the extent of bovine schistosomiasis within this region, particularly so since this lakeside plain has been earmarked as a future game reserve.


Assuntos
Doenças dos Bovinos/parasitologia , Schistosoma/isolamento & purificação , Esquistossomose/veterinária , Zoonoses/epidemiologia , Animais , Bovinos , Vetores de Doenças , Feminino , Esquistossomose/parasitologia , Uganda/epidemiologia
3.
Parasitology ; 127(Pt 2): 131-7, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12954014

RESUMO

Two recognized strains of Schistosoma intercalatum, one from the Democratic Republic of Congo (DRC), formerly Zaire, and the other from Cameroon, have been investigated using DNA sequences from 3 mitochondrial genes, cytochrome oxidase subunit 1 (cox1), NADH dehydrogenase subunit 6 (nad6) and the small ribosomal RNA gene (rrnS). In addition, partial DNA sequences from the nuclear large subunit ribosomal RNA gene (lsrDNA) were included within the study. Although partial lsrDNA alone reveals little taxonomic information, phylogenetic analysis of the mitochondrial data demonstrates a clear dichotomy between the 2 purported strains and it is proposed that they should be treated as distinct taxa. The 'original' S. intercalatum now falls relatively basal in the S. haematobium group, while the proposed new species is more derived and sister taxon to S. bovis and S. curassoni.


Assuntos
DNA Mitocondrial/genética , Genes de Helmintos/genética , Filogenia , Schistosoma/classificação , Schistosoma/genética , Animais , Variação Genética/genética , Especificidade da Espécie
4.
Parasitology ; 126(Pt 3): 203-24, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12666879

RESUMO

Schistosomes are digenean flukes, parasitic of birds, mammals and crocodiles. The family Schistosomatidae contains species of considerable medical and veterinary importance, which cause the disease schistosomiasis. Previous studies, both morphological and molecular, which have provided a good deal of information on the phylogenetics of this group, have been limited in the number of species investigated or the type or extent of molecular data used. This paper presents the most comprehensive phylogeny to date, based on the sequences of 3 genes, complete ribosomal small subunit rRNA and large ribosomal subunit rRNA, and mitochondrial cytochrome oxidase 1, sequenced from 30 taxa including at least 1 representative from 10 of the 13 known genera of the Schistosomatidae and 17 of the 20 recognized Schistosoma species. The phylogeny is examined using morphological characters, intermediate and definitive host associations and biogeography. Theories as to the origins and spread of Schistosoma are also explored. The principal findings are that Ornithobilharzia and Austrobilharzia form a sister group to the Schistosoma; mammalian schistosomes appear paraphyletic and 2 Trichobilharzia species, T. ocellata and T. szidati, seem to be synonymous. The position of Orientobilharzia within the Schistosoma is confirmed, as is an Asian origin for the Schistosoma, followed by subsequent dispersal through India and Africa.


Assuntos
Evolução Molecular , Genes de Helmintos/genética , Filogenia , Schistosomatidae/classificação , Schistosomatidae/genética , Animais , DNA de Helmintos/química , DNA de Helmintos/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Geografia , Interações Hospedeiro-Parasita , RNA Ribossômico/genética , Alinhamento de Sequência , Especificidade da Espécie
6.
Parasitology ; 123 Suppl: S181-96, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11769282

RESUMO

Gene mapping and the generation of linkage groups are fundamental to an understanding of the organization and relationships of genes and marker sequences, providing a framework with which to investigate their association with traits of interest. The abundance of techniques available for generating polymorphic molecular markers, and recent advances in high throughput screening, have allowed the extension of map analysis to the tropical freshwater snail Biomphalaria glabrata, an important intermediate host for Schistosoma mansoni. Direct comparison of gene expression by differential display screening, without prior identification of candidate genes, can be combined with mapping to quantify the involvement of specific sequences in the schistosome resistance response, and other important host-parasite interactions. Here we discuss the application of current and emergent technologies to gene characterization and linkage analysis in snail-schistosome interactions. Preliminary results from the analysis of comparative gene expression in resistant and susceptible snails are also presented.


Assuntos
Biomphalaria/genética , Ligação Genética , Schistosoma mansoni/crescimento & desenvolvimento , Animais , Biomphalaria/metabolismo , Biomphalaria/parasitologia , Mapeamento Cromossômico/métodos , Etiquetas de Sequências Expressas , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/genética , Marcadores Genéticos/genética , Interações Hospedeiro-Parasita , Humanos , Masculino , Repetições de Microssatélites/genética , Reação em Cadeia da Polimerase , Característica Quantitativa Herdável , Técnica de Amplificação ao Acaso de DNA Polimórfico , Esquistossomose mansoni/genética
7.
Parasitology ; 120 ( Pt 4): 399-407, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10811281

RESUMO

Changes in gene expression in Biomphalaria glabrata following infection with Schistosoma mansoni have been investigated using a modified differential display approach. RNA was extracted from ovotestis, mantle tissue and anterior nephridium of control and exposed snails at 2 time-points (4 h and 24 h) post-exposure and analysed by RNA fingerprinting. A number of transcripts were identified; some novel and some homologous to mRNAs in GenEMBL that were previously unknown in B. glabrata. Down regulation of one 241 bp mRNA expressed sequence fragment - with an open reading frame showing 48% identity to a cytochrome p450 over 80 residues - has been confirmed using semi-quantitative RT-PCR. Preliminary classification of B. glabrata cyp450 sequence shows it to fall into CLAN 2 of the cytochrome p450 superfamily. Differential display has been successful in identifying changes in gene expression in Biomphalaria glabrata upon infection with Schistosoma mansoni and promises to be a useful technique for the investigation of the interaction between host and parasite.


Assuntos
Biomphalaria/genética , Biomphalaria/parasitologia , Regulação da Expressão Gênica , Esquistossomose mansoni/veterinária , Animais , Sistema Enzimático do Citocromo P-450/biossíntese , Sistema Enzimático do Citocromo P-450/genética , Regulação Enzimológica da Expressão Gênica , Interações Hospedeiro-Parasita , Filogenia , Reação em Cadeia da Polimerase/veterinária , RNA Mensageiro/química , Schistosoma mansoni/classificação , Esquistossomose mansoni/genética
8.
Proc Biol Sci ; 267(1460): 2351-8, 2000 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-11133023

RESUMO

Freshwater snails of the genus Biomphalaria, Preston 1910, are the most important and widely distributed intermediate hosts of Schistosoma mansoni, the blood fluke responsible for human intestinal schistosomiasis, in Africa and the Neotropics. S. mansoni is thought to have been imported repeatedly into the Americas during the last 500 years with the African slave trade. Surprisingly considering that the New and Old World separated 95-106 million years (Myr) ago, the disease rapidly became established due to the presence of endemic susceptible hosts. Reconstructing the phylogenetic relationships within Biomphalaria may provide insights into the successful intercontinental spread of S. mansoni. Parsimony and distance analyses of mitochondrial and nuclear sequences show African taxa to be monophyletic and Neotropical species paraphyletic, with Biomphalaria glabrata forming a separate clade from other Neotropical Biomphalaria, and ancestral to the African taxa. A west to east trans-Atlantic dispersal of a B. glabrata-like taxon, possibly as recently as the Plio-Pleistocene (1.8-3.6 Myr ago) according to a general mitochondrial clock, would fit these observations. Vicariance or an African origin for B. glabrata followed by multiple introductions to South America over the past 500 years with the African slave trade seem unlikely explanations. Knowledge of the phylogenetic relationships among important intermediate host species may prove useful in furthering control measures which exploit genetic differences in susceptibility to parasites, and in elucidating the evolution of schistosome resistance.


Assuntos
Biomphalaria/genética , Biomphalaria/parasitologia , Vetores de Doenças , Schistosoma mansoni/patogenicidade , África , Animais , DNA Mitocondrial/genética , Evolução Molecular , Genética Populacional , Humanos , Filogenia , Esquistossomose mansoni/transmissão , América do Sul , Especificidade da Espécie
10.
Mem Inst Oswaldo Cruz ; 93 Suppl 1: 111-6, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9921331

RESUMO

The relationship between schistosomes and their intermediate hosts is an extremely intricate one with strains and species of the parasite depending on particular species of snail, which in turn may vary in their susceptibility to the parasites. In order to gain a better understanding of the epidemiology of the disease we have been investigating the use of molecular markers for snail identification and for studying host-parasite relationships. In this paper we will draw on examples concerning schistosomiasis in West and East Africa to illustrate how a molecular analysis can be used as part of a "total evidence" approach to characterisation of Bulinus species and provide insights into parasite transmission. Particular emphasis is given to ribosomal RNA genes (rRNA), random amplified polymorphic DNA (RAPDs) and the mitochondrial gene cytochrome oxidase I (COI). Snails resistant to infection occur naturally and there is a genetic basis for this resistance. In Biomphalaria glabrata resistance to Schistosoma mansoni is known to be a polygenic trait and we have initiated a preliminary search for snail genomic regions linked to, or involved in, resistance by using a RAPD based approach in conjunction with progeny pooling methods. We are currently characterising a variety of STSs, (sequence tagged sites) associated with resistance. These can be used for local linkage and interval mapping to define genomic regions associated with the resistance trait. The development of such markers into simple dot-blot or specific PCR-based assays may have a direct and practical application for the identification of resistant snails in natural populations.


Assuntos
Biomphalaria/genética , Bulinus/genética , RNA Ribossômico/genética , Animais , Complexo IV da Cadeia de Transporte de Elétrons/genética , Interações Hospedeiro-Parasita/genética
11.
Gene ; 191(2): 143-8, 1997 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-9218712

RESUMO

A cDNA which encodes a calnexin (Cnx)-like protein from Drosophila melanogaster has been characterized. The deduced amino acid sequence shares several regions of homology with Cnx from other sources with two conserved motifs each repeated four times. The gene was found to be transcribed in various tissues and at all developmental stages. We have mapped the gene at chromosomal position 99A and we have also mapped the related gene coding for Drosophila calreticulin at 85E.


Assuntos
Proteínas de Ligação ao Cálcio/genética , Drosophila melanogaster/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Proteínas de Ligação ao Cálcio/química , Calnexina , Calreticulina , Mapeamento Cromossômico , Clonagem Molecular , Sequência Conservada , DNA Complementar , Regulação da Expressão Gênica no Desenvolvimento , Hibridização In Situ , Proteínas de Insetos/química , Proteínas de Insetos/genética , Chaperonas Moleculares/química , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , Sequências Repetitivas de Ácido Nucleico , Ribonucleoproteínas/química , Ribonucleoproteínas/genética
12.
Gene ; 154(2): 183-6, 1995 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-7890162

RESUMO

Using the murine cDNA that encodes Golgi alpha-mannosidase II (GlcNAc transferase I-dependent alpha 1,3[alpha 1,6] mannosidase; EC 3.2.1.114) as a probe to screen a cDNA library made from Drosophila melanogaster (Dm) embryos, we have isolated GmII, the Dm sequence homologue. The 3926-bp cDNA has an open reading frame of 3327 bp and predicts a polypeptide of approx. 127 kDa, a mass similar to that of the murine protein. The deduced mouse and Dm amino acid (aa) sequences share extensive similarity across their entire lengths and are both type-II transmembrane (TM) proteins with short cytoplasmic tails, single TM domains and large hydrophilic C-terminal domains. A region of approx. 200 aa, within the C-terminal domain, has considerable similarity to a corresponding region from several other alpha-mannosidases. GmII has been localized to a single site (85D14-18) on the right arm of chromosome 3.


Assuntos
Drosophila melanogaster/enzimologia , Drosophila melanogaster/genética , Genes de Insetos/genética , Hormônios de Inseto/genética , Manosidases/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Sequência Conservada , Hormônios de Inseto/química , Manosidases/química , Proteínas de Membrana/genética , Camundongos , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico
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