ABSTRACT
BACKGROUND: Five species of the genus Schistosoma, a parasitic trematode flatworm, are causative agents of Schistosomiasis, a disease that is endemic in a large number of developing countries, affecting millions of patients around the world. By using SAGE (Serial Analysis of Gene Expression) we describe here the first large-scale quantitative analysis of the Schistosoma mansoni transcriptome, one of the most epidemiologically relevant species of this genus. RESULTS: After extracting mRNA from pooled male and female adult-worms, a SAGE library was constructed and sequenced, generating 68,238 tags that covered more than 6,000 genes expressed in this developmental stage. An analysis of the ordered tag-list shows the genes of F10 eggshell protein, pol-polyprotein, HSP86, 14-3-3 and a transcript yet to be identified to be the five top most abundant genes in pooled adult worms. Whereas only 8% of the 100 most abundant tags found in adult worms of S. mansoni could not be assigned to transcripts of this parasite, 46.9% of the total ditags could not be mapped, demonstrating that the 3 sequence of most of the rarest transcripts are still to be identified. Mapping of our SAGE tags to S. mansoni genes suggested the occurrence of alternative-polyadenylation in at least 13 gene transcripts. Most of these events seem to shorten the 3 UTR of the mRNAs, which may have consequences over their stability and regulation. CONCLUSION: SAGE revealed the frequency of expression of the majority of the S. mansoni genes. Transcriptome data suggests that alternative polyadenylation is likely to be used in the control of mRNA stability in this organism. When transcriptome was compared with the proteomic data available, we observed a correlation of about 50%, suggesting that both transcriptional and post-transcriptional regulation are important for determining protein abundance in S. mansoni. The generation of SAGE tags from other life-cycle stages should contribute to reveal the dynamics of gene expression in this important parasite.
Subject(s)
Gene Expression Profiling/methods , Genes, Helminth , RNA, Helminth , Schistosoma mansoni/genetics , 3' Untranslated Regions , Animals , Female , Gene Expression Regulation , Male , Polyadenylation , RNA StabilityABSTRACT
RESUMO: Uma vez que uma droga tenha acesso ao corpo de um organismo, o mesmo desempenha um papel na determinação do espectro de efeitos bem como em sua intensidadee duração. A extensão com que uma droga pode ser absorvida e transportada a vários órgãos alvo influencia no seu perfil de potência e efeito. A variação genética pode potencialmente afetar a resposta individual à droga em vários passos. A absorção de uma droga e sua distribuição a vários órgãos são processos governados não apenas pelas propriedades físico-químicas da droga, mas também por moléculas endógenas. Muitos dos genes de suscetibilidade a doenças são também alvos de drogas e podem simultaneamente predispor os pacientes à doença bem como à resistência ao tratamento. A identificação de novas variantes para predisposição às doenças pode indicar novos alvos terapêuticos e novas vias no desenvolvimento de drogas e intervenções ambientais. Esta sistemática caracterização da natureza e da função do polimorfismogenético em enzimas metabolizadoras-chave e outros avanços na farmacogenética têm um amplo potencial para melhorar a escolha do medicamento apropriado e a correta dose paraqualquer paciente em particular. Nesse artigo, revisamos os achados em farmacogenética na Epilepsia e na Doença de Alzheimer.
Subject(s)
Humans , Epilepsy , Pharmacogenetics , Polymorphism, Genetic , Polymorphism, Single NucleotideABSTRACT
Neurocysticercosis is the most frequent parasitic infection of the CNS and the main cause of acquired epilepsy worldwide. Seizures are the most common symptoms of the disease, together with headache, involuntary movements, psychosis and a global mental deterioration. Absolute diagnostic criteria include the identification of cysticerci, with scolex, in the brain by MRI imaging. We demonstrate here, for the first time, that T. solium DNA is present in the cerebrospinal fluid of patients. The PCR amplification of the parasite DNA in the CSF enabled the correct identification of 29/30 cases (96.7 %). The PCR diagnosis of parasite DNA in the CSF may be a strong support for the diagnosis of neurocysticercosis.
Subject(s)
Antigens, Helminth/cerebrospinal fluid , DNA/cerebrospinal fluid , Neurocysticercosis , Taenia solium/genetics , Animals , Humans , Neurocysticercosis/cerebrospinal fluid , Neurocysticercosis/diagnosis , Neurocysticercosis/microbiology , Polymerase Chain Reaction/methods , Sensitivity and Specificity , Taenia solium/immunologyABSTRACT
A detailed genome mapping analysis of 213,636 expressed sequence tags (EST) derived from nontumor and tumor tissues of the oral cavity, larynx, pharynx, and thyroid was done. Transcripts matching known human genes were identified; potential new splice variants were flagged and subjected to manual curation, pointing to 788 putatively new alternative splicing isoforms, the majority (75%) being insertion events. A subset of 34 new splicing isoforms (5% of 788 events) was selected and 23 (68%) were confirmed by reverse transcription-PCR and DNA sequencing. Putative new genes were revealed, including six transcripts mapped to well-studied chromosomes such as 22, as well as transcripts that mapped to 253 intergenic regions. In addition, 2,251 noncoding intronic RNAs, eventually involved in transcriptional regulation, were found. A set of 250 candidate markers for loss of heterozygosis or gene amplification was selected by identifying transcripts that mapped to genomic regions previously known to be frequently amplified or deleted in head, neck, and thyroid tumors. Three of these markers were evaluated by quantitative reverse transcription-PCR in an independent set of individual samples. Along with detailed clinical data about tumor origin, the information reported here is now publicly available on a dedicated Web site as a resource for further biological investigation. This first in silico reconstruction of the head, neck, and thyroid transcriptomes points to a wealth of new candidate markers that can be used for future studies on the molecular basis of these tumors. Similar analysis is warranted for a number of other tumors for which large EST data sets are available.
Subject(s)
Gene Expression Profiling , Genetic Markers , Head and Neck Neoplasms/genetics , RNA, Messenger/genetics , Thyroid Neoplasms/genetics , Transcription, Genetic , Alternative Splicing , Expressed Sequence Tags , Head and Neck Neoplasms/metabolism , Humans , Larynx/metabolism , Mouth/metabolism , Pharynx/metabolism , Polymerase Chain Reaction , Protein Isoforms , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA , Thyroid Gland/metabolism , Thyroid Neoplasms/metabolismABSTRACT
O seqüenciamento de nosso genoma representa um passo essencial no entendimento da biologia humana e no planejamento racional de pesquisas biomédicas. Contudo, é importante notar que o seqüenciamento de um dado genoma é apenas uma parte de um complexo quebra-cabeças. A informação genética deve ser usada como um mapa, a partir do qual começamos a compreender a base das doenças e a importância da variação genética através da análise da complexidade e do comportamento das regiões reguladoras, genes e proteínas, funções gênicas e sistemas celulares. Apesar dos enormes esforços para identificar genes de susceptibilidade, os resultados de estudos de genética molecular de esquizofrenia até o momento têm sido modestos. O uso apropriado da genômica poderá ajudar imensamente na elucidação das causas da esquizofrenia, permitindo avaliar o papel de novos genes, das variações genéticas, das formas de splicing alternativo, das variações de expressão gênica e de vias metabólicas de interesse. A convergência de dados bioquímicos, de imagem, de neuroanatomia, farmacológicos, clínicos e genéticos permite prever que estamos muito próximos de uma melhor compreensão das bases biológicas da esquizofrenia. A disponibilidade desses avanços terá um enorme impacto na pesquisa desta doença.
Subject(s)
Humans , Schizophrenia , Genome, Human , Polymorphism, Genetic , ForecastingABSTRACT
Com o aumento da expectativa de vida, visto hoje em todo o planeta, um maior número de indivíduos alcança uma idade avançada em que a manifestação de doenças neurodegenerativas é mais freqüente. Entre essas, a doença de Alzheimer (DA) é a causa mais freqüente de demência. Os achados mais marcantes na DA, em cérebros de pacientes acometidos pela doença, são as placas senis, os emaranhados neurofibrilares e a extensa perda neuronal. No entanto, existe uma carência generalizada de marcadores biológicos preditivos ou com valor diagnóstico para a DA. Estudos de genética molecular permitiram identificar quatro genes consistentemente associados com o maior risco de desenvolvimento da doença: APP, apoE, PSEN1 e PSEN2. No entanto, inúmeros estudos apontam para papel importante de outros genes, fortalecendo a hipótese de uma doença poligênica e multifatorial. Neste sentido, novas abordagens de estudo têm um futuro promissor, podendo indicar uma vasta população de genes ou alterações moleculares que possam explicar o surgimento da doença, vindo a fornecer as bases para a compreensão da DA e também para o delineamento de novas e mais eficazes abordagens de tratamento ou prevenção da doença.
Subject(s)
Humans , Apolipoproteins E/analysis , Alzheimer Disease/genetics , Polymorphism, Genetic , Alzheimer Disease/prevention & control , Genetic Markers/genetics , Molecular Diagnostic TechniquesABSTRACT
Sabemos hoje que os polimorfismos no gene da apolipoproteína E (apoE) são importantes fatores de risco para o desenvolvimento da doença de Alzheimer (DA). O gene apoE humano, mapeado no braço longo do cromossomo 19 (19q13.2), codifica uma glicoproteína com 317 aminoácidos, a qual desempenha um papel fundamental para o catabolismo de componentes ricos em triglicérides no corpo humano. Em humanos, existem três alelos principais do gene apoE, decorrentes de apenas duas alterações no DNA, chamados de Upsilon2, Upsilon3 e Upsilon4. A identificação da variante Upsilon4 do gene apoE como o fator genético de risco mais comum para a DA de início tardio sugere que o colesterol deva ter um papel direto na patogênese da doença. Contudo, a simples presença do alelo apoE Upsilon4 não é necessária nem suficiente para causar DA; este alelo apenas aumenta o risco de o indivíduo vir a desenvolver a doença, indicando que existem outros fatores ambientais e genéticos importantes no desenvolvimento da mesma.
Subject(s)
Humans , Apolipoproteins E/genetics , Alzheimer Disease/genetics , Cholesterol , Risk Factors , Chromosomes, Human , Polymorphism, GeneticABSTRACT
Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets.
Subject(s)
Schistosoma mansoni/genetics , Transcription, Genetic , Animals , Chromosome Mapping , Expressed Sequence Tags , Genes, Helminth , Helminth Proteins/genetics , Humans , Molecular Sequence Data , Schistosoma mansoni/pathogenicity , Schistosoma mansoni/physiology , Schistosomiasis mansoni/parasitologyABSTRACT
Bipolar disorder (BPD) is characterised by episodes of excitement interspersed with periods of depression. The role of genetic factors in BPD is indicated by studies in monozygotic twins showing 40-70 % of concordance. Studies using genetic markers showed linkage of genes for affective disorders in different chromosome regions, emphasising the polygenic and multifactorial traits. The main goal of our research is to search non-synonymous SNPs (those that result in modifications in protein sequence) in genes that can be associated with psychiatric diseases as suggested by genomic mapping and/or by physiological function of the protein. Using DNA sequencing we could confirm a new non-synonymous SNP in the conservative domain of the ALOX12 gene (17p13.1), suggested by EST alignment. This SNP is an alteration from G to A that leads to a change of an arginine (A) to a glutamine in one of the most important domains of the protein. This SNP was evaluated by DNA sequencing in 182 patients with BPD and 160 control individuals. An increased presence of allele A among patients (60 % in controls and 73.1 % in cases; chi(2) = 6.581, P = 0.010; OR = 1.8095, 95 % CI = 1.1477-2.853) was found, suggesting an association of this polymorphism with the BPD in this Brazilian sample.
