RESUMEN
To achieve an integrated understanding of the stem cell system of planarians at both the cellular and molecular levels, we developed a new method by combining "fluorescent activated cell sorting (FACS) index sorting" analysis and single-cell reverse transcription-polymerase chain reaction (RT-PCR) to detect the gene expression and cell cycle state of stem cells simultaneously. Single cells were collected using FACS, and cDNAs of each cell were used for semi-quantitative RT-PCR. The results were plotted on the FACS sorting profile using the "index sorting" function, which enabled us to analyze the gene expression in combination with cell biological data (such as cell cycle phase) for each cell. Here we investigated the adult stem cells of planarians using this method and obtained findings suggesting that the stem cells might undergo commitment during S to G2/M phase. This method could be a powerful and straightforward tool for examining the stem cell biology of not only planarians but also other organisms, including vertebrates.
Asunto(s)
Perfilación de la Expresión Génica , Planarias/citología , Células Madre/citología , Células Madre/metabolismo , Animales , División Celular/genética , Separación Celular/métodos , Análisis por Conglomerados , Femenino , Citometría de Flujo/métodos , Fase G2/genética , Genes de Helminto/genética , Proteínas del Helminto/genética , Hibridación in Situ , Masculino , Planarias/efectos de la radiación , Antígeno Nuclear de Célula en Proliferación/genética , Proyectos de Investigación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Fase S/genéticaRESUMEN
Planarians are attractive animals in which various questions related to the central nervous system (CNS) can be addressed, such as its origin and evolution, its degree of functional conservation among different organisms, and the plasticity and regenerative capabilities of neural cells and networks. However, it is first necessary to characterize at the gene expression level how this CNS is organized in intact animals. Previous studies have shown that the planarian brain can be divided into at least three distinct domains based on the expression of otd/Otx-related genes. In order to further characterize the planarian brain, we have recently isolated a large number of planarian neural-specific genes through DNA microarrays and ESTs projects. Here, we describe new molecular domains within the brain of intact planarians by the expression of 16 planarian neural-specific genes, including the putative homologues of protein tyrosine phosphatase receptor, synaptotagmin VII, slit, G protein and glutamate and acetylcholine receptors, by in situ hybridization in both whole-mount and transverse sections. Our results indicate that planarian otd/Otx-positive domains can be further subdivided into distinct molecular regions according to the expression of different neural genes. We found differences at the gene expression level between the dorsal and ventral sides of the brain, along its antero-posterior axis and also between the proximal and distal parts of the brain lateral branches. This high level of regionalization in the planarian brain contrasts with its apparent simplicity at the morphological level.