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| Registros recuperados: 8.210 | |
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| Horng,Jorng-Tzong; Cho,Wen-Fu. |
| Repeat sequences are the most abundant ones in the extragenic region of genomes. Biologists have already found a large number of regulatory elements in this region. These elements may profoundly impact the chromatin structure formation in nucleus and also contain important clues in genetic evolution and phylogenic study. This study attempts to mine rules on how combinations of individual binding sites are distributed repeat sequences. The association rules mined would facilitate efforts to identify gene classes regulated by similar mechanisms and accurately predict regulatory elements. Herein, the combinations of transcription factor binding sites in the repeat sequences are obtained and, then, data mining techniques are applied to mine the association... |
| Tipo: Journal article |
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| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582000000300004 |
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| Jones,Phillip B.C.. |
| During the fall of 1998, three research groups announced that they had devised methods for obtaining human embryonic stem cells. Human stem cells are characterized by the ability to form many cell types, and the scientific community anticipates that the cells should be useful for the treatment of a wide variety of diseases. The dilemma is that human stem cell methodology can require, at least to some extent, research with human fetal tissue or research involving human embryos. Those opposed to federal funding of the former are concerned that the studies would support the "legitimacy" of abortion, while the latter is seen as prohibited under current law. The National Bioethics Advisory Committee has suggested that the federal government should fund both... |
| Tipo: Journal article |
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| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582000000100003 |
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| Spollansky,Tatiana C.; Pitta-Alvarez,Sandra I.; Giulietti,Ana M.. |
| Hairy root cultures of Brugmansia candida (Solanaceae), a South American plant which produces scopolamine and hyoscyamine, were exposed to different elicitors (jasmonic acid (JA) and aluminum chloride (AlCl3)) in order to increase their productivity and/or stimulate their liberation. Hairy roots of 19-day old cultures (exponential phase) were exposed to these elicitors for 24 and 48 hours. The effects on alkaloid accumulation and release into the medium were evaluated. JA was tested at 2.5 and 25 m g/ml. After 24 hours, JA promoted the release of hyoscyamine (~1200%) when the highest concentration was used. Therefore, the positive effects seen with JA could possibly be attributed in part to ethanol (EtOH), the solvent in which the acid was dissolved. At... |
| Tipo: Journal article |
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| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582000000100006 |
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| Rodríguez,Laura; Castro,Leonardo. |
| This is a review on some biological and ecological characteristics of the early life stages of myctophids that exemplify their adaptations to coastal upwelling zones and oceanic nearby areas. The approach has been, however, not to make an exhaustive list of all possible research subjects but, in a more pragmatic way, a) to identify relevant aspects that can be approached with currently available methods in the region and, b) through examples of studies published nationally and regionally, to stimulate future research in larval ecology in the Humboldt Current. Three major themes were assessed: taxonomy and systematics, population ecology and reproductive strategies and, ecophysiology of the early life stages. Among the former, we detected a lack of... |
| Tipo: Journal article |
Palavras-chave: Ichthyoplankton; Myctophids; Humboldt Current; Upwelling areas. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382000000200011 |
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| Salamanca,Marco A.; Camaño,Andrés; Jara,Bibiana; Rodríguez,Tatiana. |
| An extensive spatial survey metal content to study the spatial distribution of Cu, Pb and Zn concentration in nearshore waters of San Jorge Bay, along the coast of Antofagasta City, Chile was carried out located near the Atacama desert, which represent the largest populated urban settlement in northern Chile (~ 260,000 inhabitants). The coastal zone of this area is under an intensive use as discharge location of pollutants of different sources. Dissolved Cu varies between 0.97 to 1.65 mug l-1, in the southern part of the study area and in front of an industrial discharge, respectively. The dissolved Pb shows a narrow concentration range (0.019 to 0.029 mug l-1) and Zn content varies between 1.7 mug l-1 in the northern part of the study area to 2.0 mug l-1,... |
| Tipo: Journal article |
Palavras-chave: Trace metal distribution; Coastal waters; Desert areas. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382000000200009 |
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| Olabuenaga,Susana E.. |
| The defence against infections is the essential function of the immune system of all Vertebrates. Fish present an efficient and developed immunologic response and in the case of Teleosts, with some similarities to the higher vertebrates. It can be divided into two types: innate or non specific and adquired or specific, both with a humoral and cellular compartments. Their relative importance can change according to the age of fish and is always under the influence of different factors. The most relevant components are mentioned here. There are two factors in fishes which strongly influence the immune response and antibody production, seasonal changes and temperature. The main lymphoid organs are described here: the thymus, the kidney and the spleen, as well... |
| Tipo: Journal article |
Palavras-chave: Antigen; Antibody; Leukocytes; Phagocytosis; Lymphokines; Inflammation; Immunostimulants. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382000000200010 |
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| Iannacone,José; Alvariño,Lorena; Caballero,Cecilia; Sánchez,Javier. |
| La evaluación de riesgos ambientales por productos fitosanitarios es un componente de importancia en los estudios de impacto ambiental en el sector agrícola. Se evaluó la ecotoxicidad de los plaguicidas de suelo, lindano y clorpirifos, sobre la mortalidad del oligoqueto Limnodrilus hoffmeisteri (CL50 24h) y tres plantas, en las cuales se observaron los siguientes efectos subletales: germinación en Lactuca sativa (CI90 96h), crecimiento de raíz en Lycopersicon esculentum (CI50 96h) y clorosis, necrosis, ruptura y formación de hojas nuevas en la lenteja de agua, Lemna minor (CE50 48h). En ambos agroquímicos se observó en general el siguiente orden de ecotoxicidad decreciente: Lycopersicon Lemna Lactuca Limnodrilus. En los tres ensayos con plantas se observó... |
| Tipo: Journal article |
Palavras-chave: Ensayo ecotoxicológico; Evaluación de riesgos ambientales; Agroquímico; Lindano; Clorpirifos; Limnodrilus; Lemna; Lycopersicon; Lactuca. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382000000200003 |
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| Chiappa,Elizabeth; Rodríguez,Sharon; Bascuñán,Rossana. |
| Se estudió la manipulación y preferencia floral de Centris rodophthalma Pérez en 3 localidades de la IV Región de Chile, caracterizadas, principalmente, por representantes de la familia Fabaceae y condiciones ambientales estrictas que reducen el rango de recursos disponibles para la abeja. Se estimó la influencia de factores florales de 6 especies de plantas en la preferencia de C. rodophthalma, con el objeto de determinar el grado de correspondencia entre la morfología de la abeja y la elección de la flor, considerando: longitud de la lengua de la abeja; tamaño, diseño, color y estructura de la flor; profundidad de la corola; capacidad volumétrica de nectarios y medida del ángulo formado entre nectario y resto del estandarte. De estas variables, sólo las... |
| Tipo: Journal article |
Palavras-chave: Centris; Fabaceae; Interacción insecto-planta; Chile. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382000000200002 |
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| Registros recuperados: 8.210 | |
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