Structural organization of the gene for human CD36 glycoprotein

The cell-surface glycoprotein CD36 interacts with a large variety of ligands, including collagen types I and IV, thrombospondin, erythrocytes parasitized with Plasmodium falciparum, platelet-agglutatinating protein p37, oxidized low density lipoprotein, and long-chain fatty acids. Its expression is restricted to platelets, monocytes, adipocytes, and some endothelial and epithelial cells and is regulated during cell activation, differentiation, and development. CD36 belongs to a novel gene family of structurally related glycoproteins that includes CLA-1 and the lysosomal membrane glycoprotein LIMPII. To advance our knowledge on the genomic organization and the regulation of the cellular expression of the genes of this family, we have investigated the structural organization of the human CD36 gene and of its 5’-proximal flanking region. The CD36 gene is encoded by 15 exons that extend more than 32 kilobases on the human genome. Interestingly, the CD36 mRNA 5’-untranslated region is encoded by three exons. The 3’-untranslated region is contained in two exons, whose expression pattern can originate two mRNA forms. The cytoplasmic and transmembrane regions predicted at both terminal ends of the polypeptide chain are encoded by single exons, while the extracellular domain is encoded by 11 exons. The transcription initiation site of the CD36 gene is located 289 nucleotides upstream from the translational start codon. Sequence analysis of the proximal 5’-flanking region of the gene reveals the existence of a TATAbox appropriately located with respect to the transcription initiation site and several potential cis-regulatory elements that might contribute to the transcriptional regulation of the CD36 gene. Delineation of the structural organization of the CD36 gene may help in defining the boundaries of relevant structural and/or functional domains in CD36 and, by extension, in the other members of the family.Ministerio de Educación y Ciencia, Becas predoctorales en España, Promoción general del conocimiento

Marfiles Coptos en Valdetorres de Jarama (Madrid)

Presentación de un conjunto de marfiles tallados procedentes de la villa de Valdetorres de Jarama (provincia de Madrid). Resultan ser todos ellos piezas d e importación procedentes de Egipto, y fechables entre fines del siglo IV y la primera mitad del V d.C. Con ellos. pueden reconstruirse hipotéticamente cofres o paneles decorativos

Decreased responsiveness of basal gluconeogenesis to insulin action in hepatocytes isolated from genetically obese (fa/fa) Zucker rats

In vivo studies have demonstrated that hepatic glucose production is poorly responsive to insulin in genetically obese Zucker rats. In this work, we have investigated the modulation by insulin of basal gluconeogenesis, fructose 2,6-bisphosphate levels, and pyruvate kinase and 6-phosphofructo 2-kinase activities in hepatocytes isolated from fed obese (fa/fa) or lean (Fa/-) rats. Gluconeogenesis was estimated by the conversion of a mixture of [14C]lactate-pyruvate to [14C]glucose. Basal gluconeogenesis was significantly reduced in hepatocytes isolated from obese rats compared to that measured in hepatocytes from lean animals (0.63 +/- 0.09 vs. 1.47 +/- 0.05 mumol lactate converted to glucose/g cells.20 min; n = 3-4; P < 0.001). In hepatocytes isolated from lean rats, insulin, without affecting the cellular cAMP concentration, caused a dose-dependent inhibition of the rate of gluconeogenesis, which was accompanied by a significant increase in fructose 2,6-bisphosphate levels and activation of both pyruvate kinase and 6-phosphofructo 2-kinase. In contrast, in hepatocytes isolated from obese (fa/fa) rats, neither basal gluconeogenesis nor any of the other metabolic parameters mentioned were significantly modified by insulin, even when assayed at high hormonal concentrations (10 nM). These results demonstrate a lack of responsiveness of hepatic gluconeogenesis to short term insulin action in genetically obese (fa/fa) rats

Gene encoding the collagen type I and thrombospondin receptor CD36 is located on chromosome 7q11.2

The human CD36 is a member of a gene family of structurally related glycoproteins and functions as a receptor for collagen type I and thrombospondin. CD36 also binds to red blood cells infected with the human malaria parasite Plasmodium falciparum. In the present study, the CD36 gene was assigned to chromosome 7 by using the polymerase chain reaction with DNA from human-hamster somatic cell hybrids. Furthermore, the use of a CD36 genomic probe has allowed the localization of the CD36 locus to the 7q11.2 band by fluorescence in situ hybridization coupled with GTG-banding

La lateralización hemisférica de funciones como proceso mediador del aprendizaje en el aula

Respectivamente, en los cursos y programas de hábitos y técnicas de estudio, se viene diciendo que la mejor forma para conseguir la máxima retención de cualquier tipo de información, conlleva la utilización simultánea del mayor número de procesos sensoriales durante el período de memorización (Hemández Pina, 1990). Esto implicaría la necesidad de estudiar los contenidos teóricos y prácticos de las diferentes materias del currículum escolar desde la perspectiva del análisis de patrones estimulares complejos. Ni que decir tiene que, en última instancia, la función de reconocimiento e integración de la información contenida en estos estímulos complejos, correspondería al sujeto y, más específicamente, sería el resultado de la interacción ambiente-organismo, facilitada, concretamente, por la funcionalidad de las áreas corticales secundarias y terciarias de nuestro cerebro. Por otra parte, el estudio realizado por el alumno de los contenidos propios de una materia escolar, suele ir procedido de una explicación que con anterioridad el profesor realizó en el aula. Llegados a este punto, debemos hacemos la siguiente pregunta: ¿nuestro modelo educativo, correspondiene al segundo ciclo de E. G. B. y B. U. P., facilita la estimulación atencional de los diferentes procesos sensoriales del alumno/a en el aula? Dicho de otra forma, ¿estimulan los profesores la atención de sus alumnos atendiendo a la varibilidad individual existente en su aula? La experiencia nos dice que, generalmente, no

Effect of streptozotocin diabetes on the glycolytic flux and on fructose 2,6-bisphosphate levels in isolated rat enterocytes

In epithelial cells isolated from rat small intestine and incubated in the presence of 1 mM glucose, streptozotocin-induced diabetes reduced, by 46 and 29%, respectively, the rates of both glucose utilization and L-lactate formation. These effects were accompanied by a significant decrease of enterocyte fructose 2,6-bisphosphate concentration (about 50%) and of the glycolytic flux through the reaction catalyzed by 6-phosphofructo 1-kinase. The diminution of enterocyte fructose 2,6-bisphosphate levels caused by diabetes occurred in spite of an increase of hexose 6-phosphate concentration, and was associated with a reduction in the amount of active form of 6-phosphofructo 2-kinase; total activity of this enzyme was not significantly modified. Diabetes also caused an acceleration in the rate of 3-O-methyl-D-(14C) glucose uptake and increased hexokinase activity in enterocytes. Lactate dehydrogenase, pyruvate kinase and 6-phosphofructo 1-kinase activities were not found to be significantly different in epithelial cells isolated from control or diabetic animals. Our results indicate that a reduction of the glycolytic flux in enterocytes could collaborate to increase intestinal glucose absorption in the diabetic state

La política exterior yugoslava entre 1941 y 1953 : génesis y desarrollo del conflicto soviético-yugoslavo

La política exterior yugoslava entre 1941 y 1953: génesis y desarrollo del conflicto soviético-yugoslav

La melatonina y las nitronas como posibles agentes terapéuticos para el accidente cerebrovascular

El accidente cerebrovascular es una enfermedad del envejecimiento que afecta a millones de personas en todo el mundo, y el activador de plasminógeno de tipo tisular recombinante (r-tPA) es el único tratamiento aprobado. Sin embargo, el r-tPA tiene una ventana terapéutica baja y efectos secundarios que limitan su resultado beneficioso, lo que impulsa la búsqueda de nuevas terapias más eficientes. Entre ellos, la neuroprotección basada en melatonina o nitronas, como trampas de radicales libres, ha surgido como candidatos a medicamentos debido a su fuerte poder antioxidante. En este artículo de Perspectiva , se presenta una actualización de los resultados específicos de la melatonina y varias nitronas nuevas