El desarrollo histórico del conocimiento sobre las disoluciones y su relación con la Teoría Cinético-Molecular : implicaciones didácticas.

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El modelado molecular y el laboratorio de ciencias naturales.

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Estudio citogenético-molecular del síndrome de Down : correlaciones genotipo-fenotipo en seis casos de síndrome de Down debidos a trisomía parcial del cromosoma 21.

Los casos de síndrome de Down debidos a trisomía parcial del cromosoma 21 se dan con una frecuencia muy baja. No por su rareza sino por su particularidad citogenética, estos casos aportan una información muy valiosa para el establecimiento de correlaciones entre el genotipo y el fenotipo. Estudiando el alcance citogenético de cada trisomía parcial y las características clínicas de la persona, se puede determinar qué regiones del cromosoma 21, cuando se encuentran en trisomía, son responsables de una determinada característica clínica. Mediante el estudio detallado de estos casos y estableciendo comparaciones entre ellos, se ha llegado a la construcción de un mapa fenotípico que asigna a las diferentes regiones del cromosoma 21, los diferentes rasgos clínicos del síndrome de Down. Se recoge el estudio citogenético y clínico de seis nuevos casos de síndrome de Down debidos a trisomía parcial del cromosoma 21, para contribuir a la construcción del mapa fenotípico; han permitido, además, ofrecer consejo genético a las familias.

La imagen molecular en el diagnóstico clínico por resonancia magnética.

Este artículo pertenece a un monográfico sobre química

La asimetría molecular y sus implicaciones en el entorno biológico.

Este artículo pertenece a un monográfico sobre química

Construcción de modelos en biología de COU : genética molecular.

Se presentan diversas formas de construir modelos de estructuras y procesos biológicos económicos, con materiales simples, para el apoyo audiovisual en las clases de biología., como la estructura del ADN, la replicación del ADN, la síntesis del m-ARN, la replicación del cromosoma bacteriano, la estructura del ARN-t y del nucleosoma, entre otros.

Biotecnología, genética molecular y cambio en la Educación : investigación de las necesidades educativas del profesorado de Biología y de nuevas propuestas curriculares en la Enseñanza Media y Universitaria.

Establecer las implicaciones educativas y políticas que conlleva la introducción de la Biotecnología, así como la respuesta Institucional dada hasta el momento comparándola con la situación en otros países. Investigar las necesidades de alumnos y profesores en estas materias. Desarrollar unas bases para una política educativa adecuada a este tema. Profesores y alumnos de EEMM y Universidad. A) Revisión teórica y estado actual. Revisa los siguientes aspectos: definiciones, áreas de aplicación e investigación, empresas e Instituciones vinculadas y situación en otros países. B) Necesidades y actitudes de alumnos y profesores. Aplicación de encuestas por correo. Obtienen información sobre los siguientes aspectos: aspectos didácticos y curriculares de la Biológica, recursos, necesidades de formación, actitudes y líneas de investigación. Estadísticas y documentos oficiales. 2 cuestionarios elaborados ad hoc (no incluídos en la memoria). A) Análisis teórico. B) Datos directos. C) Frecuencias. En primer lugar, se constata la dificultad de una definición única de Biotecnología, aunque los campos de aplicación son más claros. Por otro lado, un 6 de los investigadores nacionales se dedican a estos temas. Además el sector privado tiene cierta presencia. También se comentan los objetivos del programa movilizador sobre Biotecnología. Respecto a los currícula, subsisten problemas de definiciones de objetivos, aunque se aportan recomendaciones. En relación con los estudios de opinión efectuados, se observan tendencias homogéneas en relación con las horas dedicadas a materias básicas, contenidos, etc. Sin embargo, los contenidos aplicados y los más novedosos están poco representados. Por otro lado, un 60 por ciento de los profesores demandan formación en éstos, que son considerados como una revolución científico-técnica que debe incorporarse al currículum. A nivel mundial, la preocupación por la Enseñanza de la Biotecnología crece. Se han creado numerosos Organismos y Programas para introducirla en todos los niveles educativos. Respecto a las directrices más importantes, es necesario definir una política clara que reconozca la importancia de las nuevas tecnologías, elabore currícula y dote de los medios necesarios, que desarrolle un plan de perfeccionamiento de profesorado y fomente programas de investigación.

Molecular And Biochemical Characterization Of Caffeine Synthase And Purine Alkaloid Concentration In Guarana Fruit.

Guarana seeds have the highest caffeine concentration among plants accumulating purine alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of purine alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein.

On The Distinct Molecular Architectures Of Dipping- And Spray-lbl Films Containing Lipid Vesicles.

The introduction of spraying procedures to fabricate layer-by-layer (LbL) films has brought new possibilities for the control of molecular architectures and for making the LbL technique compliant with industrial processes. In this study we show that significantly distinct architectures are produced for dipping and spray-LbL films of the same components, which included DODAB/DPPG vesicles. The films differed notably in their thickness and stratified nature. The electrical response of the two types of films to aqueous solutions containing erythrosin was also different. With multidimensional projections we showed that the impedance for the DODAB/DPPG spray-LbL film is more sensitive to changes in concentration, being therefore more promising as sensing units. Furthermore, with surface-enhanced Raman scattering (SERS) we could ascribe the high sensitivity of the LbL films to adsorption of erythrosin.

Albumin Is Synthesized In Epididymis And Aggregates In A High Molecular Mass Glycoprotein Complex Involved In Sperm-egg Fertilization.

The epididymis has an important role in the maturation of sperm for fertilization, but little is known about the epididymal molecules involved in sperm modifications during this process. We have previously described the expression pattern for an antigen in epididymal epithelial cells that reacts with the monoclonal antibody (mAb) TRA 54. Immunohistochemical and immunoblotting analyses suggest that the epitope of the epididymal antigen probably involves a sugar moiety that is released into the epididymal lumen in an androgen-dependent manner and subsequently binds to luminal sperm. Using column chromatography, SDS-PAGE with in situ digestion and mass spectrometry, we have identified the protein recognized by mAb TRA 54 in mouse epididymal epithelial cells. The ∼65 kDa protein is part of a high molecular mass complex (∼260 kDa) that is also present in the sperm acrosomal vesicle and is completely released after the acrosomal reaction. The amino acid sequence of the protein corresponded to that of albumin. Immunoprecipitates with anti-albumin antibody contained the antigen recognized by mAb TRA 54, indicating that the epididymal molecule recognized by mAb TRA 54 is albumin. RT-PCR detected albumin mRNA in the epididymis and fertilization assays in vitro showed that the glycoprotein complex containing albumin was involved in the ability of sperm to recognize and penetrate the egg zona pellucida. Together, these results indicate that epididymal-derived albumin participates in the formation of a high molecular mass glycoprotein complex that has an important role in egg fertilization.

Molecular And Morphological Evidence Reveals A New Species In The Phyllomedusa Hypochondrialis Group (hylidae, Phyllomedusinae) From The Atlantic Forest Of The Highlands Of Southern Brazil.

The taxonomic status of a disjunctive population of Phyllomedusa from southern Brazil was diagnosed using molecular, chromosomal, and morphological approaches, which resulted in the recognition of a new species of the P. hypochondrialis group. Here, we describe P. rustica sp. n. from the Atlantic Forest biome, found in natural highland grassland formations on a plateau in the south of Brazil. Phylogenetic inferences placed P. rustica sp. n. in a subclade that includes P. rhodei + all the highland species of the clade. Chromosomal morphology is conservative, supporting the inference of homologies among the karyotypes of the species of this genus. Phyllomedusa rustica is apparently restricted to its type-locality, and we discuss the potential impact on the strategies applied to the conservation of the natural grassland formations found within the Brazilian Atlantic Forest biome in southern Brazil. We suggest that conservation strategies should be modified to guarantee the preservation of this species.

Effect Of Aloe Vera Application On The Content And Molecular Arrangement Of Glycosaminoglycans During Calcaneal Tendon Healing.

Although several treatments for tendon lesions have been proposed, successful tendon repair remains a great challenge for orthopedics, especially considering the high incidence of re-rupture of injured tendons. Our aim was to evaluate the pharmacological potential of Aloe vera on the content and arrangement of glycosaminoglycans (GAGs) during tendon healing, which was based on the effectiveness of A. vera on collagen organization previously observed by our group. In rats, a partial calcaneal tendon transection was performed with subsequent topical A. vera application at the injury site. The tendons were treated with A. vera ointment for 7 days and excised on the 7(th) , 14(th) , or 21(st) day post-surgery. Control rats received ointment without A. vera. A higher content of GAGs and a lower amount of dermatan sulfate were detected in the A. vera-treated group on the 14(th) day compared with the control. Also at 14 days post-surgery, a lower dichroic ratio in toluidine blue stained sections was observed in A. vera-treated tendons compared with the control. No differences were observed in the chondroitin-6-sulfate and TGF-β1 levels between the groups, and higher amount of non-collagenous proteins was detected in the A. vera-treated group on the 21(st) day, compared with the control group. No differences were observed in the number of fibroblasts, inflammatory cells and blood vessels between the groups. The application of A. vera during tendon healing modified the arrangement of GAGs and increased the content of GAGs and non-collagenous proteins.

Genetic Breeding And Diversity Of The Genus Passiflora: Progress And Perspectives In Molecular And Genetic Studies.

Despite the ecological and economic importance of passion fruit (Passiflora spp.), molecular markers have only recently been utilized in genetic studies of this genus. In addition, both basic genetic researches related to population studies and pre-breeding programs of passion fruit remain scarce for most Passiflora species. Considering the number of Passiflora species and the increasing use of these species as a resource for ornamental, medicinal, and food purposes, the aims of this review are the following: (i) to present the current condition of the passion fruit crop; (ii) to quantify the applications and effects of using molecular markers in studies of Passiflora; (iii) to present the contributions of genetic engineering for passion fruit culture; and (iv) to discuss the progress and perspectives of this research. Thus, the present review aims to summarize and discuss the relationship between historical and current progress on the culture, breeding, and molecular genetics of passion fruit.