RESUMEN
The mammalian inducer of apoptosis Bax is lethal when expressed in yeast and plant cells. To identify potential inhibitors of Bax in plants we transformed yeast cells expressing Bax with a tomato cDNA library and we selected for cells surviving after the induction of Bax. This genetic screen allows for the identification of plant genes, which inhibit either directly or indirectly the lethal phenotype of Bax. Using this method a number of cDNA clones were isolated, the more potent of which encodes a protein homologous to the class theta glutathione S-transferases. This Bax-inhibiting (BI) protein was expressed in Escherichia coli and found to possess glutathione S-transferase (GST) and weak glutathione peroxidase (GPX) activity. Expression of Bax in yeast decreases the intracellular levels of total glutathione, causes a substantial reduction of total cellular phospholipids, diminishes the mitochondrial membrane potential, and alters the intracellular redox potential. Co-expression of the BI-GST/GPX protein brought the total glutathione levels back to normal and re-established the mitochondrial membrane potential but had no effect on the phospholipid alterations. Moreover, expression of BI-GST/GPX in yeast was found to significantly enhance resistance to H(2)O(2)-induced stress. These results underline the relationship between oxidative stress and Bax-induced death in yeast cells and demonstrate that the yeast-based genetic strategy described here is a powerful tool for the isolation of novel antioxidant and antiapoptotic genes.
Asunto(s)
Apoptosis/genética , Glutatión Transferasa/genética , Proteínas Proto-Oncogénicas/genética , Saccharomyces cerevisiae/genética , Secuencia de Aminoácidos , Supervivencia Celular/genética , Regulación Fúngica de la Expresión Génica , Glutatión Transferasa/metabolismo , Datos de Secuencia Molecular , Estrés Oxidativo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/metabolismo , Alineación de Secuencia , Proteína X Asociada a bcl-2RESUMEN
A study is carried out on 64 first grade school children for establishing the effect of computer training on the functional status of principally engaged systems with the purpose to determine the optimum duration of work with video terminal during the school day. The examinations are performed before and after computer lessons in mathematics and Bulgarian language in days with one and two lessons, and with the same subjects taught in the traditional way (control group). Traced are the changes in the accommodation, the eye rheobase, critical frequency of fusing the light flickers, resistance, volume and accuracy of the visual perception, static tremor and excretion of sodium and potassium in the saliva. The data point out to relatively higher pressure at work on video terminal in comparison with the traditional education. This imposes restriction in the duration of the lesson up to 20 minutes. The inclusion of second inconsistent computer lessons in the educational programme has no unfavourable effect on the functional status of the organism.
Asunto(s)
Instrucción por Computador/métodos , Glándulas Suprarrenales/fisiología , Sistema Nervioso Central/fisiología , Niño , Instrucción por Computador/instrumentación , Humanos , Examen Neurológico , Sistema Nervioso Simpático/fisiología , Pruebas de Visión , Visión Ocular/fisiologíaRESUMEN
An examination of 300 students was carried out, aged 9, 12 and 15, in the process of their training, aiming at the establishment of the characteristics of their reactivity to mental loading. Modern psychophysiological and biochemical methods were used in the dynamic follow up of the changes in CNS and neuroendocrine activity. Definite age and sex discrepancies were found, on the base of the analysis, in the CNS reactivity to mental loading. With the growing up, the volume and speed of the work performed were increased and their accuracy enhanced. The boys showed faster reactions and less accuracy at work. The girls were distinguished with a better characteristic of their capacity for work. The curves of the daily and weekly dynamics of mental capacity for work were outlined.
Asunto(s)
Desarrollo Infantil , Aprendizaje/fisiología , Procesos Mentales/fisiología , 17-Hidroxicorticoesteroides/orina , Adolescente , Niño , Epinefrina/orina , Femenino , Humanos , Masculino , Fatiga Mental , Salud Mental , Desempeño Psicomotor , Factores SexualesRESUMEN
A longitudinal study of development, reactivity and health state of the students from the initial course, trained during five- and six-day school week was carried out under conditions of full-day organization of the training-educational work. Deviations in the hygienic norms of some moments of daily regime, some results from the dynamics of working capacity and high neurotic morbidity with both forms of organization of trainingeducational work, necessitate essential corrections for its rationalization. Apart from all that, the parallel between the results from the examination of the students, trained during five- and six-day school week in the course of three school years, definitely indicate the following: better working capacity towards the end of school day and week, circulation, realized on a more rational base, better strength indices, lower moment somatic affection and acute morbidity, low number of often-sick-students and more completely healthy students, twice lower neurotic morbidity in favour of the students with a five-day school regime. The results obtained from the complex study, determine the effect of five-day school week on working capacity, development and health of the students to be more favourable from health-hygienic positions.