Mutagenecity in the mal regions ofEscherichia coli

Résumé L'efficacité de la nitrosoguanidine (MNG) dans différents milieux de culture et tampons a été étudiée. Les résultats obtenus montrent qu'avec le temps, la fraction de cellules survivant au traitement diminue progressivement alors que la fréquence de mutation augmente dans tous les milieux. L'activité de cet agent atteint un maximum dans le milieu DM-glucose tandis que dans le tampon TM elle est à son plus bas niveau.     

Establishment of two mosquito cell lines from larval tissues ofAedes w-albus

Zusammenfassung Zwei neue Zellinien vonAedes w-albus, die seit der Isolation schon 27 bzw. 37mal kultiviert wurden, sind isoliert worden. Die Zellen konnten 45 Tage in flüssigem Stickstoff aufbewahrt werden, ohne ihre Vermehrungsfähigkeit einzubüssen.     

Ethanol influence on insulin secretion from isolated rat islets

Summary This study was done to delineate the role of - and -adrenergic receptors and cyclic AMP in the mechanism of ethanol effects on insulin release from isolated islets. Rats were given an -adrenergic blocker, phentolamine, or a -adrenergic blocker, propranolol. In addition, ethanol 1 g/kg was given intragastrically 1 h prior to sacrifice. Glucose mediated insulin release from isolated islets was enhanced by phentolamine and decreased by propranolol. Ethanol treatment inhibited glucose-induced insulin release from isolated islets of control rats as well as those given phentolamine and/or propranolol. Insulin release from isolated islets in response to dibutyryl-cyclic AMP was attenuated by ethanol. Theophylline enhanced glucose mediated insulin release from control islets but ethanol treatment produced a significant inhibition of insulin response. The data suggest that the site of action of the deleterious effects of ethanol on insulin release from isolated islets in rat does not involve adrenergic system and cyclic AMP.Supported by the U.S. Veterans Administration     

Genotype-specific reduction in methyl nitrosourea (MNU) induced sister chromatid exchanges (SCE) in vivo during aging

Summary We studied mice from five strains (BALB/c, C3H/HeSnJ, C57BL/6J, Cs^b and 129/ReJ) at two ages (young, 10±1 weeks; and old, 67±3 weeks) for the induction of sister chromatid exchanges (SCEs) in vivo by methyl nitrosourea (MNU). The SCE frequency is genotype-specific. The F₁ phenotype resembles the low responding parent. SCE induction is significantly lower in the older animals of each strain than their younger counterparts, and the reduction of SCE/cell with old age is strain-specific. A general explanation for these results must include strain differences in relative mutagenic sensitivity, genotype-specific pattern of reduction in DNA repair and other such factors affecting SCE formation, with old age.     

On the contribution of boundaries towards strength in oxygen free high conductivity copper subjected to repetitive upsetting–extrusion

Oxygen free high conductivity (OFHC) copper was subjected to 1, 5, 10, 15 and 20 cycles of repetitive upsetting and extrusion (RUE) process at room temperature. Microstructure and microhardness in the RUE processed material were evaluated at specific locations and correlated with the equivalent plastic strain. The microhardness of the material was found to be independent of strain or number of RUE cycles at certain locations whereas it exhibited strain softening behaviour at certain locations even though significant grain refinement was achieved. This difference in behaviour is attributed to the varied strength contribution from different types of boundaries present in the material after deformation.     

Microbiome,probiotics and neurodegenerative diseases: deciphering the gut brain axis

The gut microbiota is essential to health and has recently become a target for live bacterial cell biotherapies for various chronic diseases including metabolic syndrome, diabetes, obesity and neurodegenerative disease. Probiotic biotherapies are known to create a healthy gut environment by balancing bacterial populations and promoting their favorable metabolic action. The microbiota and its respective metabolites communicate to the host through a series of biochemical and functional links thereby affecting host homeostasis and health. In particular, the gastrointestinal tract communicates with the central nervous system through the gut–brain axis to support neuronal development and maintenance while gut dysbiosis manifests in neurological disease. There are three basic mechanisms that mediate the communication between the gut and the brain: direct neuronal communication, endocrine signaling mediators and the immune system. Together, these systems create a highly integrated molecular communication network that link systemic imbalances with the development of neurodegeneration including insulin regulation, fat metabolism, oxidative markers and immune signaling. Age is a common factor in the development of neurodegenerative disease and probiotics prevent many harmful effects of aging such as decreased neurotransmitter levels, chronic inflammation, oxidative stress and apoptosis—all factors that are proven aggravators of neurodegenerative disease. Indeed patients with Parkinson’s and Alzheimer’s diseases have a high rate of gastrointestinal comorbidities and it has be proposed by some the management of the gut microbiota may prevent or alleviate the symptoms of these chronic diseases.     

Oral and Written Reflection in Practice Management: An Action Research Approach

Reflection in Practice Management (PM) favoured the integrated approach where learners had to critically reflect on the study material, assessments and tasks throughout the year and to integrate their experiences in a meaningful manner that would demonstrate their development and learning over the year. Reflection in the form of portfolios focused on personal development and individual learning rather than on achieving a general set of course outcomes. But assessment of these portfolios revealed no real evidence of reflection or critical thinking. This study suggested that learners be assessed orally so that their reflections could come alive and so that the educator could learn from the assessment to restructure or re-curriculate where necessary. This study found that although the orals were not a preferred form of assessment, they contributed successfully to informing the written critical and reflective thinking in the portfolios. Using an action research approach, enabled us to not only address a fundamental problem that the educators and learners were battling with—how to encourage and indeed teach learners to think critically and to reflect, but it also showed the educators how to solve problems or seek solutions to didactic problems in their own classrooms. The recommendations in this paper may therefore inform courses other than PM that use reflective practice, critical thinking or portfolio assessments.     

Encouraging Intercultural Communication Using an Action Research Approach

South Africa is 15 years into democracy, but difficult dialogues about race, ethnicity, and other cultural differences are hindered when students are developmentally unprepared to handle them. Although institutions of learning have been painfully aware of the racial, cultural and ethnic divides on their campuses, no real strategies or policies have been put into place to ensure integration. This study started with problems that my colleagues in the Faculty of Science at a university in South Africa were experiencing with the lack of interaction and communication among the first year students in their large and diverse classrooms. They were also concerned that their students did not know how to deal with diversity and they wanted to graduate students who would be successful in their professional careers in a multicultural environment. This study found that using an action research approach was particularly successful in teaching Communication and in encouraging intercultural communication as lessons learned could be built upon or learned from in order to plan the next phase of intervention. The continual interactions during the various phases typical of the action research approach used, enabled the unearthing of feelings, problems and issues which would otherwise not have surfaced in the normal classroom where students are merely lectured. By transforming method and methodology, students and educators were exposed to new and different ways of being. This paper therefore reports on how a course in Communication was developed to facilitate communication and interaction between the different cultures and race groups in a Science classroom using an action research approach.