Isolation and purification of an enzyme hydrolyzing ochratoxin A from aspergillus niger

Ochratoxin A is a mycotoxin produced by several Aspergillus and some Penicillium species which may be present in food and feed products. It can be enzymatically hydrolyzed into ochratoxin α and l-β-phenylalanine, thereby decreasing its toxicity. The ochratoxin A degradation capacity of Aspergillus niger is well known and here we report the isolation and purification of a novel enzyme from A. niger that hydrolyzes this mycotoxin. A wheat germ medium supplemented with ochratoxin A was used to produce the enzyme, which was purified from culture filtrate by acetone precipitation and anion exchange chromatography. An overall purification of 2.5-fold with a recovery of 68% and a final specific activity of 36 U/mg was obtained. The enzyme is a metalloenzyme as it was inhibited at 10 mM EDTA, whereas PMSF had no effect. The ochratoxin A hydrolytic enzyme presented a V max of 0.44 μM/min and a K m of 0.5 mM when the reaction was carried out at pH 7.5 and 37°C.Fundação para a Ciência e a Tecnologia (FCT

Engineering properties of tuffs in the Sandikli region (Afyon - Turkey) and their possible use as concrete aggregates

Sandikli is located in the western part of Central Anatolia in Turkey. Middle to Upper Miocene trachyandesitic, andesitic and phonolitic lavas, tuffs and tuffites are found in the study area. The tuffs are essentially vitritic and vitritic-crystal tuffs with varying proportions of pyroclasts, pyrogenetic and secondary minerals. In this study the engineering properties of Sandikli zeolithic tuffs and their possible use as concrete aggregate have been investigated. The 28 samples were examined to determine their physico-mechanical properties and their suitability as lightweight concrete. In particular, two materials were tested-with maximum size aggregates of 4 and 8 mm. The results indicate that tuffs from the Ballik, Sogucak and Sütlüce region can be used as light-weight concrete aggregates. Other tuffs can satisfactorily be used as plaster, while all the materials form acceptable building stone

Examining changes in preservice mathematics teachers’ technological pedagogical content knowledge from their microteaching

Microteaching is regarded as an effective method that allows preservice teachers to gain the experience of instructional processes and is used to improve teaching skills in an environment similar to a real classroom. Microteaching, which is utilized as a method for increasing the quality of a teacher’s education, is also used in research studies conducted within the scope of Technological Pedagogical Content Knowledge (TPCK). Accordingly, the purpose of this research is to observe changes in preservice teachers’ TPCK from their microteaching practices conducted under a conceptual TPCK framework. The participants are 52 third-year preservice teachers. An analysis was performed based on specific themes from the application, which had been developed to reveal the changes in preservice teachers’ conceptual framework of TPCK components. Content analysis was used to analyze the observation forms, self-evaluations, and transcriptions from the interviews on the self-evaluations for the effects over their procedural changes within the context of the themes. The study’s findings indicate that preservice teachers use the technological tools to attain what they had specified in their instructional plans. Also when considered in terms of the TPCK components, preservice teachers made remarkable progress. © 2017 EDAM

From epidemiology to treatment: Aspirin's prevention of brain and breast-cancer and cardioprotection may associate with its metabolite gentisic acid

Background: Epidemiological studies indicate that aspirin consumption reduces the risk of tumors, which is especially relevant for colonic adenoma and carcinoma. Similar observations were made for glial brain tumors and breast cancers, yet the results are inconsistent. Gentisic acid (GA) is a minor catabolite of aspirin; yet humans carrying CYP2C9-variants incapable to catabolize aspirin to GA do not benefit from aspirin in prevention against colonic adenoma. GA blocks binding of Fibroblastic Growth Factor to its receptor and its sulphonate metabolite dobesilic acid blocks growth of C6 glioblastoma in vivo. GA is also an endogenously produced siderophore in mammalians for the transport of iron, a trace element which stimulates tumor growth and enhances anthracycline cardiotoxicity