A Novel Role for Mc1r in the Parallel Evolution of Depigmentation in Independent Populations of the Cavefish Astyanax mexicanus

The evolution of degenerate characteristics remains a poorly understood phenomenon. Only recently has the identification of mutations underlying regressive phenotypes become accessible through the use of genetic analyses. Focusing on the Mexican cave tetra Astyanax mexicanus, we describe, here, an analysis of the brown mutation, which was first described in the literature nearly 40 years ago. This phenotype causes reduced melanin content, decreased melanophore number, and brownish eyes in convergent cave forms of A. mexicanus. Crosses demonstrate non-complementation of the brown phenotype in F2 individuals derived from two independent cave populations: Pachón and the linked Yerbaniz and Japonés caves, indicating the same locus is responsible for reduced pigmentation in these fish. While the brown mutant phenotype arose prior to the fixation of albinism in Pachón cave individuals, it is unclear whether the brown mutation arose before or after the fixation of albinism in the linked Yerbaniz/Japonés caves. Using a QTL approach combined with sequence and functional analyses, we have discovered that two distinct genetic alterations in the coding sequence of the gene Mc1r cause reduced pigmentation associated with the brown mutant phenotype in these caves. Our analysis identifies a novel role for Mc1r in the evolution of degenerative phenotypes in blind Mexican cavefish. Further, the brown phenotype has arisen independently in geographically separate caves, mediated through different mutations of the same gene. This example of parallelism indicates that certain genes are frequent targets of mutation in the repeated evolution of regressive phenotypes in cave-adapted species

Determining the perceptions of teacher candidates on the concepts of science course, science laboratory, science teacher and science student via metaphors

The purpose of this study is to determine the perceptions of teacher candidates on the concepts of science course, science laboratory, science teacher and science student using metaphors. In this study, the phenomenological research method was used. The participants consisted of a total of 58 first year students who are studying at the department of Science Education at a state university located in the Eastern Black Sea Region in Turkey. The data of the study was obtained by asking the students to complete the sentences “a science course is like …, because …”, “a science laboratory is like …, because …”, “a science teacher is like …, because …” and “a science student is like …, because…”. In this study which used the research design of phenomenology in the scope of a qualitative research approach, the obtained data was analyzed using the method of content analysis. The most frequently mentioned metaphors in the study by the teacher candidates were “life” for the concept of science course, “fun” for the concept of science laboratory, “mother” for the concept of science teacher and “dough” for the concept of science student. According to the results of the study, it was observed that most teacher candidates perceived the concept of science course as “understanding/discovering life (26.3%) and infinite (21%)”, the concept of science laboratory as “a place that provides experience (22.7%) and entertainment (22.6%)”, the concept of science teacher as “mentor (25%)” and the concept of science student as “a valuable being (20%)”. It was also observed that the perceptions of the teacher candidates on science were generally positive. © 2018, International Journal of Research in Education and Science. All rights reserved

9 TH Grade Students' Mental Models about the Sound Concept

ABSTRAC

Determining the perceptions of teacher candidates on the concepts of science course, science laboratory, science teacher and science student via metaphors

The purpose of this study is to determine the perceptions of teacher candidates on the concepts of science course, science laboratory, science teacher and science student using metaphors. In this study, the phenomenological research method was used. The participants consisted of a total of 58 first year students who are studying at the department of Science Education at a state university located in the Eastern Black Sea Region in Turkey. The data of the study was obtained by asking the students to complete the sentences “a science course is like …, because …”, “a science laboratory is like …, because …”, “a science teacher is like …, because …” and “a science student is like …, because…”. In this study which used the research design of phenomenology in the scope of a qualitative research approach, the obtained data was analyzed using the method of content analysis. The most frequently mentioned metaphors in the study by the teacher candidates were “life” for the concept of science course, “fun” for the concept of science laboratory, “mother” for the concept of science teacher and “dough” for the concept of science student. According to the results of the study, it was observed that most teacher candidates perceived the concept of science course as “understanding/discovering life (26.3%) and infinite (21%)”, the concept of science laboratory as “a place that provides experience (22.7%) and entertainment (22.6%)”, the concept of science teacher as “mentor (25%)” and the concept of science student as “a valuable being (20%)”. It was also observed that the perceptions of the teacher candidates on science were generally positive. © 2018, International Journal of Research in Education and Science. All rights reserved

Behaviour of the model surface strip footing on reinforced sand

419-426A series of tests were carried out with an eccentrically loaded model surface strip footing on un-reinforced and reinforced dense sand to investigate the behaviour of the footing (decrease in ultimate load with increasing eccentricity, failure surfaces and load displacement relations). The experimental set-up used to run the tests consists of tank, model footing, sand and loading mechanism. A single woven geotextile strip sheet was placed horizontally below the footing’s base at a depth half of the footing’s width. The primary failure surfaces occurred at the eccentricity side for this laterally unrestricted footing. The use of this reinforcement increased the ultimate load by about 50% for centrally loaded strip footing in comparison with un-reinforced case and its contribution to ultimate load decreased as eccentricity increased in these conditions. Geotextile not only increased ultimate load, but also increased necessary amount of vertical displacement of footing to reach failure compared with un-reinforced case. The experimental results are in good agreement with Meyerhof’s effective width concept than the customary analysis and the customary analysis is unsafe outside the core

Teacher Educators' Views of "Model" Concept and Their Mental Models

UNAL, SUAT/0000-0002-0495-8385WOS: 000347033100008The aim of this study is to reveal teacher educators' views of model and also to determine their mental models about it. Phenomenographic research design has been carried out in this study. The sample of study consists of 14 teacher educators from education faculties of different universities in Turkey. Semi-structured interviews that consisted of 7 questions were used to collect data. Besides, sample was asked draw a concept map on "model" in the last interview question. Results have shown that teacher educators give similar responses including unqualified explanations to the interview questions related to the definition of model, characteristics of them, and the objectives of using models. It can also be asserted, that teacher educators do not have scientific understanding on the modeling process. The analyses of their responses to the interview questions and their concept maps have shown that most of the teacher educators in the sample have proximate or goal oriented mental models of the "model". Considering the results, it is suggested that teacher educators should not only follow the new theories, methods, or the applications in related literature theoretically, but also employ different theories, methods, or applications such as models and modeling in their courses