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

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

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