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Graduate teaching assistants (GTAs) play important instructional roles in introductory science courses, yet they often have little training in pedagogy. The most common form of teaching professional development (PD) for GTAs is a presemester workshop held at the course, department, or college level. In this study, we compare the effectiveness of presemester workshops at three northeastern research universities, each of which incorporated scientific teaching as the pedagogical content framework. The comparison of GTA PD program outcomes at three different institutions is intended to test theoretical assertions about the key role of contextual factors in GTA PD efficacy. Pretest and posttest surveys were used to assess changes in GTA teaching self-efficacy and anxiety following the workshops, and an objective test was used to assess pedagogical knowledge. Analysis of pretest/posttest data revealed statistically significant gains in GTA teaching self-efficacy and pedagogical knowledge and reductions in teaching anxiety across sites. Changes in teaching anxiety and self-efficacy, but not pedagogical knowledge, differed by training program. Student ratings of GTAs at two sites showed that students had positive perceptions of GTAs in all teaching dimensions, and relatively small differences in student ratings of GTAs were observed between institutions. Divergent findings for some outcome variables suggest that program efficacy was influenced as hypothesized by contextual factors such as GTA teaching experience.

Assesses the role of cytoplasmic polyadenylation element-binding protein (CPEB) in cytoplasmic polyadenylation. Isolation of the CPEB by affinity chromatography; Developmental expression of CPEB; Phosphorylation of CPEB during Xenopus oocyte maturation.

Meiotic progression in Xenopus oocytes, and all other oocytes investigated, is dependent on polyadenylation-induced translation of stockpiled maternal mRNAs. Early during meiotic resumption, phosphorylation of CPE-binding protein (CPEB) is required for polyadenylation-induced translation of mRNAs encoding cell cycle regulators. Xenopus Gef (XGef), a Rho-family guanine-exchange factor, influences the activating phosphorylation of CPEB. An exchange-deficient version of XGef does not, therefore implicating Rho-family GTPase function in early meiosis. We show here that Clostridium difficile Toxin B, a Rho-family GTPase inhibitor, does not impair early CPEB phosphorylation or progression to germinal vesicle breakdown, indicating that XGef does not influence these events through activation of a Toxin-B-sensitive GTPase. Using the inhibitors U0126 for mitogen-activated protein kinase (MAPK), and ZM447439 for Aurora kinase A and Aurora kinase B, we found that MAPK is required for phosphorylation of CPEB, whereas Aurora kinases are not. Furthermore, we do not detect active Aurora kinase A in early meiosis. By contrast, we observe an early, transient activation of MAPK, independent of Mos protein expression. MAPK directly phosphorylates CPEB on four residues (T22, T164, S184, S248), but not on S174, a key residue for activating CPEB function. Notably, XGef immunoprecipitates contain MAPK, and this complex can phosphorylate CPEB. MAPK may prime CPEB for phosphorylation on S174 by an as-yet-unidentified kinase or may activate this kinase. [ABSTRACT FROM AUTHOR]