Shaping classroom social experiences through collaborative small-group discussions.

BACKGROUND: Students form interpersonal and intrapersonal classroom social experiences with peers. While diverse intervention programmes have been developed, few have integrated social-emotional learning into academic activities to maximize the potential for learning and development. AIMS: This study examined the effects of collaborative small-group discussions on students' classroom social experiences at the interpersonal and intrapersonal levels. SAMPLE: The study included 250 students (Mage = 10.98, female = 52%) and six teachers from 12 English language arts fifth-grade classrooms in two public schools in the United States. METHODS: Students were assigned to one of three conditions: Collaborative Social Reasoning (CSR), Read-Aloud (RA), or Regular Instruction (RI). Students in the CSR condition participated in recurrent collaborative small-group discussions about stories related to complex social-moral issues, including friendship, social exclusion, ethics of care, and responsibility. Students in the RA condition read the same stories without discussions. RESULTS: Collaborative Social Reasoning students were more socially accepted by peers and were less aggressive to others compared to students in the other conditions. RA students revealed more aggressive behaviour than other groups. In a post-intervention interview, CSR students reported improved communication and group work strategies, ability to maintain harmonious relationships, and class participation. A higher proportion of CSR students in the CSR than the other conditions reported experiencing positive change in classroom relationships. Teacher interviews were used in conjunction with student interviews to triangulate conclusions from qualitative interview data. CONCLUSION: Findings suggest effective ways to structure collaborative small-group discussions to foster positive classroom social experiences with peers.

Teacher Scaffolding of Social and Intellectual Collaboration in Small Groups: A Comparative Case Study.

This comparative case study features two small groups of students engaging in collaborative dialog about social issues. Based on social constructivist theories, the two groups were compared across three major components of the small groups system: social dynamics, intellectual collaboration, and teacher scaffolding. Our goal was to holistically analyze these small group processes to understand why some small groups were highly successful while others were not, even within the same intervention and with the same teacher. Successful groups were those in which all students were able to access the conversational floor, many ideas were considered, students were able to share ideas and discuss collaboratively, and students were able to raise multiple forms of social reasoning to support and explain ideas. Change in social reasoning essay scores prior to and after the intervention were also considered as evidence of group success. Results show that teacher scaffolding and existing student processes served to amplify one another reciprocally. The teacher heightened productive social norms when they were present, which then served to encourage productive intellectual collaboration. However, when productive group norms were not present, the teacher took increasing control over the group, which further hampered productive social and intellectual interactions.

Arabinose-induction of lac-derived promoter systems for penicillin acylase production in Escherichia coli.

Arabinose was shown to serve as an effective inducer for induction of the lac-derived promoters in Escherichia coli using penicillin acylase (PAC) as a model protein. Upon the induction with a conventional inducer, isopropyl-beta-d-thiogalactopyranoside (IPTG), for pac overexpression, which is regulated by the trc or (DE3)/T7 promoter, the production of PAC was limited by the accumulation of PAC precursors (proPAC) as inclusion bodies. Negative cellular responses, such as growth inhibition and cell lysis, were frequently observed, resulting in a low pac expression level and poor culture performance. Interestingly, these technical hurdles can be overcome simply through the use of arabinose as an inducer. The results indicate that arabinose not only induced the lac-derived promoter systems (i.e., trc and (DE3)/T7) for pac (or LL pac) overexpression but also facilitated the posttranslational processing of proPAC for maturation. However, the arabinose-inducibility appears to be host-dependent and becomes less observable in the strains with a mutation in the ara operon. The arabinose-inducibility was also investigated in the expression system with the coexistence of the trc promoter system regulating pac expression and another arabinose-inducible promoter system of araB regulating degP coexpression.

Cytoplasmic overexpression, folding, and processing of penicillin acylase precursor in Escherichia coli.

Penicillin acylase (PAC) precursor, proPAC, was overproduced in a soluble or insoluble form in the cytoplasm of Escherichia coli through the expression of the leader-less pac gene (ll-pac) devoid of the coding region for the signal peptide of PAC. Also, a portion of the overexpressed proPAC was further processed to form mature PAC, indicating that the posttranslational processing steps for PAC maturation can occur in both the periplasm and the cytoplasm of E. coli. The cultivation performance for ll-pac expression was limited by several factors, including (1) misfolding of proPAC, resulting in the aggregation of insoluble proPAC as inclusion bodies, (2) intracellular proteolysis, leading to the degradation of the overexpressed gene products, and (3) inefficient PAC maturation, limiting the formation of active PAC. The effect of coexpression of various cytoplasmic chaperones, including trigger factor, GroEL/ES, DnaK/J-GrpE, and their combinations, on ll-pac expression was investigated. Intracellular proteolysis of the overexpressed gene products could be prevented by coexpression of GroEL/ES. On the other hand, coexpression of trigger factor appeared to be able to facilitate the folding of soluble proPAC and to improve PAC maturation. The roles of trigger factor and GroEL/ES could be coordinated to significantly improve ll-pac expression performance. DnaK/J-GrpE had an effect for solublization of proPAC and perhaps, similar to trigger factor, for improving PAC maturation. The ll-pac expression performance was also significantly improved through the simultaneous coexpression of DnaK/J-GrpE and GroEL/ES. The results of the study suggest that the folding and/or processing of proPAC could be a major issue limiting the overproduction of PAC in E. coli and the bottleneck could be eliminated through the coexpression of appropriate chaperone(s).

Chaperone-mediated folding and maturation of the penicillin acylase precursor in the cytoplasm of Escherichia coli.

Expression of the leaderless pac gene (LL pac), which lacks the coding region for the signal peptide of penicillin acylase (PAC), in Escherichia coli was conducted. It was demonstrated that the PAC precursor, proPAC, can be produced and even processed to form mature PAC in the cytoplasm, indicating that the posttranslational processing steps for PAC maturation can occur in both the periplasm and the cytoplasm of E. coli. The outcome of proPAC folding and PAC maturation could be affected by several factors, such as inducer type, proPAC formation rate, and chaperone availability. Misfolding of proPAC in the cytoplasm could be partially resolved through the coexpression of cytoplasmic chaperones, such as trigger factor, GroEL/ES, or DnaK/J-GrpE. The three chaperones tested showed different extents of the effect on proPAC solublization and PAC maturation, and trigger factor had the most prominent one. However, the chaperone-mediated solublization of proPAC did not guarantee its maturation, which is usually limited by the first autoproteolytic step. It was observed that arabinose could act as an effective inducer for the induction of LL pac expression regulated by the lac-derived promoter system of trc. In addition, PAC maturation could be highly facilitated by arabinose supplementation and coexpression of trigger factor, suggesting that the coordination of chaperone systems with proper culture conditions could dramatically impact recombinant protein production. This study suggests that folding/misfolding of proPAC could be a major step limiting the overproduction of PAC in E. coli and that the problem could be resolved through the search for appropriate chaperones for coexpression. It also demonstrates the analogy in the issues of proPAC misfolding as well as the expression bottleneck occurring in the cytoplasm (i.e., LL pac expression) and those occurring in the periplasm (i.e., wild-type pac expression).