Nematicidal activity of fervenulin isolated from a nematicidal actinomycete, Streptomyces sp. CMU-MH021, on Meloidogyne incognita

An isolate of the actinomycete, Streptomyces sp. CMU-MH021 produced secondary metabolites that inhibited egg hatch and increased juvenile mortality of the root-knot nematode Meloidogyne incognita in vitro. 16S rDNA gene sequencing showed that the isolate sequence was 99% identical to Streptomyces roseoverticillatus. The culture filtrates form different culture media were tested for nematocidal activity. The maximal activity against M. incognita was obtained by using modified basal (MB) medium. The nematicidal assay-directed fractionation of the culture broth delivered fervenulin (1) and isocoumarin (2). Fervenulin, a low molecular weight compound, shows a broad range of biological activities. However, nematicidal activity of fervenulin was not previously reported. The nematicidal activity of fervenulin (1) was assessed using the broth microdilution technique. The lowest minimum inhibitory concentrations (MICs) of the compound against egg hatch of M. incognita was 30 μg/ml and juvenile mortality of M. incognita increasing was observed at 120 μg/ml. Moreover, at the concentration of 250 μg/ml fervenulin (1) showed killing effect on second-stage nematode juveniles of M. incognita up to 100% after incubation for 96 h. Isocoumarin (2), another bioactive compound produced by Streptomyces sp. CMU-MH021, showed weak nematicidal activity with M. incognita

Integrated STEM in initial teacher education: Tackling diverse epistemologies

Science, Technology, Engineering, and Mathematics (STEM) each have distinct epistemological foundations for the production of knowledge, yet a recent international trend in education is to integrate these fields as an approach to teaching and learning. According to the literature, integrated STEM education involves concurrent teaching of two or more knowledge domains from the collection of traditional knowledge silos that constitute S.T.E.M.. The rationale for integrated STEM education is grounded in a perceived need to simulate the complexity of real-world situations, where examples of integrated STEM tend to evolve over time, through the need to solve problems in naturalistic contexts by teams of researchers with different disciplinary expertise. In educational settings, each school S.T.E.M. discipline has evolved with pedagogical responses to simulate real-world contexts such as science inquiry or mathematical problem solving, however, the notion of integrated STEM adds layers of complexity to pedagogical responses. Our aim in this chapter is to address this complexity from the perspective of integrated STEM in initial teacher education programs, based on critical reflections of our recent teaching experiences and learning experiences of our students. We explore the demands on initial teacher education STEM students in terms of the diversity of analytical epistemological orientations, and we consider possible strategies for understanding synthetic epistemological orientations that may inform better our understanding of learning through integrated STEM