461 research outputs found

    Gene polymorphisms for elucidating the genetic structure of the heavy-metal hyperaccumulating trait in Thlaspi caerulescens and their cross-genera amplification in Brassicaceae.

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    Genetic polymorphism was investigated in Thlaspi caerulescens J. & C. Presl at 15 gene regions, of which seven have been identified to putatively play a role in heavy-metal tolerance or hyperaccumulation. Single nucleotide and length polymorphisms were assessed at four cleaved amplified polymorphic sequences (CAPS) and 11 simple sequence repeat (microsatellite) loci, respectively. The utility of these loci for genetic studies in T. caerulescens was measured among seven natural populations (135 individuals). Fourteen loci rendered polymorphism, and the number of alleles per locus varied from 2 to 5 and 1 to 27 for CAPS and microsatellites, respectively. Up to 12 alleles per locus were detected in a population. The global observed heterozygosity per population varied between 0.01 and 0.31. Additionally, cross-species/genera amplification of loci was investigated on eight other Brassicaceae (five individuals per population). Overall, 70% of the cross-species/genera amplifications were successful, and among them, more than 40% provided intraspecific polymorphisms within a single population. This indicates that such markers may, as well, allow comparative population genetic or mapping studies between and within several Brassicaceae, particularly for genes involved in traits such as heavy-metal tolerance and/or hyperaccumulation

    Gene polymorphisms for elucidating the genetic structure of the heavy-metal hyperaccumulating trait in Thlaspi caerulescens and their cross-genera amplification in Brassicaceae

    Get PDF
    Genetic polymorphism was investigated in Thlaspi caerulescens J. & C. Presl at 15 gene regions, of which seven have been identified to putatively play a role in heavy-metal tolerance or hyperaccumulation. Single nucleotide and length polymorphisms were assessed at four cleaved amplified polymorphic sequences (CAPS) and 11 simple sequence repeat (microsatellite) loci, respectively. The utility of these loci for genetic studies in T. caerulescens was measured among seven natural populations (135 individuals). Fourteen loci rendered polymorphism, and the number of alleles per locus varied from 2 to 5 and 1 to 27 for CAPS and microsatellites, respectively. Up to 12 alleles per locus were detected in a population. The global observed heterozygosity per population varied between 0.01 and 0.31. Additionally, cross-species/genera amplification of loci was investigated on eight other Brassicaceae (five individuals per population). Overall, 70% of the cross-species/genera amplifications were successful, and among them, more than 40% provided intraspecific polymorphisms within a single population. This indicates that such markers may, as well, allow comparative population genetic or mapping studies between and within several Brassicaceae, particularly for genes involved in traits such as heavy-metal tolerance and/or hyperaccumulatio

    Self-efficacy enhanced in a cross-cultural context through an initiative in under-resourced schools in KwaZulu-Natal, South Africa

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    This paper discusses the Khanyisa Programme, an initiative in KwaZulu-Natal, South Africa, where learners from under-resourced schools are supported by teachers and high achievers in Grade 11 and 12 from a previously advantaged state school under apartheid. A qualitative, evaluative study was undertaken to identify key elements in the ongoing success of the programme and collect participant suggestions for improvement. The findings, discussed within the framework of self-efficacy theory, identified enormous gains by Khanyisa learners, leading to vastly improved career prospects

    Unlocking the grid: Language-in-education policy realisation in post-apartheid South Africa

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    This paper reflects on the state of educational language policy two decades into a postApartheid South Africa caught between official multilingualism and English. The focus is on the national language-in-education policy (LiEP) that advocates additive bi/multilingualism, and a provincial counterpart, the language transformation plan (LTP). Using Ricento and Hornberger’s onion metaphor, the paper seeks to uncover the meanings of policy realisation in education at legislative, institutional, and interpersonal levels. The LiEP’s non-realisation at institutional level is indexed by a ‘gridlock of collusion’ (Alexander, personal communication) between political elites and the majority of African-language speakers, who emulatively seek the goods that an English-medium education promises. To illustrate how teachers can become policy advocates, data are presented from a bilingual education in-service programme that supported the LTP. The paper argues that sociolinguistic insights into speakers’ heteroglossic practices should be used to counter prevailing monoglossic policy discourses and school language practices, and that all languages should be used as learning resources. Strategic essentialism would recognise the schooling system’s need to separately classify language subjects and to identify the languages most productively used for teaching across the curriculum. The paper concludes with a call for the revision of the LiEP
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