How to use polarity thinkingTM to manage tensions between accountability and learner agency when using a multipurpose portfolio?

Portfolios are often implemented to target multiple purposes, e.g. assessment, accountability and/or self-regulated learning. However, in educational practice, it appears to be difficult to combine different purposes in one portfolio, as interdependencies between the purposes can cause tensions. This paper explored directions to manage tensions that are inextricably linked to multipurpose portfolio use. We used a systems thinking methodology, that was based on the polarity thinkingTM framework. This framework provides a step-by-step approach to chart a polarity map® that can help to balance the tensions present in specific settings. We followed the steps of the framework to chart a polarity map for multipurpose portfolio use. Based on literature and our prior research, we selected one overarching polarity: accountability and learner agency. This polarity seems responsible for multiple tensions related to multipurpose portfolio use. We formulated values (potential benefits) and fears (tensions that can arise) of the two poles of this polarity. Then, we organised a session with stakeholders who work with the portfolio of the Dutch General Practice speciality programme. Together we formulated action steps and early warnings that can help to balance accountability and learner agency during multipurpose portfolio use. In addition to previous recommendations concerning portfolio use, we advocate that it is important to create a shared frame of reference between all involved with the multipurpose portfolio. During this process, the acknowledgement and discussion of tensions related to multipurpose portfolio use are vital.

Two differentially expressed MATE factor genes from apple complement the Arabidopsis transparent testa12 mutant.

Proanthocyanidins (PAs) are a class of flavonoids with numerous functions in plant ecology and development, including protection against microbial infection, animal foraging and damage by UV light. PAs are also beneficial in the human diet and livestock farming, preventing diseases of the cardiovascular system and lowering the risk of cancer, asthma and diabetes. Apples (Malus x domestica Borkh.) are naturally rich in flavonoids, but the flavonoid content and composition varies significantly between cultivars. In this work, we applied knowledge from the model plant Arabidopsis thaliana, for which the main features of flavonoid biosynthesis have been elucidated, to investigate PA accumulation in apple. We identified functional homologues of the Multidrug And Toxic compound Extrusion (MATE) gene TRANSPARENT TESTA12 from A. thaliana using a comparative genomics approach. MdMATE1 and MdMATE2 were differentially expressed, and the function of the encoded proteins was verified by complementation of the respective A. thaliana mutant. In addition, MdMATE genes have a different gene structure in comparison to homologues from other species. Based on our findings, we propose that MdMATE1 and MdMATE2 are vacuolar flavonoid/H(+) -antiporters, active in PA accumulating cells of apple fruit. The identification of these flavonoid transporter genes expands our understanding of secondary metabolite biosynthesis and transport in apple, and is a prerequisite to improve the nutritional value of apples and apple-derived beverages.

Characterization of tt15, a novel transparent testa mutant of Arabidopsis thaliana (L.) Heynh.

The Arabidopsis thaliana seed coat typically has a brown color due to the accumulation of flavonoid pigments in the testa. Mutants of A. thaliana with defects in pigment biosynthesis often produce seeds that are olive brown or even yellow in appearance, and the responsible genetic loci are referred to as TRANSPARENT TESTA (TT). Large-scale screening for mutants affected in seed development and complementation analysis of a candidate mutant line with all published A. thaliana tt mutants identified a new tt locus designated tt15. The tt15 mutation maps to the lower part of chromosome 1. Mutant plants produced pale greenish-brown seeds whose dormancy was slightly reduced. The phenotype was consistent with the maternal origin of the testa. Analysis of pigment accumulation and the study of expression patterns of genes involved in flavonoid biosynthesis in tt15 plants and seeds indicated a seed-specific phenotype. Most notable was a reduction of the cyanidin and quercetin content of tt15 seeds.

Knock-out mutants from an En-1 mutagenized Arabidopsis thaliana population generate phenylpropanoid biosynthesis phenotypes.

A collection of 8,000 Arabidopsis thaliana plants carrying 48,000 insertions of the maize transposable element En-1 has been generated. This population was used for reverse genetic analyses to identify insertions in individual gene loci. By using a PCR-based screening protocol, insertions were found in 55 genes. En-1 showed no preference for transcribed or untranscribed regions nor for a particular orientation relative to the gene of interest. In several cases, En-1 was inserted within a few kilobases upstream or downstream of the gene. En-1 was mobilized from such positions into the respective gene to cause gene disruption. Knock-out alleles of genes involved in flavonoid biosynthesis were generated. One mutant line contained an En-1 insertion in the flavonol synthase gene (FLS) and showed drastically reduced levels of kaempferol. Allelism tests with other lines containing En-1 insertions in the flavanone 3-hydroxylase gene (F3H) demonstrated that TRANSPARENT TESTA 6 (TT6) encodes flavanone 3-hydroxylase. The f3h and fls null mutants complete the set of A. thaliana lines defective in early steps of the flavonoid pathway. These experiments demonstrate the efficiency of the screening method and gene disruption strategy used for assigning functions to genes defined only by sequence.