Background:In an increasingly globalized world, the call for internationally comparable competence measurements has emerged. After several international studies on pre-college education, the focus has shifted to international assessments of vocational education and training (VET). VET researchers in Germany developed a computerbased test (ALUSIM) that measures the competence of German apprentices in internationally defined core commercial areas. Our own study deals with the adaptation of this test to Switzerland and a discussion of the challenges involved, with the aim of providing guidance for future adaptations. More specifically, despite commonalities between the German and Swiss VET systems, it is necessary to examine whether the contents and technical aspects of ALUSIM are appropriate for Swiss conditions in order to ensure validity and evidence based on test content. Methods:Several methods were used to examine the criteria context, construct, and IT components of the German computer-based test ALUSIM in order to successfully adapt it for Swiss commercial VET. To this end we first analyzed and compared the German and Swiss commercial VET systems and commercial curricula (context) to assess whether the tasks of the test were also embedded in the Swiss curriculum and whether any specific Swiss commercial contents were not represented by the test. Second, we interviewed experts in the commercial area to learn more about representative commercial job requirements (construct). Finally, we interviewed apprentices and tested our initial adaptation of ALUSIM to the Swiss context in order to assess the test's IT requirements.
In most species, elaborate programs exist to protect chromatin and maintain its integrity over cell cycles and generations. However, some species systematically undergo excision and elimination of portions of their genome in somatic cells in a process called programmed-DNA elimination (PDE). PDE involves the elimination of mainly repeated elements but also protein-coding genes. PDE has been described in approximately 100 species from very distinct phyla, and more extensively in the parasitic nematodes Ascaris and in the unicellular Ciliates. In Ciliates, where PDE is pervasive, the underlying mechanisms have been studied and involve small RNA-guided heterochromatinization. In striking contrast, chromatin recognition and excision mechanisms remain mysterious in Metazoans, because the study species are not amenable to functional approaches. Above all, the function of such a mechanism, which has emerged repeatedly throughout evolution, is unknown. Answering these questions will provide significant insights into our understanding of chromatin regulation and genome stability. We fortuitously discovered the phenomenon of PDE in all species of the free-living nematode genus Mesorhabditis. Mesorhabditis, which belong to the same family as C. elegans, have a small ~150 Mb genome and offer many experimental advantages to start elucidating the elimination mechanisms in Metazoans. In this first study, we have used a combination of cytological observation and genomic approaches to describe PDE in Mesorhabditis. We found that the dynamics of chromosome fragmentation and loss are very similar to those described in Ascaris. Elimination occurs once in development, at the third embryonic cell division in all 5 presomatic blastomeres. Similar to other species, Mesorhabditis eliminate repeated elements but also about a hundred unique sequences. Most of the eliminated unique sequences are either pseudogenes or poorly conserved protein-coding genes. Our results raise the possibility that PDE has not been selected for a gene regulatory function in Mesorhabditis but rather mainly is a mechanism to irreversibly silence repeated elements in the soma.
In asexual animals, female meiosis is modified to produce diploid oocytes. Associated with recombination, this is expected to lead to a rapid loss of heterozygosity, with adverse effects on fitness. Many asexuals, however, have a heterozygous genome, the underlying mechanisms being most often unknown. Cytological and population genomic analyses in the nematode Mesorhabditis belari revealed another case of recombining asexual being highly heterozygous genome-wide. We demonstrated that heterozygosity is maintained because the recombinant chromatids of each chromosome pair co-segregate during the unique meiotic division. A theoretical model confirmed that this segregation bias is necessary to account for the observed pattern and likely to evolve under a wide range of conditions. Our study uncovers a new type of cell division involving Directed Chromatid Assortment.
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