Der Einfluss des metakognitiven Wissens auf die Entwicklung der Mathematikleistung am Beginn der Sekundarstufe I

Metakognitives Wissen, also das Wissen über kognitive Prozesse und ihre Steuerung, ist in der Gedächtnis- und Leseverstehensforschung in einem breiten Altersbereich vom Kindergartenalter bis zum Ende der Sekundarstufe I als wichtiger Prädiktor kognitiver Leistungen etabliert. Im Inhaltsbereich Mathematik deuten punktuelle Befunde zu korrelativen Zusammenhängen sowie die Wirknachweise metakognitiver Trainingsprogramme auf leistungsrelevante Effekte des metakognitiven Wissens hin. Jedoch fehlt nach wie vor systematische Forschung zum Zusammenhang zwischen metakognitivem Wissen über Planung, Überwachung und Regulation mathematischer Lösungsprozesse und der Entwicklung in curricularen mathematischen Kompetenzen. Diese Fragestellung wurde anhand von drei Forschungsfragen in der Sekundarstufe I untersucht: (a) Unterscheiden sich die Schüler der drei Schularten zu Beginn der fünften Jahrgangsstufe im metakognitiven Wissen? (b) Kann das metakognitive Wissen die Mathematikleistung zu einem späteren Zeitpunkt vorhersagen? (c) Trägt das metakognitive Wissen einen eigenen Anteil zur Vorhersage der Mathematikleistung bei, der über den Einfluss anderer allgemeiner und mathematikspezifischer Leistungsdeterminanten hinaus geht? Die Analysen basieren auf der längsschnittlichen Untersuchung einer Stichprobe von 763 nordbayerischen Schülerinnen und Schülern aus Gymnasien, Realschulen und Hauptschulen. Neben der Mathematikleistung am Beginn und am Ende der fünften Jahrgangsstufe und dem metakognitiven Wissen wurden als Prädiktoren mathematischer Leistungen allgemeine (Intelligenz und soziale Herkunft) sowie mathematikspezifische Schülermerkmale (Rechenfertigkeiten, mathematisches Selbstkonzept und mathematisches Interesse) erhoben. Die Auswertungen erbrachten bedeutsame Schulartunterschiede im metakognitiven Wissen. Das metakognitive Wissen leistet darüber hinaus auch unter Kontrolle der Vorwissensunterschiede und weiterer allgemeiner und spezifischer Leistungsdeterminanten einen bedeutsamen Beitrag in der Vorhersage der Mathematikleistung am Ende der fünften Jahrgangsstufe. Diese Befunde werden als Nachweis für die substanzielle Bedeutung des metakognitiven Wissens für Ausprägung und Entwicklung mathematischer Kompetenzen am Beginn der Sekundarstufe I interpretiert.Metacognitive knowledge, that is the knowledge about cognitive processes and their regulation is established in memory and reading comprehension research as an important predictor of cognitive achievement. ln mathematics some correlational findings and the effects of metacognitive trainings point to the predictive account of metacognitive knowledge in the prediction of achievement. However, there is no systematic research on the relations between metacognitive knowledge on planning, monitoring and regulation processes in the solution of mathematical problems and the development of curricular mathematical achievement. To explore the relation between metacognitive knowledge and achievement in secondary school three research questions were examined: (a) Are there differences in metacognitive knowledge between the students allocated to the three tracks of German educational system? (b) Does metacognitive knowledge predict mathematics achievement? (c) Does metacognitive knowledge show a unique predictive influence even when other general and specific predictors of mathematics achievement are controlled? Two measurement points at the beginning and at the end of Grade 5 were analyzed. The sample consisted of N=763 students from northern Bavaria on three tracks (academic track, intermediate track and vocational track). Mathematics achievement was assessed at both measurement points. Metacognitive knowledge as well as general (intelligence, socio-economic status) and specific (computation skills, mathematical self-concept and mathematical interest) predictors of achievement were assessed at the first measurement point. Students attending the three tracks differed in metacognitive knowledge. Additionally, metacognitive knowledge predicted mathematics achievement at T2. This predictive influence remained significant even under control for prior knowledge as well as general and the specific determinants of mathematics achievement. The findings show the substantial importance of metacognitive knowledge on mathematics achievement and on development of mathematics achievement at the beginning of secondary school

Homogeneity and persistence of transgene expression by omitting antibiotic selection in cell line isolation

Nonuniform, mosaic expression patterns of transgenes are often linked to transcriptional silencing, triggered by epigenetic modifications of the exogenous DNA. Such phenotypes are common phenomena in genetically engineered cells and organisms. They are widely attributed to features of transgenic transcription units distinct from endogenous genes, rendering them particularly susceptible to epigenetic downregulation. Contrary to this assumption we show that the method used for the isolation of stably transfected cells has the most profound impact on transgene expression patterns. Standard antibiotic selection was directly compared to cell sorting for the establishment of stable cells. Only the latter procedure could warrant a high degree of uniformity and stability in gene expression. Marker genes useful for the essential cell sorting step encode mostly fluorescent proteins. However, by combining this approach with site-specific recombination, it can be applied to isolate stable cell lines with the desired expression characteristics for any gene of interest

Read-through Activation of Transcription in a Cellular Genomic Context

Read-through transcription from the adjacent E1a gene region is required for wild-type (wt) activity of the downstream adenovirus E1b promoter early after infection (read-through activation). However, whether a cellular chromosomal template can support read-through activation is not known. To address this issue, read-through activation was evaluated in the context of stably expressed templates in transfected cells. Inhibition of read-through transcription by insertion of a transcription termination sequence between the E1a and E1b promoters reduced downstream gene expression from stably integrated templates. The results indicate that the mechanism of read-through activation does not depend on the structure of early adenovirus nucleoprotein complexes, a structure that is likely to be different from that of cellular chromatin. Accordingly, this regulatory interaction could participate in the coordinated control of the expression of closely linked cellular genes

Switchgrass (Panicum virgatum L.) polyubiquitin gene (PvUbi1 and PvUbi2) promoters for use in plant transformation

<p>Abstract</p> <p>Background</p> <p>The ubiquitin protein is present in all eukaryotic cells and promoters from ubiquitin genes are good candidates to regulate the constitutive expression of transgenes in plants. Therefore, two switchgrass (<it>Panicum virgatum </it>L.) ubiquitin genes (<it>PvUbi1 </it>and <it>PvUbi2</it>) were cloned and characterized. Reporter constructs were produced containing the isolated 5' upstream regulatory regions of the coding sequences (i.e. <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters) fused to the <it>uidA </it>coding region (<it>GUS</it>) and tested for transient and stable expression in a variety of plant species and tissues.</p> <p>Results</p> <p><it>PvUbi1 </it>consists of 607 bp containing <it>cis</it>-acting regulatory elements, a 5' untranslated region (UTR) containing a 93 bp non-coding exon and a 1291 bp intron, and a 918 bp open reading frame (ORF) that encodes four tandem, head -to-tail ubiquitin monomer repeats followed by a 191 bp 3' UTR. <it>PvUbi2 </it>consists of 692 bp containing <it>cis</it>-acting regulatory elements, a 5' UTR containing a 97 bp non-coding exon and a 1072 bp intron, a 1146 bp ORF that encodes five tandem ubiquitin monomer repeats and a 183 bp 3' UTR. <it>PvUbi1 </it>and <it>PvUbi2 </it>were expressed in all examined switchgrass tissues as measured by qRT-PCR. Using biolistic bombardment, <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters showed strong expression in switchgrass and rice callus, equaling or surpassing the expression levels of the CaMV <it>35S, 2x35S, ZmUbi1</it>, and <it>OsAct1 </it>promoters. GUS staining following stable transformation in rice demonstrated that the <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters drove expression in all examined tissues. When stably transformed into tobacco (<it>Nicotiana tabacum</it>), the <it>PvUbi2+3 </it>and <it>PvUbi2+9 </it>promoter fusion variants showed expression in vascular and reproductive tissues.</p> <p>Conclusions</p> <p>The <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters drive expression in switchgrass, rice and tobacco and are strong constitutive promoter candidates that will be useful in genetic transformation of monocots and dicots.</p