The Role of General and Subject-specific Language Skills when Learning Mathematics in Elementary School

The role of skills in the language of instruction for mathematics learning is well established by longitudinal studies at the primary school level. Explanations for these relations lead to the question: are they mostly due to general, domain-overarching language skills, or does the command of subject-specific language registers play an important role? Integrating prior research threads, we propose two instruments to measure subject-specific language skills in mathematics: One measuring mathematical vocabulary, and one measuring mathematical text comprehension. We report on a longitudinal study with N = 237 German grade 3 students, which investigated the predictive value of these instruments beyond prior arithmetic skills, general language skills, and control variables such as general cognitive skills and socio-economic status on students’ later arithmetic skills. We applied a multidimensional assessment model to measure arithmetic skills. Apart from replicating the prominent role of general language skills found in earlier studies, our results indicate a substantial, additional role of subject-specific language skills for the development of mathematics skills. These relations could be identified for knowledge of mathematical vocabulary, as well as for mathematical text comprehension. The results indicate that fostering subject-specific language skills already at the primary school level is not only one of many goals of mathematics instruction, but is a core prerequisite to supporting mathematical skill acquisition

A novel allele of FILAMENTOUS FLOWER reveals new insights on the link between inflorescence and floral meristem organization and flower morphogenesis

<p>Abstract</p> <p>Background</p> <p>The <it>Arabidopsis </it><it>FILAMENTOUS FLOWER (FIL) </it>gene encodes a YABBY (YAB) family putative transcription factor that has been implicated in specifying abaxial cell identities and thus regulating organ polarity of lateral organs. In contrast to double mutants of <it>fil </it>and other <it>YAB </it>genes, <it>fil </it>single mutants display mainly floral and inflorescence morphological defects that do not reflect merely a loss of abaxial identity. Recently, <it>FIL </it>and other <it>YABs </it>have been shown to regulate meristem organization in a non-cell-autonomous manner. In a screen for new mutations affecting floral organ morphology and development, we have identified a novel allele of FIL, <it>fil-9 </it>and characterized its floral and meristem phenotypes.</p> <p>Results</p> <p>The <it>fil-9 </it>mutation results in highly variable disruptions in floral organ numbers and size, partial homeotic transformations, and in defective inflorescence organization. Examination of meristems indicates that both <it>fil-9 </it>inflorescence and floral meristems are enlarged as a result of an increase in cell number, and deformed. Furthermore, primordia emergence from these meristems is disrupted such that several primordia arise simultaneously instead of sequentially. Many of the organs produced by the inflorescence meristems are filamentous, yet they are not considered by the plant as flowers. The severity of both floral organs and meristem phenotypes is increased acropetally and in higher growth temperature.</p> <p>Conclusions</p> <p>Detailed analysis following the development of <it>fil-9 </it>inflorescence and flowers throughout flower development enabled the drawing of a causal link between multiple traits of <it>fil-9 </it>phenotypes. The study reinforces the suggested role of <it>FIL </it>in meristem organization. The loss of spatial and temporal organization of <it>fil-9 </it>inflorescence and floral meristems presumably leads to disrupted cell allocation to developing floral organs and to a blurring of organ whorl boundaries. This disruption is reflected in morphological and organ identity aberrations of <it>fil-9 </it>floral organs and in the production of filamentous organs that are not perceived as flowers. Here, we show the role of <it>FIL </it>in reproductive meristem development and emphasize the potential of using <it>fil </it>mutants to study mersitem organization and the related effects on flower morphogenesis.</p

Voltage affects the dissociation rate constant of the m2 muscarinic receptor.

G-protein coupled receptors (GPCRs) comprise the largest protein family and mediate the vast majority of signal transduction processes in the body. Until recently GPCRs were not considered to be voltage dependent. Newly it was shown for several GPCRs that the first step in GPCR activation, the binding of agonist to the receptor, is voltage sensitive: Voltage shifts the receptor between two states that differ in their binding affinity. Here we show that this shift involves the rate constant of dissociation. We used the m2 muscarinic receptor (m2R) a prototypical GPCR and measured directly the dissociation of [(3)H]ACh from m2R expressed Xenopus oocytes. We show, for the first time, that the voltage dependent change in affinity is implemented by voltage shifting the receptor between two states that differ in their rate constant of dissociation. Furthermore, we provide evidence that suggest that the above shift is achieved by voltage regulating the coupling of the GPCR to its G protein

Turning off <em>Bacillus cereus</em> quorum sensing system with peptidic analogs

International audienceWe explored quenching of the PlcR-PapR quorum-sensing system in Bacillus cereus. We generated PapR(7)-peptidic derivatives that inhibit this system and thus the production of virulence factors, reflected by a loss in hemolytic activity, without affecting bacterial growth. To our knowledge, these peptides represent the first potent synthetic inhibitors of quorum-sensing in B. cereus