A cytosolic invertase is required for normal growth and cell development in the model legume, Lotus japonicus

Neutral/alkaline invertases are a subgroup, confined to plants and cyanobacteria, of a diverse family of enzymes. A family of seven closely-related genes, LjINV1–LjINV7, is described here and their expression in the model legume, Lotus japonicus, is examined. LjINV1 previously identified as encoding a nodule-enhanced isoform is the predominant isoform present in all parts of the plant. Mutants for two isoforms, LjINV1 and LjINV2, were isolated using TILLING. A premature stop codon allele of LjINV2 had no effect on enzyme activity nor did it show a visible phenotype. For LjINV1, premature stop codon and missense mutations were obtained and the phenotype of the mutants examined. Recovery of homozygous mutants was problematic, but their phenotype showed a severe reduction in growth of the root and the shoot, a change in cellular development, and impaired flowering. The cellular organization of both roots and leaves was altered; leaves were smaller and thicker with extra layers of cells and roots showed an extended and broader zone of cell division. Moreover, anthers contained no pollen. Both heterozygotes and homozygous mutants showed decreased amounts of enzyme activity in nodules and shoot tips. Shoot tips also contained up to a 9-fold increased level of sucrose. However, mutants were capable of forming functional root nodules. LjINV1 is therefore crucial to whole plant development, but is clearly not essential for nodule formation or function

Das Verständnis grammatischer Strukturen beim Lesen in Deutsch als Fremdsprache : Ergebnisse einer empirischen Untersuchung

This paper presents an overview of the results from the research project “The psycholinguistics of a grammar for reading German” which has been carried out at the University of Fribourg/Freiburg (CH). The project is based on the idea that the most natural and direct way to multilingualism starts with receptive competence in a third language. In the context of research into European intercomprehension, it investigates Italian and French students' grammatical problems while reading in German as an L3 or L4. To achieve this aim, we worked with especially developed experimental designs. The main research instrument was a reading test which consisted of encyclopaedia articles on imaginary animals. By way of these articles seven grammatical structures of German were tested for their receptive difficulty, with a particular focus on grammatical structures that are traditionally deemed to be ‘difficult’ for learners of German as a second/foreign language. This general opinion, however, is based on teachers’ experience and/or production evidence and not on a systematic investigation of comprehension processes. Further research instruments were a German placement test as well as a self-evaluation of the students' competences of reading in other foreign languages. In addition to that, oral translation exercises into the L1 of the participants were carried out which helped to gain further insight into the process of reading comprehension. In our paper, we will discuss under what circumstances certain grammatical structures pose problems to readers at various levels of language proficiency. On the basis of oral translation protocols, of general cognitive (language) processing mechanisms, and the structure of the German language, tentative explanations will be given as to why certain sentences/structures are more difficult to understand than others and why some structures do not seem to be a problem at all. The results of the study allow fine-grained insights into the impediments (or their absence) particular structures represent for in-depth comprehension of German texts at various levels of competence

Reerensi biologi lengkap : sel & metabolisme

127 hal : ilus ; berwarna ; 30 c

Referensi Biologi lengkap : genetika dan sistem imunitas

120 hal : ilus ; 30 c

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase[C][W]

In all plant species studied to date, sucrose synthase occurs as multiple isoforms. The specific functions of the different isoforms are for the most part not clear. Six isoforms of sucrose synthase have been identified in the model legume Lotus japonicus, the same number as in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). The genes encoding these isoforms are differentially expressed in all plant organs examined, although one, LjSUS4, is only expressed in flowers. LjSUS1 is the most highly expressed in all plant organs tested, except root nodules, where LjSUS3 accounts for more than 60% of the total SUS transcripts. One gene, LjSUS2, produces two transcripts due to alternative splicing, a feature not observed in other species to date. We have isolated plants carrying ethyl methanesulfonate-induced mutations in several SUS genes by targeting-induced local lesions in genomes reverse genetics and examined the effect of null alleles of two genes, LjSUS1 and LjSUS3, on nodule function. No differences were observed between the mutants and wild-type plants under glasshouse conditions, but there was evidence for a nitrogen-starvation phenotype in the sus3-1 mutant and severe impairment of growth in the sus1-1/sus3-1 double mutant under specific environmental conditions. Nodules of sus3-1 mutant plants retained a capacity for nitrogen fixation under all conditions. Thus, nitrogen fixation can occur in L. japonicus nodules even in the absence of LjSUS3 (the major nodule-induced isoform of SUS), so LjSUS1 must also contribute to the maintenance of nitrogen assimilation

Forschungsbericht der Abteilung Soziologie des Instituts fuer Politische Oekonomie der Humboldt-Universitaet Berlin ueber die Untersuchung des Verhaeltnisses von operativer und perspektivischer Taetigkeit im Leitungsprozess

SIGLEISDA, Berlin / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

In der Mitte Berlins

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