Induction of thermosensitivity and salt sensitivity in wheat roots (Triticum aestivum) and the effect of kinetin

Zusammenfassung Die Hitzesensibilisierung von Weizenwurzelmeristemen kann durch Kältebehandlung oder Kinetinzugaben zumindest teilweise rÜckgängig gemacht werden.     

The gene disrupted in Marinesco-Sjögren syndrome encodes SIL1, an HSPA5 cochaperone

We identified the gene underlying Marinesco-Sj?gren syndrome, which is characterized by cerebellar ataxia, progressive myopathy and cataracts. We identified four disease-associated, predicted loss-of-function mutations in SIL1, which encodes a nucleotide exchange factor for the heat-shock protein 70 (HSP70) chaperone HSPA5. These data, together with the similar spatial and temporal patterns of tissue expression of Sil1 and Hspa5, suggest that disturbed SIL1-HSPA5 interaction and protein folding is the primary pathology in Marinesco-Sj?gren syndrome.     

Crystal structure of a copper-transporting PIB-type ATPase

Heavy-metal homeostasis and detoxification is crucial for cell viability. P-type ATPases of the class IB (PIB) are essential in these processes, actively extruding heavy metals from the cytoplasm of cells. Here we present the structure of a PIB-ATPase, a Legionella pneumophila CopA Cu(+)-ATPase, in a copper-free form, as determined by X-ray crystallography at 3.2 ? resolution. The structure indicates a three-stage copper transport pathway involving several conserved residues. A PIB-specific transmembrane helix kinks at a double-glycine motif displaying an amphipathic helix that lines a putative copper entry point at the intracellular interface. Comparisons to Ca(2+)-ATPase suggest an ATPase-coupled copper release mechanism from the binding sites in the membrane via an extracellular exit site. The structure also provides a framework to analyse missense mutations in the human ATP7A and ATP7B proteins associated with Menkes' and Wilson's diseases.     

Phytate: impact on environment and human nutrition. A challenge for molecular breeding

Phytic acid （PA） is the primary storage compound of phosphorus in seeds accounting for up to 80% of the total seed phosphorus and contributing as much as 1.5% to the seed dry weight. The negatively charged phosphate in PA strongly binds to metallic cations of Ca, Fe, K, Mg, Mn and Zn making them insoluble and thus unavailable as nutritional factors. Phytate mainly accumulates in protein storage vacuoles as globoids, predominantly located in the aleurone layer （wheat, barley and rice） or in the embryo （maize）. During germination, phytate is hydrolysed by endogenous phytase（s） and other phosphatases to release phosphate, inositol and micronutrients to support the emerging seedling. PA and its derivatives are also implicated in RNA export, DNA repair, signalling, endocytosis and cell vesicular trafficking. Our recent studies on purification of phytate globoids, their mineral composition and dephytinization by wheat phytase will be discussed. Biochemical data for purified and characterized phytases isolated from more than 23 plant species are presented, the dephosphorylation pathways of phytic acid by different classes of phytases are compared, and the application of phytase in food and feed is discussed.     

Spore germination inHebeloma stimulated by living plant roots

Summary Basidiospores from 14 strains ofHebeloma (Agaricales) representing 5 groups of mycorrhiza-forming species were tested for germination on a nutrient agar medium. Germination occurred in 13 strains but never exceeded 0.1%. A 10-fold increase or more in germination percentage was obtained in 4 out of 7 tested spore collections only by placing the growing root of a pine seedling among the spores on the agar medium.This investigation was in part supported by a grant from the Swedish National Science Research Council.The authors wish to thank Dr G. Bruchet for taxonomical identification of the fruit-body material.This work was carried out when D. B. was holding a bilateral French-Swedish exchange fellowship (1978–79) through the Swedish Institute, Stockholm.     

Mutations in DMRT3 affect locomotion in horses and spinal circuit function in mice

Locomotion in mammals relies on a central pattern-generating circuitry of spinal interneurons established during development that coordinates limb movement. These networks produce left-right alternation of limbs as well as coordinated activation of flexor and extensor muscles. Here we show that a premature stop codon in the DMRT3 gene has a major effect on the pattern of locomotion in horses. The mutation is permissive for the ability to perform alternate gaits and has a favourable effect on harness racing performance. Examination of wild-type and Dmrt3-null mice demonstrates that Dmrt3 is expressed in the dI6 subdivision of spinal cord neurons, takes part in neuronal specification within this subdivision, and is critical for the normal development of a coordinated locomotor network controlling limb movements. Our discovery positions Dmrt3 in a pivotal role for configuring the spinal circuits controlling stride in vertebrates. The DMRT3 mutation has had a major effect on the diversification of the domestic horse, as the altered gait characteristics of a number of breeds apparently require this mutation.     

Vitamin requirements of decotylised pea seedlings cultivated in the dark

Zusammenfassung Abgeschnittene Erbsenwurzeln wachsen, wie schon frühere Untersuchungen gezeigt haben, unbegrenzt in einer Nährlösung mit Thiamin (Vitamin B₁) und Niacin als die einzigen zugesetzten Vitamine. Das konnte auch mit der in dieser Arbeit verwendeten Erbsenrasse bestätigt werden. Dekotylisierte Erbsenkeimlinge, die unter denselben Bedingungen in Dunkelheit kultiviert wurden, brauchten aber Thiamin undPyridoxin (Vitamin B₆). Ein Bedürfnis von Niacin zeigte sich dagegen während der angewandten Versuchszeit bei diesen Keimlingen nicht.     

Vitamin requirements ofNemalion multifidum

Zusammenfassung Es ist gelungen,Nemalion multifidum, eine marine Floridee, in axenische Kultur zu bekommen. Die Alge wurde in einer synthetischen Nährlösung gezüchtet. Wenn sie ohne Vitamine 2 Monate kultiviert wurde, konnte ein Zusatz einer Vitaminmischung den Zuwachs verdoppeln. Die wirksamen Vitamine waren am Anfang B₁₂ oder B₆; wenn die Alge aber längere Zeit in Hungerkultur gezüchtet worden war, konnte nur die B₁₂-Analoge, Factor Ib, den Zuwachs erhöhen.