High velocity dispersion in a rare grand-design spiral galaxy at redshift z = 2.18

Although grand-design spiral galaxies are relatively common in the local Universe, only one has been spectroscopically confirmed to lie at redshift z?>?2 (HDFX 28; z = 2.011); and it may prove to be a major merger that simply resembles a spiral in projection. The rarity of spirals has been explained as a result of disks being dynamically 'hot' at z?>?2 (refs 2-5), which may instead favour the formation of commonly observed clumpy structures. Alternatively, current instrumentation may simply not be sensitive enough to detect spiral structures comparable to those in the modern Universe. At z?相似文献   

Induction of micronuclei in PHA-stimulated human lymphocyte cultures by therapeutic radiation

Summary Micronuclei frequency and percent of chromosome breaks increases significantly in adults whose thymus glands were irradiated in infancy and after irradiation of cancer patients.Acknowledgments. This work was supported by a grant, No. CA-14876, from the National Cancer Institute. Rita Giuliano gave valuable technical assistance.     

Inhibition of arginase in sheep brain homogenates by some L-amino acids

Summary The effect of 16 L-amino acids on the activity levels of arginase in sheep brain homogenates was studied. The amino acids leucine, valine, lysine, and ornithine inhibited arginase activity significantly. The other amino acids tested did not show a significant influence on arginase activity. The inhibition was related to the carbon chain length of the amino acids.     

Effect of water temperature on the predatory efficiency ofGambusia affinis

Zusammenfassung Fütterungsversuche anGambusia affinis zeigten, dass die Anzahl der Mückenlarven, die von den Fischen gefressen werden, bei erhöhter Wassertemperatur zunimmt. Es scheint, dass diese Reaktion weitgehend von Geschlecht und physiologischem Zustand abhängig ist.     

Cytochemical studies on histone moiety of an asynaptic mutant ofPhaseolus mungo

Zusammenfassung Die Wurzelspitzen und meiotischen Prophasezellen normaler und asynaptischer Pflanzen vonPhaseolus mungo wurden nach Azetylierung oder Desaminierung der Histone mit alkalischem Fastgreen, Bromphenolblau und Eosin Y gefärbt. Die asynaptischen Mutanten ergaben einen erhöhten Wert an labilen lysinreichen Kernhistonen.     

Control of CFTR chloride conductance by ATP levels through non-hydrolytic binding.

Site-specific mutation and membrane reconstitution experiments provide compelling evidence that the product of the gene which is at fault in the disease cystic fibrosis, termed the cystic fibrosis transmembrane conductance regulator (CFTR), is a small-conductance chloride channel activated by phosphorylation. As transport of chloride ions is passive, the predicted presence of two nucleotide-binding domains in CFTR seems as puzzling as a report that ATP hydrolysis is essential to activate the channel. We now find that in the sweat duct, which expresses high levels of CFTR and has a very high Cl- conductance, intracellular concentrations of ATP must be about normal (5 mM) for activation of this conductance, apparently by a non-hydrolytic, perhaps allosteric, mechanism. This passive dependence on ATP should mean that even a modest depletion of cell energy levels will significantly lower the energy demands of electrolyte transport by decreasing chloride conductance. We believe this direct coupling between cellular ATP levels and chloride channel activity is an adaptive mechanism to protect the tissue from damage resulting from excessive energy depletion.