Probing nonequivalent sites in iron phosphide Fe2P and its mechanism of phase transition

Comparative studies of two polymorphs (P (6) over bar 2m and Pnma structures) of Fe2P up to 16.8 GPa and 1800 +/- 200 K were performed using Mossbauer spectroscopy combined with diamond anvil cell and laser heating facilities. Mossbauer spectra were collected before and after its phase transition from P (6) over bar 2m to Pnma structures. Mossbauer hyperfine parameters in two non-equivalent sites Fe I and Fe II in Fe2P were evaluated and compared. An evident drop of quadrupole splitting for the Fe-57 in Fe II site was observed in its high temperature polymorph, indicating that a more sensitive pyramidal Fe II site to pressure change could serve as a trigger to this phase transition.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322175100015&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, Condensed MatterSCI(E)0ARTICLE7null8

β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast

Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast β-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function