In situ conversion of protochlorophyllide b to protochlorophyllide a in barley. Evidence for a novel role of 7-formyl reductase in the prolamellar body of etioplasts

We recently put forth a model of a protochlorophyllide (Pchlide) light-harvesting complex operative during angiosperm seedling de-etiolation (Reinbothe, C., Lebedev, N., and Reinbothe, S. (1999) Nature 397, 80–84). This model, which was based on in vitro reconstitution experiments with zinc analogs of Pchlide a and Pchlide b and the two NADPH:protochlorophyllide oxidoreductases (PORs), PORA and PORB, of barley, predicted a 5-fold excess of Pchlide b, relative to Pchlide a, in the prolamellar body of etioplasts. Recent work (Scheumann, V., Klement, H., Helfrich, M., Oster, U., Schoch, S., and Rüdiger, W. (1999) FEBS Lett. 445, 445–448), however, contradicted this model and reported that Pchlide b would not be present in etiolated plants. Here we demonstrate that Pchlide b is an abundant pigment in barley etioplasts but is rather metabolically unstable. It is rapidly converted to Pchlide a by virtue of 7-formyl reductase activity, an enzyme that had previously been implicated in the chlorophyll (Chl) b to Chl a reaction cycle. Our findings suggest that etiolated plants make use of 7-formyl reductase to fine tune the levels of Pchlide b and Pchlidea and thereby may regulate the steady-state level of light-harvesting POR-Pchlide comple

The origins of stability of spontaneous vesicles

Equilibrium unilamellar vesicles are stabilized by one of two distinct mechanisms depending on the value of the bending constant. Helfrich undulations ensure that the interbilayer potential is always repulsive when the bending constant, K, is of order kBT. When K ≫ kBT, unilamellar vesicles are stabilized by the spontaneous curvature that picks out a particular vesicle radius; other radii are disfavored energetically. We present measurements of the bilayer elastic constant and the spontaneous curvature, Ro, for three different systems of equilibrium vesicles by an analysis of the vesicle size distribution determined by cryo-transmission electron microscopy and small-angle neutron scattering. For cetyltrimethylammonium bromide (CTAB)/sodium octyl sulfonate catanionic vesicles, K = .7 kBT, suggesting that the unilamellar vesicles are stabilized by Helfrich-undulation repulsions. However, for CTAB and sodium perfluorooctanoate (FC7) vesicles, K = 6 kBT, suggesting stabilization by the energetic costs of deviations from the spontaneous curvature. Adding electrolyte to the sodium perfluorooctanoate/CTAB vesicles leads to vesicles with two bilayers; the attractive interactions between the bilayers can overcome the cost of small deviations from the spontaneous curvature to form two-layer vesicles, but larger deviations to form three and more layer vesicles are prohibited. Vesicles with a discrete numbers of bilayers at equilibrium are possible only for bilayers with a large bending modulus coupled with a spontaneous curvature.

A study of the possible relationship between radioactivity and toxicity in fishes from the central Pacific /

"May 1960 {TIS Issuance Date]"

Joh. Helfrici Jungken ... Manuale, sive Vade mecum praxeos medicae modernae pro memoria sublevanda conscriptum

Contiene según consta en port. : "Ubi prior pars continet utriusque sexus corporis humani morbos internos in genere ; pars altera gravidarum sive praegnantium, nec non puerperarum atque infantum morbos in specie pertractat ; tertia vero morbos chirurgicae medicinae parti, partim relictos, ut priores in compendio"

Corpus pharmaceutico-chymico-medicum sive Concordantia pharmaceuticorum compositorum discordans, modernis medicinae practicis dicata ... /

Mode of access: Internet.

Tractatus politico-juridicus de ligno et lapide : quo praecipuam juris forestalis partem, materiam arborum plantationis, conservationis, dominii, ejusque effectuum tum in perceptione glandium quum ipsorum lignorum ...; cum adiecto in majorem intelligentiam quaestionum miscellanearum fasciculo /

Mode of access: Internet.

Lexicon chimico-pharmaceuticum in duas partes divisum : quorum prior continet selectos processus selectus chimicos, sive medicamentorum chimicorum vulgò, sed usualium potissimum elaborationes : ex recentiorum curiosorum medicorum laboratoriis noviter prodeuntes, selectas & probatas : altera pars composita pharmaceutica tam usualia, quam alia his subordinata & & ratione consentanea exhibet /

Mode of access: Internet.

Joh. Helffrici Jungken ... Chymia experimentalis, sive, Naturalis philosophia mechanica : ubi prior pars generosiorum remediorum fabricam ex triplici regno cum omnibus manipulationibus, fideliter exhibet. Pars alter eadem medicamenta, inter alia, ad quoscunque morbos generaliter adaptare docet. Adjectis monitis medicis affectibus puerorum concernentibus. Nec non experimentis rerum naturalium principa commentarii, loco illustrantibus.

Mode of access: Internet.

Double insulated droll tests.

Prepared by William J. Helfrich and Richard L. Reynolds.

An assessment of regional ground-water contamination in Illinois /

"HWRIC RR 023."

Encyclopedia iuris vniversi, opus theorico practicum, docentibus aeque, ac discentibus in aulis, ac foro versantibus, apprime vtile, multorunque grauissimorum virorum votis expetitum et necessarium : quique constans partibus ... /

Mode of access: Internet.