Purification and properties of sterol: UDPG glucosyltransferase in cell culture of Digitalis purpurea

Sterol: UDPG glucosyltransferase was isolated for the first time from cell culture. Digitalis purpurea cultured cells had 2–5 times higher activity than that of the original plant. The enzyme in the particulate fraction was purified 70.2-fold from cell culture and 76-fold from the plant by cellular fractionation and column chromatography. The properties of purified enzyme from cultured cells were similar to those of the enzyme from the intact plant. The substrate specificity was the highest for a phytosterol.     

Action spectrum of phototaxis in a cryptomonad alga, Cryptomonas sp.

The action spectrum of the positive topo-phototaxis in Cryptomonaswas determined by photometry in the region of 400 to 680 nmat a stimulus intensity of 8.3 ? 10^–11 Einsteins cm^–2sec^–1. The action spectrum had a main peak at about 560nm unlike peaks for most other flagellated algae. Blue lightwas not very effective and red light above 640 nm had not effect. Swimming rates of individual organisms were measured by darkfield photomicrography. We concluded that the photokinetic effectwas negligible. Among the component pigments of this alga, phycoerythrin hadan absorption spectrum whose main peak appeared to coincidewith that of the phototactic action spectrum. (Received October 31, 1973; )     

Isolation of a naturally occurring inhibitor for dark Pfr reversion from etiolated Pisum epicotyls

The in vitro reversion of Pfr to Pr in the dark was preventedby adding the low molecular weight fraction obtained from aSephadex G-50 column chromatogram to the crude homogenate ofetiolated pea epicotyl tissues, and by the methanolic and boilingaquous extracts of the tissue. The degree of inhibition of darkPfr reversion was related to the logarithmic concentrationsof the methanol-extractable material. The active substance washighly soluble in water-saturated n-butanol; but not in chloroform,ethyl acetate, n-hexane, benzene and pure n-butanol. Thus, alow molecular substance(s) which can inhibit dark Pfr reversionwas indicated to be contained in pea epicotyl tissues. (Received January 28, 1975; )