ELECTROPHORESIS OF STEROLS : II. ERGOSTEROL

The electrophoretic behavior of powdered ergosterol crystals is identical with that previously found for cholesterol within the limits of experimental error. Evidence for an adsorption hypothesis is presented to explain this phenomenon.     

THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE

Abstract— The distribution of [¹⁴C]-labeIled material into subcellular fractions of 15-day-old rat brain was studied as a function of time after intracerebral injection of [2-¹⁴C]mevalonic acid. As previously shown for adult brain, the data indicated the microsomal fraction to be the site of sterol biosynthesis. The synaptosomal fraction exhibited a marked early uptake of [¹⁴C]-nonsaponifiable material. Total radioactivity in both myelin and myelin-like fractions remained low in comparison to that in the other subcellular fractions at all time periods examined. At 2 h after injection, labelled digitonin-precipitable material was demonstrable in all subcellular fractions. Examination of the [¹⁴C]-labelled nonsaponifiable material by thin-layer chromatography indicated the rapid appearance of labelled 4-desmethyl sterol in all subcellular fractions, with the most rapid appearance in the myelin fraction, followed in decreasing order by microsomal, synaptosomal, and mitochondrial fractions. Examination of [¹⁴C] digitonin-precipitable material from each fraction by the dibromide method demonstrated that although 4-desmethyl sterol appeared quickly, the formation of cholesterol was slow in all fractions, an effect that had been reported earlier for adult brain.     

THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE

Abstract— The distribution of ¹⁴C into several subcellular fractions of adult rat brain was studied as a function of time, following intracerebral injection of [2-¹⁴C]mevalonic acid. As expected from previous studies, the microsomal fraction was indicated as the site of sterol biosynthesis. The myelin fraction showed a marked and early uptake of ^I4C-labelled, digitonin-precipitable material. This was assumed to be a non-enzymic uptake of sterol intermediates. The mitochondrial fraction exhibited a rapid uptake of ¹⁴C-labelled, nonsaponifiable material, but a very slow accumulation of ¹⁴C-labelled, digitonin-precipitable product. Examination of the nonsaponifiable ¹⁴C-fractions by TLC showed a rapid appearance of labelled 4-desmethyl sterols in the microsomal fraction. The myelin fraction selectively retained 4,4'-dimethyl sterol but seemed to release this with time, possibly to be further metabolized by the microsomes. Examination of [¹⁴C]digitonin-precipitable material by the dibromide method showed that although labelled 4-desmethyl sterol appeared quite early, cholesterol itself was formed slowly in all fractions.     

FURTHER INVESTIGATIONS ON PHYTOCHROME-CONTROLLED SUCROSE UPTAKE INTO APICAL BUDS OF ETIOLATED PEAS

When etiolated pea epicotyls are severed at the ground level and immersed basally into ¹⁴C-sucrose, P_fr phytochrome promotes both the uptake of label into the terminal bud and the growth of that bud. Movement of label up the epicotyl requires active metabolism; it is inhibited by anaerobiosis, low temperature, and 2,4-dinitrophenol. Increase in bud label is detectable within 15–30 min and precedes the first detectable increase in growth rate. Stem tissues, whose growth is inhibited by red light, show a corresponding decrease in content of label. Sixty to 70% of the label of the bud is carbohydrate; the remainder is found in organic acids and phosphates, amino acids, and cell wall components. The major metabolic effects of red irradiation are (1) promotion of sucrose hydrolysis, probably through an induction of higher β-fructofuranosidase activity, and (2) enhanced incorporation of sucrose into ethanolinsoluble wall components.     

DISSIMILARITY OF INNER AND OUTER PROTOPLASMIC SURFACES IN VALONIA. III

Evidence that the inner and outer protoplasmic surfaces in Valonia are unlike is found in the high P.D. across the protoplasm when the external solution has the same composition as the vacuolar sap. Earlier experiments with artificial sap have been repeated, using natural as well as artificial sap. Good agreement between the data with the natural and the artificial solution was found both in the magnitude of the P.D.''s observed and in the shape of the P.D.-time curves. The P.D.''s, however, were considerably higher than the values formerly reported as usual, while the cells proved much less liable to alteration produced by exposure to sap. It is suggested that the cells used in the recent experiments were in a more vigorous condition, perhaps as a result of exposure to stronger illumination. The interpretation of the shape of the P.D.-time curves, proposed in an earlier report, and based on the theory of protoplasmic layers, is further discussed. It is assumed that the fluctuations in P.D. are due to an increase in the concentration of K in the main body of the protoplasm.     

SYSTEMATIC OCCURRENCE OF STEROLS IN LATEX OF ARACEAE: SUBFAMILY COLOCASIOIDEAE

Latex from representative New and Old World colocasioid species was analyzed by combined gas chromatography-mass spectrometry for the presence of sterols. Free sterols were detected in latex of all New World species examined, and were localized in ca. 1 μm terpenoid particles which are abundant and account for the white-opaque appearance of the latex. The sterol profiles were qualitatively and/or quantitatively distinct for each of the New World species examined. No free sterols were detected in latex of Old World genera examined, which are consistently clear to cloudy, and lack terpenoid particles. The presence of free sterols as small particles is typical of New World Colocasioideae with white latex. The results of this study provide chemical evidence for distinguishing Old and New World groups of Colocasioideae, which was recently proposed based on stem vasculature, pollen, and leaf type. This is the first report of sterol-rich latex in a monocotyledon.     

INVESTIGATIONS ON FUNGICIDES. III. THE FUNGITOXICITY OF 3- AND 5-ALKYL-SALICYLANILIDES AND PARA-CHLOROANILIDES

The anilides and para -chloroanilides have been prepared from the first four homologues of the 3- and 5-alkylsalicylic acid series and the fungistatic activity of these compounds has been assessed by two methods. In tests against mycelium, the chloroanilides usually induced less retardation of growth than the corresponding anilides. The effect of introducing an alkyl grouping was in general to reduce the fungistatic effect but with the n -propyl derivatives this trend was less marked. Salicylanilide gave the greatest over-all inhibition of the fungi investigated.     

INVESTIGATIONS OF NORTH AMERICAN CYCADEOIDS: MONANTHESIA

Delevoryas , Theodore . (Yale U., New Haven, Conn.) Investigations of North American cycadeoids: Monanthesia. Amer. Jour. Bot. 46(9): 657–666. Illus. 1959.—A study of the cycadeoid trunks from the Upper Cretaceous Mesaverde formation of northwestern New Mexico, which are in the collections of the Peabody Museum of Natural History, Yale University, has been completed. These plants had columnar trunks with persistent leaf bases and a cone in the axil of every leaf. The vascular supply of the cone is derived from the fusion of two cortical bundles which arise from two leaf traces, neither of which supplies the subtending leaf. Enough difference appears to exist between these forms and Cycadeoidea to warrant a separate generic designation. Monanthesia is the generic name used, and the single species, M. magnifica, is considered to include all the stems from the New Mexico localities. The pattern of vascularization of cones seems to suggest that they are foliar structures and that Monanthesia is probably a more advanced form than Cycadeoidea.     

INVESTIGATIONS OF NORTH AMERICAN CYCADEOIDS: CONES OF CYCADEOIDEA

Delevoeyas , Theodore . (Yale U., New Haven, Conn.) Investigations of North American cycadeoids: cones of Cycadeoidea . Amer. Jour. Bot. 50(1): 45–52. Illus. 1963.—A reinvestigation of the morphology of cones of Cycadeoidea indicates that they did not expand into flower-like structures at maturity The microsporangiate region was actually a compound synangium fused peripherally and, for at least part of the time, along the inner surface surrounding the ovulate receptacle. Capping the microsporangiate region is a massive parenchymatous dome. Synangia were borne along trabecular structures which connected the outer part of the microsporangiate structure to the inner face. Pollen may have been released after an abscission of the entire compound synangium.     

THE EFFECT OF RENNIN UPON CASEIN : II. FURTHER CONSIDERATION OF THE PROPERTIES OF PARACASEIN.

The properties of the paracasein and casein preparations studied are compared in Table VI. See PDF for Structure I. Casein retains its characteristic solubility in NaOH: (1) after being exposed to a high degree of alkalinity during its preparation, (2) when recovered from partially hydrolyzed solutions in NaOH, and (3) after being kept for a prolonged time at the isoelectric point at 5°C. II. It follows from I, that: (1) paracasein is not identical to casein modified by an excess of alkali, and that (2) this protein was not produced from casein by a partial hydrolysis of the latter in presence of NaOH.     

INVESTIGATIONS OF NORTH AMERICAN CYCADEOIDS: EARLY OVULE ONTOGENY

Ovules on cones of the genus Cycadeoidea from the Cretaceous were found preserved at the pregametophytic stage of nucellar development. At this stage, the ovules are distinct from those of extant gymnosperms in that there is a greater degree of differentiation in both the integuments and the nucellus in Cycadeoidea. Linear clusters of three or four cells, which consistently occur in the middle of the nucellus, are interpreted to be the remains of linear tetrads of megaspores. This example of exceptional preservation allows, for the first time, a comparison of early ontogenetic events in a fossil seed with those of extant seeds.