Two Additional Phosphorylases in Developing Maize Seeds

Two additional phosphorylases (III and IV) have been detected in developing seeds of maize. Phosphorylase IV is found only in the embryo (with scutellum). It is also present in the embryo of the germinating seed where its activity is 90-fold greater than the activity in the developing embryo 22 days after pollination. Phosphorylase IV is eluted from a DEAE-cellulose column in the same fraction as phosphorylase I of the endosperm, and the 2 enzymes are similar in many respects. Phosphorylase IV is distinguished from phosphorylase I by electrophoretic mobility, by pH optimum, and because its properties are not affected by the shrunken-4 mutation.Phosphorylase III is found both in the endosperms and embryos of developing seeds. Activity for this enzyme is not detected in crude homogenates nor eluates from a DEAE-cellulose column apparently because it complexes with a non-dialyzable, heat-labile inhibitor. High activity is found after protamine sulfate fractionation. Phosphorylase III is bound to protamine sulfate and is then removed by washing with 0.3 m phosphate buffer. Phosphorylase III activity in the endosperm is not detectable 8 days after pollination but is present 12 days after pollination. Phosphorylase III differs from phosphorylases I, II, and IV in several respects-pH optimum, pH-independent ATP inhibition, time of appearance in the endosperm, and because purine and pyrimidine nucleotides are equally inhibitory. In common with phosphorylase II, phosphorylase III apparently does not require a primer to initiate the synthesis of an amylose-like polymer.     

Ultrastructural localization of zinc in rat exocrine pancreas by autoradiography

Summary ⁶⁵Zn was infused at a constant rate for 10 days into a rat. Glutaraldehyde fixed, Epon-araldite embedded ultrathin sections of pancreatic tissue were coated with Ilford L4 emulsion and at 211 days exposure were developed. Silver grains were found over the zymogen granules and over the rough endoplasmic reticulum of exocrine cells. Islet tissue was not observed in these studies. The failure of other zinc localization methods to demonstrate zinc in acinar tissue is discussed as are some of the pitfalls of the autoradiographic method and suggestions for future improvement.Published with the approval of the Director of the Wisconsin Agricultural Experiment Station, Madison. Supported in part by USPHS Research Grant AM-05606 from the Nat. Institute of Arthritis and Metabolic Diseases.Supported by an NIH post-doctoral fellowship.     

Biosynthesis of the Fungal Estrogen F-2 and a Naturally Occuring Derivative (F-3) by Fusarium moniliforme

The fungal metabolites, F-2 and F-3, associated with estrogenism in swine, are produced by some races of Fusarium moniliforme isolated from toxic feeds.     

Biochemical studies of bacterial sporulation and germination. XII. A sulfonic acid as a major sulfur compound of Bacillus subtilis spores

A sulfonic acid found to be a major constituent of spores of Bacillus subtilis was provisionally identified as 3-l-sulfolactic acid. This compound was completely absent from vegetative cells during growth, but large amounts accumulated in sporulating cells just before the development of refractile spores. Essentially all of the accumulated sulfolactic acid was eventually incorporated into the nature spore, where it may represent more than 5% of the dry weight of the spore. Germination resulted in the rapid and complete release into the medium of unaltered sulfolactic acid. This compound was not found in spores of Bacillus megaterium, B. cereus, or B. thuringiensis.     

Electron microscopy of spore germination and cell wall formation in Mucor rouxii

Summary The fine structure of ungerminated and aerobically germinated sporangiospores of Mucor rouxii was compared. The germination process may be divided into two stages: I, spherical growth; II, emergence of a germ tube. In both stages, germination is growth in its strictest sense with overall increases in cell organelles; e.g., the increase in mitochondria is commensurate with the overall increase in protoplasmic mass. Noticeable changes occurring during germination are the disappearance of electron-dense lipoid bodies, formation of a large central vacuole and, most strikingly, formation of a new cell wall. Unlike many other fungi, M. rouxii does not germinate by converting the spore wall into a vegetative wall. Instead, as in other Mucorales, a vegetative wall is formed de novo under the spore wall during germination stage I. This new wall grows out, rupturing the spore wall, to become the germ tube wall. Associated with the apical wall of the germ tube is an apical corpuscle previously described. The vegetative wall exhibits a nonlayered, uniformly microfibrillar appearance in marked distinction to the spore wall which is triple-layered, with two thin electron dense outer layers, and a thick transparent inner stratum. The lack of continuity between the spore and vegetative walls is correlated with marked differences in wall chemistry previously reported. A separate new wall is also formed under the spore wall during anaerobic germination leading to yeast cell formation. On the other hand, in the development of one vegetative cell from another, such as in the formation of hyphae from yeast cells, the cell wall is structurally continuous. This continuity is correlated with a similarity in chemical composition of the cell wall reported earlier.     

Control of glycogen levels in brain

Abstract— Prolonged (6 hr) anaesthesia with phenobarbital in mice or rats results in a doubling or tripling of brain glycogen. Increases were also observed if high levels of plasma glucose were maintained for 6 hr. In alloxan diabetes brain glycogen was not elevated in spite of the high plasma glucose concentrations. However, administration of insulin to such diabetic animals, together with enough glucose to maintain high plasma levels, resulted in at least a doubling of brain glycogen in 6 hr. Phenobarbital can still increase brain glycogen in diabetic animals. In all of the conditions associated with increased glycogen deposition, increases were found in the ratio of brain glucose to plasma glucose. Cerebral glucose-6-P levels were also increased whereas there were no substantial changes in levels of UDP-glucose or glucose-1,6-diphosphate.