PHYTOCHROME CONTROL OF ROOT GROWTH RATE IN LEMNA SPECIES

Root growth rate was studied in Lemna gibba L. (strains Gl and G3) and L. minor L. in relation to low energy red and far-red light treatments. Far-red treatments inhibited growth rate; inhibition was abolished upon subsequent treatment with red light. These effects can be observed after an 18-hr growth period. This red/far-red photoreversible response suggests that root growth in L. gibba L. and L. minor L. is under phytochrome control.     

THE INTRACELLULAR MEMBRANES OF BLASTOMYCES DERMATITIDIS

Edwards , George A., and Mercedes R. Edwards . (Div. Labs, and Research, N.Y.S. Dept. of Health, Albany.) The intracellular membranes of Blastomyces dermatitidis. Amer. Jour. Bot. 47 (8): 622–632. Illus. 1960.—The yeast cells of Blastomyces dermatitidis have been studied in thin sections with the electron microscope. The cell is multinucleate, and the nuclei are frequently interconnected by their outer limiting membranes. The cell is bordered by a cell wall and the plasma membrane, which may be seen in direct continuity with the nuclear envelope. The cytoplasm contains numerous mitochondria, many profiles of the endoplasmic reticulum, and few multivesicular bodies. The membranes of all the constant cellular components are interconnected. Mitochondria appear to be formed from any of several membrane systems. The micromorphology of the cell suggests efficiency of communication and cytoplasmic mobility.     

Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) parasitizing terrestrial isopods (Isopoda: Oniscoidea)

Summary A new mermithid nematode, Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) was found parasitizing two terrestrial isopods (Isopoda: Oniscoidea) in California. The hosts, Armadillidium vulgare (Latr.) (a pillbug) and Porcellio scaber (Latr.) (a sowbug) represent the first cases of isopods attacked by mermithid nematodes. The genus Thaumamermis can be distinguished from all previously described mermithids by the extremely dimorphic spicules, one being short and broad and the other long and filiform. It has been discovered that the nematodes are infected with an iridiovirus which commonly destroys the isopod hosts. ac]19800917     

Porphyrogenic effects and induction of heme oxygenase in vivo by δ-aminolevulinic acid

The effects of single large doses of the porphyrin-heme precursor ?d-aminolevulinic acid on tissue porphyrins and on δ-aminolevulinate synthase and heme oxygenase, the rate-living enzymes of liver heme synthesis and degradation respectively, were studied in the chick embryo in ovo, in the mouse and in the rat. δ-Aminolevulinic acid treatment produced a distinctive pattern characterized by extensive tissue porphyrin accumulation and alterations in these rate-limiting enzymes in the liver. Repression of basal or allylisopropylacetamide-induced liver δ-aminolevulinate synthase was observed and, in the mouse and the rat, induction of liver heme oxygenase after δ-aminolevulinic acid treatment, in a manner similar to the known effects of hemin on these enzymes. In the chick embryo liver in ovo heme oxygenase was substantially higher than in rat and mouse liver, and was not significantly induced by δ-aminolevulinic acid or other compounds, including hemin, CS₂ and CoCl₂. Levulinic acid, an analogue of δ-aminolevulinic acid, did not induce heme oxygenase in mouse liver. δ-Aminolevunilic acid treatment did not impair ferrochelatase activity but was associated with slight and variable decreases in liver cytochrome P-450. Treatment of chick embryos with a small ‘priming’ dose of 1,4-dihydro-3,5-dicarbethoxycollidine, which impairs liver ferrochelatase activity, accentuated porphyrin accumulation after δ-aminolevulinic acid in the liver. These observations indicate that exogenous δ-aminolevulinic acid is metabolized to porphyrins in a number of tissues and, at least in the liver, to a physiologically significant amount of heme, thereby producing an increase in the size of one or more of the heme pools that regulate both heme systhesis and degradation. It is also possible than when δ-aminolevulinic acid is markedly overproduced in vivo it may be transported to many tissues and re-enter the heme pathway and alter porphyrin-heme metabolism in cells and tissues other than those in which its overproduction primarily occurs.