A new species of Rhynchoidomonas Patton, 1910 (Kinetoplastida: Trypanosomatina) from Operophtera brumata (Lepidoptera: Geometridae)

Summary A new species of Rhynchoidomonas Patton was observed in a single adult male winter moth, Operophtera brumata (L.) from England. Intracellular amastigotes, and extracellular epimastigotes and trypomastigotes with an undulating membrane and free flagellum, were present. All stages had a large, reniform kinetoplast. As transmission of the flagellate between generations of winter moths by ingestion of infected faeces is a virtual impossibility, it is suggested that the flagellate's true host may have been a dipteran parasitoid and that an egg, surface-contaminated with the flagellate, was oviposited into or ingested by a winter moth larva. If the parasitoid had died, this flagellate infection could have been carried over to the adult moth. ac]19830601     

Alpha-chloralose suppression of neuronal activity

Alpha-chloralose, an anesthetic agent widely used in neurophysiologic studies, caused a significant and long-lasting suppression of single neuron activity recorded from two areas of the central nervous system in decerebrate cats. A 50 mg/kg dose (an average anesthetic dose used in many neurophysiologic studies) caused suppression of spontaneous and evoked activity of neurons in the dorsal horn of the spinal cord and greater suppression of neurons in the nucleus reticularis gigantocellularis (NRGC) of the medial medullary reticular formation. Many researchers are of the opinion that alpha-chloralose causes less suppression of the central nervous system (CNS) than other commonly used anesthetic agents. The neuronal suppression recorded in this study appears similar in many ways to suppression caused by other anesthetic agents in the same two areas of the CNS. The results of the present study suggest that alpha-chloralose may be capable of producing significant suppression of neurons in the dorsal horn of the spinal cord and NRGC. Its ability to influence other areas of the CNS should not be inferred from these results, but the data do indicate the importance of evaluating the effects of anesthetics upon neurophysiologic systems under study.     

Differentiation of promyelocytic (HL-60) cells into mature granulocytes: mitochondrial-specific rhodamine 123 fluorescence

Rhodamine 123, a fluorescent dye which binds as a result of the transmembrane potential, was used to stain the mitochondria of HL-60 cells, a cell line established from human promelocytic leukemia cells. The DMSO-induced differentiation of promyelocytic cells into mature granulocytes caused a fourfold decrease in fluorescence intensity that paralleled the disappearance of S-phase and G2M cells. This suggests that upon myeloid differentiation whereby the cells enter an irreversible quiescent state, the mitochondrial mass of the cells has decreased. This suggestion is corroborated by electron microscopy, which shows a decrease in the number of mitochondria, and by decreases in total mitochondrial protein and cytochrome oxidase activity. The respiratory rate of isolated mitochondria did not change, suggesting that the transmembrane potential remained the same. Undifferentiated cells in exponential phase of growth exhibit an intracellular heterogeneity of fluorescence intensity. This heterogeneity appears to have a cell age basis, as late S/G2M cells, obtained by centrifugal elutriation, yielded twice the fluorescence intensity of early G1 cells.     

Studies of activating and nonactivating metal ion binding to yeast enolase

Measurements of binding of certain divalent cations to yeast apoenolase were made using a pH-meter, chromatography, a divalent cation electrode, and ultrafiltration. The binding of the activating metal ions Mg2+ and Co2+ and the nonactivator Ca2+ were studied as functions of the presence or absence of substrate/product, phosphate, and fluoride or level of Tb3+. The data suggest phosphate and fluoride increase Mg2+ binding but not Ca2+ binding. Substrate/product appears to increase Ca2+ binding as well as that of Mg2+ and Co2+. In the presence of substrate, Co2+ binding was 5-6 mol/mol dimer. In the absence of substrate/product, Tb3+ reduced Co2+ binding from 4 mol/mol to 2. These data are interpreted in terms of binding to "conformational," "catalytic" (substrate/product dependent), and "inhibitory" sites. Measurements of Tb3+ fluorescence quenching by Co2+ suggested that the distance between "conformational" sites on the two subunits was large, while the distance between "conformational" and "inhibitory" sites was ca. 17 +/- 4 A. Potentiometric titrations of apoenzyme with Ca2+ and Mg2+ showed that the metal ions produced the same proton release in the presence or absence of substrate/product. If phosphate and fluoride were present, then more protons were released if Ca2+ was the titrant rather than Mg2+, suggesting a difference in ionization state in the complex with the activating metal. Electron paramagnetic resonance studies of Co2+ binding to the various sites in the enzyme are presented. The Co2+ bound to all three sites appears to be high spin, consistent with a preponderance of oxyligands in an octahedral environment. Substrate, citrate, and a strongly binding substrate analogue strongly enhance the hyperfine structure of conformational Co2+. This is interpreted as the result of a change in interaction of an axial ligand to conformational Co2+ produced by carbon-3 of substrate or analogue.     

Pyruvate Kinase of Streptococcus lactis

The kinetic properties of pyruvate kinase (ATP:pyruvate-phosphotransferase, EC 2.7.1.40) from Streptococcus lactis have been investigated. Positive homotropic kinetics were observed with phosphoenolpyruvate and adenosine 5′-diphosphate, resulting in a sigmoid relationship between reaction velocity and substrate concentrations. This relationship was abolished with an excess of the heterotropic effector fructose-1,6-diphosphate, giving a typical Michaelis-Menten relationship. Increasing the concentration of fructose-1,6-diphosphate increased the apparent V_max values and decreased the K_m values for both substrates. Catalysis by pyruvate kinase proceeded optimally at pH 6.9 to 7.5 and was markedly inhibited by inorganic phosphate and sulfate ions. Under certain conditions adenosine 5′-triphosphate also caused inhibition. The K_m values for phosphoenolpyruvate and adenosine 5′-diphosphate in the presence of 2 mM fructose-1,6-diphosphate were 0.17 mM and 1 mM, respectively. The concentration of fructose-1,6-diphosphate giving one-half maximal velocity with 2 mM phosphoenolpyruvate and 5 mM adenosine 5′-diphosphate was 0.07 mM. The intracellular concentrations of these metabolites (0.8 mM phosphoenolpyruvate, 2.4 mM adenosine 5′-diphosphate, and 18 mM fructose-1,6-diphosphate) suggest that the pyruvate kinase in S. lactis approaches maximal activity in exponentially growing cells. The role of pyruvate kinase in the regulation of the glycolytic pathway in lactic streptococci is discussed.     

Effect of LSD on mitotic and meiotic plant chromosomes

LSD was found to induce chromosomal aberrations in root tip cells of Allium cepa, Hordeum vulgare and Secale cereale. Aberrations occurred in the form of chromatid and isochromatid breaks with most of these breaks failing to rejoin. The distribution of chromosome breaks was not uniform over the length of chromosomes, and a majority of the breaks were localized at the centromeric regions. For a given dose of LSD (30 g/ml), onion appeared to be more susceptible than barley or rye. The diploid and tetraploid rye used in the study showed no appreciable difference in sensitivity to LSD treatment. — A preliminary study on meiotic chromosomes in LSD-treated diploid rye revealed the presence of univalents, chromosome breaks and fragments, suggesting that LSD can induce meiotic abnormalities in plant material.Contribution from the Department of Agronomy, University of Kentucky. The investigation reported in this paper (73-3-75) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director.     

Studies on the incorporation of labelled sulphate into cells and cell-free extracts of Nitrosomonas europaea

Summary The incorporation of [³⁵S]sulphate was followed into the washed cell suspensions of Nitrosomonas europaea. Thus bound sulphate, sulphite, sulphide, cysteine, glutathione, homocysteine and methionine were found in the ethanol soluble fraction as well as in the residual hydrolysed protein fraction. Cysteic acid, methionine sulphoxide and methionine sulphone were detected in the residual protein. The reaction between sulphydryl groups and N-ethylmaleimide has been successfully used to stabilize the thiol compounds in cell-extracts and the derivatives thus obtained were separated by paper chromatography. As in other microorganisms, sulphate is first activated by ATP in Nitrosomonas before it is reduced. The formation of APS and PAPS has been studied. A pathway for the incorporation of [³⁵S]sulphate is proposed.Abbreviations POPOP 1,4-bis-(5-phenyloxazolyl-2)-benzene - PPO 2,5-diphenyloxazole - APS adenosine-5-phosphosulphate - PAPS adenosine-3-phosphate 5-phosphosulphate - ATP adenosine triphosphate - DNA-ase deoxyribonuclease - NEM N-ethylmaleimide - TCA trichloro-acetic acid - GSH glutathione