Stimulation of sporulation by ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis

Summary Addition of ppApp to Sterlini-Mandelstam medium stimulates sporulation of a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis to the same extent as the effect of 4 amino acids. Mutant cells sporulating in the presence of amino acids also produce 2 phosphorylated nucleotides one of which comigrated with ppApp on PEI thin layer chromatogram.Acknowledgment. This work was supported in part by a grant from Research Corporation, New York, New York.     

Regulation of ppApp synthesis during sporulation of a conditionally asporogenous rifampin mutant ofBacillus subtilis

Summary The intracellular synthesis of ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis stimulated to sporulate in the Sterlini-Mandelstam (SM) medium supplemented with ppApp is negligible and comparable to that of the non-sporulating culture. The formic acid extract from the sporulating culture stimulates sporulation of the mutant in SM medium.This paper was presented at the Annual Meeting of the American Society for Microbiology in Dallas, Texas, in March 1981. This work was supported in part by a grant from Research Corporation, New York, N.Y., USA.     

Inhibition of arginase in sheep brain homogenates by some L-amino acids

Summary The effect of 16 L-amino acids on the activity levels of arginase in sheep brain homogenates was studied. The amino acids leucine, valine, lysine, and ornithine inhibited arginase activity significantly. The other amino acids tested did not show a significant influence on arginase activity. The inhibition was related to the carbon chain length of the amino acids.     

Changes in free amino acid level due to physical and chemical agents in ageing Drosophila.

The effects of gamma rays and caffeine on total free amino acids were assessed in unirradiated and irradiated ageing Drosophila. As age advances, there is a rise in the quantity of free amino acids in untreated males and females. Gamma rays and caffeine strongly reduce the level of free amino acids in both the sexes.     

Changes in the free amino acids of the haemolymph of diapause and non-diapause pupae of the cotton bollworm,Heliothis armigera Hbn. (Lepidoptera: Noctuidae)

Summary The concentration of free amino acids in the haemolymph of non-diapausing and diapausing pupae ofHeliothis armigera was investigated. 20 amino acids were detected in the haemolymph of the studied stages. Asparagine, glutamine, cystine, ornithine, histidine and valine were the predominant free amino acids at all stages. The diapause resulted in increased levels of most of the amino acids.     

Changes in free amino acid level due to physical and chemical agents in ageingDrosophila

Summary The effects of gamma rays and caffeine on total free amino acids were assessed in unirradiated and irradiated ageingDrosophila. As age advances, there is a rise in the quantity of free amino acids in untreated males and females. Gamma rays and caffeine strongly reduce the level of free amino acids in both the sexes.Acknowledgment. The author wishes to thank the Dean, School of life Sciences, Jawaharlal Nehru University, New Delhi-110067, for providing necessary fascilities during the course of this work.     

Control of cell growth: Rag GTPases in activation of TORC1

The target of rapamycin (TOR) is a central regulator controlling cell growth. TOR is highly conserved from yeast to mammals, and is deregulated in human cancers and diabetes. TOR complex 1 (TORC1) integrates signals from growth factors, cellular energy status, stress, and amino acids to control cell growth, mitochondrial metabolism, and lipid biosynthesis. The mechanisms of growth factors and cellular energy status in regulating TORC1 have been well established, whereas the mechanism by which amino acid induces TORC1 remains largely unknown. Recent studies revealed that Rag GTPases play a central role in the regulation of TORC1 activation in response to amino acids. In this review, we will discuss the recent progress in our understanding of Rag GTPase-regulated TORC1 activation in response to amino acids. Particular focus will be given to the function of Rag GTPases in TORC1 activation and how Rag GTPases are regulated by amino acids.     

Emerging knowledge of regulatory roles of <Emphasis Type="SmallCaps">d-</Emphasis>amino acids in bacteria

The d-enantiomers of amino acids have been thought to have relatively minor functions in biological processes. While l-amino acids clearly predominate in nature, d-amino acids are sometimes found in proteins that are not synthesized by ribosomes, and d-Ala and d-Glu are routinely found in the peptidoglycan cell wall of bacteria. Here, we review recent findings showing that d-amino acids have previously unappreciated regulatory roles in the bacterial kingdom. Many diverse bacterial phyla synthesize and release d-amino acids, including d-Met and d-Leu, which were not previously known to be made. These noncanonical d-amino acids regulate cell wall remodeling in stationary phase and cause biofilm dispersal in aging bacterial communities. Elucidating the mechanisms by which d-amino acids govern cell wall remodeling and biofilm disassembly will undoubtedly reveal new paradigms for understanding how extracytoplasmic processes are regulated as well as lead to development of novel therapeutics.     

Free amino acids in motor cortex of amyotrophic lateral sclerosis.

Free amino acids were estimated quantitatively in the motor cortex from 3 patients with amyotrophic lateral sclerosis (ALS) and 11 control subjects. Among 7 amino acids which showed statistically significant changes, taurine was the only one which was increased constantly and most markedly in the motor cortex of all the 3 ALS cases. It was suggested that the metabolism of sulfur amino acids might be affected in comparatively early stages of ALS.     

Influence of medium amino acids on the ouabain sensitive and insensitive 86Rb+-fluxes in HeLa cells

Components of the 86Rb+-influx in HeLa cells were investigated in Joklik minimal essential medium, or in Earle's balanced salt solution with and without medium amino acids. The presence of amino acids led to the stimulation of the ouabain sensitive 86Rb+-uptake and inhibition of the diuretic-sensitive and residual 86Rb+-fluxes. These results show that the presence of amino acids is an important regulator of the K+/Rb+-fluxes under normal conditions in growth medium.     

Identification of uncommon amino acids in the lentil seed (Lens culinaris Med.).

The fraction of the free basic amino acids in the lentil seed was shown to contain gamma-hydroxyarginine, gamma-hydroxyornithine and homoarginine besides the common amino acids. Similar distribution was found in 5 varieties of lentil, with hydroxyarginine and arginine dominating. The significance of these findings with regard to chemotaxonomy and lentil consumption is discussed.     

Free amino acid composition of the intestinal contents,intestinal cells and hemolymph ofPhilosamia cynthia larvae

Summary Free amino acid composition of the intestinal contents, intestinal cells and hemolymph has been determined in larvae of the mothPhilosamia cynthia. From the hemolymph/lumen concentration ratio, an active transport could be inferred for neutral and basic amino acids. The values of cell/lumen and hemolymph/cell ratios suggested that the active step in the transport mechanism could be localized at the luminal pole of the enterocyte for neutral amino acids (except aromatic amino acids) and at the basolateral pole of the enterocyte for basic amino acids (except arginine).This work was supported by grants from Italian Consiglio Nazionale delle Ricerche and from Ministero della Pubblica Istruzione, Rome. The authors are indebted to Prof. V. Capraro for helpful discussion.     

Free amino acids in motor cortex of amyotrophic lateral sclerosis

Summary Free amino acids were estimated quantitatively in the motor cortex from 3 patients with amyotrophic lateral sclerosis (ALS) and 11 control subjects. Among 7 amino acids which showed statistically significant changes, taurine was the only one which was increased constantly and most markedly in the motor cortex of all the 3 ALS cases. It was suggested that the metabolism of sulfur amino acids might be affected in comparatively early stages of ALS.Acknowledgments. The authors are grateful to Dr M. Uono, Department of Neurology, Tokyo Metropolitan Hospital of Fuchu, and Dr K. Hirayama, Department of Neurology, Brain Research Institute, School of Medicine, Chiba University, for their generous cooperation.     

Free amino acids in some tissues of marine crustacea

Summary Free amino acids contained in extracts of crustaceans were separated and determined quantitatively by ion exchange chromatography. In the hepatoprancreas of the brachyuran crustaceanCarcinus maenas, glycine, arginine, proline and alanine constituted 78.7% of the total amino acid pool. InEriphia spinifrons andMaja verrucosa, glycine, alanine, lysine and leucine comprised 54.9–66.9% of the total content. In the muscle tissue of the macruran crustaceaPalaemon, glycine, arginine, proline and alanine were the most common free amino acids and comprised 70–95% of the total content. The high concentrations of some amino acids in tissues of crustaceans may play a role in intracellular osmotic regulation and also in the maintenance of ionic hydrogen concentration.Acknowledgments. The author wishes to thank Mr R. Mari for his skillful help in the amino acid analyses and Miss G. Princivalli for typing the mansucript.     

Uptake of L-glutamate and L-aspartate in neurones and glial cells of cultured human and rat spinal cord.

Autoradiographic investigations on the uptake of L-glutamate and L-aspartate have shown that the amino acids were taken up by neurones as well as by glial cells of cultured human and rat spinal cord. The activity of glutamate and aspartate varied considerably between individual neurones, whereas glial cells showed a more even distribution of the labelled amino acids. Our results suggest that both neurones and glial cells are involved in the uptake of amino acid transmitters.     

Conserved amino acids participate in the structure networks deputed to intramolecular communication in the lutropin receptor

The luteinizing hormone receptor (LHR) is a G protein-coupled receptor (GPCR) particularly susceptible to spontaneous pathogenic gain-of-function mutations. Protein structure network (PSN) analysis on wild-type LHR and two constitutively active mutants, combined with in vitro mutational analysis, served to identify key amino acids that are part of the regulatory network responsible for propagating communication between the extracellular and intracellular poles of the receptor. Highly conserved amino acids in the rhodopsin family GPCRs participate in the protein structural stability as network hubs in both the inactive and active states. Moreover, they behave as the most recurrent nodes in the communication paths between the extracellular and intracellular sides in both functional states with emphasis on the active one. In this respect, non-conservative loss-of-function mutations of these amino acids is expected to impair the most relevant way of communication between activating mutation sites or hormone-binding domain and G protein recognition regions.     

Preferential hydrophobic interactions are responsible for a preference of D-amino acids in the aminoacylation of 5'-AMP with hydrophobic amino acids.

We have studied the chemistry of aminoacyl AMP to model reactions at the 3' terminus of aminoacyl tRNA for the purpose of understanding the origin of protein synthesis. The present studies relate to the D, L preference in the esterification of 5'-AMP. All N-acetyl amino acids we studied showed faster reaction of the D-isomer, with a generally decreasing preference for D-isomer as the hydrophobicity of the amino acid decreased. The beta-branched amino acids, Ile and Val, showed an extreme preference for D-isomer. Ac-Leu, the gamma-branched amino acid, showed a slightly low D/L ratio relative to its hydrophobicity. The molecular basis for these preferences for D-isomer is understandable in the light of our previous studies and seems to be due to preferential hydrophobic interaction of the D-isomer with adenine. The preference for hydrophobic D-amino acids can be decreased by addition of an organic solvent to the reaction medium. Conversely, peptidylation with Ac-PhePhe shows a preference for the LL isomer over the DD isomer.     

Characterization of free amino acids in the hemolymph ofAchaea janata L. larvae (Lep.Noctuidae)

Summary 19 free amino acids were separated and quantified from the hemolymph of 5th instar larvae of the mothAchaea janata. Proline, histidine, threonine/glutamine/asparagine, lysine, valine and serine were the predominant amino acids in the hemolymph. Changes in amino acid concentration are discussed in relation to metabolic and other physiological activities.Acknowledgment. Y.P. Ramdev wishes to thank the Director, Indian Agricultural Research Institute, New Delhi, India for providing Senior Research Fellowship.     

Amino acid transport by small and large intestine of newborn pig

Summary Unidirectional fluxes of different amino acids have been determined across newborn pig small intestine and colon. The systems responsible for amino acid transport are present in the same proportion in both tissues. Colonic transport of amino acids appears to represent a transient overspill function of the small intestine.     

Properties of gamma-glutamyltranspeptidase, and glutathione levels in rat mammary gland

gamma-Glutamyltranspeptidase activity and glutathione levels were studied in rat mammary gland during the lactogenic cycle; both increased during mid-lactation. The enzyme's specific activity with several amino acids showed that glutamine and methionine were the best substrates. Maleate decreased the transpeptidation reaction and increased the hydrolytic activity. These results suggest that gamma-glutamyltranspeptidase from the mammary gland is similar to the enzyme described in other tissues in relation to these properties and the physiological role proposed in amino acids transport.