Cholinergic differentiation of rat sympathetic neurons in culture: effects of factors applied to distal neurites.

Cholinergic properties are induced in sympathetic neurons by several factors applied to entire neurons in culture. Evidence from work with the rat sweat gland model indicates that factors located in target tissues can induce cholinergic differentiation in vivo. We now report that when leukemia inhibitory factor (LIF), heart cell-conditioned medium (HCCM), or dermal fibroblast-conditioned medium (DFCM) is applied to only distal neurites in compartmented cultures of rat sympathetic neurons, the neurons exhibit an increase in specific choline acetyltransferase activity and a concomitant decrease in levels of tyrosine hydroxylase. LIF, HCCM, and DFCM also induce neurite fasciculation, thus suggesting an additional role of cholinergic switching factors in regulating axon-axon and/or axon-substrate adhesion. These results demonstrate that rat sympathetic neurons have the cellular machinery to respond to cholinergic differentiation cues located in peripheral targets, analogous to the response to nerve growth factor.     

Cloning and sequencing of a cDNA encoding 2,3-bisphosphoglycerate-independent phosphoglycerate mutase from maize. Possible relationship to the alkaline phosphatase family.

The primary sequence of maize 2,3-bisphosphoglycerate-independent phosphoglycerate mutase was deduced from cDNAs isolated from maize cDNA libraries by screening with specific antibodies to the cofactor-independent enzyme and from a maize genomic clone. The genomic clone provided the 5'-nucleotide sequence encoding the N-terminal amino acids which could not be obtained from the cDNA. Confirmation that the nucleotide sequence was for the cofactor-independent phosphoglycerate mutase was obtained by sequencing the peptides generated from cyanogen bromide cleavage of the purified protein. This is the first report of the amino acid sequence of a 2,3-bisphosphoglycerate cofactor-independent phosphoglycerate mutase, which consists of 559 amino acids and is twice the molecular size of the mammalian cofactor-dependent enzyme subunit. Analysis of the cofactor-independent phosphoglycerate mutase amino acid sequence revealed no identity with the cofactor-dependent mutase types. Northern blot analysis confirmed this difference since the maize cofactor-independent phosphoglycerate mutase cDNA did not hybridize with mRNA of the cofactor-dependent mutase. The lack of amino acid identity between cofactor-dependent and -independent enzymes is consistent with their different catalytic mechanisms and suggests that both enzymes are unrelated evolutionarily and arose from two independent ancestral genes. However, a constellation of residues which are involved in metal ion binding in various alkaline phosphatases is conserved in the maize cofactor-independent phosphoglycerate mutase, which suggests that the enzyme is a member of the alkaline phosphatase family of enzymes.     

Mechanisms towards compensation of long-term haemopoietic injury in mice after 5 Gy irradiation:In vivo andin vitro enhancement of superoxide anion production by granulocytes

This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes.     

The photoreaction center of Rhodospirillum rubrum mutant strain F24.1

Rhodospirillum rubrum strain F24.1 is a spontaneous revertant of nonphototrophic mutant F24 derived from wild-type strain S1. Strain F24 shows no detectable photochemical activity and contains, at most, traces of the photoreaction center polypeptides. Strain F24.1 has a phototrophic growth rate close to that of the wild-type strain (Picorel, R., del Valle-Tascón, S. and Ramírez, J.M. (1977) Arch. Biophys. Biochem. 181, 665–670) but shows little photochemical activity. Light-induced absorbance changes in the near-infrared, photoinduced EPR signals and ferricyanide-elicited absorbance changes indicate that strain F24.1 has a photoreaction center content of 7–8% as compared to strain S1. Polyacrylamide gel electrophoresis of isolated F24.1 chromatophores shows the photoreaction center polypeptides to be present in amounts compatible with this value. Photoreaction center was prepared from strain F24.1 and showed no detectable difference with that of strain S1. It is concluded that strain F24.1 photosynthesis is due entirely to its residual 7–8% of typical photoreaction center.     

Biosynthesis of candicidin by phosphate-limited resting cells ofStreptomyces griseus

Summary A phosphate-limited resting cell system ofStreptomyces griseus in a synthetic medium has been developed in which biosynthesis of the polyene macrolide, candicidin, is linear for at least 36 h without cell growth. Glucose and to a lesser degree sucrose, but not lactose, support antibiotic synthesis. Glucose is utilized at a constant rate for antibiotic synthesis without affecting mycelial dry weight. Acetate and propionate, the building units of the macrolide aglycone, stimulate candicidin biosynthesis in cultures supplemented with glucose but do not support its synthesis in the absence of glucose. Maximal stimulation of candicidin biosynthesis was produced by 40 mM propionate or 250 mM acetate. The biosynthetic intermediate, methyl malonate, and the analog, 1-propanol, were more stimulatory than propionate at the same concentration.     

Properties of spinach chloroplast fructose-1,6-diphosphatase

Photosynthetic fructose-1,6-diphosphatase (FDPase) fractions I and II, earlier purified from spinach leaves, show a similar amino acid composition, with the exception of a higher glutamic acid content in the latter. In both fractions glutamic and aspartic acids are the main amino acids. pH activity profiles of fractions I and II are similar, with optima at 8·65–8·70, both showing a high specificity for fructose- 1,6-diphosphate. These two fractions are Mg²⁺-dependent for activity, with an Optimum Mg²⁺ concentration of 10 mM in standard conditions, which shifts to 5 mM when the MG²⁺/EDTA ratio is increased to 10; Mn²⁺ and Co²⁺ are slightly active. EDTA enhances FDPase activity slightly, with an optimum at 0·4–0·8 mM. Cysteine has no activating effect, and acts as an inhibitor above 10 mM. Both I and II have an optimum substrate concentration of 4 mM, and the substrate inhibits at concns above this value. Kinetic velocity curves are sigmoidal, with the concave zone located in the range of physiological substrate concns. (Hill coefficient 1·75 for both). This suggests a strong regulatory role of fructose-1,6-diphosphate. K_m values are 1·4 × 10⁻³ M (fraction I) and 1·1 × 10⁻³ M (fraction II). The highest activity rate occurs at 60°, in accordance with the high thermostability of both fractions; the activation energies are 14·3 kcal/mol (fraction I) and 13·0 kcal/mol (fraction II).     

The control by respiration of the uptake of α-methyl glucoside in Escherichia coli K12

The uptake of methyl α-d-glucopyranoside (α-MG) by Escherichia coli K12 was decreased by the addition of substrates which stimulated the rate of oxygen consumption by the cells. The inhibition, which occurred only at non-saturating concentrations of α-MG, was not the result of a stimulation of the rate of exit of intracellular α-MG, and was abolished by the presence of carbonyl cyanide m-chlorophenylhydrazone or sodium azide. Since those drugs inhibit energy conservation at the respiratory chain and did not alter significantly the rate of oxygen consumption under the conditions for the assay of α-MG uptake, it appears that the inhibition of the transport system by respirable substrates is mediated by some form of energy derived from respiration.     

Single-cell transcriptomic atlas of primate cardiopulmonary aging

Aging is a major risk factor for many diseases,especially in highly prevalent cardiopulmonary comorbidities and infectious diseases including Coronavirus Diseas...