scholarly journals Kinetic analysis of N-acylphosphatidylserine accumulation and implications for membrane assembly in Rhodopseudomonas sphaeroides

1982 ◽  
Vol 152 (2) ◽  
pp. 607-615
Author(s):  
B D Cain ◽  
T J Donohue ◽  
S Kaplan
Keyword(s):  
Kinetic Analysis ◽  
Growth Medium ◽  
Metabolic Pathway ◽  
Fold Increase ◽  
Phospholipid Content ◽  
Membrane Biogenesis ◽  
Rhodopseudomonas Sphaeroides ◽  
Intracytoplasmic Membrane ◽  
Phospholipid Transfer ◽  
Cellular Phospholipid

The accumulation of N-acylphosphatidylserine (NAPS) in response to the inclusion of Tris in the growth medium of Rhodopseudomonas sphaeroides strain M29-5 has been examined. In the accompanying paper (Donohue et al., J. Bacteriol. 152:000--000, 1982), we show that in response to Tris, NAPS accumulated to as much as 40% of the total cellular phospholipid content. NAPS accumulation began immediately upon addition of Tris and was reflected as an abrupt 12-fold increase in the apparent rate of NAPS accumulation. We suggest that Tris altered the flow of metabolites through a preexisting and previously unknown metabolic pathway. NAPS accumulation ceased immediately upon the removal of Tris; however, accumulated NAPS remained largely metabolically stable. Importantly, under conditions in which NAPS was not accumulated, the intracytoplasmic membrane was shown to be virtually devoid of newly synthesized NAPS. The significance of this observation is discussed in terms of its physiological implications on phospholipid transfer and membrane biogenesis in R. sphaeroides.

scholarly journals Metabolic Engineering of Saccharomyces cerevisiae for Conversion of d-Glucose to Xylitol and Other Five-Carbon Sugars and Sugar Alcohols

2007 ◽  
Vol 73 (17) ◽  
pp. 5471-5476 ◽  
Author(s):  
Mervi H. Toivari ◽  
Laura Ruohonen ◽  
Andrei N. Miasnikov ◽  
Peter Richard ◽  
Merja Penttilä
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Metabolic Engineering ◽  
Growth Medium ◽  
Fold Increase ◽  
Pichia Stipitis ◽  
Xylitol Dehydrogenase ◽  
Sugar Alcohols ◽  
Pentose Sugar ◽  
Encoding Gene ◽  
Pentose Sugars

ABSTRACT Recombinant Saccharomyces cerevisiae strains that produce the sugar alcohols xylitol and ribitol and the pentose sugar d-ribose from d-glucose in a single fermentation step are described. A transketolase-deficient S. cerevisiae strain accumulated d-xylulose 5-phosphate intracellularly and released ribitol and pentose sugars (d-ribose, d-ribulose, and d-xylulose) into the growth medium. Expression of the xylitol dehydrogenase-encoding gene XYL2 of Pichia stipitis in the transketolase-deficient strain resulted in an 8.5-fold enhancement of the total amount of the excreted sugar alcohols ribitol and xylitol. The additional introduction of the 2-deoxy-glucose 6-phosphate phosphatase-encoding gene DOG1 into the transketolase-deficient strain expressing the XYL2 gene resulted in a further 1.6-fold increase in ribitol production. Finally, deletion of the endogenous xylulokinase-encoding gene XKS1 was necessary to increase the amount of xylitol to 50% of the 5-carbon sugar alcohols excreted.

Induced Root Differentiation in Sycamore Callus

1972 ◽  
Vol 11 (2) ◽  
pp. 319-337
Author(s):  
K. WRIGHT ◽  
D. H. NORTHCOTE
Keyword(s):  
Carbon Source ◽  
Histological Examination ◽  
Growth Medium ◽  
Metabolic Pathway ◽  
Root Hairs ◽  
Physiological Role ◽  
Good Growth ◽  
Active Growth ◽  
Root Differentiation ◽  
The Common

A sycamore callus (S 4) has been isolated and grown on a medium containing salts, vitamins, a casein digest, 2% sucrose and 1 mg/l. NAA. The callus, which would not grow in the absence of the added auxin, was much firmer in texture than a sycamore callus (S 2) isolated in this laboratory in 1958 which has not been induced to differentiate. When kinetin over the range 0.05-0.5 mg/l. was included in the growth medium of S 4 nodules of xylem and phloem were induced within the tissue and roots frequently grew from the surface of the callus. Some roots developed geotropic sensitivity although the majority grew radially outwards from the callus surface. The roots also varied with respect to the number of root hairs they carried. No roots were produced at sucrose concentrations less than 2%, although histological examination revealed extensive xylem and phloem differentiation relative to the amount of growth which had taken place. When sugars other than sucrose were supplied in the medium at a concentration of 3% (w/v) roots were also induced in those calluses where the carbon source had supported good growth. Sucrose, glucose and fructose were identified in the ethanol-soluble extracts of all these calluses. Radioactivity was incorporated into sucrose when S 4 was incubated on a medium containing D-[U-14C]glucose for 24 h. Any sugar which supported growth and differentiation was therefore one which was capable of entering the common metabolic pathway used by the plant for glucose and sucrose. The cells could undergo differentiation so long as the sugar they were supplied with supported active growth and division. The possibility of a physiological role for sucrose is discussed.

scholarly journals Phospholipid transfer between plasma and platelets in vitro

Blood ◽  
1976 ◽  
Vol 48 (2) ◽  
pp. 199-211 ◽  
Author(s):  
JH Joist ◽  
G Dolezel ◽  
JV Lloyd ◽  
F Mustard
Keyword(s):  
Plasma Lipids ◽  
Phospholipid Fatty Acid ◽  
Lipid Extraction ◽  
Phospholipid Content ◽  
Phospholipid Fatty Acid Composition ◽  
Platelet Phospholipid ◽  
Time Intervals ◽  
Phospholipid Analysis ◽  
Phospholipid Transfer

Abstract Washed rabbit platelets were resuspended in plasma in which all of the major phospholipids had been isotopically labeled by injection of 32PO4 into rabbits. At certain time intervals during a 6-hr incubation at 37 degrees C, aliquots were removed from the incubation mixture and the platelets were isolated and subjected to lipid extraction and phospholipid analysis. A continuous rise in platelet non-lipid-bound and lipid-bound radioactivity was observed through-out the incubation period. Two platelet phospholipids, lecithin and lysolecithin, were significantly labeled, whereas little or no labeling of the other phospholipids was found. There was no detectable change in total or individual platelet phospholipid content. At 6 hr, 4% of total platelet phospholipid, 43% of platelet lysolecithin, and 7% of platelet lecithin were labeled. Platelets incubated in plasma from rabbits with diet- induced hyperlipidemia took up and incorporated significantly more label into their phospholipids than did platelets in normal plasma. Labeling of both platelet lysolecithin and lecithin could be due to uptake and metabolism of plasma lysolecithin by platelets. However, labeling of platelet lecithin could at least in part be the result of direct exchange of this phospholipid with the plasma. Uptake and incorporation of endogenous plasma lysolecithin by platelets and, possibly, direct exchanged of platelet lecithin may be important mechanisms in the modification by plasma lipids of platelet membrane phospholipid fatty acid composition and platelet function.

scholarly journals Low-Cost Biodegradation and Detoxification of Textile Azo Dye C.I. Reactive Blue 172 byProvidencia rettgeriStrain HSL1

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Harshad Lade ◽  
Sanjay Govindwar ◽  
Diby Paul
Keyword(s):  
Growth Medium ◽  
Wheat Bran ◽  
Azo Dyes ◽  
Metabolic Pathway ◽  
Azo Dye ◽  
Low Cost ◽  
Agricultural Waste ◽  
Accession Number ◽  
Cost Growth ◽  
Intermediate Metabolites

Present study focuses on exploitation of agricultural waste wheat bran (WB) as growth medium for degradation of textile azo dye C.I. Reactive Blue 172 (RB 172) using a single bacteriumP. rettgeristrain HSL1 (GenBank accession numberJX853768.1). The bacterium was found to completely decolorize 50 mg L−1of dye RB 172 within 20 h at 30 ± 0.2°C under microaerophilic incubation conditions. Additionally, significant reduction in COD (85%) and TOC (52%) contents of dye decolorized medium was observed which suggested its mineralization. Induction in the activities of azoreductase (159%) and NADH-DCIP reductase (88%) provided an evidence for reductive cleavage of dye RB 172. The HPLC, FTIR, and GC-MS analysis of decolorized products confirmed the degradation of dye into various metabolites. The proposed metabolic pathway for biodegradation of RB 172 has been elucidated which showed the formation of 2 intermediate metabolites, namely, 4-(ethenylsulfonyl) aniline and 1-amino-1-(4-aminophenyl) propan-2-one. The acute and phytotoxicity evaluation of degraded metabolites suggests that bacterial strain favors the detoxification of dye RB 172. Thus, WB could be utilized as a low-cost growth medium for the enrichment of bacteria and their further use for biodegradation of azo dyes and its derivatives containing wastes into nontoxic form.

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