Continuous culture of suspended plant cells

Summary Continuous culture is an attractive research tool in physiologic and growth and production kinetics research. However, fulfillment of the basic assumptions of continuous culture in the experimental set-up may cause problems. The homogeneity of plant cell cultures and effluent, particularly, may cause problems. This paper presents an experimental set-up which solves these problems and describes the use of this equipment in a study of the growth kinetics of plant cells. Industrial application of the continuous culture of plant cells in the production of secondary metabolites seems to be profitable when compared with batch or fed-batch cultures. However, various problems such as uncoupled product formation and strain instability make fed-batch culture a better choice. Presented in the Session-in-Depth Batch Production and Fermentation at the 1991 World Congress on Cell and Tissue Culture, Anaheim, California, June 16–20, 1991.     

Identification and Distribution of m- and p-Hydroxyphenylacetic Acids in the Brain of the Rat

The m and p isomers of hydroxyphenylacetic acid have been identified and quantitated in whole rat brain and in several regions using a capillary column high resolution gas chromatography–mass spectrometry procedure. Their concentrations were: for m-hydroxyphenylacetic acid (mean ± S.E., number of determinations in parentheses)—whole brain, 2.3 ± 0.3 ng/g (7); hypothalamus, 1.2 ± 0.3 ng/g (5); caudate nucleus, 5.5 ± 0.6 ng/g (5); brain stem, 1.8 ± 0.1 ngig (5); cerebellum, 1.2 ± 0.1 ng/g (5) and the “rest,” 1.7 ± 0.1 ng/g (5); and for p-hydroxyphenylacetic acid–whole brain, 10.6 ± 0.7 ng/g (7); hypothalamus, 4.5 ± 0.1 ng/g (4); caudate nucleus, 28.3 ±1.6 ng/g (5); brain stem, 8.6 ± 0.6 ng/g (5); cerebellum, 8.1 ± 0.4 ng/g (9, and the “rest,” 5.3 ± 0.5 ng/g (5). This heterogeneous distribution parallels closely that exhibited by their respective precursor amines, m- and p-tyramine.     

The antimutagenic effect of selenium on 7,12-dimethylbenz(a)anthracene and metabolites in the amesSalmonella/microsome system

The antimutagenic effect of selenium as sodium selenite, sodium selenate, selenium dioxide, and seleno-methionine was studied in the AmesSalmonella/microsome mutagenicity test using 7,12-dimethylbenz(a)anthracene (DMBA) and some of its metabolites. Selenium (20 ppm) as sodium selenite reduced the number of histidine revertants on plates containing up to 100 μg DMBA/plate. Increasing concentrations of selenium as sodium selenite, sodium selenate, and selenium dioxide up to 40 ppm Se progressively decreased the number of revertants caused by 50 μg DMBA. DMBA and its metabolites 7-hydroxymethyl-12-methylbenz(a)anthracene, 12-hydroxymethyl-7-methylbenz(a)anthracene, and 3-hydroxy-7,12-dimethylbenz(a)anthracene were mutagenic forSalmonella typhimurium TA100 in the presence of an S-9 mixture. Selenium supplementation as Na₂SeO₃ reduced the number of revertants induced by these metabolites to background levels. The antimutagenic effect of inorganic selenium compounds cannot be explained by toxicity of selenium as determined by viability tests withSalmonella typhimurium TA100. Selenium supplementation in all forms examined, except sodium selenate, decreased the rate of spontaneous reversion. Selenium as sodium selenate was slightly mutagenic at concentrations of 4 ppm or less. Higher concentration of Na₂SeO₄ inhibited the mutagenicity of DMBA. The present studies support the anticarcinogenic potential of selenium and indicate that form and concentration are important factors in this trace element's efficacy.     

Isolubimin: A possible precursor of lubimin in infected potato slices

Potato slices treated with spirovetiva-1(10),11-diene-2-one yield lubimin and rishitin within 24 hr. A vetispirane which has not been detected in fungally infected potatoes was also isolated. This compound, isolubimin, appears to be an intermediate in the conversion of the above spirovetivone to lubimin.     

The use of Opalina sudafricana in a biological test for diagnosing disordered metabolism of tryptophan in human subjects

Injections of urine of patients with bladder cancer linked with bilharziasis, simple urinary bilharziasis, ascariasis or ancylostomiasis, induced cyst formation found in Opalina sudafricana when injected into its host Bufo regularis. It is suggested that the carcinogenic tryptophan metabolites present in the injected urine reach the parasites in the recta of the experimental toads and stimulate them to divide mitotically to form small forms which eventually encyst. This test may be of a diagnostic help in detecting any abnormality in tryptophan metabolism in some human patients.     

The derivation and use of biosynthetic incorporation and dilution values

Mathematical expressions governing incorporation and dilution values in a simple, three component biosynthetic system are established and used to track the influence of pathway structure and sampling time on the numerical value of these parameters. A more productive manner of using the incorporation concept is suggested.     

Effects of microbial volatile organic compounds on Ganoderma lucidum growth and ganoderic acids production in Co-v-cultures (volatile co-cultures)

Abstract

Co-v-culture (co-cultivations of physically separated microbes that only interact through the air) systems were designed to investigate the effects of microbial volatile organic compounds (mVOCs) from about 20 different microbes, on a medicinal fungus, Ganoderma lucidum. For more accuracy in co-cultivations, a novel synchronized cultivation approach was tested for culturing G. lucidum. The hyphal growth of G. lucidum and the content of its ganoderic acids (GAs) were measured. In almost all of the co-v-cultures, there was an inhibiting effect on hyphal growth and a promoting effect on GAs contents. In inducing GAs production, Bacillus cereus PTCC 1247 and Pseudomonas aeruginosa UTMC 1404 were the most effective ones, as, compared to control cultures, GAs content increased 2.8 fold. Comparing different co-v-cultivations demonstrated that the concentrations of mVOCs, oxygen, and carbon dioxide were the main players in co-v-cultures. No correlation was found between hyphal growth and GAs production. Strains of the same species imposed totally different effects on hyphal growth or GAs production. This study has investigated the effects of mVOCs on G. lucidum for the first time. Moreover, it suggests that co-v-cultivation may be a promising biotechnological approach to improve the production in G. lucidum.     

Microbial Metabolite Signaling Is Required for Systemic Iron Homeostasis

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Human urine: Epicatechin metabolites and antioxidant activity after cocoa beverage intake

Associations between cocoa consumption in humans, excreted metabolites and total antioxidant capacity (TAC) have been scarcely investigated. The aims of the study were to investigate the epicatechin (( ? )-Ec) metabolites excreted in urine samples after an intake of 40 g of cocoa powder along with the TAC of these urine samples and the relation between both the analyses. Each of the 21 volunteers received two interventions, one with a polyphenol-rich food (PRF) and one with a polyphenol-free food (PFF) in a randomized cross-over study. Urine samples were taken before and during 24 h at 0–6, 6–12 and 12–24 h periods after test intake. The excreted ( ? )-Ec metabolites and the TAC were determined in urine samples by LC-MS/MS and TEAC assay, respectively. The maximum excretion of ( ? )-Ec metabolites and the maximum TAC value were observed in urine samples excreted between 6 and 12 h after PRF consumption. Significance of TAC increase was found in urine samples excreted during 0–6 and 6–12 h (66.6 and 72.67%, respectively, with respect to the 0 h).