Differential amino acid utilization by Chlamydia psittaci (strain guinea pig inclusion conjunctivitis) and its regulatory effect on chlamydial growth

The effect of omission of individual amino acids from growth medium on the multiplication of Chlamydia psittaci (strain guinea pig inclusion conjunctivitis) in cycloheximide-treated McCoy cells has been examined. Marked differences were observed in the amounts of particular amino acids required for normal chlamydial multiplication: omission of either leucine, phenylalanine or valine completely inhibited multiplication, whereas absence of any one of another 10 amino acids had no effect on numbers of cells infected. Threshold concentrations of 80, 80 and approx. 8 nmol ml-1 for leucine, valine and phenylalanine, respectively, were needed for normal chlamydial multiplication. These requirements could not be related either to unusually high content in the whole organism, to degradation in the medium, or, from studies with leucine, to deficient association of leucine with host cells. Leucine deprivation at late stages of the developmental cycle also appeared to regulate multiplication. Possible mechanisms responsible for these effects are discussed.     

Oxocarboxylic acids, pyridine nucleotide-linked oxidoreductases and serum factors in regulation of cell proliferation

When serum is made rate-limiting for clonal multiplication of human diploid fibroblasts, the presence of a 2-oxocarboxylic acid in the medium becomes essential. The requirement is independent of the 20 amino acids and glucose. Glyoxylic, pyruvic, 2-oxoglutaric, and oxalacetic acids are most effective. The types of 2-oxocarboxylic acids that support multiplication are oxidized substrates for several, pyridine nucleotide-linked intracellular oxidoreductases. The requirement is not satisfied by carboxylic acids, oxidized substrates for oxidoreductases that are not lniked to pyridine nucleotides, or by nonspecific electron acceptors. The quantitative requirement for 2-oxocarboxylic acids in cell multiplication is markedly affected by the concentration of serum proteins in the medium. Therefore, 2-oxocarboxylic acid metabolism may be related to the mechanism by which serum growth factors regulate cell multiplication.     

Amoeba-bacteria relationship: Factors in the bacterial lipids supporting the growth of axenicEntamoeba histolytica

Live bacteria in modifiedDiamond’s axenic medium did not support growth ofEntamoeba histolytica. Cysteine hydrochloride, required for the multiplication of amoeba, was broken down by live bacteria and toxic substances were produced which were lethal for amoebae. Monoxenic and xenic cultures ofaxenically grownE. histolytica could be established in Boeck and Drbohlav medium with bacteria and rice starch. Bacterial lipids prepared from 15 human intestinal bacteria supported growth and multiplication ofE. histolytica in axenic medium. In a pilot experiment using lipids ofStreptococcus faecalis, free fatty acids did stimulate the multiplication of amoebae. When total lipids of this bacteria were fractionated into neutral lipids and phospholipids by chromatography and used, neither fraction was found to stimulate growth. Free fatty acids prepared by chemical hydrolysis of the total lipids, neutral lipids and phospholipids stimulated growth ofE. histolytica, The sterols present in the bacterial lipids (neutral lipids or non-saponifiable fractions) stimulated growth of amoebae. It was found thatE. histolytica is incapable of liberating fatty acids from di- or triglyceridesof phospholipids and the multiplication of the organism is stimulated by the presence of free fatty acids and sterols (cholesterol).     

The amino acid sequence of the light chain of human high-molecular-mass kininogen

The complete amino acid sequence of the light chain of human high-molecular-mass kininogen has been determined. The peptide chain contains 255 amino acid residues. The half-cystine, which forms the disulfide bridge to the heavy chain, was identified in position 225. Nine carbohydrate attachment sites were found. All carbohydrate side chains are O-glycosidically linked. Alignment of the present sequence with the bovine kininogen light chain sequence shows a high degree of homology, except for an extension of 22 amino acids within the histidine-rich part of the sequence. The histidine-rich region may have arisen by gene multiplication during evolution.     

Regulation of phenylalanine oxidase synthesis in Proteus mirabilis.

Cells of Proteus mirabilis could oxidize L-phenylalanine to phenylpyruvate only when grown in the presence of a number of amino acids, particularly, L-alanine, L-asparagine, L-glutamate, and L-glutamine. Production of phenylalanine oxidase was slowly lost upon growth in a minimal medium containing ammonium ions as a nitrogen source but was reversed by the addition of casein hydrolysate. Oxidase activity as well as a phenylalanine-dichlorophenolindophenol (DCIP) reductase activity increased in P. mirabilis only during cell multiplication. Both rifampin and nalidixic acid caused inhibition of oxidase synthesis. A phenylalanine-active transport was found to be operative when bacteria were grown in the absence of added amino acids. After anaerobic growth, cells of P. mirabilis had lost their ability to carry the phenylalanine oxidase reaction when assayed in the presence of air, and nitrate could not be used as an electron acceptor for the oxidation of phenylalanine. However, some phenylalanine-dichlorophenolindophenol reductase activity was still present in anaerobic bacteria at the early stage of cell multiplication.     

Limitation of phage multiplication by microbes of the genus Bordetella

Possible causes limiting the multiplication of Bordetella phages or inducing their restriction, such as the influence of lysogenic immunity and the restriction-modification (R-M) system or the incompatibility of the receptor apparatus, have been studied. The limitation of the multiplication of phages by some B. bronchiseptica and B. pertussis strains has been shown to be due to the presence of the R-M system and lysogenic immunity. In five B. bronchiseptica strains and two B. pertussis strains site-specific endonucleases (restrictases) with Hind III specificity have been detected. One B. bronchiseptica strain without the R-M system has been detected. B. bronchiseptica strains producing site-specific endonucleases are practically nonpathogenic for humans, grow in common culture media and selectively produce only one restrictase, type Hind III, which guarantees from the admixture of other specific endonucleases. The B. parapertussis strains under study (altogether 100 strains) have not been found to limit the multiplication of Bordetella test phages. The absence of site-specific endonucleases has also been confirmed biochemically. These strains are recommended as indicator strains for the multiplication of Bordetella phages.     

Survival of Tetrahymena thermophila at Low Initial Cell Densities. Effects of Lipids and Long-Chain Alcohols

ABSTRACT. Cells of the ciliate Tetrahymena thermophila failed to establish cultures in lipid-free standard synthetic nutrient medium if the initial population density was 250 cells per ml or less. These cells died within 10 h, but were saved and formed dense cultures if their medium was supplemented with 10 μg per ml of either certain phospholipids, 1,2-di-, 1-monoglycerides, fatty acids, long-chain alcohols, or sterols. Cell multiplication was followed in cultures in which the standard synthetic medium was supplemented with a selection of the compounds listed above. It was observed that the cells in the supplemented cultures in their exponential phases of growth had about the same average doubling times as control cells starting multiplication at 10-fold higher initial cell densities in lipid-free medium. These cells have been grown for decades in lipid-free synthetic nutrient media at short (ca. two-three h) doubling times. Therefore lipids have been considered nutritionally non-essential for growth and multiplication of these cells. We propose that those compounds that rescue the cells at low cell densities act as "proliferation signals," sensu lato . This effect of lipids and long-chain alcohols has so far remained unnoticed.     

Ecosystem services,sustainability and thermodynamic indicators

It is proposed to calculate the value of ecosystem services by the annual increase of work capacity or eco-exergy. The annual increase of biomass for various ecosystems is known. By multiplication of the biomass increase by the average content of information as Kullbach's measure of information, in the various ecosystems, the eco-exergy or total work capacity is obtained. An economic value can be found by multiplication of the cost of work, which is about 1 EURO-cent per MJ. A comparison of this value with the values found by Costanza et al. (1997) shows that the value based upon the total work capacity is much higher. The ratio between the two economic values have been found for the various ecosystems. It has been found that the ratio is lower the more an ecosystem by a wide range of application possibilities is utilized. The ecosystems have been divided in five classes according to the ratio and thereby in accordance to our utilization of the total work capacity of various ecosystems.     

Characteristics of the tissue population cycle of shigellae

In experiments on human fetal intestinal explants infected with shigellae the specific multiplication rate of these infective agents, found to be 0.026, and the maximum level of their accumulation in erythrocytes, reaching 22-36 microbes per cell, have been determined. These phenomena can be observed after at least 3-hour incubation and end in the release of the infective agents from the affected area with shedding epithelial elements (villi). Shigellae, aggregated in the shed villi easily adhering to the unaffected mucosa, ensure the intensive invasion of the epithelium, which leads to the continuation of the process. The regularity thus revealed indicates that the population cycle of the development of shigellae is limited by short intervals of 3-4 hours. During these intervals the repeated invasion and the release of shigellae, together with the shed epithelium, into the chyme-containing intestinal cavity occur. The conditions for the multiplication of shigellae and their specific multiplication rate in chyme are minimal (0.016).     

Effect of RNA nucleotides on Shigella biology

Sodium nucleinate and its mononucleotides have been found capable of stimulating the multiplication and virulence of shigellae, as well as their sensitivity to antibiotics, in cultures grown in nutrient media.     

High similarity between flanking regions of different microsatellites detected within each of two species of Lepidoptera: Parnassius apollo and Euphydryas aurinia

Microsatellite flanking regions have been compared in two butterfly species. Several microsatellite flanking regions showed high similarity to one another among different microsatellites within a same species, but very few similarities were found between species. This can be the consequence of either duplication/multiplication events involving large regions containing microsatellites or of microsatellites imbedded in minisatellite regions. The multiplication of microsatellites might also be linked to mobile elements. Furthermore, crossing over between nonhomologous microsatellites can lead to the exchange of the flanking regions between microsatellites. The same phenomenon was observed in both studied butterfly species but not in Aphis fabae (Hemiptera), which was screened at the same time using the same protocol. These findings might explain, at least partially, why microsatellite isolation in Lepidoptera has been relatively unsuccessful so far.     

Localization of domains within the Drosophila Ref(2)P protein involved in the intracellular control of sigma rhabdovirus multiplication.

The ref(2)P gene of Drosophila melanogaster interferes with sigma rhabdovirus multiplication. This gene is highly variable, and the different alleles are considered permissive or restrictive according to their effects on virus replication. In all cases, the mechanisms involve intracellular interactions between the sigma virus and Ref(2)P proteins. We showed that the N-terminal domain of the Ref(2)P protein was required for its activity in vivo. The protein was inactive in the null p(od)2 mutant when its first 82 amino acids were deleted. The p delta n gene was constructed so that the first 91 amino acids coded for by the restrictive alleles could be expressed in vivo. It was active in a transformed line. This sequence was sufficient to impart a restrictive phenotype to an adult D. melanogaster fly after it was injected with the virus. However, the truncated protein expressed by p delta n did not have an effect on the hereditary transmission of the sigma virus to the offspring of the infected flies, even though it contained the restriction site. The native Ref(2)P protein has been previously shown to have conformation-dependent epitopes common with some of those of the viral N protein. We demonstrated the following. (i) These epitopes were found in a domain of the Ref(2)P protein distinct from the site involved in restriction. (ii) They were modified in the N protein of the haP7 sigma virus mutant selected as being adapted to the restrictive alleles of the ref(2)P gene; only one mutation in the N gene, leading to an amino acid substitution, distinguished the haP7 mutant from the original virus. (iii) The virus strains partially or totally adapted to the effects of the full restrictive protein expressed by pp were always found to multiply to a lesser extent in the presence of the protein expressed by p delta n. These data suggest that two distinct domains of the Ref(2)P protein are involved in the control of sigma virus multiplication.     

In vitro root induction in axillary microshoots of Quercus robur L.

Whilst considerable efforts have been made to optimise shoot multiplication and rooting in oak, little attention has been paid to the impact of conditions used for multiplication on subsequent root formation. An optimised technique for rooting of oak microshoots has been developed to assess the effect of cytokinin treatments applied to shoot multiplication cultures on the subsequent rooting of microshoots. We found IBA to be more effective at inducing root formation in microshoots than NAA. Efficient rooting of oak microshoots (80%) was achieved after 35 days on medium supplemented with 1.0 mg litre^-1 IBA. Lower concentrations of IBA reduced the frequency of root formation and significantly increased the time taken for microshoots to form roots. High concentrations of IBA (3.0 mg litre^-1) produced similar rooting frequencies but with significantly increased numbers of roots formed by each microshoot. However, high concentrations of IBA stimulated the production of basal callus. Rooting of microshoots was unaffected by the concentration of BA used during shoot multiplication, although basal callusing was greater in microshoots taken from multiplication medium supplemented with the highest concentration of BA (1.0 mg litre^-1) and rooted on medium supplemented with 3.0 mg litre IBA. Reducing the period of exposure to auxin to 7 days by transferring microshoots to auxin-free medium increased the frequency of root formation (84%), led to more rapid root formation and a reduction in basal callus formation.     

Histochemical studies of oxidoreductases, acid carbohydrates and glycoproteins in the epidermis of the electric eel Electrophorus electricus

The activities of various oxidative enzymes and the presence of acid carbohydrates and acid glycoproteins in the epithelial cells and the mucous goblet cells of the epidermis of the Teleost Electrophorus electricus have been determined by means of a series of selected histochemical techniques of light microscopy. The enzyme activities show a distribution pattern confined mainly to basal cell layers and outer cell layers with a comparatively lower gradient in the transitional cell layers. A mixture of sialic acids of both N-acylated and O-acylated types is found in the mucous goblet cells and the functional significance of mucous production is related to the first line of defense against pathogenic colonization. The higher incidence of various oxidoreductases distributed throughout the entire epidermis is correlated with their key role which can play in the processes of cell differentiation and cell multiplication except for those regarding keratin formation which is not produced in the epidermis of most fish.     

Reversible inhibition of cell multiplication in vitro by inhibitors of arginine esteroproteases

Two classes of active-site specific inhibitors of trypsin-like proteases have been shown to inhibit reversibly the multiplication of eukaryotic cells in vitro. The competitive inhibitors p-aminobenzamidine and benzamidine were found to arrest the growth of normal and transformed mouse fibroblasts and human KB cells. The inhibition of cell multiplication occurred within 24 h and was accompanied by substantial decreases in the rates of DNA and protein synthesis. The rate of RNA synthesis was relatively unaffected by the protease inhibitors. In agreement with the known inhibition constants (K_i) for their action against trypsin, p-aminobenzamidine was a much more effective inhibitor of cell multiplication than benzamidine. In addition, tosyllysine chloromethyl ketone (Tos-LysCH₂Cl), an active-site titrant and irreversible inhibitor of trypsin, was found to cause a reversible inhibition of growth. These results suggest that an essential protease activity is necessary for cell multiplication. However, in the case of mouse L-cells, all of the inhibitors and particulary p-aminobenzamidine caused excessive accumulation of lactate in the extracellular medium. This observation, which suggests the possibility of additional sites of action of these compounds in cells, was found to depend upon the cell type and appears to be unrelated to the inhibition of growth.     

Tetrahymena Thermophila: Growth In Synthetic Nutrient Medium In the Presence and Absence of Glucose

ABSTRACT This report contains the newest directions for preparation of the synthetic nutrient medium for some Tetrahymena species that do not require lipids. In the standard medium T. thermophila. strains SB 210 and 281, multiply at 37°C with doubling times of around 2 h and at 26°C around 5 h. We have established multiplication rates as functions of variations in the composition of the medium. In media in which all components are present at one-third of the normal concentrations and only the essential amino acids are included, growth and multiplication become sharply dependent on glucose in strain SB 281. Such media may be used for selection and enrichment of certain specified cell lines.     

Hypothetical way of pollen aperture patterning. 2. Formation of polycolpate patterns and pseudoaperture geometry

Deviant forms of polycolpate pollen, differing from the typical pattern in the number and arrangement of apertures, are found to be similar in distantly related dicotyledon taxa. The range of variation of common and deviant aperture patterns may be arranged as a continuous series, which may be described as a gradual and geometrically regular transformation of the deviant form with a meridional circular colpus to one of the common polycolpate conditions. Similar series have been observed in the taxa with colporate and pseudocolpate pollen. All possible spatial isomers and their mirror symmetrical variants of the deviant polycolpate and polypseudocolpate pollen have been predicted in terms of the suggested regularities of aperture multiplication. Some of them have been identified in the samples studied.     

Streptococcus pneumoniae multiplication in the allantoic cavity of developing chick embryos

The possibility of the active multiplication of S. pneumoniae (serotypes 1, 3, 6 and 19) in the allantoic cavity of chick embryos has been demonstrated. This multiplication is accompanied by the development of characteristic changes whose intensity and time of manifestation have been found to depend on the infective dose and the age of the embryo. The accumulation of S. pneumoniae in the allantoic cavity of chick embryos in the absence of visible changes in the biological properties of the infective agent after 5 successive subcultures makes it possible to recommend chick embryos as a model for the study of experimental pneumococcal infection.     

Compartmentalization of self-reproducing machineries: Multiplication of microsystems with self-instructing polymerization of amino acids

A theoretical model is presented for the self-instructing polymerization of free amino acids which proceeds inside microsystems which are phase-separated from the solution of thermal polyamino acids. It is shown theoretically that a compartmentalized microsystem fixes inside itself only the process with a faster macromolecular multiplication as time passes, even if the catalytic polymerization alone could spontaneously decrease the corresponding reaction rate. The compartmentalized machinery of macromolecular multiplication cannot reach its stationary state. The machinery is inevitably multiplied and alternates with those with either faster rates of macromolecular multiplication or slower rates of macromolecular degradation during their time development. These results are based upon the dynamic process that any material system acts by itself so as to remove any flow disequilibrium, that is, to maintain the continuity of material flow.