Horizontal transfer of catabolic plasmids in the process of naphthalene biodegradation in model soil systems

The process of naphthalene degradation by indigenous, introduced, and transconjugant strains was studied in laboratory soil microcosms. Conjugation transfer of catabolic plasmids was demonstrated in naphthalene-contaminated soil. Both indigenous microorganisms and an introduced laboratory strain BS394 (pNF142::TnMod-OTc) served as donors of these plasmids. The indigenous bacterial degraders of naphthalene isolated from soil were identified as Pseudomonas putida and Pseudomonas fluorescens. The frequency of plasmid transfer in soil was 10(-5)-10(-4) per donor cell. The activity of the key enzymes of naphthalene biodegradation in indigenous and transconjugant strains was studied. Transconjugant strains harboring indigenous catabolic plasmids possessed high salicylate hydroxylase and low catechol-2,3-dioxygenase activities, in contrast to indigenous degraders, which had a high level of catechol-2,3-dioxygenase activity and a low level of salicylate hydroxylase. Naphthalene degradation in batch culture in liquid mineral medium was shown to accelerate due to cooperation of the indigenous naphthalene degrader P. fluorescens AP1 and the transconjugant strain P. putida KT2442 harboring the indigenous catabolic plasmid pAP35. The role of conjugative transfer of naphthalene biodegradation plasmids in acceleration of naphthalene degradation was demonstrated in laboratory soil microcosms.     

Membrane fluidity controls redox-regulated cold stress responses in cyanobacteria

Membrane fluidity is the important regulator of cellular responses to changing ambient temperature. Bacteria perceive cold by the transmembrane histidine kinases that sense changes in thickness of the cytoplasmic membrane due to its rigidification. In the cyanobacterium Synechocystis, about a half of cold-responsive genes is controlled by the light-dependent transmembrane histidine kinase Hik33, which also partially controls the responses to osmotic, salt, and oxidative stress. This implies the existence of some universal, but yet unknown signal that triggers adaptive gene expression in response to various stressors. Here we selectively probed the components of photosynthetic machinery and functionally characterized the thermodynamics of cyanobacterial photosynthetic membranes with genetically altered fluidity. We show that the rate of oxidation of the quinone pool (PQ), which interacts with both photosynthetic and respiratory electron transport chains, depends on membrane fluidity. Inhibitor-induced stimulation of redox changes in PQ triggers cold-induced gene expression. Thus, the fluidity-dependent changes in the redox state of PQ may universally trigger cellular responses to stressors that affect membrane properties.     

Rhythm of Protein Synthesis in Cultures of Hepatocytes from Rats of Different Ages. Norm and Effect of the Peptide Lyvagen

The circumhoralian rhythm of protein synthesis was determined in a monolayer culture of hepatocytes from rats at the age of 1 to 24 months and weighing from 45 to 480 g, respectively. The peptide lyvagen (Lys-Glu-Asp-Ala) obtained by directed chemical synthesis on the basis of amino acid analysis of the liver polypeptide preparations increased the level of protein synthesis in the hepatocytes from rats of different ages; the highest effect was observed in the cells of old animals. In old rats, lyvagen increased the amplitude of protein synthesis fluctuations. The peptide epitalon (Ala-Glu-Asp-Gly) constructed on the basis of analysis of the epiphysis peptides did not change the intensity of protein synthesis in the cultured hepatocytes.     

Extraembryonic motor activity during embryogenesis of higher vertebrates

Rhythmic motor activity of the extra-embryo structures as well as the embryo motor activity play a major part in normal development of higher vertebrates. When comparing birds and mammals, a trend towards complication of the motor activity regulation is observed. Reptiles as a class of the vertebrates have not been studied enough in this respect. Apart from the regular changes of extra-embryonic rhythmic motor activity, there are some changes in this activity depending on alterations of environmental factors (temperature, gas composition of air, etc.). The extra-embryonic rhythmic motor activity seems to take part in adaptation of the embryo to changing environmental conditions thus maintaining homeostasis of developing embryo.     

The possible connection of adenylic nucleotides to the rhythm of protein synthesis in hepatocytes in vitro

Circahoral protein synthesis rhythms observed in hepatocytes in vitro differ in phase from the oscillations of intracellular amount of ATP. ATP added to culture medium interferes with the rhythms of protein synthesis and intracellular DNA content. Addition of ADP increases both the incorporation level of hepatocytes and ATP content. The data obtained has been discussed.     

Isolation of new species of the genus Actinomadura on selective media with streptomycin and bruneomycin]

In the screening programme using selective media with streptomycin (25, 50 and 100 gamma/ml) and bruneomycin (0.5, 1 and 2 gamma/ml) 3 unusual actinomycetous cultures forming short, rarely long chains of straight, hook-like or spiral spores with 1 or rarely 2 turns were isolated. The study of the cell wall composition of the isolates showed that the walls contained meso-diaminopimelic acid and a sugar madurose. On the basis of the morphological structure and the cell wall composition the isolates were classified as belonging to Actinomadura. Comparison of the cultures with the Actinomadura species described in the literature showed that the isolates were new species of the genera, i. e. Am. coerulea sp. nov., Am. cremea sp. nov. and Am. salmonea sp. nov.     

Rate of benyzylpenicillin inactivation in native solutions during extraction]

The constants of benzylpenicillin inactivation in acidified fermentation broth filtrates were different in various filtrate batches. Marked inactivation of the antibiotic in the filtrates immediately after their acidification was observed. Possible losses of the antibiotic due to inactivation under conditions of extraction were estimated.     

Rhythm of protein concentration and incorporation of 3H-lysine into hepatocytes in vitro]

"In vitro" incubated slices of the rat liver, by the method of interferometry combined with radioautography, have demonstrated hour's rhythmic fluctuations in protein concentration and 3H-lysine incorporation into proteins. The biochemical method has demonstrated fluctuations in protein synthesis rate in the same cells with an average period of about one hour. The possibility to apply the interferometric method in combination with radioautography for revealing quantitative changes of protein in slices of organic cultures is demonstrated.     

Mechanism of plasmid ColEl and pMB-9 mobilization by plasmid F'lac+ in Escherichia coli K-12]

The genetic control and mechanism of mobilization of the non-conjugative plasmids ColE1 and pMB-9 by the conjugative plasmids was orived to be recA-independent process in contrast to the mobilization of the chromosomal marker pro. Acridine orange and ethidium bromide curing data together with the results of electrophoretic analysis of plasmid DNA suggest that the plasmids F' lac+ and pMB-9 as well as F' lac+ and ColE1 remain autonomous after their contransfer to recipient cells. These data argue in favour of non-recombinational nature of the plasmid mobilization process. The possibility of transmission of a non-conjugative plasmid without transmission of a conjugative one from the donor strain carrying both plasmids was established. The results obtained are discussed with respect to the hypothesis on the effect of diffusible products encoded by the conjugative plasmid and required of the mobilization of the non-conjugative plasmid.     

Effect of Temperature on the Rate of Oxygen Consumption during the Second Half of Embryonic and Early Postembryonic Development of European Pond Turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Oxygen consumption by eggs of European pond turtle was determined at two constant incubation temperatures of 25 and 28°C during the second half of embryogenesis. During development at both temperatures, the rate of oxygen consumption initially increased to remain constant during the last quarter of embryogenesis. The difference between the rates of oxygen consumption at these temperatures decreased during the studied period. The coefficient Q₁₀ for the rate of oxygen consumption decreased from 9 to 1.7. At an incubation temperature of 28°C, the changes in the rate of oxygen consumption in response to a short-term temperature decrease to 25°C or increase to 30°C depended on the developmental stage and were most pronounced at the beginning of the studied period. During late embryonic and first 2.5 months of postembryonic development, the rate of oxygen consumption did not significantly differ after such temperature changes. The regulatory mechanisms formed during embryonic development are proposed to maintain the level of oxygen consumption during temperature changes.