The biosynthesis of levansucrase by Gluconobacter oxydans was shown to be induced in media containing sorbitol or fructose. An addition of glucose at a concentration of 0.1% to the culture growing in a medium with sorbitol stimulated the biosynthesis of levansucrase, whereas glucose at a concentration of 0.5-0.6% inhibited the enzyme synthesis by 20-30%. Gluconic acid, a product of glucose metabolism, also repressed the synthesis of levansucrase, but to a lesser degree than glucose. Cyclic adenosine-3',5-'monophosphate eliminated the repression by glucose added to a medium with sorbitol. An addition of chloramphenicol to the culture growing in a medium with sorbitol showed that the induction of levansucrase required de novo protein synthesis. The inhibiting action of chloramphenicol increased with its concentration. An increase in the concentration of actinomycin D from 5 to 200 micrograms/ml inhibited the bacterial growth by 50%, but stimulated the biosynthesis of levansucrase by 40%.

Administration of enzyme-inducing agents into newborn animals resulted in stable changes of the activities of the relevant inducible enzymes for long periods of their life in adulthood. The phenomenon designated as enzymic imprinting was used for correction of inherited enzymopathies in animals. Neonatal administration of galactose into the W/ssm rats with inherited galactosemia stably decreased galactose transport into the erythrocytes, increased activities of hexose oxidizing enzymes and prevented development of cataracts and other galactosemia symptoms. Neonatal administration of the inducer of mixed function oxidases into the SWR/J mice with inherited hypercholesterolemia stably increased the activities of these cholesterol oxidizing enzymes and abolished the hypercholesterolemia symptoms in adulthood. It is suggested that enzymic imprinting is due to amplification of genes coding the inducible enzymes on account of preferential copying of the induced mRNA's by reverse transcription. It is shown that the enzymic induction was accompanied by activation of RNA dependent DNA synthesis and the activity of this enzymatic system was distinctly higher in newborn animals.

It was recently shown in this laboratory that treatment of newborn animals with certain enzymic inducers causes stable changes in the activities of the inducible enzymes at a later adult stage. Cataracts, hepato-splenomegaly and other galactosemia symptoms in galactosemic W/SSM rats develop spontaneously. The increased uptake of galactose by erythrocytes, but not the decreased level of galactose-1-phosphate uridyl transferase (Gal-1-PUT) activity was assumed to be the major cause of the disease. The administration of galactose to the newborn W/SSM rats (2 mg/g of body weight for 14 days) resulted in a sustained decline in the uptake of 14C-galactose by erythrocytes at least for five months, in an increase of glucoso-6-phosphate dehydrogenase activity and in a continuous fall of Gal-1-PUT activity. The neonatal treatment of the galactosemic rats with galactose abolished the main symptoms of galactosemia (cararacts, hepato-splenomegally) in adult animals, perhaps ar a consequence of the stable changes in the galactose metabolism.

The enzyme apparatus involved in the catabolism of aromatic compounds in rhodococci is characterized by the presence of pyrocatechase and protocatechoate-3,4-dioxygenase as principal enzymes cleaving the aromatic cycle. Metapyrocatechase was found in about 30% of the rhodococci. All the enzymes are inducible. The inductor of pyrocatechase seems to be cyc-cys-muconate, and that of protocatechase appears to be 3-oxoadipate. The metapyrocatechase of rhodococci, in contrast to that of Pseudomonas, is not induced by benzoate, p-toluylate, p-xylene and phenol. The activity of metapyrocatechase rises 20-50 times comparing to the basal level only in the presence of p-cresol. The enzyme has a relatively low activity in rhodococci (50-200 nmole per 1 min per 1 mg of protein), though a very high affinity for methylcatechols. The activity of metapyrocatechase with methylcatechols is 2-5 times as high as that with catechol as a substrate, whereas the activity of pyrocatechase with methylcatechols is two times as low as that with catechol as a substrate. Such additional substrates as acetate, glycerol or fumarate have no effect on the qualitative composition of the key enzymes involved in the degradation of aromatic compounds in Rhodococcus carollinus 172. Glucose represses the synthesis of enzymes cleaving the aromatic ring by 100%. Fumarate taken in a 5-fold excess inhibits the activity of catechol oxygenases by 40%; if it is taken in a 1000-fold excess, it inhibits the enzyme activity by 100%.

The effect of mitomycin C and UV on spores before germination and two hours after it was investigated with Streptomyces narbonensis 2a producing beta-1,3/1,4-glucanglucan hydrolase (beta-glucanase). The lethal effect of mitomycin C on the germinating spores was considerably greater than that on the spores. The mutagenic activity of mitomycin C was closely related to the process of spore germination. The frequency of mutations was higher when mitomycin C acted on germinated spores. UV caused a lesser frequency of morphological mutations than mitomycin C did. The action of UV produced mutants which synthesized beta-glucanase of the exotype in the course of fermentation in a medium without an inductor.

Bacillus thuringiensis cells, depending on their physiological state, produce different quantities of exoprotease. Easily metabolizable carbon sources in the medium can affect the process in the opposite way: they inhibit synthesis of the enzyme by the cells in the exponential growth phase, and stimulate it by the sporulating cells. Apparently, cAMP is not an effector of catabolite repression regulating exoprotease synthesis by the cells in the exponential growth phase, inspite of stimulating the enzyme synthesis at the background of easily metabolizable carbon sources. The same effect is produced by cAMP in the absence of additional carbon sources. AMP, adenine, GMP and guanine exhibit a similar action on the enzyme synthesis; the effect is most pronounced in the medium without easily metabolizable carbon sources. The action of cGMP is specific: cGMP inhibits the synthesis of exoprotease in the presence of additional carbon sources, and stimulates it in the absence of easily metabolizable compounds.

Two new Djungarian hamster cell lines which are resistant to chloramphenicol (CAP) are described. The clonal DMCAP subline was obtained by incubation of HPRT-deficient DM-15 cells for 6 months in the medium containing 50 micron/ml of CAP. Resistance to CAP is determined in DMCAP cells by the cytoplasm: cytoplasts from these cells could transmit resistance to CAP into sensitive cells, such as L or DMCH-2/1 cells by hybridization. However, after transplantation of DMCAP nuclei into L cytoplasts, the resulting hybrid cells lost resistance to CAP to a great extent. Using the capacity of DMCAP cytoplasts to transfer CAP-resistance, we obtained a line of hybrids (cyt. DMCAP X DMCH-2/1) which was resistant to 8-azaguanine, CAP and colchicine. As in the original DMCH-2/1 cell line, colchicine-resistance in the cybrid line appeared to be associated with gene amplification. Thus, chromosomal analysis showed that the karyotype of the hybrids was identical to that of DMCH-2/1 cells. Both contained marker chromosomes with homogeneously staining regions (HSRs) and, during incubation in the colchicine-free medium, lost resistance to colchicine. The loss of resistance was accompanied by a decrease in the number of cells containing chromosomes with HSRs and an increase in the number with double minutes (DMs). Many cells containing small chromatin bodies in their cytoplasm also appeared. These chromatin bodies may be DMs lost from the nucleus during mitosis. These new sublines with cytoplasmic and nuclear genetic markers may be useful in the further study of cytoplasmic-nuclear interactions, particularly, in the analysis of possible activities of the DNA fragments which appear in the cytoplasm during reversion to colchicine sensitivity.

The effect of diphteria toxin on the synthesis and degradation of NAD+ and the hydrolysis of NADP+ in the nuclei of guinea pig kidney were studied. Treatment of animals with diphteria toxin (DT) results in considerable reduction of NADpyrophosphorylase activity, which starts 12 hours after incubation and is minimal (50% of that of the control animals) 18 hours after it. During this time interval DT does not affect the activity of NADase and decreases that of NADPase in the nuclei. Thus under diphterial intoxication a decrease of NADPase activity, the synthesis of NAD+ being reduced, probably provides for kidney cells more favourable conditions for maintenance of their synthetic reactions and for restoration of their normal metabolism. It was found that the non-ionic detergent Triton X-100 promotes the NADpyrophosphorylase activity in cell nuclei of intact animals by 40% (on the average) and does not affect the NAD+ synthesis in DT injected animals. Therefore DT not only reduces the nuclear NADpyrophosphorylase activity but also affects the nuclear envelope. The alteration of nuclei under DT treatment is suggested by the decrease of their histone content (30% on the average as compared with the control). The decrease of NADpyrophosphorylase activity under DT intoxication can be considered as an adaptive reaction limiting the availability of NAD+ as the substrate of the EF2 mono (ADP-ribosilation) which results in its unability to promote translation.

The absence of carbon, nitrogen and sulfur sources in the medium was shown to be a prerequisite for the production of exocellular proteases by Aspergillus candidus. The biosynthesis of proteases stops as soon as a limiting substrate is added to the medium. The rate of protease biosynthesis noticeably decreases if proline, alanine, glycine, valine, phenylalanine, serine, threonine, aspartic and glutamic acids are added, particularly during the first hours of incubation. Cysteine increases the delay in the onset of protease biosynthesis. Tryptophan, leucine, asparagine and glutamine considerable decrease the rate of exoprotease biosynthesis throughout the experiment. Arginine, histidine, lysine, ornithine and methionine added to the medium without a carbon source almost entirely inhibit the biosynthesis of exoproteases. A sulfur-deficient fungal mycelium synthesizes exoproteases at a high rate in the medium without a sulfur source whereas sulfate, methionine and cysteine suppress the process. Protein, being the only source of carbon, nitrogen or sulfur in the medium, abruptly decreases the rate of exoprotease biosynthesis.

The effect of phenobarbital on the luminescent system of Beneckea harveyi was studied. The inhibition of luminescence with phenobarbital was shown to be due to a disorder in the synthesis of an aldehyde factor, the endogenous substrate of bacterial luciferase. Upon the action of phenobarbital, the bacterium acquires the properties of "aldehyde" mutants, i. e. their luminescence is stimulated with exogenous decyl aldehyde. The luminescence of the cells was also stimulated with long-chain aldehydes, fatty acids and their analogues: apparently, the aldehyde factor is formed via incorporation of an oxygen atom into the terminal methyl of a saturated fatty acid or its analogue. Phenobarbital has no effect on the bacterial growth; however, it increases the content of luciferase in the culture. The results suggest that phenobarbital is not a direct inductor of luciferase synthesis. Possibly, the stimulating action of phenobarbital involves the inhibition of synthesis of the aldehyde factor and, consequently, an increase in the concentration of intermediate products of its synthesis.

The regulation of p-xylene methylhydroxylase, metapyrocatechase, pyrocatechase and protocatechoate-3,4-dioxygenase was studied in Pseudomonas aeruginosa 2x. Methylhydroxylase, the first enzyme of p-xylene oxidation, was shown to be synthesized in the strain in a constitutive manner and to be regulated at the level of the enzyme activity. Metapyrocatechase, protocatechase and pyrocatechase are inducible enzymes; these are repressed to a different extent by the end products of p-xylene oxidation. Metapyrocatechase has a broader substrate specificity as compared to pyrocatechase and is induced by a greater number of substrates, the affinity for different substrates depending on the structure of an inductor. Presumably, two isofunctional metapyrocatechases exist in P. aeruginosa 2 x.