Progesterone transformations as a diagnostic feature in the generaAlternaria,Stemphylium andCladosporium

Various species of the generaAlternaria, Stemphylium andCladosporium were shown to display a specific reaction characteristic for the given genus. In theAlternaria genus this is a 1-2-dehydrogenation of the A ring of the steroid molecule, inStemphylium 14α-hydroxylation and inCladosporium 7β-hydroxylation. This chemotaxonomic feature may supplement morphological and functional criteria in the taxonomy of filamentous fungi (Hyphomycetes).     

Further observations on the effect of ethionine on the synthesis of β-galactosidase inEscherichia coli: Formation of an immunologically cross-reacting protein

It was found that ethionine partially inhibits the transport of the inducer (TMG) of β-galactosidase into the cells ofEscherichia coli ML-30. The synthesis of β-galactosidase-specific messenger RNA is not inhibited. Ethionine appears to be incorporated into proteins synthesized by the strains used. The incorporation of ethionine into the molecule of β-galactosidase results in the synthesis of an enzymically inactive, immunologically cross-reacting protein.     

Antibacterially active substances

Synthesis of two hydroxy-derivatives of nalidixic acid as a result of microbial transformation was demonstrated in certain species of the genusAspergillus. Aspergillus alliaceus produced 7-hydroxy-nalidixic acid andAspergillus niger 6-hydroxy-nalidixic acid. It was demonstrated that the antibacterial activity of both hydroxy-derivatives (tested inEscherichia coli) was lower than that of the initial nalidixis acid.     

The effect of nucleosides on the induced synthesis of β-galactosidase in non-growing cells ofEscherichia coli

The induced synthesis of β-galactosidase in non-growing cells ofEscherichia coli starving for exogenous carbon and nitrogen sources was stimulated markedly by the addition of any of four nucleosides tested: adenosine, guanosine, cytidine, and uridine. Adenosine was used as a representative of this group of compounds in most experiments. The decrease of ability of the cells to synthesize β-galactosidase, resulting from a prolonged starvation for exogenous carbon and nitrogen, was removed by adenosine. This compound also considerably reduced the inhibitory effect of metabolic poisons on the induced synthesis of β-galactosidase. The blockade of induced β-galactosidase synthesis evoked in aerobically grown cells by anaerobic starvation for exogenous sources of carbon and nitrogen was also significantly reduced by adenosine. The weak transient catabolic repression of induced synthesis of β-galactosidase evoked by glucose in non-growing cells ofEscherichia coli deprived of exogenous carbon and nitrogen sources was prevented by adenosine. The total repression caused by higher glucose concentrations was not influenced by this compound. The results are discussed from the point of view of the role of the energy state ofEscherichia coli cells in the regulation of β-galactosidase synthesis.     

Effect of trophic conditions on aspartate transamination in wheat plants

The enzymatic transamination reactions between aspartic and α-ketoglutaric acid and between aspartic and pyruvic acid were studied in fresh dialysed extracts of young wheat plants cultivated under various trophical conditions, in mineral solution (Knop), in the solution of an soil organic substance (potassium humate) and without nutrients (H₂O). Simultaneously, the level of endogenic aspartic acid, glutamic acid and the growth values were determined. The enzymatic reactions were characterized by determining the optimum pH, the time course, and the effect of coenzyme and of inhibitors. The activity of the aspartate-glutamate transaminase from the root system of plants was considerably higher than the activity of the overground organs. The enzymatic activity from both parts of the plant was inversely proportional to the growth rate: intensive growth of the plants from the Knop variant was connected with their low enzymatic activity; the level of endogenic glutamic acid was high. The slow growth of the plants without nutrients was connected with a higher enzymatic activity; the level of endogenic glutamic acid was low. The plants from the potassium humate variant had an intermediate position between these two variants from the point of view of growth as well as from that of enzymatic activity. The plants with insufficient nutrition (slow growth, low level of endogenic glutamic acid) apparently have a low capacity for supplementing the glutamic acid deficit, which is essential for the metabolic processes, by increasing the activity of the reactions leading to glutamic acid synthesis (Asp-Glu) and, on the other hand, by decreasing the reactions utilizing it (Glu-Ala). For wheat plants the active aspartate-glutamate reaction is obviously physiologically more important than the direct reaction glutamate-aspartate and the reaction aspartate-alanine which in all cases had a very low activity.     

Peroxidases of different parts of the pumpkin plant (Cucurbita pepo L.)

We compared the occurrence of peroxidase isozymes in protein extract from roots, hypocotyls and cotyledons of 10 dayCucurbita pepo plants and of adult leaves of older plants by means of starch gel and polyacryl amide gel electrophoresis. We reached maximum discrimination by means of starch gel electrophoresis: 11 zones were ascertained on the cathode side and about 2 on the anode side at pH 3.1. Two zones occurred regularly:A and (the latter having a more complicated structure). ZoneD is characteristic for roots, but is it suppressed and seldom found with leaves. On the other hand zonesC ₁ andC ₂ are clearly discernible with leaves but are substantially less evident with roots. The character of anodic zoneZ is discussed later in this paper.     

Effect of ethionine on the synthesis of β-galactosidase inEscherichia coli

Ethionine at concentrations of 10⁻³M, 5×10⁻³M and 10⁻²M inhibits growth, both of β-galactosidase inducible ML-30 and constitutive ML-308Escherichia coli strains. The protein synthesis (measured by the incorporation of l-leucine-¹⁴C and l-aspartic-¹⁴C acid into proteins) of these strains is inhibited to the same extent as their growth. The synthesis of inducible and constitutive β-galactosidase produced by the strains ML-30 and ML-308, respectively, is considerably inhibited by ethionine.     

Spores of microorganisms

6-Azauracil at a concentration of 1 μmole/ml inhibits by 50% the outgrowth of germinated spores of a strain ofBacillus cereus, concentration of 1.5 μmole/ml resulting in 100% inhibition. Two distinct maxima of sensitivity to 6-azauracil are observed during postgerminative development of spores. The first occurs during early stages of development (immediately after depolymerization period) and the second after about 60 min of cultivation (late stage of swelling). Uracil reverses the inhibition of the outgrowth of spores caused by 6-azauracil when added during 0–30 min of the spore development. The addition of uracil after 30 min of the germination does not bring about the reversion of the effect of 6-azauracil. An important role of pyrimidine pathway via orotidine 5′-phosphate in germinating spores was proved, suggesting a possible use of 6-azauracil in synchronization of the postgerminative development of spores.     

Increased sensitivity of the respiratory system of plants grown in gibberellic acid toward fluoride

V souvislosti s d?ívěj?imi údaji (Lu?tinec a Krektjle 1959, Lu?tinec, Krekule a PokornÁ 1960) o silném inhibi?ním ú?inku fluoridu na dychání rostlin pěstovaných v roztoku kyseliny giberelové byl pomocí specificky zna?ené glukosy a respira?ních inhibitor? zji?tován vztah krátko- i dlouhodobého p?sobení kyseliny giberelové k poměru mezi podíly glykolytického a pentosofosfátového odbourání v respiraci list? p?enice. V souhlase s výsledky Fanga a spol. (1960) byIo zji?těno, ?e kyselina giberelová v koncentracích 2 a? 80 mg/l neovlivńuje během několikahodinového p?sobení na roz?ezané listy p?enice poměr radioaktivit¹⁴CO₂ uvolněného z glukosy-6-¹⁴C a -1-¹⁴C (C₆/C₁) ani nemění v koncentraci 10 mg/l stupeń inhibice dýchání fluoridem, monojodacetátem a malonátem a spot?ebu kyslíku. Výdej¹⁴CO₂ z glukosy-l-¹⁴C a -6-¹⁴C kyselina giberelová sni?uje v lineární závislosti na pou?itých koncentracích. U rostlin pěstovaných v roztoku kyseliny giberelové (10–20 mg/l) se rychleji sni?uje poměr C₆C₁ i absolutní hodnoty radioaktivity během několika dní od vyklí?ení, ne? u rostlin pěstovaných ve vodě. To svěd?í o rychlej?ím zvět?ování podílu pentosového cyklu v respiraci pokusných rostlin. Fluorid brzdí p?i stejném nebo men?ím obsahu ve tkáni dýchání list? rostlin pěstovaných v roztoku kyseliny giberelové silněji ne? dýchání rostlin pěstovaných ve vodě, zatimco ûcinek monojodacetátu a malonátu je u stejně starých rostlin (4 dny) obou variant stejný. O mo?ných p?í?inách tohoto jevu bylo diskutováno.