Occurrence of lysosomes and the differentiation of rat liver cells

Summary The occurrence of lysosomes has been investigated electron microscopically and cytochemically in cells of rat liver in the course of ontogenesis.It has been found that primary lysosomes occur during the whole period under investigation and that they originate from the Golgi complex. Some of them assume the appearance of multivesicular bodies. Acid phosphatase activity is lower at the prenatal stage than after the birth. The occurrence of secondary lysosomes proceeds in two stages. Secondary lysosomes appear in a high number at the beginning of differentiation of the liver diverticulum (10–12 day of embryonic life). On the subsequent days they are, with few exceptions, no more present. At the end of the embryonic period (starting with the 20th day) and especially after the birth, they progressively grow in number and move from the region of central cytoplasm peripherally towards the bile capillary.Differences in occurrence of secondary lysosomes are in connexion with reconstruction of the liver primordium at the beginning of liver development and with the change in metabolism of the liver cell after the birth.     

Transformation in Rhizobium japonicum

Summary The transformation of streptomycin resistance in Rhizobium japonicum was studied. The susceptible strain 211 was selected from sixty strains and one step mutant resistant to streptomycin in concentration 1 mg per 1 ml was used as the donor. The peak of the competence curve appeared at the ninth hour of growth; the frequency, when the homologous strain had been used was 0.01 p.c. The transformed resistance was of the same level as in the donor strain.This investigation forms part of a contribution prepared by the Czechoslovak National Committee for the International Biological Programme (Section PP: Production Processes).     

Mire communities of Reykjanes peninsula,SW. Iceland (Plant communities of reykjanes peninsula,part I.)

In Reykjanes peninsula, mainly in the valley of Krísuvík, in all 6 mire associations were found, belonging to the alliancesEriophorion Scheuchzeri andCaricion canescentis-fuscae. Floristic, ecological and physiognomical differeces between the two alliances are discussed. Most of the associations seem to be restricted in their distribution to Iceland.     

Chromosome counts of some Mongolian plants

The paper gives the chromosome numbers of 45 species from 72 Mongolian localities, belonging to the genera:Amygdalus, Asparagus, Astragalus, Cancrinia, Caragana, Chamaerhodos, Chelidonium, Chesneya, Dianthus, Hypecoum, Lathyrus, Lilium, Oxytropis, Papaver, Potentilla, Schizonepeta, Sibbaldia, Thermopsis, Trifolium, Trigonella, Vicia. Chromosome morphology of three species ofChamaerhodos and taxonomical remarks on some other species are added. A new combinationSibbaldia sericea (Grubov) Soják is proposed.     

Physiological properties of microbial population as a basis for graphical solution of multi-stage continuous cultivations

A proposal for a graphical solution of the design of a multi-stage continuous culture system is presented. The holding times in individual stages are derived from the reciprocal values of the growth rate and of the product formation rate and plotted against the cell and product concentrations. Characteristic changes of physiologically significant paramaters are then projected on these production curves. Dedicated to Academican Ivan Málek on the occasion of his 60th birthday     

Attempt at quantitative analysis of interindividual variability in stress response of leucocyte levels in mice from the viewpoint of control theory

Summary The authors studied the dependence between the ability of systems regulating the level of peripheral leucocytes to damp the fluctuations of this level, occurring under conditions of repeated stressing of the organism by non-specific stress factors (isolation, starvation, handling for blood withdrawal) and the tolerance of the organism to the action of ionizing radiation (summary exposure to X-rays leading to death at repeated irradiation). This regulatory ability was expressed with the aid of the slope (coefficientb) of regression between the leucocytary valuesx _i, fluctuating in time, and the subsequent differences _i ( _i =x _i+1–x _i ). The highest tolerance to lethal action of radiation is correlated to such a regulatory behaviour of the organism at which the time necessary for adaptation of the system is shortest. The authors point out the suitability of the employed regulatory characteristic for the quantitative study of adaptability and resistance of the organism and its relatedness to the damping ratio, used in the automatic control theory.     

Postnatal differentiation of the Golgi apparatus and the dendrites of Purkinje cells of the rat cerebellum

Summary The morphology of postnatal differentiation of the Golgi apparatus, the nucleus, the perikaryon, and the dendrites was studied in Purkinje cells of the rat cerebellum for 30 days after birth using histochemical, histological, and electron microscopic methods.The Golgi apparatus during differentiation undergoes morphological and positional changes. From the 1st to 7th postnatal day, the Golgi apparatus is found in a supranuclear position, and is connected with the axes of differentiating primary dendrites by beam-like processes. From days 8 to 11 this connection disappears, and most of the Golgi apparatus assumes a lateronuclear and infranuclear position. After the 11th or 12th day, the Golgi apparatus is found in perinuclear and peripheral cytoplasmic positions. The formation of granular endoplasmic reticulum occurs in the vicinity of the perinuclear Golgi apparatus. The differentiation of cell and nuclear forms requires approximately 20 days. The morphological changes of differentiation are discussed in relation to the participation of the Golgi apparatus in the differentiation of dendrites and in the formation of the granular endoplasmic reticulum.     

Phenotypic,genotypic and environmental correlations of quantitative characters in winter wheat

In the experiment with 18 winter varieties the genotypic, phenotypic and environmental correlations were estimated in all combinations between the pairs of 11 quantitative characters. Both yield of grain with its components and further characters were evaluated, of which flag leaf size and leaf angle of the last but one leaf are of importance for the utilization of light energy and consequently for receiving maximum rates of photosynthesis. In simple genotypic and phenotypic correlations their different stability with regard to mineral nutrition, eventually to the date of sowing was proved. In the discussion the limited signification of simple correlation for the statement of complicated processes in plants caused by multiplied associations of characters was pointed out. In the example of yield components of the plant at the application of 60 kg N per hectare it was shown that also further unknown variable factors might participate in the genotypic correlation. It may be concluded that the inclusion of them when constructing the selection indexes will give further foundations for handling yield as a breeding or genetic character, and for the causal analysis of yield formation in wheat.     

Electrophoretic investigation of proteins in different root zones ofvicia faba L.

The differentiation of tissues is closely connected with the proteosynthesis. One can therfore assume that tissues with different types of cell growth (meristematic or elongation growth) and with different degrees of differentiation are different in their protein composition. In order to compare the protein composition of different plant organs, the method of disc electrophoresis on a polyacrylamide gel has been used by some authors. As compared with other methods used up to now, e. g. isolating proteins on DEAE cellulose or in Sephadex, this method does not need so much material and its resolution ability seems to be higher. It is also quicker and enables the study of several samples simultaneously. Its disadvantage is that proteins can be identified mainly by means of Rf and their quantity, measured from the intensity of staining of individual fractions in the gel, which may be misleading due to different sorption capacity of different proteins (Fri?Fri?ová 1967). None the less, it is good for comparison of protein composition of individual parts of the plant body. Different methods have been used to compare protein composition of individual growth zones in roots.Barsky,Ivanov andPushakova (1965) used luminiscence microscopy and found that in maize roots it is not possible to find substantial differences by this method.Morgan andReith (1954) arrived at similar conclusions. On the other hand,Steward et al. (1965) andMorris (1966) found qualitative differences in protein composition of different parts of pea roots using acrylamide electrophoresis. The results of the last named authors show considerable discrepancies in details, due perhaps to a different method of extraction (buffer, pH, purifying method). We have used acrylamide gel electrophoresis for investigating proteins in precisely defined growth zones of theVicia faba root.     

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.