Effect of root tip amputation on spiral oscillations of the growing hypocotyl with radicle of the pea (Pisum sativum L.)

In order to interpret the mechanism of elongation growth of the hypocotyl with radicle in the first stages of germination of the pea seed (Pisum sativum L.) a cybernetic model utilizing feed-back as a mechanism of correcting the wrong direction of growth was proposed (Spurný 1966, 1967). In the present study, the effect of amputation of the root tip as the control centre on the trajectory of the growing radicle was investigated. The results have shown that the hypocotyl grows, elongates—the rate of growth being slightly lower than that of the standard, but that no spiral oscillations at all are executed by the organ after amputation of the root tip. This finding appears to confirm the applicability of the proposed cybernetic model, for amputation of the root tip means that not only the control block is eliminated, but also that the channel of feed-back impulses to zone of elongation is interrupted.     

Über den Bau der Wandungen des Aquaeductus cerebri und des IV. Ventrikels der Katze

Zusammenfassung An Paraffinschnitten durch perfusionsfixierte Gehirne von erwachsenen Katzen werden in der Wand des Aquaeductus cerebri zwei von cranial nach caudal verlaufende Gliafaserbündel beschrieben, deren eines in das Velum medullare anterius einstrahlt, während das andere Anschluß an ein Faserbündel gewinnt, welches in der Seitenwand des IV. Ventrikels verläuft. — Es wird gezeigt, daß im Boden des IV. Ventrikels am Eingang in den Recessus lateralis sowie im Boden des gesamten Recessus lateralis unmittelbar unter dem Ependym einzeln gelegene Nervenzellen vorkommen. Diese bisher unbekannten Zellen werden als ein flächenhaft ausgebreitetes Kerngebiet mit enger Beziehung zum Ventrikelsystem angesehen.

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On the structure of the walls of the aquaeductus mesencephali and of the IV^th ventricle of the cat

Summary In paraffin sections through the brains of adult cats two thick bundles of glia fibres are shown to be running in the cranio-caudal direction within the wall of the aqueductus cerebri. One of the bundles enters the velum medullare anterius whereas the other is continuous with a bundle of glia fibres that runs within the lateral wall of the IVth cerebral ventricle. — In the floor of the IVth ventricle near the entrance to the lateral recess and in the floor of the entire lateral recess nerve cells are shown to occur immediately underneath the ependyma. These cells, which so far have not been described, are thought to constitute an extremely thin nucleus having a special relationship to the ventricular system.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Ultrastructure of the surface of multiple scars inSaccharomycodes ludwigii

The use of induced primuline fluorescence led to the discovery of a new type of yeast scars (multiple scars) in the generaKloeckera, Saccharomycodes, Nadsonia andHanseniaspora. The structure and ultrastructure of their surface was studied by electron microscopy, using carbon replicas and isolated cell walls.     

Ribosomes in growing and non-growing bacterial cells

1. 1.
   It was found that growing cells always contained more different groups of ribosomes and their total amount was greater than in non-growing cells or spores, in which only two ribosome groups with different sedimentation constants, according to the species of microorganism, were consistently found.     

Changes in the radioresistance of bacteria after the inhibition of proteosynthesis in the preirradiation phase

The strain ofEscherichia coli WP₂ (try_v) was irradiated with UV light, at a dosage of 240 erg/mm. Proteosynthesis was inhibited by the elimination of the essential amino acid from the cultivation medium. Changes in radioresistance were followed during 45 minutes of starvation and during the subsequent 45 minutes of restitution after the addition of the essential amino acid. The radioresistance of the cells showed a linear increase immediately after the removal of the essential amino acids, proportional to the duration of the inhibition of proteosynthesis. The increase in radioresistance was shown to be reversible. After the addition of the essential amino acid there was an immediate decrease in radioresistance which was most marked in the first 15 minutes.     

Amylase heterogeneity variants in man

The existence of six amylase heterogeneity variants in serum and urine has been discovered in a group of 111 families with twins, and the frequence of each variant was determined. It had been shown that each of these amylase heterogeneity variants is inherited codominantly, and the mode of inheritance is demonstrated schematically.These amylase heterogeneity variants may be used as an aid to twin zygosity determination and also in paternity problems.     

Contribution to the structural characterization of gamma globulin from pig colostrum

From the results obtained in the present work it is concluded that gamma globulin of the 7 S type (γG) which represents the main immunoglobulin component of pig colostrum, differs from serum γG globulin by the presence of another type of polypeptide chain, designed L₂; the latter was detected after S-sulfonation in starch gel electrophoresis as the fastest moving component and its immunoelectrophoretic pattern shows the presence of two precipitating components. Preparation of soluble heavy and light chains enabled us to study them imunochemically. The heavy chain is represented by two zones; the fainter one was not detected in comparative analysis of the heavy chain of serum γG globulin. The L₁ chain of colostral gamma globulin and the light chain of serum gamma globulin seem to contain three precipitating components, one of which appears due to aging of the chain solution in the presence of glycine. The material from colostrum seems to contain a larger amount of this component than serum. Further it was shown that the component arising in this way is antigenically closely related to the heavy chain.     

Study of the growth and development ofChlorella populations in the culture as a whole

Colour tests for study of the nuclear apparatus ofChlorella cells are described. It can be concluded from the results thatChlorella cell nucleus contains a relatively large nucleolus; the peripheral layers of the nucleus are rich in chromatin only in the nuclear division phase. The nucleus divides by a simplified form of mitosis, characterized morphologically by simple constriction.     

Changes in the biological activity of agropyrene on combined application with humus substances in the cultivation ofScenedesmus obliquus (TURP.) krüger

The work is concerned with the question of the effect of humic acids on the biological action of agropyrene, the effective substance from the rootstock of Agropyron repens (L.) P. BEAUV. The test organism was the alga Scenedesmus obliquus (TURP.) KRÜGER, cultivated in mineral solution. The basic biological test was the determination of the number and size of the cells of this alga. It was found that the way in which agropyrene acts on combined application with humus acids depends on which humus fraction is used. It can display a synergic action if humic acid is used, since this substance probably facilitates the penetration of agropyrene into the cells. On the other hand, fulvic acid counteracts the activity of agropyrene and this most probably by mutual binding and blocking of active groups and links.