On the interaction of growth retardants with IAA and kinetin

In the pea test a highly positive response to the treatment with IAA reversed to a negative one or became 5 to 6 times weaker when CCC was applied together with IAA. In cultivating pea seedlings, following their decapitation, for two days in a 0.25 per cent CCC solution and then in water, growth of their cotyledonous axillaries (cotylaries) were inhibited. This inhibitive action of CCC could be made ineffective when the seedlings, following two-days’ cultivation in the CCC solution, were grown further in kinetin solutions (0.37–3 mg per 1). Cotylaries of decapitated pea seedlings, when grown in kinetin solutions were inhibited. With kinetin solutions of 6–12 mg/l a strong inhibition also occured in the growth of roots at the apical parts of which spherical swellings were developing. The CCC supplied to the roots of intact etiolated pea seedlings is translocated acropetally into the stem at a rate of about 5 cm per hour. Decapitation of the plant causes retardation of this transport, yet a coat of 0.00001–1% IAA or kinetin paste produces acceleration of the stream. Existence of an antagonism between CCC and IAA, demonstrated earlier, was found holding true also for B-9 (N, N-dimethyl-aminesuccinamic acid) and IAA, as the inhibitive action of B-9, 0.06% solution on the growth of lettuce hypocotyls was reduced to a highly significant degree when the plants were supplied with B-9 together with IAA at a concentration of 10 mg/l.     

Influence of exogenous DNA on Ypenyl-treated chromosomes ofVicia faba L.

This paper is a study of the effect of exogenous DNA of different genetic origins on the repair of meristematic cells of primary roots ofVicia faba, damaged by 24 hour treatment with 0·01mm solution of Ypenyl. Both kinds of DNA,i.e. isologous and heterologous, stimulated cell proliferation which was decreased by the action of the radiomimetic and influenced both dynamics of production of chromosome aberrations and the interchromosomal distribution of induced damage. While heterologous DNA increased the frequency of aberrations after all recovery periods studied, isologous DNA significantly decreased the number of chromosomal aberrations. Heterologous DNA increased at the same time the relative number of breaks in the group of small chromosomes, while by the action of isologous DNA the number of aberrations related to this group of chromosomes was relatively decreased.     

Serological analysis of eleven strains ofRhizobium japonicum

The present communication reports a serological analysis of eleven strains ofRhizobium japonicum. The slow-diffusing thermostable antigens were found to be suitable for the basic differentiation of the somatic serogroups inRhizobium japonicum. One to three precipitation bands of the slow-diffusing thermostable antigens, one to two bands of the fast-diffusing thermostable antigens and one to three bands of the thermolabile antigens were detectable in the whole cell cultures ofR. japonicum by means of the immunodiffusion technique. Two basic somatic serogroups were differentiated on the basis of the slow-diffusing thermostable antigens. The thermolabile antigens were identical in most of the strains.The author is greatly indebted to Mrs. M. Kabelovà for technical assistance.This investigation forms part of a contribution prepared by the Czechoslovak National Committee for the International Biological Programme (Section PP: Production Processes).     

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 inactivation ofBacillus subtilis transforming DNA by mutagenic agents

The inactivation of three genetic markers inBacillus subtilis transforming DNA by UV rays, nitrous acid and hydroxylamine was studied. The inactivation of markers by UV and HNO₂ was marker specific, whereas the hydroxylamine inactivates the markers approximately to the same degree.     

Taxonomisch-chorologische Studie über die ArtLeucanthemum rotundifolium (W. K.) DC.

Die Arbeit befasst sich mit der Nomenklatur, Morphologie, Phytogeographie, Chorologie, Phytozönologie und Ökologie der ArtLeucanthemum rotundifolium (W. K.) DC. innerhalb ihres Gesamtareals. Auf Grund der Analyse aller untersuchten Faktoren werden die Endergebnisse vom taxonomischen Gesichtspunkte vorgelegt.L. rotundifolium wird mit der am nächsten verwandten ArtL. vulgare Lam. s. l. verglichen.     

Die wirkung der β-(3-Pyridyl)-propion-und der β-(3-Pyridyl)-acrylsäure auf die Atmung der Wurzeln vonSinapis alba L.

V práci byly studovány rozdíly v ú?innosti kyseliny β-(3-pyridyl)-propionové (VIII) a β-(3-pyridyl)-akrylové (IX) v závislosti na stupni nenasycení pobo?ného ?etězce. Obě kyseliny inhibují r?st ko?ene i hypokotyluSinapis alba L. a zp?sobují inhibici sukcinátdehydrogenázového enzymového systému. Kyselina IX inhibuje zmíněný systém p?ibli?ně na dvojnásobek inhibice kyseliny VIII. Cytochromoxydázový systém z?stává témě? neovlivněn. Na základě experimen tálních výsledk? byla zp?esněna strukturní podmínka fytotoxické aktivity modelových slou?enin typu I v tom smyslu, ?e v?echny slou?eniny této struktury inhibují kromě r?stu také aktivitu sukcinátdehydrogenázového systému.     

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.     

Chromosome aberrations caused by the effect of ultrasound in the meristematic cells ofvicia faba

In our present work the formation of chromosome aberrations has been studied in dependence on the tima interval between sonication and fixation of the primary root tips of Vicia faba. Maximum occurrence of aberrations was recorded immediately after sonication. The results of our experiments pointed to the fact that the frequency of the induced changes was independent on the sonic waves intensity within the range of 0-2—3-0 W/cm² and on ultrasond treatment duration within the range of 1—20 min. Studies of the distribution of chromosome abnormalities caused by ultrasound between the large and small chromosomes of theVicia faba meristematic cells in various time intervals showed that the frequency of the aberrations in both chromosome groups was proportional to its total metaphase lengths. Analysis of the type of aberrations observed in various time intervals after sonication indicated the simultaneous formation of chromosome and chromatide abnormalities.