Effects of the new antifungal antibiotic mucidin

The antibiotic activity of the antifungal substance mucidin was compared with the activity of nystatin and pimaricin. The antibiotics were tested by the plate method using 19 fungal species, mainly phytopathogenic ones. Toward 14 species, mucidin was ten times more active than nystatin and pimaricin, toward 5 species the activities were roughly the same. The antibiotics differed also in the sharpness of the inhibition zone boundaries.     

The passive anaphylactic reaction in guinea pigs elicited by whole and cathepsin D-degraded antigen

The systemic anaphylactic reaction and thein vitro anaphylactic contraction of the terminal segment of the ileum performed according to the Schultz-Dale technique, were elicited in guinea pigs passively sensitized with rabbit antibodies to human serum albumin, using whole and cathepsin D degraded antigen. The intensity of the systemic anaphylactic response that was evoked by degraded antigen was lower; a highly significant suppression of the response was obtained provided an antigen degraded more than by 70% was injected. With an increasing degradation of antigen, more animals responded with lower or even with no reaction; the number of animals developing severe or lethal shock, decreased at the same time. The number of animals that developed a medium anaphylactic response remained at the same level. The degraded antigen did not evoke the anaphylactic contraction of the terminal segment of the ileumin vitro, and moreover, it blocked the contraction after addition of the whole antigen.     

Regression analysis of the spontaneous spike activity of neurons in snail ganglia

Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group.     

On the media improving freeze-sectioning of plant material

Using a semiconductor freezing microtome, there is no difficulty in getting an ample supply of quite suitable sections of Ca formol fixed root tips ofVicia faba, applying Holt’s sirup or plain 0.88 M sucrose as media for keeping the material, getting the sections and treating them after sectioning, but the protoplasts shrink and often fall out from the cells. No improvement in this respect was revealed using — at different concentrations — sucrose and arabic gum alone. The changes in the proportions of the ingredients of the sirup were also ineffective. A series of experiments were therefore performed with plain sucrose, but none of the factors tested was efficient enough to improve the results as compared with the standard procedure, the gradual transfer being the only exception. Since this makes the procedure more laborious and time consuming, certain other media were tested, 0.88 M ethanol and 0.88 M dimethylsulf-oxide yielding the best results. Attempts are being made to understand some points of the present experience in connection with the results of other authors and on the basis of general theory respectively.     

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.