Organization and chemical composition of the cell wall of gramicidin S-producing Bacillus brevis

The morphology of cells and cell walls was studied in the Bacillus brevis G.-B. R form during its growth and gramicidin S accumulation in it. The membrane apparatus became more complicated and certain other morphological changes were detected in the cells with aging. The cell wall was rather complex even in young cells and consisted of three electron-dense layers where the external and internal layers had an ordered structure. Only the external layer underwent some modifications in the course of growth and these coincided in time with the beginning of intensive gramicidine S biosynthesis. However, the three-layer structure of the cell wall and the ordered organization of the external and internal layers remained unchanged. A preparation of cell walls and preparations of their external and internal layers were isolated from cells synthesizing gramicidine S in the amount of 20 micrograms/ml of the cultural broth. An acid protein having the molecular mass of 100 kD was shown to be the major component of the external layer according to the data of electrophoresis in PAAG with SDS. The middle layer was sensitive to lysozyme, did not have a ordered structure on electron micrographs, and consisted mainly of peptidoglycan.     

The hemispheric lateralization of the recognition of noisy visual stimuli in man

At tachistoscopic unilateral presentation of noisy visual stimuli and application of "yes-no" method in man predominance was found of the right hemisphere by the number and "yes" reaction time and of the left hemisphere by the number of responses "no". At verbal mnemic load preceding the presentation of visual patterns the left hemisphere asymmetry was observed by the number of "yes" responses and reactions time of both types. FMA was more clearly expressed in men in the first case and in women--in the second one. In more difficult conditions of recognition of several types of patterns, FMA was noticed mainly in women: initial left hemisphere advantage during the increase of the disturbance was changed to the right hemispheric one and appeared again. Preferential participation of the right hemisphere in singling out of the visual signal from noise is supposed. Possibility of the left hemispheric asymmetry manifestation was determined by the specificity and complexity of the visual task, by the level of the disturbance, presentation of competitive task and sexual composition of the group.     

Bilateral mechanisms of interference resistance in the striate cortex]

It has been shown that in animals with an intact corpus callosum the influence of photic interference is mainfested above all in EP depression. The degree of EP depression is directly dependent on the strength of the interference and is in inverse relationship with the strength of the determined stimulus. Against the background of a weak interference an other effect is possible in some cases, i.e. facilitation of the EP. These facts are interpreted as a result of postresponse subnormality of neurones and as excitation summation respectively. Section of the corpus callosum results in a weakening of the depressing effect of the photic interference on the EP appearing in response to a determined stimulus, and in an enhanced facilitating influence of weak photic interferences. A stronger influence of binocular photic interference as compared with the monocular one was observed in intact and callosotomized animals. A conclusion has been reached that the split brain has a stronger interference resistance as compared with the intact one.     

Hemisphere asymmetry of motor-feeding behavior of mice in a multi-alternative symmetrical maze

The behaviour of mice of BALB/c line was studied in a symmetrical multialternative Y-maze: their motor, alimentary and investigating activities as well as spatial-motor asymmetry. In animals with inactivated left hemisphere, as compared to intact ones, the motor and alimentary activities were lowered, and the investigating one augmented. Instead of the weak left-side asymmetry a distinct left-side preference appeared of most Y-maze sections, and right-side preference for approaches to the feeders. Elimination of the right hemisphere did not change the motor activity; the alimentary one decreased and the investigating one augmented, but less than during inactivation of the left hemisphere. On the whole, the right-side asymmetry appeared for all sections. According to all parameters studied, the influence of the left hemisphere on animal behaviour was more expressive and diverse. Spatial preference is formed with participation of influences of both hemispheres. The differences between them are more qualitative than quantitative.     

Interaction between structure of plant steroids and their effect on phytonematodes

The effects of certain plant steroids of the groups of furostanol glycosides, glycoalkaloids, and alpha-ecdysone on growth and development of phytoparasitic nematodes were studied. It was shown using an experimental system including tomato, Lycopersicon esculentum Mill., and root-knot nematode, Meloidogyne incognita Kofoid et White, that steroid molecule had significant nematicidic activity if it contained a carbohydrate moiety and an additional heterocycle in the steroid core. The maximum nematicidic activity is inherent in glycosides containing chacotriose as the carbohydrate moiety of the molecule. Some compounds tested in this work could be used for protecting plants against phytoparasitic nematodes.