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The neural cell adhesion molecule N-CAM has been proposed to function in the guidance of outgrowing axons in the peripheral and central nervous system. Light microscopic observations have shown that the embryonic form of N-CAM (200-230 kDa) is present in the ventralmost part of the dorsal funiculus during corticospinal tract (CST) ingrowth in the first postnatal week (Joosten, Dev. Brain Res., 78 (1994) 226-236). Here, the subcellular localization of the embryonic form of N-CAM (E-NCAM) is determined by pre-embedding staining on vibratome sections and by postembedding immunogold-labelling on Epon embedded spinal cord sections. The electron microscopical observations indicate that E-NCAM is present on the outer membrane of CST growth cones as well as other unmyelinated axons which are present in the ventralmost part of the dorsal funiculus. Furthermore, E-NCAM is localized in an irregular patchy way on the outer side of the axonal membrane of small unmyelinated, later arriving CST axons. From these results it may be deduced that E-NCAM is involved in CST tract formation through guidance of outgrowing pioneer CST growth cones along other unmyelinated axons and through mediation of axon fasciculation of later arriving CST axons.

The hemagglutinating activity of 77 Klebsiella strains from the international collection, grown in a culture medium prepared on the basis of soy-bean flour enzymatic hydrolysate, was studied. These strains could be divided into four groups according to their capacity for synthesizing different types of hemagglutinins on their surface: 2 strains carried mannose-sensitive hemagglutinins, 18 strains had mannose-resistant K-type hemagglutinins, 48 strains exhibited the signs indicating the presence of both mannose-sensitive and mannose-resistant hemagglutinins, and 9 strains showed no hemagglutinating activity. The hemagglutinating activity of strains K-74, K-79, K-80, K-81 and K-82 was characterized. Of the reference strains under study, 22 strains were found to have mannose-resistant hemagglutinating activity with respect to fresh chick red blood cells. The occurrence of hemagglutinins in Klebsiella was shown to depend on the temperature of cultivation and the consistency of the culture medium. The formation of large-sized capsules in Klebsiella grown in the Werfel-Fergusson medium with a considerable content of saccharose was shown to cause the absorption of their fimbrial structures by the capsular substance and, as a consequence, the suppression of their hemagglutinating activity.

In the technology of the cultivation of K. pneumoniae vaccine strain 204 with a view to obtaining biomass for the production of antigenic preparations the traditionally used culture medium with full nutritional value has been replaced by the alternative variant of synthetic medium. The specific physiological and morphological features of this strain grown in synthetic culture medium have been studied and described. Irrespective of the composition of the culture media used for cultivation, the antigenic preparations have been shown to have no difference in their chemical composition, immunogenic and toxic properties.

The formation of the rutheniophilic microcapsule was studied in 5 meningococcal strains, group B, in accordance with the data of transmission electron microscopy. The microcapsular group-specific meningococcal polysaccharide was shown to enter into a specific osmiophilic reaction with ruthenium red. The study revealed that the formation of the microcapsule was practically independent of the concentration of serum, ferric chloride and amino-nitrogen in the medium in the ranges used in the experiments (0-20%, 0-32 mg/l and 49-160 mg% respectively). As noted in this study, the presence of serum in the medium led to the formation of the pseudocapsule on the surface of meningococci. The intensity of the formation of the microcapsule was shown to depend on the phenotypical properties of definite strains, on the phase of bacterial growth (it reached its maximum values at the exponential phase), as well as on the concentration of glucose in the medium.

The study of the ultrastructure of meningococci (strain C0638) in the process of submerged batch cultivation permitted the authors to follow changes in the fine structure of these microorganisms in different phases of the growth of the culture. Thus, the meningococcal populations retained their ultrastructure most intact during the exponential phase and the growth rate deceleration phase. During these growth phases a faintly pronounced reaction of the surface structures with ruthenium red was observed. In the stationary phase and in the atrophy phase this reaction was completely absent. The accumulation of exotoxin bubbles in the membrane was shown to achieve its maximum in the atrophy phase; besides, these structures regularly appeared at the death of the cells under the action of alkali. A hypothesis explaining the appearance of these bubbles is put forward.

Both surface and intracytoplasmic vesiculae have been shown to appear in meningococcal cells, strains 132, 125, and 133 belonging, respectively, to serogroups A, B, and C, in the process of batch cultivation. The surface microvesiculae are formed from the outer membrane of the cell wall during the whole process of batch cultivation. The intracytoplasmic membrane structures are formed in the process of cell autolysis. As revealed in this investigation, the strains under study, irrespective of their serogroup, are characterized by similar mechanisms of the formation of microvesiculae. The surface microvesiculae have been found to fall into three main types: monolamellar, multilamellar, and large spheroid bodies. The presence of specific functional features in each type of surface microvesiculae is suggested, as these microvesiculae, besides having their characteristic ultrastructure, differ in their contents. The attenuated culture of meningococcal strain 133, whose cells are notable among other strains under study for their more active (quantitatively) formation of microvesiculae, has been shown to have the highest toxicity for rabbits.

Nonencapsulated strains obtained by subculturing Streptococcus pneumoniae in a medium containing 0.5% of bile have been shown to possess a number of morphological and cultural features. The preparations obtained from the biomass of these strains by sonication have been found to possess antigenic, immunogenic and protective properties and to be specific to S. pneumoniae. The data obtained in this investigation may be considered indicative of the necessity for further study of these preparations with a view to their use for the analysis of serum samples taken from patients with bronchopulmonary diseases by means of enzyme immunoassay.

A comparative electron-microscopic study of Sh. flexneri 8512, Str. Dick Ia and Cor. pseudodiphthericum test strains, grown in experimental culture media prepared from inedible raw materials and in currently used culture media based on fish and meat, has been carried out. The ultrastructure of the test strains grown in culture media prepared from inedible raw materials has been shown to remain unchanged.