The penetration of Sporozoa into host cells]

The analysis of morphological and functional peculiarities of sporo- and merozoites as disseminative stages of the sporozoan life-cycle is given. Penetration of parasites into the host's cells is a complex multistepped process very similar to the induced but not completed phagocytosis. As a result of that process the formation of the integrated cell system, which consists of the host's cell and the unicellular parasite takes place.     

The evolutionary expansion of the Sporozoa

The sporozoans comprise a coherent group of protozoans, with characteristic and complex life cycles, containing 4–5000 species parasitic in invertebrates, particularly annelids and arthropods, and vertebrates. The group is a very successful one but neither its origins nor evolution are well understood. Considerations of traditional life cycles combined with newer molecular methodologies have thrown some light on the evolutionary expansions of the main groups of sporozoans, the gregarines, coccidia, haemosporidians and piroplasms. The sporozoans of economic importance such as the coccidia, malaria parasites and piroplasms have received most attention but the data obtained have also thrown new light on the possible evolution of less well studied groups and it is concluded that conclusions based on simple comparisons of life cycles will have to be modified. It is also clear that humans have played a major part in affecting the distribution and present abundance of many sporozoans of economic significance and probably also those of less importance, and that the rates of evolutionary expansion are much more rapid than previously thought.     

The origin of the arteria sigmoidea ima]

The authors report the results of their observations on the lowest sigmoid artery, carried out on 92 anatomical specimens coming from surgical operations on the sigmoid and rectum. The specimens were injected and radiographed immediately after their removal . The observations were often preceded by pre-operative angiographies performed for diagnostic reasons. The AA. document all the variational patterns of this artery. They confirm the poor functional value of this artery more known by the old surgeons than by the anatomists.     

The normal reaction of sinocarotidian origin in the rabbit]

Spontaneous changes of respiratory rate and blood pressure in the slightly anesthetized rabbit, contemporaneous with hippocampal synchronization, might be related with abrupt changes of the alertness. Registration of arousal reaction in hippocampal, thalamic and cortical leads, elicited by Hering nerve stimulation, shows that baro- and chemosensitive afferences may induce activation of areas which are usually involved in conditioning process.     

The adhesive properties of bacteria of intestinal origin]

Differences between strains of nonpathogenic Escherichia and lactobacilli, as well as some pathogenic bacteria of enteric origin (Escherichia, Shigella, Campylobacter), in their capacity to adhesion to rat enteric and colonic cells have been shown in vitro. The strains under study have been found to possess more pronounced adhesiveness with respect to colonic cells, which is indicative of their higher receptive capacity in comparison with enteric cells. In the absence of normal microflora lactobacilli and Escherichia exhibit increased adhesiveness with respect to enteric cells. Escherichia enterotoxigenic strains, Yersinia enterocolitica and Salmonella typhimurium virulent strains, Campylobacter jejuni clinical isolates possess more pronounced capacity for adhesion to enteric cells of Peyer's plaques than to other types of epithelial cells, which may be of importance in the pathogenesis of these infections.     

The origin and possible role of microvesicles in olfactory receptor cells]

Microvesicles and spherical particles have been described in the bulbs of receptor olfactory cells of Acipenser ruthenus. Two pathways of the origin of the above vesicles have been followed. These structures derive at the stage of differentiation from non-ciliary to ciliary cell type. The first of the pathways involves the autolysis of microfibril bundles produced during the regression of microvilli. The other one includes micropinocytosis induced on the basis of regressing microvilli. Taking into account the genesis of the microvesicles of the receptor cell bulb, it is concluded that they cannot contain a mediator able to modify membrane ion permeability in response to the specific stimulus of the odorant.     

The organization of purine and pyrimidine nucleotide biosynthesis in Sporozoa (Protozoa)]

Analysis of peculiarities in organization and functioning of metabolic ways of biosynthesis of purine and pyrimidine nucleotides in representatives of Sporozoa type has shown that molecular aftereffects of adaptation to intracellular parasitism in unicellular eukaryotes consists in the increase in the level of molecular organization, loss of some metabolic path ways and some enzymes, origin of a new metabolic system, a host-parasite one. Functioning of this system is achieved due to developing by the parasite mechanisms that are similar to the host's ones.     

Use of biochemical indices in the classification of Sporozoa

The paper presents a survey of literary and author's own data on metabolism of nitric bases, nucleosides and orotic acid in Eimeria, Toxoplasma and Plasmodium. Experimental data on nucleotide content of DNA, fractional content of ribosome RNA, isofermental spectrum of a number of oxidation-reduction enzymes and immunochemical analysis of antigens in various groups of Sporozoa (Eimeria, Toxoplasma and Plasmodium) are given. A possible use of biochemical and immunochemical data for the taxonomy of Sporozoa is suggested.     

Alpha-glucosidase inhibitors of microbial origin]

The data on spreading of inhibitors of alpha-glucosidases with microbial origin are given. Physiochemical characteristics of acorbose--a known inhibitor of alpha-glucosidases--and new inhibitor isolated from Streptomyces sp. are given in detail.     

Evolutionary origin of cell organelles]

A review on the evolutionary origin of the energy-yielding eukaryotic organelles is presented. Current autogenetic (endogenous compartmentalization) schemes, as well as different variants of symbiogenesis, are critically envisaged. A new symbiogenetic scheme is put forth, according to which mitochondria and chloroplasts originated divergently from a primordial photosynthetic organelle; the latter was acquired by endosymbiosis of ancient cyanobacteria in the cells of protoeukaryotes.     

The types of virus-specific structures in cells of human origin producing oncornaviruses]

In the cell cytoplasm of human tissue cultures Detroit-6 and AO which produce B type oncorna-virus, two types of virus-specific structures were revealed. Structures of type I were aggregated fibrils of 3 and 6 nm diametre. Structures of type II were nucleoids of A-particles of 70-80 nm diametre. They were rather well separated from cell components by centrifugation sucrose density gradient and repeated centrifugation in the sucrose concentration gradient. Fibrils were found in the density regions of the equilibrium gradient of 1.26 and 1.19 g/cm3, whereas A-particles were detected in the sones of the density of 1.29 and 1.23-124 g/cm3. Their sedimentation coefficients in the sucrose concentration gradients were about 150S and 250S, respectively. From both structure types similar RNA classes were extracted sedimenting in 60S, 45S and 35S regions (sucrose concentration gradient). In addition, 20S RNA was found within the 150S structures. Both structures sa. However, hydridization degree of RNA isolated from both structures with DNA synthesized enzymatically on extracellular various (DNA I) and A-particles (DNA II) was different. With DNA-I, 50-80% of RNA isolated from the type I structures and less than 20% of RNA extracted from the type II structures were hybridized. At the same time, strictly opposite situation (50-80% of RNA II and 20% of RNA I) was observed for DNA-II. These data show lack of genetic connection between these types of cytoplasmic structures and possible role of type I structures in reproduction of oncorna-virus type B.     

Main anticancer substances of vegetable origin]

During the last thirty years, the systematic screening of thousands of vegetal extracts has led to the isolation of numerous antitumor agents which belong to various chemical series. This paper only deals with some of them which are either of current clinical use or under advanced clinical experimentation, e.g., ellipticine, homoharringtonine, camptothecine, acronycine and their derivatives. The origin, the biological activity and its mechanism, and the toxicity of each of these alkaloids are described. These examples highlight the interest of the Plant Kingdom as source of biologically active new structures and the importance of a good knowledge of the mechanism of the activity and toxicity of active components. This knowledge gives a rational basis to prepare compounds of increased activity or reduced toxicity and to use them at their best in therapeutic.     

Superficial origin of erythrocytic chalone in polycythemia in vitro]

It was shown in the culture of rat bone marrow cells in experimental polycythemia that the chalone activity of erythrocytic chalone considerably drops in the presence of phytohemagglutinin (PHA). The chalone inhibits the agglutinating activity of PHA with respect to bone marrow cells. Absorption of the chalone on the immobilized PHA leads to disappearance from it and of PAS-positive bands recorded electrophoretically and to a strong decrease in PAS-negative band intensity. Experiments with preliminary incubation of rat red cells before preparation of the chalone suggest that in the course of its preparation two polypeptides one of which is PAS-positive are released into the medium. It is suggested that the chalone includes superficial membrane proteins of red cells, possibly, in the form of a combination of PAS-positive and PAS-negative bands. Potential mechanisms of chalone release from the surface of cells and features of their action on the cells are discussed.