[The ecological concept of parasitism]. / Ekologicheskaia kontseptsiia parazitizma.

Analysis of morpho-ecological adaptations of parasites showed that their necessary and sufficient characteristic is their inhabiting the host environment. Integration with the environment is achieved 1) by adaptations towards a particular habitat (first order environment) at certain phases of ontogenesis, and 2) by adaptations to the aggregate of hosts, their ecology and factors regulating the numbers of parasites (second order environment) at the level of their entire life cycle. The evolutionary progress of parasites is sustained by the increase in their independence from extrinsic factors not by means of general organization complication and integration (as in free-living animals), but by elimination of free-living developmental stages and by increase of integration with the host environment. The basis of the latter is formed by ecological adjusting of parasites to the environment. It is achieved by syncytial transformation of the covers and the use of communication means analogous to those of host cells. The consequence of host-parasite integration is the transition of parasites from resource consumption to the "management" of the environment. It is manifested by their influence on defensive reactions and other functions of the organism, as well as on its behavior and ecology. Parasitism may turn into other forms of coexistence (commensalism, mutualism) in the course of coevolution, as a result of dialectical overcoming of antagonistic interactions of the two partners.

[The secretory proteins in the plerocercoids of the cestode Digramma interrupta and their enzymatic activity]. / Sekretornye belki plerotserkoidov tsestody Digramma interrupta i ikh fermentativnaia aktivnost'.

A composition of secretory proteins of plerocercoids of the cestode Digramma interrupta and their enzyme activity have been studied. It has been shown that plerocercoids produce 26 secretory proteins with molecular weight range of 3.9 to 112.2 kDa. These secretory polypeptides possess protease, DNAase and RNAase activities.

[Changes in the monocercus cercomer in the cysticercoid cavity and the hemocoel of the nonspecific host]. / Izmeneniia tserkomera monotserkov v polosti tsistitserkoida i gemotsele nespetsificheskogo khoziana.

In order to elucidate the functional role of cercomer in larvae of the monocercus type their transplantation from the specific host Chironomus obtusidens to Gammarus lacustris was conducted. At early stages after the transplantation proceeds an increase in the functional activity of the tegument of follicles of the cercomer followed by their complete destruction in 3 or 4 days. On the surface of the exocyst membrane an adhesion of the host's haemocytes occurs, which becomes more distinct in 3-4 days when the process acquires a character of local encapsulation. Within the same period, in the places of haemocytes aggregation, a local resorption of the exocyst external membrane takes place. Later intensification of the host response to transplant is associated with the destruction of follicles of the cercomer. In one case the occurrence of follicles of the cercomer in the cavity of cysticercoid was observed that is caused by the microbe affection of the latter. In the zone of contact of the tegument of scolex and neck with follicles of the cercomer an increased secretion (the microapocrine type) of the tegument, disturbance of the microvillous tegument of the cercomer's follicles and their destruction are observed. Incompatibility of the tegument of definitive departments and cercomer, which arises during differentiation of larvae, is supposed to affect the formation of scolex invagination in the evolution of larvae of Hymenolepis.

[Structure and differentiation of the inner egg membrane of Trichocephaloides megalocephala (Cestoda, Dilepididae)]. / Struktura i differentsirovka vnutrenni obolochki iaits Trichocephaloides megalocephala (Cestoda, Dilepididae).

Electron microscope studies of the inner membrane of developing eggs of T. megalocephala were carried out. At early developmental stages the inner membrane is a syncytial cytoplasmatic layer lying on the basal plate of the embryo. At the preoncosphere stage the division of the membrane into two zones (external and internal ones) takes place. Initially the differentiation manifests itself in the cytoplasm polarisation; at the end of the middle preoncosphere stage the zones are divided by the "oncosphere membrane". The formation of the "oncosphere membrane" is accomplished by the external part of the internal zone. Embryophore is a derivative of the external zone, at the final stages of the formation the embryophore material is transformed from granular into thin-fibrillary. The origin of the external integument of oncospheres of cyclophillids, which, as it has been shown for T. megalocephala, is a derivative of the inner membrane rather than of specialized epithelial oncosphere cells, is considered.

[Cytomorphological characteristics of the tegument of daughter larvae in the cestode Taenia crassiceps]. / Tsitomorfologicheskie osobennosti tegumenta dochernykh lichinok tsestody Taenia crassiceps.

At the early stages of asexual breeding, the daughter larvae of T. crassicaps display destructive changes of the tegument due to its hyperfunction. The reparation of tegumental cytons is followed by the appearance of specific "brushes" of fibrillar material on the karyolemma of their nuclei. They are supposed to occur as a result of protein synthesis necessary for the reconstruction of cellular structures, mainly, of the nucleus. The abundant synthesized fibrillar falls into decay being transformed into bodies containing crystals which are transported to the superficial synthytium to be eliminated there.

[Rostellar organ or Taenia crassiceps (Cestoda: Taeniidae) larvae]. / Zheleza khobotka lichinok Taenia crassiceps (Cestoda: Taeniidae).

There are glandular elements of syntitial structure in parenchyma of scolex base of T. crassiceps larvae. They are located behind the suckers at the invaginated state of scolex. Perikaryons of gland contain dense rodshaped, spheric granules and great accumulations of electron-dense substance in vacuoles. The same types of secretary product are found in the rostellar tegument. The glandular elements are mostly developed in the period of the formation of rostellar hooks, but they are well expressed too in mature larvae thus providing morphofunctional specialization of rostellar tegument.

[Ultrastructure of the cyst wall of Aploparakis polystictae and A. furcigera (Cestoda, Cyclophyllidaea) metacestodes]. / Ul'trastruktura stenki tsisty metatsestod Aploparakis polystictae i A. furcigera (Cestoda, Cyclophyllidaea).

The development of the additional membrane (exocyst) from the caudal appendage in diplocysts does not change essentially the structure of the cyst's wall in metacestodes of the genus Aploparaksis. In cytoplasmic connections between cytons and the surface syncytium there are two autonomous enough systems of transport: microtubes opening to the surface of tegument and matrix of bridges which proceed to the matrix of external syncytium. In addition to cytons, in the cyst's wall there are cells with an enlarged granulated endoplasmic network, which are miofibroblasts, secretory cells performing an unclear function, protonephridia and cells limiting the cavity of the cyst of the layer. Differences in the larval morphology of both species are quite negligible and can be due to their age peculiarities.

Ultrastructure of the cyst of Hymenolepis diminuta larvae.

Electron microscopical studies of the cyst of 1-month-old H. diminuta larvae revealed considerable thickening of the superficial syncytium of tegument and formation of a large number of cavities and canals. The cytoplasm of the tegument is filled with microtubules produced by cytons of parenchymal layer which are analogs of tonofibrils. These peculiarities, together with numerous processes of the external fibrous layer, are regarded as adaptative to the changes of the hydrostatic pressure of the hemocoel of the intermediate host. The superficial syncytium is covered with microvilli and keeps polycellular cytoplasmatic bonds with cytons, which ensures energetic and plastic requirements for the stabilization of the hypertrophied syncytium and its physiological regeneration. Accumulations of fibres identical with those of the connective tissue were found in the cytons of the tegument. The cyst parenchyma consists mostly of cells with widened canals of granular endoplasmic reticulum associated with the microfibrils and production of fibrous filaments. The internal fibrous layer is produced by typical fibroblasts. The tegument of the cercomer is thinner and is considered to be less differentiated.

[Ultrastructure of the cercomere of the cysticercoid, Trichocephaloides megalocephala]. / Ul'trastruktura tserkomera tsistitserkoida Trichocephaloides megalocephala.

The cercomere of the larvae of Trichocephaloides megalocephala is formed exclusively by tegumentary tissues. The cytons of the tegument contain a great number of ribosomes, developed Golgi complex and numerous mitochondria that is indicative of the intensive synthesis, protein substances first of all. A distinct secretion of multivesicular membranes into subtegumentary space and further secretion of vesicles through the distal portion of the tegument into the external cyst cavity was observed. The main function of the cercomere is a production of the ground substance which apparently fulfils a protective function as it is suggested for glycocalix.

[Morphology and development of the cysticercoids of Paricterotaenia porosa (Cestoda: Dilepididae)]. / Morfologiia i razvitie tsistitserkoidov Paricterotaenia porosa (Cestoda: Dilepididae).

Studies of the development of Paricterotaenia porosa in its intermediate host Chironomus sp. were carried out. At 20 degrees C the development of the larva is completed in 24 days. The primary cavity is formed in 9 days, the separation of the cercomere anlage--in 11 to 12 days and the invagination of the larva--in 19 days. The larval development of P. porosa is characterized by its passing in the cavity of the external cyst, by the complete separation of anlages of the body of the larva and cercomere at the metamere stage and by the intensive growth of the cercomere after the invagination of the larva. The analysis of the cercomere structure suggests its protective function.

[Histochemical study of the cysticercoids of cestodes of the genus Aploparaksis Clerc, 1903 (Hymenolepididae)]. / Gistokhimicheskoe izuchenie tsistitserkoidov tsestod roda Aploparaksis Clerc, 1903 (Hymenolepididae)

Hystochemical methods were employed in order to study the distribution of succinic dehydrogenase, glucose-6-phosphate-dehydrogenase, alcaline, acidic phosphatases, lipids, fatty acids, glycogen and neutral. mucopolysaccharides in larvae of three species of cestodes: A. birulai, A. polystictae, A. xemae. A high concentration of succinic dehydrogenase was recorded from the tissue of the tail, scolex and neck. Glycose-6-phosphatdehydrogenase was found in great quantity only in the external parenchyma of the neck of A. polystictae. Here accumulations were observed of lipids which apparently are the products of excretion. The glycogen localization coincides with the distribution of succinis dehydrogenase. The activity of phosphatases is concentration in the structures of the tail and external membranes of cysticercoids, the acidic phosphatase being dominant. It was concluded that aerobic oxidation dominates in larvae and substances are principally transported through the tail area and excretory aperture.

[Distribution of some enzymes in totally stained preparations of cestodes]. / Raspredelenie nekotorykh énzimov v total'no okrashennykh preparatakh tsestod

The distribution of succinic dehydrogenase, (see article), glucose-6-phosphat-dehydrogenase, alkaline and acid phosphatases and glucose-6-phosphatase was studied by means of the incubation of whole cestodes. Succinic dehydrogenase, NAD-diaphorase and glucose-6-phosphatdehydrogenase are connected in general with the fixating apparatus of the scolex and genital organs; phosphatases -- with the integument tissues, excretory system and calcareous corpuscles. The results obtained are in complete agreement with the available data on the distribution of the enzymes studied. The incubation method of whole cestodes can be useful for field works.