Rostellar apparatus of Fernandezia spinosissima (von Linstow, 1894) (Cestoda, Cyclophyllidea, Davaineidae): microanatomy and fine structure

The rostellar apparatus of Fernandezia spinosissima is examined by light and transmission electron microscopy. It is described as composed of rostellum, pseudoproboscis, and two groups of glandular syncytia, one in the rostellum and the other inwards to the rostellum and the pseudoproboscis. The rostellum is a discoid cushion with muscular walls. There are numerous thin vertical muscular fibres and glandular syncytia inside it. Its tegument has slender microtriches. Peripherally, the rostellum is encircled by thin muscle fibres that protrude anteriorly between rostellar hooks and group posteriorly to form retractors. The rostellar hook guards are associated with a complicated network of muscles and nerves. The pseudoproboscis is a thick-walled ring around the apical part of the scolex adjacent to the rostellum. Its tegument has microtriches with modified spines that are interpreted as accessory spines. The walls of the pseudoproboscis possess a loose structure of parallel muscular fibres and glandular processes. The glandular syncytia, interpreted as modified tegumental perikarya, have basophilic cytoplasm and stain positively for protein and carbohydrate. They form cellular processes, which protrude to reach to the tegument. These results provide structural details characterising one of the rostellar types recognized in the order Cyclophyllidea, i.e. the davaineid rostellar apparatus.     

Blocking variant surface glycoprotein synthesis alters endoplasmic reticulum exit sites/Golgi homeostasis in Trypanosoma brucei

The predominant secretory cargo of bloodstream form Trypanosoma brucei is variant surface glycoprotein (VSG), comprising ~10% total protein and forming a dense protective layer. Blocking VSG translation using Morpholino oligonucleotides triggered a precise pre‐cytokinesis arrest. We investigated the effect of blocking VSG synthesis on the secretory pathway. The number of Golgi decreased, particularly in post‐mitotic cells, from 3.5 ± 0.6 to 2.0 ± 0.04 per cell. Similarly, the number of endoplasmic reticulum exit sites (ERES) in post‐mitotic cells dropped from 3.9 ± 0.6 to 2.7 ± 0.1 eight hours after blocking VSG synthesis. The secretory pathway was still functional in these stalled cells, as monitored using Cathepsin L. Rates of phospholipid and glycosylphosphatidylinositol‐anchor biosynthesis remained relatively unaffected, except for the level of sphingomyelin which increased. However, both endoplasmic reticulum and Golgi morphology became distorted, with the Golgi cisternae becoming significantly dilated, particularly at the trans‐face. Membrane accumulation in these structures is possibly caused by reduced budding of nascent vesicles due to the drastic reduction in the total amount of secretory cargo, that is, VSG. These data argue that the total flux of secretory cargo impacts upon the biogenesis and maintenance of secretory structures and organelles in T. brucei, including the ERES and Golgi.      

Cultivation of boar spermatogonia on Sertoli cells

We studied the in vitro effect of Sertoli cells on boar spermatogonia isolated from the testes of 60-day-old crossbred boars. In order to enrich the culture with spermatogonia, the cells were purified by density gradient centrifugation with the use of Percoll gradient followed by separation based on adhesive capacities of cells. We found lipid drops stained by Oil Red O in Sertoli cells. The experiments showed that the cultivation of boar spermatogonia in the presence of Sertoli cells (for up to 35 days) provide the same way of differentiation as in testes in natural conditions. After 10 days of cultivation, spermatogenic cells form groups, chains, and suspension clusters. By this time, spermatogenic colonies are formed; we analyzed the expression of Nanog and Plzf genes in these colonies by real-time PCR. The expression rate of Nanog gene in experimental cell clones obtained by the short-term cultivation of spermatogonia cells in the presence of Sertoli cells was 200 times higher than in freshly isolated spermatogonia cells. The product of Plzf gene expression was found both in freshly isolated spermatogenic cells and in cell clones obtained in vitro. After long-term cultivation of spermatogonia on Sertoli cells, we observed in vitro differentiation to the lineage of spermatogenesis and formation of separate motile sperm cells after 30–33 days. At this stage, the cell population was heterogeneous. In the absence of Sertoli cells, the differentiation of boar spermatogonia cells in culture stopped after 7 days of cultivation. The data show that the cultivation of boar spermatogonia cells on Sertoli cells contributes to their in vitro differentiation to the lineage of spermatogenesis and can help to obtain boar sperm cell culture.     

Electroretinography in the diagnosis of thallium intoxication

Appearance of dystrophic alterations in the retina was carried out by administering 0.2 ml 12 mM of tallium chloride solution into the vitreous humour of 9 rabbits. Electroretinographic examination revealed a decline in the b wave either decreasing 2-3 times or entirely disappearing as early as on day 2 after the administration of tallium chloride. Electron microscopic investigation suggested that photoreceptors of the retina were initial by involved in the pathological process. Namely, the external segments of the photoreceptors were found to be reduced, indicating impairment of the formation of photoreceptor disks, which is known to proceed continuously under normal conditions. In the absence of an electroretinogram (ERG), the photoreceptor layers were shown to have disappeared completely. An examination of 28 subjects who were exposed to tallium and its compound at work revealed impaired retinal electrogenesis, as evident from subnormal ERG responses. This was of a functional nature and became more pronounced as occupational exposure time increased. The fact that the internal retinal layers and the 3-rd neurone remained intact, as suggested by the electrical sensitivity of the eye and lability of the optic nerve as well as by static perimetry, correlated with the EM findings obtained in experiments. Ophthalmobiomicroscopic examination of 12 eyes yielded data on characteristic changes in the lens when visual functions remained intact. These findings suggest that changes in the ERG may be indicative of initial preclinical symptoms of tallium intoxication and as such can be used when persons exposed to it in industry receive check-ups.     

Combined effect of some physical and chemical factors

The effect of simultaneous exposure to noise and dimethylformamide (DMF), noise and xylol and also vibration and lead on the metabolism of the myocardium of albino rats was studied. Combined effect of the factors was examined by the method of bifactorial design of the experiment. The animals were exposed to noise, intensity 46, 85 and 95 dB (2 and 4 hours), DMF in doses of 0.25, 1.00 and 5.00 ml . kg-1 (5 days in a week), and xylol in a concentration of 300 mg . m-3 (4 hours, 5 days in a week) for a period of 1.5 months, as also to vibration, intensity 100 Hz, 4 m . sec-2 (2 hours) and lead acetate in a dose of 20 mg . kg-1 (daily for a period of 10 days). The activity of GlDG, SucDG, LDG, G6PDG, G6P-ase, PGM and CytO in the myocardium of experimental and control animals was examined. Disturbances in metabolic and energy processes in the heart muscle were established after both isolated and combined exposure to the effect of the factors. Results of bifactorial variance analysis demonstrate that combined effect of noise and DMF results in not only independent effect of the two factors, but also in their interaction. Isolated effect of two factors (vibration and lead) can be assessed according to the relationship of some enzymes; their interaction can be noticed in GlDG, ATP-ase and G6P-ase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cestode communities in non-breeding populations of four grebe species (Aves: Podicipedidae) from the Bulgarian Black Sea coast.

Cestode communities in Podiceps cristatus, P. grisegena, P. nigricollis and Tachybaptus ruficollis during their migrations and overwintering are studied at the Bulgarian Black Sea coast. The infracommunities exhibit high richness, abundance and dominance, and low diversity and similarity. The component communities have a similar taxonomic structure at the levels higher than species, a small number of core species and a high portion of grebe specialists in the richness and abundance. The comparison with cestode communities in grebes from Canada (Stock & Holmes, 1987) reveals several differences and similarities. The higher richness and abundance of the infracommunities in Canada are explained by the constant conditions of breeding habitats enhancing higher transmission rates. At the component community level, there is a significant difference between the two species lists. The degree of parasite exchange among the grebe species in Bulgaria is lower. Several characters of cestode component communities in grebes do not depend on either historical factors or different habitats. These are the similar patterns of the taxonomic structure at the levels higher than species, almost the same list of generalists, the participation of specialists of anatids, and the leading role of grebe specialists in the structure.     

Application of immobilized horseradish peroxidase onto modified acrylonitrile copolymer membrane in removing of phenol from water

A non-modified and modified with NaOH and ethylenediamine ultrafiltration membranes prepared from AN copolymer have been used as carriers for the immobilization of horseradish peroxidase (HRP) enzyme. The amount of bound protein onto the membranes and the activity of the immobilized enzyme have been investigated as well as the pH and thermal optimum, and the thermal stability of the free and immobilized HRP. The experiments have proved that the modified membrane is a better support for the immobilization of HRP enzyme. The latter has shown a greater thermal stability than the free enzyme.A possible application has been studied for reducing phenol concentration in water solutions through oxidation of phenol by hydrogen peroxide, in the presence of free and immobilized HRP enzyme on modified AN copolymer membranes. A higher degree of the phenol oxidation has been observed in the presence of the immobilized enzyme. A total removal of phenol has been achieved in the presence of immobilized HRP at concentration of the hydrogen peroxide 0.5 mmol L^?1 and concentration of the phenol in the model solutions within the interval 5–40 mg L^?1. A high degree of phenol oxidation (95.4%) has been achieved in phenol solution with 100 mg L^?1 concentration in the presence of hydrogen peroxide and immobilized HRP, which demonstrates the promising opportunity of using the enzyme for bioremediation of waste waters, containing phenol.The immobilized HRP has shown good operational stability. Deactivation of the immobilized enzyme to 50% of the initial activity has been observed after the 20th day of the enzyme operation.     

New-generation Skulachev ions exhibiting nephroprotective and neuroprotective properties

A mitochondria-targeted chimeric compound consisting of a rhodamine derivative linked to a plastoquinone molecule (10-(6′-plastoquinonyl)decylrhodamine, SkQR1) was studied under conditions of acute brain or kidney damage. A protective effect of this compound was demonstrated in a model of focal brain ischemia, rat kidney ischemia/reperfusion, myoglobinuria (rhabdomyolysis, or crush syndrome), and pyelonephritis. We found that a single intraperitoneal injection of SkQR1 diminishes the size of the ischemic zone in the brain and improves performance of a test characterizing neurological deficit in ischemic animals. An analog of SkQR1 not containing plastoquinone (C12R19) was not neuroprotective. The data show that SkQR1 is a nephroprotectant and neuroprotectant, which can be due to the antioxidative action of this Skulachev cation.