Features of Intracellular Signal Transduction in Neural Stem Cells under the Influence of Alkaloid Songorine, an Agonist of Fibroblast Growth Factor Receptors.

We performed a comparative in vitro study of the involvement of NF-κB, PI3K, cAMP, ERK1/2, p38, JAKs, STAT3, JNK, and p53-dependent intracellular signaling in the functioning of neural stem cells (NSC) under the influence of basic fibroblast growth factor (FGF) and FGF receptor agonist, diterpene alkaloid songorine. The significant differences in FGFR-mediated intracellular signaling in NSC were revealed for these ligands. In both cases, stimulation of progenitor cell proliferation occurs with the participation of NF-κB, PI3K, ERK1/2, JAKs, and STAT3, while JNK and p53, on the contrary, inhibit cell cycle progression. However, under the influence of songorin, cAMP- and p38-mediated cascades are additionally involved in the transmission of the NSC division-activating signal. In addition, unlike FGF, the alkaloid stimulates progenitor cell differentiation by activating ERK1/2, p38, JNK, p53, and STAT3.

A large anisotropic plasticity of L-leucinium hydrogen maleate preserved at cryogenic temperatures.

L-Leucinium hydrogen maleate crystals are very plastic at ambient conditions. Here it is shown that this plasticity is preserved at least down to 77 K. The structural changes in the temperature range 293-100 K were followed in order to rationalize the large anisotropic plasticity in this compound. To the best of our knowledge, this is the first reported example of an organic compound remaining so plastic at cryogenic conditions.

Psychopharmacological Effects of Alkaloid Z77 under Conditions of Posthypoxic Encephalopathy and Mechanisms of Their Development.

Psychopharmacological effects of atisine-type diterpene alkaloid Z77 were studied under conditions of experimental posthypoxic encephalopathy. The preparation had a pronounced cerebroprotective effect consisting in normalization of orientation and exploratory behavior and conditioned activity in experimental animals. These changes were accompanied by significant increase in the number of neural stem cells in the paraventricular region of the brain and markedly enhanced production of neurotrophic growth factors by neural tissue microenvironment cells.

Mechanisms of psychopharmacological effects of alkaloid Z77 under conditions of brain ischemia.

We studied the psychopharmacological effects of atisine-type diterpene alkaloid Z77 in a rat model of brain ischemia in the morning and at night. The type of developing locomotor disorders in animals was shown to depend on circadian rhythms. Administration of Z77 substantially corrected manifestations of psychoneurological symptoms. The parameters of orientation and exploratory behavior and conditioned reflex activity were normalized. The key role of receptors of neural stem cells to fibroblast growth factor in the realization of their growth potential under the influence of the alkaloid was demonstrated. Under in vitro conditions, antibodies to fibroblast growth factor receptor abolished the increase in the number of neural CFU caused by Z77 in the culture of intact cells from the paraventricular region of the brain.

Cerebroprotective and regenerative effects of alkaloid Z77 under conditions of brain ischemia.

We studied the psychopharmacological effects of atisine-type diterpene alkaloid Z77 in a rat model of cerebral ischemia. Pronounced cerebroprotective effect was found consisting in normalization of the orienting and exploratory activity and conditioned behavior associated with significant correction of morphological changes in the brain. The direct stimulatory effect of Z77 on neural stem cells was shown in vitro.

Role of NF-κB-dependent signaling in the growth capacity of mesenchymal progenitor cells under the influence of basic fibroblast growth factor.

We studied the in vitro role of NF-κB-dependent signaling in the growth capacity of mesenchymal progenitor cells upon stimulation by basic fibroblast growth factor. Proliferative activity of progenitor cells was suppressed by specifi c inhibitors of this transcription factor (NF-κB), oridonin and aurothiomalate. These inhibitors had no effect on differentiation of fibroblast CFU.

Role of receptors to fibroblast growth factor (FGF) on mesenchymal precursor cells in the realization of regenerative effects of alkaloid songorine.

We studied the mechanisms of regenerative (wound healing) effects of songorine associated with functional activation of mesenchymal progenitor cells. The key role of FGF receptors on these progenitor cells in the stimulation of realization of their growth potential under the effect of the alkaloid was demonstrated. Under in vitro conditions, the antibodies to FGF receptor abolished the songorine-induced increase in the number of fibroblast colony-forming units in bone marrow cell culture. The intensity of differentiation of mesenchymal precursors remained unchanged.

Mechanisms of napelline action stimulating the regeneration of hemopoietic tissue in cytostatic myelosuppression.

Pronounced regenerative effects of alkaloid napelline extracted from Aconitum baicalense on granulocytic hemopoiesis were revealed in the model of cytostatic myelosuppression. Activation of functions of hemopoietic progenitor cells along with increased feeder capacity of the stromal elements in the hemopoiesis inducing microenvironment with decreased levels mesenchymal progenitor cells in the bone marrow are the mechanisms underlying the hemostimulating action of this substance.

In vitro encystment of Himasthla elongata cercariae (Digenea, Echinostomatidae) in the haemolymph of blue mussels Mytilus edulis as a tool for assessing cercarial infectivity and molluscan susceptibility.

Infectivity of Himasthla elongata cercariae to mussels, their second intermediate hosts, and resistance by these hosts to infection were assessed on the basis of the cercariae's ability to encyst in mussel haemolymph in vitro. A series of experimental in vivo infections of mussels with batches of cercariae, each batch released from a different single infected mollusc and referred to as a clone (due to their shared genotype), demonstrated that the results of the in vitro tests corresponded to the actual indices of infectivity/susceptibility of the parasites and their hosts. Most cercarial clones had high infectivity, with a few clones having very high or, at the other extreme, very low infectivity. A similar pattern was revealed in mussel resistance to cercarial infection. Most of the molluscs tested were moderately susceptible to cercarial infection, but at each extreme a small fraction (less than 10%) displayed very high or very low susceptibility. It was shown that there were no totally compatible or totally incompatible 'cercaria clone/mussel' combinations. Results obtained are compared with the data on intra-population variability using the characters parasite infectivity/host compatibility for trematode/mollusc-first intermediate host associations. Results are made relevant to actual infection levels in mussel settlements at the White Sea.

[Clonal variability in longevity of the cercariae of Himasthla elongata (Trematoda: Echinostomatidae)].

The study was carried out on Himasthla elongata cercariae shed by infected Littorina littorea snails. The infected periwinkles were collected from the settlement with the low prevalence of H. elongata. As shown earlier with the use of AFLP (Amplified Fragment Length Polymorphisms) method, rediae groups in all the infected periwinkles of this settlement arise from the infection of a mollusc with a single miracidium. Therefore, the cercariae shed by an infected mollusc have the same genotype or, in other words, represent a clone. The LT50 (the time during which 50% of cercariae perish in the experimental dish) were measured experimentally for cercariae Himasthla elongata belong to different clones. The investigated parameter demonstrated a high level of interclonal variability. Two groups of cercarial clones were identified: one of them was characterized by the high level of intraclonal variability in LT50 and the second, by the low one. It is assumed that the observed heterogeneity may be stipulated by different degrees of mitotic recombinations during formation of different cercarial clones.

[Clonal variability in expression of geo- and photoorientation in cercariae of Himasthla elongata (Trematoda: Echinostomatidae)].

The study was carried out on Himasthla elongata, a digenean common in the coastal ecosystems of the northern European seas. This species utilises intertidal prosobranchs Littorina spp. as the first intermediate host, bivalves (in the White Sea, Mytilus edulis) as the second intermediate host and gulls as the final host. The periwinkles Littorina littorea infected with H. elongata rediae (parthenogenetic generations) were sampled in the intertidal of the White Sea (66 degrees 20' N, 33 degrees 38' E) and used as the source of cercariae. Periwinkles were collected from the settlement with the low prevalence of H. elongata. As shown earlier with the use of AFLP (Amplified Fragment Length Polymorphisms) method, rediae groups in all the infected periwinkles of this settlement arise from the infection of a mollusc with a single miracidium. Therefore, the cercariae shed by an infected mollusc have the same genotype or, in other words, represent a clone. Photo- and geoorientation of cercariae originating from different clones and aged 1 h and 6 h were analysed separately. It was shown that in general the larvae of each clone followed the behavioural pattern characteristics of the species (positive geoorientation and negative photoorientation). However, the degree of expression of this typical behaviour was different in different clones. An especially high variability was observed in the manifestation of geoorientation (in several clones, most larvae demonstrated negative geoorientation). Differences in the distribution of cercariae in the illumination gradient were almost equally associated with the interclonal variability and the age of the larvae. On the whole, as the age of cercariae increased, the positive geoorientation became more prominent, whereas the ratio of cercariae with the typical (negative) photoorientation decreased. Statistical analysis revealed significant differences between the cercarial clones both in the initial manifestation of geo- and photoorientation and in the changes in the character of these reactions with the larval age. Taking into account that each cercarial clone investigated had the same genotype, it seems very likely that the interclonal differences noted in this study are hereditary. Maintenance of a rather high level of genetic polymorphism by the character "expression of orientation reaction" in trematode cercariae may enhance the chances for successful transmission of these larvae. Such variability increases the scale of cercarial dispersion in space and promotes the successful infection of the hosts, whose behaviour is also subject to intra- and inter-population variability. Besides, cercariae whose behaviour deviates from the basic behaviour of the species may play the role of the population's potential for colonisation of new species of animal hosts.