Stevioside Has the Maximum Biological Activity among Natural Stevia Diterpenes.

The concentrations of steviol and its derivatives stimulating the growth of wheat plants were measured: 10-8 for stevioside and 10-9 М for steviol and isosteviol. It was found that stevioside increased the activity of amylolytic enzymes and protein content, as well as frost tolerance of the roots of wheat seedlings. Thus, stevioside can be recommended for the development of complex phytopreparations for stimulating the growth processes and increasing the resistance of wheat plants to low temperatures.

Molecular Heterogeneity of Lectins in Wheat Seedlings under the Action of Stevioside and Heavy Metals.

The effect of the diterpene glycoside stevioside and high concentrations of heavy metals on the molecular heterogeneity of lectins was studied in seedlings of Kazanskaya 560 winter wheat cultivar. Stevioside induced the emergence of a new 45-kDa lectin. Cultivation of wheat seedlings in CdSO4 and ZnSO4 solutions resulted in the emergence of the protein with Mr = 88 kDa. We detected the presence of both lectins in seedlings during combined treatment with stevioside and heavy metals.

Stevioside prevents oxidative stress in wheat seedlings.

This is the first study on the effect of stevioside, a diterpene glycoside that is a new promising plant growth regulator, on the antioxidant and photosynthetic systems of seedlings of the winter wheat cultivar Kazanskaya 560. Stevioside has been demonstrated to cause a decrease in the malondialdehyde formation rate, an increase in the activities of antioxidant enzymes (peroxidase and ascorbate peroxidase), and the accumulation of proline and carotenoids. Apparently, this integrated effect of stevioside can prevent oxidative stress caused by adverse environmental factors in plants.

Glutamate and nicotinic receptor interactions in working memory: importance for the cognitive impairment of schizophrenia.

This article reaches across disciplines to correlate results in molecular, cellular, behavioral, and clinical research to develop a more complete picture of how working memory (WM) functions. It identifies a new idea that deserves further investigation. NMDA glutamate receptors (NMDAR) are critical for memory function. NMDAR inhibition effectively reproduces principal manifestations of schizophrenia (SP), such as WM impairment and GABAergic deficit (mainly reduction of glutamic acid decarboxylase 67 (GAD67) and parvalbumin (PV) content). Nicotine and selective α7 nicotinic acetylcholine receptor (nAChR) agonists reduce WM impairments in patients with SP and reverse WM deficits in animals treated with NMDAR antagonists. The mechanism of this effect is unknown. Importantly, WM recovery occurs even before restoration of NMDAR blockade-induced molecular alterations, including reduced GAD67 in interneurons. Our insight into the cognitive-enhancing effect of α7 nAChR agonists, particularly in the animal models of SP, combines reviews of recent findings on glutamate and nicotinic receptor expression in the neuronal circuits involved in WM, the properties of these receptors, their implication in WM regulation, generation of rhythmic neuronal activity, resulting in a proposed hypothesis for further investigations. We suggest that (1) cortical/hippocampal interneurons, particularly PV positive, play a crucial role in WM and that impairment of these cells in SP could be behind the WM deficit; (2) activation of α7 nAChRs could restore calcium signaling and intrinsic properties of these interneurons, and associated with these events, computational capacity, gamma rhythmic activity, and WM would also be restored.

Serine-phosphorylated STAT1 is a prosurvival factor in Wilms' tumor pathogenesis.

Wilms' tumor (WT), one of the most common pediatric solid cancers, arises in the developing kidney as a result of genetic and epigenetic changes that lead to the abnormal proliferation and differentiation of the metanephric blastema. As activation of signal transducers and activators of transcription (STATs) plays an important role in the maintenance/growth and differentiation of the metanephric blastema, and constitutively activated STATs facilitate neoplastic behaviors of a variety of cancers, we hypothesized that dysregulation of STAT signaling may also contribute to WT pathogenesis. Accordingly, we evaluated STAT phosphorylation patterns in tumors and found that STAT1 was constitutively phosphorylated on serine 727 (S727) in 19 of 21 primary WT samples and two WT cell lines. An inactivating mutation of S727 to alanine reduced colony formation of WT cells in soft agar by more than 80% and induced apoptosis under conditions of growth stress. S727-phosphorylated STAT1 provided apoptotic resistance for WT cells via upregulation of expression of the heat-shock protein (HSP)27 and antiapoptotic protein myeloid cell leukemia (MCL)-1. The kinase responsible for STAT1 S727 phosphorylation in WT cells was identified based upon the use of selective inhibitors as protein kinase CK2, not p38, MAP-kinase kinase (MEK)1/2, phosphatidylinositol 3'-kinase, protein kinase C or Ca/calmodulin-dependent protein kinase II (CaMKII). The inhibition of CK2 blocked the anchorage-independent growth of WT cells and induced apoptosis under conditions of growth stress. Our findings suggest that serine-phosphorylated STAT1, as a downstream target of protein kinase CK2, plays a critical role in the pathogenesis of WT and possibly other neoplasms with similar STAT1 phosphorylation patterns.

[Activity of lectins of winter wheat seedlings infected with mycoplasma and treated with salicylic acid].

Changes in activity of soluble and cell wall lectins have been revealed in seedlings of winter wheat Triticum aestivum L. cultivar Mironovskaya 808 after infection with mycoplasma Acholeplasma laidlawii 118. The protective effect of salicylic acid was manifested as negating the bursts of lectin activity induced by mycoplasma infection.

[Lectin and mitotic activities in root meristems of winter wheat under oryzalin effect].

The effect of oryzalin, a microtubule polymerization inhibitor (10 MM), on lectin and mitotic activities (mitotic index and duration of mitotic phases) was studied in unhardened (23 degrees C) and hardened (7 days, 2-3 degrees C) winter wheat seedlings. Three wheat cultivars differing in their frost tolerance were compared. Oryzalin treatment (3 h) decreased activity of soluble lectins, increased activity of cell wall lectin mitotic index. Under these conditions, prolongation of anaphases and disappearance of telophases were detected. Plant hardening reduced the sensitivity of cell wall lectins and mitotic activity to the cytoskeleton inhibitor due, presumably, to the appearance of cold-stable microtubules. Plant growing and hardening with oryzalin stopped mitoses and caused the appearance of polyploid cells and cells with micronuclei. These abnormalities were preserved after hardening. The results obtained demonstrate an important role of microtubules in adaptation of plants to low temperature.

[Change in lectin specificity of winter wheat seedlings in the course of infection with mycoplasms]. / Izmenenie lektinovoi aktivnosti prorostkov ozimoi pshenitsy pri infitsirovanii mikoplazmami.

The activity of soluble lectins in leaves and roots of seedlings of winter wheat (Triticum aestivum L.) cultivar Mironovskaya 808 increased 1 day and 2 days, respectively, after infection with the mycoplasma Acholeplasma laidlawii 118. Analysis of acid-soluble proteins of wheat leaves by PAGE revealed the appearance of 22- and 20-kDa polypeptides, the disappearance of a 14-kDa polypeptide, and an increase in the content of polypeptides with molecular weights of 76, 48, 25, and 18 kDa. The 18-kDa polypeptide is a subunit of wheat germ agglutinin. A change in the activity of lectins may be a nonspecific response of plants to infection with the pathogen.

[Different sensitivity of inbred mice to hepatocarcinogen ortho-aminoazotoluene may be due to differences in the negative control mechanisms of hepatocyte proliferation]. / Raznaia chuvsvitel'nost' myshei inbrednykh linii k gepatokantserogenu orto-aminoazotoluolu mozhet byt' sviazana s razlichiiami v mekhanizmakh negativnogo kontrolia prolifaratsii gepatotsitov.

A most convenient model to study mechanisms of live organism response to chemical carcinogens is tumor induction in murine liver by aminoazodyes, in particular by ortho-aminoazotoluene (OAT). We studied both early and late stages of hepatocarcinogenesis on several lines of inbred mice differing in sensibility to OAT. By means of autoradiography, we examined proliferative activity of hepatocytes obtained from the liver of sensitive (A/He, DD, SWR) and resistant to OAT AKR, CC57Br, BALB/c lines of mice, which were injected carcinogen. The level of p53, p21Cip1, bax, mdm2, cyclin G, gadd45 genes expression in the liver of mice of different lines given OAT injection was studied by multiplex PCR method. Carcinogen caused a decrease of hepatocyte proliferative activity induced by partial hypatectomy (PHE), and an increase in p53, p21Cip, bax, mdm2, and cyclin G genes within mice of A/He, DD and SWR lines. Cell fusion experiments on hepatocytes obtained from regenerating murine liver sensitive to A/He line carcinogen and given long-time OAT administrations with resting and proliferating fibroblasts of NIH 3T3 mice revealed no obvious suppression of DNA synthesis in heterokaryons. Unlike, in fusion experiments on serum-stimulated fibroblasts with hepatocytes obtained from the liver of BALB/c line mice also given OAT suppression of DNA synthesis in stimulated fibroblasts in heterokaryons was observed 15 days following PHE. These results enable us to conclude that OAT administrations break negative endogenous mechanisms of hepatocyte proliferation control in the liver of mice sensitive to carcinogenes.

STRA13 interacts with STAT3 and modulates transcription of STAT3-dependent targets.

STRA13 is a pVHL-dependent bHLH transcription factor up-regulated on the mRNA level in multiple cancer cell lines and implicated recently in the regulation of immune cell homeostasis and autoimmunity. In searching for STRA13-interacting proteins with oncogenic potential by the yeast two-hybrid screening, we identified STAT3 beta as a STRA13-binding partner. We showed that STRA13 binds predominantly to phosphorylated (active) STAT3 alpha and beta isoforms via its HLH and C-terminal regions. We also found that STRA13 was able to activate transcription from STAT-dependent cis-elements. Expression of endogenous STRA13 was shown to be cytokine-inducible, consistent with STRA13 involvement in STAT-dependent transcription regulation. We demonstrated that the STAT3-regulated promoter of the pro-apoptotic Fas gene was activated upon STRA13 over-expression and that co-expression of STRA13 with STAT3 beta or STAT3 alpha modulated the transcriptional outcome. Forced expression of STRA13 induced apoptosis, in agreement with the STRA13 activation effect on the Fas promoter. Simultaneous expression of STRA13 and STAT3 beta resulted in alleviation of the STRA13 pro-apoptotic effect. Thus, for the first time, we identify STRA13 as a STAT3 partner and provide a consistent line of evidence for STRA13 involvement into regulation of apoptosis via the STAT pathways.

[mRNA level and cytochrome P450 1A activity in the liver of C57BL mice induced by various xenobiotics]. / Uroven' mRNK i aktivnost' tsitokhromov P450 1A v pecheni myshei linii C57BL pri induktsii razlichnymi ksenobiotikami.

The rate of hepatic cytochrome P450 Cypla1 and Cyp1a2 induction was investigated in C57BL male mice during induction with o-aminoazotoluene (OAT), benzo[a]pyrene (BP) and 1,4-dihydroxyanthraquinone (AQ). The Cypla1 mPNA level determined by quantitative RT-competitive PCR increased more than three orders of magnitude during induction with OAT and BP compared with untreated animals and remained unchanged during induction with AQ. The Cypla2 mRNA level was only 8.5, 18.7 and 1.9 times higher during induction with OAT, BP and AQ respectively than in untreated mice. At the same time 7-Ethoxyresorufin-O-deethylase (EROD) and 7-Methoxyresorufin-O-demethylase (MROD) activities of Cypla were also investigated in liver. The increase of Cypla1 mRNA level correlated with the increase of EROD activity. This suggests involvement of the transcriptional mechanism of the inducibility of this enzyme. In the case of Cypla2 there was insignificant increase of its mRNA level but high catalytic activity registered in liver in response to injection of the inductor of MR metabolism. This can imply the posttranscriptional mechanism of Cypla2 regulation. During induction with AQ the Cypla1 mRNA level remained unchanged, but the EROD activity increased almost 20-fold. The latter suggests insufficient specificity of this substrate for Cypla1. Thus, on the basis of the data obtained, the mRNA level can be considered as more accurate estimation of Cypla1 and Cypla2 inducibility, than the determination of the enzyme activity.

Species specific hepatocarcinogen inhibition of the glucocorticoid induction of tyrosine aminotransferase gene in mouse and rat liver.

3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) is a potent hepatocarcinogen in rats and a weak carcinogen in mice, whereas o-aminoazotoluene (OAT) is a potent hepatocarcinogen in mice but weak hepatocarcinogen in rats. They significantly suppress glucocorticoid induction of tyrosine aminotransferase (TAT) in the liver of sensitive animals and have minor effect on the induction of this enzyme in the liver of resistant animals (3'-MeDAB-treated mice and OAT-treated rats). The inhibitory effect of these carcinogens is realized at the level of gene transcription (decreased accumulation of TAT mRNA). This effect is mediated via reduction of DNA-binding activity of transcription factor HNF3 (without decrease of its content) without any involvement of the glucocorticoid receptor. It was shown that carcinogens influence DNA-binding activity of HNF3 via an unknown nuclear factor.

[Pulmonary carcinogenesis susceptibility-associated single-nucleotide polymorphisms in K-ras intron 2 affect the binding of factor Gata-6 but not gene expression]. / Assotsiirovannyi s chuvstvitel'nost'iu k kantserogenezu v legkikh tochkovyi polimorfizm v introne 2 gena K-ras vliiaet na sviazuvanie s faktorom GATA-6, no ne na uroven' ékspressii gena.

The sequence of K-ras intron 2, which has been associated with lung tumor susceptibility in inbred mouse strains, was analyzed in susceptible strain GR and in resistant strains PT and UT. In the latter case, the intron had a tandem repeat of a 37-bp sequence with variant GC of its two single-nucleotide polymorphisms (SNPs), as earlier reported for resistant strains AKR, C57BL/c, and C3H/A. Strain GR did not differ in intron structure from susceptible strains A/He and ICR, having one copy of the 37-bp sequence with SNP variant CA. By gel retardation assay, a DNA probe corresponding to "susceptible" allele CA of K-ras region 278-307 formed an additional complex with nuclear proteins extracted from the lungs, as compared with probes corresponding to the "resistant" GC and "intermediate" CC alleles. With specific antibodies, the protein binding to the susceptible allele was identified as transcription factor GATA-6. Reverse transcription with subsequent multiplex PCR did not reveal a significant difference in K-ras expression for susceptible and resistant strains. The results suggest that SNPs of K-ras intron 2 do not affect the level of K-ras expression but do control the binding of GATA-6, which plays an important role in lung differentiation.

[Effect of modification of cell calcium status on lectin activity]. / Aktivnost' lektinov pri izmenenii kal'tsievogo statusa kletok.

Effects of oryzalin (10 microM), an inhibitor of microtubule polymerization, on the activity of soluble and cell wall lectins were studied in 7 day-old seedlings of unhardened (23 degrees C) and cold acclimated (7 days at 2-3 degrees C) winter wheat (Triticum aestivum L.). Seedlings were grown in the presence of 25 microM and 1 mM Ca2+, 500 microM verapamil, 250 microM chlorpromazine or without modifiers of calcium status in the medium. Inhibitor of the microtubule polymerization inhibitor, likely as inhibitors of Ca(2+)-signal, decreased the activity of soluble lectins and increased that of cell wall lectins. Apparently, injury of microtubule phosphorylation results in a more considerable microtubule disorganization, than that observed after oryzalin effect. A low Ca2+ concentration (25 microM) depressed, while a high concentration (1 mM) prompted microtubule sensibility to oryzalin. Such an effect of high Ca2+ concentration may be related to destabilizative action of Ca(2+)-calmodulin in these conditions, because chlorpromazine decreased oryzalin-induced increase in the activity of cell wall lectins with 1 mM Ca2+. It is concluded that the activity of cell wall lectins depends on the microtubule status that is regulated by calcium signal.