Ability of acceptance for bacteriophages during verotoxin production by bacilli of the Enterobacteriaceae family]

Lysogenised verotoxigenic strains are the source of structural genes of verocytotoxins (stx-1 and stx-2) for the others intestinal bacili. The aim of the study was to estimate the ability of transfer of bacteriophages induced with UV irradiation from reference verotoxigenic strains of E. coli O157:H7 (CB571 and EDL933) into 125 wild-strains of bacili of Enterobacteriaceae family. None of tested recipient strains showed the production of cytotoxin on Vero and HeLa cell lines, what was acknowledged as the lack of six genes. Contrary to the laboratory strain of E. coli C600 none of 125 tested recipient strains accepted the phages. Obtained lysogenised laboratory strains of E. coli C600/CB571 and E. coli C600/EDL933, besides of the ability to produce verotoxins (with the presence of stx-1 and stx-2 genes), did not differ phenotypically and genotypically from parent strain of E. coli C600. The estimation of the ability to transfer of phages carried stx-1 and/or stx-2 genes was impossible because of too small number of tested wild strain of bacili or because of really low frequency of acceptation of phages by wild strains of intestinal bacili.     

The effect of the leucopyrokinin analogue: [2-8]-leucopyrokinin on central opioid receptors in rats

The antinociceptive effect of intracerebroventricular injections of [2–8]-leucopyrokinin (LPK), a truncated leucopyrokinin analogue, was determined in rats, by means of a tail immersion test. We found a significant antinociceptive effect of three i.c.v. doses of [2–8]-LPK: 1, 5 and 10 nmol. Pre-treating animals with naloxone hydrochloride (1 mg/kg i.p.) completely blocked the effect of two high doses of [2–8]-LPK. To determine the sub-types of opioid receptors involved in [2–8]-leucopyrokinin-induced analgesia we injected specific blockers of μ-, δ- and κ-receptors namely, β-funaltrexamine hydrochloride, naltrindole hydrochloride and nor-binaltorphimine dihydrochloride, respectively, prior to [2–8]-leucopyrokinin at equimolar doses. We conclude that the antinociceptive effect of [2–8]-leucopyrokinin is mediated mainly by central μ- and δ-opioid receptors.     

Asymmetric induction in the [4+2]cycloaddition of cyclopentadiene and furan to chiral derivatives of fumaric acid.

[4+2]Cycloaddition reactions of cyclopentadiene (1a) and furan (1b) to N,N'-fumaroyldi[(2R)-bornane-10,2-sultam] (2) and to N,N'-fumaroyldi[(2R)-bornane-10,2-(2'-phenyl-pyrazol-3'-one)] (3) are presented. A correlation between the solvent polarity and the logarithm of the diastereoisomer ratio (dr) was found for the uncatalyzed [4+2]cycloaddition of 1a to 3.     

Effects of oocyte quality, semen donor and embryo co-culture system on the efficiency of blastocyst production in goats

The aim of the study was to determine whether the selection of immature oocytes by a combination of cumulus-oocyte-complexes (COCs) morphology and staining with brilliant cresyl blue (BCB) would be helpful in selecting developmentally competent oocytes, and thereby increase the efficiency of blastocyst production from ovarian oocytes of FSH-primed, adult goats. In a second experiment the interaction between oocyte quality and semen donor was assessed. In a third experiment the usefulness of Vero cells for co-culture with goat embryos was investigated. In the pool of morphologically normal COCs recovered from ovaries following slicing (21.9+/-11.0), the mean rate of COCs classified as BCB+ was 85.6%, and the BCB- was approximately 11%. Oocytes classified as grade 1 and BCB+ exhibited the highest developmental competence (P<0.001) after in vitro maturation and fertilization compared with oocytes of grade 1 BCB- and grade 2 BCB+ or BCB-. There were no significant differences in developmental competence in grade 2 oocytes, regardless of BCB coloration. No significant differences in embryo cleavage and blastocyst formation rates among three bucks were observed when morphologically normal, BCB+ oocytes were used. For all tested bucks, differences in embryo production efficiency were related only to the oocyte quality. Similar blastocyst rates were developed from embryos co-cultured with goat oviduct epithelial cells (34.3%) and with Vero cells (33.3%). These results show that the most important criterion for selection of COCs before maturation is the visual assessment of morphological features. Staining with BCB of COCs recovered from adult goats does not enhance efficiency of selection of developmentally competent oocytes for IVF.     

Testicular morphology and expression of aromatase in testes of mice with the mosaic mutation (Atp7a mo-ms)

The aim of this study was to determine whether testicular cells of mice with the mosaic mutation, associated with abnormal copper metabolism, are able to aromatize androgens to estrogens, and what is the putative role of estrogens in the gonad of the mutant male. Mosaic is a lethal mutation; affected males usually die on about day 16. Those, which survive to reach sexual maturity, are valuable research subjects. In testes of young and adult mutants, histological analysis revealed the presence of many degenerating seminiferous tubules besides normal-looking ones. Additionally, high numbers of apoptotic germ cells were observed, especially in young mutants when compared with the controls. Positive immunostaining for aromatase was found in cultured Leydig cells and testicular sections of both control and mutant males. The intensity of immunostaining was always stronger in the mosaic mice. In both groups, Western-blot analysis revealed the presence of aromatase protein as a single band of approximately 55 kDa. In the mosaic males, levels of testosterone in cultured Leydig cells, whole testes, and in blood plasma were lower than in those of the respective controls. On the contrary, estradiol concentrations were always higher in the mutants. Both in vivo and in vitro studies indicate that morphological and functional changes in the testes of the mosaic mice mainly result from defective copper metabolism. The higher level of endogenous estrogens can additionally enhance morphological alterations within the testes. It seems also likely that excess estrogens may affect the survival rate of the mosaic males.     

The role of oxidative stress induced by growth regulators in the regeneration process of wheat

As part of work to optimize the regeneration processes of winter wheat callus culture the effects of two auxins (2,4-D, IAA), two cytokinins (kinetin, zeatin), and the fungal mycotoxin zearalenone, were tested individually in vitro using embryo-, and inflorescence-derived callus. To determine the role of oxidative stress in cell regeneration, changes in the basic antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and peroxidases (PODs) were investigated. In general, zearalenone (ZEN) was found to be more effective than cytokinin treatments for inducing shoot production, whereas auxins suppressed the regeneration process. Regenerating callus showed higher induction of these antioxidant enzymes in comparison with non-regenerating callus. SOD, CAT and POD activities were higher in callus derived from inflorescence than in callus derived from immature embryo. Activities of SOD, CAT and POD in culture derived from immature embryos were depending on type of growth regulator in medium. The highest enzyme activities were observed in non-regenerating tissues after auxins treatment and in regenerating tissues after cytokinins treatment. The effect of ZEN was similar to that of cytokinins. One MnSOD band and two Cu/ZnSOD bands were detected in all cultures. Changes in SOD izoform patterns occurred in callus culture on media with auxins and ZEN, but not on media with cytokinins. Our results suggest that callus regeneration is associated with reactive oxygen species production induced by specific growth regulators. Reactive oxygen species under the control of cellular antioxidant machinery can mediate signalling pathways between exogenously applied growth regulators and the induction and/or creation of the direction of morphogenesis.     

<Emphasis Type="Italic">Paenibacillus</Emphasis> strain MP-1: a new source of mutanase

A mutan-degrading bacterium, closely related to Paenibacillus curdlanolyticus, was isolated from soil. It produced 0.4 U mutanase ml⁻¹ in 2 days in shake-flask cultures when bacterial mutan was the sole carbon source. Mutanase activity was optimal at pH 6.2 and 45°C over 1 h and was stable between pH 5.8 and 12 at 4°C for 24 h and up to 40°C for 1 h. Mutan produced by Streptococcus mutans was rapidly hydrolyzed by this enzyme. The hydrolysis of mutan (1 g l⁻¹) resulted in 17% saccharification over 2 h and, at the same time, glucan was entirely solubilized.     

Interaction of AT1 receptors and V1a receptors-mediated effects in the central cardiovascular control during the post-infarct state

Experimental objectives. Because myocardial infarct is associated with overactivation of brain angiotensin II (ANG II) and vasopressin (AVP) V1a receptors we decided to determine whether AT1 and V1a receptors-mediated effects of ANG II and AVP interact in central cardiovascular control during the post-infarct state. Four groups of infarcted and four groups of sham-operated conscious rats entered the study. Results. In the infarcted rats cerebroventricular infusion of AT1 (AT1ANT, losartan) and V1a antagonist {V1aANT,d(CH(2))(5)[Tyr(Me)(2)Ala-NH(2)(9)]VP} and combined infusion of both these compounds performed 4 weeks after induction of the infarct significantly and comparably reduced mean arterial blood pressure (MABP) in comparison to control experiments (artificial cerebrospinal fluid infusion). In the sham rats MABP was not affected by any of the infusions. In control experiments MABP and HR responses to an alarming air jet stress were significantly higher in the infarcted than in the sham rats. Both responses were normalized with the same effectiveness by administration of AT1ANT, V1aANT and AT1ANT+V1aANT. In the sham rats administration of these compounds did not affect MABP and HR responses to stress. Conclusion: The results provide evidence for interaction of AT1 and V1a receptors-mediated effects of ANG II and AVP in the central cardiovascular control during the post-infarct state.