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.     

Differentiation of circular vessels in isolated segments of Fraxinus excelsior

The differentiation of circular vessels was studied in stem segments which had passed winter dormancy and were stimulated by application of auxin in vitro. The circular vessels differentiated near the basal end of internodes. The prevailing form of circular vessels was a pair of cells connected by two perforations. Two-cell vessels never had only one perforation. The occurrence of two perforations strongly supports the view that auxin flux is a stimulus for vessel differentiation and not the very presence or concentration of auxin; the circular vessels developed as a results of a circular flux. In general, the circular vessels appeared in contact with rays. Their formation was delayed in comparison with that of normal vessels.     

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.