In vitro development of mouse pronuclear embryos to blastocysts in sequential media with and without co-culture of autologous cumulus cells

The objective of this study was to use mouse embryos as a model system to investigate the effect of co-culture of cumulus cells in Sydney IVF sequential media (Cook) on embryo development, based on the hypothesis that feeder cells in co-culture with a sequential medium could work synergistically to further improve in vitro culture conditions for mammalian preimplantation embryos. The culture systems described here were evaluated by the ability to consistently produce high blastocyst formation rates and high cell number per blastocyst. The role of embryo-to-cell contact was assessed by using Transwell inserts with transparent microporous membranes. Pronuclear embryos of ICR mice were cultured to blastocysts in Cook sequential media, with and without mouse primary cultures of cumulus cells, and with or without inserts. Blastocyst formation rates and cell numbers of in vitro developing embryos in the different culture systems were compared to each other, and to in vivo derived blastocysts. Blastocyst formation rates for Cook medium only was 27.8% (without inserts) and 32.9% (with inserts), whereas Cook-Cumulus cells in identical culture systems was significantly higher at 45.8% (without inserts, P<0.05) and 55.6% (with inserts, P<0.05). When the embryos are suspended above the bottom of the well, for Cook medium significantly lower blastocyst formation rates were observed at 4.2% compared to Cook-Cumulus cells at 17.5% (P<0.05). Mean cell numbers of blastocysts obtained in all co-culture systems were significantly higher (P<0.05) compared to those developing in culture medium only. Although the putative mechanism is as yet unexplained, the improved blastocyst formation rates and cell numbers in co-culture when there is direct contact between the embryo and the cell monolayer suggest that the close proximity between the feeder cells and embryos is in part responsible for these effects.     

Small nuclear ribonucleoprotein remodeling during catalytic activation of the spliceosome

Major structural changes occur in the spliceosome during its activation just before catalyzing the splicing of pre-messenger RNAs (pre-mRNAs). Whereas changes in small nuclear RNA (snRNA) conformation are well documented, little is known about remodeling of small nuclear ribonucleoprotein (snRNP) structures during spliceosome activation. Here, human 45S activated spliceosomes and a previously unknown 35S U5 snRNP were isolated by immunoaffinity selection and were characterized by mass spectrometry. Comparison of their protein components with those of other snRNP and spliceosomal complexes revealed a major change in protein composition during spliceosome activation. Our data also suggest that the U5 snRNP is dramatically remodeled at this stage, with the Prp19 complex and other factors tightly associating, possibly in exchange for other U5 proteins, and suggest that after catalysis the remodeled U5 is eventually released from the postsplicing complex as a 35S snRNP particle.     

Symbiotic nitrogen fixation in the alpine community of a lichen heath of the Northwestern Caucasus Region (the Teberda Reserve)

The symbiotic fixation of atmospheric nitrogen by leguminous plants in the alpine community of a lichen heath at the Teberda State Biosphere Reserve is well adapted to low soil temperature characteristic for the altitude of 2800 m a.s.l. For the determination of the N fixation by isotopic methods (the method of the natural ¹⁵N abundance and the method of isotopic ¹⁵N dilution), Trifolium polyphyllum was taken as the control plant. This plant was used as it does not form symbiosis with the nitrogen-fixing bacteria in the highlands of the Northern Caucasus Region. The contribution of the N fixation to the N nutrition of different leguminous plant species as determined by the natural ¹⁵N abundance method amounted to 28–73% at δ¹⁵N₀ = 0‰ and 46–117% at δ¹⁵N₀ = −1‰; for the determination of the N fixation by the method of the isotopic label’s dilution, it was 34–97%. The best correlation of the results obtained by these two isotopic methods was observed for the natural fractionation of the N isotopes in the course of the N fixation in the range of −0.5 to −0.7‰. The determination of the nitrogenase activity of the roots by the acetylene method confirmed the absence of N fixation in T. polyphyllum and its different contribution to the N nutrition of different species of leguminous plants.     

Use of the anticoccidial agent, tortrazuril (Baycox, Bayer) in coccidiosis in suckling pigs]

At present neonatal coccidiosis caused by Isospora suis is known to be an important disease in piglets. The coccidium I. suis was diagnosed as the causative agent of diarrhoeic disease in piglets on a large pig farm with continuous farrowing operation. The diagnosis of coccidiosis was based on clinical history, gross lesions, histopathology, stained impression smears and aided by detection of oocysts in the faeces. Coccidiosis was associated with diarrhoea in piglets at the age of five to fourteen days. The disease was characterized by variable morbidity and only a portion of the litters was usually affected at one time. The piglets appeared listless, and suffered from yellow watery scours progressing to yellow pasty scours over a three- to five-day period. The lack of response to common antimicrobial therapy, and/or vaccination of sows for E. coli was observed. The prophylactic and therapeutic efficacy of tortrazuril (Baycox, Bayer) against coccidiosis was evaluated in naturally infected piglets. Tortrazuril at a dose of 20 mg/kg, given perorally to each piglet on days 6 and 8 of age, proved to be efficacious in preventing clinical coccidiosis in piglets. Tortrazuril fully controlled the oocyst output, prevented the development of diarrhoea but not improved the weight gains in three-week-old piglets if compared to the untreated controls. The prophylactic and therapeutic efficacy of tortrazuril was compared with another drug--amprolium (Amprovin, MSD). Amprolium at a dose of 100 mg/kg, given perorally to piglets from day 6 to 8 of age, was not efficacious in preventing clinical porcine neonatal coccidiosis. Amprolium reduced the oocyst output, but not prevented the development of diarrhoea. Tortrazuril (Baycox, Bayer) is clearly effective against porcine neonatal coccidiosis caused by I. suis.     

Phosphorus in humus acids

The distribution of phosphorus among humus acid groups in different soil types was studied. It was shown that the binding of P with acid-soluble and-insoluble organic components is determined by the acid-base status of soils, which controls the predominant interaction of P with Fe and Al or with Ca and Mg, and the solubility of the resulting organic phosphates in acid and alkali. The major part of P is associated with the group of humic acids (HAs) in the acid soils and with fulvic acids (FAs) in the neutral and calcareous soils. During the fractionation of organic matter from acid soils, the amount of P redistributed from the HA to the FA group can increase with an increasing acid or alkaline impact on the soil, which breaks the bonds of the phosphorus-bearing organic components with metals.