Preliminary findings on carbohydrate metabolism of intact equine cumulus-oocyte complexes during in vitro maturation

Conference paper abstrac

Structural insights into the redox-switch mechanism of the MarR/DUF24-type regulator HypR.

Bacillus subtilis encodes redox-sensing MarR-type regulators of the OhrR and DUF24-families that sense organic hydroperoxides, diamide, quinones or aldehydes via thiol-based redox-switches. In this article, we characterize the novel redox-sensing MarR/DUF24-family regulator HypR (YybR) that is activated by disulphide stress caused by diamide and NaOCl in B. subtilis. HypR controls positively a flavin oxidoreductase HypO that confers protection against NaOCl stress. The conserved N-terminal Cys14 residue of HypR has a lower pK(a) of 6.36 and is essential for activation of hypO transcription by disulphide stress. HypR resembles a 2-Cys-type regulator that is activated by Cys14-Cys49' intersubunit disulphide formation. The crystal structures of reduced and oxidized HypR proteins were resolved revealing structural changes of HypR upon oxidation. In reduced HypR a hydrogen-bonding network stabilizes the reactive Cys14 thiolate that is 8-9 Å apart from Cys49'. HypR oxidation breaks these H-bonds, reorients the monomers and moves the major groove recognition α4 and α4' helices ∼4 Å towards each other. This is the first crystal structure of a redox-sensing MarR/DUF24 family protein in bacteria that is activated by NaOCl stress. Since hypochloric acid is released by activated macrophages, related HypR-like regulators could function to protect pathogens against the host immune defense

Effect of holding equine oocytes in meiosis inhibitor-free medium before in vitro maturation and of holding temperature on meiotic suppression and mitochondrial energy/redox potential

BACKGROUND: Evaluation of mitochondrial function offers an alternative to evaluate embryo development for assessment of oocyte viability, but little information is available on the relationship between mitochondrial and chromatin status in equine oocytes. We evaluated these parameters in immature equine oocytes either fixed immediately (IMM) or held overnight in an Earle’s/Hank’s’ M199-based medium in the absence of meiotic inhibitors (EH treatment), and in mature oocytes. We hypothesized that EH holding may affect mitochondrial function and that holding temperature may affect the efficiency of meiotic suppression. METHODS: Experiment 1 - Equine oocytes processed immediately or held in EH at uncontrolled temperature (22 to 27°C) were evaluated for initial chromatin configuration, in vitro maturation (IVM) rates and mitochondrial energy/redox potential. Experiment 2 - We then investigated the effect of holding temperature (25°C, 30°C, 38°C) on initial chromatin status of held oocytes, and subsequently repeated mitochondrial energy/redox assessment of oocytes held at 25°C vs. immediately-evaluated controls. RESULTS: EH holding at uncontrolled temperature was associated with advancement of germinal vesicle (GV) chromatin condensation and with meiotic resumption, as well as a lower maturation rate after IVM. Holding did not have a significant effect on mitochondrial distribution within chromatin configurations. Independent of treatment, oocytes having condensed chromatin had a significantly higher proportion of perinuclear/pericortical mitochondrial distribution than did other GV configurations. Holding did not detrimentally affect oocyte energy/redox parameters in viable GV-stage oocytes. There were no significant differences in chromatin configuration between oocytes held at 25°C and controls, whereas holding at higher temperature was associated with meiosis resumption and loss of oocytes having the condensed chromatin GV configuration. Holding at 25°C was not associated with progression of mitochondrial distribution pattern and there were no significant differences in oocyte energy/redox parameters between these oocytes and controls. CONCLUSIONS: Mitochondrial distribution in equine GV-stage oocytes is correlated with chromatin configuration within the GV. Progression of chromatin configuration and mitochondrial status during holding are dependent on temperature. EH holding at 25°C maintains meiotic arrest, viability and mitochondrial potential of equine oocytes. This is the first report on the effects of EH treatment on oocyte mitochondrial energy/redox potential

Thermophilic anaerobic oxidation of methane by marine microbial consortia

The anaerobic oxidation of methane (AOM) with sulfate controls the emission of the greenhouse gas methane from the ocean floor. AOM is performed by microbial consortia of archaea (ANME) associated with partners related to sulfate-reducing bacteria. In vitro enrichments of AOM were so far only successful at temperatures ⩽25 °C; however, energy gain for growth by AOM with sulfate is in principle also possible at higher temperatures. Sequences of 16S rRNA genes and core lipids characteristic for ANME as well as hints of in situ AOM activity were indeed reported for geothermally heated marine environments, yet no direct evidence for thermophilic growth of marine ANME consortia was obtained to date. To study possible thermophilic AOM, we investigated hydrothermally influenced sediment from the Guaymas Basin. In vitro incubations showed activity of sulfate-dependent methane oxidation between 5 and 70 °C with an apparent optimum between 45 and 60 °C. AOM was absent at temperatures ⩾75 °C. Long-term enrichment of AOM was fastest at 50 °C, yielding a 13-fold increase of methane-dependent sulfate reduction within 250 days, equivalent to an apparent doubling time of 68 days. The enrichments were dominated by novel ANME-1 consortia, mostly associated with bacterial partners of the deltaproteobacterial HotSeep-1 cluster, a deeply branching phylogenetic group previously found in a butane-amended 60 °C-enrichment culture of Guaymas sediments. The closest relatives (Desulfurella spp.; Hippea maritima) are moderately thermophilic sulfur reducers. Results indicate that AOM and ANME archaea could be of biogeochemical relevance not only in cold to moderate but also in hot marine habitats

Analyse der Schwangerschaftsabbruchsstatistik in der Bundesrepublik Deutschland in den Jahren 1977 bis 1988

StBA Wiesbaden(282) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Técnicas de reproducción asistida en caballos

Assisted reproductive technology (ART) refers to non-conventional methods for obtaining foals by obtaining isolated oocytes in problematic or geriatric mares. In this way, problems with the mare�s uterus or oviduct that limit proper sperm transport and survival, adequate fertilization, and consequently embryo transport are bypassed. There are two main methods to recover oocytes from a valuable mare � from the dominant preovulatory follicle, or from all visible follicles on the ovaries. In addition, there are two main methods to fertilize the recovered oocytes: in vitro, by intracytoplasmic sperm injection (ICSI) or in vivo, by transferring it to the oviduct of a previously inseminated recipient mare (Oocyte Transfer).As técnicas de reprodução assistida são métodos não-convencionais para a obtenção de potros de éguas problemáticas ou geriátricas, através da retirada de ovócitos viáveis. Assim, os problemas do útero ou do ovíduto que impedem o transporte e a sobrevivência de espermatozoides, a fertilização adequada e, consequentemente, o transporte do embrião são evitados. Existem principalmente dois métodos para coletar ovócitos em éguas � a partir do folículo pré-ovulatório dominante, ou de todos os folículos visíveis nos ovários. Há também dois métodos para fertilizar os ovócitos que foram obtidos: in vitro, através de injeção intracitoplasmática de espermatozoides (ICSI) ou in vivo, transferido-os para o oviduto de uma égua destinatária previamente inseminada (Transferência de ovócitos).Las técnicas de reproducción asistida son métodos no convencionales por los cuales se obtienen potros de yeguas problema o geriátricas mediante la obtención de oocitos viables. De esta manera, los problemas del útero o del oviducto que impiden un buen transporte y sobrevivencia de los espermatozoides, adecuada fertilización y consecuentemente transporte del embrión, son sobrepasados. Existen primordialmente dos métodos para colectar oocitos en yeguas � a partir del folículo pre-ovulatorio dominante o de todos los folículos visibles en los ovarios. Además existen dos métodos para fertilizar los oocitos que han sido obtenidos: in vitro, por inyección intracitoplasmatica de un espermatozoide (ICSI) o in vivo, al transferirlo al oviducto de una yegua receptora inseminada previamente (Transferencia de oocitos)