迴向自然的詩學

Thème: Folliculogenesis, oogenesis and superovulationAbstract + posterThe LH surge promotes prostaglandin E2 (PGE2) production within the preovulatory follicle. Oocytemicroenvironment levels of PGE2 affect the developmental competence after fertilization. This studyaimed to characterize the follicular fluid PGE2 enrichment during superovulation treatment. Six heifers(Holstein, 20.3 +/-0.85 months old) received FSH (Stimufol®, Reprobiol, Belgium): half dose, ie, 250 μgof porcine follitropin (pFSH), combined with 50 μg of porcine lutropin (pLH). At the rate of 8 injections,in degressive dose, spread over 4 days. PGF2α (Estrumate®, MSD Santé Animale, France) was injectedat the same time as the 5th injection of Stimufol®.LH peak was assumed to occur between 35 and 40hours after the PGF2α injection. Individual sampling of fluid from antral follicles was performed byovum pick up 12 hours before PGF2α injection and 60 hours after PGF2α injection. This protocol wasdesigned to allow the collection of fluids from ovarian follicle containing either a pre-matured or amatured oocyte. Each heifer was his own control as we took the "pre-matured" follicular fluid on a firstovary and the "matured" follicular fluid on the 2nd ovary, 3 days later. The punctures were repeatedtwice and were cross-checked for the next repetition to evaluate the impact of the ipsi or contralateralside of the corpus luteum (CL) on the follicular fluid composition. The volume of fluid was measured foreach punctured follicle. The PGE2 concentration of the follicular fluid was measured by Elisa (CaymanChemical) to determine the progress of terminal follicular differentiation. An average of 13 +/- 5.06 and28 +/-13.9 follicles were punctured per session/heifer for respectively pre-matured (n=78) and matured(n=169) follicles. The mean collected volume differed between the two groups (pre-matured: 0.229+/-0.213 ml/follicle; matured: 0.575+/-0.379 ml/follicle; two samples t-test, pval<0.0001). No effect of theside of CL on fluid volume was detected (2-way Anova, p=0.397). The PGE2 concentration wasdetermined in 25 pre-matured follicles and 127 matured follicles. The mean PGE2 concentrationsignificantly differed between the two groups of follicular fluids (pre-matured: 7.2 +/-7.5 ng/ml; matured:60.2 +/-58.6 ng/ml) No effect of the side of CL was detected (p=0.278). Surprisingly, there was no linearrelationship between fluid volume and PGE2 concentration (adjusted R-squared: -0.0002, pvalue=0.327). PGE2 concentrations were very spread out within the matured group. This importantdispersion (Interquartile range=58.6 ng/ml) indicated that despite follicle growth in response to hormonalstimulation (FSH/LH) the ability of follicular granulosa and cumulus cells to synthesize PGE2 wasimperfectly achieved. Only 48% of the follicular fluids in the mature group had higher PGE2 levels thanthose in the premature follicle group. In conclusion, despite the ability of the stimulation treatment topromote growth of many follicles, there was a great heterogeneity in terms of PGE2 synthesis. Thisalteration could represent defective signaling mechanisms that could impact the developmentalcompetence of the oocyte

Transcervical collection of bovine embryos up to Day 21: An 8-year overview

International audienceTranscervical embryo collection is used routinely in the bovine species throughout the world to collect Day 6 to Day 9 embryos (early embryos) for genetic selection. For research purposes, however, the collection of embryos at later stages of pregnancy, i.e., Days 12 to 21 (late embryos), is needed. So far, for the recovery of late embryos, females are euthanized and embryo collection is performed after recovery of the genital tract. To reduce the number of animals used and still provide valuable material for embryo research, we have therefore developed a transcervical technique to collect late embryos. The objective of this study was to compare embryo recovery results at early and late stages within our laboratory. Altogether, 232 cows were used for this study. One hundred forty-five flushes were performed to collect embryos from Days 6 to 9, and 251 flushes were performed to collect embryos from Days 12 to 21. For the early embryos, a classical three-way collection equipment was used. To collect the late embryos, the same equipment was used, but the extensible flexible catheter that goes inside the external rigid catheter was removed, so that larger embryos could be collected through the remaining larger hole (two-way collection). All females were submitted to ovum pick up to remove the dominant follicle and were subsequently superovulated with FSH. Luteolysis was induced 48 hours before artificial insemination. Two artificial inseminations were performed with frozen semen, 48 and 56 hours after PGF2α injection. Before embryo collection, cows were treated with an epidural injection of a local anesthetic drug. The presence of CL was checked, and they were counted by rectal palpation. For all collections, the cervix was prepared with the initial introduction of a dilator. Then, the catheter was introduced in one horn, and the cuff was inflated as low as possible. For the collection of late embryos, the flushing solution (30 mL) was injected slowly twice to suspend the embryos before flushing the horn with 500 mL, and the same operation was performed on the second horn. There was no significant difference in the number of embryos collected per flush in the early- and late-stage (758 embryos collected, 5.22 ± 6.02 per flush vs. 1238 embryos collected, 4.93 ± 5.07 per flush, respectively). The number of embryos collected per CL, however, was significantly lower in the early versus late group (0.39 ± 0.32% vs. 0.44 ± 0.34%, respectively). The late collection allowed the retrieval of full conceptuses (embryonic and extraembryonic tissues), even at very late stages such as Days 18 to 21. Careful collection is needed, however, so that conceptuses are not damaged or torn: the horn must be massaged gently and the flush should be ideally recovered in one single flow. This technique is a powerful tool to collect the late-stage embryos for research purposes. Because it is not traumatic, animals can be used again for the same procedure

8-Thioalkyl-adenosine derivatives inhibit Listeria monocytogenes NAD kinase through a novel binding mode

Increased resistance of pathogens to existing antibiotics necessitates the search for novel targets to develop potent antimicrobials. Biosynthetic pathways of several cofactors important for bacterial growth, such as nicotinamide adenine dinucleotide phosphate (NADP), have been proposed as a promising source of antibiotic targets. Nicotinamide adenine dinucleotide kinases (NADK; EC 2.7.1.23) are attractive for inhibitor development, since they catalyze the phosphorylation of NAD to NADP, which is an essential step of NADP metabolism. We previously synthesized diadenosine derivatives that inhibited NADK from two human pathogens, Listeria monocytogenes and Staphylococcus aureus, in the micromolar range. They behave as NAD mimics with the 5',5'-diphosphate group substituted by a 8,5' thioglycolic bridge. In an attempt to improve inhibitory potency, we designed new NAD mimics based on a single adenosine moiety harboring a larger derivatization attached to the C8 position and a small group at the 5' position. Here we report the synthesis of a series of 8-thioalkyl-adenosine derivatives containing various aryl and heteroaryl moieties and their evaluation as inhibitors of L. monocytogenes NADK1, S. aureus NADK and their human counterpart. Novel, sub-micromolar inhibitors of LmNADK1 were identified. Surprisingly, most LmNADK1 inhibitors demonstrated a high selectivity index against the close staphylococcal ortholog and the human NADK. Structural characterization of enzyme-inhibitor complexes revealed the original binding mode of these novel NAD mimics

Effets de l’exposition sub-chronique maternelle à des microplastiques de polyéthylène par ingestion dans un modèle murin

International audienc

Combining accelerometers and direct visual observations to detect sickness and pain in cows of different ages submitted to systemic inflammation

International audienceAbstract Cattle suffering from inflammatory infection display sickness and pain-related behaviours. As these behaviours may be transient and last only a few hours, one may miss them. The aim of this study was to assess the benefit of combining continuous monitoring of cow behaviour via collar-attached accelerometers with direct visual observations to detect sickness and pain-related behavioural responses after a systemic inflammatory challenge (intravenous lipopolysaccharide injection) in cows of two different ages, proven by clinical, physiological and blood parameters. Twelve cloned Holstein cows (six ‘old’ cows aged 10–15 years old and six ‘young’ cows aged 6 years old) were challenged and either directly observed at five time-points from just before the lipopolysaccharide injection up to 24 h post-injection (hpi) or continuously monitored using collar-attached accelerometers in either control or challenge situations. Direct observations identified specific sickness and pain behaviours (apathy, changes in facial expression and body posture, reduced motivation to feed) expressed partially at 3 hpi and fully at 6 hpi. These signs of sickness and pain behaviours then faded, and quicker for the young cows. Accelerometers detected changes in basic activities (low ingesting, low ruminating, high inactivity) and position (high time standing up) earlier and over a longer period of time than direct observations. The combination of sensors and direct observations improved the detection of behavioural signs of sickness and pain earlier on and over the whole study period, even when direct signs were weak especially in young cows. This system could provide great benefit for better earlier animal care

Exposition maternelle aux nanoparticules métalliques (Au-pvp, Ag, CeO2) par instillation: effets sur la fonction placentaire et le phénotype fœtal.

International audienc

PGE2 Supplementation of oocyte culture media improves the developmental and cryotolerance performance of bovine blastocysts derived from a serum-free in vitro production system, mirroring the inner cell mass transcriptome

International audienceThe culture media used throughout the in vitro production (IVP) of bovine embryos remain complex. The serum added to culture media in order to improve embryo development negatively impacts the cryotolerance of blastocysts. Periconceptional prostaglandin E2 (PGE2) signaling is known to exert prosurvival effects on in vitro -generated blastocysts. The purpose of the present study was to evaluate the effects on developmental and cryotolerance performance of a serum-free (SF) IVP system that included defined oocyte culture media supplemented or not with PGE2, versus serum-containing (SC) IVP. RNA-sequencing analysis was used to examine the gene expression of ICM derived under the different IVP conditions. We assessed the degree of cryotolerance of grade-I blastocysts during a three-day post-thaw culture by measuring survival and hatching rates, counting trophectoderm and inner cell mass (ICM) blastomere numbers. We also determined the proportion of ICM cells expressing octamer-binding transcription factor 4 protein (OCT4/POU5F1). We showed that grade-I blastocyst development rates under SF + PGE2 conditions were similar to those obtained under SC conditions, although the cleavage rate remained significantly lower. SC IVP conditions induced changes to ICM gene expression relative to several metabolic processes, catabolic activities, cell death and apoptosis. These alterations were associated with significantly higher levels of ICM cell death at day 7 post-fertilization, and lower survival and hatching rates after thawing. SF IVP conditions supplemented or not with PGE2 induced changes to ICM gene expression related to DNA replication, metabolism and double-strand break repair processes, and were associated with significantly larger ICM cell populations after thawing. SF + PGE2 IVP induced changes to ICM gene expression related to epigenetic regulation and were associated with a significantly higher proportion of ICM cells expressing OCT4. For the first time, our study thus offers a comprehensive analysis of the ICM transcriptome regulated by IVP culture conditions in terms of the cellular changes revealed during culture for three days after thawing

Phénotypage endométrial du transport des spermatozoïdes (PETS)

National audienc

Différenciation et reprogrammation épigénétique des cellules germinales mâles dans le testicule fœtal bovin

National audienc