Biomedical subjects

Emilie Bonnet

Publications and source records attributed to Emilie Bonnet.

3 recordsLinked to original sources

PubMed2006

Characterization of rainbow trout egg quality: a case study using four different breeding protocols, with emphasis on the incidence of embryonic malformations.

The aim of this study was to set up a methodology to accurately evaluate the effects of various husbandry practices on a fish broodstock based on the developmental potential of the egg. For that purpose, long-short photoperiod manipulations (tested twice, PM1 and PM2 groups), spawning induction by injection of a GnRH analog (SI group), and a 16-day post-ovulatory ageing of eggs (POA group) were used in rainbow trout (Oncorhynchus mykiss). Females without any treatment were used as a control group. Survival at eying (E) and yolk-sac resorption (YSR) were recorded and malformations at YSR were monitored according to a detailed typology that included cyclopia, torsion, incomplete YSR, prognathia, and others. Egg weight was also monitored. A deleterious effect of photoperiod manipulation was observed on egg quality in both PM1 and PM2 groups. Incomplete YSR appeared as the predominant malformation while cyclopia type was nearly absent. In the SI group, a limited effect on egg quality was observed in comparison to the other experimental groups, although the percentage of normal alevins at YSR was significantly lower than in the control group. Finally, the most important effects on egg quality were observed in the POA group. The percentage of normal alevins was only 14+/-6% (mean+/-95% confidence interval) while the percentage of malformed embryos reached 49+/-11%. The proportion of cyclopia was significantly higher than in the control group. In conclusion, the type of egg quality alteration is extremely dependent on the applied breeding protocols, and the proposed methodology is able to discriminate those experimental conditions even when the impact on egg quality is limited.

Animals↗

PubMed2006

Mitochondrial reactive oxygen species are required for hypothalamic glucose sensing.

The physiological signaling mechanisms that link glucose sensing to the electrical activity in metabolism-regulating hypothalamus are still controversial. Although ATP production was considered the main metabolic signal, recent studies show that the glucose-stimulated signaling in neurons is not totally dependent on this production. Here, we examined whether mitochondrial reactive oxygen species (mROS), which are physiologically generated depending on glucose metabolism, may act as physiological sensors to monitor the glucose-sensing response. Transient increase from 5 to 20 mmol/l glucose stimulates reactive oxygen species (ROS) generation on hypothalamic slices ex vivo, which is reversed by adding antioxidants, suggesting that hypothalamic cells generate ROS to rapidly increase glucose level. Furthermore, in vivo, data demonstrate that both the glucose-induced increased neuronal activity in arcuate nucleus and the subsequent nervous-mediated insulin release might be mimicked by the mitochondrial complex blockers antimycin and rotenone, which generate mROS. Adding antioxidants such as trolox and catalase or the uncoupler carbonyl cyanide m-chlorophenylhydrazone in order to lower mROS during glucose stimulation completely reverses both parameters. In conclusion, the results presented here clearly show that the brain glucose-sensing mechanism involved mROS signaling. We propose that this mROS production plays a key role in brain metabolic signaling.

Animals↗

PubMed2004

Post-ovulatory ageing and egg quality: a proteomic analysis of rainbow trout coelomic fluid.

BACKGROUND: In fish, oocyte post-ovulatory ageing is associated with egg quality decrease. During this period, eggs are held in the body cavity where they bath in a semi-viscous liquid known as coelomic fluid (CF). CF components are suspected to play a role in maintaining oocyte fertility and developmental competence (egg quality). However, CF proteic composition remains poorly studied. Thus rainbow trout CF proteome was studied during the egg quality decrease associated with oocyte post-ovulatory ageing. METHODS: High resolution two-dimensional gel electrophoresis was used to analyze the proteome of rainbow trout (Oncorhynchus mykiss) CF in relationship with the egg quality decrease associated with oocyte post-ovulatory ageing. A first experiment was performed using CF pools originating from 17 females sampled at ovulation as well as 7, 14 and 21 days later. These observations were verified using a second set of CF pools originating from 22 females sampled 5 and 16 days following ovulation. RESULTS: Approximately 200 protein spots of 10-105 kDa molecular mass and 3-10 pI were detected in CF samples. Several protein spots, while undetected at the time of ovulation, exhibited a progressive and strong accumulation in CF during post-ovulatory ageing. After silver-staining and Matrix-Assisted Laser Desorption Time Of Flight (MALDI-TOF) mass spectrometer analysis, some of these protein spots were identified as lipovitellin II fragments. CONCLUSIONS: These observations suggest that egg protein fragments accumulate in the CF during the post-ovulatory period and could therefore be used to detect egg quality defects associated with oocyte post-ovulatory ageing.

Aging↗