Relation entre chronologie des échecs de gestation et anomalies de reprise de cyclicité postpartum chez la vache laitière

National audienc

Abnormal patterns of resumption of cyclicity after calving in Holstein cows: risk factors,relationships with the ultrasound appearance of the ovaries and with gestation failure after AI

 Twice weekly blood progesterone analysis was used to monitor resumption of ovarian cyclicity in 239 postpartum periods of 144 Holstein cows in one herd between D7 and D70 postpartum (PP). Calving season, low milk production and low BCS were risk factors for delayed cyclicity (DC: 16.3%). Retained placenta and metritis, early ovulation after calving and postpartum negative energy balance were identified as risk factors for prolonged luteal phase (PLP: 18.4%). At the same time, in 110 postpartum periods, ovaries were examined twice a week by ultrasonography. In normal cows (N: 56.5%), the first large follicle (>= 10mm) appeared 14.6 +/- 3.9 days after calving, ovulation occurred 28.9 +/- 9.5 days PP and the maximum diameter of the first corpus luteum (CL) was 24.9 +/- 4.9 mm. In DC cows, the interval between calving to the first large follicle tended to be longer than in normal cows (23.0 +/- 15.6 d; P=0.06). In PLP cows, the first large follicle was delayed (17.6 +/- 5.2 d, P<0.05), first ovulation occurred earlier (23.2 +/- 6.9 d PP, P<0.05), the maximum size of the first CL was not different from N cows (26.2 +/- 6.2 mm) despite its lifespan (33.6 +/- 13.8 days). Before first AI, cows not seen in oestrus or with a diagnosed abnormal progesterone profile were submitted to oestrus induction and synchronization treatment. The proportions of treated cows were 32.8, 62.9 and 60.5% in the N, DC and PLP groups of cows (significant difference between N and abnormal cows). In N cows, the interval from calving to conception was 117.3 +/- 60.6 days. Conception rate at first service (CR) was 31.3%, the incidences of early embryonic (EEM) and late embryonic-foetal mortality (LEM) were 47.9 and 33.3%. In DC cows, calving to conception interval was higher (144.0 +/- 67.3 d, P<0.05) than N cows. CR (28.6%) and EEM (60%) incidence were not different from N cows. In PLP cows, calving to conception interval was not different (132.8 +/- 62.0 d), CR was lower (16.3%, P=0.05) and LEM incidence tended lobe higher (56.3%. P<0.10) than in N cows. In conclusion, transrectal ultrasonography is not effective in distinguishing normal CL from CL associated with a prolonged luteal phase. PLP seems to have a negative effect on CR and on the incidence of LEM which should be investigated on a larger scale in Holstein cows

Phénotypage endométrial du transport des spermatozoïdes (PETS)

National audienc

Energy and lipid metabolism gene expression of D18 embryos in dairy cows is related to dam physiological status

We analyzed the change in gene expression related to dam physiological status in day (D)18 embryos from growing heifers (GH), early lactating cows (ELC), and late lactating cows (LLC). Dam energy metabolism was characterized by measurement of circulating concentrations of insulin, glucose, IGF-1, nonesterified fatty acids, β-hydroxybutyrate, and urea before embryo flush. The metabolic parameters were related to differential gene expression in the extraembryonic tissues by correlation analysis. Embryo development estimated by measuring the length of the conceptuses and the proportion of expected D18 gastrulating stages was not different between the three groups of females. However, embryo metabolism was greatly affected by dam physiological status when we compared GH with ELC and GH with LLC but to a lesser extent when ELC was compared with LLC. Genes involved in glucose, pyruvate, and acetate utilization were upregulated in GH vs. ELC conceptuses (e.g., SLC2A1, PC, ACSS2, ACSS3). This was also true for the pentose pathway ( PGD, TKT), which is involved in synthesis of ribose precursors of RNA and DNA. The pathways involved in lipid synthesis were also upregulated in GH vs. ELC. Despite similar morphological development, the molecular characteristics of the heifers' embryos were consistently different from those of the cows. Most of these differences were strongly related to metabolic/hormone patterns before insemination and during conceptus free-life. Many biosynthetic pathways appeared to be more active in heifer embryos than in cow embryos, and consequently they seemed to be healthier, and this may be more conducive to continue development

Structural analysis of a nanoparticle containing a lipid bilayer used for detergent-free extraction of membrane proteins

In the past few years there has been a growth in the use of nanoparticles for stabilizing lipid membranes that contain embedded proteins. These bionanoparticles provide a solution to the challenging problem of membrane protein isolation by maintaining a lipid bilayer essential to protein integrity and activity. We have previously described the use of an amphipathic polymer (poly(styrene-co-maleic acid), SMA) to produce discoidal nanoparticles with a lipid bilayer core containing the embedded protein. However the structure of the nanoparticle itself has not yet been determined. This leaves a major gap in understanding how the SMA stabilizes the encapsulated bilayer and how the bilayer relates physically and structurally to an unencapsulated lipid bilayer. In this paper we address this issue by describing the structure of the SMA lipid particle (SMALP) using data from small angle neutron scattering (SANS), electron microscopy (EM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (NMR). We show that the particle is disc shaped containing a polymer “bracelet” encircling the lipid bilayer. The structure and orientation of the individual components within the bilayer and polymer are determined showing that styrene moieties within SMA intercalate between the lipid acyl chains. The dimensions of the encapsulated bilayer are also determined and match those measured for a natural membrane. Taken together, the description of the structure of the SMALP forms the foundation for future development and applications of SMALPs in membrane protein production and analysis.[Figure not available: see fulltext.] © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.SCOPUS: ar.jinfo:eu-repo/semantics/publishe