126. IMPLICATIONS FOR FETAL AND PLACENTAL DEVELOPMENT FOLLOWING MITOCHONDRIAL PERTURBATION IN THE EMBRYO

2009 ◽  
Vol 21 (9) ◽  
pp. 45
Author(s):  
S. Wakefield ◽  
M. Lane ◽  
M. Mitchell
Keyword(s):  
Mitochondrial Function ◽  
Weight Ratio ◽  
Threshold Effect ◽  
Blastocyst Stage ◽  
Placental Weight ◽  
Placental Development ◽  
Cell Stage ◽  
Crown Rump Length ◽  
Fetal Survival ◽  
Placental Efficiency

The environment an embryo is exposed to can profoundly influence peri- and post-natal development despite having some capacity to adapt. Whilst the mechanisms responsible remain largely unknown, mitochondria are a likely target. In this study we deliberately perturbed mitochondrial function in the mouse embryo, using a model we have established that shows step-wise changes in embryo metabolism and development. The aim of this study was to provide direct evidence implicating mitochondrial dysfunction in the embryo with perturbed fetal and placental development. Zygote stage embryos were recovered from superovulated female mice and cultured in control conditions to the 2-cell stage. Embryos were then allocated to one of three treatments; control media (0μM-AOA), 5μM or 50μM of the known mitochondrial inhibitor, Amino-Oxyacetate, in the absence of pyruvate (5μM-AOA, 50μM-AOA). Embryos were cultured to the blastocyst stage, then transferred to pseudopregnant recipients, with fetal and placental parameters measured on day 18 of pregnancy. Implantation rates and fetal survival for both 5μM-AOA and 50μM-AOA was comparable to control embryos. For 5μM-AOA there was a significant reduction in placental weight (P=0.02) but normal fetal weight, and a significant increase in fetal: placental weight ratio (P=0.002) relative to the control, suggesting increased placental efficiency. When mitochondria were further perturbed (50μM-AOA), the fetuses and placentas were both considerably compromised: that is, decreased fetal and placental weights (P=0.002), reduced placental diameter (P=0.03) and decreased fetal crown rump length (P=0.07). This study demonstrates that mitochondrial function in the embryo impacts on peri-natal development, providing compelling evidence for mitochondrial function involvement in the mechanisms underpinning “embryo programming”. This data suggests a threshold effect, whereby embryos can only adapt up until a point after which development is compromised. Further elucidating these mechanisms is important for understanding how maternal environments and embryo culture systems determine development of future offspring.

scholarly journals Selection for placental efficiency in swine

2004 ◽  
Author(s):  
◽  
Henry Mesa Echeverri
Keyword(s):  
Selection Index ◽  
Genetic Selection ◽  
Reproductive Traits ◽  
Placental Weight ◽  
High Survival ◽  
Genetic Trend ◽  
Crown Rump Length ◽  
Placental Function ◽  
Selection For ◽  
Placental Efficiency

With the overall goal of increasing profitability by increasing litter size, two lines of pigs were divergently selected for four generations on an index of reproductive traits (n = 193 litters). The selection index (SI) included total born (TB), birth weight (BW) and placental weight (PW) and was designed to increase (H line) or decrease (L line) BW:PW (placental efficiency; PE). (Co)variance components were estimated for direct and maternal additive effects by using an animal model with MTDFREML procedures. Breeding values were estimated (EBV) for individual BW (n = 2,111), PW (n = 2,006), PE (n = 1,677), and SI (n = 1,677). Direct heritability estimates were 0.03, 0.25, 0.18, 0.11 and 0.08 for BW, PW, PE, SI, and TB, respectively. Genetic divergence was 20.7 g, 0.24, 0.11, and 0.07 pigs per generation for PW, PE, SI, and TB, respectively (P less 0.01), but not significant for BW. Thus, PW and PE are susceptible to change by genetic selection; however, the genetic trend for TB unexpectedly was positive in the L line The phase two objective was to evaluate correlated responses in conceptus development and placental function in these lines. Sows were remated within line to produce 50 generation-four litters for evaluation at d 30, 50, 70, 90, and 110 of gestation.Fetal weight did not differ between lines from d 30 to 90, but was lower in H than L at d 110 (P = 0.02). Crown-rump length did not differ between lines from d 30 to 70, but was longer in H than L at d 90 (P = 0.09) and shorter at d 110 (P = 0.04). PW did not differ between lines from d 30 to 90, but was lower in H than L at d 110 (P less than 0.01). PE did not differ between lines at any gestational age. These results suggest that in western breeds, a reduction in placental weight through selection is not accompanied by physiological changes to improve placental function and may result in decreased prenatal survival. The farrowing data were used in phase three to determine factors influencing survival at farrowing (FS) and weaning (WS). These traits were considered traits of the piglet and scored 1 for piglets alive at those time points or 0 if dead. Estimates of direct heritability were 0.16 and 0.18 and of maternal heritability were 0.14 and 0.10 for FS and WS, respectively. Logistic regressions indicated BW, PW, their interaction, and TB can be used as predictors FS and WS. In the presence of BW, PE does not improve the prediction of survival. These results suggest possible selection for increased FS and WS. A piglet's BW, PW, its litter average BW, and the individual's deviation from that average can be used to produce piglets with high survival probability.

261. Disruption of mitochondrial function in the blastocyst alters expression of the chromatin remodeler ATRX

2008 ◽  
Vol 20 (9) ◽  
pp. 61
Author(s):  
S. L. Wakefield ◽  
A. N. Filby ◽  
M. Lane ◽  
M. Mitchell
Keyword(s):  
Mitochondrial Function ◽  
Metabolic Regulation ◽  
Culture Media ◽  
Maternal Diet ◽  
Cell Number ◽  
Early Embryo ◽  
Placental Development ◽  
Blastocyst Development ◽  
Cell Stage ◽  
Embryo Metabolism

Exposure of an embryo to suboptimal environments, including poor embryo culture media or inadequate maternal diet, can disrupt fetal and placental development and whilst the exact mechanisms responsible remain unknown, perturbed embryo metabolism has been implicated. We propose that stress applied to an early embryo causes mitochondrial dysfunction, resulting in a permanent epigenetic change. Thus the aim of this study was to determine the affect of directly perturbing mitochondria in the embryo, on development, metabolism and expression of the ATP-dependant chromatin remodelling protein, ATRX. Zygotes collected from gonadotrophin stimulated C57BL/6xCBA mice were cultured to the two-cell stage and then exposed to one of three treatments; control medium (C), medium lacking pyruvate (-P; embryos dependant on the mitochondrial Malate Aspartate Shuttle, MAS) or medium lacking pyruvate plus 5µM amino-oxyacetate (AOA), a specific MAS inhibitor (-P+AOA). Blastocyst development and metabolism were assessed by determining cell number and allocation, glycolysis, and ATP:ADP ratio. Relative gene expression of ATRX, was examined using RT PCR. Embryos dependant on the MAS alone (-P) had significantly decreased blastocyst development (87.1% v. 98.2%, P < 0.05), with a compensatory increase in glycolysis (0.20 v. 0.07 pmol/cell/hr, P < 0.001) despite a decrease in ATP:ADP (0.10 v. 0.13, P < 0.06), relative to the control. Inhibition of the MAS (-P+AOA) further reduced blastocyst development,(77.3%, P < 0.001) and decreased ATP:ADP (0.08, P < 0.004), but there was no change in glycolysis relative to control embryos (0.09 pmol/cell/hr, P = 0.3). Expression of ATRX was significantly increased for –P+AOA embryos relative to the control (1.63 v. 1.0, P < 0.007) but did not differ for –P embryos (1.1). This study demonstrates that direct perturbations of mitochondrial function in the embryo compromises its metabolic regulation and blastocyst development, and the expression of the epigenetic modulator ATRX. Further studies are underway to elucidate the implications of disrupted metabolic control and this epigenetic modulator on pregnancy outcomes.

scholarly journals Beta-hydroxy-beta-methylbutyrate (HMB) Supplementation to Mouse Dams in Gestation Does Not Affect Fetal Weight Variation of Offspring or Placental Development (P09-003-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Anna Clarke ◽  
Nathan Horn ◽  
Gerald Shurson ◽  
Christopher Faulk ◽  
Lee Johnston
Keyword(s):  
Dietary Treatment ◽  
Placental Weight ◽  
Fetal Weight ◽  
Placental Development ◽  
Funding Sources ◽  
Weight Variation ◽  
Pulse Dose ◽  
Pregnant Mice ◽  
Placental Efficiency ◽  
Dietary Treatments

Abstract Objectives The objective of this study was to determine if supplementing mouse dam diets with β-hydroxy-β-methylbutyrate (HMB) calcium salt throughout gestation would improve pup fetal weight uniformity and placental development. Methods Data were collected from 27 genetically identical mouse dams and their offspring. Dams were assigned to one of 4 dietary treatments: Control (CON; n = 7), Low HMB (LHMB; 3.5 mg/g diet; n = 6), High HMB (HHMB; 35 mg/g diet; n = 7), and low HMB pulse dose (PUL; 3.5 mg/g diet; n = 7) from days 6 to 10 of gestation. All dams were fed a swine lactation derived corn-soy diet with HMB supplementation only during gestation. Dams were euthanized on day 18 of gestation. Results Dietary treatment did not affect total number of pups per litter, but fetal weight was greater (P < 0.05) for pups from PUL dams (1.05 ± 0.02 g) than LHMB (0.94 ± 0.02 g) or HHMB (0.95 ± 0.02 g) dams. Within-litter variation (standard deviation and coefficient of variation) and range of fetal weights was not different among treatments. Differences between the median fetal weight within litter and weight of the lowest weight fetal pup in each litter were similar among treatments. Supplementation with HMB did not influence weight of placentae or area of the placental labyrinth. Placental efficiency, measured as fetal weight/placental weight, was less (P < 0.05) for LHMB dams compared to CON dams. Conclusions In conclusion, dietary supplementation of HMB for pregnant mice had no effect on fetal weight variation within litter. Supplementing diets with β-hydroxy-β-methylbutyrate had no effect on placental weight or labyrinth area but reduced placental efficiency in dams fed LHMB. Funding Sources This research has been supported and funded by BioMatrix International, Princeton, MN.

87 EVALUATION OF MITOCHONDRIAL FUNCTION IN SINGLE CLONED MINIATURE PIG EMBRYOS BY MEASURING OXYGEN CONSUMPTION

2007 ◽  
Vol 19 (1) ◽  
pp. 161
Author(s):  
S. Sugimura ◽  
M. Yokoo ◽  
K.-I. Yamanaka ◽  
T. Wakai ◽  
H. Abe ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Mitochondrial Function ◽  
Blastocyst Stage ◽  
Miniature Pig ◽  
Cell Stage ◽  
Significant Difference ◽  
Lower Oxygen ◽  
Energy Synthesis ◽  
Mitochondrial Uncoupler

Mitochondria are organelles that produce energy for embryogensis. Their function [oxidative phosphorylation (OXPHOS) and electron transport] is regulated by intercommunication with the nucleus. In somatic cell nuclear transfer (SCNT) embryos, incomplete reprogramming may lead to dysfunction of the intercommunication before or after embryonic activation, or both, although it is unknown whether reprogramming for energy synthesis is required. In the previous report (Abe et al. 2004 J. Mamm. Ova Rec. 21, 22), we developed a noninvasive method using a scanning electrochemical microscopy (SECM) for measurement of oxygen consumption that provides more direct information about mitochondrial function (Trimarch et al. 2000 Biol. Reprod. 62, 1866–1874). In the present study to evaluate mitochondrial function in individual miniature pig SCNT embryos, we measured oxygen consumption by SECM. Oocytes in pig ovaries collected from the local slaughterhouse were matured for 44 h in NCSU23 and used as recipient. After SCNT with fetal miniature pig fibroblasts, reconstructed embryos were cultured in vitro in NCSU23 or PZM-3. Oxygen consumption in single 2- and 4-cell-stage embryos, morulae, and blastocysts were measured, and the values were compared with those derived from IVF. All data were analyzed by ANOVA. In IVF embryos, oxygen consumption was lowest at the 2- and 4-cell stages, and reached a peak at the blastocyst stage on Day 5. However, there were significant differences (P &lt; 0.05) in blastocysts between NCSU23 and PZM-3: 0.61 � 0.14 vs. 0.83 � 0.18 at Day 5, 0.53 � 0.14 vs. 0.70 � 0.24 at Day 6, 0.47 � 0.11 vs. 0.73 � 0.20 � 10-14 mol s-1 at Day 7, respectively. In contrast, SCNT embryos showed no increase in oxygen consumption during pre-implantation stages in the 2 media, but there was a significant difference (P &lt; 0.05) at the 2-cell stage between NCSU23 and PZM-3 (0.35 � 0.09 vs. 0.43 � 0.10, respectively). Comparison of the Day 5 IVF and SCNT blastocysts cultured in PZM-3 showed no difference in total cell numbers but significantly (P &lt; 0.05) lower oxygen consumption in SCNT (0.83 � 0.18 vs. 0.40 � 0.13 � 10-14 mol s-1, respectively). After treatment with 1 �M CCCP (mitochondrial uncoupler) or 1 mM NaCN (mitochondrial electron transporter inhibitor), oxygen consumption in IVF and SCNT blastocysts at Day 5 increased (112 � 18 and 51 � 44%, respectively) or decreased (50 � 20 and 21 � 32%, respectively) compared with those of nontreated embryos. Sensitivity to these reagents differed significantly (P &lt; 0.05) between IVF and SCNT, indicating that the SCNT blastocysts had a lower OXPHOS capacity than those from IVF. These results suggest that reprogramming for sustaining mitochondrial function during pre-implantation development may be required in miniature pig SCNT embryos.

310 COBALAMIN SUPPLEMENTATION DURING IN VITRO MATURATION IMPROVES PREIMPLANTATION DEVELOPMENT OF SHEEP EMBRYOS

2015 ◽  
Vol 27 (1) ◽  
pp. 244 ◽  
Author(s):  
F. Zacchini ◽  
P. Toschi ◽  
P. Loi ◽  
G. E. Ptak
Keyword(s):  
Blastocyst Stage ◽  
Developmental Competence ◽  
Pcr Analysis ◽  
Fisher Exact Test ◽  
Placental Development ◽  
Cleavage Rate ◽  
Fetal Survival ◽  
Qrt Pcr

Oocyte maturation process includes the establishment of proper epigenetics marks, fundamental to ensure successful pregnancy. Epigenetic maturation of the oocyte depends on one-carbon-metabolism (OCM), whose key elements (cobalamin, folate) are crucial cofactors for the transfer of methyl groups onto chromatin. Commercially available IVM-media only partially supports oocyte metabolic requirements, and thus may negatively affect epigenetic maturation. Of relevance, cobalamin, one of the OCM cofactors normally present in follicular fluid, is missing in IVM-media. We investigated if cobalamin supplementation of IVM media affects sheep oocyte developmental competence in term of subsequent embryo development, epigenetic pattern, and fetal survival. Briefly, sheep oocytes were isolated from ovaries and divided into 2 groups: an untreated control (in vitro CTR group) and oocytes in vitro matured in medium containing cobalamin at 200 p.m. (Cobalamin group). Following maturation, MII oocytes were in vitro fertilized and cultured until blastocyst stage. A cohort of blastocysts was surgically transferred to recipient ewes and then conceptuses were collected at 20 days of pregnancy. Naturally mated conceptuses were also collected (in vivo CTR group). In vitro-matured oocytes and -derived blastocysts were analysed (i) by immunofluorescence anti-5-methylcitydine and (ii) by qRT-PCR for the expression of a panel of genes (MATb, ACHY, CBS, MTHFR, DNMT1) involved in OCM pathway. Immunofluorescence results were analysed by Image J software. Decimal variables were analysed using the Mann-Whitney test, while variables were expressed as percentage with the Fisher exact test. Cobalamin exposure during IVM significantly increased (i) cleavage rate (cobalamin 130/220 v. in vitro CTR 134/191, P < 0.02) following in vitro fertilization and (ii) global DNA methylation in blastocyst-stage embryos (P < 0.05). Then, qRT-PCR analysis of a select panel of OCM genes following IVM supplemented with cobalamin revealed a downregulation of MATb, ACHY, and DNMT1 in cobalamin-treated oocytes v. in vitro CTR group (P < 0.05), while no differences were observed at blastocyst stage. Finally, we found that the survival rate at 20 days of pregnancy was comparable in in vitro-produced (IVP) embryos from cobalamin and in vitro CTR oocytes, but reduced compared to in vivo CTR (cobalamin 60%, in vitro CTR 72%, and in vivo CTR 100%). Altogether, our results showed that cobalamin supplementation in IVM medium positively affects competence of oocytes and methylation profile at the blastocyst stage, presumably through the OCM pathway. Moreover, postimplantation survival of IVP conceptus, derived from untreated and treated oocytes, was reduced compared to naturally mated ones. Further investigation will clarify whether cobalamin supplementation influences fetal and placental development of IVP conceptus.

35 Effect of Late Gestational Heat Stress on Placental Characteristics in Dairy Cattle

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 34-34
Author(s):  
Greer M Potadle ◽  
Geoff Dahl ◽  
Thaigo Fabris ◽  
Jennifer M Bundy ◽  
Howard Tyler
Keyword(s):  
Heat Stress ◽  
Surface Area ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Placental Weight ◽  
Late Gestation ◽  
Placental Development ◽  
Surface Areas ◽  
Humidity Index ◽  
Placental Efficiency

Abstract To determine the effects of late gestation heat stress on placental development, dairy cows were exposed to heat stress (HT, shade) or cooled (CL, shade, fans and soakers) during the final 46 d pre-calving on the University of Florida dairy facility (temperature-humidity index; THI &gt;68). We hypothesize heat stress (or lack of heat abatement) will reduce placental efficiency and in turn increase placental weight, surface area, and volume. At expulsion all placentae were collected and total placental weight was determined as well as individual cotyledonary weights, surface areas, and volume. In addition, the total number of total cotyledons was recorded and cotyledonary color and placental growth abnormalities (i.e. teratomas) were recorded and photographed. All data were analyzed using PROC MIXED in SAS. In addition, associations between parameters were determined by calculating Pearson Correlation Coefficients using SAS. Placentae from HT cows had a higher total placental weight, higher non-vascular membrane weight, higher total cotyledonary weight, higher total cotyledonary volume, and a higher incidence of teratomas than those from CL cows (P &lt; 0.05). HT cows also had placentae with a significantly greater average cotyledonary weight and volume (P &lt; 0.05). HT cows tended to have a greater incidence of color abnormalities in the placenta (P &lt; 0.075). In addition, HT cows had significantly lighter calves at birth (P &lt; 0.05). These data demonstrate that heat stress (or lack of heat abatement) impacts placental growth during the final stages of gestation, resulting in heavier placentae, an increase in cotyledonary weight and volume, but not an increase in the total number of cotyledons or total cotyledonary surface area. These placental alterations ultimately resulted in lighter calves at birth.

Cell-matrix interactions in the early mouse embryo

1992 ◽  
Vol 50 (1) ◽  
pp. 600-601
Author(s):  
A.E. Sutherland ◽  
P.G. Calarco ◽  
C.H. Damsky
Keyword(s):  
Mouse Embryo ◽  
Giant Cells ◽  
Blastocyst Stage ◽  
Integrin Subunit ◽  
Β1 Integrin ◽  
Cell Stage ◽  
Early Mouse Embryo ◽  
Migratory Activity ◽  
Early Mouse ◽  
Cell Matrix Interactions

Cell-extracellular matrix (ECM) interactions mediated by the integrin family of receptors are critical for morphogenesis and may also play a regulatory role in differentiation during early development. We have examined the onset of expression of individual integrin subunit proteins in the early mouse embryo, and their roles in early morphogenetic events. As detected by immunoprecipitation, the α6, αV, β1, and β3 subunits are detected as early as the 4-cell stage, α5 at the hatched blastocyst stage and αl and α3 following blastocyst attachment. We tested the role of these integrins in the attachment and migratory activity of two cell populations of the early mouse embryo: the trophoblast giant cells, which invade the uterine stroma and ultimately contribute to the chorio-allantoic placenta, and the parietal endoderm, which migrates over the inner surface of the trophoblast and ultimately forms Reichert's membrane and the parietal yolk sac. Experiments were done in serum-free medium on substrates coated with laminin (Ln) and fibronectin (Fn). Trophoblast outgrowth occurs on Ln and its E8 fragment (long arm), but not on the E1’ fragment (cross region) (Figs. 1, 2 ). This outgrowth is inhibited by anti-E8, anti-Ln, and by the anti-β1 family antiserum anti-ECMR, but not by anti-αV or the function-perturbing GoH3 antibody that recognizes the α6/β1 integrin, a major Ln (E8) receptor. This suggests that trophoblast outgrowth on Ln or E8 is mediated by a different β1 integrin such as α3/β1. Early stages of trophoblast outgrowth (up to 48 hours) on Fn are inhibited by anti-Fn and by function-perturbing anti-αV antibodies, whereas at later times outgrowth becomes insensitive to anti-αV but remains sensitive to the anti-β1 family antiserum anti-ECMr, indicating that trophoblast cells modulate their interaction with Fn during outgrowth. Trophoblast outgrowth on vitronectin (Vn) is sensitive to anti-αV antibodies throughout the 5-day period examined.

Maternal Marijuana Exposure, Feto-Placental Weight Ratio, and Placental Histology

2020 ◽  
Author(s):  
Torri D. Metz ◽  
Amanda A. Allshouse ◽  
Halit Pinar ◽  
Michael Varner ◽  
Marcela C. Smid ◽  
...  
Keyword(s):  
Tobacco Use ◽  
Fetal Growth ◽  
Statistical Significance ◽  
Weight Ratio ◽  
Marijuana Use ◽  
Placental Weight ◽  
Self Report ◽  
Serum Cotinine ◽  
Fetal Sex ◽  
Live Births

Objective Marijuana use is associated with placenta-mediated adverse pregnancy outcomes including fetal growth restriction, but the mechanism remains uncertain. The objective was to evaluate the association between maternal marijuana use and the feto-placental weight ratio (FPR). Secondarily, we aimed to compare placental histology of women who used marijuana to those who did not. Study Design This was a secondary analysis of singleton pregnancies enrolled in a multicenter and case–control stillbirth study. Prior marijuana use was detected by electronic medical record abstraction or cord homogenate positive for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid. Prior tobacco use was detected by self-report or presence of maternal serum cotinine. Stillbirths and live births were considered separately. The primary outcome was FPR. Association of marijuana use with FPR was estimated with multivariable linear modeling adjusted for fetal sex, preterm birth, and tobacco use. Comparisons between groups for placental histology were made using Chi-square and stratified by live birth and stillbirth, term and preterm deliveries, and fetal sex. Results Of 1,027 participants, 224 were stillbirths and 803 were live births. Overall, 41 (4%) women used marijuana during the pregnancy. The FPR ratio was lower among exposed offspring but reached statistical significance only for term stillbirths (mean 6.84 with marijuana use vs. mean 7.8 without use, p < 0.001). In multivariable modeling, marijuana use was not significantly associated with FPR (p = 0.09). There were no differences in histologic placental features among those with and without marijuana use overall or in stratified analyses. Conclusion Exposure to marijuana may not be associated with FPR. Similarly, there were no placental histologic features associated with marijuana exposure. Further study of the influence of maternal marijuana use on placental development and function is warranted to better understand the association between prenatal marijuana use and poor fetal growth. Key Points

scholarly journals Calcium-free vitrification reduces cryoprotectant-induced zona pellucida hardening and increases fertilization rates in mouse oocytes

Reproduction ◽  
2006 ◽  
Vol 131 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Mark G Larman ◽  
Courtney B Sheehan ◽  
David K Gardner
Keyword(s):  
Ethylene Glycol ◽  
Zona Pellucida ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Initial Increase ◽  
Cell Stage ◽  
Free Treatment ◽  
Zona Hardening ◽  
Free Media ◽  
Oocyte Freezing

Despite the success of embryo cyropreservation, routine oocyte freezing has proved elusive with only around 200 children born since the first reported birth in 1986. The reason for the poor efficiency is unclear, but evidence of zona pellucida hardening following oocyte freezing indicates that current protocols affect oocyte physiology. Here we report that two cryoprotectants commonly used in vitrification procedures, dimethyl sulfoxide (DMSO) and ethylene glycol, cause a large transient increase in intracellular calcium concentration in mouse metaphase II (MII) oocytes comparable to the initial increase triggered at fertilization. Removal of extracellular calcium from the medium failed to affect the response exacted by DMSO challenge, but significantly reduced the ethylene glycol-induced calcium increase. These results suggest that the source of the DMSO-induced calcium increase is solely from the internal calcium pool, as opposed to ethylene glycol that causes an influx of calcium across the plasma membrane from the external medium. By carrying out vitrification in calcium-free media, it was found that zona hardening is significantly reduced and subsequent fertilization and development to the two-cell stage significantly increased. Furthermore, such calcium-free treatment appears not to affect the embryo adversely, as shown by development rates to the blastocyst stage and cell number/allocation. Since zona hardening is one of the early activation events normally triggered by the sperm-induced calcium increases observed at fertilization, it is possible that other processes are negatively affected by the calcium rise caused by cryoprotectants used during oocyte freezing, which might explain the current poor efficiency of this technique.

Synthesis and phosphorylation of uvomorulin during mouse early development

Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 313-318 ◽  
Author(s):  
M. Sefton ◽  
M.H. Johnson ◽  
L. Clayton
Keyword(s):  
Cell Adhesion ◽  
Early Development ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Blastocyst Stage ◽  
Embryonic Stage ◽  
Cell Stage ◽  
Mouse Oocytes ◽  
Maternal Mrna ◽  
Embryonic Genome

The cell adhesion molecule, uvomorulin, is synthesised in both the 135 × 10(3) M(r) precursor and 120 × 10(3) M(r) mature forms on maternal mRNA templates in unfertilized and newly fertilized mouse oocytes. Synthesis on maternal message ceases during the 2-cell stage to resume later on mRNA encoded presumptively by the embryonic genome. Uvomorulin is detectable by immunoblotting at all stages upto the blastocyst stage, but shows variations in its total amount and processing with embryonic stage. Whilst only trace levels of phosphorylated uvomorulin are detectable in early and late 4-cell embryos, uvomorulin in 8-cell embryos is phosphorylated.

Sign in / Sign up

Export Citation Format

Share Document