190 EXPRESSION OF GENES ASSOCIATED WITH WINGLESS-RELATED MOUSE MAMMARY TUMOUR VIRUS SIGNALING IN THE PRE-IMPLANTATION BOVINE EMBRYO

2015 ◽  
Vol 27 (1) ◽  
pp. 186
Author(s):  
P. Tribulo ◽  
J. I. Moss ◽  
P. J. Hansen

Wingless-related mouse mammary tumour virus (WNT) signalling participates in early embryonic development to maintain pluripotency, controls cell–cell communication, and modulates cell polarization and migration. To gain an understanding of the regulation of WNT signalling during embryonic development, expression patterns of a variety of molecules involved in WNT signal transduction were evaluated. Specific genes were DKK1, an endogenous inhibitor of canonical WNT signalling, the WNT co-receptors LRP5 and LRP6, WNT-responsive transcription factors, LEF1 and TCF7, and two repressors of WNT-regulated genes, the bovine orthologue of GROUCHO (LOC505120) and AES. Embryos were produced in vitro from oocytes obtained from ovaries collected at a local abattoir. Following oocyte maturation, fertilization was performed with sperm pooled from three randomly selected bulls; a different pool of bulls was used for each replicate. Groups of 30 matured oocytes or embryos at the 2-cell [28–32 h post-insemination (hpi)], 3–4 cell (44–48 hpi), 5–8 cell (50–55 hpi), 9–16 cell (72–75 hpi), morula (120–123 hpi), and blastocyst (168–171 hpi) stages were collected. The zona pellucida was removed with proteinase, RNA was purified, cDNA synthesised using random hexamer primers and real-time qPCR performed. Data analysed were ΔCT values, which were calculated by subtracting the CT value of the geometric mean of the three housekeeping genes (GAPDH, YWHAZ, and SDHA) from the CT value of the sample. The relative transcript abundance was calculated as the 2ΔCT. Data were analysed by least-squares ANOVA using the Proc GLM procedure of SAS (SAS Institute Inc., Cary, NC, USA). A total of 5 replicates were analysed for each developmental stage. Results show significant effects of stage of development for each gene that ranged from P = 0.004 for LRP5 to P ≤ 0.0001 for AES, DKK1, LEF, LOC505120, LRP6, and TCF7. In all cases, expression declined as development advanced. Except for AES, lowest expression occurred at the blastocyst stage. Lowest expression for AES was at the morula stage; expression remained low at the blastocyst stage. For two genes, DKK1 and LEF1, there was no detectable expression at the blastocyst stage. The timing of decline in expression varied between genes, first occurring at the 9–16-cell stage (AES, LEF1, and LOC505120) or morula stage (DKK1, LRP5, LRP6, or TCF7). For DKK1, LEF1, and LRP6, there was also a slight increase in expression from the oocyte to two-cell stage. Results suggest that canonical WNT signalling is reduced at the morula and blastocyst stages relative to earlier stages in development. Research was supported by USDA-NIFA 2011-67015-30688.

Reproduction ◽  
2012 ◽  
Vol 143 (5) ◽  
pp. 625-636 ◽  
Author(s):  
Chang-Gi Hur ◽  
Eun-Jin Kim ◽  
Seong-Keun Cho ◽  
Young-Woo Cho ◽  
Sook-Young Yoon ◽  
...  

Numerous studies have suggested that K+ channels regulate a wide range of physiological processes in mammalian cells. However, little is known about the specific function of K+ channels in germ cells. In this study, mouse zygotes were cultured in a medium containing K+ channel blockers to identify the functional role of K+ channels in mouse embryonic development. Voltage-dependent K+ channel blockers, such as tetraethylammonium and BaCl2, had no effect on embryonic development to the blastocyst stage, whereas K2P channel blockers, such as quinine, selective serotonin reuptake inhibitors (fluoxetine, paroxetine, and citalopram), gadolinium trichloride, anandamide, ruthenium red, and zinc chloride, significantly decreased blastocyst formation (P<0.05). RT-PCR data showed that members of the K2P channel family, specifically KCNK2, KCNK10, KCNK4, KCNK3, and KCNK9, were expressed in mouse oocytes and embryos. In addition, their mRNA expression levels, except Kcnk3, were up-regulated by above ninefold in morula-stage embryos compared with 2-cell stage embryos (2-cells). Immunocytochemical data showed that KCNK2, KCNK10, KCNK4, KCNK3, and KCNK9 channel proteins were expressed in the membrane of oocytes, 2-cells, and blastocysts. Each siRNA injection targeted at Kcnk2, Kcnk10, Kcnk4, Kcnk3, and Kcnk9 significantly decreased blastocyst formation by ∼38% compared with scrambled siRNA injection (P<0.05). The blockade of K2P channels acidified the intracellular pH and depolarized the membrane potential. These results suggest that K2P channels could improve mouse embryonic development through the modulation of gating by activators.


2010 ◽  
Vol 22 (1) ◽  
pp. 231
Author(s):  
C. Y. Choe ◽  
S. R. Cho ◽  
J. K. Son ◽  
S. H. Choi ◽  
C. Y. Cho ◽  
...  

Oxygen consumption has been regarded as a useful indicator for assessment of mammalian embryo quality. This study was carried out to identify whether oxygen consumption rates measured in bovine embryos using SECM can be used as a standard criteria to evaluate bovine embryo quality. Oxygen consumption of bovine embryos at various developmental stages was measured and analyzed using SECM and ANOVA analysis, respectively. We found that the oxygen consumption significantly increased in blastocyst-stage embryos compared to other stage embryos (from 2-cell stage to morula stage), indicating that oxygen consumption reflects the cell number (5.2-7.6 × 1014 mol-1 s-1 v. 1.2-2.4 × 1014 mol-1 s-1, P < 0.05). There was no significant difference between 2-cell-stage embryos and 8-cell-stage embryos. In the morula-stage embryos, the oxygen consumption of in vivo derived embryos was significantly higher than that of in vitro produced embryos (4.0 × 1014 mol-1 s-1 v. 2.4 × 1014 mol-1 s-1, P < 0.05). However, there was no significant difference in consumption of oxygen by in vivo and in vitro derived bovine blastocyst-stage embryos (P > 0.05). Good-quality embryos with grade 1 or 2 showed significantly higher oxygen consumption than grade 3 or 4 embryos. These results showed that SECM could measure oxygen consumption in bovine embryos and the oxygen consumption could reflect embryonic development stage and embryo quality.


Reproduction ◽  
2017 ◽  
Vol 153 (4) ◽  
pp. 405-419 ◽  
Author(s):  
Paula Tribulo ◽  
James I Moss ◽  
Manabu Ozawa ◽  
Zongliang Jiang ◽  
Xiuchun (Cindy) Tian ◽  
...  

The bovine was used to examine the potential for WNT signaling to affect the preimplantation embryo. Expression of seven key genes involved in canonical WNT signaling declined to a nadir at the morula or blastocyst stage. Expression of 80 genes associated with WNT signaling in the morula and inner cell mass (ICM) and trophectoderm (TE) of the blastocyst was also evaluated. Many genes associated with WNT signaling were characterized by low transcript abundance. Seven genes were different between ICM and TE, and all of them were overexpressed in TE as compared to ICM, including WNT6, FZD1, FZD7, LRP6, PORCN, APC and SFRP1. Immunoreactive CTNNB1 was localized primarily to the plasma membrane at all stages examined from the 2-cell to blastocyst stages of development. Strikingly, neither CTNNB1 nor non-phospho (i.e., active) CTNNB1 was observed in the nucleus of blastomeres at any stage of development even after the addition of WNT activators to culture. In contrast, CTNNB1 associated with the plasma membrane was increased by activators of WNT signaling. The planar cell polarity pathway (PCP) could be activated in the embryo as indicated by an experiment demonstrating an increase in phospho-JNK in the nucleus of blastocysts treated with the non-canonical WNT11. Furthermore, WNT11 improved development to the blastocyst stage. In conclusion, canonical WNT signaling is attenuated in the preimplantation bovine embryo but WNT can activate the PCP component JNK. Thus, regulation of embryonic development by WNT is likely to involve activation of pathways independent of nuclear actions of CTNNB1.


2005 ◽  
Vol 17 (2) ◽  
pp. 216
Author(s):  
P. Booth ◽  
T. Watson ◽  
H. Leese

Pre-implantation embryos can produce and consume amino acids in a manner dependent upon stage of embryonic development (Partridge and Leese 1996 Reprod. Fert. Dev. 8, 945) that may also be predictive of subsequent viability (Houghton et al. 2002 Hum. Reprod. 17, 999). To examine these relationships in the pig, the appearance or depletion of 18 amino acids from a presumptive near-physiological mixture was determined by HPLC in porcine in vitro-produced embryos from the zygote to the blastocyst stage. Cumulus oocyte complexes derived from slaughterhouse prepubertal pig ovaries were matured for 40 h in modified TCM-199 before being fertilized (Day 0) with frozen thawed semen in tris-based medium. After 6 h, presumptive zygotes were denuded and cultured in groups of 20 in NCSU medium modified to contain a physiological mixture of 18 amino acids including 0.1 mM glutamine (NCSUaa). Groups of 2–10 embryos (dependent on stage) were removed on Day 0 (1 cell), Day 1 (2- and 4-cell), Day 4 (compact morula), and Day 6 (blastocyst) and placed in 4 μL NCSUaa for 24 h. After incubation, the embryos were removed and the medium analyzed by HPLC. Each stage was replicated 3–9 times. Since amino acid profiles of 2- and 4-cell embryos were not different, data were combined. Overall, arginine (1.19 ± 0.33), glutamine (0.78 ± 0.34) and threonine (0.05 ± 0.04) were significantly (P < 0.01) depleted from the medium whereas alanine (0.21 ± 0.1), glycine (0.20 ± 0.06), asparagine (0.13 ± 0.5), lysine (0.1 ± 0.03), isoleucine (0.08 ± 0.01), valine (0.05 ± 0.01), leucine (0.04 ± 0.02), phenylalanine (0.03 ± 0.01), and histidine (0.02 ± 0.04) significantly (P < 0.05) accumulated (mean of the 4 sampling timepoints; all values pmol/embryo/h ± SEM). The difference between amino acid accumulation and depletion (balance) was approximately equivalent between Day 0 and the morula stage although turnover (sum of depletion and accumulation) steadily decreased during this period from 3.1 on Day 0 to 1.35 pmol/embryo/h at the morula stage. However, at the blastocyst stage, turnover and balance increased to 6.32 and 2.42 pmol/embryo/h, respectively, i.e. net appearance occurred. Notable changes in amino acid profile during development included decreases in accumulation of asparagine, glutamate, and glycine in the medium and the depletion of glutamine over Days 0, 1, and 4, followed by reversal of these trends by Day 6. These data suggest that pig embryos can alter the accumulation and depletion rates of amino acids in a manner that is dependent on the specific amino acid and the stage of embryonic development. This work was supported by BBSRC.


2007 ◽  
Vol 19 (1) ◽  
pp. 214 ◽  
Author(s):  
S. Yavin ◽  
A. Aroyo ◽  
Z. Roth ◽  
A. Arav

Embryonic development is a dynamic process in which embryo morphology may change immensely within several hours. Therefore, identifying and selecting embryos with the highest probability of developing and achieving a pregnancy is a major challenge. The timing of embryonic cleavage may serve as an additional indicator for the identification of quality embryos. The aim of this study was to characterize the cleavage timing of mouse embryos and to identify the stage that is most indicative of blastocyst formation. Mated mice (CB6F1) were sacrificed 20 h after hCG administration; putative zygotes were recovered and cultured (50 embryos in each 20-µL drop of M16) in a time-lapse system (EmbryoGuard; IMT, Ltd., Ness-Ziona, Israel) inside the incubator. The time-lapse system was programmed to take photos at half-hour intervals such that culture dishes were not removed from the incubator. The ‘shortest half’ statistical procedure of JMPIN (SAS Institute, Inc., Cary, NC, USA) was utilized to evaluate the period during which at least 50% of the embryonic population cleaves within the shortest time frame. Captured images made it possible to search along the time axis for the densest 50% of cleavage observations. Developing embryos were categorized into 3 groups according to the time of cleavage after hCG administration: before, during, and after the ‘shortest half’ for each developmental stage. Two hundred thirty putative zygotes cleaved and created 2-cell-stage embryos, of which 55 arrested at various stages and 175 progressed to the blastocyst stage. During embryonic development, cleavage timing appeared to become less uniform and the ‘shortest half’ became longer for each successive cell division: Whereas the shortest period in which 50% of the 2-cell-stage embryos cleaved was a 2-h interval, cleavage into the 4-cell, 8-cell, and blastocyst stages took 2.5, 3.5, and 5 h, respectively. The ‘short half’ for the first cleavage appears to be a predictive time frame for subsequent embryonic development, because cleavage was closely synchronized with 80% of the embryos developing to the blastocyst stage. Note that only a small number of embryos were actually cleaving early, while the ‘shortest half’ consisted of 50% of the embryonic population. Moreover, late-cleaving embryos in the 2-cell stage expressed inferior developmental potential relative to those that cleaved within the ‘shortest half’ (see Table 1). In summary, 2-cell-stage embryos that cleaved within the ‘shortest half’ seemed to be better synchronized and consequently more competent than the rest of the embryonic population. Embryonic cleavage timing using the ‘shortest half’ parameter can be considered a biological indicator of embryo potential. It may be useful as an additional tool for selecting embryos for transfer and cryopreservation. Table 1. Cleavage timing distribution into the 2-cell stage according to the shortest half


2013 ◽  
Vol 25 (1) ◽  
pp. 255
Author(s):  
C. Sauvegarde ◽  
D. Paul ◽  
R. Rezsohazy ◽  
I. Donnay

Hox genes encode for homeodomain transcription factors well known to be involved in developmental control after gastrulation. However, the expression of some of these genes has been detected during oocyte maturation and early embryo development. An interesting expression profile has been obtained for HOXB9 in the bovine (Paul et al. 2011 Mol. Reprod. Dev. 78, 436): its relative expression increases between the immature oocyte and the zygote, further increases at the 5- to 8-cell stage to peak at the morula stage before decreasing at the blastocyst stage. The main objective of this work is to establish the HOXB9 protein profile from the immature oocyte to the blastocyst in the bovine. Bovine embryos were produced in vitro from immature oocytes obtained from slaughterhouse ovaries. Embryos were collected at the following stages: immature oocyte, mature oocyte, zygote (18 h post-insemination, hpi), 2-cell (26 hpi), 5 to 8 cell (48 hpi), 9 to 16 cell (96 hpi), morula (120 hpi), and blastocyst (180 hpi). The presence and distribution of HOXB9 proteins were detected by whole-mount immunofluorescence followed by confocal microscopy using an anti-human HOXB9 polyclonal antibody directed against a sequence showing 100% homology with the bovine protein. Its specificity to the bovine protein was controlled by Western blot on total protein extract from the bovine uterus and revealed, among a few bands of weak intensities, 2 bands of high intensity corresponding to the expected size. Oocytes or embryos were fixed and incubated overnight with rabbit anti-HOXB9 (Sigma, St. Louis, MO, USA) and mouse anti-E-cadherin (BD Biosciences, Franklin Lakes, NJ, USA) primary antibodies and then for 1 h with goat anti-rabbit Alexafluor 555 conjugated (Cell Signaling Technology, Beverly, MA, USA) and goat anti-mouse FITC-conjugated (Santa Cruz Biotechnology Inc., Santa Cruz, CA, USA) secondary antibodies. Embryos were then mounted in Vectashield containing DAPI. HOXB9 is detected from the immature oocyte to the blastocyst stage. At the immature oocyte stage, it is mainly localised in the germinal vesicle with a weak signal in the cytoplasm. At the mature oocyte stage, HOXB9 labelling is present in the cytoplasm. At the zygote stage, a stronger immunoreactivity is observed in the pronuclei than in the cytoplasm. From the 2-cell stage to the morula stage, the presence of HOXB9 is also more important in the nuclei than in the cytoplasm. HOXB9 is also observed at the blastocyst stage where it is localised in the nuclei of the trophectoderm cells, whereas an inconstant or weaker labelling is observed in the inner cell mass cells. In conclusion, we have shown for the first time the presence of the HOXB9 protein throughout early bovine embryo development. The results obtained suggest the presence of the maternal HOXB9 protein because it is already detected before the maternal to embryonic transition that occurs during the fourth cell cycle in the bovine. Finally, the pattern obtained at the blastocyst stage suggests a differential role of HOXB9 in the inner cell mass and trophectoderm cells. C. Sauvegarde holds a FRIA PhD grant from the Fonds National de la Recherche Scientifique (Belgium).


2015 ◽  
Vol 27 (1) ◽  
pp. 188
Author(s):  
M. D. Snyder ◽  
J. H. Pryor ◽  
K. J. Veazey ◽  
M. D. Peoples ◽  
G. L. Williamson ◽  
...  

Organization of chromatin structure by the combinatorial patterns of DNA methylation and post-translational histone modification is essential for the establishment and maintenance of proper transcriptional programs that result in the coordination of embryonic development. We previously observed that suppression of transcripts encoding SET domain, bifurcated 1 (SETDB1) using small interfering RNAs (siRNA) is embryonic lethal, with SETDB1-suppressed embryos (n = 361) arresting immediately before the blastocyst stage (blastocyst rate: Control 44.9 ± 4.9% and NULL injected 25.7 ± 6.0%). Studies in rodents indicate SETDB1 is a crucial regulator of transposable elements and that the precise epigenetic regulation of these elements is a key aspect of transcriptional programs controlling pluripotency and placentation. To better characterise the molecular basis of the observed mortality, we analysed expression of the bovine Long Interspersed Nuclear Element 1 family (LINE1) of transposable elements via quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR). Mature bovine oocytes were obtained from a commercial supplier (De Soto Biosciences, Seymour, TN, USA) and IVF performed by standard laboratory protocol. Eighteen hours after IVF, cumulus cells were removed and presumptive zygotes divided into 3 different treatment groups: non-injected control (CNTL), non-targeting siRNA injected control (siNULL), and zygotes injected with siRNAs targeting SETDB1 (siSETDB1). Each embryo was injected with ~100 pL of siRNAs (10 µM) in fluorescent dextran solution. All zygotes were verified as injected by fluorescent microscopy and then cultured in Bovine Evolve (Zenith Biotech, Guilford, CT, USA) medium supplemented with 4 mg mL of BSA (Probumin, EMD Millipore, Darmstadt, Germany). Groups of embryos (15–20) from each treatment were lysed at the 4-cell, 8-cell, and morula stages, RNA extracted, and analysed by RT-qPCR using GAPDH and YWHAZ as reference genes. A two-way ANOVA and a Student's t-test were used to analyse the results from the RT-qPCR. As expected, siSETDB1-injected morulae displayed dramatic reduction in the level of Setdb1 transcripts as compared to siNULL control (96%; P < 0.05). Preliminary analysis of LINE1 transcripts at the morula stage indicated siSETDB1-injected embryos displayed a 75% reduction compared to the siNULL. Whether alteration in LINE1 regulation contributes to the developmental arrest and embryonic mortality of siSETDB1-injected embryos is under investigation.


Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1016 ◽  
Author(s):  
Bo Yu ◽  
Helena T. A. van Tol ◽  
Tom A.E. Stout ◽  
Bernard A. J. Roelen

X-chromosome inactivation (XCI) is a developmental process that aims to equalize the dosage of X-linked gene products between XY males and XX females in eutherian mammals. In female mouse embryos, paternal XCI is initiated at the 4-cell stage; however, the X chromosome is reactivated in the inner cell mass cells of blastocysts, and random XCI is subsequently initiated in epiblast cells. However, recent findings show that the patterns of XCI are not conserved among mammals. In this study, we used quantitative RT-PCR and RNA in situ hybridization combined with immunofluorescence to investigate the pattern of XCI during bovine embryo development. Expression of XIST (X-inactive specific transcript) RNA was significantly upregulated at the morula stage. For the first time, we demonstrate that XIST accumulation in bovine embryos starts in nuclei of female morulae, but its colocalization with histone H3 lysine 27 trimethylation was first detected in day 7 blastocysts. Both in the inner cell mass and in putative epiblast precursors, we observed a proportion of cells with XIST RNA and H3K27me3 colocalization. Surprisingly, the onset of XCI did not lead to a global downregulation of X-linked genes, even in day 9 blastocysts. Together, our findings confirm that diverse patterns of XCI initiation exist among developing mammalian embryos.


Zygote ◽  
2009 ◽  
Vol 18 (2) ◽  
pp. 121-129 ◽  
Author(s):  
A.T. Palasz ◽  
P. Beltrán Breña ◽  
J. De la Fuente ◽  
A. Gutiérrez-Adán

SummaryThe effect of bovine embryo culture on a flat surface, (without a surface-active compound) on the level of mRNA expression of hyaluronan (HA) synthases (Has1, Has2 and Has3), Ha receptors RHAMM and C44 receptors was evaluated by mitochondrial DNA concentration andin vitrodevelopment. Cultures were evaluated up to 96 h post-insemination (hpi) using SOFaa medium. Of the three Has isoforms, Has2 expression only increased in the bovine serum albumin (BSA)-only supplemented groups regardless of time of BSA addition. Expression of RHAMM receptors was highly dependent on the addition of HA, irrespective of the presence of BSA in the medium. In contrast, expression of the CD44 receptor gene was not affected by any treatment. The cleavage rates and number of embryos that developed to ≤8-cell stage by day 4 were not affected by lack of BSA in the medium, but increased numbers of blastocysts developed in medium supplemented with BSA from days 1 or 4 with or without HA than in medium that had HA only. Addition of both HA and BSA at day 4 increased mtDNA copy numbers at the blastocyst stage. Data suggest that the addition of BSA and/or HA at 96 hpi increased expression ofRHAMMandHas2genes, but notCD44,Has1orHas3genes. Higher expression levels of Has2 than Has1 and the three isoforms indicate that high- rather than low-molecular-weight HA should be used for preimplantation bovine embryo culture.


2016 ◽  
Vol 28 (4) ◽  
pp. 482 ◽  
Author(s):  
Qi-En Yang ◽  
Manabu Ozawa ◽  
Kun Zhang ◽  
Sally E. Johnson ◽  
Alan D. Ealy

Protein kinase C (PKC) delta (PRKCD) is a member of the novel PKC subfamily that regulates gene expression in bovine trophoblast cells. Additional functions for PRKCD in early embryonic development in cattle have not been fully explored. The objectives of this study were to describe the expression profile of PRKCD mRNA in bovine embryos and to examine its biological roles during bovine embryo development. Both PRKCD mRNA and protein are present throughout early embryo development and increases in mRNA abundance are evident at morula and blastocyst stages. Phosphorylation patterns are consistent with detection of enzymatically active PRKCD in bovine embryos. Exposure to a pharmacological inhibitor (rottlerin) during early embryonic development prevented development beyond the eight- to 16-cell stage. Treatment at or after the 16-cell stage reduced blastocyst development rates, total blastomere numbers and inner cell mass-to-trophoblast cell ratio. Exposure to the inhibitor also decreased basal interferon tau (IFNT) transcript abundance and abolished fibroblast growth factor-2 induction of IFNT expression. Furthermore, trophoblast adhesion and proliferation was compromised in hatched blastocysts. These observations provide novel insights into PRKCD mRNA expression profiles in bovine embryos and provide evidence for PRKCD-dependent regulation of embryonic development, gene expression and post-hatching events.


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