HPRT activity in embryos of a South American opossum Monodelphis domestica

1994 ◽  
Vol 6 (4) ◽  
pp. 529 ◽  
Author(s):  
PG Johnston ◽  
D Dean ◽  
JL VandeBerg ◽  
ES Robinson
Keyword(s):  
X Chromosome ◽  
Blastocyst Stage ◽  
Monodelphis Domestica ◽  
X Inactivation ◽  
Hypoxanthine Phosphoribosyl Transferase ◽  
South American ◽  
Cell Stage ◽  
Phosphoribosyl Transferase ◽  
Stage Of Development ◽  
American Opossum

Marsupial females show preferential paternal X-inactivation. However, the time at which X-inactivation occurs in early development has not yet been determined. A double microassay which measures the activities of X-linked hypoxanthine phosphoribosyl transferase (HPRT) and the autosomally-coded adenine phosphoribosyl transferase (APRT) from the same sample was performed on a collection of embryos from a South American opossum Monodelphis domestica. The embryos ranged in age from the 2-cell stage to the bilaminar blastocyst stage. The results indicate that their embryonic HPRT and APRT are not expressed until just before the unilaminar blastocyst stage in M. domestica. This is at a later stage of development than that in the mouse where embryonic HPRT and APRT expression first occurs at the 4-8-cell stage. It is concluded that HPRT is an uniformative enzyme for assessing X chromosome activity in cleaving embryos of M. domestica. The widespread distribution of HPRT:APRT ratios after the unilaminar blastocyst stage also makes it difficult to draw conclusions about the state of X chromosome activity in early marsupial development.

X Chromosome Inactivation and Imprinting

1996 ◽  
Vol 45 (1-2) ◽  
pp. 85-85
Author(s):  
M.F. Lyon
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Blastocyst Stage ◽  
X Inactivation ◽  
Xist Gene ◽  
Paternal Allele ◽  
Xist Expression ◽  
Cell Stage ◽  
Reading Frame ◽  
Genetic Imprinting

In contrast to the random inactivation of either maternal or paternal X-chromosome in the somatic cells of eutherian mammals, in marsupials the paternal X-chromosome is preferentially inactivated in all cells. Similar exclusively paternal X-inactivation occurs in two extraembryonic cell lineages of mice and rats. Thus, genetic imprinting is an important feature of X-inactivation. In embryonic development the initiation of X-inactivation is thought to occur through the X-inactivation centre, located on the X-Chromosome, and thus imprinting probably acts through this centre. A candidate gene for a role in the inactivation centre is Xist (X inactive specific transcript) which is expressed only from the inactive X-Chromosome. The expression of Xist in the mouse embryo is appropriate for it to be a cause rather than a consequence of inactivation. It appears before inactivation, and only the paternal allele is expressed in the extraembryonic lineages. In the germ cells also changes in X-chromosome activity are accompanied by changes in Xist expression. Studies of methylation of the Xist gene have shown that in male tissues where Xist is not active it is fully methylated, whereas in the female the allele on the active X-chromosome only is methylated. In male germ cells, where Xist is expressed, it is demethylated and the demethylation persists in mature spermatozoa. Thus a methylation difference in germ cells could possibly be the imprint. In androgenotes, with paternally derived chromosomes, Xist is expressed at the 4-cell stage, whereas in gynogenotes and parthenogenotes expression does not appear until the blastocyst stage. Thus, Xist expression shows imprinting. When expression appears in parthenogenotes it is random, suggesting that the imprint has been lost. The Xist gene has no open reading frame and is thought to act through mRNA but its function is unknown.

scholarly journals EXPRESSION OF MATERNALLY AND EMBRYONICALLY DERIVED HYPOXANTHINE PHOSPHORIBOSYL TRANSFERASE (HPRT) ACTIVITY IN MOUSE EGGS AND EARLY EMBRYOS

Genetics ◽  
1983 ◽  
Vol 104 (4) ◽  
pp. 685-698
Author(s):  
Paul G Kratzer
Keyword(s):  
X Chromosome ◽  
Gene Dosage ◽  
Activity Level ◽  
Hypoxanthine Phosphoribosyl Transferase ◽  
Mouse Development ◽  
Cell Stage ◽  
Activity Increase ◽  
Phosphoribosyl Transferase ◽  
Early Embryos ◽  
Before And After

ABSTRACT X-chromosome activity in early mouse development has been studied by a gene dosage method that involves measuring the activity level of the X-linked enzyme hypoxanthine phosphoribosyl transferase (HPRT) in single eggs and embryos from XO females and from females heterozygous for In(X)1H, a paracentric inversion of the X chromosome. The HPRT activity in oocytes increased threefold over a 24-hr period beginning after ovulation. Afterward, the activity plateaued in unfertilized eggs but continued to increase for at least 66 hr in presumed OY embryos. Both before and after ovulation, the level of activity in unfertilized eggs from In(X)/X females was twice that from XO females, and the distributions of activity in eggs for both sets of females remained unimodal. Beginning with the two-cell stage, distributions of activity for embryos from In(X)/X females were trimodal, which is evidence for embryonic activity. It is proposed that activation of a maternal mRNA or proenzyme is responsible for the HPRT activity increase in oocytes and early embryos and is supplemented by dosage-dependent activity of the embryonic Hprt gene as early as the two-cell stage.

X-chromosome inactivation in XX androgenetic mouse embryos surviving implantation

Development ◽  
2000 ◽  
Vol 127 (19) ◽  
pp. 4137-4145 ◽  
Author(s):  
I. Okamoto ◽  
S. Tan ◽  
N. Takagi
Keyword(s):  
X Chromosome ◽  
Ectopic Expression ◽  
Blastocyst Stage ◽  
X Chromosome Inactivation ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
Current View ◽  
Replication Banding ◽  
Xist Rna ◽  
Morula Stage

Using genetic and cytogenetic markers, we assessed early development and X-chromosome inactivation (X-inactivation) in XX mouse androgenones produced by pronuclear transfer. Contrary to the current view, XX androgenones are capable of surviving to embryonic day 7.5, achieving basically random X-inactivation in all tissues including those derived from the trophectoderm and primitive endoderm that are characterized by paternal X-activation in fertilized embryos. This finding supports the hypothesis that in fertilized female embryos, the maternal X chromosome remains active until the blastocyst stage because of a rigid imprint that prevents inactivation, whereas the paternal X chromosome is preferentially inactivated in extra-embryonic tissues owing to lack of such imprint. In spite of random X-inactivation in XX androgenones, FISH analyses revealed expression of stable Xist RNA from every X chromosome in XX and XY androgenonetic embryos from the four-cell to morula stage. Although the occurrence of inappropriate X-inactivation was further suggested by the finding that Xist continues ectopic expression in a proportion of cells from XX and XY androgenones at the blastocyst and the early egg cylinder stage, a replication banding study failed to provide positive evidence for inappropriate X-inactivation at E6. 5.

Physical mapping of the IGF2 locus in the South American opossum Monodelphis domestica

2007 ◽  
Vol 116 (1-2) ◽  
pp. 130-131 ◽  
Author(s):  
B.R. Lawton ◽  
C. Obergfell ◽  
R.J. O’Neill ◽  
M.J. O’Neill
Keyword(s):  
Physical Mapping ◽  
Monodelphis Domestica ◽  
South American ◽  
The South ◽  
American Opossum

159 USE OF PHYTOHEMAGGLUTININ-L, AS AN AGGLUTINATOR AGENT, TO PRODUCE CHIMERAS OF IVF BOVINE EMBRYOS

2010 ◽  
Vol 22 (1) ◽  
pp. 238
Author(s):  
I. P. Emanuelli ◽  
B. F. Agostinho ◽  
M. P. M. Mancini ◽  
C. M. Barros ◽  
M. F. G. Nogueira
Keyword(s):  
Embryonic Stem ◽  
Blastocyst Stage ◽  
Bovine Embryos ◽  
Cell Stage ◽  
Exact Test ◽  
Fisher's Exact Test ◽  
Stage Of Development ◽  
Fisher’S Exact Test

Embryonic chimeras have been used as a tool to understand embryogenesis and organogenesis, as well as to prove, in vivo, the pluripotency of the embryonic stem cells. One of the techniques used to obtain embryonic chimeras is aggregation, which can be performed with intact or half-embryos and in different stages of the development, produced by in vivo or in vitro systems and in different wells. However, its efficiency tends to reduce when advanced stages, such as morulae and blastocysts, are used. The aim of this work was to evaluate the effect of the treatment with an agglutinating agent (phytohemagglutinin-L; PHA) in the percentage of chimeras produced with IVF bovine embryos. Bovine ovaries (from abattoir) were used to obtain 270 COC that were matured in drops (90 μL) of TCM-199 bicarbonate medium, supplemented with 10% of FCS, and incubated in vitro for 22 to 24 h. The fertilization occurred in TALP-IVF medium, and the COC were maintained in the incubator for 18 h. After fertilization, the presumptive zygotes were transferred to SOF culture medium to in vitro culture. In vitro maturation, fertilization, and culture were performed under 38.5°C, 5% CO2 in air and saturated humidity. The chimerism by aggregation was tested between 2 intact (zona-free) 8- to 16-cell stage embryos in the presence (G1, n = 16) or absence of PHA (G2, n = 14) and between one half-morula and one half-blastocyst with (G3, n = 15) or without PHA (G4, n = 12). The embryos in groups G1 and G3 were treated with PHA in a concentration of 500 μLg mL-1 for 3 min. After PHA treatment, the pairs of embryos were allocated in wells, under previously described culture conditions, until expanded blastocyst stage could be observed (Day 7 of culture). At 24 h of culture, embryonic aggregation pairs were first evaluated to detect only cohesive masses of cells. The results (chimerism rate) were 62.5%, 42.9%, 40.0%, and 25.0%, respectively, for groups G1, G2, G3, and G4. There were no significant differences neither among groups (chi-square, P = 0.252) nor between G1 and G2 (P = 0.464), G3, and G4 (P = 0.683; Fisher’s exact test). Main effects as use of PHA (G1 + G3 v. G2 + G4, P = 0.284) and stage of embryos (G1 + G2 v. G3 + G4, P = 0.183; Fisher’s exact test) were not statistically significant. However, when all groups were compared, the power of the performed test (0.354) was below the desired power of 0.800 (i.e. one must be cautious in over-interpreting the lack of difference among them). In the conditions of this study, it was concluded that the treatment with PHA did not increase the rate of aggregation in the embryonic chimera production, even for half-embryos in advanced stage of development (morulae and blastocysts). Granted by FAPESP, Brazil: 06/06491-2 and 07/07705-9 (MFGN) and 07/04291-9 (MPMM).

123 CHANGES IN EXPRESSION OF GENES ASSOCIATED WITH GENETIC VARIATION IN PRE-IMPLANTATION DEVELOPMENT OF THE BOVINE EMBRYO

2014 ◽  
Vol 26 (1) ◽  
pp. 175
Author(s):  
M. S. Ortega ◽  
J. B. Cole ◽  
T. S. Sonstegard ◽  
P. J. Hansen
Keyword(s):  
Genetic Variation ◽  
Intracellular Transport ◽  
Blastocyst Stage ◽  
Acid Oxidation ◽  
Lethal Gene ◽  
Bovine Embryo ◽  
Cell Stage ◽  
Glycoprotein Synthesis ◽  
Stage Of Development

The objective was to identify patterns of expression during the pre-implantation period of several genes associated with genetic variation in fertility (CWC15) or development to the blastocyst stage (C1QB, MON1B, PARM1, PCCB, PMM2, TBC1D24, and WBP1). These genes are involved in cellular processes such as mRNA splicing, immune protection, fatty acid oxidation, resistance to apoptosis, glycoprotein synthesis, and intracellular transport. Embryos were produced in vitro from slaughterhouse oocytes and semen using a mix of Bos taurus and Bos indicus cows and bulls. Pools of 40 matured oocytes or embryos at the 2-cell [27–31 h post-insemination (hpi)], 3- to 4-cell (46–52 hpi), 5- to 8-cell (49–59 hpi), 9- to 16-cell (72–75 hpi), morula (120–123 hpi), and blastocyst (168–171 hpi) stages were collected. The RNA was purified and synthesised into cDNA for real-time qPCR analysis. The YWHAZ, GAPDH, and SDHA were used as steady-state controls of expression. A total of 5 pools were analysed for each of the 6 stages. The C1QB was not detected at any stage; however, transcript amounts for the other genes were affected by stage of development (P < 0.05). The WBP1 remained low from the oocyte to the 5- to 8-cell stage (fold-change relative to matured oocytes: 1.0 ± 0.2 v. 1.4 ± 0.2), increased at the 9- to 16-cell stage (14.8 ± 0.2), and decreased to the blastocyst stage (7.1 ± 0.2). The expression pattern of PARM1 was similar, with greatest expression at the 9- to 16-cell stage. In contrast, expression of PMM2 and TBC1D24 was highest at the 2-cell stage and decreased at the morula and blastocyst stages. Expression of CWC15, MON1B, and PCCB decreased steadily from the oocyte to the blastocyst stage. Given that the major round of embryonic genome activation occurs at the 8- to 16-cell stage, it is possible that PARM1 and WBP1 play important roles around this time. The PMM2 and TBC1D24 may represent genes activated before the 8- to 16-cell stage. The CWC15 has been identified as a lethal gene; results suggest lethality occurs after the blastocyst stage. Further research will clarify the role and importance of these genes in the early development of the bovine embryo. The authors acknowledge support from AFRI Grant No. 2013–68004–20365 from USDA NIFA.

Allele-specific expression analysis reveals conserved and unique features of preimplantation development in equine ICSI embryos

2021 ◽  
Author(s):  
D E Goszczynski ◽  
P S Tinetti ◽  
Y H Choi ◽  
P J Ross ◽  
K Hinrichs
Keyword(s):  
Gene Expression ◽  
Early Development ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Blastocyst Stage ◽  
X Chromosome Inactivation ◽  
Specific Gene ◽  
Cell Stage ◽  
Specific Gene Expression ◽  
Genome Activation

Abstract Embryonic genome activation and dosage compensation are major genetic events in early development. Combined analysis of single embryo RNA-seq data and parental genome sequencing was used to evaluate parental contributions to early development and investigate X-chromosome dynamics. In addition, we evaluated dimorphism in gene expression between male and female embryos. Evaluation of parent-specific gene expression revealed a minor increase in paternal expression at the 4-cell stage that increased at the 8-cell stage. We also detected eight genes with allelic expression bias that may have an important role in early development, notably NANOGNB. The main actor in X-chromosome inactivation, XIST, was significantly upregulated at the 8-cell, morula, and blastocyst stages in female embryos, with high expression at the latter. Sexual dimorphism in gene expression was identified at all stages, with strong representation of the X-chromosome in females from the 16-cell to the blastocyst stage. Female embryos showed biparental X-chromosome expression at all stages after the 4-cell stage, demonstrating the absence of imprinted X-inactivation at the embryo level. The analysis of gene dosage showed incomplete dosage compensation (0.5 &lt; X:A &lt; 1) in MII oocytes and embryos up to the 4-cell stage, an increase of the X:A ratio at the 16-cell and morula stages after genome activation, and a decrease of the X:A ratio at the blastocyst stage, which might be associated with the beginning of X-chromosome inactivation. This study represents the first critical analysis of parent- and sex-specific gene expression in early equine embryos produced in vitro.

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