Biol Reprod
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

BOR - Papers in Press, published online ahead of print November 10, 2004.
Biol Reprod 2004, 10.1095/biolreprod.104.035444
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
72/3/612    most recent
biolreprod.104.035444v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.
Agricola
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.
BIOLOGY OF REPRODUCTION 72, 612–618 (2005)
DOI: 10.1095/biolreprod.104.035444
© 2005 by the Society for the Study of Reproduction, Inc.

Maternal Factors Controlling Blastomere Fragmentation in Early Mouse Embryos1

Zhiming Han4, Young Gie Chung3,4, Shaorong Gao4, and Keith E. Latham2,4,5

The Fels Institute for Cancer Research and Molecular Biology4 Department of Biochemistry,5 Temple University School of Medicine, Philadelphia, Pennsylvania 19140


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Interactions between sperm and egg are required to maintain embryo viability and cellular integrity. Differential transcriptional activities and epigenetic differences that include genomic imprinting provide mechanisms by which complementary parental genome functions support early embryogenesis. We previously showed that cytofragmentation can be influenced by the specific combination of maternal and paternal genotypes. Using maternal pronuclear transfer in mouse embryos, we examined the cellular basis for the maternal genotype effect. We found that the maternal genotype effect is predominantly controlled by the maternal pronucleus, with a lesser role played by the ooplasm. This effect of the maternal pronucleus is sensitive to {alpha}-amanitin treatment. The effect of the maternal component of the embryonic genome on cytofragmentation constitutes the earliest known effect of the embryonic genome on mammalian embryo phenotype. The results also indicate that clinical procedures seeking to define or manipulate oocyte quality in humans should take into account early effects of the embryonic genome, particularly the maternal genome.

apoptosis, cytofragmentation, embryo, gene regulation, maternal effect, oocyte


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Fertilization unites two gametes, each with dramatically different cellular and molecular characteristics. Both gametes contribute a haploid complement of DNA, along with other gamete-specific nuclear and cytoplasmic factors that may support development, as evidenced by known maternal and paternal effect mutations in a variety of organisms [1– 3]. Thus, cooperation between paternally and maternally derived factors may be a common feature among diverse species. The degree of this cooperation likely varies among taxa. Among mammals, parent-of-origin-specific epigenetic modifications (e.g., genomic imprinting) provide one basis for cooperation.

Under the control of ooplasmic factors, the sperm and egg genomes undergo an extensive series of modifications that collectively transform them into a newly formed embryonic genome that is able to initiate its programmed journey along the path leading to the formation of a new individual. This remarkable ability of the oocyte to direct this process likely constitutes the basis for successful cloning by nuclear transfer. Creating the embryonic genome requires the remodeling of chromatin to establish the capacity for transcriptional control [4, 5]. Chromatin remodeling is especially profound for the paternal genome, as the ooplasm mediates removal of protamines and their replacement with histones. Chromatin remodeling is followed by the acquisition of the ability of the ooplasm to support gene transcription, and ultimately, a major transcriptional activation event [4, 5]. During the critical time period preceding the major genome activation event, the metabolic and homeostatic functions of the early embryo are likewise largely directed by maternally inherited ooplasmic proteins, mRNAs, and other macromolecules. So pervasive is the ooplasm in controlling early embryogenesis that gene transcription before the major genome activation event is often perceived to be of little significance in mammalian embryos.

An increasing body of studies, however, indicates that a significant amount of gene transcription occurs well before the major genome activation event in most species [5]. Curiously, no functional role has yet been established for this early transcription. It has also become clear that the two parental genomes display differences in transcriptional activity before the major genome activation event in mice [6, 7]. The two genomes also display distinct molecular properties, including genomic imprinting and other epigenetic modifications [8–10]. Early gene transcription, coupled with early differences in pronuclear function, thus establish a possible basis for distinct but complementary effects of the two parental genomes on early embryo phenotype.

One critical, early function for the parental genomes may be to inhibit cell death or maintain blastomere integrity in the embryo. As either gamete in the absence of fertilization would be doomed to degenerate, an obligate consequence of fertilization is the suppression of pathways leading to cell death or degeneration. Under some circumstances, this suppression appears incomplete, leading to apoptotic-like events in the early embryo. These events include cytoplasmic fragmentation or blebbing, DNA fragmentation, and other changes often associated with cellular apoptosis [11, 12]. Cytoplasmic fragmentation can reduce the number of oocytes and embryos available for assisted reproduction protocols in humans. It may also reduce blastomere viability by selectively removing membrane-associated or cortical factors, such as growth factor receptors [12]. Higher pregnancy rates have been reported for human embryos with no fragmentation, or embryos judged to be of higher quality based in part on the degree of cytofragmentation [13, 14]. Other studies, however, found no such correlation [15], or found that certain spatial patterns of cytofragmentation correlated with reduced embryo viability, whereas other patterns of fragmentation did not [12, 16, 17]. Factors that increase the incidence of cytofragmentation can also decrease pregnancy rates [18], while culture conditions that reduce fragmentation are associated with improved blastocyst development [19]. Cytofragmentation in human embryos can be associated with expression of proapoptotic genes [20]. In mouse embryos, apoptosis and cytofragmentation are most commonly observed at the blastocyst stage [21, 22] and are associated with a variety of factors, including oxidative stress, diabetes, and specific gene mutations [22–26]. Cytofragmentation also occurs at the two-cell stage in the mouse [27, 28]. This can be associated with expression of molecular markers of apoptosis [27], but is not associated with increased labeling to detect DNA fragmentation (TUNEL labeling) as a marker of apoptosis [28].

Although some studies suggest that cytofragmentation may reflect intrinsically poor oocyte quality [29] or effects of exogenous factors such as maternal age, repeated gonadal hyperstimulation, exogenous gonadotropin dosage, and embryo culture conditions [19, 30–36], other studies indicate that the embryonic genome regulates cytofragmentation [27, 37, 38]. In humans, cytofragmentation occurs primarily from the six- to eight-cell stage onward, immediately before or at the time of genome activation [39, 40]. Likewise, cytofragmentation as early as the mid two-cell stage in mice also corresponds to the time just before the major genome activation event [27, 28]. In humans, embryo quality is determined during the zygote stage [40], and the paternal genotype can affect early embryo quality and cytofragmentation [41]. The incidence of cytofragmentation in two-cell-stage mouse embryos is influenced by the combination of maternal and paternal genotypes [27, 28]. Thus, early gene activity may affect the incidence of cytofragmentation.

To better understand how genetic factors may interact with epigenetic or cytoplasmic factors, and to what degree parental genomes may cooperatively regulate early processes such as cytofragmentation, we have undertaken studies in a murine genetic system. In this system, both maternal and paternal genotypes affect the incidence of blastomere fragmentation at the two-cell stage. In this study, we have examined the relative contributions of the maternal genome versus the ooplasm to the maternal genotype effect. We show here that the maternal pronucleus (PN) plays a predominant role in controlling this process, that this effect of the maternal PN is transcription-dependent, and that the ooplasm plays a lesser role in the overall effect of maternal genotype.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Embryo Isolation and Culture

Embryos were obtained from adult (8- to 15-wk-old) female mice superovulated by the injection of eCG (Calbiochem, San Diego, CA) and hCG (Sigma-Aldrich, St. Louis, MO) 48 h later. Females received 5 IU of each hormone. All embryos were isolated at the one-cell stage at approximately 19 h post-hCG (hphCG). Adherent cumulus cells were removed by digestion with hyaluronidase (ICN Pharmaceuticals, Costa Mesa, CA, 500 U/mg) at a final concentration of approximately 120 U/ml in M2 medium at room temperature. Embryos were cultured in CZB medium [42] as in our previous study [28]. Embryos were examined at the late one-cell stage to remove any unfertilized eggs, morphologically abnormal embryos, or embryos with any cytoplasmic fragments. This permitted an unambiguous assessment of the frequency of cytofragmentation occurring in healthy, intact embryos during development to the two-cell stage. Cytofragmentation was assessed at 48 hphCG.

Mice of the C57BL/6 genotype were obtained from Harlan Sprague-Dawley (Indianapolis, IN), and those of the C3H/HeJ genotype were from The Jackson Laboratory (Bar Harbor, ME). All studies adhered to procedures consistent with the National Research Council's Guide for the Care and Use of Laboratory Animals.

Pronuclear Transfer

Pronuclear transfers were performed as described [43, 44]. Briefly, embryos were isolated from the oviducts of successfully mated, superovulated females, and then treated with 10 µg/ml cytochalasin B (Sigma-Aldrich) and 0.4 µg/ml demecolcine (Sigma-Aldrich) at least 20 min before manipulation. Pronuclei were then exchanged using sharpened, beveled pipettes (approximately 25 µm inner diameter). Low-energy pulses were delivered to the pipette tip using a piezo pipette driver to facilitate zona penetration. Maternal pronuclei were removed and replaced with maternal pronuclei from other embryos. During maternal PN removal, the second polar body and degenerated first polar bodies were removed. After transfer of a PN-containing karyoplast to the perivitelline space, embryos were returned to culture for approximately 30 min. Electrofusion (900 V/cm, 10 µsec) was performed in fusion medium (275 mM mannitol, 0.05 mM CaCl2, 0.10 mM MgSO4, 0.3% BSA). Only constructs that fused after a single pulse were included in the analysis. After fusion, embryos were examined for the presence of any small cytoplasmic blebs, and such embryos were discarded, leaving just single cell, intact embryos for the analysis (Fig. 1). Embryos were examined again at the late one-cell stage to ensure that no fragmentation had occurred. Embryos were then cultured overnight and examined at approximately 48 hphCG for signs of cyto-fragmentation.



View larger version (117K):
[in this window]
[in a new window]
  		FIG. 1. Representative photographs of fragmented and nonfragmented embryos. A) Nonfragmented fertilized one-cell embryo. B) Nonfragmented two-cell embryo. C–E) Grades 1–3 fragmented two-cell stage embryos. F) Maternal PN transfer embryo before karyoplast fusion (note, polar body has been removed). G) Maternal PN transfer embryo after karyoplast fusion. H) Nonfragmented maternal PN transfer two-cell stage embryo. I–K) Grades 1–3 fragmented maternal PN transfer two-cell stage embryos. The mouse embryo is approximately 80 µm in diameter

Analysis of Cytofragmentation

Embryos were examined by 320x magnification phase contrast microscopy, and scored as either unfragmented, or with fragmentation graded into three categories (Fig. 1). Grade 1 fragmentation was evidenced by one or more small cytofragments smaller than the size of a polar body, and often clustered at one or both poles or in the crevice between blastomeres. Grade 2 fragmentation was evidenced by the presence of many more fragments, with total volume of fragments comprising an equivalent of less than one-half the volume of a blastomere. Grade 3 fragmentation was evidenced by larger fragments, with the total volume of fragments being approximately one-half of one blastomere or greater. The proportion of embryos falling into each category was recorded, and the significance of differences in the incidence of fragmentation between experimental groups was evaluated using a chi-square test of independence.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Maternal Genotype Effect

In previous studies, embryos from C57BL/6 females displayed a significantly greater incidence of fragmentation when sired by C3H/HeJ fathers compared with that from C57BL/6 fathers [27, 28]. This result was confirmed here (Table 1). Examples of fragmented and nonfragmented fertilized embryos are shown in Figure 1 (C–E). C3H/HeJ homozygotes previously displayed a greater incidence of cytofragmentation than C57BL/6 homozygous embryos, but the difference was not found to be statistically significant [28]. A much larger number of C3H/HeJ homozygous embryos was assayed here. The embryos were scored for fragmentation at a slightly later time during the two-cell stage (48 hphCG) than in the previous study, as a precaution to ensure that cytofragmentation had reached its fullest extent and that cellular fragments were not incorrectly attributed to transient blebs that might arise at cleavage. Also, embryo examinations were conducted at a higher magnification than in the previous study for greater accuracy in grading. With this larger sample size and the other changes in the assay, the comparison here revealed that the incidence of cytofragmentation was significantly greater among the C3H/HeJ homozygous embryos than C57BL/6 homozygotes. Thus, although this difference did not reach the level of statistical significance previously, these data indicate that indeed, embryos from C3H/HeJ females are more prone to cytofragmentation than those from C57BL/6 females. No statistically significant effect of paternal genotype was observed for fertilized embryos from C3H/HeJ females. These data, based on larger sample sizes than our previous study [28], indicate a clear effect of maternal genotype on the incidence of cytofragmentation, and further indicate that the paternal genotype effect may be manifested only where an otherwise low incidence of cytofragmentation occurs, as for example, when using fertilized C57BL/ 6 oocytes.


View this table:
[in this window]
[in a new window]
  		TABLE 1. Cytofragmentation of mouse two-cell stage embryos

The Cellular Basis for the Maternal Genotype Effect

To examine the basis for the maternal genotype effect, we employed maternal pronuclear transfer to create embryos in which the ooplasm and the maternal genome were of different origins (Fig. 1, F–H and Fig. 2). A total of 1822 nuclear transfer embryos were produced for these studies. We observed a consistent and strong effect of maternal PN strain of origin on the rate of cytofragmentation (Fig. 1, I– K and Table 2). Specifically, a C3H/HeJ maternal PN consistently produced a high rate of fragmentation and a C57BL/6 maternal PN consistently produced a lower rate of fragmentation.



View larger version (27K):
[in this window]
[in a new window]
  		FIG. 2. Schematic illustration of maternal PN transfers performed. Stippled ooplasm and black PN are C57BL/6 (denoted B), and white ooplasm and white PN are C3H/HeJ (denoted C). The combinations of ooplasm, maternal PN, and paternal PN produced are shown below the embryos, and are those used in Table 2


View this table:
[in this window]
[in a new window]
  		TABLE 2. Fragmentation of mouse two-cell stage embryos produced by maternal pronuclear transfer

The maternal PN studies accomplish the equivalent of nearly total ooplasm exchange, as the maternal PN is separated from its ooplasm during the transfer and introduced into a new ooplasm. Thus, the data in Table 2 also permit the effects of ooplasm to be evaluated. There was no significant difference between constructs made with C57BL/6 and C3H/HeJ recipient ooplasm, even at the level of severity of cytofragmentation. In particular, for constructs of equal resulting genotype, there was no difference in cyto-fragmentation attributable to the ooplasm alone (e.g., compare BCB with CCB constructs, and compare CCC with BCC constructs). A C57BL/6 maternal PN was even able to confer a lower rate of fragmentation on constructs prepared with C3H/HeJ ooplasm (compare CCC with CBC, and CCB with CBB). The absence of any significant effect of recipient ooplasm also excludes the possibility that the small amount of ooplasm transferred with the maternal PN has any discernible effect. These data indicate that the maternal PN is primarily responsible for the maternal genotype effect.

The paternal genotype effect was not evident in these maternal PN transfer studies, even for constructs prepared with C57BL/6 oocytes (i.e., compare BBB and BBC). There was a tendency to observe lower rates of fragmentation when the paternal genotype and the ooplasm genotype were the same, but this difference was not statistically significant in any combination. As stated above, the paternal genotype effect may be most apparent on a background of low overall incidence of cytofragmentation. The overall incidence of fragmentation in maternal PN transfer embryos was increased compared with that of unmanipulated embryos (e.g., 6.91% versus 3.45% for C57BL/6 homozygous constructs and embryos, respectively; Tables 1 and 2). This increased incidence of fragmentation in maternal PN transfer embryos may have obscured a possible effect of the paternal genotype (note: all data in Table 2 are from maternal PN transfer embryos and can be compared). These data thus indicate that, while a paternal genotype effect exists (Table 1), this effect can be obscured by procedures such as pronuclear transfer.

Effect of {alpha}-Amanitin on Fragmentation

The effect of the maternal PN on fragmentation indicated that early gene expression from the maternal PN could be required to suppress fragmentation. To test this possibility, we treated an additional 624 maternal pronuclear constructs with {alpha}-amanitin to inhibit transcription from 26 hphCG injection onward (Table 2, annotated with b). Because the paternal PN did not alter the outcome for maternal pronuclear transfer embryos, and because C57BL/6 males mated efficiently, C57BL/6 sires were employed for these studies. Treatment of constructs prepared with C57BL/6 oocytes yielded levels of fragmentation intermediate between those observed for untreated BCB and BBB constructs. A significant effect was also observed for {alpha}-amanitin treatment of CBB embryos (P < 0.05), which displayed a significantly increased rate of cytofragmentation, indicating that transcription was required for the C57BL/6 maternal PN to suppress fragmentation in a C3H/HeJ ooplasm.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The results presented here establish a role for zygotic gene function in controlling early embryo phenotype. Our data reveal a strong effect of maternal genotype on the incidence of cytofragmentation, with a paternal genotype effect also evident with some genetic combinations. The genotype of the maternal PN provides the principal component of the maternal genotype effect, with the ooplasm playing a lesser role. This maternal pronuclear effect is sensitive to {alpha}-amanitin treatment, indicating a role for early gene transcription.

The data exclude a predominant role for the ooplasm in controlling cytofragmentation. If, for example, C57BL/6 ooplasm were to inhibit cytofragmentation, then it would not be expected that the presence of the C3H/HeJ maternal PN would increase cytofragmentation when transferred to a C57BL/6 ooplasm. Conversely, if C3H/HeJ ooplasm were to promote cytofragmentation, then a C57BL/6 maternal PN would not be expected to overcome the effects of the C3H/HeJ recipient ooplasm. The reciprocal independence of cytofragmentation on ooplasm excludes the possibility of a nonspecific effect of culture medium, as effects of culture medium would most likely be exerted via the ooplasm to affect cytofragmentation at this early stage. Because ooplasm of either type could display either high or low fragmentation, depending on the maternal PN present, such a culture effect does not appear evident. Thus, when the results of all combinations shown in Table 2 are considered together with the {alpha}-amanitin effect, it is clear that the maternal PN, not the ooplasm or other extranuclear oocyte components, plays the predominant role in controlling the incidence of cytofragmentation.

Although the maternal PN exerts the predominant role in controlling cytofragmentation, a lesser effect of the ooplasm likely exists. One indication of this is the intermediate level of fragmentation observed following {alpha}-amanitin treatment of maternal PN transfer constructs made with C57BL/6 oocytes. If a C57BL/6 maternal PN expresses a gene or genes required to suppress cytofragmentation, then the effect of {alpha}-amanitin treatment should be similar between constructs prepared with C3H/HeJ and C57BL/6 ooplasm (i.e., {alpha}-amanitin treatment should increase fragmentation in BBB construct to the highest level). Although {alpha}-amanitin significantly reduced the ability of C57BL/6 maternal PN to suppress cytofragmentation in C3H/HeJ ooplasm and led to a high level of cytofragmentation, the same treatment led only to an intermediate level of cyto-fragmentation in constructs prepared with C57BL/6 ooplasm. Thus, the requirement for suppression of cytofragmentation may vary with ooplasm strain of origin, with the C57BL/6 ooplasm being endowed with an increased supply of anticytofragmentation gene products relative to C3H/HeJ ooplasm. The expression of anticytofragmentation gene products from the C57BL/6 maternal PN after fertilization may augment this maternal (ooplasmic) supply produced from the C57BL/6 maternal genome during oogenesis. If such an ooplasmic endowment exists, then the high level of cytofragmentation observed in untreated BCB constructs could reflect a combination of lack of expression of anticytofragmentation genes and overexpression of cytofragmentation-promoting genes from the C3H/HeJ maternal PN. The intermediate level of cytofragmentation observed in {alpha}-amanitin-treated BCB constructs would thus be expected to render equivalent levels of cytofragmentation in {alpha}-amanitin-treated BCB and BBB constructs, which indeed was observed. Thus, the greater predisposition of C3H/HeJ homozygotes compared with C57BL/6 homozygotes to display cytofragmentation (Table 1) likely reflects the combined effects of ooplasm and maternal PN.

To our knowledge, the effect of the maternal PN on cytofragmentation is the earliest documented effect of the embryonic genome on phenotype during development, and the first apparent effect of the gene transcription that occurs before the major genome activation event. Although several previous studies have revealed very early gene transcription activity (reviewed in [5]), none have associated this activity with an effect on immediate embryo phenotype.

Although it has been appreciated for some time that embryonic gene transcription occurs during the one-cell stage in several different mammalian species [5], the function of this early transcriptional activity has not been elucidated. Our data indicate that one function of early zygotic gene transcription may be to suppress the pathway leading to cytofragmentation and cell death, and thus maintain blastomere integrity and promote embryo survival. Consistent with this, {alpha}-amanitin treatment of maternal pronuclear transfer embryos modulated the effect of the maternal PN on the incidence of cytofragmentation, as is seen particularly for the CBB constructs. Thus, transcription appears to play a significant role in this early effect of the maternal PN. Also consistent with such an early role for gene transcription, homozygosity for a null mutation in the gene encoding the mouse regulator of G protein signaling (RGS14), which is transcribed in the one-cell embryo, leads to fragmentation at the two-cell stage, a phenotype related to cytokinesis (L.M. McCaffrey, D. Siderovski, and S. D'Souza, University of Western Ontario, personal communication). These observations for RGS14 also support an early role for early embryonic gene transcription in early processes related to cytofragmentation.

While the paternal PN exerts an effect in fertilized embryos obtained from C57BL/6 mothers, the paternal PN does not exert a strong effect in the context of maternal PN transfer. That paternal PN thus behaved differently from maternal PN of the same strain indicates a functional difference between the maternal and paternal genomes. This difference could be imposed on the two genomes either during gametogenesis (i.e., genomic imprinting) or after fertilization [45–55]. In either case, this difference between maternal and paternal pronuclear function likely contributes to a need for cooperative interactions between the two genomes during early development. A requirement for correct interactions between complementary, differentially imprinted parental genomes during the first one to two cell cycles could serve as an early selection mechanism to promote survival of high-quality embryos [27]. Genetic diversity may lead to some maternal-paternal genotype combinations that are less compatible than others, a situation that could contribute to speciation during evolution. Inheritance of a wild-type allele of RGS14 from either parent prevents cytofragmentation in heterozygous RGS14 mutant embryos, indicating a lack of imprinting for this gene. Thus, genes other than RGS14 are likely expressed to account for the specific effect of the maternal PN. Cytofragmentation is thus likely to be a consequence of disruption in more than one pathway or early process in the early embryo. Further studies directed toward identifying the relevant genes controlling cytofragmentation will be invaluable, both for understanding the mechanism of cytofragmentation and for understanding the basis for the genetic and epigenetic effects seen here.

The finding that the maternal genome can exert a predominant effect on the incidence of cytofragmentation, independently of ooplasm origin, may be relevant to the clinical evaluation of human oocyte and embryo quality. Blastomere fragmentation is widely attributed to "oocyte quality." Novel approaches for improving oocyte quality include germinal vesicle transfer and ooplasm transfer [56, 57]. Such approaches are founded on the assumption that it is the ooplasm specifically that is responsible for compromised fertility. The results presented here indicate, however, that cytoplasmic factors, including mitochondrial properties, need not always be the only cause of poor embryo quality. Rather, genetic or developmental variation in the programming of the oocyte genome for early functions can also lead to defects such as cytofragmentation. In such cases, ooplasm manipulation procedures could be of limited value in overcoming compromised fertility. Additionally, recent studies of the human have indicated important roles for paternally derived factors in fertility [41, 58]. Further elucidation of the nature of these early genome functions and their consequences should thus be of value to both basic and clinical reproductive biology.


   ACKNOWLEDGMENTS
 
We thank Luke Martin McCaffrey, David Siderovski, and S.J. Tony D'Souza for sharing their unpublished data on RGS14 with us. We also thank Lisa Latham for comments on the manuscript.


   FOOTNOTES
 
1 Supported by grant HD 41440 from the National Institute of Child Health and Human Development. Back

2 Correspondence: Keith Latham, The Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, 3307 N. Broad Street, Philadelphia, PA 19140. FAX: 215 707 1454; klatham{at}temple.edu Back

3 Current address: Advanced Cell Technology, One Innovation Drive, Biotech Three, Worcester, MA 01605 Back

Received: 22 August 2004.

First decision: 17 September 2004.

Accepted: 29 October 2004.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Hill DP, Shakes DC, Ward S, Strome S, Sperm-supplied product essential for initiation of normal embryogenesis in Caenorhabditis elegans is encoded by the paternal-effect embryonic-lethal gene, spe-11. Dev Biol 1989 136:154-166[CrossRef][Medline]
  2. Browning H, Strome S, A sperm-supplied factor required for embryogenesis in C. elegans. Development 1996 122:391-404[Abstract]
  3. Fitch KR, Yasuda GK, Owens KN, Wakimoto BT, Paternal effects in Drosophila: implications for mechanisms of early development. Dev Biol 1998 38:1-34
  4. Latham KE, Mechanisms and control of embryonic genome activation in mammalian embryos. Int Rev Cytol 1999 193:71-124[Medline]
  5. Latham KE, Schultz RM, Embryonic genome activation. Frontiers in bioscience: molecular and biochemical control of mammalian preimplantation. Development 2001 6:D748-D759
  6. Henery CC, Miranda M, Wiekowski M, Wilmut I, DePamphilis ML, Repression of gene expression at the beginning of mouse development. Dev Biol 1995 169:448-460[CrossRef][Medline]
  7. Aoki F, Worrad DM, Schultz RM, Regulation of transcriptional activity during the first and second cell cycles in the preimplantation mouse embryo. Dev Biol 1997 181:296-307[CrossRef][Medline]
  8. Bomar J, Moreira P, Balise JJ, Collas P, Differential regulation of maternal and paternal chromosome condensation in mitotic zygotes. J Cell Sci 2002 115:2931-2940[Abstract/Free Full Text]
  9. Cowell IG, Aucott R, Mahadevaiah SK, Burgoyne PS, Huskisson N, Bongiorni S, Prantera G, Fanti L, Pimpinelli S, Wu R, Gilbert DM, Shi W, Fundele R, Morrison H, Jeppesen P, Singh PB, Heterochromatin, HP1 and methylation at lysine 9 of histone H3 in animals. Chromosoma 2002 111:22-36[CrossRef][Medline]
  10. Santos F, Hendrich B, Reik W, Dean W, Dynamic reprogramming of DNA methylation in the early mouse embryo. Dev Biol 2002 241:172-182[CrossRef][Medline]
  11. Jurisicova A, Varmuza S, Casper RF, Involvement of programmed cell death in preimplantation embryo demise. Hum Reprod Update 1995 1:558-566[Abstract/Free Full Text]
  12. Antczak M, Van Blerkom J, Temporal and spatial aspects of fragmentation in early human embryos: possible effects on developmental competence and association with the differential elimination of regulatory proteins from polarized domains. Hum Reprod 1999 14:429-447[Abstract/Free Full Text]
  13. Giorgetto C, Terrou P, Auquier P, Hans E, Spach JL, Salzmann J, Roulier R, Embryo score to predict implantation after in-vitro fertilization: based on 957 single embryo transfers. Hum Reprod 1995 10:2427-2431[Abstract/Free Full Text]
  14. Ebner T, Yaman C, Moser M, Sommergruber M, Polz W, Tews G, Embryo fragmentation in vitro and its impact on treatment and pregnancy outcome. Fertil Steril 2001 76:281-285[CrossRef][Medline]
  15. Hoover L, Baker A, Check J, Lurie D, O'Shaughnessy A, Evaluation of a new embryo-grading system to predict pregnancy rates following in vitro fertilization. Gynecol Obstet Invest 1995 40:151-157[Medline]
  16. Van Blerkom J, Davis P, Alexander S, A microscopic and biochemical study of fragmentation phenotypes in stage-appropriate human embryos. Hum Reprod 2001 16:719-729[Abstract/Free Full Text]
  17. Alikani M, Cohen J, Tomkin G, Garrisi GJ, Mack C, Scott RT, Human embryo fragmentation in vitro and its implications for pregnancy and implantation. Fertil Steril 1999 71:836-842[CrossRef][Medline]
  18. Lee TH, Wu MY, Chen MJ, Chao KH, Ho HN, Yang YS, Nitric oxide is associated with poor embryo quality and pregnancy outcome in in vitro fertilization cycles. Fertil Steril 2004 82:126-131[CrossRef][Medline]
  19. Cooke S, Quinn P, Kime L, Ayres C, Tyler JP, Driscoll GL, Improvement in early human embryo development using new formulation sequential stage-specific culture media. Fertil Steril 2002 78:1254-1260[CrossRef][Medline]
  20. Jurisicova A, Antenos M, Varmuza S, Tilly JL, Casper RF, Expression of apoptosis-related genes during human preimplantation embryo development: potential roles for the Harakiri gene product and Caspase-3 in blastomere fragmentation. Mol Hum Reprod 2003 9:133-134[Abstract/Free Full Text]
  21. Brison D, Schultz RM, Apoptosis during mouse blastocyst formation: evidence for a role for survival factors including transforming growth factor. Biol Reprod 1997 56:1088-1096[Abstract]
  22. Brison DR, Schultz RM, Increased incidence of apoptosis in transforming growth factor alpha-deficient mouse blastocysts. Biol Reprod 1998 59:136-144[Abstract/Free Full Text]
  23. Brewster JL, Martin SL, Toms J, Goss D, Wang K, Zachrone K, Davis A, Carlson G, Hood L, Coffin JD, Deletion of Dad1 in mice induces an apoptosis-associated embryonic death. Genesis 2000 26:271-278[CrossRef][Medline]
  24. Liu L, Keefe DL, Cytoplasm mediates both development and oxidation-induced apoptotic cell death in mouse zygotes. Biol Reprod 2000 62:1828-1834[Abstract/Free Full Text]
  25. Liu L, Trimarchi JR, Keefe DL, Involvement of mitochondria in oxidative stress-induced cell death in mouse zygotes. Biol Reprod 2000 62:1745-1753[Abstract/Free Full Text]
  26. Moley KH, Diabetes and preimplantation events of embryogenesis. Semin Reprod Endocrinol 1999 17:137-151[Medline]
  27. Jurisicova A, Latham KE, Casper RF, Varmuza SL, Expression and regulation of genes associated with cell death during murine preimplantation embryo development. Mol Reprod Dev 1998 51:243-253[CrossRef][Medline]
  28. Hawes SM, Chung YG, Latham KE, Genetic and epigenetic factors affecting blastomere fragmentation in preimplantation stage mouse embryos. Biol Reprod 2001 65:1050-1056[Abstract/Free Full Text]
  29. Salumets A, Suikkari AM, Mols T, Soderstrom-Anttila V, Tuuri T, Influence of oocytes and spermatozoa on early embryonic development. Fertil Steril 2002 78:1082-1087[CrossRef][Medline]
  30. Sato F, Marrs RP, The effect of pregnant mare serum gonadotropin on mouse embryos fertilized in vivo or in vitro. J In Vitro Fertil Embryo Transf 1986 3:353-357[CrossRef][Medline]
  31. Tarin JJ, Perez-Albala S, Cano A, Cellular and morphological traits of oocytes retrieved from aging mice after exogenous ovarian stimulation. Biol Reprod 2001 65:141-150[Abstract/Free Full Text]
  32. Van Blerkom J, Davis P, Differential effects of repeated ovarian stimulation on cytoplasmic and spindle organization in metaphase II mouse oocytes matured in vivo and in vitro. Hum Reprod 2001 16:757-764[Abstract/Free Full Text]
  33. Ziebe S, Loft A, Petersen JH, Andersen AG, Lindenberg S, Petersen K, Andersen AN, Embryo quality and developmental potential is compromised by age. Acta Obstet Gynecol Scand 2001 80:169-174[CrossRef][Medline]
  34. Spanos S, Becker DL, Winston RM, Hardy K, Anti-apoptotic action of insulin-like growth factor-I during human preimplantation embryo development. Biol Reprod 2000 63:1413-1420[Abstract/Free Full Text]
  35. Bedaiwy MA, Falcone T, Mohamed MS, Aleem AA, Sharma RK, Worley SE, Thornton J, Agarwal A, Differential growth of human embryos in vitro: role of reactive oxygen species. Fertil Steril 2004 82:593-600[CrossRef][Medline]
  36. Makarevich AV, Markkula M, Apoptosis and cell proliferation potential of bovine embryos stimulated with insulin-like growth factor I during in vitro maturation and culture. Biol Reprod 2002 66:386-392[Abstract/Free Full Text]
  37. Kaito C, Kai M, Higo T, Takayama E, Fukamachi H, Sekimizu K, Shiokawa K, Activation of the maternally preset program of apoptosis by microinjection of 5-aza-2'-deoxycytidine and 5-methyl-2'-deoxycytidine-5'-triphosphate in Xenopus laevis embryos. Dev Growth Differ 2001 43:383-390[CrossRef][Medline]
  38. Liu L, Trimarchi JR, Keefe DL, Haploidy but not parthenogenetic activation leads to increased incidence of apoptosis in mouse embryos. Biol Reprod 2002 66:204-210[Abstract/Free Full Text]
  39. Hardy K, Apoptosis in the human embryo. Rev Reprod 1999 4:125-134[Abstract]
  40. Hardy K, Spanos S, Becker D, Iannelli P, Winston RM, Stark J, From cell death to embryo arrest: mathematical models of human preimplantation embryo development. Proc Natl Acad Sci U S A 2001 98:1655-1660[Abstract/Free Full Text]
  41. Tesarik J, Mendoza C, Greco E, Paternal effects acting during the first cell cycle of human preimplantation development after ICSI. Hum Reprod 2002 17:184-189[Abstract/Free Full Text]
  42. Chatot CL, Ziomek CA, Bavister BD, Lewis JL, Torres I, An improved culture medium supports development of random-bred 1-cell mouse embryos in vitro. J Reprod Fertil 1989 86:679-688[Abstract]
  43. Latham KE, Solter D, Transplantation of nuclei to oocytes and embryos. Methods Enzymol 1993 225:719-732[Medline]
  44. Latham KE, Westhusin M, Nuclear transplantation and cloning in mammals. In: Tuan RS, Lo CW (eds.), Methods in Molecular Biology, vol. 136, Developmental Biology Protocols, vol. II. Totowa, New Jersey: Humana Press; 1999:405–425
  45. Surani MA, Kothary R, Allen ND, Singh PB, Fundele R, Ferguson-Smith AC, Barton SC, Genome imprinting and development in the mouse. Dev Suppl 1990;89–98
  46. Latham KE, Solter D, Effect of egg composition on the developmental capacity of androgenetic mouse embryos. Development 1991 113:561-568[Abstract]
  47. Latham KE, Strain-specific differences in mouse oocytes and their contributions to epigenetic inheritance. Development 1994 120:3419-3426[Abstract]
  48. Latham KE, Sapienza C, Localization of genes encoding egg modifiers of paternal genome function to mouse chromosomes one and two. Development 1998 125:929-935[Abstract]
  49. Adenot PG, Mercier Y, Renard JP, Thompson EM, Differential acetylation of paternal and maternal chromatin precedes DNA replication and differential transcriptional activity in pronuclei of 1-cell mouse embryos. Development 1997 124:4615-4625[Abstract]
  50. Haines TR, Rodenhiser DI, Ainsworth PJ, Allele-specific non-CpG methylation of the Nf1 gene during early mouse development. Dev Biol 2001 240:585-598[CrossRef][Medline]
  51. Howell CY, Steptoe AL, Miller MW, Chaillet JR, cis-Acting signal for inheritance of imprinted DNA methylation patterns in the preimplantation mouse embryo. Mol Cell Biol 1998 18:4149-4156[Abstract/Free Full Text]
  52. Latham KE, Epigenetic modification and imprinting of the mammalian genome during development. Curr Top Dev Biol 1999 43:1-49[Medline]
  53. Reik W, Römer I, Barton SC, Surani MA, Howlett SK, Klose J, Adult phenotype in the mouse can be affected by epigenetic events in the early embryo. Development 1993 119:933-942[Abstract]
  54. Roemer I, Reik W, Dean W, Kloase J, Epigenetic inheritance in the mouse. Curr Biol 1997 7:277-280[CrossRef][Medline]
  55. Pickard B, Dean W, Engemann S, Bergmann K, Fuermann M, Jung M, Reis A, Allen N, Reik W, Walter J, Epigenetic targeting in the mouse zygote marks DNA for later methylation: a mechanism for maternal effects in development. Mech Dev 2001 103:35-34[CrossRef][Medline]
  56. Cohen J, Scott R, Schimmel T, Levron J, Willadsen S, Birth of an infant after transfer of anucleate donor oocyte cytoplasm into recipient eggs. Lancet 1997 350:186-187[CrossRef][Medline]
  57. Zhang J, Wang CW, Krey L, Liu H, Meng L, Blaszczyk A, Adler A, Grifo J, In vitro maturation of human preovulatory oocytes reconstructed by germinal vesicle transfer. Fertil Steril 1999 71:726-731[CrossRef][Medline]
  58. Check JH, Cochrane H, Yuan W, Wilson C, Evidence using a shared oocyte pool that the sperm rather than the oocyte in some cases may be responsible for the production of embryos with a high percentage of fragmented blastomeres—case report. Clin Exp Obstet Gynecol 2004 31:139-140[Medline]



This article has been cited by other articles:


Home page
 Biol. Reprod.Home page
Z. Han, N. R. Mtango, B. G. Patel, C. Sapienza, and K. E. Latham
Hybrid Vigor and Transgenerational Epigenetic Effects on Early Mouse Embryo Phenotype
Biol Reprod, October 1, 2008; 79(4): 638 - 648.
[Abstract] [Full Text] [PDF]

Home page
 DevelopmentHome page
L.-B. Wan, H. Pan, S. Hannenhalli, Y. Cheng, J. Ma, A. Fedoriw, V. Lobanenkov, K. E. Latham, R. M. Schultz, and M. S. Bartolomei
Maternal depletion of CTCF reveals multiple functions during oocyte and preimplantation embryo development
Development, August 15, 2008; 135(16): 2729 - 2738.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
72/3/612    most recent
biolreprod.104.035444v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.
Agricola
Right arrow Articles by Han, Z.
Right arrow Articles by Latham, K. E.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS