Shiokawa K , Aso M , Kondo T , Uchiyama H , Kuroyanagi S , Takai J , Takahashi S , Kajitani M , Kaito C , Sekimizu K , Takayama E , Igarashi K , Hara H .

	Figure 1. Induction of apoptosis by injection of Xenopus SAMDC mRNA. (A) A control embryo injected with distilled water. (B) A fertilized egg injected with Xenopus SAMDC mRNA (100 pg), and cultured in a slightly hypertonic 1 X Steinberg’s solution in order to protect dissociated cells from osmotic shock. White cells are dissociated cells. These cells appear in the region where mRNA was injected. Embryos were filmed at early gastrula stage. From Takayama et al. (2004).
	Figure 2. Apoptosis induced in a half portion of an embryo. Only one blastomere of a 2-celled embryo was injected with a mixture of SAMDC mRNA (1 ng/egg) and GFP mRNA (100 pg/egg), and embryos were filmed at early blastula (A, B) and early gastrula (C, D) stage using the visible light (A, C) and UV light (B, D). In B, cells expressing GFP, hence containing SAMDC mRNA, cleaved normally, but after MBT one half portion of the embryo which expressed GFP (D) underwent cell dissociation (C). (Kuroyanagi S, Shiokawa K, unpublished).
	Figure 3. Cell dissociation induced by microinjection of 5-aza-2′-deoxycytidine (4 pmole/egg). Embryos were cultured in 1 X Steinberg’s solution and filmed at late blastula stage. From Kaito et al. (2001).
	Figure 4. Apoptosis-like reaction in colchicine-treated Xenopus embryos. Xenopus fertilized eggs were cultured in 1 X Steinberg’s solution containing 1 mM colchicine. Embryos were filmed at early blastula stage. (Suwa M, Shiokawa K, unpublished).
	Figure 5. Rescue of SAMDC mRNA-injected Xenopus embryos by Bcl-2. When Xenopus fertilized eggs were injected with SAMDC mRNA (1 ng/egg) alone, embryos were dissociated shortly after MBT (A), and remained dissociated in 1 X Steinberg’s solution (B) even after 12 hrs (at which time control embryos reached stage 22 tailbud embryos). When fertilized eggs were co-injected with SAMDC mRNA (1 ng/egg) and Bcl-2 mRNA (2 ng/egg), cell dissociation did not take place at late blastula stage (C), and embryos developed to the tailbud stage (stage 22) (D). The extent of the rescue by Bcl-2 from SAMDC-induced apoptosis varied depending on the dosage-combination of SAMDC and Bcl-2 mRNAs (E). From Kai et al. (2000).
	Figure 6. Northern blot analysis of caspase mRNAs in Xenopus embryos. Fertilized eggs were injected with either SAMDC mRNA (100 pg/egg) or distilled water, and RNAs were isolated from embryos, and subjected to northern blot analysis. From Takayama et al. (2004).
	Figure 7. Northern blot and RT-PCR analyses for caspase-8 and -9 mRNAs in p53 mRNA- or SAMDC mRNA-injected embryos. Fertilized eggs were injected (+) or not (−) injected with p53 or SAMDC mRNA (1 ng each/embryo), and cultured in 1 X Steinberg’s solution. RNAs were isolated from embryos at stage 6.5 (late cleavage stage) or stage 8.5 (midblastula stage). Upper white panels: RNAs separated on a 1% agarose gel containing formaldehyde were transferred to a nylon membrane, and hybridized with 32P-labelled specific probes for Xenopus caspase-8 and 9. Middle black panel: 28S and 18S rRNAs stained with ethidium bromide on 1% agarose gel. This profile is before blotting. Lower black panels: RNAs were subjected to RT-PCR. The signal obtained for caspase-8 and caspase-9 mRNA was 396 bp and 539bp, respectively. Caspase-8 mRNA expression was induced only in SAMDC mRNA-injected cleavage stage and midblastula stage embryos, whereas caspase-9 mRNA occurred as a maternally-provided RNA. From Shiokawa et al. (2005).
	Figure 8. A model which shows sequence of events in activation of caspase system in SAMDC mRNA-overexpressed and p53 mRNA-overexpressed embryos, with special reference to the recruitment of mRNAs.
	Figure 9. GFP-tracing of SAMDC mRNA-injected cells at the tadpole stage. Embryos were injected with processing-defective (A) or wild-type (B) SAMDC mRNA together with GFP mRNA into one animal side blastomere at the 8-cell stage, and GFP luminescence was examined at the tadpole stage (32 hrs post-fertilization). Note that the embryo in B is shorter in body length than that in A due to apoptotic loss of a certain amount of cell mass at MBT within the blastocel. Both embryos were too large to be taken in a photograph, so embryos were taken in two photographs and tadpoles were constructed by combining the two photographs together. The bar is 5 mm. From Kai et al. (2003).
	Figure 10. Effects on development of SAMDC mRNA injection into an animal side blastomere of either future dorsal or ventral side of the 16-cell stage embryo. Embryos were injected with SAMDC mRNA (130 pg) into one animal side blastomere of either future dorsal (B) or ventral (C) side at 16-cell stage as schematically shown in the diagram in the left, and cultured until the tailbud stage. (A) A control uninjected embryo. In B, the cement gland is missing (arrowheads), and furthermore, head part is absent (acephaly) (lower arrowhead). In C, posterior and ventral structures such as trunk and tail are poorly developed (arrowheads), or tail is curved upwards (lower arrowhead). From Kai et al. (2003).
	Figure 11. A model which shows how early development proceeds. This model suggests possible occurrence of apoptotic check point which functions as a surveillance or “fail-safe” mechanism in Xenopus early embryonic development. Fertilized eggs cleave rapidly until the early blastula stage. At MBT, the “first developmental checkpoint” comes when G1 phase first appears. We assume that this check mechanism determines cell-autonomously if the cell continues or stops development to be eliminated by execution of the maternally-inherited program of apoptosis. However, even when apoptosis was executed, embryos follow two different courses. If the number of apoptotic cells is large, the whole embryo stops development and dies. However, if the number of apoptotic cells is small, they are confined within the blastocoel and the embryo itself continues on development. Cells to be eliminated are segregated into the blastocoel. If such cells came out to the perivitteline space, the whole embryo will be dissolved due to osmotic shock (eggs are laid in the water), and the maternally-inherited program of apoptosis will not serve as a fail-safe mechanism.
	Figure 12. Three characteristic profiles of RNA synthetic patterns as studied by gel electrophoresis of radioactively-labeled RNA at each stage. Dotted, shaded and black areas are for the product of RNA polymerase II, III, and I, respectively, which are heterogeneous mRNA-like RNA, tRNA, and rRNA, respectively. Distance of migration and amount of radioactivity are in arbitrary units. From Shiokawa et al. (1941).

Anderson, Ionizing radiation induces apoptosis and elevates cyclin A1-Cdk2 activity before but not after the midblastula transition in Xenopus. 1997, Pubmed, Xenbase

Anderson, Ionizing radiation induces apoptosis and elevates cyclin A1-Cdk2 activity before but not after the midblastula transition in Xenopus. 1997, Pubmed , Xenbase
Andéol, Early transcription in different animal species: implication for transition from maternal to zygotic control in development. 1994, Pubmed
BROWN, RNA SYNTHESIS DURING THE DEVELOPMENT OF XENOPUS LAEVIS, THE SOUTH AFRICAN CLAWED TOAD. 1964, Pubmed , Xenbase
Brown, Synthesis and accumulation of DNA-like RNA during embryogenesis of Xenopus laevis. 1966, Pubmed , Xenbase
Busby, Spacer sequences regulate transcription of ribosomal gene plasmids injected into Xenopus embryos. 1983, Pubmed , Xenbase
Carter, Loss of XChk1 function triggers apoptosis after the midblastula transition in Xenopus laevis embryos. 2003, Pubmed , Xenbase
Carter, Cyclin A1/Cdk2 is sufficient but not required for the induction of apoptosis in early Xenopus laevis embryos. 2006, Pubmed , Xenbase
Chapman, Mechanism of Brefeldin A-Induced Growth Inhibition and Cell Death in Human Prostatic Carcinoma Cells. 1999, Pubmed
Cruz-Reyes, Cloning, characterization and expression of two Xenopus bcl-2-like cell-survival genes. 1995, Pubmed , Xenbase
DETTLAFF, CELL DIVISIONS, DURATION OF INTERKINETIC STATES AND DIFFERENTIATION IN EARLY STAGES OF EMBRYONIC DEVELOPMENT. 1964, Pubmed
Davis, Sequestered end products and enzyme regulation: the case of ornithine decarboxylase. 1992, Pubmed
Earnshaw, Analysis of the distribution of the INCENPs throughout mitosis reveals the existence of a pathway of structural changes in the chromosomes during metaphase and early events in cleavage furrow formation. 1991, Pubmed
Etkin, Transformed Xenopus embryos as a transient expression system to analyze gene expression at the midblastula transition. 1985, Pubmed , Xenbase
Finkielstein, A role for G1/S cyclin-dependent protein kinases in the apoptotic response to ionizing radiation. 2002, Pubmed , Xenbase
Friedlander, Expression of a dominant negative mutant of interleukin-1 beta converting enzyme in transgenic mice prevents neuronal cell death induced by trophic factor withdrawal and ischemic brain injury. 1997, Pubmed
GUIRARD, EFFECT OF POLYAMINE STRUCTURE ON GROWTH STIMULATION AND SPERMINE AND SPERMIDINE CONTENT OF LACTIC ACID BACTERIA. 1964, Pubmed
GURDON, CYTOPLASMIC REGULATION OF RNA SYNTHESIS AND NUCLEOLUS FORMATION IN DEVELOPING EMBRYOS OF XENOPUS LAEVIS. 1965, Pubmed , Xenbase
Gurdon, A community effect in animal development. , Pubmed , Xenbase
Heasman, Patterning the early Xenopus embryo. 2006, Pubmed , Xenbase
Heby, Molecular genetics of polyamine synthesis in eukaryotic cells. 1990, Pubmed
Hensey, A developmental timer that regulates apoptosis at the onset of gastrulation. 1997, Pubmed , Xenbase
Hensey, Programmed cell death during Xenopus development: a spatio-temporal analysis. 1998, Pubmed , Xenbase
Hoever, Overexpression of wild-type p53 interferes with normal development in Xenopus laevis embryos. 1994, Pubmed , Xenbase
Holliday, Gene silencing in mammalian cells by uptake of 5-methyl deoxycytidine-5'-triphosphate. 1991, Pubmed
Ikegami, Developmental activation of the capability to undergo checkpoint-induced apoptosis in the early zebrafish embryo. 1999, Pubmed , Xenbase
Johnston, The roles of Bcl-xL in modulating apoptosis during development of Xenopus laevis. 2005, Pubmed , Xenbase
Jones, Altering gene expression with 5-azacytidine. 1985, Pubmed
Kai, Overexpression of S-adenosylmethionine decarboxylase (SAMDC) activates the maternal program of apoptosis shortly after MBT in Xenopus embryos. 2000, Pubmed , Xenbase
Kai, Overexpression of S-adenosylmethionine decarboxylase (SAMDC) in Xenopus embryos activates maternal program of apoptosis as a "fail-safe" mechanism of early embryogenesis. 2003, Pubmed , Xenbase
Kaito, 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. 2001, Pubmed , Xenbase
Kane, The zebrafish midblastula transition. 1993, Pubmed
Kluck, The release of cytochrome c from mitochondria: a primary site for Bcl-2 regulation of apoptosis. 1997, Pubmed , Xenbase
Kondo, Activin receptor mRNA is expressed early in Xenopus embryogenesis and the level of the expression affects the body axis formation. 1991, Pubmed , Xenbase
Li, Cytochrome c and dATP-dependent formation of Apaf-1/caspase-9 complex initiates an apoptotic protease cascade. 1997, Pubmed
Minoura, Stimulation of circus movement by activin, bFGF and TGF-beta 2 in isolated animal cap cells of Xenopus laevis. 1995, Pubmed , Xenbase
Misumi, Novel blockade by brefeldin A of intracellular transport of secretory proteins in cultured rat hepatocytes. 1986, Pubmed
Momand, The mdm-2 oncogene product forms a complex with the p53 protein and inhibits p53-mediated transactivation. 1992, Pubmed
Moody, Fates of the blastomeres of the 16-cell stage Xenopus embryo. 1987, Pubmed , Xenbase
Nagel, Guidance of mesoderm cell migration in the Xenopus gastrula requires PDGF signaling. 2004, Pubmed , Xenbase
Nakajima, Structure, expression, and function of the Xenopus laevis caspase family. 2000, Pubmed , Xenbase
Nakakura, Synthesis of heterogeneous mRNA-like RNA and low-molecular-weight RNA before the midblastula transition in embryos of Xenopus laevis. 1987, Pubmed , Xenbase
Newmeyer, Cell-free apoptosis in Xenopus egg extracts: inhibition by Bcl-2 and requirement for an organelle fraction enriched in mitochondria. 1994, Pubmed , Xenbase
Newport, A major developmental transition in early Xenopus embryos: I. characterization and timing of cellular changes at the midblastula stage. 1982, Pubmed , Xenbase
Ninomiya, Antero-posterior tissue polarity links mesoderm convergent extension to axial patterning. 2004, Pubmed , Xenbase
Nishikawa, Cell death in the anuran tadpole tail: thyroid hormone induces keratinization and tail-specific growth inhibition of epidermal cells. 1989, Pubmed , Xenbase
Pegg, Recent advances in the biochemistry of polyamines in eukaryotes. 1986, Pubmed
Richter, A developmentally regulated, nervous system-specific gene in Xenopus encodes a putative RNA-binding protein. 1990, Pubmed , Xenbase
Richter, The mechanism for increased protein synthesis during Xenopus oocyte maturation. 1982, Pubmed , Xenbase
SHIOKAWA, DEMONSTRATION OF "POLYPHOSPHATE" AND ITS POSSIBLE ROLE IN RNA SYNTHESIS DURING EARLY DEVELOPMENT OF RANA JAPONICA EMBRYOS. 1965, Pubmed
Salvesen, Caspases: intracellular signaling by proteolysis. 1997, Pubmed
Shi, Thyroid Hormone Receptors: Mechanisms of Transcriptional Regulation and Roles during Frog Development. 1996, Pubmed
Shibata, Overexpression of S-adenosylmethionine decarboxylase (SAMDC) in early Xenopus embryos induces cell dissociation and inhibits transition from the blastula to gastrula stage. 1998, Pubmed , Xenbase
Shinga, Early patterning of the prospective midbrain-hindbrain boundary by the HES-related gene XHR1 in Xenopus embryos. 2001, Pubmed , Xenbase
Shinga, Maternal and zygotic expression of mRNA for S-adenosylmethionine decarboxylase and its relevance to the unique polyamine composition in Xenopus oocytes and embryos. 1996, Pubmed , Xenbase
Shiokawa, Occurrence of pre-MBT synthesis of caspase-8 mRNA and activation of caspase-8 prior to execution of SAMDC (S-adenosylmethionine decarboxylase)-induced, but not p53-induced, apoptosis in Xenopus late blastulae. 2005, Pubmed , Xenbase
Shiokawa, Changes in the patterns of RNA synthesis in early embryogenesis of Xenopus laevis. 1989, Pubmed , Xenbase
Shiokawa, Temporal control of gene expression from endogenous and exogenously-introduced DNAs in early embryogenesis of Xenopus laevis. 1994, Pubmed , Xenbase
Shiokawa, Pattern of RNA synthesis in isolated cells of Xenopus laevis embryos. 1967, Pubmed , Xenbase
Shiokawa, Maternal program of apoptosis activated shortly after midblastula transition by overexpression of S-adenosylmethionine decarboxylase in Xenopus early embryos. 2000, Pubmed , Xenbase
Shiokawa, Expression of exogenously introduced bacterial chloramphenicol acetyltransferase genes in Xenopus laevis embryos before the midblastula transition. 1990, Pubmed , Xenbase
Shiratsuchi, Phosphatidylserine-mediated phagocytosis of anticancer drug-treated cells by macrophages. 1999, Pubmed
Shook, Pattern and morphogenesis of presumptive superficial mesoderm in two closely related species, Xenopus laevis and Xenopus tropicalis. 2004, Pubmed , Xenbase
Sible, Zygotic transcription is required to block a maternal program of apoptosis in Xenopus embryos. 1997, Pubmed , Xenbase
Slee, Ordering the cytochrome c-initiated caspase cascade: hierarchical activation of caspases-2, -3, -6, -7, -8, and -10 in a caspase-9-dependent manner. 1999, Pubmed
Stack, Developmentally regulated activation of apoptosis early in Xenopus gastrulation results in cyclin A degradation during interphase of the cell cycle. 1997, Pubmed , Xenbase
Stancheva, Loss of the maintenance methyltransferase, xDnmt1, induces apoptosis in Xenopus embryos. 2001, Pubmed , Xenbase
Takayama, Involvement of caspase-9 in execution of the maternal program of apoptosis in Xenopus late blastulae overexpressed with S-adenosylmethionine decarboxylase. 2004, Pubmed , Xenbase
Tata, Prolactin inhibits both thyroid hormone-induced morphogenesis and cell death in cultured amphibian larval tissues. 1991, Pubmed , Xenbase
Tchang, Stabilization and expression of high levels of p53 during early development in Xenopus laevis. 1993, Pubmed , Xenbase
Thornberry, The caspase family of cysteine proteases. 1997, Pubmed
Wakiyama, mRNA encoding the translation initiation factor eIF-4E is expressed early in Xenopus embryogenesis. 1995, Pubmed , Xenbase
Wallingford, p53 activity is essential for normal development in Xenopus. 1997, Pubmed , Xenbase
Wang, Thyroid hormone-induced gene expression program for amphibian tail resorption. 1993, Pubmed , Xenbase
Woodland, Changes in the polysome content of developing Xenopus laevis embryos. 1974, Pubmed , Xenbase
Wroble, Chk2/Cds1 protein kinase blocks apoptosis during early development of Xenopus laevis. 2005, Pubmed , Xenbase
Yang, Prevention of apoptosis by Bcl-2: release of cytochrome c from mitochondria blocked. 1997, Pubmed
Yang, Beta-catenin/Tcf-regulated transcription prior to the midblastula transition. 2002, Pubmed , Xenbase
Yaoita, Induction of apoptosis and CPP32 expression by thyroid hormone in a myoblastic cell line derived from tadpole tail. 1997, Pubmed , Xenbase
Yasuda, Temporal regulation in the early embryo: is MBT too good to be true? 1992, Pubmed , Xenbase
zur Nieden, Induction of chondro-, osteo- and adipogenesis in embryonic stem cells by bone morphogenetic protein-2: effect of cofactors on differentiating lineages. 2005, Pubmed