Disease relevance of Blastomeres

• 4. Streptomyces subtilisin inhibitor, SSI (0.1%), a specific protease inhibitor for subtilisin-type serine proteases, significantly suppressed (50%) neural induction of the ectodermal blastomere, a4-2, by contact with the chordamesodermal blastomere, A4-1 [1].
• Efficiency of polymerase chain reaction assay for cystic fibrosis in single human blastomeres according to the presence or absence of nuclei [2].
• Full-term development occurred when nuclei from mouse embryonic stem (ES) cells, synchronized in metaphase with nocodazole, were fused with enucleated oocytes or nuclei of reconstituted eggs and again fused with the enucleated blastomeres of fertilized two-cell embryos using inactivated Sendai virus [3].
• Preimplantation diagnosis of alpha-thalassemia by blastomere aspiration and polymerase chain reaction: preliminary experience [4].
• Preimplantation genetic diagnosis for aneuploidy screening (PGD-AS), performed by polar body or blastomere analysis, is used in infertile patients treated with assisted reproduction technologies, especially in those with a poor prognosis, e.g. repeated IVF failure, advanced maternal age, or recurrent spontaneous abortion [5].

High impact information on Blastomeres

• Here, we describe the discovery of a novel Wnt pathway component, Wntless (Wls/Evi), and show that it is required for Wingless-dependent patterning processes in Drosophila, for MOM-2-governed polarization of blastomeres in C. elegans, and for Wnt3a-mediated communication between cultured human cells [6].
• We find that pal-1 activity is sequentially restricted to this blastomere [7].
• By contrast, glp-1 mRNA is present in all blastomeres until the 8-cell stage [8].
• Ectopic expression of gsc mRNA in ventral blastomeres as well as overexpression of gsc in dorsal blastomeres leads to cell movement toward the anterior of the embryo [9].
• The pie-1 and mex-1 genes and maternal control of blastomere identity in early C. elegans embryos [10].

Biological context of Blastomeres

• In addition, the beta-galactosidase reporter is expressed as early as the 28 cell stage of embryogenesis in specific blastomeres prior to their clonal commitment to body wall muscle [11].
• Furthermore, when injected intracellularly into uncleaved embryos or into selected blastomeres, antibodies to the cytoplasmic domain of integrin beta 1 subunit produce a reversible inhibition of FN-fibril formation that follows early cell lineages and cause delays in development [12].
• (iii) No role for ploidy: the mode of parental-specific expression of Snrpn and Igf2r in normal diploid ova was unchanged in individual blastomeres of triploid and tetraploid ova [13].
• Reducing inositol lipid hydrolysis, Ins(1,4,5)P3 receptor availability, or Ca2+ gradients lengthens the duration of the cell cycle in Xenopus laevis blastomeres [14].
• These findings indicate that a different Ca2+-dependent cell adhesion molecule, perhaps another member of the cadherin gene family, is responsible for the Ca2+-dependent adhesion between cleavage stage Xenopus blastomeres [15].

Anatomical context of Blastomeres

• Monoallelic expression of Snrpn was observed in each blastomere at the 4-cell stage, demonstrating that the germ line, which exhibits biallelic expression of imprinted genes, must be derived from cells in which imprinting was once manifest [16].
• In contrast, blastomeres treated with cycloheximide for longer periods (3-6 h) contained numerous microtubule asters and MTOCs [17].
• When the mutant receptor lacking the putative serine/threonine kinase domain was expressed in ventral blastomeres of Xenopus embryos, these blastomeres were respecified to dorsal mesoderm, eventually resulting in the formation of a secondary body axis [18].
• Oocytes lacking E-cadherin, or expressing a truncated allele of beta-catenin without the N-terminal part of the protein, give rise to embryos whose blastomeres do not adhere [19].
• The incidence and organization of cytokeratin filaments increased during the morula stage, although individual blastomeres varied in their content of assembled filaments [20].

Associations of Blastomeres with chemical compounds

• In the 2-cell, 4-cell and precompaction 8-cell embryos, cytoplasmic bridges between sister blastomeres were responsible for ionic coupling and the transfer of injected fluorescein as well as the transfer of injected horseradish peroxidase.In contrast, no communication was observed between blastomeres from different sister pairs [21].
• DESIGN: DNA analysis for the IVS 4 + 4 A-->T (adenine to thymine) mutation in the FA complement C (FANCC) gene in single blastomeres, obtained by biopsy of embryos, to identify genetic status and HLA markers of each embryo before intrauterine transfer [22].
• Eggs and blastomeres also die in this way when treated with STS and CHX, although they are less sensitive to this treatment than trophectoderm or inner cell mass cells whose sensitivity resembles that of other developing cells [23].
• We further investigated the effect of reducing any [Ca2+]i gradients by microinjecting dibromo-BAPTA into the blastomere [14].
• Lithium evokes expression of vegetal-specific molecules in the animal blastomeres of sea urchin embryos [24].

Gene context of Blastomeres

• We propose that maternally provided pie-1(+) and mex-1(+) gene products may function in the early embryo to localize or regulate factors that determine the fate of the MS blastomere [10].
• We propose that the maternally expressed skn-1 gene product acts to specify the fate of the EMS blastomere [25].
• Biallelic expression of Igf2r was observed in single blastomeres, discounting the possibility of random allelic inactivation at this stage [16].
• We have isolated a temperature-sensitive mutation in Caenorhabditis elegans cdk-7 and have used it to analyze the role of cdk-7 in embryonic blastomeres, where cell cycle progression is independent of transcription [26].
• We find that the Caudal-related homeobox factor PAL-1 can activate hlh-1 in blastomeres that either lack POP-1/TCF or that have down-regulated POP-1/TCF in response to Wnt/MAP kinase signaling [27].

Analytical, diagnostic and therapeutic context of Blastomeres

• Microinjection of the mRNA encoding a catalytically inactive form of rat GSK-3 beta into a ventrovegetal blastomere of eight-cell embryos caused ectopic formation of a secondary body axis containing a complete set of dorsal and anterior structures [28].
• Immunofluorescence analysis revealed assembled cytokeratin filaments in some 8-cell blastomeres, but not at earlier stages [29].
• When we assessed early expression of the erythropoietic gene gata-1 in transplant recipients, we found that mutant blastomeres were as likely as wild-type blastomeres to give rise to gata-1-expressing cells in a wild-type host [30].
• In the present study, injection of synthetic mRNA for synaptophysin into one of the early blastomeres of a Xenopus embryo resulted in elevated synaptophysin expression in 1 and 2 d embryos and in cultured spinal neurons derived from the injected blastomere, as shown by immunocytochemistry [31].
• Our aim was to detect the patterns and levels of two messenger ribonucleic acids [mRNAs; beta-actin and interleukin-1 receptor type I (IL-1R tI)] in single human blastomeres by RT-nested PCR and to compare possible variations in the gene expression both between different embryos and in multiple blastomeres within the same embryo [32].

References