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Liana Bosco , Giovanni Ruvolo , Roberto Chiarelli , Maria Agnello , Maria Carmela Roccheri (2015). Apoptotic Analysis of Cumulus Cells for the Selection of Competent Oocytes to Be Fertilized by Intracytoplasmic Sperm Injection (ICSI). Journal of Cells, 1(1): 8-19. DOI: 10.18488/journal.97/2015.1.1/18.104.22.168
Oocyte quality is one of the main factors for the success of in vitro fertilization protocols. Apoptosis is known to affect oocyte quality and may impair subsequent embryonic development and implantation. The aim of this study was to investigate the apoptosis rate of single and pooled cumulus cells of cumulus cell–oocyte complexes (COCs), as markers of oocyte quality, prior to intracytoplasmatic sperm injection (ICSI).We investigated the apoptosis rate by TUNEL assay (DNA fragmentation) and caspase-3 immunoassay of single and pooled cumulus cells of COCs. The results showed that DNA fragmentation in cumulus cells was remarkably lower in patients who achieved a pregnancy than in those who did not. Cumulus cell apoptosis rate could be a marker for the selection of the best oocytes to be fertilized by intracytoplasmatic sperm injection.
This study is one of very few studies which have investigated the apoptosis rate by TUNEL assay and caspase-3 immunoassay of single and pooled human cumulus cells of COCs. The apoptosis rate could be a marker for the selection of the best oocytes to be fertilized by intracytoplasmatic sperm injection.
Gene Expression during the Cell Cycle: Obfuscation of Original Cell-Cycle Gene Expression Data by Normalization
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Stephen Cooper (2015). Gene Expression during the Cell Cycle: Obfuscation of Original Cell-Cycle Gene Expression Data by Normalization. Journal of Cells, 1(1): 1-7. DOI: 10.18488/journal.97/2015.1.1/22.214.171.124
Normalization of raw data on gene expression during the cell cycle obscures the original experimental data and makes it appear as if all genes have the same numerical level of cyclical expression. Results that would not support gene expression because of minimal variations thus appear, after normalization, to be stronger than they actually are. Consideration of the effect of normalization raises critical questions about many experiments on the cell cycle dependent variation of gene expression—that is, proposed cyclical changes in mRNA content—during the cell cycle.
This paper demonstrates that normalization makes minimal variations appear much stronger than they are in the raw data, and thus one should be skeptical of some published results proposing cell-cycle specific gene expression.