The effects of fetal calf serum (FCS)

The aim of this study was to try establishing mouse ES cell lines from the early developmental stage. Fifty-two uncompacted 8-cell stage embryos were dissociated and single blastomeres were seeded on primary embryonic fibroblasts in DMEM/F12 completed with 10% foetal calf serum, 10% new born calf serum. 10(-4) M beta-mercaptoethanol. After approximately 5 days of culture, multiple cell clones exhibiting stem cell morphology grew out and were dissociated. One cell line was established (MSB1) and characterised. The karyotype and the G-banding revealed a male diploid cell line. MSB1 cells were injected into syngenic mice and produced teratocarcinomas. Detailed histological examination of the tumours showed a great variety of cell types including representatives of all three primary germ layers. Several nests of undifferentiated stem cells were also present. Microinjections of MSB1 cells into 52 blastocysts produced 2 chimeras, 1 male and 1 female. These results demonstrate that a highly pluripotents ES cell line can be derived from 8-cell stage mouse embryos. However, the male chimera appeared sterile. More experiments would thus be necessary to prove that the cell line obtained is capable to colonise the germ line.

Glucose metabolism of the bovine embryo is low during the first cleavages and increases sharply after the major resumption of the genome (8-16 cells). The mRNA level for genes involved in glucose metabolism was tested by RT-PCR on individual oocytes and embryos at different stages of development. These genes were: glucose transport GLUT-1, hexokinase (HK), glucose-6-phosphate-dehydro-genase (G6PDH), and glucose-phosphate-isomerase (GPI); actin was used as a reference transcript. RT-PCR results revealed three types of oocytes or embryos: positive with a PCR signal for each transcript considered , nul with no signal for any transcript, and heterogeneous with a PCR signal for some transcripts and none for others. The number of nul and heterogeneous samples was higher for slow than for fast-cleaving embryos (81% vs. 36%), and the proportion of positive embryos increased significantly at the 16-cell and morula stages (P , 0.002), suggesting a correlation between mRNA content and developmental capacity. In positive embryos, GLUT-1 mRNA level was reduced by half during maturation and fertilization. Actin and hexoki-nase mRNA levels decreased during the first cleavages, but significantly increased at the 16-cell and morula stages, respectively. GPI transcript remained stable throughout development, whereas there was a significant rise for G6PDH at the 4-cell stage, perhaps due to a polyadenylation process. Finally, the absence or decrease in intensity of several transcripts at the blastocyst stage suggests suboptimal culture conditions. Mol. Re-prod. Dev. 48:216-226, 1997. r 1997 Wiley-Liss, Inc.

Glucose metabolism of the bovine embryo is low during the first cleavages and increases sharply after the major resumption of the genome (8–16 cells). The mRNA level for genes involved in glucose metabolism was tested by RT‐PCR on individual oocytes and embryos at different stages of development. These genes were: glucose transport GLUT‐1, hexokinase (HK), glucose‐6‐phosphate‐dehydrogenase (G6PDH), and glucose‐phosphate‐isomerase (GPI); actin was used as a reference transcript. RT‐PCR results revealed three types of oocytes or embryos: positive with a PCR signal for each transcript considered, nul with no signal for any transcript, and heterogeneous with a PCR signal for some transcripts and none for others. The number of nul and heterogeneous samples was higher for slow than for fast‐cleaving embryos (81% vs. 36%), and the proportion of positive embryos increased significantly at the 16‐cell and morula stages (P < 0.002), suggesting a correlation between mRNA content and developmental capacity. In positive embryos, GLUT‐1 mRNA level was reduced by half during maturation and fertilization. Actin and hexokinase mRNA levels decreased during the first cleavages, but significantly increased at the 16‐cell and morula stages, respectively. GPI transcript remained stable throughout development, whereas there was a significant rise for G6PDH at the 4‐cell stage, perhaps due to a polyadenylation process. Finally, the absence or decrease in intensity of several transcripts at the blastocyst stage suggests suboptimal culture conditions. Mol. Reprod. Dev. 48:216–226, 1997. © 1997 Wiley‐Liss, Inc.

No abstract