Primitive Erythropoiesis in Early Chick Embryogenesis

Weintraub, Harold; Campbell, Graham Le M.; Holtzer, H.

doi:10.1083/jcb.50.3.652

Cited by 100 publications

(12 citation statements)

References 37 publications

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“…We observed that lengths of S and M phases, as well as the length of the G1 phase later, increase after MBT and can be expressed as linear functions of cell cycle time, although in our observations lengths of the G2 phase became randomly variable. The results agree with the previous cytological observations of fixed embryonic cell populations in various animals, which showed that statistically calculated average lengths of cell cycle phases are expressed as linear functions of cell cycle time which increase as embryos develop (Brugal 1971; Weintraub et al . 1971; Kato 1975; Dan et al .…”

Section: Discussionsupporting

confidence: 92%

Midblastula transition (MBT) of the cell cycles in the yolk and pigment granule‐free translucent blastomeres obtained from centrifuged Xenopus embryos

et al. 2005

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We obtained translucent blastomeres free of yolk and pigment granules from Xenopus embryos which had been centrifuged at the beginning of the 8-cell stage with cellular integrity. They divided synchronously regardless of their cell size until they had decreased to 37.5 µm in radius; those smaller than this critical size, however, divided asynchronously with cell cycle times inversely proportional to the square of the cell radius after midblastula transition (MBT). The length of the S phase was determined as the time during which nuclear DNA fluorescence increased in Hoechst-stained blastomeres. When the cell cycle time exceeded 45 min, S and M phases were lengthened; when the cell cycle times exceeded 70 min, the G2 phase appeared; and after cell cycle times became longer than 150 min, the G1 phase appeared. Lengths of G1, S and M phases increased linearly with increasing cell cycle time. Enhanced green fluorescent protein (EGFP)-tagged proliferating cell nuclear antigen (PCNA) expressed in the blastomeres appeared in the S phase nucleus, but suddenly dispersed into the cytoplasm at the M phase. The system developed in this study is useful for examining the cell cycle behavior of the cell cycle-regulating molecules in living Xenopus blastomeres by fluorescence microscopy in real time.

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Section: Discussionsupporting

confidence: 92%

Midblastula transition (MBT) of the cell cycles in the yolk and pigment granule‐free translucent blastomeres obtained from centrifuged Xenopus embryos

et al. 2005

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“…2) and the cell cycle time here measured are fairly close (12 hr and 9 hr, respectively), it is likely that most of the erythroid cells are in cycle during day 1 .5-3 .5 . A lengthening of cell cycle times in the primitive cell series as the cells become more mature has been described in ovo (Weintraub, et al ., 1971) . Cell cycle time by thymidine ,3H pulse using de-embryonated chick blastoderms, six to nine somites .…”

Section: Cell Cycle Time Of Erythroid Cells In Early Culturementioning

confidence: 94%

Developmental Changes of Erythropoiesis in Cultured Chick Blastoderms

Hagopian

Ingram

1971

The Journal of Cell Biology

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The erythropoietic area of very early chick embryos was cultured as a tissue for up to nine days to study the changes in red cell type and hemoglobin type, the cell cycle time, the cell population kinetics, and the DNA synthetase activity of these cells . It was found that the area vasculosa without the participation of the embryo proper contained the information and the timing mechanism required to produce not only the early primitive erythroid cell population, but also in due course, the later definitive cell type, each with its appropriate hemoglobin types . Also the precursors of the definitive cell type are active in DNA synthesis and therefore are probably in cycle very early in the culture period .

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“…Rat kangaroo (PtK.>) cells were maintained in F15 medium with 10% fetal calf serum and the same antibiotics used for the mouse cell lines. Erythroid cells were obtained from chick embryos as described elsewhere Weintraub et al, 1971). The first 24 h are designated day 0, 24-48 h as day 1, etc.…”

Section: ¡Materials and Methodsmentioning

confidence: 99%

Investigation of the determinants of nuclear pore number

Maul

Deaven

Freed

et al. 1980

Cytogenet Genome Res

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To assess the functional significance of nuclear pore complexes, we have investigated whether the number of pores per nucleus is determined by such factors as the nuclear volume, nuclear surface area, DNA content, or aspects of nuclear activity. Comparisons were made between cell types chosen to permit observation of differences in nuclear pore number as a function of differences in the other qualities measured. The number of nuclear pores was determined by freeze-etching and measurements of nuclear surface and nuclear volume by electron and light microscopy. Pairs of cell strains in culture that contained different numbers of chromosome sets were investigated to examine the relation of pore number to total DNA content. Tetraploid cells of the rat kangaroo (Potorous tridactylus) have almost exactly twice the number of pores found in the parental diploid strain. However, the pore number in diploid grassfrog (Rana pipiens) cells was only 65% greater than in the parental haploid cells. In addition, a polyploid series of nucleated RBC had a 62% pore number increase with each successive increase in ploidy. Diploid cell strains from the canyon mouse (Peromyscus crinitus) and from the cactus mouse (P. eremicus) were compared to test whether a difference reflecting the 36% additional DNA in cells of the latter, associated with extra heterochromatin, existed. Although both were found to have the same number of pores and nuclear surface area, the cells differed in nuclear volume. These observations suggest that the number of nuclear pores is independent of the total amount of nuclear DNA, the nuclear surface area (and, thus, presumably the fraction of DNA that is bound to the nuclear membrane), the nuclear volume, and the size of the genome. Rather, the number of nuclear pores appears to be associated with some aspect of nuclear metabolic activity, e.g., transcriptional capacity or release of products to the cytoplasm. Further evidence for such a view comes from studies of chick embryo erythroblasts. In these, nuclear pore number was found to be lower in association with the decreasing nuclear transcriptional activity and longer generation times that characterize the successive cell divisions leading to the fully differentiated state. The number of pore complexes reconstructed in the last cell cycles declined in a manner consistent with reutilization of previously formed pores in the absence of new pore synthesis. Challenging this interpretation is the increase in pore number at lower metabolic activity when Xenopus laevis cells are grown at different temperatures. The speculation that pore complexes have a longer half-life in cooler grown Xenopus cells could resolve the discrepancy.

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Primitive Erythropoiesis in Early Chick Embryogenesis

Cited by 100 publications

References 37 publications

Midblastula transition (MBT) of the cell cycles in the yolk and pigment granule‐free translucent blastomeres obtained from centrifuged Xenopus embryos

Midblastula transition (MBT) of the cell cycles in the yolk and pigment granule‐free translucent blastomeres obtained from centrifuged Xenopus embryos

Developmental Changes of Erythropoiesis in Cultured Chick Blastoderms

Investigation of the determinants of nuclear pore number

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