Incomplete X chromosome dosage compensation in chorionic villi of human placenta.
- 1 May 1985
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 82 (10), 3390-3394
- https://doi.org/10.1073/pnas.82.10.3390
Abstract
Studies of glucose-6-phosphate dehydrogenase (G6PD) in heterozygous cells from chorionic villi of 5 fetal and 1 newborn placenta show that the locus on the allocyclic X is expressed in many cells of this trophectoderm derivative. Heterodimers were present in clonal populations of cells with normal diploid karyotype and a late replicating X chromosome. The expression of the 2 X chromosomes was unequal, based on ratios of homodimers and heterodimers in clones. Studies of DNA, digested with Hpa II and probed with cloned genomic G6PD sequences, indicate that expression of the locus in chorionic villi is associated with hypomethylation of 3'' CpG clusters. Dosage compensation, at least at the G6PD locus, has not been well established or maintained (or both) in placental tissue. The active X chromosome in these human cells of trophoblastic origin can be either the paternal or maternal one. Paternal X inactivation in extraembryonic lineages is not an essential feature of mammalian X dosage compensation.This publication has 23 references indexed in Scilit:
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