Quantitative investigation of reproduction of gonosomal condensed chromatin during trophoblast cell polyploidization and endoreduplication in the east-european field vole Microtus rossiaemeridionalis

Abstract

Simultaneous determinations of DNA content in cell nuclei and condensed chromatin bodies formed by heterochromatized regions of sex chromosomes (gonosomal chromatin bodies, GCB) have been performed in two trophoblast cell populations of the East-European field vole Microtus rossiaemeridionalis: in the proliferative population of trophoblast cells of the junctional zone of placenta and in the secondary giant trophoblast cells. One or two GCBs have been observed in trophoblast cell nuclei of all embryos studied (perhaps both male and female). In the proliferative trophoblast cell population characterized by low ploidy levels (2–16c) and in the highly polyploid population of secondary giant trophoblast cells (32–256c) the total DNA content in GCB increased proportionally to the ploidy level. In individual GCBs the DNA content also rose proportionally to the ploidy level in nuclei both with one and with two GCBs in both trophoblast cell populations. Some increase in percentage of nuclei with 2–3 GCBs was shown in nuclei of the placenta junctional zone; this may be accounted for by genome multiplication via uncompleted mitoses. In nuclei of the secondary giant trophoblast cells (16–256c) the number of GCBs did not exceed 2, and the fraction of nuclei with two GCBs did not increase, which suggests the polytene nature of sex chromosomes in these cells. In all classes of ploidy the DNA content in trophoblast cell nuclei with the single GCB was lower than in nuclei with two and more GCBs. This can indicate that the single GCB in many cases does not derive from fusion of two GCBs. The measurements in individual GCBs suggest that different heterochromatized regions of the X- and Y-chromosome may contribute in GCB formation.

Cell Cycle Modification in Trophoblast Cell Populations in the Course of Placenta Formation

“…The natural chromosome markers -nucleoli, Barr bodies (inactivated X-chromosomes) and condensed heterochromatin regions of polytene chromosomes -are distributed into nuclear fragments in accordance with ploidy their level (Zybina, 1986;Zybina, Zybina, 1996). The whole-genome chromosome distribution into the nuclear fragment is confirmed by the use of another natural chromosome marker of the interphase nucleus, i.e., gonosomal chromatin bodies (GCB, Zybina et al, 2003Zybina et al, , 2005. Cytophotometrical measurement of DNA content in the nuclei, nuclear fragments, and simultaneously in the gonosomal chromatin bodies was made in the SGTCs of field vole M. rossiaemeridionalis.…”

“…The level of ploidy clearly correlates with the ability of cells to invade endometrium, to lyse and to phagocytose partly its tissues in the course of embryo implantation. Beginning from the onset of differentiation, the primary and secondary giant trophoblast cells undergo a series of endoreduplication cycle reaching very high ploidy level -512c-1024c in rat and mouse (Zybina, Mosjan, 1967;Barlow, Sherman, 1972 ;Zybina, Zybina, 1996; 2048c and 16384c in the field vole (Zybina et al, 1975;Zybina et al, 2003;Zybina et al, 2009). The cells have the non-classical polytene chromosomes and can combine cell replication with the invasive and phagocytic activity (Zybina, Zybina, 2005).…”

Maternal-fetal interfaces transcriptome changes associated with placental insufficiency and a novel gene therapy intervention

“…Non-proliferative daughter cells leave the cell columns due to proliferation pressure, and start migrating in a selfsecreted extracellular matrix [32]. Invasion of the maternal uterine tissue proceeds, stopped by either apoptosis or by the generation of multinucleated giant cells through polyploidization [33][34][35]. The patterns of trophoblast invasion in the guinea pig are similar to those shown in the degu placenta, where invaded maternal spiral arteries can be distinguished from non-invaded arteries by the presence of cytokeratin positive trophoblast versus SMA positive endothelium [29].…”

Genome Modifications Involved in Developmental Programs of the Placental Trophoblast

“…In this case, division is achieved without complete chromosome condensation and their arrangement in metaphase plate, spindle formation and poleward chromosome movement. DNA content as well as nucleoli, heterochromatin and gonosomal chromatin bodies distributed into "subnuclei" according to their ploidy levels [3,[27][28][29][30]. By now, it is possible to consider it as variant of so called "polyploidy cycle" [31][32][33] that implies alternation of diploid and polyploid state in a cell lineage.…”