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

Zybina TG, Zybina EV, Bogdanova MS, Stein GI - Reprod. Biol. Endocrinol. (2003)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky ave, 194064 St, Russia. zybina@mail.cytspb.rssi.ru

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.

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Relationship between ploidy and DNA content in the larger (black circle) and smaller (white circle) GCB in the nuclei with two GCBs in the trophoblast cells of the junctional zone of placenta (a) and seconday giant trophoblast cells (b). DNA content in separate GCBs is expressed in arbitrary units (a.u.).
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Figure 4: Relationship between ploidy and DNA content in the larger (black circle) and smaller (white circle) GCB in the nuclei with two GCBs in the trophoblast cells of the junctional zone of placenta (a) and seconday giant trophoblast cells (b). DNA content in separate GCBs is expressed in arbitrary units (a.u.).

Mentions: Results of measurement of the DNA content in GCBs are presented in Figs. 3,4,5 and in Tables 1,2,3,4. The total amount of DNA in GCBs in nuclei of trophoblast cells have been found to increase proportionally with increase of the ploidy level at both studied stages of embryonal development in the both cell populations (Table 1, 2). This parallel increase takes place in nuclei both with one and with 2–3 GCB. Such proportional increase of the GCB material in the course of polyploidization is also confirmed by a high positive correlation between the DNA content in the nucleus and the total DNA amount in GCB (r = 0.88 and 0.79 for cells of the junctional zone of placenta at the 10th and 14th days pc, respectively). The separate GCBs also shown the increase of the DNA content proportionally to the ploidy level (Fig. 3, 4). The number of GCBs in nuclei of different ploidy somewhat varies. In the trophoblast cells of the placenta junctional zone, a marked increase of the fraction of 8c and 16c nuclei containing 2–3 GCBs was found (Fig. 5a,5c). By contrast, in the secondary giant trophoblast cells the portion of nuclei with 2 GCBs at the 10th day of development was lower than in the 8–16c nuclei in the placenta junctional zone. At the 14th day pc the portion of nuclei with 2 GCBs in the secondary giant trophoblast cells was markedly higher than at the 10th day pc (Fig. 5b,5d).


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

Zybina TG, Zybina EV, Bogdanova MS, Stein GI - Reprod. Biol. Endocrinol. (2003)

Relationship between ploidy and DNA content in the larger (black circle) and smaller (white circle) GCB in the nuclei with two GCBs in the trophoblast cells of the junctional zone of placenta (a) and seconday giant trophoblast cells (b). DNA content in separate GCBs is expressed in arbitrary units (a.u.).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC155541&req=5

Figure 4: Relationship between ploidy and DNA content in the larger (black circle) and smaller (white circle) GCB in the nuclei with two GCBs in the trophoblast cells of the junctional zone of placenta (a) and seconday giant trophoblast cells (b). DNA content in separate GCBs is expressed in arbitrary units (a.u.).
Mentions: Results of measurement of the DNA content in GCBs are presented in Figs. 3,4,5 and in Tables 1,2,3,4. The total amount of DNA in GCBs in nuclei of trophoblast cells have been found to increase proportionally with increase of the ploidy level at both studied stages of embryonal development in the both cell populations (Table 1, 2). This parallel increase takes place in nuclei both with one and with 2–3 GCB. Such proportional increase of the GCB material in the course of polyploidization is also confirmed by a high positive correlation between the DNA content in the nucleus and the total DNA amount in GCB (r = 0.88 and 0.79 for cells of the junctional zone of placenta at the 10th and 14th days pc, respectively). The separate GCBs also shown the increase of the DNA content proportionally to the ploidy level (Fig. 3, 4). The number of GCBs in nuclei of different ploidy somewhat varies. In the trophoblast cells of the placenta junctional zone, a marked increase of the fraction of 8c and 16c nuclei containing 2–3 GCBs was found (Fig. 5a,5c). By contrast, in the secondary giant trophoblast cells the portion of nuclei with 2 GCBs at the 10th day of development was lower than in the 8–16c nuclei in the placenta junctional zone. At the 14th day pc the portion of nuclei with 2 GCBs in the secondary giant trophoblast cells was markedly higher than at the 10th day pc (Fig. 5b,5d).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky ave, 194064 St, Russia. zybina@mail.cytspb.rssi.ru

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.

Show MeSH