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Time-lapse dynamics of the mouse oocyte chromatin organisation during meiotic resumption.

Belli M, Vigone G, Merico V, Redi CA, Garagna S, Zuccotti M - Biomed Res Int (2014)

Bottom Line: When matured to MII and fertilised, only SN oocytes develop beyond the 2-cell, and reach full term.To give detailed information on the dynamics of the SN or NSN chromatin during meiosis resumption, we performed a 9 hr time-lapse observation.Overall, we described a pathway of transition from the GV to the MII stage that is punctuated of discrete recordable events showing their specificity and occurring with different time kinetics in the two types of oocytes.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie "Lazzaro Spallanzani", Università degli Studi di Pavia, Via Ferrata 9, 27100 Pavia, Italy.

ABSTRACT
In the mammalian oocyte, distinct patterns of centromeres and pericentromeric heterochromatin localisation correlate with the gamete's developmental competence. Mouse antral oocytes display two main types of chromatin organisation: SN oocytes, with a ring of Hoechst-positive chromatin surrounding the nucleolus, and NSN oocytes lacking this ring. When matured to MII and fertilised, only SN oocytes develop beyond the 2-cell, and reach full term. To give detailed information on the dynamics of the SN or NSN chromatin during meiosis resumption, we performed a 9 hr time-lapse observation. The main significant differences recorded are: (1) reduction of the nuclear area only in SN oocytes; (2) ~17 min delay of GVBD in NSN oocytes; (3) chromatin condensation, after GVBD, in SN oocytes; (4) formation of 4-5 CHCs in SN oocytes; (5) increase of the perivitelline space, ~57 min later in NSN oocytes; (6) formation of a rosette-like disposition of CHCs, ~84 min later in SN oocytes; (7) appearance of the MI plate ~40 min later in NSN oocytes. Overall, we described a pathway of transition from the GV to the MII stage that is punctuated of discrete recordable events showing their specificity and occurring with different time kinetics in the two types of oocytes.

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Time-lapse imaging from 128 to 216 minutes of oocyte culture. (a) SN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Arrow in (f') enlargement, large CHC; arrowhead, small CHC. (b) NSN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Bar: 40 μm.
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fig2: Time-lapse imaging from 128 to 216 minutes of oocyte culture. (a) SN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Arrow in (f') enlargement, large CHC; arrowhead, small CHC. (b) NSN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Bar: 40 μm.

Mentions: Under UV light, from the 128 min onwards, we recorded a progressive partial decondensation of the CHCs (Figure 2(a) (b'–m'); see enlargement: arrow, large CHC; arrowhead, small CHC; Additional file 4). In NSN oocytes, following the first 120 min of culture when chromatin organisation does not change, chromosomes appear abruptly (139.2 ± 20.9 min of culture (Table 1; Figure 2(b) (b') and enlargement), much earlier than in SN oocytes (see below) and assume a “rosette-like” organisation (Figure 2(b) (e') and enlargement) that is maintained up to the end of this recording time segment (Additional file 5).


Time-lapse dynamics of the mouse oocyte chromatin organisation during meiotic resumption.

Belli M, Vigone G, Merico V, Redi CA, Garagna S, Zuccotti M - Biomed Res Int (2014)

Time-lapse imaging from 128 to 216 minutes of oocyte culture. (a) SN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Arrow in (f') enlargement, large CHC; arrowhead, small CHC. (b) NSN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Bar: 40 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016838&req=5

fig2: Time-lapse imaging from 128 to 216 minutes of oocyte culture. (a) SN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Arrow in (f') enlargement, large CHC; arrowhead, small CHC. (b) NSN oocyte, (a–m) bright field; (a'–m') UV fluorescence. Bar: 40 μm.
Mentions: Under UV light, from the 128 min onwards, we recorded a progressive partial decondensation of the CHCs (Figure 2(a) (b'–m'); see enlargement: arrow, large CHC; arrowhead, small CHC; Additional file 4). In NSN oocytes, following the first 120 min of culture when chromatin organisation does not change, chromosomes appear abruptly (139.2 ± 20.9 min of culture (Table 1; Figure 2(b) (b') and enlargement), much earlier than in SN oocytes (see below) and assume a “rosette-like” organisation (Figure 2(b) (e') and enlargement) that is maintained up to the end of this recording time segment (Additional file 5).

Bottom Line: When matured to MII and fertilised, only SN oocytes develop beyond the 2-cell, and reach full term.To give detailed information on the dynamics of the SN or NSN chromatin during meiosis resumption, we performed a 9 hr time-lapse observation.Overall, we described a pathway of transition from the GV to the MII stage that is punctuated of discrete recordable events showing their specificity and occurring with different time kinetics in the two types of oocytes.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie "Lazzaro Spallanzani", Università degli Studi di Pavia, Via Ferrata 9, 27100 Pavia, Italy.

ABSTRACT
In the mammalian oocyte, distinct patterns of centromeres and pericentromeric heterochromatin localisation correlate with the gamete's developmental competence. Mouse antral oocytes display two main types of chromatin organisation: SN oocytes, with a ring of Hoechst-positive chromatin surrounding the nucleolus, and NSN oocytes lacking this ring. When matured to MII and fertilised, only SN oocytes develop beyond the 2-cell, and reach full term. To give detailed information on the dynamics of the SN or NSN chromatin during meiosis resumption, we performed a 9 hr time-lapse observation. The main significant differences recorded are: (1) reduction of the nuclear area only in SN oocytes; (2) ~17 min delay of GVBD in NSN oocytes; (3) chromatin condensation, after GVBD, in SN oocytes; (4) formation of 4-5 CHCs in SN oocytes; (5) increase of the perivitelline space, ~57 min later in NSN oocytes; (6) formation of a rosette-like disposition of CHCs, ~84 min later in SN oocytes; (7) appearance of the MI plate ~40 min later in NSN oocytes. Overall, we described a pathway of transition from the GV to the MII stage that is punctuated of discrete recordable events showing their specificity and occurring with different time kinetics in the two types of oocytes.

Show MeSH
Related in: MedlinePlus