RNA synthesis in pig follicular oocytes. Autoradiographic and cytochemical study

Motlı́k, Jan; Kopečný, V.; Trávník, Pavel; Pivko, J.

doi:10.1111/j.1768-322x.1984.tb00270.x

Cited by 53 publications

(23 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ability to resume meiosis (i.e., to undergo germinal vesicle breakdown [GVBD]) is acquired by porcine oocytes when they approach the end of the growth phase in antral follicles greater than 0.8 mm in diameter, which is well before they acquire the capacity for completing meiotic maturation to metaphase II at a follicular diameter of greater than 2 mm [8,9]. Acquisition of full meiotic competence coincides with a markedly decreased rate of transcription in the oocyte and a complete inactivation of the ribosomal RNA (rRNA) synthesis in the nucleolus of the gamete [10,11].…”

Section: Introductionmentioning

confidence: 99%

Regulation of Ribosomal RNA Synthesis During the Final Phases of Porcine Oocyte Growth

Bjerregaard¹,

Wrenzycki²,

Philimonenko

et al. 2003

Biology of Reproduction

View full text Add to dashboard Cite

In porcine oocytes, acquisition of meiotic competence coincides with a decrease of general transcriptional activity at the end of the oocyte growth phase and, specifically, of ribosomal RNA (rRNA) synthesis in the nucleolus. The present study investigated the regulation of rRNA synthesis during porcine oocyte growth. Localization and expression of components involved in regulation of the rRNA synthesis (the RNA polymerase I-associated factor PAF53, upstream binding factor [UBF], and the pocket proteins p130 and pRb) were assessed by immunocytochemistry and semiquantitative reverse transcription-polymerase chain reaction and correlated with ultrastructural analysis and autoradiography following [3H]uridine incubation in growing and fully grown porcine oocytes. In addition, meiotic resumption, ultrastructure, and expression of p130, UBF, and PAF53 were analyzed in growing and fully grown porcine oocytes cultured with 100 microM butyrolactone I (BL-I), a potent inhibitor of cyclin-dependent kinases, to gain insight concerning the regulation of rRNA transcription during meiotic arrest. Immunocytochemical analysis demonstrated that p130 became colocalized with UBF and PAF53 and that the intensity of the PAF53 labeling decreased toward the end of the oocyte growth phase. These data suggest that the decrease in rRNA synthesis is regulated through inhibition of UBF by p130 as well as by decreased availability of PAF53. Moreover, expression of mRNA encoding PAF53 was decreased at the end of the oocyte growth phase. At the morphological level, these events coincided with inactivation of the nucleolus, as visualized by the transformation of the fibrillogranular nucleolus to an electron-dense fibrillar sphere with remnants of the fibrillar centers at the surface. Meiotic inhibition with 100 microM BL-I had a detrimental effect on the ability of porcine oocytes to resume meiosis and on nucleolus morphology, resulting in a lack of RNA synthetic capability as the fibrillar components, where rRNA transcription and initial processing occur, condensed or even disintegrated.

show abstract

Section: Introductionmentioning

confidence: 99%

Regulation of Ribosomal RNA Synthesis During the Final Phases of Porcine Oocyte Growth

Bjerregaard¹,

Wrenzycki²,

Philimonenko

et al. 2003

Biology of Reproduction

View full text Add to dashboard Cite

show abstract

“…Unlike somatic cells, fully grown mammalian oocytes are characterized by repressed transcription (Motlik et al 1984, Fair et al 1996, Bouniol-Baly et al 1999, De La Fuente & Eppig 2001, Bjerregaard & Maddox-Hyttel 2004, and oocytes thus cannot be manipulated by cDNA transfection. Given the ubiquitous and crucial functions of clathrin, clathrin knockout animals have not been generated, and conditional knockout systems for clathrin in oocytes are not available.…”

Section: Gfp-injected Oocytes (Gfp; 58 and 50 Oocytes In A And B Rementioning

confidence: 99%

Clathrin is essential for meiotic spindle function in oocytes

Hölzenspies

Colenbrander²,

Romijn³

et al. 2010

Reproduction

View full text Add to dashboard Cite

In the mammalian ovary, oocytes are arrested at prophase of meiosis I until a hormonal stimulus triggers resumption of meiosis. During the subsequent meiotic maturation process, which includes completion of the first meiotic division and formation of the second metaphase spindle, oocytes acquire competence for fertilization. Recently, it was shown that clathrin, a cytosolic protein complex originally defined for its role in intracellular membrane traffic, is also involved in the stabilization of kinetochore fibers in mitotic spindles of dividing somatic cells. However, whether clathrin has a similar function in meiotic spindles in oocytes has not been investigated previously. Our results show that endogenous clathrin associates with the meiotic spindles in oocytes. To study the function of clathrin during meiotic maturation, we microinjected green fluorescent protein-tagged C-terminal and N-terminal dominant-negative clathrin protein constructs into isolated porcine oocytes prior to in vitro maturation. Both protein constructs associated with meiotic spindles similar to endogenous clathrin, but induced misalignment and clumping of chromosomes, occurrence of cytoplasmic chromatin and failure of polar body extrusion. These data demonstrate that clathrin plays a crucial role in meiotic spindle function in maturing oocytes, possibly through spindle stabilization.

show abstract

“…Oocytes from peripheral follicles visible on the ovarian surface were found to give rise to superior rates of meiotic maturation irrespective of their diameter. Increasing meiotic competence during oocyte growth has previously been indirectly demonstrated in cattle (Fuhrer et al 1989), swine Motlik et al 1984) and goat (de Schmedt et al 1994) where a substantial improvement of the meiotic competence of the oocyte occurs with increasing follicle size. Moreover, in all species, full meiotic competence appears to be acquired at a follicle size of about 3 mm, which at least in cattle corresponds to an oocyte diameter of about 1 10 mm (Fair et al 1995).…”

Section: Achievement Of Oocyte Competence During Oocyte Growthmentioning

confidence: 91%