Macedonian Veterinary Review

Original Scientific Article

Mouse nucleolus-like body supports transcription and enhances processing of rRNA in porcine enucleolated oocytes

Martin Morovic

Frantisek Strejcek *

Michal Benc

Alexandra Rosenbaum Bartkova

Sara Stachovicova

Florina Popovska-Percinic

Monika Dovenska

Jozef Laurincik

Mac Vet Rev 2025; 48 (1): i - vii

10.2478/macvetrev-2025-0011

Received: 05 June 2024

Received in revised form: 28 August 2024

Accepted: 04 September 2024

Available Online First: 10 January 2025

Published on: 20 December 2024

Correspondence: Frantisek Strejcek, fstrejcek@ukf.sk

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Abstract

Fully-grown mammalian oocytes contain morphologically evident but transcriptionally inactive nucleoli called “nucleolus-like bodies” (NLBs). These nuclear structures are essential for early embryonic development. Removing oocyte NLBs (enucleolation) before their activation leads to developmental failure, mainly at the time point of embryonic genome activation. The present study examined the developmental and expression dynamics of embryos derived from intra- (pig) and interspecies (mouse) nucleolus (NLB) transferred porcine oocytes after parthenogenetic activation. Activation of rDNA transcription and pre-rRNA processing in NLB re-injected embryos was observed by real-time qRT-PCR analysis, targeting the expression rates of 45S rRNA and levels of 18S rRNA. Reinjection of NLBs from mouse or porcine GV oocytes into the enucleolated MII stage porcine oocytes supported the embryonic development up to the blastocyst stage after their activation. Intra- and intergeneric NLB transferred embryos demonstrated rDNA transcription initiation at the 8-cell stage, corresponding with the embryonic genome activation in porcine parthenogenetic embryos (control). The measured levels of 18S rRNA in these experimental embryos showed delayed initiation of pre-rRNA processing at the blastocysts stage compared with the control (8-cell stage). However, the porcine embryos with re-injected mouse NLB displayed significantly higher levels of 18S rRNA than the control and experimental intraspecies group. In conclusion, NLBs from different mammal species (mouse) can enhance the quality of enucleolated porcine oocytes and thus support their early embryonic development after activation.

Keywords: nucleolus-like body, oocyte, pig, mouse, nucleolotransfer

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Copyright

© 2025 Morovic M. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Conflict of Interest Statement

The authors declared that they have no potential lict of interest with respect to the authorship and/or publication of this article.

Citation Information

Macedonian Veterinary Review. Volume 48, Issue 1, Pages i-vii, e-ISSN 1857-7415, p-ISSN 1409-7621, DOI: 10.2478/macvetrev-2025-0011