Halogenated nucleotide labeling of nascent RNAs reveals dynamic transcription in growing pig oocytes

Authors

  • Reza K. Oqani,

    1. Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University
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  • Min Gu Lee,

    1. Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University
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  • Yun Fei Diao,

    1. Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University
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  • Rong Xun Han,

    1. Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University
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  • Dong Il Jin

    Corresponding author
    1. Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University
    • Department of Animal Science & Biotechnology, Research Center for Transgenic Cloned Pigs, Chungnam National University, Daejeon 305-764, Republic of Korea
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Abstract

Background: Germ cells differentiate into oocytes in females and are arrested at the first meiotic prophase. However, during arrest, oocytes undergo a growth phase leading to a dramatic increase in size, which is under control of transcription events. In the current study, we examined the transcriptional activity of growing pig oocytes using an immunocytochemical approach. Our data showed that fluorouridine (FU), a halogenated nucleotide, can be successfully incorporated into synthesizing RNAs and detected using a specific monoclonal antibody. Results: Using this method, we identified dynamic changes in transcriptional activity patterns in growing pig oocytes. Oocytes obtained from small follicles exhibited the highest level of transcription, while at the final phase of growth, transcription was no longer detected. These transcriptional changes were concomitant with chromatin compaction resulting in a tightly packed ring-like chromatin conformation surrounding the nucleolar structure. Also, FU incorporation appeared sensitive to the biochemical manipulation of transcription, because transcriptional inhibitors induced a decrease in signal intensity from FU labeling and transcriptional activation caused an increase in FU signal intensity. Conclusions: Our data collectively support that a direct link exists between chromatin configuration and transcriptional activity in pig oocytes, and support the suitability of FU for studies on transcription-related events in mammalian oocytes. Developmental Dynamics 242:16–22, 2013. © 2012 Wiley Periodicals, Inc.

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