# Functional State of Lampbrush Chromosomes in Early Vitellogenic Oocytes of Hibernating Frogs Rana temporaria

## TL;DR

This paper studies lampbrush chromosomes in hibernating frogs and finds they remain active but at lower levels, with increased transcription when warmed.

## Contribution

The study reveals the functional state of lampbrush chromosomes during hibernation in Rana temporaria oocytes.

## Key findings

- Lampbrush chromosomes retain their morphology during hibernation.
- Transcription on lateral loops is reduced at cold temperatures but increases at room temperature.
- Satellite S1a transcripts are present on lateral loops during hibernation.

## Abstract

Lampbrush chromosomes (LBCs) are a feature of amphibian oocytes and are typically associated with high levels of transcription during active oocyte growth. However, their state during winter hibernation has not been studied. Here, we investigated LBCs in early vitellogenic oocytes (early stage 4) of the grass frog Rana temporaria during winter hibernation. We found that the chromosomes retained their lampbrush morphology, and the phosphorylated form of RNA polymerase II resided on the lateral loops. Transcription on the lateral loops was reduced but detectable at cold conditions and significantly increased when the oocytes were transferred at room temperature. Satellite S1a transcripts were detected at the lateral loops of the chromosomes by RNA FISH. The possible significance of maintaining chromosomes in the lampbrush form during hibernation is discussed.