Chromatin-based regulation of gene expression.

Research focuses on the biology of long-lived plants, different from Arabidopsis, tomato or grass species widely studied. In the European larch, the diplotene stage lasts approximately five months, and it is possible to divide it into several substages and observe each of them in detail. Our studies aim to examine whether the synthesis and maturation of mRNA accompany chromatin relaxation during the diplotene. The results reveal a correlation between chromatin condensation and transcriptional activity (Kołowezo-Lubnau et al., 2015). We also found decreasing amount of mRNA synthesis in the consecutive diffusion stages. During the early diffusion stages, mRNA is intensively synthesized. In the nuclei, large amounts of RNA polymerase II and high levels of snRNPs were observed. In the late diffusion stages, the synthesized mRNA is not directly subjected to translation, but it is stored in the nucleus and later transported to the cytoplasm and translated. In the last diffusion stage, the poly(A) RNA level is low, but that of splicing factors is still high. It appears that the mRNA synthesized in the early stages is used during the diplotene stage and is not transmitted to dyad and tetrads. In contrast, splicing factors accumulate and are most likely transmitted to the dyad and tetrads, used after intense transcription resumption.