RT Journal Article SR Electronic T1 Meiosis in the scorpion Tityus silvestris: new insights into achiasmatic chromosomes JF Biology Open JO Biology Open FD Company of Biologists SP bio040352 DO 10.1242/bio.040352 VO 8 IS 5 A1 de Almeida, Bruno Rafael Ribeiro A1 Noronha, Renata Coelho Rodrigues A1 da Costa, Marlyson Jeremias Rodrigues A1 Nagamachi, Cleusa Yoshiko A1 Pieczarka, Julio Cesar YR 2019 UL http://bio.biologists.org/content/8/5/bio040352.abstract AB Achiasmatic male meiosis in scorpions is characterized by a high frequency of gaps, asynaptic regions and multivalent associations. Here, we performed an immunocytogenetic analysis to investigate recombination, and synapsis and chromatin-remodeling events during meiosis of the scorpion Tityus silvestris. Our results demonstrate that the synaptonemal complex (SC) begins its organization in the zygotene stage and persists until metaphase I. The advancement of the synaptic process is related to the epigenetic modification histone H3 lysine 27 trimethylation (H3K27m3). The distribution and dynamics patterns of variant γH2AX and recombinase Rad51 during achiasmatic meiosis suggests formation and repair of DNA double-strand breaks (DSBs) during early stages of prophase I. The epigenetic modifications, histone H3 lysine 4 trimethylation (H3K4m3) and histone H3 lysine 9 acetylation (H3K9ac), showed a dispersed distribution along the bivalents, suggesting that transcriptional activity is maintained constitutively during prophase I. However, H3K9ac modifications are absent in constitutive heterochromatin carrying the 45S rDNA in pachytene and post-pachytene stages. Collectively, our data demonstrate that T. silvestris exhibits adaptations to the achiasmatic mode, and suggest that epigenetic modifications may act in the regulation of these mechanisms to favor the normal continuation of meiosis in this scorpion.