Regeneration is a biological process restoring lost or amputated body parts. The capability of regeneration varies among organisms and the regeneration of the central nervous system (CNS) is limited to specific animals, including the earthworm Perionyx excavatus. Thus, it is crucial to establish P. excavatus as a model system to investigate mechanisms of CNS regeneration. Here, we set up a culture system to sustain the life cycle of P. excavatus and characterize the development of P. excavatus, from embryo to juvenile, based on its morphology, myogenesis and neurogenesis. During development, embryos have EdU-positive proliferating cells throughout the whole body, whereas juveniles maintain proliferating cells exclusively in the head and tail regions, not in the trunk region. Interestingly, juveniles amputated at the trunk, which lacks proliferating cells, are able to regenerate the entire head. In this process, a group of cells, which are fully differentiated, reactivates cell proliferation. Our data suggest that P. excavatus is a model system to study CNS regeneration, which is dependent on the dedifferentiation of cells.

The mitochondrial genome (mitogenome) of Aleochara ( Aleochara ) curtula (Goeze, 1777) (Coleoptera: Staphylinidae) is reported. This mitogenome (GenBank accession no. OL675411) is 16,600 bp in size and consists of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNA). Most PCGs use typical mitochondrial stop codon (TAR) except for cox3 , which uses a single T residue. The A, G, T, and C nucleotide base composition of the mitogenome is 40.61%, 7.66%, 40.34%, and 11.39%, respectively. The phylogenetic analyses recovered the monophyly of Aleocharinae.

Background The family Staphylinidae is the most speciose beetle group in the world. The outbreaks of two staphylinid species, Paederus fuscipes and Aleochara (Aleochara) curtula, were recently reported in South Korea. None of research about molecular markers and genetic diversity have been conducted in these two species. Objective To develop microsatellite markers and analyze the genetic diversity and population structures of two rove beetle species. Methods NGS was used to sequence whole genomes of two species, Paederus fuscipes and Aleochara (Aleochara) curtula. Microsatellite loci were selected with flanking primer sequences. Specimens of P. fuscipes and A. curtula were collected from three localities, respectively. Genetic diversity and population structure were analyzed using the newly developed microsatellite markers. Results The number of alleles ranged 5.727–6.636 (average 6.242) and 2.182–5.364 (average 4.091), expected heterozygosity ranged 0.560–0.582 (average 0.570) and 0.368–0.564 (average 0.498), observed heterozygosity ranged 0.458–0.497 (average 0.472) and 0.418–0.644 (average 0.537) in P. fuscipes and A. curtula, respectively. Population structure indicates that individuals of A. curtula are clustered to groups where they were collected, but those of P. fuscipes are not. Conclusion Population structures of P. fuscipes were shallow. In A. curtula, however, it was apparent that the genetic compositions of the populations are different significantly depending on collection localities.