No abstract

Ki, J-S., Hwang, D-S., Shin, K., Yoon, W. D., Lim, D., Kang, Y. S., Lee, Y., and Lee, J-S. 2008. Recent moon jelly (Aurelia sp.1) blooms in Korean coastal waters suggest global expansion: examples inferred from mitochondrial COI and nuclear ITS-5.8S rDNA sequences. – ICES Journal of Marine Science, 65: 443–452. The moon jelly Aurelia was found recently in Korean coastal environments, and its dense blooms caused economic losses for fisheries and power plants. The species is tentatively recognized as Aurelia aurita; yet, its identity and origin remain elusive. To find reliable molecular evidence for its identity, we determined the DNA sequence of the mitochondrial cytochrome c oxidase subunit I gene and nuclear ITS-5.8S rDNA of specimens collected from different Korean locations. We compared the nuclear and mitochondrial DNA data among specimens and demonstrated that all Korean Aurelia have an identical genotype. BLAST searches demonstrated that the Korean Aurelia matched the previously designated Aurelia sp.1. Parsimony and relevant phylogenetic analyses of the genus Aurelia demonstrated that the genotypes of Korean, Japanese, and Californian Aurelia sp.1 were nearly identical (>99.6% similarity), whereas they were significantly different (<84.1% similarity) from other Aurelia. This suggests that Aurelia sp.1, which occur in the three regions, are descendants of a single population and may have dispersed from one location. However, the dispersal time and origin of Aurelia sp.1 still remain uncertain.

No abstract

Monogononta is the most speciose class of rotifers, with more than 2,000 species. The monogonont genus Brachionus is widely distributed at a global scale, and a few of its species are commonly used as ecological and evolutionary models to address questions related to aquatic ecology, cryptic speciation, evolutionary ecology, the evolution of sex and ecotoxicology. With the importance of Brachionus species in many areas of research, it is remarkable that the genome has not been characterized. This study aims to address this lacuna by presenting, for the first time, the whole-genome assembly of the freshwater species Brachionus calyciflorus. The total length of the assembled genome was 129.6 Mb, with 1,041 scaffolds. The N50 value was 786.6 kb, and the GC content was 24%. A total of 16,114 genes were annotated with repeat sequences, accounting for 21% of the assembled genome. This assembled genome may form a basis for future studies addressing key questions on the evolution of monogonont rotifers. It will also provide the necessary molecular resources to mechanistically investigate ecophysiological and ecotoxicological responses.

The complete mitochondrial genome was obtained from the assembled genome data sequenced by next generation sequencing (NGS) technology from the monogonont rotifer Brachionus koreanus. The mitochondrial genome of B. koreanus was composed of two circular chromosomes designated as mtDNA-I (10,421 bp) and mtDNA-II (11,923 bp). The gene contents of B. koreanus were identical with previously reported B. plicatilis mitochondrial genomes. However, gene orders of B. koreanus showed one rearrangement between the two species. Of 12 protein-coding genes (PCGs), 3 genes (ATP6, ND1, and ND3) had an incomplete stop codon. The A + T base composition of B. koreanus mitochondrial genome was high (68.81%). They also showed anti-G bias (12.03% and 10.97%) on the second and third position of PCGs as well as slight anti-C bias (15.96% and 14.31%) on the first and third position of PCGs.