No abstract

Anisakis pegreffii is known as one of the causes of a fish-borne zoonosis, anisakidosis. Despite its significant public health and food hygiene impacts, little is known of the pathogenesis, genetic background of this parasite, at least partly due to the lack of genome and transcriptome information. In this study, RNA-seq and de novo assembly were conducted to obtain transcriptome profiles of the A. pegreffii third and fourth larvae. The third stage larvae (APL3) were collected from chub mackerel and the fourth stage larvae (APL4) were obtained by in vitro culture. In total, 47,243 and 43,660 unigenes were expressed in APL3 and APL4 transcriptomes. Of them, 18,753 were known and 28,490 were novel for APL3, while 18,996 were known and 24,664 were novel for APL4. The most abundantly expressed genes in APL3 were mitochondrial enzymes (COI, COII, COIII) and polyubiquitins (UBB, UBIQP_XENLA). Collagen-related genes (col-145, col-34, col-138, Bm1_54705, col-40) were the most abundantly expressed in APL4. Mitochondrial enzyme genes (COIII, COI) were also highly expressed in APL4. Among the transcripts, 614 were up-regulated in APL3, while 1,309 were up-regulated in APL4. Several protease and protein biosynthesis-related genes were highly expressed in APL3, all of which are thought to be crucial for invading host tissues. Collagen synthesis-related genes were highly expressed in APL4, reflecting active biosynthesis of collagens occurs during moulting process of APL4. Of these differentially expressed genes, several genes (SI, nas-13, EF-TSMT, SFXN2, dhs-27) were validated to highly transcribed in APL3, while other genes (col-40, F09E10.7, pept-1, col-34, VIT) in APL4. The biological roles of these genes in vivo will be deciphered when the reference genome sequences are available, together with in vitro experiments.

The complete mitochondrial genome sequence of Microcotyle caudata was determined. The entire circular mitochondrial genome is 14,267 bp in length, comprising 12 protein-coding genes (PCGs, lacking atp8), 22 tRNA, 2 rRNA, several non-coding region, and one repeat sequence. The total length of the M. caudata mitochondrial genome was 140 bp shorter than a congeneric species, M. sebastis, but the arrangement of all 36 genes was identical with each other. The phylogenetic analysis of the concatenated 12 PCGs also revealed that M. caudata was most closely clustered with M. sebastis.

No abstract

We developed a PCR assay targeting the 28S rDNA of Kudoa iwatai (Multivalvulida: Myxozoa) and investigated the prevalence of infection in rock bream Oplegnathus fasciatus, which is commercially an important aquaculture species in Korea, with this assay. Detection limit of the PCR assay was 2.5 fg/μl with plasmid DNA and 8.6 × 10 spores/ml with purified spores, respectively. This PCR assay did not amplify DNA of other Kudoa species (Kudoa septempunctata, Kudoa lateolabracis, Kudoa thyrsites) tested. Sliced muscles of whole body from 318 rock bream (wild and cultured) were examined by this PCR assay and also with the naked eyes. All of the wild fish did not produce amplicons nor did harbor visible Kudoa cysts (0/70). Three of the cultured fish were PCR-positive and also harbored visible Kudoa cysts (3/248, 1.2%). The sequences of amplicons (574 bp) were 100% identical with those of the K. iwatai already registered in Genbank. When the visceral organs of these three fish were examined, visible cysts were not found, but one stomach sample was found to be PCR-positive. There was no difference in the prevalence of infection estimated by PCR assay and the presence of visible Kudoa cysts in our samples. This is thought to be because the development of K. iwatai is already completed and only mature Kudoa cysts existed in our samples.