First report of Perkinsus olseni infections in blood cockles Tegillarca granosa on the south coast of Korea.

The protozoan parasite Perkinsus olseni has become a focus of attention since it has been responsible for mass mortalities and economic losses in a wide range of bivalve hosts globally. The P. olseni host range along the south coast of Korea may extend beyond what was previously understood, and blood cockles in the Family Arcidae are also suggested to be potential hosts of P. olseni. In the present study, we applied histology and molecular techniques to identify Perkinsus sp. infections in the blood cockles Tegillarca granosa, which have been commercially exploited on the south coast of Korea for several decades. Histology and molecular techniques, including genus-specific immunofluorescence assay, species-specific fluorescence in situ hybridization, and phylogeny based on the ribosomal DNA internal transcribed spacer region revealed that T. granosa is infected by P. olseni, although the prevalence was low (0.5%). Histology revealed massive hemocyte infiltrations in the mantle, gill, and digestive gland connective tissues, indicating that the infection exerts negative impacts on the host cockles.

First Report of Enterocytozoon hepatopenaei Infection in Giant Freshwater Prawn (Macrobrachium rosenbergii de Man) Cultured in the Republic of Korea.

In the Republic of Korea, Enterocytozoon hepatopenaei (EHP) was first isolated from Pacific whiteleg shrimp in April 2020; however, there are no existing reports of EHP infection in other shrimp or prawns. Here, we aimed to investigate EHP infection and its prevalence in giant freshwater prawn farms in the Republic of Korea. We tested prawns from 22 farms for EHP infection, and samples from eight farms showed positive EHP infection results in 2021. In EHP-infected prawn farms, the prevalence ranged from 4.9% to 18.2%. The prevalence of EHP infection in the Republic of Korea, derived from the prevalence in prawn farms, was estimated to be 0.8% in 2021. The proliferation of EHP was observed within the hepatopancreatic epithelial cells of prawns using H&E and Giemsa staining. Mature EHP was observed in the sinus between epithelial cells of the digestive tubules. Phylogenetic analysis revealed a clade distinct from the previously reported EHP in Pacific whiteleg shrimps. This is the first report of EHP infection in a giant freshwater prawn in the Republic of Korea, where the prevalence of EHP infection is not high, but it is recognized as an emerging disease that requires periodic monitoring and quarantine management in giant freshwater prawns.

Complete mitochondrial genome of the abalone shell-boring Polydora hoplura (Polychaeta, Spionidae).

Polydora hoplura Claparede 1868 (Polychaeta, Spionidae) is a mollusk shell-boring species which has been reported as a harmful species. In the present study, we sequenced and reported the mitochondrial genome (mitogenome) of P. hoplura from Korea. Its mitogenome was determined by long range PCR and primer walking. The mitogenome was found to be 17,707 bp in length and contained two ribosomal RNAs (rRNAs), 23 transfer RNAs (tRNAs), and 12 protein-coding genes which showed different gene arrangement with that in related mitogenomes of species of Sedentaria (Annelida). Interestingly, the atp8 gene was not found in the mitogenome of P. hoplura, whereas it is present in the mitogenomes of related species P. brevipalpa and P. websteri. Moreover, nad2 (3' end) and cox1 (5' end) genes overlapped in 23 bases. The mitogenome structure and gene contents of P. hoplura provide useful information on the evolution and phylogenetic relationship among polychaete species.

Rapid Detection of Red Rot Disease Pathogens (Pythium chondricola and P. porphyrae) in Pyropia yezoensis (Rhodophyta) with PCR-RFLP.

Red rot disease is one of the best-known algal diseases infecting red algae Pyropia species. This disease decreases the quality and quantity of Pyropia aquaculture products in Korea, Japan, and China. Recently we found that Pythium chondricola (Oomycetes) infects blades of Pyropia yezoensis. Therefore, two Pythium species (P. chondricola and P. porphyrae) have been reported as red rot disease pathogens. In this study, we developed a species-specific molecular marker for distinguishing between the two red rot disease pathogens. Using a polymerase chain reaction restriction fragment length polymorphism method based on the mitochondrial cytochrome c oxidase subunit 2 (cox2) and nuclear ribosomal RNA large subunit regions, we classified these two Pythium species without a sequencing step. This new method had high specificity and efficiency for detecting red rot disease pathogens at the species level for both of the cultured and field samples. Therefore, the molecular markers developed in this study are effective for long-term monitoring of the infection and distribution pattern of each Pythium species in Pyropia aquaculture farms. Moreover, molecular monitoring can provide useful information for predicting infection and preventing mass mortality of Pyropia species by red rot disease.

First report of Labyrinthula zosterae (Labyrinthulomycetes) as the causal pathogen of wasting disease in the seagrass Zostera marina in Korea.

Zostera marina L. plants have been seriously impacted by wasting disease along the Atlantic coasts of North America and Europe since the 1930s (Muehlstein 1989). Sudden declines in the population sizes of Zostera marina affect primary and secondary producers of different trophic levels in blue carbon ecosystems (Gleason et al. 2013). Muehlstein et al. (1991) first identified Labyrinthula zosterae (Labyrinthulomycetes) as the pathogen causing wasting disease in Zostera marina. However, there have been no reports of wasting disease pathogens affecting seagrass in Korea. In this study, we collected leaves of Z. marina showing symptoms of wasting disease in the southern region of South Korea (Dongdaeman, Namhae, Gyeongnam Province) during field monitoring (from April to September 2013). The pathogens of wasting disease, Labyrinthula zosterae has been isolated from the infected leaves of Z. marina and established as a culture strain (Supplementary Figure 1). Samples of Z. marina and L. zosterae were deposited at the Fisheries Seed and Breeding Research Institute (previous Seaweed Research Center, National Institute of Fisheries Science, South Korea). Microscopic examination of the infected leaf tissues revealed fusiform or spindle-shaped vegetative Labyrinthula cells (4-5 × 15-20 µm). These were similar in size and shape to those previously described for Labyrinthula species. The fusiform cells were cultured in 1% serum seawater agar medium, and they formed colonies and showed gliding motility along a network of hyaline slime filaments. To validate the pathogenicity, re-inoculation tests by L. zosterae were performed with the isolated strains in accordance with Koch's postulates. Healthy leaves of Z. marina collected from the field were used in the re-inoculation tests and were cultured at 15°C under white fluorescent irradiation of approximately 20 µmol·photons·m-2·s-1 and a 12:12-h light:dark cycle (Supplementary Figure 1). Labyrinthula zosterae re-isolated from artificially infected leaves of Z. marina was confirmed by DNA sequence similarity analysis. Total genomic DNA from the infected leaf cells and the culture strains was extracted using the QIAamp DNA Stool Mini Kit (Qiagen, Germany). Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA were determined to identify Labyrinthula species. L. zosterae-specific primers (Lz2forward (5'- CTAAGACTAAACGAGGCGAAAGCCTAC-3') and Lz2reverse (5'-AGGTTTACAAAACACACTCGTCCACA-3') in Bergmann et al. (2011)) were used to confirm the infection of L. zosterae in the leaves from the field samples and the re-inoculation test samples. Next, PCR products were cloned using a pLUG-Prime® TA-cloning Vector (iNtRON Biotechnology, Korea) and commercially sequenced (SolGent, Korea). The ITS sequence of Korean L. zosterae (accession number MW357748) showed high sequence similarity (99.3-100%) with that of L. zosterae deposited in GenBank (National Center for Biotechnology Information) from BLAST searches. These findings confirm that this is the first report of L. zosterae as the causal pathogen of wasting disease in Z. marina in Korea.

Effects of RNA interference-mediated knock-down of hypoxia-inducible factor-α on respiratory burst activity of the Pacific oyster Crassostrea gigas hemocytes.

In mammals, hypoxia-inducible factor-1 α (HIF-1α) is known to play important roles not only in oxygen homeostasis but also in innate immune responses. In this study, to assess the functional role of HIF-α in respiratory burst activity of Crassostrea gigas hemocytes, oysters were injected with HIF-α- or green fluorescent protein (GFP)-targeted-long double-stranded RNAs (dsRNAs), and at 1, 3, and 7 days post-injection, knock-down of C. gigas HIF-α expression and production of reactive oxygen species (ROS) were analyzed. Expression of HIF-α in mantle, gill, and hemocytes of C. gigas was clearly down-regulated by injection of the HIF-α-targeted-long dsRNA, but was not inhibited by the GFP-targeted-long dsRNA, indicating that HIF-α expression was suppressed through sequence-specific and systemic RNA interference (RNAi). Respiratory burst activity of hemocytes was significantly increased by administration of GFP-targeted-long dsRNA. However, knock-down of HIF-α expression led to significant decrease of chemiluminescence (CL) response of C. gigas hemocytes at 3 and 7 days post-administration of HIF-α-targeted-long dsRNA, indicating the critical role of HIF-α in activation of respiratory burst activity of oyster hemocytes.

Personality characteristics of mothers of children with attention deficit hyperactivity disorder as assessed by the Minnesota multiphasic personality inventory.

OBJECTIVE: The current study investigated the personality characteristics of mothers of children with attention deficit hyperactivity disorder (ADHD) using the Minnesota Multiphasic Personality Inventory (MMPI). METHODS: Fifty mothers (average age of 38.1+/-4.2 years) of children with ADHD not having comorbidity (37 boys, 13 girls; average age of 8.5+/-1.9 years) and 59 mothers (average age of 38.1+/-2.7 years) of comparison children (37 boys, 13 girls; average age of 8.1+/-1.5 years) completed the Korean version of the MMPI. Only mothers whose psychiatric health was verified by the Structured Clinical Interview for axis-I DSM-IV disorders (SCID-IV) were included in current study. RESULTS: After controlling for maternal age, maternal education level, children's gender, age, and total and verbal intelligence quotient (IQ), the MMPI scores of the mothers of children with ADHD were significantly higher on the depression (D), hysteria (Hy) and psychasthenia (Pt) scales than those of the mothers of children in the comparison group. CONCLUSION: These results suggested that even psychologically healthy mothers of children with ADHD alone might be depressed, histrionic and anxious.

Growth and reproductive patterns of Undaria pinnatifida sporophytes in a cultivation farm in Busan, Korea.

Monthly growth and reproduction of Undaria pinnatifida sporophytes were examined over a period of 5 months in a cultivation farm in Korea. A total of 11 characters of Undaria were measured to determine a reliable morphological character representing its growth and reproduction. Plant weight of Undaria sporophytes increased steadily over the experimental period, but it increased in four different ways. Undaria pinnatifida increased body weight by growth in length and width (October-early December), and by growth in width with the thickening of blade and stipe when sporophytes began to be fertile (December-January). In the middle of January, growth in length and width had almost stopped with the maturation of Undaria sporophytes. Finally, the weight of Undaria increased again by growth in width at the end of February. Present results indicate that Undaria sporophytes increase body weight by growth in length and width at different times, and the relationship between reproduction and vegetative growth is exclusive. Plant weight was positively correlated and fitted well with stipe width and blade width. The blade of Undaria was very thin (ca. 254 mum) and breakable by wave action, but its stipe was strong and relatively thick (ca. 8.7 mm). Furthermore, the fertility of U. pinnatifida was fitted better with stipe width than blade width. Thus, we suggest that the stipe width is the most feasible character with which to estimate the growth and reproduction of U. pinnatifida sporophytes in the cultivation farm.