The presence of ostreid herpesvirus 1 (OsHV-1) and the percentage of viral DNA detected in Pacific oyster Crassostrea gigas adults were investigated monthly between May and November 2012 at three locations along the southern coast of Korea. Among 210 oysters examined by polymerase chain reaction (PCR) analysis, OsHV-1 DNA was detected in only one oyster collected in August. The low detection rate of OsHV-1 DNA was consistent with the lack of reported OsHV-1-associated disease in C. gigas cultured in Korea. The sequence of the present PCR product amplified with the C2/C6 primer pair was identical to that of OsHV-1 μVar except for one nucleotide, and the sequence amplified with Del36-37F2/Del36-37R showed a 605-bp deletion as in OsHV-1 μVar. Although these sequence data are insufficient to determine genotype, the results suggest that the herpesvirus detected was similar to OsHV-1 μVar. This is the first report on the presence of OsHV-1 in adult Pacific oysters cultured in Korea.
Background The study evaluated the effects of a butaphosphan and cyanocobalamin mixture on the immune system and stress in olive flounders, Paralichthys olivaceus. Methods The mixture was intramuscularly injected into olive flounders at the current recommended dose. Furthermore, to determine the toxicity of overdose, a histological examination was performed after injection of 1-, 2-, and 4-fold higher than the recommended dose. Results Immunity parameters were altered during the first 2 weeks after a single intramuscular injection of the mixture in olive flounders (average weight 20.5 ± 1.1 g). The levels of all tested items, except glutathione and anti-protease, were higher in the treated group than in the control group in the first week; the levels of all tested items were even higher in the second week in the treated group than in the control group. The level of nitro-blue tetrazolium, myeloperoxidase, and superoxide dismutase between the two groups differed significantly. Changes in the stress response to different seawater temperatures (increase or decrease in seawater temperature by 3–5 °C using 50 L heated or cooled seawater tanks) were studied by determining the changes in cortisol and glucose levels on days 1 and 7. Both cortisol and glucose levels were significantly lower in the treated group than in the control group. Histological analysis did not reveal any abnormalities after intramuscular injection of the mixture at doses that were 1-, 2-, and 4-fold higher than the recommended dose. Conclusions Intramuscular injection of a butaphosphan and cyanocobalamin mixture is safe and effective in reducing stress and improving immunity in olive flounders.
Disease occurrence and dead cell ratio of Porphyra cultivated at Seocheon area were studied. Seaweed samples were collected monthly at 12 cultivating sites of Porphyra from Nov. 2008 to Mar. 2009. Although disease occurrence was low at the beginning of cultivation at the most of collecting sites, the occurrence increased with time. The most common symptom of Porphyra disease in this area was diatom attachment, followed by white rot disease. Licmophora sp. was the most common species of diatom and its attachment was the highest on November, the beginning of cultivation. Although the occurrence ratios of green spot disease and white rot disease were high on November, chytrid disease was increased at the end of cultivation period. Dead cell ratio of Porphyra thalli was different at each study site and cultivating time, but normally the ratio was high at the end of cultivating season. The changes of dead cell ratio could be related to the nutrition supplement and currents, and the more precise reason of dead cell ratio would be revealed by further research related to cultivating environment conditions.
Geographic distributions of pathogens are affected by dynamic processes involving host susceptibility, availability and abundance. An oomycete, Pythium porphyrae, is the causative agent of red rot disease, which plagues Pyropia farms in Korea and Japan almost every year and causes serious economic damage. We isolated an oomycete pathogen infecting Pyropia plicata from a natural population in Wellington, New Zealand. The pathogen was identified as Pythium porphyrae using cytochrome oxidase subunit 1 and internal transcribed spacer of the rDNA cistron molecular markers. Susceptibility test showed that this Pythium from New Zealand was able to infect several different species and genera of Bangiales including Pyropia but is not able to infect their sporophytic (conchocelis) phases. The sequences of the isolated New Zealand strain were also identical to Pythium chondricola from Korea and the type strain from the Netherlands. Genetic species delimitation analyses found no support for separating P. porphyrae from P. chondricola, nor do we find morphological characters to distinguish them. We propose that Pythium chondricola be placed in synonymy with P. porphyrae. It appears that the pathogen of Pyropia, both in aquaculture in the northern hemisphere and in natural populations in the southern hemisphere is one species.Key Words: Bangia; Bangiales; DNA barcoding; host specificity; Porphyra; Pythium chondricola; Rhodophyta; species delimitation; synonymization; taxonomy INTRODUCTIONAquaculture of marine algae is an important industry, especially in Asia. The production of seaweeds more than doubled between 2000 and 2012 (Food and Agriculture Organization of the United Nations 2014). The red alga Pyropia is the most consumed alga in the world, both for food and in the biomedical industry (e.g., porphyran, pycobilliproteins) (Gachon et al. 2010). In 2013, Pyropia made up about 1.8 million tons which is about 8% of the total global seaweed production, with values of US $1.2 billion (FAO FishStat et al. 2016).Pyropia cultivation losses amount to over US $10 million annually from different diseases (Gachon et al. 2010, Blouin et al. 2011, Kim et al. 2014. Diseases like greenspot disease and Olpidiopsis blight as well as red-rot disease, result in a great decrease in productivity, yield and crop value (Kawamura et al. 2005, Klochkova et al. 2012, 2016b, Kim et al. 2014. With increasing farming intensity and increasing temperatures, caused by global warming, disease severity and occurrence is also expected to increase (Ding and Ma 2005, Gachon et al. 2010).Received January 17, 2017, Accepted February 25, 2017 *Corresponding Author E-mail: joe.zuccarello@vuw.ac.nz Tel: This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 30 well investigated in aquacultural settings (e.g., Park ...
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