Analysis of Polymeric Immunoglobulin Receptor Expression in Olive Flounder (Paralichthys olivaceus) against Viral Hemorrhagic Septicemia Virus.

Polymeric immunoglobulin receptor (pIgR) mediates the transfer of polymeric immunoglobulin to protect organisms and is one of the most important mucosal effectors. In this study, the developmental stage- and tissue-specific expression of pIgR were observed before virus inoculation in olive flounder. pIgR was gradually expressed until the formation of immune tissue, exhibiting high expression in the late juvenile period; thereafter, pIgR expression gradually decreased and exhibited high expression in the spleen and skin. Moreover, pIgR expression after viral hemorrhagic septicemia virus infection was high in the kidney and spleen tissues at high density and low at low density. The results of this study can provide a basis for future studies on breeding density, virus expression, and immune system studies in fish.

The complete mitochondrial genome sequence and phylogenetic analysis for Inimicus japonicus (Scorpaeniformes: Synanceiidae).

The complete mitochondrial genome (mitogenome) of the Inimicus japonicus was analyzed by next-generation sequencing in this study. The mitogenome is 16,978 base pairs (bp) long and codes for 22 transfer RNA (tRNA) genes, 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNA), and 1 non-coding control region. The overall nucleotide composition of the mitogenome is: 29.61% for A, 29.16% for T, 25.26% for C, and 15.97% for G. Twenty-two tRNAs range from 67 to 74 bp in length, and 2 rRNA (12S and 16S) were 953 and 1,687 bp long, respectively. Phylogenetic analysis by neighbor-joining (NJ) method indicated that I. japonicus showed considerable genetic similarity (82%), and had a closer relationship in the phylogenetic tree to Synanceia verrucosa.

Morphological Development of Embryo, Larvae and Juvenile in Yellowtail Kingfish, Seriola lalandi.

This study monitored the morphological development of embryo, larvae and juvenile yellowtail kingfish, Seriola lalandi, for their aquaculture. The fertilized eggs obtained by natural spawning were spherical shape and buoyant. Fertilized eggs were transparent and had one oil globule in the yolk, with an egg diameter of 1.35 ± 0.04 mm and an oil globule diameter of 0.32 ± 0.02 mm. The fertilized eggs hatched 67-75 h after fertilization in water at 20 ± 0.5°C. The total length (TL) of the hatched larvae was 3.62 ± 0.16 mm. During hatching, the larvae, with their mouth and anus not yet opened. The yolk was completely absorbed 3 days after hatching (DAH), while the TL of post-larvae was 4.72 ± 0.07 mm. At 40 DAH, the juveniles had grown to 30.44 ± 4.07 mm in TL, body depth increased, the body color changed to a black, yellow, and light gray-blue color, and 3-4 vertical stripes appeared. At 45 DAH, the juveniles were 38.67 ± 5.65 mm in TL and 10.10 ± 0.94 mm in body depth. The fish were green with a light orange color, with 7 faint green-brown stripes on the sides of their body. At 87 DAH, the juveniles had grown to 236.11 mm in TL, 217.68 mm in fork length, and 136.5 g in weight. The fish resembled their adult form, with a light yellow-green body color, loss of the pattern on the sides of their body, and a yellow coloration at the tip of the caudal fin.

Management of Sexual Maturation and Natural Spawning of Captive- Reared Yellowtail Kingfish, Seriola lalandi, in an Indoor Rearing Tank.

This study describes results on sexual maturation and characteristics of natural spawned eggs to develop a method for the production of stable, healthy fertilized eggs from captive-reared yellowtail kingfish, Seriola lalandi. A total of 59 yellowtail kingfish were captured off the coast of Jeju Island, after which the broodstock was cultured in indoor culture tank (100 m(3)) until they were 6.1-14.9 kg in body weight. As part of the rearing management for induced sex maturation, the intensity of illumination was maintained at 130 lux. The photoperiod (light/dark; L/D) was set to a 12 L/12 D from October 2013 to January 2014, and 15 L/9 D from February 2014 to June 2014. Feeds comprised mainly EP (Extruded Pellets), with squid cuttlefish added for improvement of egg quality, and was given from April to June 2014. The first spawning of yellowtail kingfish occurred in May 3, 2014, at a water temperature of 17.0°C. Spawning continued until June 12, 2014, with the water temperature set at 20.5°C. Time of spawning was 26 times at this period. The total number of eggs that spawned during the spawning period was 4,449×10(3). The buoyant rate of spawning eggs and fertilization rate of buoyant eggs during the spawned period were 76.1% and 100%, respectively. The diameters of the egg and oil globule were 1.388 ± 0.041 mm and 0.378 ± 0.029 mm, respectively, which was higher in early eggs than in those from late during the spawned period.

Effect of salinity changes on olfactory memory-related genes and hormones in adult chum salmon Oncorhynchus keta.

Studies of memory formation have recently concentrated on the possible role of N-methyl-d-aspartate receptors (NRs). We examined changes in the expression of three NRs (NR1, NR2B, and NR2C), olfactory receptor (OR), and adrenocorticotropic hormone (ACTH) in chum salmon Oncorhynchus keta using quantitative polymerase chain reaction (QPCR) during salinity change (seawater→50% seawater→freshwater). NRs were significantly detected in the diencephalon and telencephalon and OR was significantly detected in the olfactory epithelium. The expression of NRs, OR, and ACTH increased after the transition to freshwater. We also determined that treatment with MK-801, an antagonist of NRs, decreased NRs in telencephalon cells. In addition, a reduction in salinity was associated with increased levels of dopamine, ACTH, and cortisol (in vivo). Reductions in salinity evidently caused NRs and OR to increase the expression of cortisol and dopamine. We concluded that memory capacity and olfactory imprinting of salmon is related to the salinity of the environment during the migration to spawning sites. Furthermore, salinity affects the memory/imprinting and olfactory abilities, and cortisol and dopamine is also related with olfactory-related memories during migration.