• The Korean Journal of Malacology
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• v.32 no.1
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• pp.1-7
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• 2016

The developmental stage of germ cells during oogenesis can be categorized into six stages with histological features: (1) oogonium, (2) previtellogenic oocyte, (3) initial vitellogenic oocyte, (4) early active vitellogenic oocyte, (5) late active vitellogenic oocyte and (6) ripe oocyte. The size of oocyte, nucleus and nucleolus illustrated the increase tendency but size ratio of nucleolus to nucleus was decreased during oogenesis. During oogenesis the stainability in the cytoplasm of oocyte changes from basophilic to eosinophilic in H-E stain. And egg stalk and outer jelly membrane was developed in the oocyte. These histological changes are seemed to be yolk accumulation in the oocyte and preparation process for spawning.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.61-68
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• 1976

For the artificial precocious breeding of abalone effects of changes in environmental parameters, water temperature and light period, on the induction of spawning have been studied. Subtidal specimens of Haliotis discus hannai were collected irregularly for 6 times from April to June 1975 in Chungmu Bay near Jukdo Island, the southern coast of Korea. One hundred and fifty specimens were reared in 4 aquarium tanks in the laboratory and in a creel submerged in the sea during the period of 60 days from April 24 to June 23, 1975. The all groups kept in the four tanks and a creel showed very high spawning rates $(70\~100\%)$, compared to those inhabited the natural environment at sea until right before the spawning time $(0\~50\%,\;average\;16.4\%)$. From the results of the present induced spawning, the parameters can be discussed as follows: It seems likely that photoenvironment may stimulate to produce and secrete some internal substances which may concern to giving the fertilizing ability to the eggs before spawning and to inducing spawning, but the temperature may not be a factor for this concern. For effective precocious breeding, it seems to require that abalones are to be realoed under controlled conditions of darkness below 2,000 lux even during day time for more than 60 days before inducing spawning.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.452-457
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• 2008

This study analyzed the proximate compositions, total amino acids, and fatty acid compositions in muscle and viscera of 51-month-old triploid and diploid Pacific abalone, Haliotis discus hannai. Proximate composition analysis showed that the muscle of diploid abalones had a higher protein and ash ratio than that of triploid abalones, while there was no significant difference in the ratios of moisture and fat (P>0.05). The triploid abalones had a significantly higher ratio of carbohydrate in muscle than the diploid abalones (P<0.05), which suggests that the transference of carbohydrates from muscle to gonad is decreased in sterile triploid organisms. Amino-acid analysis indicated that the total content was 133.42 mg/g in diploid muscle and 151.46 mg/g in triploid muscle. Taurine, arginine, glutamine, glycine, glutamic acid, alanine, and leucine, which are the major amino acids in abalone, were measured as 84.64 mg/g in triploid muscle and as 73.92 mg/g in diploid muscle. The essential amino acid content of triploid muscle (38.83 mg/g) was significantly higher than that of diploid muscle (31.94 mg/g) (P<0.05). Saturated fatty acids and monoene fatty acids were abundant in triploid muscle and polyene fatty acids were abundant in diploid muscle. Therefore, triploid Pacific abalone appears to be a good nutritional food source.

• Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.249-253
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• 2014

An 8-week feeding experiment was conducted to determine the influence of dietary distillers dried grain (DDG) on the growth and body composition of juvenile abalone Haliotis discus hannai. Five diets were formulated to contain 0% (DDG0), 15% (DDG15), 30% (DDG30), 45% (DDG45), and 60% (DDG60) DDG, and three replicate groups of abalone (average body weight: $3.6{\pm}0.21$ g) were fed one of the experimental diets at a feeding rate of 5% body weight per day once daily (17:00 h) for 8 weeks. Survival, shell length, and shell width of juvenile abalone were not affected by dietary DDG levels (P > 0.05). Weight gains of juvenile abalone fed DDG15 and DDG30 diets were not different compared to DDG0, but abalone fed DDG45 and DDG60 diets gained less weight than those fed DDG0 (P < 0.05). Soft body weight/body weight ratio of juvenile abalone fed the DDG60 diet was lower than that of those fed the DDG0 diet (P < 0.05), but proximate composition of the soft body was not affected by dietary DDG levels (P > 0.05). The results of this experiment suggest that DDG is a good replacement for wheat flour and soybean meal, and can be used up to 30% in the diet to maintain the growth performance of the juvenile abalone.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.13-17
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• 2015

Oxytetracycline (OTC) has been widely used in aquaculture field as a therapeutic and prophylactic agent because of its broad-spectrum activity against gram-positive and negative bacteria. Residual oxytetracycline (OTC) was studied after spray treatment of cultured abalone, Haliotis discus hannai. Muscle concentration of OTC was determined after spray treatment ( 4,000, 7,000, 10,000 ppm) in the abalone. Muscle samples were taken at 0, 1, 3, 7, 14, 21 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330 and 360 day post-dose. OTC analyses were carried out by high performance liquid chromatography (HPLC). In 4000, 7000 and 1000 ppm treatment for small size abalones, OTC levels at 1 day post-dose, have been dramatically decreased by 8.34, 3.35 and 4.47 ug/g, respectively. For medium size abalones, concentration were measured as 7.58, 15.62 and 7.8 ug/g, respectively. Those of large size abalones also were observed as 11.31, 12.38 and 15.28 ug/g, respectively, at 1 day post-dose. No significant differences in residual OTC depletion in muscles were observed between the size of abalones. More than 0.2 mg/kg of OTC was detected in muscle tissues and the residues were found over 60 days after treatment. It is expected that these results would contribute to improve recommended withdrawl periods of OTC for a safer seafood supply.

• Journal of Aquaculture
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• v.8 no.3
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• pp.159-170
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• 1995

Triploid abalone, Haliotis discus hannai, was induced by the cold $(0^{\circ}C\;and\;3^{\circ}C)$ or the heat $(35^{\circ}C\;and\;40^{\circ}C)$ shock procedure with fertilized eggs, 12 min. or 32 min. post fertilization with the various time intervals of shock duration. Fertilization rate of each experimental group was not significantly different from that of corresponding diploid control (P>0.05). However hatching rates and normality rates of triploid larvae were significantly different from those of corresponding diploid control (P <0.05). In heat shock groups at $40^{\circ}C$, fertilization rate of eggs was extremely low $(0\~2.7\%)$ and hatched larvae were not detected in these treatment groups. Incidence of triploidy was confirmed by chromosome count and the highest rates of triploid $(84.0\%)$ revealed in cold $(3^{\circ}C)$ shock with 15 min. treatment duration 12 min. after fertilization. The number of diploid chromosome was 2n: 36, and that of tiploid was 3n=54.

• Journal of Aquaculture
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• v.7 no.1
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• pp.9-20
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• 1994

To find out suitable indoor rearing tank shape and stocking density of the abalone Haliotis discus hannai, young abalones were reared in the square or ellipse shape tanks with various stocking densities and were fed dried sea mustard, Undaria Pinnatifida HARVEY for three years. There were no significant differences between the square rearing tank and the ellipse one in growth rate and survival rate. With regard to vertical design of rearing tanks with three floors, the significant differences were not found among culture floors. However, the growth and survival rates of young abalones from the running water system were significantly higher than those of the abalones from the circulating system (P< 0.05). For the stocking density experiment with 1,000, 1,500 and 2,000 individuals of 20 mm young abalone, there was no significant differences in growth and survival rates among these groups. However, in that of 200-400 individuals of 40 mm abalone and 100-300 individuals of 50 mm abalone, the lower stocking density of young abalone showed the higher growth and survival rates. The lower stocking density and the smaller size of young abalones showed the higher daily feeding rate and feed efficiency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.544-550
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• 2020

This study was conducted to estimate the genetic improvements by selection criteria using the genetic parameters and breeding values for population of abalone Haliotis discus hannai. Genetic parameters and breeding values were estimated using all measurement data of growth traits (shell length, shell width and total weight) at 18 and 30 months old after artificial fertilization for 3,029 individuals produced in April 2014. Growth traits all exhibited moderate heritability (0.253-0.354). So it is considered that family selection will be more advantageous than individual selection. It was found that a higher genetic improvement could be expected when selecting the top 10% based on the breeding values of total weight rather than other traits. In particular, a higher genetic improvement could be expected when selecting the top 10% at 30 months old than 18 months old after artificial fertilization. This seems to be because the selection differential and heritability were higher at the 30 months old. Therefore, by estimating genetic parameters and breeding values of a population for production of the next generations by stage of growth, if they are used properly in selection and mating according to the improvement direction, it is considered that more breeding effects can be expected.

• Fisheries and Aquatic Sciences
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• v.10 no.3
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• pp.119-126
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• 2007

The analysis of expressed sequence tags (ESTs) is an efficient approach for gene discovery, expression profiling, and the development of resources for functional genomics. To analyze the transcriptome of the abalone Haliotis discus hannai, we conducted EST analysis using seven cDNA libraries made from gill, gut, hepatopancreas, skin, muscle, testis, and ovary. Redundant ESTs were assembled into overlapping contiguous sequences using the assembly program ICAtools. We found that the total 1,393 ESTs formed 135 clusters and 951 singletons, indicating that the overall redundancy of the library was 22%. Of the 1,393 clones, BLAST identified 1,278 clones (91.7%) as known genes; 115 clones (8.3%) did not match any previously described gene. Based on the major functions of their encoded proteins, the identified clones were classified into 16 broad categories. Sequence analysis revealed the presence of micro satellite-containing genes that may be valuable for further gene mapping studies. This study contributes to the identification of numerous EST clones that can be applied to further clarifying the genetics and developmental biology of abalone.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.4
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• pp.280-291
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• 2019

Potential utility of 14 candidate housekeeping genes as normalization reference for RT-qPCR analysis with developmental samples (fertilized eggs to late veliger larvae) in Pacific abalone Haliotis discus hannai was evaluated using four different statistical algorithms (geNorm, NormFinder, BestKeeper and comparative ΔCT method). Different algorithms identified different genes as the best candidates, and geometric mean-based final ranking from the most to the least stable expression was as follow: RPL5, RPL4, RPS18, RPL8, RPL7, UBE2, RPL7A, GAPDH, RPL36, PPIB, EF1A, ACTB and B-TU. The findings were further validated via relative quantification of metallothionein (MT) transcripts using the stable and unstable reference genes, and expression levels of MT were greatly influenced according to the choice of reference genes. In overall, our data suggest that RPL5 and RPS18, either singly or in combination, are appropriate for normalizing gene expression in developmental samples of this abalone species, whereas ACTB, B-TU and EF1A are less stable and not recommended. In addition, our findings propose that standard deviations in geometric ranking as well as geometric mean itself should also be taken into account for the final selection of reference gene(s). This study could be a useful basis to facilitate the generation of accurate and reliable RT-qPCR data with developmental samples in this abalone species.