• Korean Journal of Poultry Science
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• v.48 no.2
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• pp.69-80
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• 2021

We conducted a 4 × 4 diallel cross-mating test using 934 chickens from four grandparent stock lines to develop a new synthetic breed of Korean native chicken. The mean values, combining ability, and reciprocal effects on survival rate, body weight, and hen-day egg production were analyzed. In phenotypes, most chickens have yellowish-brown, reddish-brown and mixed color feathers. The average survival rate was 86.8±12.3%, with the highest in YH combination. Specific combining ability (SCA) had a greater effect on survival rate than general combining ability (GCA), and the SCA of HY combination was the highest. The 16 cross-combinations were distinctly divided into three weight groups according to their genetic characteristics. At 12 weeks of age, GCA showed a greater effect on weight than SCA, and the SCA of FH combination was the highest. The age at first egg laying was 157 days, and the crosses reached sexual maturity faster than the pure lines. The egg production rate was highest in SY at 79.5±2.1%. The GCA and SCA for hen-day egg production were similar, and the SCA was highest in the HS and FY combinations. The reciprocal effect showed that the offspring's egg production rate was high when S and Y were maternal parents in almost all combinations. In conclusion, FH and HF combinations, which have excellent growth performance, are the most desirable paternal parent stock strains, and FY, FS, HY, and SY combinations, which have excellent laying performance with moderate weight, are the preferred maternal strains.

• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.25-33
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• 2010

Effects of different salinity levels on spawning performance, embryonic development and early viability of a euryhaline medaka species, Oryzias dancena, were examined. O. dancena were able to spawn eggs in a wide range of salinity from 0 to 70$^{\circ}/_{\circ\circ}$, however, the spawning frequency was lowered in complete freshwater (0$^{\circ}/_{\circ\circ}$) and in highly salted water (70$^{\circ}/_{\circ\circ}$). Fertilization success was negatively affected when the environmental salinity was higher than the salt concentration found in normal seawater. Embryonic viability and hatching success were also inversely related with the salinity levels. Typical abnormality was observed in developing embryos incubated at high salinities (30, 45 and 60$^{\circ}/_{\circ\circ}$). In addition, the time to hatch was significantly delayed with increasing salinities: peak hatching occurred at 12~14 days post fertilization (dpf) in freshwater and at least at 17 to 18 dpf in 60$^{\circ}/_{\circ\circ}$. Mean survival rates of the hatched larvae up to 7 days post hatching (dph) were at least 97% in salinity levels ranging from 0 to 30$^{\circ}/_{\circ\circ}$. However, larvae reared in 45 and 60$^{\circ}/_{\circ\circ}$ experienced significant mortality, especially in the early phase, resulting in only 75% and 64% survival rates up to 7 dph, respectively.

• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.222-236
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• 1994

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.283-291
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• 2006

The efficiency to detect mutagenicity of the system using a specific locus mutation of Bombyx mori was examined and improved. In the system, mutagenicity could be detected by the egg colour manifested by the pe and/or re genes, which is a kind of recessive visible mutation of the insect. Among tested four mutagens, MMC had specially high sensitivity in the oocytes of silkworm and EMS had in the spermatozoa. PCB and dioxin showed a positive effect in both the oocytes and spermatozoa. In a consequence of sensitivity of mutagen by mating number of male moth of B. mori, treated mutagen, there was no difference between one mating - and three mating - male moth in sensitivity of mutagen. Sun3ho, B. mori variety, which showed high sensitivity to mutagens was improved in the major characteristics by crossing of C5 and N12.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.2
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• pp.191-196
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• 1996

Age growth and spawning period of Enedrias nebulosus were estimated based on otoliths taken from a total of 255 fish samples of E. nebulosus, which were caught in the costal waters of $Kod\v{o}kto$ near Pusan from November 1990 to October 1991. Marginal increment analysis indicates that annuli in E. nebulosus are formed in December. Spawning period was estimated to be November to January, with a peak in December. The von Bertalanffy growth equations were expressed as follows: $L_t=33.64(1-e^{-0.1357(t+2.6853)})$ and $W_t=414.11(1-e^{-0.1357(t+2.6853)})^{3.9745}$, Where $L_t$, is total length in cm, $W_t$, is total weight in g and t is age in year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.550-555
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• 1999

The growth and spawning time of juvenile Ammodytes personatus were analyzed based on the daily growth increment in otolith reading of the sample caught in the coastal waters of Shinsudo, Sacheon from March 20 to May 1, 1988. Daily growth increment in otolith was formed once a day. The estimated spawning time ranged from November, 1987 to March, 1988. The von Bertalanffy growth model and the Gompertz growth model were expressed as, $TL=87.80(1-e^{-0.0074(t+10.79)})$ and $TL=72.59 e^{-1.8417\;e-0.0152t}$ respectively, where TL is total length in mm, t is age in day.

• Korean Journal of Poultry Science
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• v.43 no.4
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• pp.273-279
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• 2016

Recently, it was reported that certain polymorphisms in the growth hormone secretagogue receptor gene (GHSR) are associated with the growth of chickens. However, the correlation between GHSR polymorphisms and economic traits has not been investigated in Korean native chickens (KNCs). Therefore, the objective of this study was to confirm the suitability of the GHSR gene as a candidate for genomic selection and identify a genetic marker for KNCs. A total of 220 KNCs from six breeds raised at the National Institute of Animal Science were genotyped for the c.739+726 SNP in the GHSR gene using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP), and the sequence for a subset of 30 birds was analyzed using direct sequencing. The association between the SNP genotypes and the economic traits of the KNCs was analyzed using the statistical package for the social science (SPSS) software program. The association analysis between the c.739+726T>C SNP and economic traits revealed that the SNP was significantly associated with body weight at 150 and 270 days (BW150 and BW270, respectively) in all KNCs (p<0.01), BW150 in KNC (Gary) (p<0.05), and egg production number in KNC (White, p<0.05). In addition, the SNPs discovered using direct sequencing (513A>G, 517A>T) had a significant effect on the body weight and egg production traits (p<0.05). In conclusion, these results might be useful as a basis for studies on the improvement of KNC breeds. Furthermore, these results suggest that the SNPs (c.739+726T>C, 513A>G, and 517A>T) located in the GHSR gene could be useful molecular genetic markers for KNCs.

• Korean Journal of Ichthyology
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• v.2 no.2
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• pp.169-181
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• 1990

The development of eggs and larvae, and minute scale-like tubercles on the skin surface of larval Acantlaorhodeus gracilis from Korea were observed. They spawned from late March through the middle of June. A fish spawned at least 5 times and the number of eggs averaged 304 per oviposition. Unfertilized eggs are nearly ovoid-shaped(mean$\pm$SD=$2.09{\pm}0.04\;mm$ in length with range of 2.05 to 2.13 mm and mean$\pm$SD=$1.26{\pm}0.02\;mm$ in breadth with range of 1.24 to 1.30 mm measured for the 50 eggs) and opaque yellow color. The tip of egg membrane at the animal pole side swelled and formed a few hilly projections. The shape of the eggs was just like a loquat. Most of embryos began to hatch out in thirty-eight hours after insemination at $22{\pm}1^{\circ}C$ in water temperature. As regards the morphological characters of the eggs and larval development, Acan. gracilis was similar to Acan. asmussi, Acheilognathus rhombeus, A. longipinnis and Pseudoperilampus typus. The larvae of this species is unique particularly in the following two characters, i.e., 1) scale-like tubercles ellipsoided in a diagonal cross section on the whole body and 2) incessant wiggly movement pattern as that of fly maggot, with the larvae of the above mentioned species. These characters seem to reflect the phylogenetic relationships among acheilognathine fishes. On the other hand, this species and Acan. asmussi are spring-summer spawning bitterlings. And also these species never retard the larval growth in such larval stage as the duration from Stage B to Stage D.

• Journal of Sericultural and Entomological Science
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• v.51 no.1
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• pp.73-77
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• 2013

Silkworm transgenesis scientists have done some genetic modification work on multivoltine silkworms, but that type of silkworms is less commercial feasible. They are easy to manipulate, because they breed all year round. But the commercial silkworm variety must undergo hydrochloric acid treatment at a high temperature to be artificially hatched. Hydrochloric acid penetrates through the holes in the silkworm eggs, fatally damaging their reproduction. So it had been thought that altering the properties of the commercial silkworm variety would be very difficult. So we have tried to make from diapause to non-diapause eggs using diapauses varieties, 'Backokjam' and 'Jam 124'. At present, our group has establishing the conditions for non-diapause eggs. Oviposited eggs after 40 ~ 60 hours were incubated for 24 hours at $15{\sim}20^{\circ}C$ with dark condition. Non-diapause eggs were completely induced. The hatching rate, molting rate and pupation rate of non-diapause 'Jam 124' and 'Backokjam' eggs showed no differences compared to diapause eggs. When transgenic silkworm using the non-diapause eggs, the hatching rate showed that non-diapause eggs induced from diapause were 40 ~ 70%, diapause eggs treated with artificial incubation were 10 ~ 30%, and polyvoltine strains, HM eggs were 30 ~ 50%. Therefore, we suggest that modification techniques of the commercial silkworm eggs adequate for silkworm transgenesis can be used to develop transgenic silkworms more easily.

• Korean Journal of Poultry Science
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• v.16 no.4
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• pp.239-252
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• 1989

The present study was carried out to investigate the improvement of major production traits with the published data of twenty-two years'random sample tests held in Korea from 1966 to 1988. Eight traits-roaring viability, laying viability, age of sexual maturity, hen day egg production, hen-housed egg production, egg weight, feed requirement, 500 days body weight-were dealt with in this study. The results obtained in this study are summerized as follows； 1. Total mean value for rearing viability was 99.4% in 1980s. Mean value for rearing viability of colored hen was 99.5% and white hen was 99.06% in 1980s. Mean value for laying viability was increased by 0.98%, 0.86% and 0.86% per year in pool data, white hen and colored hen, respectively. 2, Age of sexual maturity was decreased from 171.1 day to 160.8 day in pool data during 1960s- 1910s but increased to 162.4 day in 1980s； and decreased from 160.5 day to 1595 nay in white hen but increased from 163.7 day to 166.1 day in colored hen during 1970s-1980s. 3. Mean values for hen-day egg production were increased by 0.96%, 1.09% and 0.63% per year in pool data, colored hen and white hen, respectively. 4. Mean values for hen housed egg production were increased by 45, 5.37 and 4.23 per year in pool data, colored hen and white hen, respectively. 5. Egg weight were improved by 0.22g and 0.25g per year in pool data and colored hen but decreased by 0.03g in white hen. 6. feed requirement were improved by 0.04, 0.05 and 0.1 per year in pool data, white hen and colored hen, respectively. 7. 500 days body weights were increased by 0.38g per year in pool data but decreased by 14.95g and 10.37g in colored hen and white hen, respectively. 8. Estimate of correlation coefficient between age of sexual maturity and other factors such as hen day egg production. hen housed egg production, egg weight and 500 days body weight were -0.4512, -0.2876, -0.4376 and 0.2045 in pool data； -0.358, -0.1530 0.3475 and 0.1208 in white hen； 0.0989, 0.1181, 0.2885 and 0.2248 in colored hen, respectively. Estimates of correlation coefficient between hen day egg production and egg weight were 0.6233, -0.2259 and 0.2973 in Pool data, white hen and colored hen； between hen day egg production and 500 days body weight, 0.2417, 0.0774, -0.4787 ： between hen-housed egg production and egg weight, 0.6171, -0.2706, 0.4579： between hen housed egg production and 500 days body weight, 0.3082, -0.0792, -0.3368： between egg weight and 500 days body weight, 0.2742, 0.2205, 0.1354, respectively.