• The Korean Journal of Malacology
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• v.15 no.2
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• pp.115-119
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• 1999

We investigated the processes of egg and larval developments for aquaculture technique development of seedling production fo the flat oyster, Ostrea denselamellosa. Teo flat oyster of larviparous type was different from the pacific oyser (ovivarous type) because their larvae (trochophore and prodissoconch larvae) in the gill released into the seawater. The process of egg development was observed by artificial fertilization at $25^{\circ}C$, using a dissecting method. The sizes of Unfertilized eggs ranged from 80 to 90 $\mu\textrm{m}$ and fertilized eggs with globule-shape was 90-100 $\mu\textrm{m}$. The Polar body appeared after fertilization and egg cleavage began within 1 hour, reaching the blastula stage after 10 hours. The trochophore in the gill appeared 2-3 days after fertilization and grew to the prodissoconch larvae (130 140 $\mu\textrm{m}$) having a complete shell after 1-2 days. The shell of prodissoconch larvae grew to 205 220 $\mu\textrm{m}$ after 10 hours, and then they became umbo stage larvae showing oval in shape. The velum of umbo stage larvae was degenerated about 17-20 days after fertilization and grew into a pediveliger with a developed foot, at this time, the shell length size was 320 360 $\mu\textrm{m}$.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.861-873
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• 2017

The present study was conducted to investigate the developmental characteristics of Propylea japonica Thunberg (Coleoptera : Coccinellidae), a predator of aphids under laboratory conditions. The development times of the egg and immature stages of Propylea japonica were investigated at ten constant temperatures(15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35 and $38{\pm}1^{\circ}C$; 14L:10D; $60{\pm}5%$ RH). Development time was longest at $17.5^{\circ}C$. The developmental periods of P. japonica from the time of egg oviposited to adult emergence was 36.9 days at $17.5^{\circ}C$, and it decreased ash temperature increasing. Threshold temperature of development and degree days of the P. japonica from egg to adult were $11.9^{\circ}C$ and 196.0 respectively. The Briere 2 and Lactin 2 modes were best fitted for all development stages. The distribution of completion of each development stage was explain relatively well that 2-parameter, 3-parameter and Logistic model except egg and pupal stage.

• Food Science of Animal Resources
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• v.31 no.4
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• pp.557-562
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• 2011

The study was performed to investigate microbial and physicochemical properties of domestic liquid eggs during cold storage. The liquid eggs used in the experiment were whole liquid, liquid egg yolks, and liquid egg whites. All samples were analyzed in summer and winter. The aerobic microorganisms were 1,270-83,300 CFU/g from non-sterilized liquid eggs produced in summer and their numbers increased from those produced in winter (ND, ~4,330 CFU/g). Total coliforms were not observed in non-sterilized whole liquid and non-sterilized liquid egg yolk regardless of season. Total coliforms from nonsterilized products were not detected in liquid egg whites during cold storage. Salmonella sp. was not observed in any of the liquid egg products. However, Pseudomonas sp., Pseudomonas geezennei, Pseudomonas otitidis, and Pseudomonas aeruginosa were identified by 16S rRNA from non-sterilized whole liquid eggs produced in summer. The pH and viscosity of whole liquid eggs and liquid egg whites were not different between the sterilized and non-sterilized treatments during cold storage. These results suggest that managing cross-contamination is necessary when non-sterilized liquid eggs are processed in summer.

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.278-283
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• 2010

Black plaice, Pleuronectes obscurus (Herzenstein), were collected and fertilized to observe egg development, temperature-related cleavage rates, and mitotic intervals (${\tau}_0$). Fertilized egg was demersal, adhesive, and did not contain oil globules. After 1.75 h, the blastodisc formed, and hatching took place 121 h after fertilization at $14^{\circ}C$. The hatched larvae were $3.5{\pm}0.16\;mm$ in total length. At higher temperatures, eggs developed faster and underwent further identical developmental processes. Additionally, ${\tau}_0$ and water temperature were strongly negatively correlated at all temperatures (Y=-2.6981X+98.767, $R^2$=0.9831, where Y is ${\tau}_0$, and X is temperature) for black plaice.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.676-683
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• 2023

The development of the egg, larvae, and juveniles of Acheilognathus macropterus from the Wicheon stream of Nakdonggang River was investigated for early life history characteristics. The fish used in the study were collected from Wicheon stream located in Bian-myeon, Uiseong-gun, Gyeongsangbuk-do. The fertilized egg was 1.88±0.09 mm (n=30) in long diameter and 1.34±0.06 mm (n=30) in short diameter. After fertilization at a water temperature of 20℃, the egg took 31 h and 40 min to hatch. Newly hatched larvae had an average total length of 3.92±0.13 mm (n=30) and possessed a yolk sac the mouth and anus were not developed. Twenty days after hatching, the postflexion larvae had an average total length of 8.08±0.29 mm (n=30), with the tail tip fully bent at 45° and began feeding. Thirty-three days after hatching, the number of fin stems reached an integer with an average total length of 15.0±1.08 mm (n=30). In this study, differences in the egg size, hatching time, melanophore development period, and distribution location were confirmed between A. macropterus and allied species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.380-386
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• 2007

Egg development and juvenile growth of the Pacific cod Gadus macrocephalus (Korean East Sea Population) were studied to increase fry production using mass cultivation. The eggs were rectangular and adhesive sinking type. The egg size and fertilization rate were 1.01-1.09 mm and 72.4%, respectively. The cumulative times for egg hatching at 3, 6, 9, and $12\;^{\circ}C$ were 600, 360, 240, and 192 hrs, respectively. The hatching rates at 3, 6, 9, and $12\;^{\circ}C$ were 60.2, 68.9, 62.5, and 40.6%, respectively. After 11, 45, and 90 days, the larvae grew to a total length of 5.46-5.99, 9.42-10.06, and 23.0-32.0 mm, respectively. At 100 days from hatching, they grew to an average of 30 mm with a 7.1 % survival rate. By 312 days, juveniles with a total length of 3.6 cm grew to a total length of 14.7-20.1 cm and a body weight of 38.4-73.9 g. The specific growth rates of total length and body weight of the juveniles were 0.50% and 1.12%, respectively.

• Journal of Life Science
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• v.19 no.9
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• pp.1309-1313
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• 2009

Endocrine disruptors are chemicals which can be found in our normal daily lives. Chemicals such as bisphenol A, DDT, benzophenone and phenylphenol can be easily ingested through plastic food containers and pesticides. Endocrine disruptors can be very harmful and toxic because they disrupt the normal function of the endocrine system. It has been reported that endocrine disruptions can cause fatal strikes in the cardiovascular, reproductive, and central nervous systems, and other parts of the body. Therefore we examined if benzophenone as an endocrine disruptor inhibits development in or induces malformation of chick embryos. Chick embryos which received a single injection of benzophenone ($1{\mu}g$/egg $\sim$ $500{\mu}g$/egg) via the yolk sac at designated times (6, 9, 12, 15, 18 and 21 days after incubation) were investigated. Body weight reduction was observed in middle doses ($40{\mu}g$/egg $\sim$ $60{\mu}g$/egg). High mortality rates and teratogenic signs such as abnormal wry beak and abnormal eyeballs were seen in high doses ($80{\mu}g$/egg $\sim$ $500{\mu}g$/egg). In conclusion, it is suggested that benzophenone induces malformation of chick embryos and seriously inhibits development.

• Journal of Life Science
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• v.10 no.1
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• pp.1-6
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• 2000

Larval development, adult longevity and oviposition of the beet armyworm, Spodoptera exigua H bner was studied at 16, 20, 25 and 3$0^{\circ}C$ with a 16L: 8D photoperiod. Egg hatchability of S. exigua was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. Egg period was the shortest at 3$0^{\circ}C$ and prolonged with decreasing temperature. Percent pupation was became higher at higher temperature form 23.2% to 94.0%. Developmental period of larva was the shortest at 3$0^{\circ}C$, but extended with decreasing temperature. Adult emergence ratio was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. The mean pupal period was 35.2, 14.4, 7.8 and 5.0 days at 16, 20, 25 and 3$0^{\circ}C$, respectively. Relationships between constant temperature and the developmental velocity of egg, larva and pupa were linear. Developmental threshold temperature seems to be 13.3 8$^{\circ}C$ for egg, 14.02$^{\circ}C$ for larva, 14.09$^{\circ}C$ for pupa, and 13.84$^{\circ}C$ for egg the adult. Estimated value of the total effective temperature for completing each stage was 36.89 day-degree for egg, 155.72 day-degree for larva, 79.20 day-degree for pupa, and 273.41 day-degree for egg to adult. Female longevity varied to temperature from 11.4 days at 16$^{\circ}C$ to 5.8 days at 3$0^{\circ}C$, and male longevity was longer than that of female. Preoviposition period was the shortest at 3$0^{\circ}C$, but prolonged with decreasing temperature. It was about 2.7 times longer at 16$^{\circ}C$ than that at 3$0^{\circ}C$. Number of eggs per female was the highest at $25^{\circ}C$, followed by 20, 30 and 16$^{\circ}C$.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.134-135
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• 1993

The purpose of this research is development of EGG system for quantitative assessment of laryngeal function using speech and electroglotto-graphic data. The designed EGG system is 4-electrodes system which excitation current source is supplied from 1st to 4th electrode. The output signal.: from 2nd and 3rd electrodes, which are motivated by frequency of excitation current source, are air-pressure waveforms from vocal folds. After demodulation process, we obtain pitch signals of the modulated waveforms by excitation current source through differentiator which cuts off frequency below 0.1Hz. Software processing methods were used as conventional pitch extraction methods, but the proposed system is designed to analog hardware in order to eliminate interferences from low formant frequency of speech. We will construct the discriminating database between pathological subjects and control groups on each case. Using the proposed 3 channel EGG system and LMS algorithm, it will be detected that the distinctive characteristics of laryngeal function of voiced region and other regions by EGG signals and LPC spectra.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.7
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• pp.922-928
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• 2001

There exists considerable evidence that steroid hormones are involved in the regulation of ovulation rate and oviductal development in poultry. However, the effect of steroid hormones on egg productivity of Korean Native Ogol Chicken (KNOC) has yet to be studied. Therefore, this study was performed to relate the expression of steroid hormones, especially progesterone ($P_4$) and estradiol ($E_2$), with egg productivity during the laying period. Egg production and egg weight of 70 KNOC were recorded from 20 to 60wk. Blood was taken every 10 wk and serum $P_4$ and $E_2$ were measured by radioimmunoassay. Based on egg productivity and steroid hormones levels up to 60 wk, chickens were divided into two groups, high and low. Compared to the low egg production group, a significantly higher expression of $P_4$ at 30 wk was detected in the high group. Moreover, egg production in the high $P_4$ group significantly differed from that in the low group at 30 wk. On the other hand, a Significant difference (p<0.05) in $E_2$ expression was found between high and low egg weight groups at 30 wk. Although a significant difference in egg weight between two groups by $E_2$ was not detected, the high $E_2$ group showed a higher level of egg weight than the low $E_2$ group except for 25 wk. In the comparison of ovary weight and small yellow follicle number, the group with high egg productivity and steroid concentration showed greater levels than the low group. Taken together, the results indicate that $P_4$ is related to egg productivity whereas expression of $E_2$ is associated with egg weight in KNOC.