• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.1
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• pp.1-7
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• 2009

Quality of seed in the mulberry silkworm, Bombyx mori (L.) is determined by many important factors, wherein unfertilized eggs play an important role. Unfertilization of eggs are caused by several reasons such as, abnormality in the sexual organs of the male and female, abnormal development of the micropylar end of the egg, unfavorable environmental conditions during spinning, cocoon preservation, imperfect handling of moths, mating, ovipostion, cold storing of pupae / moths and indiscriminate use of male moths etc. Though the presence of unfertilized eggs would in no way affect the fertilized ones and their quality directly, the frequency of their occurrence underrates the quality and brings down the hatching percentage. Lower the occurrence of unfertilized eggs, higher is the rating of seed quality. Of the various intrinsic and extrinsic factors and events involved in egg deposition of an adult silk moth, mating is an instinct and a biological obligation for the ultimate perpetuation of the species and a must to provide stimulus for oogenesis and bring about biochemical changes in the spermatophore of the silkworm in order to ensure the presence of sufficient number of normal sperms and testicular fluid in the female reproductive organ, activating ovulation and accelerating oviposition behavior and egg deposition. An attempt has been made in this article to briefly elucidate the characteristics of unfertilized eggs, causes of their occurrence and its impact as well as the significance in silkworm seed production.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.370-374
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• 2015

Pacific herring Clupea pallasii eggs were attached to the gill net in Korean coastal waters off Busan. To conservation and management the eggs attached to the gill net, we followed the natural hatching in coastal waters from five days after fertilization to the hatching finished, where the temperature was $9^{\circ}C$. The diameter of fertilized eggs was 1.24-1.55 mm (n= 50), and had a segmented pale yellow yolk, no oil globule. Natural hatching had started by 10 days after fertilization. Mass hatching occurred around 11-12 days after fertilization, most of eggs separated from the gill net. Therefore, when the Pacific herring eggs attached in gill net, should be natural hatching-induced in coastal waters during 12-14 days.

• Toxicological Research
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• v.14 no.3
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• pp.379-384
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• 1998

Endocrine disruptor is an exogenous substance that changes endocrine function and causes adverse effects at the level of the organism, its progeny, and/or (sub)populations of the organisms. Purported adverse effects are cancers, declines in reproductive health, developmental learning disabilities in humans, and declining populations, altered morphology, physiology or behavior in wildlife. In these days, expert groups on chemicals in IPCS, IFCS and OECD are intensively discussing the identification of endocrine disruptors and the proper management of those chemicals. In this study, we screened the endocrine disrupting effects of lead using fertilized eggs of Oryzias latipes. In brief, the eggs were exposed to lead with different concentrations at Ringer's solution, and the mortality, the incidence of deformation, the body movement and the hatching success were determined after incubation. The histological analysis of normal and deformed larvae was also carried out. Compared to control, the mortality and the heart rate of eggs and/or larvae increased, but the hatching success and the tail movement decreased. The morphological observation showed the asymmetrical deformation of larvae and the distortion of spinal cord. The absorption of the liquid in yolk sac was hindered. The adverse effects of lead in the ontogeny of fertilized eggs of Oryzias latipes seemed to be stronger in pH5.6 than in pH7.5 solution. In summary, lead showed adverse effects on the ontogeny of fish fertilized eggs plays critical role in regulating biological systems and controlling developmental processes as an endocrine disruptor.

• Journal of fish pathology
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• v.31 no.1
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• pp.9-13
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• 2018

We previously monitored nervous necrosis virus (NNV) in brain samples of artificially produced walleye Pollock (Gadus chalcogrammus) seedlings, with a low prevalence (1.8%, 1/55) but no clinical symptoms. Given that this virus is considered one of the most serious viral threats for almost all marine aquaculture fish species and characterized by both vertical and horizontal transmission, it would be interesting to monitor NNV in the fertilized eggs as well. We collected fertilized walleye pollock eggs from the farms located in Goseong during January to March, 2017. Approximately 50 mg of eggs were periodically taken from 4 each different batches, and 37 different pooled sample sets in total were made during sampling period. RNA was extracted from the eggs by using Trizol and cDNA was synthesized for RT-PCR for detecting NNV. Primers and PCR conditions are the same as previously described. As a result, NNV was not detected from any of the sample sets by one step PCR (0%, 0/37), suggesting NNV may not be a threat in walleye pollock aquaculture in Korea at present time. However, continuous monitoring for NNV should be conducted because introducing a new species into aquaculture industry involves potentials of disease outbreak and NNV is already known to cause outbreaks in gadoid fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.287-295
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• 2017

Egg development and morphological change of larvae of the Sakhalin sole Limanda sakhalinensis were studied by observing specimens obtained in a rearing experiment from fertilized eggs to the juvenile stage. The wild broodstock was collected in January 2010 and kept in a circular water tank (${\O}1.5{\times}1m$) at a temperature of $14.5{\pm}0.5^{\circ}C$. Fertilized eggs ranged from 0.72 to 0.82 mm ($0.77{\pm}0.07mm$, $mean{\pm}SD$) in diameter. The eggs were spherical, transparent and adhesive demersal. The egg yolk was divided from the oocyte 10 min after fertilization (AF), and an embryo was formed in 36 h AF. More than 50% of the eggs hatched within 133 h AF. The mouth and anus did not open until $3.5{\pm}0.25mm$ total length (TL). At 4, days after hatching (AH), the fish became larvae 3.7 to 4.2 mm ($4.0{\pm}0.36mm\;TL$), yolk absorption was completed and the mouth began to open. The left eye moved upward and the nostril moved to the right at 39 days AH. These post-larvae ranged from 8.0 to 9.9 mm TL ($8.9{\pm}1.33mm\;TL$). At 50 days AH, the fish became juveniles ($12.4{\pm}1.20mm\;TL$) There were 70-72 dorsal fin rays, 55-56 anal fin rays, 11 pectoral fin rays, and 6 ventral fin rays and the juveniles adopted a benthic life.

• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.91-94
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• 2003

Artificial insemination of cryopreserved semen is not practiced in broiler breeder industry although its benefit has been recognized for years. Thus, the present study explored the possibility of artificial insemination with cryopreserved semen in Ross broiler breeders. Sixty Ross female broiler breeders were artificially inseminated either with fresh or with cryopreserved semen pooled from five male Ross broiler breeders. On.e hundred eighty eggs were collected from each semen treatment and hatched. Fertility and hatchability of fertilized eggs collected from hens artificially inseminated with cryopreserved semen were 68.0 and 47.1％, respectively, compared to 88.3 and 87.2％ with fresh semen. Both unfertilized eggs and dead embryos during hatch were significantly (P<0.05) higher in the cryopreserved semen­treated group by approximately 2.7­ and 3.2­fold than the fresh semen­treated counterparts. the moderately low fertility and markedly low hatchability of fertilized eggs obtained from cryopreserved semen observed in this study may be of practical interests in broiler breeder industry and deserves further study.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.296-301
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• 2017

We conducted a study to 1) determine the indicators of gonadal maturity in male and female Korean walleye pollock Theragra chalcogramma for the purposes of artificial insemination; 2) establish the RNA/DNA ratio of mature eggs in this species; and 3) monitor the effect of refrigerated storage on egg viability and the motility of sperm collected from dead adult males. During the spawning season, the color of female gonads changed from orange to transparent, and that of male gonads changed from pale orange to milky white. The DNA content and RNA/DNA ratio of mature eggs were maintained without significant changes for approximately 6 h when eggs were preserved at $4^{\circ}C$. Sperm could be obtained from both milt and undiluted semen. Sperm obtained from milt ceased moving on the second day after isolation, while over 60% of sperm obtained from semen showed movement until the 13th day. Seven attempts were made to artificially inseminate mature eggs, of which two resulted in successful fertilization. The successful inseminations produced 94,000 and 5,000 fertilized eggs, respectively. This study shows that artificial insemination of walleye pollock is a viable strategy when natural propagation is not possible.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.131.2-131
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• 1996

No Abstract, See Full Text

• 대한생식의학회:학술대회논문집
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• 2001.11a
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• pp.118.2-118.2
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• 2001

• 대한생식의학회:학술대회논문집
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• 2002.05a
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• pp.86-86
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• 2002