• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.27.1-27.1
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• 2008

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.773-780
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• 2017

Objective: "Hatchability" is an important economic trait in domestic poultry. Studies on poultry hatchability focus mainly on the genetic background, egg quality, and incubation conditions, whereas the molecular mechanisms behind the phenomenon that some ducklings failed to break their eggshells are poorly understood. Methods: In this study, the transcriptional differences between the livers of normally hatched and assisted ducklings were systematically analyzed. Results: The results showed that the clean reads were de novo assembled into 161,804 and 159,083 unigenes (${\geq}200-bp$ long) by using Trinity, with an average length of 1,206 bp and 882 bp, respectively. The defined criteria of the absolute value of log2 fold-change ${\geq}1$ and false discovery rate${\leq}0.05$ were differentially expressed and were significant. As a result, 1,629 unigenes were identified, the assisted ducklings showed 510 significantly upregulated and 1,119 significantly down-regulated unigenes. In general, the metabolic rate in the livers of the assisted ducklings was lower than that in the normal ducklings; however, compared to normal ducklings, glucose-6-phosphatase and ATP synthase subunit alpha 1 associated with energy metabolism were significantly upregulated in the assisted group. The genes involved in immune defense such as major histocompatibility complex (MHC) class I antigen alpha chain and MHC class II beta chain 1 were downregulated in the assisted ducklings. Conclusion: These data provide abundant sequence resources for studying the functional genome of the livers in ducks and other poultry. In addition, our study provided insight into the molecular mechanism by which the phenomenon of weak embryos is regulated.

• Journal of Sericultural and Entomological Science
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• v.29 no.2
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• pp.15-23
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• 1987

The strain differences in larval walking behavior of 39 silkworm varieties, Bombyy mori, have been investigated. larval walking distance in silkworm varieties were remakably different. The walking distance was the longest in the matured larvae following the newly hatched larvae and in the other larval stage the distance was very short. The means of the walking distance in larval stages were as follows ; newly hatched larvae was 2.58cm, 3rd instar 0.72cm, 5th instar 1.18cm and matured larvae 2.94cm. The length of relative walking distances in each variety was not always in proportion to each larval stage. Therefore, the controlling factor of walking behavior was assumed to be different by the each larval stage. In the newly hatched larvae, 3rd instar and 5th instar larvae, the distribution range of walking distance was very broad in European races, narrow in Chinese races and medium in Japanese races. There was not much differences in the walking distance of mature larvae among European, Chinese and Japanese races.

• Journal of Embryo Transfer
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• v.26 no.2
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• pp.117-122
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• 2011

In this study, we examined the effectiveness of in vitro fertilization of porcine immature oocytes on the embryo development of blastocysts or hatched blastocysts and the number of cells according to the in vitro fertilization conditions. In the in vitro fertilization of in vitro matured porcine oocytes, there were no significant differences between treatment groups regarding fertilization rate, blastocyst rate, and embryo development of hatched blastocysts according to the storage periods of liquid sperm of 24, 48, and 72 hours. The embryo development rate of hatched blastocysts after the fertilization according to different spermatozoa concentrations ($0.4{\times}10^5$, $1.2{\times}10^5$, and $3.6{\times}10^5$ cells/ml) showed the highest rate in the group with a spermatozoa concentration of $1.2{\times}10^5$ cells/ml; in particular, this rate was significantly higher than that in the $0.4{\times}10^5$ cells/ml group (p<0.05). The total number of blastocysts cells as well as trophectoderms (TE) that developed in each treatment group were also significantly higher in the $1.2{\times}10^5$ cells/ml group than in any other groups (p<0.05). In contrast, the embryo development rate of blastocysts according to different co-incubation periods of sperm and oocyte (1, 3, and 6 hr) was high in the 6-hour group; in particular, the rate was significantly higher than that of the I-hour group (p<0.05). Furthermore, the total number of oocytes cells and TEs that developed was significantly higher in the 6-hour group than any other group (p<0.05). In this study, the most effective treatment conditions for porcine embryo development and high cell number were found to be as follows: a sperm storage period of less than 72 hours, a spermatozoa concentration of $1.2{\times}10^5$ cells/ml, and a 6-hour co-incubation period for sperm and ooocyte.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.394-400
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• 1998

Cryopreservation of embryos by vitrification is a simple method to preserve bovine embryos for subsequent embryo transfer, but embryonic viability after vitrification has been inconsistent and low compared with conventional slow freezing. The aim of the present study is to examine the effect of serum or serum albumin in a vitrification solution and epidermal growth factor(EGF) or fibroblast growth factor(FGF) on in vitro viability of bovine blastocysts frozen by vitrification. Bovine blastocysts were produced by in vitro maturation, fertilization of follicular oocytes and culture of embryos in a synthetic oviduct fluid medium(SOFM) containing BSA and 19 essential and nonessential amino acids. Blastocysts with excellent or good morphology were selected at 7 or 8 days after culture and utilized for vitrification. In experiment 1, blastocysts were vitrified in a solution containing semi-fetal calf serum(SFCS) or BSA(5 or 10mg/ml) and then their subsequent viabilities were examined by culturing thawed embryos in a SOFM containing BSA and 19 amino acids. Effect of EGF or FGF added to a SOFM containing polyvinyl alcohol(PVA) on the viability of vitrified-thawed blastocysts was investigated in experiment 2. BSA added at 5 or 10mg/ml to a vitrification solution showed significantly higher(p < 0.05) developmental rate to expanded and hatching blastocysts than SFCS, but there was no significant difference in the developmental rate to hatched blastocysts after thawing. Supplementation of a culture medium with EGF and/or FGF significantly increased(p < 0.05) embryo development to expanded blastocysts compared with control but showed no beneficial effect on the development to hatching or hatched blastocysts. Coculture of thawed embryos with granulosa cells in a TCM 199 containing 10% fetal calf serum(FCS) showed the highest developmental rate to expanded, hatching and hatched blastocysts among the groups tested. In conclusion, supplementation of a vitrification solution with BSA at 5mg/ml and culture of thawed blastocysts in a medium containing EGF and/or FGF can improve in vitro viability of bovine blastocysts frozen by vitrification.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1227-1231
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• 2002

A powerful tool for chicken transgenesis could be established by employing a germline chimera production through primordial germ cell transplantation. This study was conducted to examine whether foreign gene-transfected gonadal primordial germ cells (gPGCs) have a migration activity into the gonad after transfer to recipient embryos. In Experiment 1, gPGCs of Korean Ogol Chicken were retrieved from 5.5-day-old embryos and subsequently transferred to the dorsal aorta of 2.5-day-old White Leghorn embryos after being labeled with PKH26 fluorescent dye. To confirm migration activity after transplantation, recipient embryos were sacrificed and examined on 3 days after transfer. Sex determination was concomitantly undertaken to examine whether sex of recipient embryos could affect the migration activity of gPGCs. All of embryonic gonads examined showed positive signals with PKH26 fluorescence and W-chromosome specific band by polymerase chain reaction (PCR) was detected in male embryos when gPGCs with ZW chromosome were transferred to recipient embryos. In Experiment 2, retrieved gPGCs were transfected with LacZ gene-containing cytomegalovirus promoter ($pCMV{\beta}$) by electroporation and subsequently transferred to recipient embryos. LacZ gene expression was identified in the gonads of 6 or 10-day-old recipient embryos and hatched-chicks. A total of 20 embryos and 12 hatched-chicks were examined and 11 of them (10 embryos and one hatched chicken; 11/32=34.4%) expressed $\beta$-galactosidase, a marker substance of LacZ gene. The results of this study demonstrated that foreign gene-transfected gPGCs can migrate and settle down into the gonad after being transferred into the blood vessel of the recipient embryos. This established technique will contribute to developing a peer biotechnology for transgenic chicken.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.478-484
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• 2004

On 11 June 1991, eggs from the brood stock of small yellow croaker (Larimichthys polyactis) were artificially fertilized using the standard dry method and were hatched. Each of the fertilized eggs (1.1-1.2 mm in diameter) had an oil globule and was transparent and buoyant. The fertilized eggs hatched in a range of water temperatures $(17.5-20.3^{\circ}C)$ 44 hrs after fertilization. The total lengths of the newly hatched larvae were 3.1-3.3 mm, and these hatchlings had 31 myotomes (10+21). Melanophores and yellow-brown chromatophores were concentrated on the head, at the ventral part of the yolk, and in the middle of the tail. Four days after hatching, the larvae completely absorbed the yolk and became flexions of 5.1-5.5 mm in total length. Fifteen days after hatching, one spine (the anterior tip of the maxillary) appeared in the upper jaw and three spines developed at the upper parts of the eyes and on the posterior part of the head. At this stage, the larvae were approximately 8.3 mm long. Thirty-nine days after hatching, juveniles (1.9-3.4 mm in total length) had a pointed tail fin. By 66 days after hatching, the juvenile fish (about 4.0-6.5 mm in total length) were similar to adult fish in body shape. The larvae of L. polyactis could be distinguished from those of L. croacea by two distinct characteristics: the large number of vertebrae (28-29), and a relatively small bony ridge on the occipital region of the head.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.917-926
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• 2022

The green turtle Chelonia mydas has been designated as an endangered species globally due to its reduced population. Although C. mydas is not known to reproduce on the shores of the Korean peninsula, it has been listed as a protected marine species in South Korea. This study describes the first successful captive breeding of C. mydas in a commercial aquarium in South Korea and provides information on the early growth patterns of C. mydas hatched and reared in indoor facilities. C. mydas YS-B003 laid a total of 594 eggs in ten nesting events in the period December 2016-June 2017. Of these, 115 fertilized eggs from six events hatched successfully. The size of the newly hatched turtles differed significantly among nesting events. The hatchlings from the 8^th and 9^th nesting events were relatively smaller than those from the 3^rd and 5^th events. The rate of growth initially varied across the different events, but from the 1,000^th day, the inter-group variation disappeared. The present study provides useful information for future captive breeding of sea turtles in indoor facilities, which would contribute to the protection of these endangered sea turtle species.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.349-357
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• 1998

This study was to investigate whether the viability of Hanwoo IVM/IVF/IVC blastocysts was maintained after vitrification and thawing. In vitro produced Hanwoo blastocysts were vitrified by two-step method: equilibrated in EG20 for 3 min, and then exposed in EFS40 ［40% ethylene glycol (EG), 18% ficoll and 10.26% sucrose in mDPBS containing 10% FBS ］and vitrified in L$N_2$for 30 - 45 sec. After thawing, in vitro survival was assessed as the re-expanded and hatched rates at 24 hand 48 h, respectively. The results obtained in these experiments were summarized as follows: From the 12 replicates, 52.5% of Hanwoo blastocysts were produced in vitro at day 7 after IVF. When the effects of freezing solution to the embryo survival were examined, there is no significant toxicity in exposure (100.0, 73.8%) compared to that af control group (100.0, 87.0%). However, when embryos were vitrified, high survival (86.2, 55.4%) was obtained although it was significantly lower than those of exposure and control group (p＜0.05). When the in vitro survival of vitrified embryos according to developmental stage and culture day were examined, it showed that more advanced embryo stage exhibited a significantly higher survival rate irrespective of culture day (p＜0.05). Also, even in the same development stage, the in vitro survival of day 7 embryos (re-expanded: 75.0~87.5%, hatched: 21.4~66.7%) was higher than those of day 8 embryos(re-expanded: 58.6~78.3%, hatched: 10.3~52.2%). Therefore, these results suggested that in vitro produced Hanwoo blastocysts can be successfully cryopreserved by simple two-step vitrification method using EFS40 freezing solution, particularly at the expanded and early hatching blastocyst stage regardless of embryo culture duration (day 7 or day 8 after IVF).

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.231-238
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• 1999

The objective of this study was to examine the effect of developmental stage and embryo age of in vitro produced bovine blastocysts after vitrification and thawing. In vitro cultured day 8 blastocysts after IVF were equilibrated 20% ethylene glycol (EG) for 3 min. and were vitrified using EFS40, which is consisted of 40% EG, 18% ficoll, 0.3M sucrose and 10% FBS added in mDPBS for 30 sec. before being plunged into $LN_2$. Also, survival in vitro was assessed by re-expansion and hatching or hatched at 24 hand 48 h postwarming, respectively. The results obtained in these experiments were summarized as follows; 1) When the embryos were cultured for 8 day after IVF, 41.0% of the cleaved embryos developed to the blastocysts (early; 7.6%, expanded; 22.9%, hatching; 4.6% and hatched; 5.9%). 2) When the embryos were exposed or vitrified to the freezing solution, the re-expansion of vitrified embryos (73.3%) was significantly lower than that of control and exposed embryos (100, 97.0%) (p<0.05). But the formation rate of hatching or hatched blastocysts of vitrified embryos (66.7, 46.7%) at 48h after thawing was similar to that of exposed embryos (66.7, 39.4%) but not control (100, 100%) (p<0.01). However, in the total cell numbers of those developed hatched blastocysts, there were not significantly different among the treatment groups. 3) When the embryo survival rates by different developmental stage were examined, the re-expansion was not different among the groups $(64.5{\sim}75.6%)$. After warming 48 h, the hatching and hatched formation of early blastocysts (25.8, 9.7%) was significantly lower than those of expanded (69.7, 39.4%) and hatching blastocysts (53.3, 43.3%) (p<0.05). 4) In addition, when the expanded blastocysts at day 7, 8 and 9 were vitrified, the re-expansion of day 8 and 9 embryos was significantly lower than that of day 7 (day 7; 93.9%, day 8; 75.8% and day 9; 87.5%) (p<0.05). However, the rates of development to hatched blastocysts were no difference among the groups (day 7; 36.4%, day 8; 36.4% and day 9; 31.3%). These results suggested that in vitro produced expanded or hatching blastocysts can be efficiently cryopreserved by the two-step vitrification method using EFS40.