• 한국수정란이식학회지
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• 제18권1호
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• pp.61-68
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• 2003

본 실험은 개의 인공수정에 사용할 신선정액, 그리고 동결정액을 이용한 자연교미와 발정유도된 실험견에 인공수정시 임신율과 산자수를 검증하여 그 효율성을 조사하였다. 1. 개의 인공수정시에 자연발정, clomifene, bromocriptine 단독 투여 그리고 GnRH + bromocriptine/GnRH 혼합 투여에 따른 발정유도방법은 임신율과 산자수에 영향을 미치지 않는 것으로 나타났으며, 신선정액을 이용한 인공 수정방법은 자연교미방법과 유사한 임신율과 산자수를 보였으나, 동결정액을 이용한 인공수정 시에는 비교적 낮게 나타났다. 2. 자연발정 유도군 또는 clomifen, bromocriptine 단독 투여군, GnRH + bromocriptine/GnRH 병용 투여로 발정이 유도된 암캐를 자연교배시 생산된 총 산자수는 54두, 신선정액을 이용한 인공수정에서는 50두로 유의적(P<0.05)인 차이가 없었고, 동결정액을 이용한 인공수정에서는 35두를 분만하여 자연교배에 비해 유의적(P<0.05)으로 총 산자수가 적었다. 본 실험의 결과에서 무발정견에 호르몬을 투여하여 발정을 유도시켜 수정을 해도 수태율과 산자수는 영향을 미치지 않으며, 신선정액에 의한 인공수정과 자연교배 시의 수태율과 산자수에는 차이가 없으나, 동결정액에 의한 인공수정 시에는 수태율과 산자수가 낮아짐을 알 수 있었다.

• 식물조직배양학회지
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• 제27권6호
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• pp.423-428
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• 2000

In 1997 when cloned sheep Dolly and soon after Polly were born, it had become head-line news because in the former the nucleus that gave rise to the lamb came from cells of six-year-old adult sheep and in the latter case a foreign gene was inserted into the donor nucleus to make the cloned sheep produce human protein, factor IX, in e milk. In the last few years, once the realm of science fiction, cloned mammals especially in livestock have become almost commonplace. What the press accounts often fail to convey, however, is that behind every success lie hundreds of failures. Many of the nuclear-transferred egg cells fail to undergo normal cell divisions. Even when an embryo does successfully implant in the womb, pregnancy often ends in miscarriage. A significant fraction of the animals that are born die shortly after birth and some of those that survived have serious developmental abnormalities. Efficiency remains at less than one % out of some hundred attempts to clone an animal. These facts show that something is fundamentally wrong and enormous hurdles must be overcome before cloning becomes practical. Cloning researchers now tent to put aside their effort to create live animals in order to probe the fundamental questions on cell biology including stem cells, the questions of whether the hereditary material in the nucleus of each cell remains intact throughout development, and how transferred nucleus is reprogrammed exactly like the zygotic nucleus. Stem cells are defined as those cells which can divide to produce a daughter cell like themselves (self-renewal) as well as a daughter cell that will give rise to specific differentiated cells (cell-differentiation). Multicellular organisms are formed from a single totipotent stem cell commonly called fertilized egg or zygote. As this cell and its progeny undergo cell divisions the potency of the stem cells in each tissue and organ become gradually restricted in the order of totipotent, pluripotent, and multipotent. The differentiation potential of multipotent stem cells in each tissue has been thought to be limited to cell lineages present in the organ from which they were derived. Recent studies, however, revealed that multipotent stem cells derived from adult tissues have much wider differentiation potential than was previously thought. These cells can differentiate into developmentally unrelated cell types, such as nerve stem cell into blood cells or muscle stem cell into brain cells. Neural stem cells isolated from the adult forebrain were recently shown to be capable of repopulating the hematopoietic system and produce blood cells in irradiated condition. In plants although the term$\boxDr$ stem cell$\boxUl$is not used, some cells in the second layer of tunica at the apical meristem of shoot, some nucellar cells surrounding the embryo sac, and initial cells of adventive buds are considered to be equivalent to the totipotent stem cells of mammals. The telomere ends of linear eukaryotic chromosomes cannot be replicated because the RNA primer at the end of a completed lagging strand cannot be replaced with DNA, causing 5' end gap. A chromosome would be shortened by the length of RNA primer with every cycle of DNA replication and cell division. Essential genes located near the ends of chromosomes would inevitably be deleted by end-shortening, thereby killing the descendants of the original cells. Telomeric DNA has an unusual sequence consisting of up to 1,000 or more tandem repeat of a simple sequence. For example, chromosome of mammal including human has the repeating telomeric sequence of TTAGGG and that of higher plant is TTTAGGG. This non-genic tandem repeat prevents the death of cell despite the continued shortening of chromosome length. In contrast with the somatic cells germ line cells have the mechanism to fill-up the 5' end gap of telomere, thus maintaining the original length of chromosome. Cem line cells exhibit active enzyme telomerase which functions to maintain the stable length of telomere. Some of the cloned animals are reported prematurely getting old. It has to be ascertained whether the multipotent stem cells in the tissues of adult mammals have the original telomeres or shortened telomeres.

• 한국가축번식학회지
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• 제20권2호
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• pp.207-214
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• 1996

본 연구는 미세조작된 수정란의 초급속 재동결 후 발생능을 조사하기 위해서 수행하였다. 먼저 4세포기 생쥐 수정란으로부터 할구세포 한 개를 떼어내고 이들 수정란을 동결액에 넣어 상온에서 2.5분간 평형시킨 다음, 0.25ml straws에 넣어 곧바로 액체질소에 침지시켰다. 4세포기 수정란의 동결액으로는 4.0M(ethylene glycol 및 0.25M sucrose가 함유된 dPBS를 사용하였따. 상실배기 수정란의 동결을 위해서는 항동해제로 4.0M ethylene glycol 대신에 5.0M glycerol을 사용하였다. 융해후 biopsied 4세포기 수정란을 M16 배양액에서 상실배기까지 발달시킨 다음 상실배기용 동결액을 이용하여 초급속 재동결을 실시하였다. 재동결융해 후 발달한 biopsied 배반포기 수정란을 대리모에 이식하여 이들 수정란의 생존성을 검토하였다. 제1차 동결후 biopsied 수정란의 체외발달률은 78%로서 정상적인 수정란의 발달율(91%) 보다 낮은 성적으로 보여주었으나 (P<0.01), 이들 수정란의 이식 후 임신률은 각각 25 및 30%로서 두 실험군간에 차이가 인정되지 않았다. 그리고 biopside 상실배기 수정란의 초급속 재동결후 체외 발달률 및 임신률은 각각 89와 27%로서 biopsied 되지 않은 수정란의 성적 (각각 95 및 28%)과 유사하였다. 이러한 결과를 종합하여 볼 때, 본 연구에서 사용된 초급된 재동결 과정이 미세조작된 생쥐수정란의 생존성에 영향을 미치지 않는 것으로 나타났다.

• Clinical and Experimental Reproductive Medicine
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• 제29권4호
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• pp.269-278
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• 2002

Objective s: Chromosome aneuploidy is associated with recurrent abortion and congenital anomaly and genetic diseases occur repeatedly in the specific families. Preimplantation genetic diagnosis (PGD) can prevent aneuploidy or genetic disease by selecting normal embryos before implantation and is an alternative to prenatal diagnosis. The aim of this study is to assess the outcome of PGD cycles by using FISH or PCR, and to determine the clinical usefulness and values in patients with risk of chromosomal aneuploidy or genetic disease. Materials and Methods: From 1995 to Apr. 2001, a total of 108 PGD cycles in 65 patients with poor reproductive outcome were analyzed. The indications of PGD were translocation (n=49), inversion (n=2), aneuploidy screening (n=7), Duchenne muscular dystrophy (n=5) and spinal muscular atrophy (n=2). PGD was applied due to the history of recurrent abortion, previous birth of affected child or risk of aneuploidy related to sex chromosome aneuploidy or old age. Blastomere biopsy was performed in 6$\sim$10 cell stage embryo after IVF with ICSI. In the single blastomere, chromosome aneuploidy was diagnosed by using FISH and PCR was performed for the diagnosis of exon deletion in DMD or SMA. Results: The FISH or PCR amplification was successful in 94.3% of biopsied blastomeres. The rate of transferable balanced emb ryos was 24.0% in the chromosome translocation and inversion, 57.1% for the DMD and SMA, and 28.8% for the aneuploidy screening. Overall hCG positive rate per transfer was 17.8% (18/101) and clinical pregnancy rate was 13.9% (14/101) (11 term pregnancy, 3 abortion, and 4 biochemical pregnancy). The clinical pregnancy rate of translocation and inversion was 12.9% (11/85) and abortion rate was 27.3% (3/11). In the DMD and SMA, the clinical pregnancy rate was 33.3% (3/9) and all delivered at term. The PGD results were confirmed by amniocentesis and were correct. When the embryos developed to compaction or morula, the pregnancy rate was higher (32%) than that of the cases without compaction (7.2%, p<0.01). Conclusions: PGD by using FISH or PCR is useful to get n ormal pregnancy by reducing spontaneous abortion associated with chromosome aneuploidy in the patients with structural chromosome aberration or risk of aneuploidy and can prevent genetic disease prior to implantation.