Ixeris dentata is a typical oriental herb. It is a widely distributed perennial in Korea, Japan and China, which belongs to the Compositae Family. The whole plant of I. dentata has been used for the treatment of pneumonia, contusion, tumor and hepatitis.

Human embryonic stem (ES) cells are derived from the inner cell mass of the preimplantation embryo. Human ES cells have the capacity to differentiate into various types of cells in the body. Human ES cells are indefinite source of cells for cell therapy in various degenerative disorders including neuronal disorders. Directed differentiation of human ES cells is a prerequisite for their clinical application. The objective of this study is to develop the culture condition for the derivation of neural precursor cells from human ES cells. Neural precursor cells were derived from human ES cells in a stepwise culture condition. Neural precursor cells in the form of neural rosette structures developed into neurospheres when cultured in suspension. Suspension culture of neurospheres has been maintained over 4 months. Expressions of nestin, soxl, sox2, pax3 and pax6 transcripts were upregulated during differentiation into neural precursor cells by RT-PCR analysis. In contrast, expression of oct4 was dramatically downregulated in neural precursor cells. Immunocytochemical analyses of neural precursor cells demonstrated expression of nestin and SOX1. When induced to differentiate on an adhesive substrate, neuro-spheres were able to differentiate into three lineages of neural systems, including neurons, astrocytes and oligo-dendrocytes. Transcripts of sox1 and pax6 were downregulated during differentiation of neural precursor cells into neurons. In contrast, expression of map2ab was elevated in the differentiated cells, relative to those in neural precursor cells. Neurons derived from neural precursor cells expressed NCAM, Tuj1, MAP2ab, NeuN and NF200 in immunocytochemical analyses. Presence of astrocytes was confirmed by expression of GFAP immuno-cytochemically. Oligodendrocytes were also observed by positive immuno-reactivities against oligodendrocyte marker O1. Results of this study demonstrate that a stepwise culture condition is developed for the derivation of neural precursor cells from human ES cells.

원형질체 융합에 의한 화합성 및 불화합성 종간 체세포잡종을 얻었다. 화합성 종간인 Pleurotus ostreatus 와 P. florida 의 융합체는 이질핵체 (heterokaryon) 를 형성하였고, 불화합성 종간인 P. cornucopiae + P. florida , P. ostreatus + Ganoderma applanatum, P. florida + Ganoderma lucidum, 그리고 P. ostreatus + Flammulina velutipes 는 합핵체(synkaryon) 를 형성하였다. 이질이핵체는 동일한 양상의 자실체를 형성하는데 비해 합핵체는 유사분열상의 꺽쇠연결체 형성, 한쪽 친과 유사한 자실체 형성, 비정상적 유전형질 분리 및 유전자재조합 현상을 나타내었다. 화합성 및 불화합성 계통간 융합체의 RAPD 분석결과 화합성 종간 융합체는 동일한 DNA 패턴을 나타내었고, 불화합성 종간 융합체는 한쪽 친과 유사한 DNA 양상이면서 비양친 DNA 밴드도 형성하였다. 합핵체의 패턴은 microgenome insertion type 과 macrogenome insertion type 으로 구분되었다. 합핵체의 자실체 발생은 융합 모균주 양친의 자가임성에 의존하는데 이는 느타리의 동형핵체 자가임성과 유사한 양상이었고, 교배형 전환과 관련이 있는 것으로 사료된다. 여기서는 이러한 관점에서 논할 것이다.