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.

The objective of this study was to determine the mitotic intervals (τ0) of two consecutive cell divisions and synchronous embryonic cleavage in grass puffer, Takifugu niphobles at different water temperatures (18, 20, 22, and 24℃). The color of the fertilized egg was light yellowish. The egg type was demersal and unadhesive. Egg weight was 0.09±0.002 mg. The sizes of unfertilized eggs were smaller than fertilized eggs in major axis and minor axis at 20℃ (p<0.05). The size of the fertilized egg of 18℃ water temperature group at the blastodisc stage was the smallest (p<0.05), but no significant differences were observed in the other water temperatures group except 18℃ water temperature group (p>0.05). The first cleavage stages at 18, 20, 22, and 24℃ were at 75, 90, 105, and 120 mins, respectively. As water temperature was increased, embryonic development and formation time of the first cleavage furrow were accelerated. There were negative correlation between τ0 and water temperature for grass puffer (Y=–1.225X+70.05, R2=0.988, n=10, where Y was τ0 and X was temperature). This study confirmed that successful hatching of grass puffer was related to water temperature. Chromosome manipulation will be helpful for this species using cleavage frequency and τ0.

Asymmetric cell divisions play crucial roles during ascidian embryogenesis. In these processes, an FGF signaling is an essential inductive signal for establishing cell fate polarization, such as mesenchyme and notochord. It was well reported that the FGF signaling cascade is composed of FGF, FGF receptor, Ras, MEK, Erk and Ets. However, mechanisms of communication between the FGF and other signaling pathways and of integrated regulation of signaling pathways have remained largely unknown. In this study, we isolated HrS6K, a homologue of the S6K gene that belongs to the S6-H1 kinase of the ribosomal S6 kinase family, and HrNck1, a homologue of Nck1 gene that encodes an adaptor protein containing Src homology 2 and 3 domains, from the ascidian Halocynthia roretzi, to elucidate the mechanisms. Zygotic expression of HrS6K was initiated as early as the 16-cell stage. In the 64-cell stage embryos, expression of HrS6K was seen in mesenchyme precursor cells. The signal was detected in dorsal midline cells and mesenchyme clusters of the early tailbud embryos, and then down-regulated by the late tailbud stage. In adults, HrS6K mRNA was highly detected in muscle and stomach by QPCR method. On the other hand, HrNck1 transcripts are detected maternally. Zygotic HrNck1 mRNA was strongly expressed in mesenchyme clusters of the neurula, and in tail tip cells of the early tailbud embryos. These results suggest that HrS6K and HrNck1 are involved in formation of mesenchyme cells, which are specified by the FGF signaling.

Citrus is one of the major fruits produced in Korea. There are about 20 species mainly grown in Jeju Island, Korea. Four representative species, which are quite different in the shape of leaf and the taste of fruit, were selected and were used to profile the transcriptomes. These species are ‘Miyagawa Wase’ (C. unshiu Marcov.) satsuma mandarin, ‘Kiyomi’ (C. unshiu Marcov. × C. sinensis) mandarin hybrid, ‘Dangyuja’ (C. grandis) and ‘Natsudaidai’ (C. natsudaidai). Classification of the up-regulated and down-regulated genes using the Cluster of Orthologous Groups of proteins (COG) database reveals that the number of genes included in each group differed significantly among the four species. Several genes that showed significant differences in expression on the microarray were selected and their expression patterns were examined by reverse transcription- ploymerase chain reaction. Metabolic genes such as tyrosine decarboxylase and β-glucosidase ligase were found to be highly expressed in Miyagawa Wase, relative to other species. On the other hand, the expression level of mannose phosphate isomerase was lower in Miyagawa Wase. An efflux pump gene was found to be up-regulated in Kiyomi, whereas cinnamyl-alcohol dehydrogenase was down-regulated. β-carotene 15,15’-dioxygenase, which is involved in the vitamin metabolism, was up-regulated in Natsudaidai. Interspecific differentiations of gene expression are analyzed in terms of the metabolic pathways and their possible roles in citrus species.