시각피질에서 관찰되는 방향성 지도의 공간적 주기성 형성 기작에 대한 모델 연구

학위논문(석사) - 한국과학기술원 : 바이오및뇌공학과, 2016.2 ,[vi, 47 p. :]The orientation map is of great interest among functional maps in the visual cortex, but its developmental mechanism has been quite controversial among researchers. Recently, a theoretical model suggested that a moire interference pattern between ON and OFF retinal ganglion cell (RGC) mosaics can develop a quasi-periodic orientation map (Paik and Ringach, 2011), but the question remains how this interference pattern can generate a consistent spatial periodicity. Here, we suggest a developmental model in which a local interaction between cells can develop a long-range ordered hexagonal lattice mosaics, and a heterotypic interaction can control the alignment between ON/OFF mosaics. This provides an answer to above question about the development of a consistent periodicity in orientation maps. First, how a local repulsive interaction can generate a long-range ordered structure in RGC mosaics was examined. Previously, it was reported that the pairwise interaction point process (PIPP) model, in which cell positions are determined by a birth-and-death procedure that only considers a local interaction between homotypic pairs (Eglen et al., 2005) could not develop a long-range ordered structure in the mosaic (Hore et al., 2012). Here, rather than a birth-and-death step, it was assumed that cell positions can be gradually shifted by a local re-pulsive interaction between nearby cells. Thus, computer simulations were performed on the development of monotypic model RGC mosaics. It was confirmed that this local interaction model can develop a hexagonal pattern and also a long-range order periodicity in a monotypic mosaic. Next, it was assumed that there exists not only a homotypic interaction but also a het-erotypic repulsive interaction between ON/OFF mosaicsand thus, how this can affect the alignment between two mosaics was examined. By simultaneously simulating the develop-ment of both mosaics, the heterotypic interaction significantly alters the alignment between two mosaics. In addition, when the distance between two mosaics (inter-mosaic distance) was varied, it was observed that the alignment angle between two mosaics was restricted within a certain range of the inter-mosaic distance, which is required by the moir？ interference model for orientation map development. Additionally, the existence of a heterotypic correlation was also estimated in simulat-ed and observed mosaics. After development, if one mosaic is intentionally shifted slightly, the repulsive energy state will be destabilized. If the energy state is estimated for various shifts of one mosaic, it will show a band of higher energy state compared to the mosaics with-out any shifts and such band was observed in both the observed and simulated mosaics. This suggests that local interaction between heterotypic cells might have been applied during the development of observed RGC mosaics, which is opposite of the previous assumption in an-other model (Eglen et al., 2005). This dissertation suggests that a simple local interaction between RGCs can develop a long-ranged structure in the mosaic, and that when ON and OFF mosaics are developed with a heterotypic repulsive interaction within a certain range of distance between the layers, the alignment angle between the ON and OFF mosaics can be restricted, and this leads to a con-sistent spatial periodicity of the orientation map. To support above results, the existence of a correlation between heterotypic pairs in the observed mosaic was also estimated. Therefore, this model provides a complementary explanation of how an interference pattern in the retinal mosaic structure can be developed as a blueprint of cortical orientation maps.한국과학기술원 :바이오및뇌공학과

생쥐의 Mtch1 계열 유전자의 구조및 종간 진화적 유연관계분석

학위논문(박사) - 한국과학기술원 : 생물과학과, 2000.2, [ viii, 115 p. ]A brain-specific cDNA fragment from mouse was isolated by subtracting brain cDNAs with liver cDNAs. The cDNA fragment was revealed to encode a novel mitochondrial carrier from sequence similarity, named as Mtch1 (mitochondrial carrier homolog 1). The Mtch1 gene was expressed predominately in nervous system of 9.5 dpc mouse embryo and 10.5 dpc embryo and in adult brain, suggesting that the Mtch1 gene influence the early development of brain tissues. Several murine Mtch1 cDNA clones were obtained from brain cDNA library. The sequence analysis of the cDNA clones revealed two Mtch1 transcripts by alternative splicing of 51 bp as confirmed by RT-PCR. Two different putative Mtch1 proteins consist of 372 or 389 amino acids. About 20 Kb of the Mtch1 genomic sequence was assembled by connecting the overlapped sequences of several genomic clones. The gene was compromised of 13 exons and 12 introns with all the splice donor and acceptor sites conforming to the canonical GT/AG rule. The promoter, lacking TATA and CAAT boxes, harbored a CREB and six Sp1 binding sites. A CpG island was found in the promoter and the region surrounding translation start site. Southern blot analysis showed that the Mtch1 gene was single copy. The Mtch1 transcription was mainly initiated at site 118 bp upstream from the translation start codon. The Mtch1 gene was located on human chromosome 6p21 and 15.23 cM of mouse chromosome 17. The Mtch1 orthologs were identified in human, hamster, rat, Drosophila, Caenorhabditis elegans, and Bombyx mori from a comprehensive database analysis. Like murine Mtch1 cDNA, human MTCH1 cDNA potentially encode polypeptides with 372 or 389 and Drosophila mtch and Bombyx mtch were composed of 295 and 316 amino acids, respectively. Murine Mtch2 and its orthologs, the murine Mtch1 paralogs, were found in human, chicken, and zebrafish. The murine Mtch2 cDNA was comprised of an open eading frame of 303 amino acids. Two messages of Mtch2 gene were expressed constitutively...한국과학기술원 : 생물과학과

생쥐의 뇌 특이적 cDNA 절편의 분리 및 분석

학위논문(석사) - 한국과학기술원 : 생명과학과, 1993.2, [ vi, 46 p. ]In order to construct a mouse brain-specific cDNA library, a novel subtraction approach exploiting two different restriction endonucleases was designed. In the strategy, an EcoRI/NotI adaptor was attached to cDNAs copied from liver and brain mRNAs. And EcoRI digested brain cDNA pool was subtracted with a large excess of NotI cleaved liver cDNAs. Then, the subtracted brain cDNA population was cloned into EcoRI site of vector DNA. A clone obtained by a random selection from the subtracted population was turned out to have a cDNA fragment expressed abundantly only in brain tissure as confirmed by Southern blot analysis. Based on the partial DNA sequence analysis of both ends of this insert fragment, it only contains a part of the corresponding cDNA sequence. In addition, the DNA sequence suggests the presence of two possible translational initiation sites contain sequences with 70＼% homology to Kozak sequence, the ribosome entry site in the eukaryotic system. Therefor, it is likely that the cloned cDNA fragment represents the 5``region of the cDNA. Homology search revealed no significant homology to reported sequences, suggesting that this fragment is a novel sequence unknown as yet.한국과학기술원 : 생명과학과