• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1573-1579
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• 2018

Transcriptional gene silencing is regulated by the chromatin structure, which is by various factors including histones. Saccharomyces cerevisiae contains transcriptionally silenced regions such as telomeric regions and hidden mating (HM) loci. The positively-charged amino acids on the histone H4 tail were reported to be critical for the telomeric silencing in yeast, by interacting with Dot1, a specific methyltransferase for the $79^{th}$ lysine on histone H3. However, Dot1 did not affect gene silencing within HM loci, but whether the positively-charged amino acids on the H4 tail affect HM silencing has not been defined. To elucidate the function of the H4 tail on HM silencing, we created several MATa-type yeast strains bearing the substitution of arginine with alanine or lysine on the histone H4 tail and checked the sensitivity of MATa-type yeast to alpha pheromone. The arginine point mutants substituted by alanine (R17A, R19A, and R23A) did not show sensitivity to alpha pheromone, but only two arginine mutants substituted by lysine (R17K and R19K) restored the sensitivity to alpha pheromone-like wild type. These data suggested that the basic property of arginine at $17^{th}$ and $19^{th}$ positions in the histone H4 tail is critical for maintaining HM silencing, but that of the $23^{rd}$ arginine is not. Our data implicated that the positive charge of two arginine residues on the histone H4 tail is required for HM silencing in a manner independent of Dot1.

• 산업경영시스템학회지
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• 제41권3호
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• pp.186-193
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• 2018

Modern manufacturing industries is to produce both precise and robust mechanical parts without failure while they are in service. In order to prevent a part failure for its lifetime, a mechanical design for a part should be examined on a basis of mechanical simulation. A nozzle plate, being a key part in steam engines, changes flow directions of steam in a turbine used in power plant. This paper is to the design and test for part safety and durability. Currently, nozzle plates are fabricated by welding nozzles to their plates. Welding causes some defects on the used materials while they are being manufactured. Another major defect is un-even pitches between welded nozzles. Welding causes phase changes because of high melting temperature of metal. This leads to decay on the welding spots, which weakens their structural strength and then, may lead to early damages on mechanical structures. This research proposes assembly-typed nozzle plate without welding. From the beginning, nozzle and plate are designed for insertion-typed assembly. Nozzle head and foot are designed in accordance with the grooves on outer ring and inner ring of a plate to make mating surfaces. Then the nozzle plate should be proved for structural and fatigue safety before they are put in manufacturing. This research adopts commercial softwares for modeling and mechanical simulation. The test result shows that the design with smaller mating area and deeper insertion produces higher safety in terms of structure and durability. From the conclusion, this paper proposes the assembly-typed nozzle plate to replace the welding typed.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.191-191
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• 2022

Heterostyly continues to fascinate evolutionary biologists interested in heredity, evolution, breeding, and adaptive function. Polymorphism demonstrates how simply inherited developmental changes in the location of plant sexual associations can have important consequences for population pollination and mating biology. In contrast to homozygous self incompatibility, only a small number of mating phenotypes can be maintained in the population because insect pollinators have limitations in achieving multiple segregation sites for pollen deposition. Field studies of pollen tube growth have shown that reciprocal style-stamen polymorphisms function to increase the capacity of insect-mediated cross-pollination. The genetic pattern of style morphs is well established in various taxa, but despite recent advances, the identity, number, and structure of the genes controlling the heteromorphic syndrome have been poorly elucidated. The phenomenon of heterostyly in buckwheat has been controlled by gene complex concentrate to S-locus. Homomorphic autogamous buckwheat strains were established by the interspecific hybridization. Backcrossing of this line to the common buckwheat (pin) and selecting homostylar progenies made it possible to introduce the self-compatible gene into common buckwheat. In the result, we obtained the BC₉F₂ generation, and defined the strong linkage between flower type and self-incompatibility by microscopic observation of pollen tube growth. This finding suggests that self-incompatibility character is not controlled by one gene. Moreover, we defined the strong linkage between flower type and self-incompatibility. It strongly supports the S supergene theory. Therefore, we have plan to elucidate the heterostyly self-incompatibility by using molecular genetics, proteome analysis and apply to exploitation of buckwheat improvement. In near future, the expression of heterozygous syndromes in genus Fagopyrum with single isolated heterozygous species may provide clues to early stages of polymorphic assembly and shed light on evolutionary models of heterozygous strains.

• The Korean Journal of Ecology
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• 제17권3호
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• pp.299-310
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• 1994

종 내의 클론 상호작용은 개체군 구조에 중요한 영향을 미친다. 본 연구는 클론간의 경쟁에 의해 개체군 내에서 진화적 변화가 일어날 수 있는 가를 조사하고, 균일한 실험실 배양 조건에서 어떻게 다양한 클론이 진화하는지를 밝히고자 하였다. 자원소비율과 교배형이 다른 Polysphondylium pallidum의 클론들이 선택되었다. 실험은 T0에서 T4까지 4번의 시간 간격을 두고 시행되었다. 접종 후 자실체를 수확할 때까지의 한 번의 실험기간은 10~14일 정도 소요되었다. T0의 50개의 클론으로부터 일련의 실험기간 T1, T2, T3, T4에서 50 클론이 두 세트씩 만들어졌다. 개체군들의 자원소비율 변동은 T0와 두세트의 T4 클론들간에 비교되었다. 각 클론은 실험 시작 후 48~56세대가 지난 후에도 균일하고 제한된 Cerophyl 배지 환경에서 다양한 자원 소비율 즉, 다양한 생장율을 보였다. 생장율이 다른 다양한 클론은 서식처가 이질적인 토양 미세 환경 뿐만 아니라 한 장소의 균질한 배양 접시 속에서도 공존 할 수 있었다. 높은 클론 다양성은 한 개체군내의 클론에서 다른 클론을 만날 기회를 제공해 주었고 개체군내의 클론 경쟁이 활발히 일어났다. T0에서 T4까지의 총 실험 기간동안 교배형 I이었던 37개의 클론중에서 한 개체군의 31개가 교배형 II로 바뀌어 클론간에 일어난 경쟁배타율은 0.838이었다. 각 교배형의 출현 빈도는 연속적인 다음 세대마다 0.93~1.29% 만큼 바뀌었다. 2.6X108밀도의 박테리아를 먹이로 제공해 준 실험실 환경에서 한 세대가 지날 때 마다 한 클론에서 다른 클론으로 변화하는 진화적 변화확률이 1.26~1.75%라는 것을 의미한다.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1440-1447
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• 2002

Adhesion of a hemispherical tip to the flat surface in nano-structures is simulated using the molecular dynamics technique. The tip and plates are modeled with the Lennard-Jones molecules. The simulation focuses on the deformation of the tip. Detailed descriptions on the evolution of interaction force, the energy dissipation due to adhesion hysteresis, the forma- tion-growth-breakage of adhesive junction as well as the evolution of molecular distribution during the process are presented. The effects of the tip size, the maximum tip approach, the tip temperature, and the affinity between the tip and the mating plate are also discussed.

• 생명과학회지
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• 제9권4호
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• pp.460-465
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• 1999

In the giant freshwater prawn Macrobrachium rosenbergii, the paired testes were united by the testes bridge in a H-shape. During mating male discharged two hemispermtophores from right and left genital pore and they were joined and formed a compound spermatophore in peach shape. Hemispermatophore was considered to be produced at proximal and middle vas deferens region. The compound spermatophore consisted of an eosinophilic inner matrix, a basophilic outer matrix and paired sperm mass burried in the basophilic matrix. The size of compound spermatophore was 6.4∼ 9.3 mm in length and 2.4∼5.1 mm in width regardless of carapace length. After the spermatophore was deposited on female's ventral sternum behind of 5th pereiopod, it was moved to the ventral surface of 3rd and 4th pereiopods by means of the beating of male's 1st and 2nd pleopods.

• The Korean Journal of Ecology
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• 제22권6호
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• pp.349-354
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• 1999

The spatial distributions of allelic frequencies and ecological traits by randomization were studied in the natural population of two species (Pinus rigida and Pyrola japonica). Both species showed significant positive spatial autocorrelation as measured by Moran's I. In P. rigida, the genetic similarity was shown in individuals within up to a scale of 18 m distance and this is partly due to combination of pollen and seed dispersal by wind or men. In P. japonica, significant spatial autocorrelation was consisted of a scale of 8 m intervals. These population structure in the distribution of allelic frequencies is related to mating systems such as outcrossing and vegetative spread. The results also indicate that positive species associations between P. rigida and P. japonica can occur when both species select the same habitat or require the same environmental conditions.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.144-148
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• 1999

The relationship between oxidation and sliding wear behavior of Fe-28 at%. Al alloys with B2 ordered structure has been investigated. Sliding wear tests of the alloys have been carried out under various environmental conditions using a pin-on-disk wear tester. The wear rate of the ordered alloys in an oxygen atmoshpere was found to be much lower than in an oxygen atmosphere showed that Fe2O oxides formed on the wearing surface. The oxide layer prevented direct contact of the two mating materials and therefore improved wear resistance of the Fe-Al intermetallic alloy. It was found that the surface Al2O3 oxide layer which provides good oxidation resistance and improved mechanical properties broke down easily and didnot function properly as an oxidation barrier.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.731-736
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• 2000

An optimal design method is adopted for a spacer grid in nuclear power plant. It is made of punched sheet metal process, functioning as springs and dimples supporting fuel rods. For stress analysis of the assembled fuel rod support, a typical cell out of the repeated pattern in the assembly is modeled using 4-node shell elements. A commercial code, ABAQUS, is used for detailed analysis of contacting phenomena with friction. For the optimization, design varibles are taken from geometric parameters representing the shape of the bent leaf spring part and mating contact region with fuel rod. Objective function is considered in relation to mechanical functions and durability. Maximum yon Mises stress is considered in relation to constrained contact stress.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.180-183
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• 2002

Pseudomonns putida BCNU171 had the tolerant ability to several other organic solvents headed by toluene and xylene. Several mutants were made by mating of BCNUl71, pJFF350 to clarify the structure tolerance gene related. From this mutants the 7 of mutants related with toluene sensitive mutants were selected. pBCNUT-2, pBCNUT-4, pBCNUT-9 was transformed, and from this separated plasmid DNA sequences the gene having high homology was searched. In the case of toluene sensitive mutant it was todX gene (pBCNU4) related with cell membrane, ttgE gene (pBCNU2, pBCNU9) and ttgF gene (pBCNU2, pBCNU9).