Long interspersed elements (LINEs) are transposable elements that proliferate within eukaryotic genomes, having a large impact on eukaryotic genome evolution. LINEs mobilize via a process called retrotransposition. Although the role of the LINE-encoded protein(s) in retrotransposition has been extensively investigated, the participation of host-encoded factors in retrotransposition remains unclear. To address this issue, we examined retrotransposition frequencies of two structurally different LINEs—zebrafish ZfL2-2 and human L1—in knockout chicken DT40 cell lines deficient in genes involved in the non-homologous end-joining (NHEJ) repair of DNA and in human HeLa cells treated with a drug that inhibits NHEJ. Deficiencies of NHEJ proteins decreased retrotransposition frequencies of both LINEs in these cells, suggesting that NHEJ is involved in LINE retrotransposition. More precise characterization of ZfL2-2 insertions in DT40 cells permitted us to consider the possibility of dual roles for NHEJ in LINE retrotransposition, namely to ensure efficient integration of LINEs and to restrict their full-length formation.

Stress distribution along a tool rake face were measured directly in the orthogonal machining of various metals. The method of measurement was based on the use of a composite tool which was divided into two parts parallel to a cutting edge in order to measure separately the force acting on one section of the tool. The stress distributions under actual cutting conditions were revealed, and the relationship between the nature of stress distribution and the mechanical properties of work material was clarified. It was ascertained that the nature of stress distribution was closely connected with the strain hardening index of work material and the frictional coefficient between tool and material.

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This research deals with the development of a simple and practical method for manufacturing high-aspect-ratio (height/width) micro-parts and three-dimensional micro-parts. The desired product shape is obtained by writing along the contour of the product on the surface of a liquid photopolymer using a focused UV laser beam. The written pattern then becomes solid so as to produce a solidified polymer mold or structure. This paper examines the effect of physical parameters such as wavelength of laser beam, focal length of lens, absorption coefficient and writing speed on the shapes of the solidified polymer. The examination is done theoretically, and the optimum conditions to produce high-aspect-ratio micro-parts and three-dimensional micro-parts are also verified. Using these conditions, various microstructures are produced.

This research work deals with the methods for manufacturing high aspect ratio micro mechanical parts by using UV photopolymer. In the first method, polymer structures are produced using a mask-based method. And the second i s a direct focused UV laser beam writing method. The irradiated portion of the liquid photopolymer i s solidified and i t becomes a polymer structure. At first, the solidified shape of the polymer i s examined in each method and the optimum conditions to produce high aspect ratio structures are verified. Next, the comparison of the both methods are made. At l a s t , examples o f structures that have been produced using the methods described are shown.

Botryococcus braunii strain Austin and strain Berkeley cultured under the same conditions contained 27.4 g and 34.0 g of lipids per 100 g of dry alga, respectively. The lipids in the former strain were 25.5% hydrocarbons, 58.8% other nonpolar lipids, and 15.7% polar lipids, and those in the latter strain were 71.6%, 9.2%, and 19.2%, respectively. Distinct differences were also observed in the components of the nonpolar and polar lipids, especially in the latter, between the strains. The fatty acid composition of the nonpolar lipid fraction in Austin strain was unique, oleic acid being 81 % of the total acids.The colonial microalga Botryococcus braunii is a freshwater autotrophic species belonging to the Chlorophyceae and is known to produce unusually high levels of liquid hydrocarbons. The alga has been proposed as a renewable source of fuels from recent concern for future energy requirements. It occurs throughout the world in a wide variety of climates and includes several strains which are classified into two races, A and B.ll The A race accumulates linear olefins, odd numbered from 23 to 31, chiefly CZ7 , CZ9 ' and C31 dienes or trienes, whereas the B race produces polyunsaturated triterpenes of the general formula CnH2n-10, n = 30 ~ 37, termed botryococcenes. 1 -4) These findings suggest that the same strain is unable to yield successively the two types of hydrocarbons contrary to previous proposals. 5 ) Numerous reports have been published regarding hydrocarbons of this alga in relation to production and composition under different growth conditions,4-10) their chemical structures,Z,1l-15) and biosynthesis.1 6 -1 9 ) Largeau et al. 16J showed that [9,1O-3H]-palmitic acid was rapidly incorporated into the A race hydrocarbons and Templier et al.17) indicated that [1O-14C]-0Ieic acid was an efficient precursor of the hydrocarbons. These fatty acids seem to be key intermediate metabolites in the biosynthesis from carbon dioxide to alkadienes and trienes.Douglas et aeO) reported that fatty acids of a natural winter bloom of B. braunii Kiitzing belonging to the B race ranged from C 14 to C 30 , palmitic, oleic, octacosenoic acids being the major components. To our knowledge, however, no other information is available concerning the fatty acid composition of B. braunii.Such a situation prompted us to investigate lipid composition of this alga. In this study, we have chosen two B. braunii strains, one each from the A and B races, and compared their lipids. We report here their nonpolar and polar 494 K. YAMAGUCHI et al. lipid composition and fatty acid composition. MATERIALS AND METHODSMicroorganisms. Botryococcus braunii strain Austin belonging to the A race was obtained from the Austin culture collection (University of Texas) and B. braunii strain Berkeley belonging to the B race was originally isolated to unialgal culture by Dr. Arthur M. Nonomura from lilyculturing tanks in the Department of Botany greenhouse of the University of California, Berkeley.4) Henceforth, they are referred to as the A and B strai...

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