CHO-K1 host cell engineering strategy enabling the establishment of strains producing higher yields of recycling antibodies

As described elsewhere (Biotechnol Bioeng 2010, 2013), our DXB11 (dhfr–) host cell engineering strategy achieved high cell viability for a prolonged period (more than 1 month) and enhanced mAb productivity (\u3e100 pg/cell/day) by nutritional control. Introduction of taurine transporter (TAUT) into DXB11 parent cells increased glutamine uptake and accelerated glutathione metabolism. By forcing the overexpression of TAUT, we were able to control DXB11 host cell functions and thereby increase the monoclonal antibody (mAb) titer up to 8.1 g/L/31 days under conventional 1-L bioreactor fed-batch conditions. Furthermore, the mAb produced by the DXB11/TAUT cells was comparable in quality to the mAb produced by the parent cells. In this study, we used CHO-K1 host cells and a chemically defined medium (CDM) for the development of cell lines producing recycling antibodies (rcAb). CDM adaptation and TAUT overexpression improved CHO-K1 cell performance. Rapid-growth CHO-K1/TAUT cells were developed, and these enabled the establishment of strains that produced higher yields of rcAb than did CHO-K1 parent cell (p \u3c 0.05). Viable cell density of these CHO-K1/TAUT/rcAb strains increased not only under shaker passage culture conditions (p \u3c 0.01) but also under shaker fed-batch culture conditions (p \u3c 0.01). These results suggest that our TAUT overexpression strategy also has a unique potential for the improvement of CHO-K1 host cells as well as DXB11 host cells

Millimeter-Thick Single-Walled Carbon Nanotube Forests: Hidden Role of Catalyst Support

A parametric study of so-called "super growth" of single-walled carbon nanotubes(SWNTs) was done by using combinatorial libraries of iron/aluminum oxide catalysts. Millimeter-thick forests of nanotubes grew within 10 min, and those grown by using catalysts with a thin Fe layer (about 0.5 nm) were SWNTs. Although nanotube forests grew under a wide range of reaction conditions such as gas composition and temperature, the window for SWNT was narrow. Fe catalysts rapidly grew nanotubes only when supported on aluminum oxide. Aluminum oxide, which is a well-known catalyst in hydrocarbon reforming, plays an essential role in enhancing the nanotube growth rates.Comment: 11 pages, 3 figures. Jpn. J. Appl. Phys. (Express Letters) in pres

Estimating Annual Available Amounts of Forest Biomass Resources with Total Revenues and Costs during the 60-Year Rotation in a Mountainous Region in Japan

This study extracted production forests and estimated the annual available amounts of forest biomass resources under profitable forest management. Production forests were extracted as sub-compartments where expected revenues surpassed all costs, from planting to final harvesting, for a 60-year rotation. These revenues and costs were estimated for two types of timber harvesting systems (a conventional operation system using a chainsaw and mini-forwarder, and a mechanized operation system using a processor and forwarder) and three types of forest biomass harvesting systems (normal extraction, landing sales, and no biomass extraction) in each sub-compartment using a geographic information system. Then, annual available amounts of forest biomass resources were estimated on the basis of annual supply potentials from production forests. The model was then applied to Nasushiobara City and the Kanuma area in Tochigi Prefecture, Japan. As a result, the number of profitable sub-compartments was estimated as 2,814 out of a total of 5,756 in Nasushiobara City, and 22,872 out of a total of 32,851 in the Kanuma area. The annual amounts of available forest biomass resources were estimated as 11,849 m3 y–1 and 115,213 m3 y–1 in Nasushiobara City and the Kanuma area, respectively. These amounts largely exceed the annual demands of a 500 kW woody biomass power generation plant planned in Nasushiobara City (6,000 m3 y–1) and a chip production factory located in the Kanuma area (12,000 m3 y–1), respectively. €1 = 143 yen on March 13, 201