[Intellectual contribution]

Production of high quality silks having different fluorescent colors by transgenic silkworms

Toshiki TAMURA1, Tetsuya IIZUKA1, Hideki SEZUTSU1, Ken-ichiro TATEMATSU1, Isao KOBAYASHI1, Masayuki YONEMURA1, Keiro UCHINO1, Katsura KOJIMA1, Hiroaki MACHII1, Chihiro TAKABAYASHI1, Katsushige YAMADA2, Hiroyuki KURIHARA2, Tetsuro ASAKURA3, Yasumoto NAKAZAWA3, Junji YAMAGUCHI4, Nobuo KUWABARA4, Takashi NAKAMURA5, Kei YOSHII5, Atsushi MIYAWAKI6, Satoshi KARASAWA7, Hatsumi KOBAYASHI7
1 Transgenic Silkworm Research Center, NIAS, 2 Toray Industries, Inc. 3 Tokyo University of Agriculture and Technology, 4 Gunma Sericultural Technology Center, 5 Textile Research Center of Gunma, 6 RIKEN, 7 Amalgaam, Ltd.
   Sericulture in Japan has declined over the past 20 years with reductions in is successively reduce the amounts of annual cocoon production and the numbers of the farmers rearing the silkworms during 20 years. Thise reduction has been is caused by the low prices of the cocoons and raw silk. To promote the sericulture Iin Japan, it was thought to be necessary to develop new silks and cocoons that couldcan sell for much higher prices. than those of the ordinal one. In addition, the new silks and the cocoons would be distinguished can be discriminated from the cocoons and silks available from made by the foreign countries such as, like China, Brazil, and India etc.
   National Institute of Agrobiological Sciences have recently developed the technology for making a transgenic silkworms and for the systems for the expressing of the transgenic. By using this technology, the artificially synthesized gene can be introduced into the silkworm and expressed in the silk gland. We applied the method for the production of high quality of recombinant silks, and found that the characteristics of the silk can be modified by introducing introduction of an artificial silk gene.
   In this topic, we report the production of large amounts of recombinant silk and attempts to produce higher quality fabrics using recombinant silks. We first generated transgenic silkworms that produce silks having interesting green, red or orange fluorescence characteristics (Fig. 1). To increase the production of fluorescent silk, these strains were back-crossed with the Japanese and Chinese parent races with selection in the successive generations. We generated the silkworms produced the high quality of the recombinant silks having different characters. The most interesting silk possesses the fluorescence of the green, red and orange color. We also developed a transgenic strain producing The very thin and strong silk by direct introduction of the artificial gene for thin silk into the thin silk race “Hachuring” . We then reared a large number of the silkworms and harvested a large amount of cocoons (Fig. 1). This is also turned out to be produced by the transgenic silkworm. The Silk with a cell-adhesive character is also was produced by the same method. In this topic we report the production of large amounts of recombinant silk and attempted to produce the higher quality of fabrics using the recombinant silks.
   We first generated the transgenic silkworms that produce the silks having the green, red and orange fluorescence or very thin fiber. The strains producing larger amount of the silks with the fluorescence were bred by back cross with Japanese and Chinese parent races and by the selection in the successive generations. The silkworm strain for the thin silk was performed by the direct introduction of the artificial gene for making the thin silk into the thin silk race. Then, we reared a large numbers of the silkworms and harvested large amounts of cocoons (Fig. 1).
   It was known that the fluorescence color of the silk was lost is loosed when the silk was reeled by the usual hot steam and water an ordinal method. We also investigated different the reeling methods using lower temperature so that of the cocoon without loosing the modified characters could be retained and as a result, we found that the drying and boiling of the cocoons at a lower temperature and the use of, a vacuum treatment and use of specific reagents were are required applicable for the reeling. As a result of this innovative, we innovated the technology, to reel the recombinant silk could be reeled and successfully to produce large amounts of silks retaining remained the fluorescence color (Fig. 1) as well as and the character of very thin fiber characteristic. Using these silks, we performed the production of the textile fabrics for (knit dresses, jackets and shawls) as shown in Fig. 2 and the interior accessories such as (lampshades and tapestries) as shown in Fig. 2.
   From these studies, results, we concluded that the production of high quality silks is possible using the newly developed to use the technology developed and that the recombinant silks produced by the transgenic silkworms may open the new fieled in Japanese sericulture and contribute to the increase in of the silk production.

Fig. 1 The cocoons and silk made from the transgenic silkworms introduced green (upper) or red (lower) fluorecence gene
Fig. 1  The cocoons and silk made from the transgenic silkworms introduced green (upper) or red (lower) fluorecence gene



Fig. 1 The cocoons and silk made from the transgenic silkworms introduced green (upper) or red (lower) fluorecence gene
Fig. 2  Woman’s wears made by the recombinant silk with the fluorescent colors


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