Abstract: An optical connector having: a ferrule into which a first optical fiber is inserted; an optical fiber connector disposed at an back end of the ferrule; and a cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber. The end face on the back end side of the first optical fiber and an end face of a second optical fiber to be inserted into the optical fiber connector from a back end side thereof are to be connected by a butting connection. The cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

Abstract: It is intended to provide a host microorganism whereby the expression of a gene encoding a target protein can be effectively elevated in the case of transferring the gene. It is also intended to provide a transformant whereby a target protein can be produced at a high efficiency. It is further intended to provide a production process whereby a target protein can be produced at a high productivity. A microorganism which belongs to Eumycota and lacks the major isomaltose synthase. A gene encoding a target protein is transferred into the microorganism to give a transformant. Then the transformant is cultured under conditions allowing the expression of the transferred gene to thereby produce the protein.

Abstract: It is intended to provide a selection marker gene with the use of auxotrophy as an indication which is usable in transforming a fungus. Namely, a selection marker comprising a quinolinate phosphoribosyltransferase gene isolated from Aspergillus oryzae.

Abstract: It is intended to provide base sequences participating in the regulation of the expression of a promoter. It is also intended to modify a promoter based on the base sequence data to give a modified promoter having a high expression activity. Namely, a modified promoter constructed by inserting a first DNA fragment containing CCAATNNNNNN (a first base sequence) and a second DNA fragment containing CGGNNNNNNNNNGG (a second base sequence) into a promoter functioning in a filamentous fungus, wherein N in the base sequence denotes A (adenine), G (guanine), C(cytosine), or T (thymine).