Abstract: Killifish genes which are expressed specifically to females in accordance with the phenotype sex, characterized by having a base sequence selected from among the base sequences represented by SEQ ID NOS: 1 to 21 in Sequence Listing.

Abstract: In a mass storage system, a method for controlling the stepping feed of an information medium (T) on which recording tracks are formed by stripes (T.sub.n) which run diagonally or vertically across the information medium is disclosed. According to this method, the feed of the information medium (T) begins after the completion of the recording or reading operation of data (DATA) upon a first recording track (T.sub.n) and prior to the completion of the checking of the content of the data (DATA). After that, it is determined whether the feed of the information medium is continued or reversed should be in accordance with the result of checking the content of the data (DATA). That is, when no error is detected as a result of the checking, the feed is continued so as to perform the recording or reading operation of data (DATA') upon a second recording track (T.sub.n+1).