STAGE-SPECIFIC EXPRESSION OF A MOUSE HOMOLOG OF THE PORCINE 135KDA ALPHA-D-MANNOSIDASE (MAN2B2) IN TYPE-A SPERMATOGONIA

The cDNA encoding a mouse homologue of porcine epididymis-specific 135 kDa alpha-D-mannosidase (MAN2B2, D28521) was cloned from the mouse te stis cDNA Library. It was found that 1018 amino acids were coded in it s open reading frame, and 62% of the amino acid sequence was identical to that of porcine MAN2B2. In the adult mouse, testis contained highe r amounts of mRNA encoding the MAN2B2 homologue than the epididymis, t hough porcine MAN2B2 was mainly expressed in the narrow region between the caput and corpus epididymis. mRNA of the mouse MAN2B2 homologue w as localized exclusively in spermatogonia in the testis. It was specif ically expressed in type A spermatogonia at stages IX similar to XI of spermatogenesis and was detected there until the cell developed into type B spermatogonia. We conclude that the expression of the MAN2B2 ho mologue can serve as a good marker for the late stages of type A sperm atogonia and may have an important role to play in the early step of s permatogenesis in mice. (C) 1997 Academic Press.