Aim:To identify genes related to the human testis development by substrate hybridization technique.Methods:Ahuman testis cDNA microarray was constructed and hybridized with probes prepared from human adult and fetaltestes and spermatozoa mRNAs by reverse transcription reactions.The differentially expressed genes were sequenced.And a newly identified cullin-3 (CUL-3) transcript variant (designated cul-3b) was bio-informatically analyzed with anonline GenBank database.Multi-tissue reverse transcription polymerase chain reaction (RT-PCR) was used to deter-mine the tissue expression profile of cul-3b.Results:Cul-3b,a novel CUL-3 transcript variant,was identified.Theexpression level of cul-3b in adult testes was 3.79-fold higher than that in fetal ones.Cul-3b differed from cul-3(including NM_003590 and AY337761) in the opening reading frame and had three internal ribosomal entry sites(IRESes) in the 5’-UTR.These led to a 24 amino acid (aa) truncation at N-terminus of CUL-3b as compared withCUL-3 and a more motivated expression pattern of cul-3b under some strict circumstances.Additionally,cul-3bexpressed ubiquitously in human tissues according to multi-tissue RT-PCR.Conclusion:Cul-3b is a novel transcriptvariant of CUL-3,which may be important not only for the development of human testis but also for that of otherorgans. Aim: To identify genes related to the human testis development by substrate hybridization technique. Methods: Ahuman testis cDNA microarray was constructed and hybridized with probes prepared from human adult and fetaltes and spermatozoa mRNAs by reverse transcription reactions. The differentially expressed genes were sequenced. And a newly identified cullin-3 (CUL-3) transcript variant (designated cul-3b) was bio-informatically analyzed with an online GenBank database. Multi-tissue reverse transcription polymerase chain reaction expression profile of cul-3b. Results: Cul-3b, a novel CUL-3 transcript variant, was identified. The expression level of cul-3b in adult testes was 3.79-fold higher than that in fetal ones. -3 (including NM_003590 and AY337761) in the opening reading frame and had three internal ribosomal entry sites (IRESes) in the 5’-UTR. These led to a 24 amino acid (aa) truncation at N-terminus of CUL-3b as compared with CUL-3 and a more motivated expression pattern of cul-3b under some strict conditions. Additionally, cul-3 bexpressed ubiquitously in human tissues according to multi-tissue RT-PCR. Conlusion: Cul-3b is a novel transcript variant of CUL- which may be important not only for the development of human testis but also for that of otherorgans.