Semenogelin II gene is replaced by a truncated LINE1 repeat in the cotton-top tamarin

The human seminal vesicles secrete two proteins, semenogelin I and semenoge lin II, at very high concentrations. It has previously been shown that the cotton-top tamarin (Sanguinus oedipus), a New World monkey, is lacking the semenogelin II gene. We have now determined the nucleotide sequence of DNA located 5-13 kilobases (kb) downstream of the tamarin semenogelin I gene-a region that in man is occupied by the semenogelin II gene. Two regions with homology to the human semenogelin II gene were identified in the tamarin D NA. The first region, of 3.5 kb, is homologous to DNA upstream of the human gene, and the second region, of 0.6 kb, is mainly derived from the second intron. Between these regions, equivalent to 594 base pairs (bp) upstream o f the transcription initiation site to 12 bp downstream of the stop codon i n the human semenogelin II gene, the cotton-top tamarin DNA carries a trunc ated LINE1 repeat. In another set of experiments, the tamarin DNA hybridizi ng to the mouse semenoclotin gene was investigated. It was concluded that h ybridization is with the second intron of the semenoclotin gene, but very l ikely, the material does not represent a cotton-top tamarin semenoclotin ge ne. Thus, a mammalian ancestor probably carried a single gene that in the r odent lineage developed into the semenoclotin gene and in the primate linea ge into a progenitor of the semenogelin genes.