Temporal and tissue-specific expression of distinct retrovirus-like (VL30) elements during mouse development.

We have analyzed the expression of VL30 retroviral RNA transcripts during mouse embryogenesis. VL30 RNA was found in all tissues examined from mid-gestation, but increased dramatically at later times in the extraembryonic amnion and visceral yolk sac, and to a lesser extent in embryonic liver. The overall temporal and tissue-specific pattern of expression was unlike that of other retrotransposon gene families. S1 nuclease mapping experiments which distinguish transcripts from distinct VL30 elements suggest that they are independently regulated in different tissues during mouse development.