Zfyl is a mouse Y chromosomal gene encoding a zinc finger protein which is thought to have some function during spermatogenesis. Here we show that, when introduced into tissue culture cells, Zfyl is targeted to the nucleus. Two independent signals are present within the protein for nuclear localization. This nuclear Zfyl protein is able to bind strongly to DNA-ceHu-lose and, using site-selection assays, we have identified specific Zfyl DNA binding sites. Taken together these results suggest that Zfyl is a nuclear-located sequence-specific DNA binding protein which functions during spermatogenesis.

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As consumers start experimenting in cyberspace, the journalist's most urgent challenge is not the medium but the message. News organizations facing new competition and shrinking audiences need to reestablish the quality of their core product: reliable and useful information on which citizens can act.

Human immunoglobulin heavy chains are encoded by a highly complex locus, IGH, which encompasses many transcriptional units, including nine alternative constant region genes. Much of the constant region gene cluster was duplicated during hominoid evolution. In rodents, IGH is known to be regulated by multiple elements, including several enhancers 3' of the alpha chain-encoding A constant region gene, CA, the last transcribed region. Sequences downstream of the two human CA genes, possibly containing homologous enhancer elements, have not yet been reported. By long-range mapping of genomic DNA, a cluster of unmethylated rare restriction sites, representing a potential CpG island, was previously reported downstream of each CA gene, close to the 3' end of the duplicated region. Such potential CpG islands are candidates for additional IGH regulatory elements. We isolated bacteriophage clones containing these clusters of methylation-sensitive restriction sites, which lie within short CpG-rich stretches. Some of these sites showed tissue-specific methylation. 3' of the unmethylated CpG-rich sequences, clones derived from the 5' (telomeric) copy of the duplicated region, contained, in order, endogenous retroviral sequences, a processed ELK1 pseudogene, and the pseudogene IGHGP. Comparison with the presumed 3' (centromeric) copy of the duplicated region showed that similarity was lost exactly at the end of the retroviral long terminal repeat sequences. These results imply that an endogenous retroviral integration was present immediately 3' of IGH in the common hominoid ancestor and suggest models for the duplication of the region.

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