Estrogen receptor beta and breast cancer.

A second estrogen receptor, estrogen receptor-beta, was identified in 1996 and has led to an intensive re-evaluation of the role of estrogens in normal physiological and disease processes. While much has been learnt about this new receptor, there remain many outstanding questions, particularly regarding its prognostic significance and therapeutic implications.

Human endogenous retrovirus expression and reverse transcriptase activity in the T47D mammary carcinoma cell line.

We have examined the human mammary tumor cell line T47D and have found that these cells produce virus-like particles which band at the typical density for retroviral particles on a sucrose gradient, possess reverse transcriptase activity, and package HERV-K10-like sequences. Using this information and a bacterial expression system to identify long open reading frames, we have identified individual clones which have full-length open reading frames for reverse transcriptase and RNase H and which could encode the reverse transcriptase activity detected in these cells.

The prevalence of latent Equid herpesviruses in the tissues of 40 abattoir horses.

Equid herpesviruses 1 or 4 (EHV-1 or -4) were isolated by cocultivation from 60% of 40 horses examined at slaughter. The lymph nodes draining the respiratory tract were the most common source of virus. EHV-1 or EHV-4 was never isolated from the trigeminal ganglia (SLG). The polymerase chain reaction (PCR) detected virus in 87.5% of bronchial lymph nodes and a similar level in the trigeminal ganglia that were examined. By both assays approximately one third of the positive animals harboured both viruses. Equid herpesvirus 2 (EHV-2) was isolated from all but one of the horses and from > 75% of the lymph nodes draining the respiratory tract; alpha viruses were isolated only in the presence of EHV-2. The results indicate that latent EHV-1 and EHV-4 are widespread in the equine population and that the primary site of latency is the lymph nodes of the respiratory tract.

Cross-hybridization of equid herpesvirus-2 (EHV-2) and herpes simplex virus-1 (HSV-1) genes to equid herpesvirus-1 (EHV-1).

In contrast to previous findings, the Ab4 isolate of equid herpesvirus-1 (EHV-1) was shown to share homology with the G9 isolate of equid herpesvirus-2 (EHV-2). Using Southern blotting and stringent hybridization conditions, a significant proportion of this cross-hybridization was identified by the immediate-early gene-3 (IE-3) probe from herpes simplex virus-1 (HSV-1). The HSV-1 UL48 gene probe (encoding the IE gene transactivating protein VmW65, which is also known as alpha-TIF or VP16) was used to identify and isolate its counterpart in EHV-1. The relevance of shared homology to transactivation is being investigated.

Latent equid herpesviruses 1 and 4: detection and distinction using the polymerase chain reaction and co-cultivation from lymphoid tissues.

The polymerase chain reaction (PCR) and co-cultivation were used to identify the lymphoreticular system as the site of latency of equid herpesvirus I (EHV-1). Primers for PCR were designed from aligned nucleotide sequences of the glycoprotein gB genes to amplify the same region of both the EHV-1 and EHV-4 genomes. Subsequent restriction digests using specific enzymes distinguished the amplified fragments of the EHV-1 genome from those of the EHV-4 genome. Ten weeks following an experimental infection of five ponies with EHV-1, latent virus was detected by PCR and recovered by co-cultivation, predominantly from lymphoid tissues draining the respiratory tract. Significantly, latent EHV-1 also persisted in peripheral blood leukocytes (PBL). Latent EHV-4, presumably from a preceding natural infection, was also detected in some tissues, including PBL, from all animals. Of additional interest was the recovery of EHV-1 and -4 only in the presence of the ubiquitous EHV-2.

Transposition, amplification, and divergence in the origin of the DNF15 loci, a polymorphic repetitive sequence family on chromosomes 1 and 3.

The loci DNF15S1 and DNF15S2 are members of a small repetitive sequence family at discrete chromosomal locations, namely, 1p36 and 3p21, respectively. Studies of the structure, arrangement, and interrelations of the family suggest that the single copy on chromosome 3 is the original member and that this gave rise to the several members on chromosome 1 by transposition, partial duplication, and amplification. Several restriction fragment length polymorphisms have been discovered at the DNF15S1 locus and these have been assigned to the different subfamilies of the repeat at this locus. The existence of these RFLPs, and the nonallelic restriction site variation also found in this sequence family, suggests that transposition and amplification occurred as discrete events. We sequenced across the ancient junction between chromosomes 1 and 3 and noted features which might explain the mechanics of the transposition and amplification events.

An alpha-fucosidase pseudogene on human chromosome 2.

In Chinese hamster-human hybrids with overlapping translocations, the major site of hybridization of a cDNA clone for the liver form of human alpha-L-fucosidase was 1p36.13----1p34, consistent with hybridization to the FUCAl locus. No hybridization to the FUCA2 locus on chromosome 6 was observed. Hybridization to a genomic sequence on chromosome 2 was, however, detected, thus defining a new FUCA-like locus. The restriction map of the alpha-fucosidase cDNA could be exactly superimposed upon its region of homology within a genomic clone containing this FUCA-like locus, suggesting that it is a processed pseudogene.

Sequences homologous to the human D1S1 locus present on human chromosome 3.

We have investigated the segregation, in somatic cell hybrids, of the human D1S1 locus, previously assigned to 1p36 by in situ hybridization. We have shown that the clone which defines this locus, lambda Ch4A-H3, originates from human chromosome 3, but contains a 1.7-kilobase (kb) PstI-HindIII repetitive element that is also present on chromosome 1, probably distal to PGD. The clone recognizes restriction fragment length polymorphisms within the single-copy sequence on chromosome 3 and one for the enzyme StuI in the repeated sequence on chromosome 1. These experiments thus expose a level of complexity in the D1S1 locus not revealed by earlier in situ hybridization studies.

Diverse origins of multiple ovarian teratomas in a single individual.

Centromere heteromorphisms and enzyme markers were examined in cells cultured from seven benign ovarian teratomas arising in a single patient. Three of the teratomas were homozygous for all eight enzyme and centromere markers found to be heterozygous in the host. The other four tumors were heterozygous at the centromeres of chromosomes 1, 16, 17, and 18, as in the patient, but were homozygous for at least one of the enzyme markers. The linkage phases of the heterozygous enzyme markers phosphogluconate dehydrogenase and phosphoglucomutase 1 and the chromosome 1 centromere heteromorphism were established for the patient and for three of the heterozygous teratomas by analysis of Chinese hamster-human somatic cell hybrids. The linkage phase of these markers in homozygous and heterozygous tumors was in every case different from that in the host. The finding of heterozygous centromeres in ovarian teratomas excludes suppression of meiosis II as a mechanism for their origin, and we suggest rather that they arise by failure of meiosis I. The linkage phases in the fully homozygous tumors are most readily derived from that in the patient, we suggest, by endoreduplication of a haploid gamete. The varied origin of ovarian teratomas has important implications for the suitability of such material for centromere-based gene mapping.