Dynamics and genetics of a disease-driven species decline to near extinction: lessons for conservation.

Amphibian chytridiomycosis has caused precipitous declines in hundreds of species worldwide. By tracking mountain chicken (Leptodactylus fallax) populations before, during and after the emergence of chytridiomycosis, we quantified the real-time species level impacts of this disease. We report a range-wide species decline amongst the fastest ever recorded, with a loss of over 85% of the population in fewer than 18 months on Dominica and near extinction on Montserrat. Genetic diversity declined in the wild, but emergency measures to establish a captive assurance population captured a representative sample of genetic diversity from Montserrat. If the Convention on Biological Diversity's targets are to be met, it is important to evaluate the reasons why they appear consistently unattainable. The emergence of chytridiomycosis in the mountain chicken was predictable, but the decline could not be prevented. There is an urgent need to build mitigation capacity where amphibians are at risk from chytridiomycosis.

Corf, the Rev/Rex homologue of HTDV/HERV-K, encodes an arginine-rich nuclear localization signal that exerts a trans-dominant phenotype when mutated.

Regulation of nucleo-cytoplasmic export of viral transcripts by a viral protein (Rev/Rex) is a characteristic feature in the replication cycle of complex retroviruses. We recently reported that the endogenous retrovirus family HTDV/HERV-K encodes a protein, Corf, that is a cellular Counterpart of Rev/Rex function and thus a new component of nucleo-cytoplasmic pathways. In HTDV/HERV-K-expressing cells, Corf is localized within the nucleoli. Here we describe the nuclear localization signal (NLS) of the Corf protein. Mutations in the NLS lead to cytoplasmic accumulation of the mutated protein and abrogate Corf function in a trans-dominant way.

Functional analysis of the env open reading frame in human endogenous retrovirus IDDMK(1,2)22 encoding superantigen activity.

Mice harbor a family of endogenous retroviruses, the mouse mammary tumor viruses (MMTV), which encode superantigens. These superantigens are responsible for the deletion of T cells expressing certain Vbeta chains of the T-cell receptor in the thymus. Human T cells are able to recognize MMTV-encoded superantigens presented by human major histocompatibility complex class II-positive cells. Owing to this and to the similarity of the human and murine immune systems, it was speculated that human endogenous retroviruses might also code for superantigens. Recently, it was reported that a proviral clone (IDDMK(1,2)22) of the human endogenous retrovirus family HTDV/HERV-K encodes a superantigen. The putative superantigen gene was located within the env region of the virus. Stimulated by these findings, we amplified by PCR and cloned into eucaryotic expression vectors open reading frames (ORFs) which were identical or very similar to IDDMK(1,2)22. When we transfected these vectors into A20 cells, a murine B-cell lymphoma, we were able to demonstrate mRNA expression and protein production. However, we did not find any evidence that the ORF stimulated human or murine T cells in a Vbeta-specific fashion, the most prominent feature of superantigens.

cORF and RcRE, the Rev/Rex and RRE/RxRE homologues of the human endogenous retrovirus family HTDV/HERV-K.

cORF, a protein encoded by the human endogenous retrovirus family HTDV/HERV-K, contains amino acid motifs which resemble the nuclear import and export signals of the viral regulatory proteins Rev (human immunodeficiency virus) and Rex (human T-cell leukemia virus [HTLV]). In this study, we demonstrated that cORF indeed has a Rev-like function and mapped the cORF-responsive RNA element to a sequence in the 3' long terminal repeat, a localization similar to RxRE, the responsive element in HTLV type 1. Accordingly, we have given the element the designation RcRE. cORF and RcRE stabilize unspliced and incompletely spliced viral transcripts and enhance their nuclear export via the CRM1 export pathway. So far, HTDV/HERV-K is the only endogenous retrovirus family with a complex regulation at the posttranscriptional level. It may be regarded as an intermediate in the evolution from simple to complex retroviruses.

In vivo blockade of the estradiol-binding-protein (EBP) by clomiphene citrate in human breast cancer.

PIP: The effect of clomiphene citrate given in vivo upon the in vitro uptake of labeled estradiol (tritiated-E2) was investigated in a 60-year-old patient with breast cancer who had had a mastectomy 10 months earlier followed by radiotherapy. Multiple subcutaneous metastatic nodules and enlargement of the liver were present but bone metastases could not be shown. A biopsy from a subcutaneous nodule, taken prior to present treatment, showed 86 fmol estradiol binding sites per mg of cytoplasmic protein with a dissociation constant of the estradiol-estradiol binding protein interaction of 2.8 X 10 -10 M. The patient was treated with 200 mg clomiphene citrate daily. Subjective symptoms improved and a reduction of skin nodule size and of liver enlargement followed. The serum enzymes alkaline phosphatase, nucleotidase, and phosphohexoseisomerase were diminished. A 2nd biopsy taken at Day 26 of treatment with clomiphene citrate showed complete inhibition of labeled estradiol tritiated-E2 uptake by the cytosol protein. This finding is thought to show the absence of free binding sites after clomiphene citrate therapy. Microscopic studies of biopsy material were unchanged. These results are thought to be the first to record human in vivo inhibition of trititated-E2 uptake for EBP by an antiestrogen compound, although similar in vitro observations have been made in human tumor specimens. There is thought to be a potential value of antiestrogenic agents, alone or with inhibitors of prolactin secretion, to replace endocrine ablations and to predict the response to endocrine therapy.^ieng