The breeding success and post-fledging survival of Choughs has been investigated on the island of Islay, which holds one of the densest breeding concentrations of Choughs in the British Isles. There was no significant difference in average young production per nest between birds nesting in buildings and those at the more traditional cliff sites. The overall average number of young fledged per nest per year was 2.02, which is lower than has been reported in other areas, despite the comparatively large clutch size of Choughs on Islay. From observations of marked birds, we estimated survival to be at least 71% in the first year of life and 74% in the second year, much higher than previously published estimates.

When the human T-cell line A3.01 is infected with HTLV-III/LAV, the virus associated with the acquired immune deficiency syndrome (AIDS), most of the cells are killed. However, a small number of cells that lack the Leu-3 surface marker survive. Under normal conditions these surviving cells do not produce virus, nor can they be infected by the virus, but they can be induced to produce virus by treatment with 5-iodo-2'-deoxyuridine. This response can be induced for as long as 3 months after the initial infection, suggesting that the cells may harbor a latent form of HTLV-III/LAV.

Abstract Normal human peripheral blood lymphocytes were tested for their susceptibility to infection with retroviruses isolated from patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex. Of 10 normal individuals tested, lymphocytes from all subjects became infected and produced virus as detected by assay for Mg+2-dependent reverse transcriptase. Lymphocytes from different individuals were demonstrated to be either high or low producers of reverse transcriptase after infection. The kinetics of virus production were similar in cells from both high- and low-producing individuals. A significant correlation was observed between high and low viral-producing lymphocytes and expression of the Leu-3/T4 (CD4) surface molecule. Mitogen-stimulated peripheral blood lymphocytes exposed to HTLV-III/LAV manifested productive viral infection, as reflected by the appearance of early syncytia, followed by reverse transcriptase. Unstimulated peripheral blood lymphocyte cultures displayed late syncytia but no detectable reverse transcriptase upon exposure to virus. The addition of anti-human interferon-alpha did not appear to have an appreciable effect on viral production in normal peripheral blood lymphocytes exposed to the virus.

Leu-3- cells that survive infection with the acquired immune deficiency syndrome (AIDS) retrovirus can be induced with IUdR to express infectious virus. A cellular clone (8E5), isolated by limiting dilution of a mass culture of survivor cells, was found to contain a single, integrated provirus that was constitutively expressed. Although IUdR treatment of 8E5 cells failed to induce infectious virus, cocultivation with Leu-3+ cells generated the characteristic syncytia associated with acute AIDS retrovirus infection. The single integrated copy of proviral DNA directs the synthesis of all major viral structural proteins except p64, as monitored by immunoblotting. The relationship of the 8E5 clone to viral latency and persistence is discussed.

Patients with the acquired immunodeficiency syndrome (AIDS) are subject to a spectrum of central nervous system (CNS) disorders. Recent evidence implicates the human T-cell lymphotropic virus type III (HTLV-III) in the pathogenesis of some of these illnesses, although, the cells infected by the virus have yet to be identified. Using in situ hybridization, we examined brain tissue from two patients with AIDS encephalopathy for the presence of HTLV-III RNA. In both cases, viral RNA was detected and concentrated in, though not limited to, the white matter. The CNS cells most frequently infected included macrophages, pleomorphic microglia, and multinucleated giant cells. Less frequently, cells morphologically consistent with astrocytes, oligodendroglia, and rarely neurons were also infected. The findings strengthen the association of HTLV-III with the pathogenesis of AIDS encephalopathy. In situ hybridization can be applied to routinely prepared biopsy tissue in the diagnosis of HTLV-III infection of the CNS.

The retrovirus frequently isolated from patients with the acquired immune deficiency syndrome (AIDS) has two novel open reading frames previously designated "A" and "B." The "A" region was found to be specifically expressed as polyadenylated RNA's of 5.5 and 5.0 kilobases in infected cells. The "B" region was expressed as 1.8- to 2.0-kilobase RNA species. Additional full-length and spliced messenger RNA's of the env region were also identified.

We have developed a continuous human T-cell line (A3.01) for the study of acquired immunodeficiency syndrome (AIDS)-associated retrovirus that mimics normal peripheral blood lymphocytes in susceptibility to viral cytopathic effect without the need for cell activation or conditioned medium. Following infection, substantial quantities of virus are produced during a 3- to 5-day period; the associated killing of cells can be monitored in a microtiter assay as a function of virus input. Southern blot hybridization of infected cellular DNAs indicated that no gross alteration occurred in the restriction maps of the proviral DNA during the transfer of virus to and its passage in A3.01 cells. This cell system offers an alternative to other AIDS retrovirus cell systems because it permits the monitoring of viral cytopathic effects.

In an analysis of the genomic variation of AIDS retroviral isolates from patients living in New York, Alabama, and Zaire, restriction maps were constructed by using seven enzymes, each known to cleave the proviral DNA more than once, in conjunction with Southern blot analysis. The maps of LAV, HTLV-III, and ARV-2 as deduced from their published nucleotide sequences were included in this analysis. The results demonstrated that (i) several "signature" restriction sites were common to all isolates; (ii) with the exception of LAV and HTLV-III, the North American and European isolates were all different from one another and showed no geographical specificity; (iii) the African isolates as a group were more diverse than those from North America and Europe; and (iv) the genomic variability was concentrated within the env gene.

The results of a study on the LEC growth of GaAs doped with Si, Ge, Sn, Se and Te are compared where appropriate with similar results on Bridgman, non-LEC, and epitaxial methods. The study involves distribution coefficient measurements and the effect of doping on mobility carrier concentration and compensation. The study on compensation has shown that Se and Tedoped LEC crystals have compensation ratios (NA/ND) typically ∼0.3 over a wide doping range in agreement with various studies on epitaxial GaAs. These results and those for Si and Ge doped LEC crystals which show values of compensation ratio of 0.4 and 0.8, respectively, are analysed using current physico-chemical and electrical models of compensation.