No abstract

Human T-lymphotropic virus type 1 (HTLV-1) is a suspected causative agent of adult T-cell leukemia. One of the viral genes encodes a protein (tat) that not only results in transactivation of viral gene expression but may also regulate the expression of certain cellular genes that are important for cell growth. Transgenic mice that expressed the authentic tat protein under the control of the HTLV-1 long terminal repeat were generated, and cell types that are permissive for the viral promoter and the effects of the tat gene on these cells were studied. Three of eight founder mice with high levels of expression of the transgene in muscle were bred and then analyzed. All developed soft tissue tumors at multiple sites between 13 to 17 weeks of age. This phenotype was transmitted to nine of nine offspring that inherited the tat gene and were available for analysis. The remaining five founders expressed the transgene in the thymus, as well as in muscle. This second group of mice all exhibited extensive thymic depletion and growth retardation; in all of these mice, death occurred between 3 to 6 weeks of age before tumors became macroscopically visible. The tat gene under the control of the HTLV-1 regulatory region showed tissue-specific expression and the tat protein efficiently induced mesenchymal tumors. The data establish tat as an oncogenic protein and HTLV-1 as a transforming virus.

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Selection and adjustment of proper physical parameters enables rapid DNA transport, site selective concentration, and accelerated hybridization reactions to be carried out on active microelectronic arrays. These physical parameters include DC current, voltage, solution conductivity and buffer species. Generally, at any given current and voltage level, the transport or mobility of DNA is inversely proportional to electrolyte or buffer conductivity. However, only a subset of buffer species produce both rapid transport, site specific concentration and accelerated hybridization. These buffers include zwitterionic and low conductivity species such as: d- and l-histidine; 1- and 3-methylhistidines; carnosine; imidazole; pyridine; and collidine. In contrast, buffers such as glycine, beta-alanine and gamma-amino-butyric acid (GABA) produce rapid transport and site selective concentration but do not facilitate hybridization. Our results suggest that the ability of these buffers (histidine, etc.) to facilitate hybridization appears linked to their ability to provide electric field concentration of DNA; to buffer acidic conditions present at the anode; and in this process acquire a net positive charge which then shields or diminishes repulsion between the DNA strands, thus promoting hybridization.