Growth factor independence-1 (GFI1) and GFI1B are closely related, yet differentially expressed transcriptional repressors with nearly identical DNA binding domains. GFI1 is upregulated in the earliest thymocyte precursors, while GFI1B expression is restricted to T lymphopoiesis stages coincident with activation. Transgenic expression of GFI1 potentiates T-cell activation, while forced GFI1B expression decreases activation. Both mice and humans with mutant Gfi1 display lymphoid abnormalities. Here we describe autoregulation of Gfi1 in primary mouse thymocytes and a human T-cell line. GFI1 binding to cis-element sequences conserved between rat, mouse and human Gfi1 mediates direct and potent transcriptional repression. In addition, dramatic regulation of Gfi1 can also be mediated by GFI1B. These data provide the first example of a gene directly targeted by GFI1 and GFI1B. Moreover, they support a role for auto- and trans-regulation of Gfi1 by GFI1 and GFI1B in maintaining the normal expression patterns of Gfi1, and suggest that GFI1B may indirectly affect T-cell activation through repression of Gfi1.

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This work presents the measurements made to define the temperature−composition curves for a set of binary systems composed of several pyridinium-based ionic liquids (ILs) [bpy][BF 4 ] and [bYmpy][BF 4 ] (Y = 2,3,4) with mono-and dihaloalkanes (Cl and Br) in the temperature interval [280−473] K and at atmospheric pressure. With the exception of the short chain dichloroalkanes (1,1-and 1,2-), all the compounds present some degree of immiscibility with the ionic liquids selected. Solubility points (x IL ,T) are determined by an image identification experimental procedure, which is described in detail and permits a more accurate definition of the liquid−liquid equilibria coexistence curves. A semiempirical model is proposed to correlate the experimental results of liquid−liquid equilibria (LLE) and the fits are compared with those obtained with the NRTL model. In both cases, a rigorous procedure is proposed to estimate LLE data considering the isoactivity criteria and a global test to guarantee the stability of the phases of the systems studied. H 1 −NMR spectra are determined for some of the systems chosen to study the molecular interactions and their influence on the experimental results.

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