E ver-increasing interest is being directed to the role of innate processes in the immune system (1). Particular attention has been given recently to the group of genes that includes the natural killer cell (NK) receptors that are encoded at the leukocyte receptor cluster (LRC) locus on human chromosome 19q13.4 and similar receptors on mouse chromosome 7. These genes, which include killer Ig-like receptors (KIR), paired Ig-like receptors, Ig-like transcripts (ILT) [leukocyte inhibitory receptors (LIR) and monocyte inhibitory receptors (MIR)], leukocyte-associated inhibitory receptor genes, and NKp46͞MAR-1 (2-8), constitute a subset of the Ig gene superfamily (IgSF), and at least some members mediate innate recognition (9). The present understanding of LRC genes is based on studies in mammals; however, it is presumed that they arose early in vertebrate phylogeny.On the basis of considerations of both structural specialization and genetic complexity, it is possible that the Ig and T cell antigen receptor (TCR) multigene families, which undergo segmental reorganization and mediate adaptive immunity, arose from innate immune precursor receptors that are not associated with somatic reorganization. The ability of the Ig and TCR subset of the IgSF to recognize a multitude of antigens relies on extensive diversity in their variable (V) regions and is achieved through site-specific rearrangement of V, diversity (D), and joining (J) segmental elements as well as through additional somatic variation and ultimately somatic hypermutation. Within the V region, diversity in both families of antigen receptors is concentrated in complementarity determining regions (CDRs); variation in CDR1 and CDR2 is encoded in the germ line, whereas variation in CDR3 originates somatically. No evidence has been found for structural features or somatic reorganization associated with V regions in known members of the LRC.A third family of diversified V region-containing receptors, termed novel immune-type receptor (NITR) genes, was identified recently in the compact genome of the pufferfish (10). V regions of NITR genes in this species are organized in families, exhibit variation in CDR1 and CDR2, and like Ig and TCR genes encode J regions but neither rearrange nor appear to exhibit other forms of somatic variation (11). In an overall sense, NITRs are structurally similar to certain members of the LRC in that they possess two extracellular Ig domains, a transmembrane region and a cytoplasmic tail, which contains immunoreceptor tyrosine-based inhibition motifs (ITIMs) that function in negative signal transduction pathways. NITRs possess features of both adaptive and innate immune receptors, and their consideration is significant in addressing the evolution of immune function (12).Despite the utility of the pufferfish genome in terms of the initial identification of NITR genes, this model system is limited in terms of further defining the genetics, developmental regulation, cell lineage-specific expression, and function of NITRs. To address these ...
Social roles create conflicting behavioral expectations for female negotiators; however, virtual negotiations reduce social pressures. This paper reviews theoretical explanations on why men and women might differ in negotiations that occur through email, telephone, or video. Forty-three negotiation studies comparing face-to-face and virtual negotiations were examined for gender differences. All studies were reported in English but not limited to US participants. While many reports omitted gender information, meta-analytic findings supported the prediction that women would be more hostile in virtual compared to face-to-face negotiations, as well as finding no hostility difference for men between virtual and face-to-face negotiations. While negotiators overall were more successful face-to-face than virtually, results separated by gender did not find this effect.
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