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Here, we report three attempts to replicate a finding from an influential psychological study (Griskevicius et al., 2011b). The original study found interactions between childhood SES and experimental mortality-priming condition in predicting risk acceptance and delay discounting outcomes. The original study used US student samples. We used British university students (replication 1) and British online samples (replications 2 and 3) with a modified version of the original priming material, which was tailored to make it more credible to a British audience. We did not replicate the interaction between childhood SES and mortality-priming condition in any of our three experiments. The only consistent trend of note was an interaction between sex and priming condition for delay discounting. We note that psychological priming effects are considered fragile and often fail to replicate. Our failure to replicate the original finding could be due to demographic differences in study participants, alterations made to the prime, or other study limitations. However, it is also possible that the previously reported interaction is not a robust or generalizable finding.

The first component of the human classical complement pathway is a Ca2 +-dependent protein complex containing two distinct functional units: Clq, the recognition subunit and Clr2-Cls2, the catalytic subunit, a CaZ+-dependent tetrameric association of two serine proteases, Clr and Cls (1). Binding of C1 (Clqr2s2) to immune complexes or aggregates containing IgG or IgM is mediated by Clq and leads to activation of the catalytic subunit by a two step process involving autolytic activation of proenzyme Clr to its activated form, and conversion of proenzyme Cls to its activated form which then cleaves the complement components C4 and C2. An antibody-independent route of complement activation (the lectin pathway) has been described which bypasses the use of the C1 complex. A serum lectin similar in shape and function to Clq, called MBL (mannose binding lectin) (2) also activates complement. MBL may act via via Clr and Cls but in vivo it is thought to act via 2 newly-described homologues of Clr and Cls, termed MASP-1 and MASP-2 (MBL-associated senne proteases) (3, 4). MBL binds to mannose/N-acetyl Dglucosamine-containing structures in bacteria, yeast and viruses through the C-type lectin domains (1). MASPs are novel serine proteases distinct from but similar to both Clr and Cls. The result of MASP activation is cleavage of C4 and C2, to form C4b2a. Unlike Clr or CIS, MASPs may act directly on C3, cleaving it at a low rate.(4). MBL and Clq consist of a modular structure that contains a N-terminal collagen-like triple helical region connected to a C-terminal globular 'head region. In Clq, Clr and Cls bind to the collagenous region.Clq circulates in plasma in the form of the 19s C1 complex. When this is dissociated in the presence of EDTA, Clq has a sedimentation coefficient of 11S, indicating that it is circulating in free, uncomplexed form. To determine if MBL circulates in a similar complex, sucrose density gradient centrifugation (SDG) of normal human serum was done. Serum was incubated in buffer either containing Ca2+ ions (10mM Tris-HCI, 65mM NaCl, 1mM CaC12, pH7.4) or EDTA (1OmM Tris-HCI, 65mM NaCl, 5mM EDTA, pH7.4) prior to centrifugation. Samples were centrifuged as described in the figure legend. .Seventeen fractions were cdlccted from each gradient and optical density (OD) readings at 280nm were measured (data not shown). Sedimentation coefficients for test samples were estimated by comparison of their mobility to those of standard proteins run simultaneously on a separate gradient under identical conditions. A standard curve was calculated by plotting radial distance (mm) against known sedimentation coefficients of the standards [bovine thyroglobulin (19.2s). bovine liver catalase (1 1.2S), bovine serum albumin (4.228) and equine skeletal muscle myoglobin (2.04S), taken from Smith ( 6 ) ] . Detection of MBL was with a direct enzyme linked immunosorbent assay (ELISA). Microtitre plates were prepared by coating each well with loop1 of each individual SDG fraction, diluted 1:4 in coating buffer (O.1M NaHCO-J, pH9....

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