Transmission of multiple traditions within and between chimpanzee groups

Field reports provide increasing evidence for local behavioral traditions among fish, birds, and mammals. These findings are significant for evolutionary biology because social learning affords faster adaptation than genetic change and has generated new (cultural) forms of evolution. Orangutan and chimpanzee field studies suggest that like humans, these apes are distinctive among animals in each exhibiting over 30 local traditions. However, direct evidence is lacking in apes and, with the exception of vocal dialects, in animals generally for the intergroup transmission that would allow innovations to spread widely and become evolutionarily significant phenomena. Here, we provide robust experimental evidence that alternative foraging techniques seeded in different groups of chimpanzees spread differentially not only within groups but serially across two further groups with substantial fidelity. Combining these results with those from recent social-diffusion studies in two larger groups offers the first experimental evidence that a nonhuman species can sustain unique local cultures, each constituted by multiple traditions. The convergence of these results with those from the wild implies a richness in chimpanzees' capacity for culture, a richness that parsimony suggests was shared with our common ancestor.     

Control, choice, and assessments of the value of behavioral management to nonhuman primates in captivity

Many people have devoted considerable effort to enhancing the environments of nonhuman primates in captivity. There is substantial motivation to develop experimental, analytical, and interpretational frameworks to enable objective measurements of the value of environmental enrichment/behavioral management efforts. The consumer-demand approach is a framework not frequently implemented in studies of nonhuman primate welfare but profitably used in studies of the welfare of nonhuman animals in agriculture. Preference studies, in which primates can voluntarily choose to socialize or to participate in training, may be the best current examples of a consumer-demand-like approach to assessing the effects of captive management strategies on primate welfare. Additional work in this area would be beneficial; however, there are potential ethical constraints on purposefully subjecting primates to adverse circumstances to measure their demand for a resource. Primate welfare researchers need to design consumer-demand studies with obstacles that will help measure the relative value of resources to captive primates without compromising the welfare they are attempting to evaluate and enhance.     

Identification of adult mouse neurovirulence determinants of the Sindbis virus strain AR86

Sindbis virus infection of mice has provided valuable insight into viral and host factors that contribute to virus-induced neurologic disease. In an effort to further define the viral genetic elements that contribute to adult mouse neurovirulence, the neurovirulent Sindbis virus strain AR86 was compared to the closely related (22 single amino acid coding changes and the presence or absence of an 18-amino-acid sequence in nsP3 [positions 386 to 403]) but avirulent Girdwood strain. Initial studies using chimeric viruses demonstrated that genetic elements within the nonstructural and structural coding regions contributed to AR86 neurovirulence. Detailed mapping studies identified three major determinants in the nonstructural region, at nsP1 538 (Ile to Thr; avirulent to virulent), an 18-amino-acid deletion in nsP3 (positions 386 to 403), and nsP3 537 (opal to Cys; avirulent to virulent), as well as a single determinant in the structural genes at E2 243 (Leu to Ser; avirulent to virulent), which were essential for AR86 adult mouse neurovirulence. Replacing these codons in AR86 with those found in Girdwood resulted in the attenuation of AR86, while the four corresponding AR86 changes in the Girdwood genetic background increased virulence to the level of wild-type AR86. The attenuating mutations did not adversely affect viral replication in vitro, and the attenuated viruses established infection in the brain and spinal cord as efficiently as the virulent viruses. However, the virus containing the four virulence determinants grew to higher levels in the spinal cord at late times postinfection, suggesting that the virus containing the four attenuating determinants either failed to spread or was cleared more efficiently than the wild-type virus.     

Phorbol myristate acetate (PMA) augments chemoattractant-induced diglyceride generation in human neutrophils but inhibits phosphoinositide hydrolysis. Implications for the mechanism of PMA priming of the respiratory burst

Pretreatment ("priming") of neutrophils with a non-activating concentration (2 nM) of phorbol myristate acetate (PMA) augments superoxide (O2-) production in response to the chemoattractant formylmethionylleucylphenylalanine (fMLP). We initially examined the effect of sphinganine, an inhibitor of protein kinase C (Ca2+/phospholipid-dependent enzyme), on activation of primed neutrophils. In both primed and unprimed cells activation by fMLP was blocked, and inhibition occurred at identical concentrations, supporting a common inhibited site. PMA also augmented (about 2-fold) fMLP-induced generation of sn-1,2-diglyceride (DG), the level of which correlated with O2- generation. In contrast to its effects on DG, PMA diminished by about 50% the magnitude of the fMLP-stimulated rise in cytosolic Ca2+. Thus, PMA priming dissociates the fMLP-stimulated Ca2+ increase from DG and O2- generation. The effect of PMA on Ca2+ levels appeared to be due in part to lowered levels of inositol trisphosphate. Lowering of inositol phosphate levels correlated with inhibition of fMLP-induced hydrolysis of inositol-containing phospholipids, particularly phosphatidylinositol 4,5-bisphosphate. PMA did not inhibit (and in fact augmented at early time points) formation of [32P] phosphatidic acid in response to fMLP, indicating that the increase in DG was not due to inhibition of cellular diglyceride kinase. Thus, the data suggest that PMA enhances fMLP-stimulated DG generation concomitant with switching the source of DG from phosphatidylinositol 4,5-bisphosphate to an alternative lipid(s). Increased DG and inhibition of activation by sphinganine are consistent with a role for protein kinase C in activation of the respiratory burst in PMA-primed neutrophils.     

Stimulation of adrenal mitochondrial cholesterol side-chain cleavage by GTP, steroidogenesis activator polypeptide (SAP), and sterol carrier protein2. GTP and SAP act synergistically

Several factors are known to stimulate cholesterol side-chain cleavage in isolated adrenal mitochondria, including steroidogenesis activator polypeptide (SAP), GTP, and sterol carrier protein2 (SCP2). All of these reportedly function at the level of the translocation of cholesterol to the inner membrane wherein side-chain cleavage to form pregnenolone occurs. We have investigated the activating effects of these factors alone and in combination. Under conditions where exogenous cholesterol is provided and multiple turnovers of a transport system are required, GTP stimulated steroidogenesis in isolated mitochondria and in adrenal homogenates, and this effect was enhanced by a GTP regenerating system. SAP alone had little effect under these conditions, but synergized with GTP to stimulate cholesterol metabolism. A truncated SAP analog and a variant from the C terminus of the minor heat-shock protein GRP78 had similar effects, but an unrelated peptide had no effect. GTP stimulated side-chain cleavage with the same EC50 in both resting mitochondria (from dexamethasone-treated rats) and in activated mitochondria (from ether-treated rats), but SAP effects were most apparent in resting mitochondria. In contrast, SCP2 stimulation was additive with other factors, suggesting an independent mechanism of action. While the data are consistent with biological roles for these factors, the relatively small magnitude of the in vitro effects may indicate that cell disruption and mitochondrial isolation disrupt important structural or other features which are necessary for the full expression of the steroidogenic response.     

Evolution and the expression of biases: situational value changes the endowment effect in chimpanzees

Cognitive and behavioral biases, which are widespread among humans, have recently been demonstrated in other primates, suggesting a common origin. Here we examine whether the expression of one shared bias, the endowment effect, varies as a function of context. We tested whether objects lacking inherent value elicited a stronger endowment effect (or preference for keeping the object) in a context in which the objects had immediate instrumental value for obtaining valuable resources (food). Chimpanzee subjects had opportunities to trade tools when food was not present, visible but unobtainable, and obtainable using the tools. We found that the endowment effect for these tools existed only when they were immediately useful, showing that the effect varies as a function of context-specific utility. Such context-specific variation suggests that the variation seen in some human biases may trace predictably to behaviors that evolved to maximize gains in specific circumstances.     

Observational learning in chimpanzees and children studied through 'ghost' conditions

Emulation has been distinguished from imitation as a form of observational learning because it focuses not on the model's actions but on the action's environmental results. Whether a species emulates, imitates or displays only simpler observational learning is expected to have profound implications for its capacity for cultural transmission. Chimpanzees' observational learning has been suggested to be primarily emulative, but this is an inference largely based upon low fidelity copying in experiments when comparing chimpanzees with humans rather than direct testing. Here we test directly for emulation learning by chimpanzees and children using a 'ghost' condition in which a sliding door obscuring a reward was moved to left or right with no agent visible, a context associated with the only published evidence for emulation learning in a non-human species (pigeons). Both children and chimpanzees matched the observed direction of ghost door movement on their first test trial. This is the first evidence for emulation in a non-human primate in the restricted context of a ghost condition. However, only the children continued to match in later trials. Individuals of both species continued to match with 99% or better fidelity when viewing a conspecific model operates the door. We conclude that chimpanzees can and will display emulation learning when the task is as simple as the present one, which contrasts with a failure to do so in a more complex manipulative task tested earlier. However, even with a simple task, emulation alone creates only fleeting fidelity compared with the opportunity to copy a conspecific, when considerable conformity is displayed.     

Murine cytokine responses following multiple oral immunizations using lipid-formulated mycobacterial antigens

Oral vaccination of mice with live Mycobacterium bovis BCG in lipid-formulation induces a gamma-interferon response that can be measured systemically, and confers protection against aerosolized mycobacterial challenge. Here, we have investigated cytokine responses following the vaccination, drawing comparisons between mice that received single or multiple oral immunizations and between mice receiving formulations containing live BCG or non-replicating mycobacterial antigens. Single oral immunization with lipid-formulated live BCG invoked secreted and cellular IFN-gamma responses in mice 8 weeks post-vaccination, the magnitudes of which were significantly elevated in mice receiving multiple immunizations over the 8-week period. Single oral immunization with live BCG also invoked an interleukin-2 response (but not TNF-alpha or IL-4), although the magnitude was not elevated by multiple immunizations. Multiple immunizations with lipid-formulated soluble or particulate non-replicating mycobacterial antigens failed to invoke cytokine responses, except for a low-level IFN-gamma response in mice multiple immunized with lipid-formulated heat-killed BCG. These results are discussed in contrast to the known patterns of cytokine induction following parenteral-route immunization with live or non-replicating mycobacterial antigens and with practical reference to the development of oral-delivery vaccines against tuberculosis.     

Diradylglycerol synergizes with an anionic amphiphile to activate superoxide generation and phosphorylation of p47phox in a cell-free system from human neutrophils

The superoxide-generating respiratory burst oxidase (NADPH oxidase) from human neutrophils can be activated in a cell-free system consisting of plasma membranes, cytosol, and an anionic amphiphile such as sodium dodecyl sulfate (SDS) or arachidonate, and guanosine 5'-(3-O-thio)triphosphate (GTP(gamma)S) augments activation. We report herein that short-chain diacylglycerols (e.g. dioctanoylglycerol (diC8)) synergize with SDS in the activation of superoxide generation in a dose- and time-dependent manner, resulting in rates up to 1400 nmol/min/mg plasma membrane protein, or 250-700% higher than the rate seen with SDS alone. diC8 did not affect significantly the dose response for either cytosol or SDS, indicating that the activation was not due to increased sensitivity of the oxidase toward either of these components. At optimal concentrations of SDS and diC8, additional activation was observed in the presence of GTP(gamma)S, indicating that diC8 and GTP activate by separate mechanisms. In contrast to diC8, other known activators of protein kinase C (phorbol myristate acetate and mezerein) augmented SDS activation only minimally (typically 20-30%), and neither diacylglycerols nor tumor promoters activated in the absence of SDS. Activation by diC8 was calcium and phosphatidylserine independent, and the specificity for neutral lipids was atypical for protein kinase C. Inhibitors of protein kinase C (staurosporine and a peptide substrate analog) also failed to inhibit the response. Nevertheless, phosphorylation of several neutrophil proteins including p47phox was seen with both SDS and diC8, and synergistic phosphorylation of p47phox was seen when both activating factors were present. Thus, diacylglycerol synergizes with SDS in activating both superoxide generation and p47phox phosphorylation in the cell-free activation system, but the activation is atypical of a protein kinase C mechanism.