Edmonston measles virus prevents increased cell surface expression of peptide-loaded major histocompatibility complex class II proteins in human peripheral monocytes

Gamma interferon (IFN-gamma) induces expression of the gene products of the major histocompatibility complex (MHC), whereas IFN-alpha/beta can interfere with or suppress class II protein expression. In separate studies, measles virus (MV) was reported to induce IFN-alpha/beta and to up-regulate MHC class II proteins. In an attempt to resolve this paradox, we examined the surface expression of MHC class I and class II proteins in MV-infected peripheral monocytes in the presence and absence of IFN-alpha/beta. Infection of purified monocytes with Edmonston B MV resulted in an apparent increase in cell surface expression of HLA-A, -B, and -C class I proteins, but it had no effect on the expression of HLA-DR class II proteins. MV-infected purified monocytes expressed IFN-alpha/beta, but no measurable IFN-gamma expression was detected in supernatant fluids. Class II protein expression could be enhanced by coculture of purified monocytes with uninfected peripheral blood mononuclear cell (PBMC) supernatant. MV infection of PBMCs also did not affect expression of class II proteins, but the expression of HLA-A, -B, and -C class I proteins was increased two- to threefold in most donor cells. A direct role for IFN-alpha/beta suppression of MHC class II protein expression was not evident in monocytes since MV suppressed class II protein expression in the absence of IFN-alpha/beta. Taken together, these data suggest that MV interferes with the expression of peptide-loaded class II complexes, an effect that may potentially alter CD4(+)-T-cell proliferation and the cell-mediated immune responses that they help to regulate.     

Oral tool use by captive orangutans (Pongo pygmaeus)

Eight captive orangutans (Pongo pygmaeus) were given wooden blocks embedded with raisins and bamboo as raw material for tool making in a study of manual laterality. In about three quarters of the raisin extraction bouts, the orangutans held the tool in the lips or teeth rather than in their hands. Three adult males and 2 adult females showed extreme (> or =92%) preference for oral tool use, a subadult male and an adult female used oral tools about half the time, and 1 adult female preferred manual tool use. Most oral tool users made short tools (approx. 4-10 cm long) that were held in the lips and (probably) supported by the tongue. Preference for oral tool use does not correlate with body weight, age or sex, but it may be related to hand size or individual preference. This is the first report of customary oral tool use as the norm in captive orangutans; it resembles the behavioral patterns reported by van Schaik et al. and Fox et al. in nature.     

Human handedness: an ethological perspective

Human handedness is thought to be unique and universal. Critical examination of primary sources challenges both of these conclusions. Data on laterality of function in apes, humankind’s closest living relations, indicates hand preference and task specialization, but not yet handedness, as crucial studies remain to be done. Ethnographic data across cultures reveal more variance than is usually acknowledged, but existing findings are based on minimal and limited data. Ethological studies of spontaneous behavior in every day life are needed for both human and non-human primates.     

Are behavioral differences among wild chimpanzee communities genetic or cultural? An assessment using tool‐use data and phylogenetic methods

Over the last 30 years it has become increasingly apparent that there are many behavioral differences among wild communities of Pan troglodytes. Some researchers argue these differences are a consequence of the behaviors being socially learned, and thus may be considered cultural. Others contend that the available evidence is too weak to discount the alternative possibility that the behaviors are genetically determined. Previous phylogenetic analyses of chimpanzee behavior have not supported the predictions of the genetic hypothesis. However, the results of these studies are potentially problematic because the behavioral sample employed did not include communities from central Africa. Here, we present the results of a study designed to address this shortcoming. We carried out cladistic analyses of presence/absence data pertaining to 19 tool‐use behaviors in 10 different P. troglodytes communities plus an outgroup (P. paniscus). Genetic data indicate that chimpanzee communities in West Africa are well differentiated from those in eastern and central Africa, while the latter are not reciprocally monophyletic. Thus, we predicted that if the genetic hypothesis is correct, the tool‐use data should mirror the genetic data in terms of structure. The three measures of phylogenetic structure we employed (the Retention Index, the bootstrap, and the Permutation Tail Probability Test) did not support the genetic hypothesis. They were all lower when all 10 communities were included than when the three western African communities are excluded. Hence, our study refutes the genetic hypothesis and provides further evidence that patterns of behavior in chimpanzees are the product of social learning and therefore meet the main condition for culture. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Prospects for Bonobo Insectivory: Lui Kotal, Democratic Republic of Congo

Chimpanzees (Pan troglodytes) are well-known to eat invertebrates, especially social insects, across Africa, but allopatric bonobos (P. paniscus) are not. Bonobo insectivory is sparsely documented and apparently sporadic. However, the availability to bonobos of social insect prey and raw materials with which to make tools to exploit them is unknown. Here, we test a set of hypotheses that relates to questions of presence, abundance, density, and distribution of taxa that Pan consume and of vegetation suitable for making extractive foraging tools. We worked at Lui Kotal, Democratic Republic of Congo, where unprovisioned bonobos live in intact forest, far from villages. We collected insect and fecal specimens, transected for prey and assessed raw materials, and monitored mounds of Macrotermes. All but 1 of the major taxa of relevant termites, ants, and (stinging) honey bees were present. The 3 main taxa of insects that chimpanzees elsewhere eat —Macrotermes (fungus-growing termites), Dorylus (Anomma; army or driver ants), and Apis (honey bees)— were abundant and widespread, and usually at densities exceeding those at well-known chimpanzee study-sites. Similarly, woody and nonwoody vegetation suitable for making fishing probes was common at mounds of Macrotermes. There is no obvious ecological reason why bonobos should not use elementary technology in extractive foraging, e.g., termite-fish, ant-fish, ant-dip, honey-dip, to obtain social insects.     

Ant fishing by wild chimpanzees is not lateralised

Right-dominant handedness is unique and universal in Homo sapiens, suggesting that it is a highly derived trait. Our nearest living relations, chimpanzees, show lateralised hand preference when using tools, but not when otherwise manipulating objects. We report the first contrary data, that is, non-lateralised tool-use, for ant fishing as done in the Mahale Mountains of Tanzania. Unlike nut cracking, termite fishing, and fruit pounding, as seen elsewhere, in which most individuals are either significantly or wholly left- or right-biassed, ant fishers are mostly ambilateral. The clue to this exception lies in arboreality; all other patterns of chimpanzee elementary technology are done on the ground. Arboreal tool use usually requires not only that one hand be used to hold the tool, but also that the other hand gives postural support. When the supporting hand is fatigued, then it must be relieved by the other. Terrestrial tool use entails no such trading off. To test the hypothesis, we compared frequency of hand changing with the incidence of major hand support, and found them to be significantly positively correlated. The evolutionary transition from arboreality to terrestriality may have been a key enabler for the origins of human laterality.     

The human Rad51 K133A mutant is functional for DNA double-strand break repair in human cells

The human Rad51 protein requires ATP for the catalysis of DNA strand exchange, as do all Rad51 and RecA-like recombinases. However, understanding the specific mechanistic requirements for ATP binding and hydrolysis has been complicated by the fact that ATP appears to have distinctly different effects on the functional properties of human Rad51 versus yeast Rad51 and bacterial RecA. Here we use RNAi methods to test the function of two ATP binding site mutants, K133R and K133A, in human cells. Unexpectedly, we find that the K133A mutant is functional for repair of DNA double-strand breaks when endogenous Rad51 is depleted. We also find that the K133A protein maintains wild-type-like DNA binding activity and interactions with Brca2 and Xrcc3, properties that undoubtedly promote its DNA repair capability in the cell-based assay used here. Although a Lys to Ala substitution in the Walker A motif is commonly assumed to prevent ATP binding, we show that the K133A protein binds ATP, but with an affinity approximately 100-fold lower than that of wild-type Rad51. Our data suggest that ATP binding and release without hydrolysis by the K133A protein act as a mechanistic surrogate in a catalytic process that applies to all RecA-like recombinases. ATP binding promotes assembly and stabilization of a catalytically active nucleoprotein filament, while ATP hydrolysis promotes filament disassembly and release from DNA.