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PubMed2001

Architectonic identification of the core region in auditory cortex of macaques, chimpanzees, and humans.

The goal of the present study was to determine whether the architectonic criteria used to identify the core region in macaque monkeys (Macaca mulatta, M. nemestrina) could be used to identify a homologous region in chimpanzees (Pan troglodytes) and humans (Homo sapiens). Current models of auditory cortical organization in primates describe a centrally located core region containing two or three subdivisions including the primary auditory area (AI), a surrounding belt of cortex with perhaps seven divisions, and a lateral parabelt region comprised of at least two fields. In monkeys the core region can be identified on the basis of specific anatomical and physiological features. In this study, the core was identified from serial sets of adjacent sections processed for cytoarchitecture, myeloarchitecture, acetylcholinesterase, and cytochrome oxidase. Qualitative and quantitative criteria were used to identify the borders of the core region in individual sections. Serial reconstructions of each brain were made showing the location of the core with respect to gross anatomical landmarks. The position of the core with respect to major sulci and gyri in the superior temporal region varied most in the chimpanzee and human specimens. Although the architectonic appearance of the core areas did vary in certain respects across taxonomic groups, the numerous similarities made it possible to identify unambiguously a homologous cortical region in macaques, chimpanzees, and humans.

Acetylcholinesterase↗

PubMed2004

Associative learning and memory in a chimpanzee fetus: Learning and long-lasting memory before birth.

We tested whether a chimpanzee fetus could form an association between an extrauterine tone and vibroacoustic stimulation (VAS) using classical conditioning treatment. Two kinds of pure tone were used as the conditioned stimuli, one where a 500-Hz tone was always followed by a VAS of 80 Hz (110 gal), the unconditioned stimulus (US), and another where a 1000-Hz tone was never followed by a VAS. This treatment was repeated 156 times in total until natural labor at 233 days of gestational age. Behavioral tests on the 33rd and 58th days after birth revealed a differential response to the tones: The infant displayed an exaggerated response to the 500-Hz tone, but not to the 1000-Hz tone. Other naïve chimpanzee infants did not show any response to either tone, which suggests that a chimpanzee fetus can distinguish between tones and form an association, and that it retains such information for at least 2 months after birth.

Animals↗

PubMed1989

Conspecific screams and laughter: cardiac and behavioral reactions of infant chimpanzees.

The present study examined cardiac and behavioral reactions of infant chimpanzees to white noise and to conspecific screams and laughter. Chimpanzee screams evoked typical deceleratory cardiac orienting responses. Analysis of stimulus-evoked changes in respiratory sinus arrhythmia suggested that this cardiac deceleration arose from an increase in parasympathetic activity. In contrast, chimpanzee laughter evoked notable cardiac acceleration. Laughter also evoked vocalizations from the infant subjects, which were reminiscent of adult threat-barks. Analysis of respiratory sinus arrhythmia suggested that the cardioacceleratory response likely resulted from sympathetic activation, and was not associated with an inhibition of parasympathetic activity. The autonomic and vocal responses to laughter emerged early in development, were minimally dependent on social contact with adults, and declined in magnitude with increasing age. A consideration of the phylogeny of laughter raised the possibility that the functional reaction to this vocalization may be related to its origin in more primitive agonistic facio-vocal signals.

Animals↗

PubMed1993

Hemispheric specialization in infant chimpanzees (Pan troglodytes): evidence for a relation with gender and arousal.

The current study extends previous documentation of behavioral asymmetries in hand-to-mouth, self-consoling behaviors of infant chimpanzees. The underlying source of lateralized hand-to-mouth, self-calming behavior was investigated by comparing individual differences in neonatal arousal levels, regulatory ability, and motor performance with individual differences in the degree of laterality at 3 months. Asymmetrical hand-to-mouth, self-calming behaviors at 3 months of age were significantly related to general arousal at 2 days of age (i.e., the Range of State cluster scores measured by the Brazelton Neonatal Behavioral Assessment Scale). Simply stated, chimpanzees with a right-hand bias in hand-to-mouth behavior exhibited lower arousal at 2 days of age compared with nonright-handed individuals. The only item of the Range of State cluster to distinguish subjects was irritability: Right-handed subjects were less irritable. Previously, a trend was reported with respect to sex differences in the laterality of hand-to-mouth behavior. With the greater number of subjects in the present study, we found that females exhibited a significantly greater right-hand bias for hand-to-mouth behaviors (12 of 13) than did males (9 of 15). We conclude that neonatal arousability, and not regulatory capacity or motor performance, predicts the degree of laterality found in hand-to-mouth, self-calming behaviors in 3-month-old chimpanzees. These data are discussed from the standpoint of early pari-parturitional or intrauterine factors affecting lateralized development.

Animals↗

PubMed1994

Hand preferences for bimanual feeding in 140 captive chimpanzees (Pan troglodytes): rearing and ontogenetic determinants.

Hand preference in bimanual feeding was assessed in 140 captive chimpanzees (Pan troglodytes). Bimanual feeding was defined as the active use of one hand for feeding with the opposite hand holding other food items. In terms of strength of hand preference, adults were more lateralized than sub-adults. Additionally, mother-reared chimpanzees were more lateralized than nursery-reared chimpanzees. The number of subjects with no hand preference was more prevalent in sub-adults compared with young and older adults. Of those subjects with a significant hand preference, a larger proportion exhibited a right-hand preference. These results are discussed in relation to previous reports of handedness and bimanual feeding in gorillas and bonobos.

Aging↗

PubMedDate not supplied

Acute hepatitis A infection in hepatitis B chimpanzee carriers.

Two hepatitis B virus carrier chimpanzees which were superinfected with hepatitis A virus developed acute hepatitis followed by the production of antibodies to hepatitis A virus. The Southern blot technique employed to monitor liver hepatitis B virus DNA revealed that the amount of viral DNA in both animals was significantly reduced during the acute phase of hepatitis A infection. The levels of plasma hepatitis B DNA polymerase activity were also reduced in one chimpanzee. The high titers of HBsAg in the circulation remained unchanged throughout the study, and antibodies to the surface antigen and to e antigen were not detected. The morphological lesions in the liver were severe in one chimpanzee from whom one specimen showed both periportal focal necrosis and zonal parenchymal necrosis.

Animals↗

PubMed2007

Understanding the recent evolution of the human genome: insights from human-chimpanzee genome comparisons.

The sequencing of the chimpanzee genome and the comparison with its human counterpart have begun to reveal the spectrum of genetic changes that has accompanied human evolution. In addition to gross karyotypic rearrangements such as the fusion that formed human chromosome 2 and the human-specific pericentric inversions of chromosomes 1 and 18, there is considerable submicroscopic structural variation involving deletions, duplications, and inversions. Lineage-specific segmental duplications, detected by array comparative genomic hybridization and direct sequence comparison, have made a very significant contribution to this structural divergence, which is at least three-fold greater than that due to nucleotide substitutions. Since structural genomic changes may have given rise to irreversible functional differences between the diverging species, their detailed analysis could help to identify the biological processes that have accompanied speciation. To this end, interspecies comparisons have revealed numerous human-specific gains and losses of genes as well as changes in gene expression. The very considerable structural diversity (polymorphism) evident within both lineages has, however, hampered the analysis of the structural divergence between the human and chimpanzee genomes. The concomitant evaluation of genetic divergence and diversity at the nucleotide level has nevertheless served to identify many genes that have evolved under positive selection and may thus have been involved in the development of human lineage-specific traits. Genes that display signs of weak negative selection have also been identified and could represent candidate loci for complex genomic disorders. Here, we review recent progress in comparing the human and chimpanzee genomes and discuss how the differences detected have improved our understanding of the evolution of the human genome.

Animals↗

PubMed2002

In vitro susceptibility to infection with SIVcpz and HIV-1 is lower in chimpanzee than in human peripheral blood mononuclear cells.

This study was undertaken to evaluate and compare the susceptibility of chimpanzee versus human peripheral blood mononuclear cells (PBMCs) to infection with SIVcpz and HIV-1 non-syncitium inducing primary isolates. The results demonstrate clearly that chimpanzee PBMCs have a lower capacity to support viral replication as compared to human PBMCs. There was no experimental evidence that this difference was due to a lower availability of target cells for viral infection (PBMCs positive for CD4 and CCR5 molecules) or to a differential susceptibility to apoptosis (PBMCs positive for CD4 and CD95 molecules). A lower capacity of chimpanzee PBMCs to support SIVcpz and HIV-1 replication in vitro is related to a post-entry barrier to virus replication.

Animals↗

PubMed1978

Experimental infection of chimpanzees with the Norwalk agent of epidemic viral gastroenteritis.

A fecal filtrate of human origin containing the Norwalk agent of epidemic viral gastroenteritis was administered by stomach tube to chimpanzees in an attempt to induce diarrheal disease. Significant postchallenge serum antibody rises against Norwalk viral antigens were demonstrated in all animals using the techniques of immune electron microscopy and radioimmunoassay. In addition, viral antigens were detected in feces from five of nine animals using radioimmunoassay. Clinical illness characterized by diarrhea and/or vomiting did not occur. Infection was transmitted subsequently by feeding four additional chimpanzees a fecal filtrate prepared from one of the previously infected animals. Development of an antibody response in four animals and detection of viral antigen in two animals that received this passage filtrate indicated that viral replication had occurred in the absence of clinical illness. The availability of the chimpanzee as an experimental animal host susceptible to infection with the Norwalk agent should facilitate the study of epidemic viral gastroenteritis.

Animals↗

PubMed1980

Transmission of human non-A, non-B hepatitis to chimpanzees following failure to transmit GB agent hepatitis.

Two colony-born infant chimpanzees were inoculated with documented infectious serum containing the GB agent. Serum aminotransferase levels remained within normal limits in weekly serum samples, and no abnormalities were detected in weekly liver biopsy specimens. Each of these chimpanzees was subsequently inoculated with serum containing an agent of human non-A, non-B hepatitis. Each developed non-A, non-B hepatitis characterized by elevation of serum aminotransferase levels and histopathologic changes in liver biopsy specimens. Thus, the chimpanzee appears not to be susceptible to the GB agent, and prior inoculation with this agent does not appear to confer immunity to subsequent infection with human non-A, non-B hepatitis.

Alanine Transaminase↗

PubMed1983

Ultrastructural alterations in hepatocytes and sinus endothelia in experimental non-A, non-B hepatitis in chimpanzees with and without immunoglobulin prophylaxis.

Three chimpanzees were inoculated with an infectious factor VIII preparation. Two of the chimpanzees received in addition a human immunoglobulin preparation as used for prophylaxis in humans. All three chimpanzees developed an acute limited non-A, non-B hepatitis as judged from light and electron microscopic markers after an incubation period of two weeks. The use of immunoglobulin did not prevent the infection. A prolonged incubation of 15 weeks, however, was observed in one animal when alanine aminotransferase (ALT) elevation was used as criterion of infection. In the electron microscope, non-A, non-B hepatitis was characterized by tubular structures, spongelike inclusions and attaching curved membranes, in the absence of nuclear viruslike particles. An additional finding were viruslike particles in crystalline arrays which were found in the cytoplasm of sinusoidal-lining endothelial cells and tubuloreticular complexes.

Animals↗

PubMed1988

Successful postexposure vaccination against hepatitis B in chimpanzees.

To study the effect of postexposure vaccination, four chimpanzees were vaccinated with hepatitis B (HB) vaccine 4, 8, 48, and 72 hr, respectively, after intravenous injection of an infectious hepatitis B virus (HBV) inoculum. The second and third vaccine inoculations were given 2 and 6 weeks later, i.e., at considerably shorter intervals than recommended either for ordinary prophylactic vaccination or for postexposure vaccination in combination with hepatitis B immune globulin (HBIG). The chimpanzees were followed for 1 year. None showed HBs-antigenemia, liver enzyme elevation (ALT), or histopathological alterations in liver biopsies. Late appearance of anti-HBc was observed only in the serum of the animal whose series of vaccination started 72 hr after HBV inoculation. An unvaccinated control chimpanzee, which received the HBV inoculum only, developed clinical hepatitis B with ALT-elevations and HBs-antigenemia within 2 months of the experimental HBV inoculation. These results indicate that postexposure vaccination against hepatitis B begun within 48 hr after HBV exposure, with short intervals between the vaccine injections, can protect against hepatitis B infection also when concomitant HBIG-prophylaxis is not given.

Animals↗

PubMed1991

Hepatitis delta virus cDNA sequence from an acutely HBV-infected chimpanzee: sequence conservation in experimental animals.

Hepatitis delta virus (HDV) RNA was isolated from the serum of a chimpanzee acutely infected with hepatitis B virus (HBV) and superinfected with HDV. Interference of HDV with HBV resulted in decreased HBV DNA levels in the serum. This interference did not change the size of the two HBV specific RNAs present in the liver of the chimpanzee. The complete cDNA sequence of the HDV RNA (5th passage) was determined. Comparison of this cDNA sequence with our previously published sequence (4th passage), located in the variable domain of HDV, was highly conserved. The HDV strain used for these infections originated from a human HDV isolate also used for five to seven HDV passages in chronic HBV carrier chimpanzees (subtypes adw and ayw) or woodchucks chronically infected with woodchuck hepatitis virus (WHV). The complete HDV cDNA sequence showed an extreme conservation (up to 99.8% homology) with the previously published animal-derived HDV cDNA sequences irrespective of passage number and animal species. In contrast a markedly lower homology (85-89%) was found when compared with 3 human-derived HDV cDNA sequences. Comparison of our complete cDNA sequence with the human-derived cDNA sequences showed that the nucleotide changes in the human-derived isolates were restricted to specific regions on the genome and to specific basepair substitutions. The hepatitis Delta antigen (HDAg) is highly conserved both in the human- and animal-derived cDNA sequences showing mainly conservative amino acid changes.

Acute Disease↗

PubMed1999

Female reproductive strategies, paternity and community structure in wild West African chimpanzees.

Although the variability and complexity of chimpanzee behaviour frustrates generalization, it is widely believed that social evolution in this species occurs in the context of the recognizable social group or community. We used a combination of field observations and noninvasive genotyping to study the genetic structure of a habituated community of 55 wild chimpanzees, Pan troglodytes verus, in the Taï Forest, Côte d'Ivoire. Pedigree relationships in that community show that female mate choice strategies are more variable than previously supposed and that the observed social groups are not the exclusive reproductive units. Genetic evidence based on nuclear microsatellite markers and behavioural obser-vations reveal that females in the Taï forest actively seek mating partners outside their social unit; noncommunity males accounted for half the paternities over 5 years. This female mating strategy increases male gene flow between communities despite male philopatry, and negates the predicted higher relatedness among community males. Kin selection seems unlikely to explain the frequent cooperation and sharing observed among group males in this population. Similarly, inbreeding avoidance is probably not the sole cause of permanent adolescent female dispersal as a combination of extragroup mating and avoidance of incest with home group males would allow females to avoid inbreeding without the hazards associated with immigration into a new community. Extragroup mating as part of chimpanzee females' reproductive strategy may allow them to choose from a wider variety and number of males, without losing the resources and support provided by their male social group partners. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1999

Does learning affect the structure of vocalizations in chimpanzees?

We recorded 'pant-hoot' vocalizations from male chimpanzees, Pan troglodytes, housed in two captive facilities in the U.S.A., Lion Country Safari and North Carolina Zoological Park. Acoustic analysis revealed significant differences between the two groups in the temporal patterning of the calls. Because the captive males within each group are from diverse origins, within-group similarity in pant-hoot structure could not have resulted from genetic similarity of the callers. In addition, there were no obvious differences in housing conditions that could have caused the between-group differences. Instead, the results suggest that the calls in each group converged in structure as a consequence of vocal learning. Within-group variation in call structure of the captive groups was similar to that found in a group of wild Ugandan chimpanzees (Kanyawara study group, Kibale National Park), suggesting the presence of species-specific constraints on this call within which different populations can converge on local variants. In addition, an acoustically novel pant-hoot variant that was introduced by one male to the Lion County Safari colony spread to five other males in the same colony. This suggests that chimpanzees may also be able to modify the frequency parameters of their calls through learning. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed2000

Male affiliation, cooperation and kinship in wild chimpanzees.

Long-term field research has revealed that male chimpanzees, Pan troglodytes, affiliate and cooperate in several contexts. Assuming close genetic relationship among males, affiliative and cooperative behaviour have been hypothesized to evolve through the indirect effects of kin selection. We tested the hypothesis that matrilineal genetic relatedness affects patterns of male social affiliation and cooperation in an unusually large community of chimpanzees at the Ngogo study site, Kibale National Park, Uganda. Field observations indicated that six behavioural measures of affiliation and cooperation among 23 adult males were significantly correlated with each other. Sequences of the first hypervariable portion of the mtDNA genome revealed that three pairs of males and one quintet shared mtDNA haplotypes. Matrix permutation tests using behavioural and genetic data showed that males that affiliated and cooperated with each other were not closely related through the maternal line. These findings add to a growing body of empirical evidence that suggest kinship plays an ancillary role in structuring patterns of wild chimpanzee behaviour within social groups. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1994

Conservation of human chromosome 13 polymorphic microsatellite (CA)n repeats in chimpanzees.

Tandemly repeated (dC-dA)n.(dG-dT)n sequences occur abundantly and are found in most eukaryotic genomes. To investigate the level of conservation of these repeat sequences in nonhuman primates, we have analyzed seven human chromosome 13 dinucleotide (CA)n repeat loci in chimpanzees by DNA amplification using primers designed for analysis of human loci. Comparable levels of polymorphism at these loci in the two species, revealed by the number of alleles, heterozygosity, and allele sizes, suggest that the (CA)n repeat arrays and their genomic locations are highly conserved. Even though the proportion of shared alleles between the two species varies enormously and the modal alleles are not the same, allelic lengths at each locus in the chimpanzees are detected within the bounds of the allele size range observed in humans. A similar observation has been noted in a limited number of gorillas and orangutans. Using a new measure of genetic distance that takes into account the size of alleles, we have compared the genetic distance between humans and chimpanzees. The genetic distance between these two species was found to be ninefold smaller than expected assuming there is no selection or mutational bias toward retention of (CA)n repeat arrays. These findings suggest a functional significance for these microsatellite loci.

Alleles↗

PubMed1996

Characterization of a chromosome-specific chimpanzee alpha satellite subset: evolutionary relationship to subsets on human chromosomes.

Alpha satellite DNA is a tandemly repeated DNA family found at the centromeres of all primate chromosomes examined. The fundamental repeat units of alpha satellite DNA are diverged 169- and 172-bp monomers, often found to be organized in chromosome-specific higher-order repeat units. The chromosomes of human (Homo sapiens (HSA)), chimpanzee (Pan troglodytes (PTR) and Pan paniscus), and gorilla (Gorilla gorilla) share a remarkable similarity and synteny. It is of interest to ask if alpha satellite arrays at centromeres of homologous chromosomes between these species are closely related (evolving in an orthologous manner) or if the evolutionary processes that homogenize and spread these arrays within and between chromosomes result in nonorthologous evolution of arrays. By using PCR primers specific for human chromosome 17-specific alpha satellite DNA, we have amplified, cloned, and characterized a chromosome-specific subset from the PTR chimpanzee genome. Hybridization both on Southern blots and in situ as well as sequence analysis show that this subset is most closely related, as expected, to sequences on HSA 17. However, in situ hybridization reveals that this subset is not found on the homologous chromosome in chimpanzee (PTR 19), but instead on PTR 12, which is homologous to HSA 2p.

Animals↗