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PubMed1986

Evolution of glycophorin A in the hominoid primates studied with monoclonal antibodies, and description of a sialoglycoprotein analogous to human glycophorin B in chimpanzee.

Comparison of human and primate erythrocyte membrane sialoglycoproteins showed that common chimpanzee, dwarf chimpanzee, gorilla, orangutan, and gibbon have major periodic acid Schiff-positive proteins resembling human glycophorin A (GPA) monomer and dimer in electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels. Immunoperoxidase staining of Western blots with monoclonal antibodies to human GPA showed that these primate bands express some GPA antigenic determinants. A new sialoglycoprotein analogous to human glycophorin B (GPB) was detected in common chimpanzee. Although human MN blood group phenotype results from an amino acid polymorphism of GPA, Western blots showed that in chimpanzee sialoglycoprotein (GPAch) always expresses the M blood group, whereas chimpanzee sialoglycoprotein (GPBch) expresses either the N blood group or a null phenotype. This result explains the detection of M and MN, but not of N, blood group phenotypes in chimpanzee. GPBch has higher apparent m.w. than human GPB, is present in the erythrocyte membrane in greater quantity than human GPB, and contains trypsin cleavage site(s) and the 10F7 determinant (both found on human GPA but not GPB). Expression of human GPA antigenic determinants was consistent with the phylogeny of the hominoid primates; common and dwarf chimpanzee expressed most of the determinants tested, gorilla and orangutan an intermediate number, and gibbon and siamang the least. Of the GPA antigenic determinants examined, the MN blood group determinants were most consistently expressed during evolution of the hominoid primates. The results suggested that variability in expression of GPA antigenic determinants between species was due to both differences in amino acid sequence and glycosylation.

Adult↗
PubMed1984

Predisposition to invasive pneumococcal illness following parainfluenza type 3 virus infection in chimpanzees.

An outbreak of invasive disease, including pneumococcal bacteremia, meningitis, and pneumonia, involved 17 of 83 (20.5%) chimpanzees at a primate rehabilitation unit. Invasive disease was more common in splenectomized than in nonsplenectomized animals (42.9% vs 18.4%), but the difference was not statistically significant. The outbreak followed closely an outbreak of upper respiratory tract infection (URTI) that occurred with equal frequency in splenectomized and nonsplenectomized chimpanzees. Those with URTI were 5.7 times as likely to develop invasive disease than those without URTI (P less than 0.005). Fourteen of 20 (70%) chimpanzees with recent URTI and serologically examined had a 4-fold or greater rise in titer to parainfluenza type 3 virus. The outbreak of invasive disease occurred despite the fact that most of the chimpanzees had been vaccinated with pneumococcal vaccine. Efficacy of pneumococcal vaccine could not be demonstrated among any segment of the chimpanzee population, and testing of sera from 23 vaccinated chimpanzees against 4 pneumococcal serotypes (3, 6, 8, and 14) failed to show a meaningful immune response. The findings demonstrated that viral URTI can predispose primates to invasive infections and suggested that pneumococcal vaccine is not protective in chimpanzees.

Adult↗
PubMed1994

Genetic polymorphism of apolipoprotein A-IV in the chimpanzee: common deletion of a conserved 12-nucleotide tandem repeat.

Apolipoprotein A-IV (apoA-IV protein; APOA4 gene) is structurally polymorphic in various mammalian species, including human, baboon, dog, horse, and mouse. To analyze the extent of genetic variation in the chimpanzee APOA4 gene, we screened 115 common chimpanzees (Pan troglodytes) (86 unrelated wild captured parents and 29 captive-born offspring) using isoelectric focusing followed by immunoblotting for protein polymorphism and using polymerase chain reaction (PCR) assay for DNA polymorphism. At the protein level the unrelated sample of chimpanzees is highly variable, having four alleles, APOA4*1, APOA4*2, APOA4*3, and APOA4*4, with frequencies of 0.192, 0.430, 0.331, and 0.047, respectively. The chimpanzee APOA4 locus, with four common alleles and a gene diversity of 67%, is more variable than previously reported variations in baboons (five alleles with 52% gene diversity) and humans (two alleles with 15% gene diversity). PCR amplification of chimpanzee DNAs, using a pair of human oligonucleotide primers covering a region of 300 nucleotides in the third exon, revealed a common 12-nucleotide deletion (allele frequency = 0.192) that correlates exactly with the APOA4*1 allele detected by isoelectric focusing and immunoblotting. DNA sequencing of the 300-nucleotide PCR amplified product revealed the deletion of 12 nucleotides near the carboxyl terminal region of the mature apoA-IV protein. This in-frame deletion, which codes for and eliminates four amino acids [glutamic acid (GAG), glutamine (CAG), glutamine (CAG), and glutamine (CAG)], occurs in a region that is evolutionarily conserved among rats, mice, chimpanzees, and humans. The partial DNA sequencing of the 3' end of the chimpanzee APOA4 gene revealed 99% identity with the human APOA4 gene.

Alleles↗
PubMed1994

Comparison of anti-HIV-1 ADCC reactivities in infected humans and chimpanzees.

Despite its shortcomings as a disease model, the chimpanzee is still the most relevant animal model for human immunodeficiency virus type 1 (HIV-1) infection. Previous studies have revealed qualitative differences between human and chimpanzee anti-HIV-1 responses. In this study, the development of specific anti-HIV-1 antibody-dependent cellular cytotoxic (ADCC) reactivities was evaluated in chronically infected chimpanzees and compared to the human response, because anti-HIV-1 ADCC represents a major component of anti-envelope cytolytic response found in infected patients. Ten HIV-1-infected chimpanzees up to 5 years after the infection were investigated. Anti-HIV-1 ADCC-directing antibodies were detectable in only three of 10 infected chimpanzees, and in these animals, activity was apparent only several months after the HIV infection. In some of the infected animals, ADCC reactivity against infected cells preceded reactivity against gp120-coated targets. When anti-gp120 ADCC-directing antibodies were apparent, they exhibited the same broad reactivity described in humans against different HIV isolates. The pattern of ADCC reactivities in infected chimpanzees is completely different from the well-characterized anti-gp120 cytotoxic reactivities present in HIV-1-infected patients. It is a relatively rare and late-occurring event that may have an important bearing on the lack of virus-induced pathogenesis in the chimpanzee model.

Animals↗
PubMed1996

Dental development in chimpanzees (Pan troglodytes): the timing of tooth calcification stages.

Data are presented documenting the timing of tooth calcification for the left mandibular dentition (I1-M3) based on a cross-sectional series of intraoral dental X-rays from a sample of 118 captive chimpanzees. Mean, median, and midpoint ages of attainment; standard deviations (SD); interquartile ranges (IQR); and age ranges were calculated for the eight developmental stages of these teeth. Minor differences with previous studies of chimpanzee dental development were found (Anemone et al. [1991] Am. J. Phys. Anthropol. 86:229-241; Anemone and Watts [1992] J. Hum. Evol. 22:149-153), but the similarities with previous studies are more striking despite the differences in samples. In contrast to other pongid studies, sex differences in developmental timing were documented, particularly for the canine. Regression models for age estimation from dental maturity scores were also presented. This chimpanzee standard is compared with human standards to determine absolute and relative differences in the timing of crown and root calcification. The overall period of canine development in both species is nearly identical, although those for crown and root formation are markedly different--making this tooth the most distinctive feature between chimpanzee and human dental development periods. Although the molars demonstrate differences in the timing of crown and root calcification periods, they are more proportional than for other teeth. This contributes to the difficulties in distinguishing between "human" and "chimpanzee" patterns of molar development. The developmental differences discussed are placed in perspective with consideration to microstructural and morphological features of chimpanzee and human teeth, and to overall growth periods in these species.

Animals↗
PubMed1996

Comparison of diaphyseal growth between the Libben Population and the Hamann-Todd chimpanzee sample.

The differences in limb lengths and proportions between humans and chimpanzees are widely known. Humans have relatively shorter forelimbs and longer hind limbs than chimpanzees. Humans have a longer period of long bone formation than chimpanzees. Recent advances in estimating age-at-death in chimpanzees from their dentition have allowed us to reexamine long bone growth in chimpanzees using their skeletal remains and compare it with similar data for humans. A chronological normalization procedure allowing direct interspecific comparison of long bone growth is presented. The preadult chimpanzee sample (n = 43) is from the Hamann-Todd Osteological Collection from the Cleveland Museum of Natural History. All human specimens (n = 202) are from the late Woodland Libben Population currently housed at Kent State University. Relying on these cross-sectional data, we conclude that both species elongate their femora at similar absolute (length per unit time) but different relative (length relative to normalized dental age) rates. The species differ in the absolute growth rate of the humerus but share a common normalized rate of growth. Forelimb segment proportion differences between species are due to differential elongation rates of the segments. Hind limb diaphyseal proportions are the same in both species, which suggests that changes in segment length are proportional. Therefore, alternative developmental mechanisms exist in these closely related species which can produce changes in limb length.

Animals↗
PubMed1998

Dietary responses to fruit scarcity of wild chimpanzees at Bossou, Guinea: possible implications for ecological importance of tool use.

A 13-month ecological study was conducted at Bossou, Guinea, West Africa, to elucidate how a community of wild chimpanzees (Pan troglodytes verus) deals with the scarcity of main foods. During the study period, fruit availability fluctuated radically. The chimpanzees were confirmed to depend heavily on three "keystone resources" which were available when their main foods (fruit pulp) were scarce. These were fruits of Musanga cecropioides, oil-palm (Elaeis guineensis) nuts, and oil-palm pith. These are abundant in the chimpanzees' home range and their nutritional contents compensate for a decrease in nutritional intake from fruit pulp. The presence of these excellent backup foods may explain the high reproductive performance of Bossou chimpanzees. Here, chimpanzees consumed two of the three keystone foods using two types of tool behavior: nut-cracking for oil-palm nuts and pestle-pounding for oil-palm pith. These tool-using behaviors accounted for 31.9% of the total feeding time spent in June (the month in which the highest frequency occurred) and 10.4% in total for the year. It is suggested that the Bossou chimpanzees depend strongly on tools for their subsistence. This implies a possible function for tool technology in the evolution of our human ancestors.

Animals↗
PubMed1999

Geographic variation in the calls of wild chimpanzees: a reassessment.

Male chimpanzees produce a species-typical call, the pant hoot, to communicate to conspecifics over long-distances. Calls given by males from the well-known Gombe and Mahale populations typically consist of four different phases: an introduction, build-up, climax, and let-down. Recent observations suggest that chimpanzees living in the Kibale National Park, Uganda, consistently give calls that lack a build-up and are thus qualitatively distinguishable acoustically from those made by other East African conspecifics. We analyzed additional recordings from Mahale and Kibale to re-examine geographic variation in chimpanzee calls. Results indicate that males from both sites produce pant hoots containing all four parts of the call. Calls made by chimpanzees from the two populations, however, differ in quantitative acoustic measures. Specifically, males at Kibale initiate their calls with significantly longer elements and build-up over briefer periods at slower rates than individuals from Mahale. Kibale males also deliver acoustically less variable calls than chimpanzees at Mahale. Although climax elements do not differ between populations in any single acoustic feature, discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct population at rates higher than that expected by chance. Ecological factors related to differences in habitat acoustics, the sound environment of the local biota, and body size are likely to account for these observed macrogeographic variations in chimpanzee calls.

Animals↗
PubMed2000

Videotapes as enrichment for captive chimpanzees (Pan troglodytes).

The effectiveness of showing videotapes to captive chimpanzees as an environmental enrichment was quantitatively tested. The responses of 10 subjects (3 adult males and 7 adult females) to videotapes of chimpanzees engaging in a variety of behaviors, to videotapes of other animals and humans, and to television programs were compared. Data collection consisted of 20-minute, continuous sampling tests while various videotapes were shown. A total of 400 tests were conducted. Multivariate analysis of variance was applied to measure differences in the duration of eight categories of behavior across videotapes of varying content. No general behavioral differences in response to the tapes based on sex or housing were revealed. However, with the behavior of monitor-watching analyzed alone, we found that individually housed subjects watched the videotapes more than socially housed subjects. When viewing time was averaged across all videotapes, the chimpanzees watched the monitor a mean of 38.4% of the time available. The chimpanzees' behavior varied significantly only when they were watching the videotapes of various human and chimpanzee activities and not when watching a blank screen. A Pearson's correlation indicated that subjects habituated to repeated presentations of the videotapes, although the effect was small numerically. Although this type of enrichment did not extensively alter behavior, it did occupy a significant portion of the subjects' activity budget; thus, the amount of time spent watching the video stimuli indicated that videotapes may be a useful enrichment for captive chimpanzees. Zoo Biol 19:541-551, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗
PubMed2005

Fifty years of chimpanzee demography at Taronga Park Zoo.

There has been a captive Pan troglodytes colony at Taronga Park Zoo in Sydney, Australia, since the mid-1930s. Demographic data on these animals were first analyzed in 1986; however, further information collected for 15 years since then is now available. The reproductive histories of 33 females in the colony have been recorded, and these data form the largest collection of captive chimpanzee data from a setting that has involved natural breeding conditions since the mid-1960s. These data were analyzed in conjunction with data from wild populations to establish the degree of variability present within chimpanzee reproductive parameters, and to identify which distinctive life history characteristics persist in well-provisioned, natural-fertility populations. The age at first birth for the chimpanzee females is 9.8 yr on average (n=16), which is 1-4.8 yr earlier than the average for wild populations. In line with this accelerated reproduction, birth intervals are also significantly shorter than those in noncaptive chimpanzee populations. The median birth interval for all surviving infants (based on a Kaplan-Meier survival analysis) is 49 months (n=43) compared to 62+ months for wild groups. At the same time, infant mortality remains high. The data confirm distinctive features of the life history of common chimpanzees, including later maturation, long birth intervals, a relatively invariant fertility schedule, and high juvenile mortality. However, aspects of both fertility and mortality are significantly related to social circumstances, indicating that in common chimpanzees, as in humans, life history characters may represent ecological and social adaptations rather than species-fixed characteristics.

Age Factors↗
PubMed2002

Ontogenetic study of the skull in modern humans and the common chimpanzees: neotenic hypothesis reconsidered with a tridimensional Procrustes analysis.

Heterochronic studies compare ontogenetic trajectories of an organ in different species: here, the skulls of common chimpanzees and modern humans. A growth trajectory requires three parameters: size, shape, and ontogenetic age. One of the great advantages of the Procrustes method is the precise definition of size and shape for whole organs such as the skull. The estimated ontogenetic age (dental stages) is added to the plot to give a graphical representation to compare growth trajectories. We used the skulls of 41 Homo sapiens and 50 Pan troglodytes at various stages of growth. The Procrustes superimposition of all specimens was completed by statistical procedures (principal component analysis, multivariate regression, and discriminant function) to calculate separately size-related shape changes (allometry common to chimpanzees and humans), and interspecific shape differences (discriminant function). The results confirm the neotenic theory of the human skull (sensu Gould [1977] Ontogeny and Phylogeny, Cambridge: Harvard University Press; Alberch et al. [1979] Paleobiology 5:296-317), but modify it slightly. Human growth is clearly retarded in terms of both the magnitude of changes (size-shape covariation) and shape alone (size-shape dissociation) with respect to the chimpanzees. At the end of growth, the adult skull in humans reaches an allometric shape (size-related shape) which is equivalent to that of juvenile chimpanzees with no permanent teeth, and a size which is equivalent to that of adult chimpanzees. Our results show that human neoteny involves not only shape retardation (paedomorphosis), but also changes in relative growth velocity. Before the eruption of the first molar, human growth is accelerated, and then strongly decelerated, relative to the growth of the chimpanzee as a reference. This entails a complex process, which explains why these species reach the same overall (i.e., brain + face) size in adult stage. The neotenic traits seem to concern primarily the function of encephalization, but less so other parts of the skull. Our results, based on the discriminant function, reveal that additional structural traits (corresponding to the nonallometric part of the shape which is specific to humans) are rather situated in the other part of the skull. They mainly concern the equilibrium of the head related to bipedalism, and the respiratory and masticatory functions. Thus, the reduced prognathism, the flexed cranial base (forward position of the foramen magnum which is brought closer to the palate), the reduced anterior portion of the face, the reduced glabella, and the prominent nose mainly correspond to functional innovations which have nothing to do with a neotenic process in human evolution. The statistical analysis used here gives us the possibility to point out that some traits, which have been classically described as paedomorphic because they superficially resemble juvenile traits, are in reality independent of growth.

Animals↗
PubMed1989

Hunting behavior of wild chimpanzees in the Taï National Park.

Hunting is often considered one of the major behaviors that shaped early hominids' evolution, along with the shift toward a drier and more open habitat. We suggest that a precise comparison of the hunting behavior of a species closely related to man might help us understand which aspects of hunting could be affected by environmental conditions. The hunting behavior of wild chimpanzees is discussed, and new observations on a population living in the tropical rain forest of the Taï National Park, Ivory Coast, are presented. Some of the forest chimpanzees' hunting performances are similar to those of savanna-woodlands populations; others are different. Forest chimpanzees have a more specialized prey image, intentionally search for more adult prey, and hunt in larger groups and with a more elaborate cooperative level than savanna-woodlands chimpanzees. In addition, forest chimpanzees tend to share meat more actively and more frequently. These findings are related to some theories on aspects of hunting behavior in early hominids and discussed in order to understand some factors influencing the hunting behavior of wild chimpanzees. Finally, the hunting behavior of primates is compared with that of social carnivores.

Animals↗
PubMed1993

Comparative locomotor behavior of chimpanzees and bonobos: the influence of morphology on locomotion.

Results from a 10 month study of adult male and female bonobos (Pan paniscus) in the Lomako Forest, Zaire, and those from a 7 month study of adult male and female chimpanzees in the Tai Forest, Ivory Coast (Pan troglodytes verus), were compared in order to determine whether there are species differences in locomotor behavior and substrate use and, if so, whether these differences support predictions made on the basis of interspecific morphological differences. Results indicate that bonobos are more arboreal than chimpanzees and that male bonobos are more suspensory than their chimpanzee counterpart. This would be predicted on the basis of male bonobo's longer and more narrow scapula. This particular finding is contrary to the prediction that the bonobo is a "scaled reduced version of a chimpanzee" with little or no positional behavior difference as had been suggested. This study provides the behavioral data necessary to untangle contradictory interpretations of the morphological differences between chimpanzees and bonobos, and raises a previously discussed (Fleagle: Size and Scaling in Primate Biology, pp. 1-19, 1985) but frequently overlooked point--that isometry in allometric studies does not necessarily equate with behavioral equivalence. Several researchers have demonstrated that bonobos and chimpanzees follow the same scaling trends for many features, and are in some sense functionally equivalent, since they manage to feed and reproduce. However, as reflected in their morphologies, they do so through different types and frequencies of locomotor behaviors.

Animals↗
PubMed1980

Non-A/non-B hepatitis in experimentally infected chimpanzees: cross-challenge and electron microscopic studies.

Inoculation of eight chimpanzees with factor VIII, factor IX, or "H" strain plasma resulted in enzymatic and histopathologic evidence of non-A/non-B hepatitis in all eight animals. Challenge of two chimpanzees convalescent from factor VIII-induced disease with either factor IX or "H" strain plasma resulted in non-A/non-B hepatitis only in the animal inoculated with factor IX materials. Reciprocal cross-challenge of a chimpanzee convalescent from factor IX-induced disease with factor VIII also produced unequivocal enzymatic and histopathologic evidence of non-A/non-B hepatitis. Cross-challenge of a chimpanzee convalescent from "H" strain-induced non-A/non-B hepatitis with factor VII did not cause a second bout of non-A/non-B hepatitis. These findings suggest the factor VIII materials and "H" strain plasma used in these studies share a common etiologic agent (or agents), but that factor VIII and factor IX may contain two distinct agents. Electron microscopic (EM) examination of thin-sectioned, acute-phase liver biopsies from all but one of the chimpanzees receiving the primary inocula revealed the presence of abnormal hepatocyte cytoplasmic structures previously shown to be associated with non-A/non-B hepatitis. Crystalline structure containing 25 to 30 nm particles were visualized by EM in the cytoplasm of endothelial or Kupffer cells in acute-phase liver biopsies obtained from three chimpanzees inoculated with either factor VIII materials or "H" strain plasma.

Animals↗
PubMed1983

Non-A, non-B hepatitis in chimpanzees: interference with acute hepatitis A virus and chronic hepatitis B virus infections.

Two chimpanzees with persistent non-A, non-B (NANB) hepatitis were superinfected with marmoset-passaged MS-1 HAV. Two control chimpanzees were also infected with marmoset-passaged HAV. Neither animal with persistent NANB hepatitis developed elevated alanine aminotransferase (ALT) activity, whereas both control chimpanzees exhibited ALT elevations within 3 weeks after inoculation. In addition, both NANB-infected chimpanzees demonstrated a delayed anti-HAV antibody response in which one animal failed to produce detectable IgM anti-HAV. With the exception of one stool, all serial liver biopsy specimens and daily stool suspensions from the superinfected chimpanzees were negative for HAV antigen. One chimpanzee with a chronic HBV infection was superinfected with non-A, non-B hepatitis and was shown to develop elevated ALT activity and hepatocyte ultrastructural alterations accompanied by a marked reduction in the titer of serum HBsAg. Our combined findings indicate that acute and persistent non-A, non-B hepatitis infections are capable of interferring with two distinctly different hepatotropic viruses. These results also suggest that in vitro detection of non-A, non-B hepatitis infection or virus(es) may be achieved by antibody-independent methodologies that employ the basic principle of viral interference.

Alanine Transaminase↗
PubMed1985

Absence of detectable hepatitis B virus DNA in sera and liver of chimpanzees with non-A, non-B hepatitis.

The risk of hepatitis B infections has been reduced by screening of blood donors for hepatitis B surface antigen (HBsAg). However, recipients remain at significant risk of developing post-transfusion hepatitis. Studies have shown that non-A, non-B hepatitis virus(es) are responsible for the majority of post-transfusion hepatitis infections. In spite of many efforts, these non-A, non-B hepatitis viruses have not yet been identified. Epidemiological studies, however, suggest that non-A, non-B hepatitis shares many features with hepatitis B. Recently, Wands et al [1982] showed, in chimpanzees infected with non-A, non-B hepatitis agents, the presence of antigenemia or viremia by radioimmunoassay with monoclonal antibodies directed toward distinct determinants of HBsAg and by molecular hybridization analysis. They suggested that non-A, non-B hepatitis agents may be related, but distinct variant(s) of hepatitis B virus (HBV). In this study, five chimpanzees were inoculated with three different agents that have been shown to transmit non-A, non-B hepatitis. The following inocula were used (I) a factor VIII preparation kindly provided by D.W. Bradley, (II) acute phase serum from a chimpanzee infected with the F strain kindly provided by A.J. Zuckerman, and (III) a DS-antigen serum previously shown by us to transmit non-A, non-B hepatitis [Duermeyer et al, 1983]. All chimpanzees developed a rise in transaminase levels between 8 and 10 weeks after inoculation. None of the chimpanzees was positive for any markers of HBV infection. No evidence was obtained of infection with hepatitis A, cytomegalovirus, or Epstein-Barr virus. One chimpanzee developed chronic liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Transmission of HCV to a chimpanzee using virus particles produced in an RNA-transfected HepG2 cell culture.

It was demonstrated previously that HepG2 cells produce negative strand RNA and virus-like particles after transfection with RNA transcribed from a full-length hepatitis C virus (HCV) cDNA clone [Dash et al. (1997) American Journal of Pathology, 151:363-373]. To determine in vivo infectivity of these in vitro synthesized viral particles, a chimpanzee was inoculated intravenously with HCV derived from HepG2 cells. The infected chimpanzee was examined serially for elevation of liver enzymes, for the presence of HCV RNA in the serum by reverse transcription nested polymerase chain reaction (RT-PCR), anti-HCV antibodies in the serum, and inflammation in the liver. The chimpanzee developed elevated levels of liver enzymes after the second week, but the levels fluctuated over a 10-week period. HCV RNA was detected in the serum of the chimpanzee at the second, seventh and ninth weeks after inoculation, and remained positive up to 25 weeks. Liver biopsies at Weeks 18 and 19 revealed of mild inflammation. Nucleotide sequence analysis of HCV recovered from the infected chimpanzee at the second and ninth weeks showed 100% sequence homology with the clone used for transfection studies. Serum anti-HCV antibodies were not detected by EIA during the 25 weeks follow-up period. These results suggest that intravenous administration of the virus-like particles derived from RNA-transfected HepG2 cells are infectious, and therefore, the pMO9.6-T7 clone is an infectious clone. These results provide new information that in vitro synthesized HCV particles produced from full-length HCV clone can cause infection in a chimpanzee. This study will facilitate the use of innovative approaches to the study of assembly of HCV particles and mechanisms of virus infectivity in cell culture.

Alanine Transaminase↗
PubMed2000

Vocal responsiveness in male wild chimpanzees: implications for the evolution of language.

Several captive chimpanzees and bonobos have learned to use symbols and to comprehend syntax. Thus, compared with other nonhumans, these animals appear to have unusual cognitive powers that can be recruited for communicative behavior. This raises the possibility that wild chimpanzee vocal communication is more complex than heretofore demonstrated. To examine this possibility, I investigated whether wild chimpanzee vocal exchanges exhibit uniquely human conversational attributes. The results indicate that wild chimpanzees vocalize at low rates, tend not to respond to calls that they hear, and, when they do respond, tend to give calls that are similar to the ones they have heard. Thus, chimpanzee vocal interactions resemble those of other primate species, and show no special similarity to human conversations. The results support the view that we need to explore cognitive and social continuities and discontinuities with nonhuman primates to understand the origin and evolution of language, but also emphasize the need for fine-grained analyses of wild chimpanzee vocal interactions.

Animals↗