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PubMed1989

Splitting of the circadian activity rhythm in common marmosets (Callithrix j. jacchus; primates).

Long-term recordings of the free-running circadian activity rhythm in common marmosets, Callithrix j. jacchus, living under constant environmental conditions (LL 200-470 lx) provided evidence of rhythm splitting in nonhuman primates. In two out of ten test animals two different types of splitting occurred; spontaneous persistent splitting and temporary splitting. Neither a reduction of the illumination intensity nor the application of dark pulses had any effect on the two activity components of the persistently split rhythm.

Activity Cycles↗

PubMed1990

Polyhalogenated dibenzo-p-dioxins and dibenzofurans and the immune system. 1. Effects on peripheral lymphocyte subpopulations of a non-human primate (Callithrix jacchus) after treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

Monoclonal antibodies were used to analyse the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on peripheral lymphocytes from marmosets (Callithrix jacchus) following injections of single low doses of TCDD. A reduction of the percentage and the total number of lymphocytes among the white blood cells was seen 3 weeks after a single administration of 300 ng TCDD/kg body wt, but not following 167 ng TCDD/kg or less. After treatment of marmosets with the single subcutaneous dose of 10 ng TCDD/kg body wt. we observed an average decrease of about 20% in the percentage of CD4+ cells in the venous blood of treated animals. This change was not seen at the time of maximum absorption (2 weeks after the injection), but was demonstrable after 4 weeks and reached its maximum 15 weeks after the injection. The time course of the changes suggests an indirect effect (possibly via the thymus). Due to the considerable inter- and intra-individual variability in the number of peripheral lymphocytes the effect was less convincing on the basis of the total CD4+ cells per microliter blood. There was a significant concomitant increase in the percentage of cells with the CD8+ marker. A closer analysis of the lymphocyte subpopulation involved revealed a predominant effect on the cells with the CD4CDw29 ("leu 3a+4B4+") surface marker ("helper-inducer cells"). Subsequent to a dose of 10 ng TCDD/kg body wt the percentage of these cells was reduced by 50% or more when compared with the (24) controls. On an absolute basis (number of cell/microliter blood) these CD4+CDw29+ cells were clearly reduced in only two out of four marmosets. There was no significant effect on the percentage of the CD4+CD45R+ ("leu3a+2H4+") subpopulation ("suppressor-inducer cells"). The ratios: CD4+CDw29+/CD4+CD45R+, or CD4+CDw29+/CD8+ appear to be convenient measures for monitoring the effect described. Since the difference between the percentage of CD2+ cells minus the sum of CD4+ plus CD8+ cells was found to be increased following rather high doses (167 ng TCDD/kg body wt or more), this suggests that immature cells (CD2+ CD4-CD8-) are released into the periphery as a result of the exposure to TCDD. Furthermore, a decrease in the percentage of CD20+ (B1+) cells (about 50% when compared with controls) was observed in the treated animals following a single dose of 10 ng TCDD/kg body wt or higher. Subsequent to a dose of 10 ng TCDD/kg body wt the percentage of CD56+ (NKH1+) cells seemed to be slightly increased. The dose-response for the effects observed was rather poor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

[Radiotelemetric studies of the body temperature of white-tufted monkeys (Callithrix jacchus)].

A newly developed telemetry system was used to study deep body temperature (BT) of two adult male common marmosets (Callithrix jacchus). The BT-curves of both monkeys showed a similar clear circadian rhythm with a range up to 3.5 degrees C. At environmental temperature of 28 degrees C (ET) the BT of the monkeys varied in the daytime dependent on their spontaneous activity, with little individual differences between 37.5 degrees C and 39.3 degrees C; at night the BT of the remarkably deeply-sleeping animals decreased to an average at 35.8 degrees C. Elevating ET up to 30 degrees C effected an increase of BT by 0.6 degrees C, both during day and night. On the contrary, reducing ET to 24 degrees C the BT increased only at night, by 0.2 degrees C at ad libitum food intake and 1.0 degrees C at fasting. Measurements of BT by inserted rectal thermometer caused, compared with telemetry, an average at 0.4 degrees C higher values.

Animals↗

PubMed1992

Polyhalogenated dibenzo-p-dioxins and dibenzofurans and the immune system. 4. Effects of multiple-dose treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on peripheral lymphocyte subpopulations of a non-human primate (Callithrix jacchus).

Non-human primates (Callithrix jacchus) were treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) over a period of 30 weeks, and lymphocyte subpopulations of venous blood were monitored using monoclonal antibodies and flow cytometry (FACScan). There was no clear-cut change in the total lymphocyte population during this study. In the first part of the study the new-world monkeys (marmosets) were treated for 24 weeks with a weekly dose of 0.3 ng TCDD/kg body wt. At the end of this treatment period a level corresponding to an actual cumulative dose of about 2.5-2.7 ng TCDD/kg body wt was expected. The percentage and the absolute number of the CD4+CDw29+ cells ("helper inducer" or "memory" cells) surmounted the physiologically occurring increase. Concomitantly the percentage of the CD4+CD45RA+ cells ("suppressor-inducer" or "naive" cells) decreased. There was, at the same period, no change in the total T cell population (CD2+ cells) or in the cells carrying the CD8 or the CD4 epitope. When increasing the weekly dose to 1.5 ng TCDD/kg body wt, a transient increase in the percentage and the absolute number of the CD8+CD56+ cell population ("cytotoxic T cells") was observed 3 weeks after the increase in dosing. At this time the expected decrease in the percentage or the absolute number of CD4+CDw29+ cells was just detectable and this decline was at its maximum 6 weeks after switching to the higher weekly doses. The reduction in the percentage and the absolute number of CD4+CDw29+ cells persisted 5 weeks after discontinuation of the dosing, but this cell population was again within normal limits 7 weeks later. Because the two subpopulations are changed in opposite directions, the ratio CD4+CDw29+/CD4+CD45RA+ is a very sensitive measure of the effect induced by TCDD. There was a pronounced decrease in the percentage of the CD20+ cells (B1 cells), but their percentage and number rapidly normalized, in contrast to the CD4+CDw29+ cells, when the dosing was discontinued. At the end of the treatment period the apparent body burden was calculated to correspond to an actual dose of about 9-10 ng TCDD/kg body wt. Such an actual dose level might be assumed to be reached under steady-state conditions in chronic experiments with daily doses of about 135 pg TCDD/kg body wt (assuming a half-life for TCDD in the marmoset of 6-8 weeks). Extrapolations of the results obtained at higher doses to very low exposures is not justified with respect to the effects induced by TCDD on the immune system of marmosets. At lower doses the effect is clearly reversed.

Animals↗

PubMed2002

Behavioral and cardiophysiological responses of common marmosets (Callithrix jacchus) to social and environmental changes.

Under captive conditions common marmosets (Callithrix jacchus) show socially monogamous propensities. Male and female form a social bond as characterized by signs of behavioral arousal during separation of the pairmates, high levels of affiliative interactions between pairmates and agonistic responses towards strange conspecifics. In the present study behavioral and cardiophysiological responses of mated individuals of common marmosets were recorded while the animals were in an unfamiliar environment (1) alone, (2) with the pairmate, or (3) with an opposite-sexed stranger. Pairmates of 6 established pairs were tested in 3 replicates yielding a total of 36 trials per experiment. A trial was divided into three 10-min segments (baseline; unfamiliar environment; reunion). Behavioral responses were videotaped with a remote controlled camera system installed within the cage. Systolic (SBP) and diastolic blood pressure (DBP), and heart rate (HR) as well as locomotor activity (ACT) were recorded telemetrically through peritoneally implanted transmitters. The individuals' responses measured while in an unfamiliar environment was only reduced by the pairmate, but not by an opposite-sexed stranger. No affiliative behaviors occurred between strange conspecifics, whereas aggressive and sexual behaviors were observed. During reunion with the pairmate individuals recovered physiologically. The present study shows that an individualized pair bond exists between pairmates of common marmosets. Further, it becomes evident that establishing a social bond with the pairmate is important for maintaining physiological homeostasis.

Animals↗

PubMed1994

Effects of recombinant human interleukin 6 (rhIL-6) in marmosets (Callithrix jacchus). 1. General toxicity and hematological changes.

The physiological and toxicological properties of recombinant human interleukin 6 (rhIL-6) were assessed in marmoset monkeys (Callithrix jacchus). Two experimental series were performed with daily subcutaneous administration: (a) 5 or 1000 micrograms rhIL-6/kg per day for three weeks and (b) 25, 100 or 500 micrograms rhIL-6/kg per day for 3 months. RhIL-6 was well tolerated and did not induce fever or any other non-specific signs of toxicity. The main findings were: (1) A two- to threefold increase in platelet counts at 2-4 weeks, which decreased following further continuous rhIL-6 administration; (2) increase in total white blood cells between 1 and 4 weeks of administration, including an absolute increase in granulocytes (including band forms) and basophils. A change in the number of monocytes was not detected; (3) an increase in total red blood cells, which peaked at 4 weeks, sustained elevation of red cell distribution width and a slight decrease in hemoglobin between week 1 and 4, concurrent with a distinct decrease in mean corpuscular hemoglobin at 4 weeks. This effect persisted for 9 weeks in the 100 micrograms/kg and 500 micrograms/kg groups; (4) decrease in plasma AST activity and increase in plasma protein concentration after 2 weeks of treatment; (5) no clinical or biochemical signs of renal glomerular dysfunction; (6) RhIL-6 after s.c. administration was detectable in the plasma, peak levels (mean values +/- SD) of 9.4 +/- 6.3 and 72.4 +/- 7.7 ng/ml were measured after a single dose of 100 or 1000 micrograms/kg; (7) antibodies against rhIL-6 developed within 2 weeks, increased during administration and neutralized the biological effect of rhIL-6 progressively from 4 to 9 weeks. In conclusion, aside from a mild anemia, rhIL-6 was well tolerated in marmosets and had a profound and sustained effect on thrombopoiesis. Due to the formation of neutralizing antibodies, the chronic biological effect of rhIL-6 is lost in marmosets and studies beyond 4 weeks are rendered less meaningful. The analyses of antibody formation, induction of acute phase proteins, histological changes and alterations on lymphocyte receptors will be reported in two following publications.

Analysis of Variance↗

PubMed1997

Creation of a model for multiple sclerosis in Callithrix jacchus marmosets.

Multiple sclerosis (MS) is an inflammatory disease of the CNS white matter characterized pathologically by the accumulation of perivascular and parenchymal T lymphocytes (T cells), and macrophage infiltration associated with myelin destruction. MS lesions are also characterized by the death of oligodendrocytes (the myelin-producing cells) and proliferation and hypertrophy of astrocytes with scar tissue (gliosis) replacing normal myelin. These changes result in the loss of axonal conduction for neurons of the CNS and in clinical disability. MS is thought to be an autoimmune disease, in particular because of its analogy with the disease model of experimental allergic encephalomyelitis (EAE). Despite extensive research and the availability of various EAE models in laboratory rodents the etiology of human MS has not been identified, and to date no effective treatment exists. Phylogenetic differences may limit the usefulness of existing EAE models, and indeed no single form of rodent EAE recapitulates all the clinical and pathological features of MS. Here we describe a novel form of EAE created in a nonhuman primate, the common marmoset Callithrix jacchus. Active immunization of these monkeys with whole myelin produces a primary demyelinating disease with a chronic relapsing-remitting course, characterized pathologically by moderate inflammation with prominent and early demyelination and gliosis reminiscent of human MS. Adoptive and passive transfer experiments have permitted definition of the mechanisms responsible for the MS-like pathology. Production of the fully demyelinated lesion requires synergism between encephalitogenic (e.g., disease-inducing) T cells and pathogenic antibody. The antigens of myelin that promote encephalitogenic T cell and antibody responses in this system have been identified. Because of the similarity between the two conditions and the high degree of conservation in immune and nervous system genes between nonhuman primates and humans, future studies of marmoset EAE will likely accelerate the development of therapies for human MS.

Adoptive Transfer↗

PubMed2002

Low doses of 2,3,7,8-tetrachlorodibenzo- p-dioxin increase transforming growth factor beta and cause myocardial fibrosis in marmosets ( Callithrix jacchus).

Epidemiological studies have suggested an association between exposure to dioxins and cardiovascular morbidity and mortality. However, cardiotoxic effects of low doses of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) in animals have not been reported so far. We studied the hearts of male marmosets ( Callithrix jacchus)after treatment with single subcutaneous doses of 1, 10 or 100 ng TCDD/kg body weight or vehicle (toluene/DMSO 1+2 v/v, 100 microl/kg body weight). The animals were killed 2 or 4 weeks after treatment. Tissue samples of left ventricular myocardium were stained with picrosirius red and examined histologically along with quantitative image analysis. Extracellular matrix proteins were additionally analysed by western blotting. Monkeys showed no overt signs of toxicity nor did their relative heart weights differ significantly depending on treatment. Histology revealed an increase of picrosirius red-positive area above control values in 2 of 4 (1 ng TCDD/kg body weight), 6 of 12 (10 ng/kg) and 6 of 10 (100 ng/kg) marmosets. Western blotting confirmed these histological findings showing an increase of collagen, fibronectin and laminin in the hearts of TCDD-treated animals. Western blotting additionally showed an increased concentration of transforming growth factor beta1 (TGF-beta1) as well as TGF-beta receptor type I which could be a functional link to the effects on extracellular matrix. Our findings might explain the association of TCDD exposure with increased cardiovascular mortality observed in epidemiological studies and should stimulate further research on the role of changes in the extracellular matrix in the toxic effects of dioxins and related substances on other organs.

Animals↗

PubMed1994

Embryotoxic effects of thalidomide derivatives in the non-human primate Callithrix jacchus. 5. Lack of teratogenic effects of phthalimidophthalmide.

The teratogenic potency of the thalidomide (Thd) derivative phthalimidophthalimide (Phtpht) was assessed in the common marmoset (Callithrix jacchus), by oral administration of the relatively high daily dose of 50 mg Phtpht/kg body wt, during the susceptible period (days 48-61 of pregnancy). Since in this species daily doses of only 100 micrograms/kg body wt of the Thd derivative EM12 already induce typical gross structural abnormalities in nearly 100% of the fetuses, investigations with a small number of these New World monkeys allow a rough estimation of the teratogenic potency of Thd-type substances. Macroscopic inspection and skeletal evaluation of ten fetuses gave no indication of dysmorphogenesis following treatment with Phtpht. We conclude that Phtpht has little, if any, Thd-type teratogenic potency in this non-human primate.

Animals↗

PubMed1998

Pharmacologically evoked fictive motor patterns in the acutely spinalized marmoset monkey (Callithrix jacchus).

The existence of a spinal network capable of generating rhythmic alternating activity resembling locomotion still has not been firmly established in primates, including man, although evidence for one is accumulating. The present study investigated whether it is possible to activate such a network by administration of a variety of pharmacological agents to acutely spinalized marmoset monkeys (Callithrix jacchus) in the absence of phasic afferent input to the spinal cord. Fourteen marmoset monkeys were decerebrated, spinalized, and paralyzed. The nerves supplying both hindlimbs were cut and recorded from. In 5 monkeys the effect of electrical stimulation of the brainstem was investigated before spinalization. In 3 of these monkeys, rhythmic activity alternating between extensors and flexor nerves was seen. In the 2 other monkeys only synchronized activity was elicited. In acutely spinalized monkeys, administration of L-3,4-dihydroxyphenylalanine (L-dopa; 3-4 h after treatment with nialamide) failed to evoke any rhythmic alternating activity. In contrast, administration of clonidine elicited alternating activity in all of 8 monkeys tested. In 4 of these monkeys, the activity was restricted to alternation between ipsilateral and contralateral flexor nerves, whereas alternating activity between ipsilateral flexors and extensors was also seen in the other 4 monkeys. Administration of excitatory amino acids (NMDA or NMA) also elicited rhythmic alternating activity in 7 of 10 spinalized monkeys. In 4, rhythmic alternating activity was seen between extensors and flexors on one limb as well as between ipsilateral and contralateral flexors. In 3 monkeys NMDA/NMA produced alternation between extensors and flexors of one limb without alternation between the ipsilateral and contralateral sides. Administration of noradrenaline failed to elicit any rhythmic activity, but rather completely depressed already existing activity. Administration of serotonin (5-HT) was ineffective in facilitating alternating activity in 6 of 8 monkeys and was facilitatory to rhythmic activity in the other 2. We suggest that these data provide further evidence of a network capable of eliciting rhythmic alternating activity resembling locomotion in the primate spinal cord. The network, however, seems to be more difficult to activate pharmacologically in those conditions than in other mammals. This may especially be the case in higher primates, including man.

Animals↗

PubMed2006

Evolution of growth hormone in primates: the GH gene clusters of the New World monkeys marmoset (Callithrix jacchus) and white-fronted capuchin (Cebus albifrons).

The GH gene cluster in marmoset, Callithrix jacchus, comprises eight GH-like genes and pseudogenes and appears to have arisen as a consequence of gene duplications occurring independently of those leading to the human GH gene cluster. We report here the complete sequence of the marmoset GH gene locus, including the intergenic regions and 5' and 3' flanking sequence, and a study of the multiple GH-like genes of an additional New World monkey (NWM), the white-fronted capuchin, Cebus albifrons. The marmoset sequence includes 945 nucleotides (nt) of 5' flanking sequence and 1596 nt of 3' flanking sequence that are "unique"; between these are eight repeat units, including the eight GH genes/pseudogenes. The breakpoints between these repeats are very similar, indicating a regular pattern of gene duplication. These breakpoints do not correspond to those found in the much less regular human GH gene cluster. This and phylogenetic analysis of the repeat units within the marmoset gene cluster strongly support the independent origin of these gene clusters, and the idea that the episode of rapid evolution that occurred during GH evolution in primates preceded the gene duplications. The marmoset GH gene cluster also differs from that of human in having fewer and more evenly distributed Alu sequences (a single pair in each repeat unit) and a "P-element" upstream of every gene/pseudogene. In human there is no P-element upstream of the gene encoding pituitary GH, and these elements have been implicated in placental expression of the other genes of the cluster. The GH gene clusters in marmoset and capuchin appear to have arisen as the consequence of a single-gene duplication event, but in capuchin there was then a remarkable expansion of the GH locus, giving at least 40 GH-like genes and pseudogenes. Thus even among NWMs the GH gene cluster is very variable.

Alu Elements↗

PubMed2001

Characterization of the expressed immunoglobulin IGHV repertoire in the New World marmoset Callithrix jacchus.

The common marmoset (Callithrix jacchus jacchus) is a member of the Callithrichinae, a family of outbred New World primates with limited MHC polymorphisms and a propensity to develop spontaneous or experimentally induced autoimmunity. C. jacchus marmosets are susceptible to experimental allergic encephalomyelitis (EAE), and spontaneously develop autoimmune colitis and thyroiditis. Such disease models approximate the complexity of human autoimmune disorders, and allow an investigation of the respective roles of T-cell and antibody responses to self-antigens in outbred species. A key issue for further definition of the pathogenic antibody responses in human autoimmunity is to understand the diversity of the immunoglobulin repertoire in primate models. Here, we characterized the expressed immunoglobulin IGHV repertoire of the C. jacchus marmoset. Six IGHV subgroups were identified which show a high degree of sequence similarity to their human IGHV counterparts (IGHV1, IGHV3, IGHV4, IGHV5, IGHV6, and IGHV7). As in the expressed human IGHV repertoire, the framework regions are more conserved when compared to the complementarity-determining regions (CDRs), with the greatest degree of variability located in CDR3. Predicted structural features are highly conserved between C. jacchus and human IGHV. This information now provides a framework for studies of the antigen-specific repertoire of pathogenic antibodies in EAE and other immune-mediated diseases.

Amino Acid Sequence↗

PubMed2002

Amyloid-beta deposits in the cerebral cortex of the aged common marmoset (Callithrix jacchus): incidence and chemical composition.

The incidence, distribution and chemical composition of amyloid-beta (A beta) peptide-positive deposits were investigated in the lower primate species common marmoset (Callithrix jacchus). No A beta deposits were observed in the brains of 7 marmosets below 7 years of age. In 15 marmosets above 7 years, 60% displayed cortical A beta-immunoreactive plaques, 80% had A beta deposited in intracortical vessels and 87% displayed A beta deposits in meningeal vessels. The cerebral cortex of the oldest animal (15 years) contained a substantial density of deposits. A beta-immunoreactive plaques were found predominantly in association cortical zones followed by a lower density in paralimbic cortical areas. Deposits within vessels were most frequent in occipital cortex. A beta40 was found primarily in vascular deposits, while A beta42 was present in plaques. Approximately 20% of plaques and most vascular deposits displayed thioflavin S staining, indicative of the presence of fibrillar A beta. Varying proportions of A beta deposits contained acetylcholinesterase or butyrylcholinesterase activities and apolipoprotein E and alpha1-antichymotrypsin immunoreactivity. A few plaques contained immunoreactivity for amyloid precursor protein in swollen neurites. However, no abnormally phosphorylated tau immunoreactivity was present in these neurites. Survival analysis in a colony of marmosets indicated that only 6% of animals can be expected to survive beyond 7 years of age. These results indicate that the aged marmoset brain displays A beta deposits with a distribution and chemical composition similar to those found in the human. These similarities suggest that the aged marmoset may be a useful lower primate model for the study of the pathological effects of A beta. However, the relatively small number of animals which can be expected to reach old age severely limits the utility of this species as a model of A beta deposition.

Aging↗

PubMed2006

Can wild common marmosets (Callithrix jacchus) solve the parallel strings task?

Patterned string tasks are a test of perceptual capacity and the understanding of means-end connections. Primates can solve complex forms of this task in laboratories. However, this may not indicate the level of such cognition that is commonly employed in the wild, where decision-making time is often short and distractions such as predator avoidance and competition between conspecifics are often prevalent. The current study tests whether wild common marmosets (Callithrix jacchus) can successfully complete the simplest form of the patterned string task, parallel strings, while in their natural environment. Although 12 out of 13 marmosets could successfully complete the task, in previous laboratory-based studies on primates, the errors at this task by all primate species tested were consistently lower than in the present study. This is probably explained by the added difficulties imposed by the natural setting of the task in the present study, exemplified by a significant increase in observed vigilance behaviour by subject animals prior to attempts at the task that were unsuccessful. The undertaking of such tasks by common marmosets in situ probably provides a more reasonable representation of the levels of cognitive capacity expressed by this species in the wild than do laboratory-based studies of the task.

Animals↗

PubMed2006

Perception of the stereokinetic illusion by the common marmoset (Callithrix jacchus).

Stereokinetic illusions have never been investigated in non-human primates, nor in other mammalian species. These illusions consist in the perception of a 3D solid object when certain 2D stimuli are rotated slowly in the plane perpendicular to the line of sight. The ability to perceive the stereokinetic illusion was investigated in the common marmoset (Callithrix jacchus). Four adult marmosets were trained to discriminate between a solid cylinder and a solid cone for food reward. Once learning criterion was reached, the marmosets were tested in sets of eight probe trials in which the two solid objects used at training were replaced by two rotating 2D stimuli. Only one of these stimuli produced, at least to the human observer, the stereokinetic illusion corresponding to the solid object previously reinforced. At test, the general behaviour and the total time spent by the marmosets observing each stimulus were recorded. The subjects stayed longer near the stimulus producing the stereokinetic illusion corresponding to the solid object reinforced at training than they did near the illusion corresponding to the previously non-rewarded stimulus. Hence, the common marmosets behaved as if they could perceive stereokinetic illusions.

Animals↗

PubMed2006

Common marmosets (Callithrix jacchus) do not utilize social information in three simultaneous social foraging tasks.

Social foraging is suggested to increase foraging efficiency, as individuals might benefit from public information acquired by monitoring the foraging activities of other group members. We conducted a series experiments with captive common marmosets (Callithrix jacchus) to investigate to what extent marmosets utilize social information about food location when foraging simultaneously with conspecifics. Subjects were confronted with dominant and subordinate demonstrators in three experiments which differed in the amount of information about food location available to the demonstrators. In all three experiments, the focal subjects' performance in the social condition was not enhanced in comparison to a non-social control condition. Because we could rule out kleptoparasitism and aggressive displacements as explanations, we argue that the subjects' tendency for scramble competition by avoiding others and dispersing over the foraging area seems to inhibit or mask the acquisition of social information about the location of rewarded patches.

Animals↗

PubMed2004

Sex differences in common Marmosets (Callithrix jacchus) in response to an unfamiliar food task.

There is a growing body of information on sex differences in callitrichid behaviour that includes the animals' performance in food tasks. For example, both reproductive and non-reproductive adult females have been found to be more successful than adult males in solving food tasks. In this study ten adult male and ten adult female common marmosets (Callithrix jacchus), housed individually, were tested with an unfamiliar task that involved the extraction of an embedded food. The task was to open a plastic canister that contained a raisin; the open end was covered with parchment paper. Each marmoset was given 15 trials in three blocks of 5 consecutive days. We measured the latency for each animal to open the lid and get the raisin--by one of five strategies that spontaneously emerged. The females learned the task faster and more efficiently than males; all the females opened the canister on day 1, for instance, in contrast to seven of the males on the same day. Females also progressively decreased the time that they took to open the tube. The final latency on day 15, for instance, was significantly shorter for the females. These results are consistent with relevant literature for callitrichids and cannot be accounted for in terms of differences in mental abilities, strength, hand morphology, or energy requirements. Further investigation is necessary to clarify the reasons for these differences.

Animals↗

PubMed2004

Analysis of infant carrying in large, well-established family groups of captive marmosets (Callithrix jacchus).

To assess the pattern of infant carrying across time and family members, we counted which animals in 13 well-established family groups of captive-bred marmosets (Callithrix jacchus) carried neonates during the first 8 weeks of life. The neonates were carried almost continuously for the first 3 weeks and then spent progressively more time independently. The mother did most of the carrying for the first 2 weeks, her contribution rising from day 1 to day 3 and declining thereafter. The contribution of the father was high on day 1, declined during the first week, and then rose to a peak in the fourth week. The contribution of the siblings rose sharply during the first week and declined thereafter. There was no overall difference in amount of infant carrying by each parent. The contribution of each sibling was small although in these large families the total contribution by siblings was large. These data may differ from previous observations because the breeding pairs were very well established, the families were large, and all except the youngest animals were very experienced in rearing and carrying. These data emphasise the group-dynamic nature of infant carrying in a primate species.

Animals↗