Serum biochemical, hematological and body measurement data for common marmosets (Callithrix jacchus jacchus)

Blood samples were drawn and body measurements taken from healthy adult and juvenile common marmosets which had been housed under controlled environmental conditions for a minimum of 2 years. Blood was analyzed for serum biochemical and hematological constituents.     

Neonatal behavioral scoring of common marmosets (Callithrix jacchus): relation to physical condition and survival

A seven-task behavioral test was performed on 86 common marmoset (Callithrix jacchus) infants, 24-36 h following birth. This report describes the test outcome and its relation to physical condition and survival of the infants. The percentage of infants receiving a perfect score on a given task ranged from 30.6 (rooting) to 70.6% (grasping). Heavier infants were more likely to have perfect scores for crawling (F=4.20, P=0.044) and infants with a longer knee-heel length tended to be more likely to have a perfect grasping score (F=3.63, P=0.06). While the modal score was a perfect score for most individual tasks, the modal number of total perfect scores that a given infant received was 3-4 and only 4.7% of infants received perfect scores on all seven tasks. These results suggest that this group of behavioral tasks will produce a variable response within a population of neonates. While no individual behavioral score predicted survival during week 1, the number of perfect scores across all tasks was predictive of survival outcome; infants with a higher total number of perfect scores were more likely to survive (F=6.02, P=0.018). When all combinations of tests were compared, the best predictor of survival was outcome on four of the seven tests, all related to motor skills (F=7.46, P=0.009).     

Congenitally caused fused labia in the common marmoset (Callithrix jacchus)

In this paper, the occurrence of an external genital abnormality in female marmoset monkeys (fused labia) is discussed. This malformation was detected, for the first time, in a group of animals at the German Primate Center (GPC), Goettingen. The malformed vulva was completely sealed except for an opening of 1.5-2.5 mm around the urethra sufficient for urination. Because of this defect the animals were not able to copulate. As a consequence, the affected females were functionally infertile although they had a normal genital tract and a regular cycle. This vulvar abnormality was found in 12 females, offspring of 10 pairs in which either one or both came to the German Primate Center from two genetically related colonies in Munich, Germany, and one colony in Basel, Switzerland. The abnormality appeared to be recessive and inheritable from either parent. In pairs in which both animals were from one of the mentioned colonies, 45% of the female offspring were affected. In pairs where only one partner came from these colonies, 26% of female offspring had the malformation. These results indicate that avoidance of inbreeding, which is frequently performed in primate colonies, may reduce, but not eliminate the expression of abnormalities of genetic origin. Therefore selective breeding is required, and, in colonies where these recessive mutations are widespread, the development of genetic screening tests would be advantageous.     

Long-term study of infant-carrying behavior in captive common marmosets (Callithrix jacchus): Effect of nonreproductive helpers on the parents' carrying performance

Infant-carrying behavior in four families ofCallithrix jacchus was investigated over a period covering six to eight litters. We evaluated the effect of the total number of helpers and the number of adult helpers on the parents' carrying performance for the total carrying period and for three age stages of the infants. The carrying performance of the parents reached an asymptote beginning with litters 3 to 5. In two groups, the carrying performance of the parents was significantly negatively correlated with group size. However, considerable differences existed within each group and between the groups. The mother was the primary caregiver in the early weeks of the infants' lives. In this phase the helpers' contribution to carrying was less than might be expected. The relief of the parents from infant-carrying was greatest when the infants were 4 to 7 weeks old. Breeding males benefited most and from every helper, while breeding females benefited most from adult helpers, i.e., the carrying performance of the breeding female was considerably reduced until the respective group had grown to 8 to 10 members (infants not included). This group size is considered to be ideal for maximal relief of the parents from infant carrying. An increasing number of adult nonreproductive helpers (>4 or 5) does not induce a further reduction of the parents' carrying performance. Infant-rearing experience of nonreproductive helpers seems to be more important for the parents' and, especially, the breeding female's relief from infant-carrying than the overall number of helpers is. The data also strongly evidence that a group member's participation in infant-carrying is influenced by housing conditions and the demographic history of the group.     

Hormonal changes related to paternal and alloparental care in common marmosets (Callithrix jacchus)

The physiological mechanisms of parental and alloparental care in cooperatively breeding nonhuman primate species such as the common marmoset (Callithrix jacchus) are poorly known. In this study, we examined prolactin and cortisol plasma levels of fathers and older offspring of both sexes, with and without previous experience in infant carrying, around parturition and during infant carrying. Blood samples were collected from fathers and older offspring and prolactin and cortisol were measured by RIA and EIA, respectively. Prolactin levels of both caretakers were not influenced by infant's birth, previous experience or proximity to parturition. However, prolactin levels increased in both caretakers while in physical contact with infants and also with the number of infants being carried in older offspring. These findings suggest that increased prolactin seems to be mainly due to physical effort rather than a physiological trigger of paternal and alloparental care in common marmosets. Cortisol levels were higher for experienced fathers shortly before parturition which could act to reinforce affiliative bonds between breeding males and females at this time or in the ability of males to detect the proximity of the parturition or both.     

An experimental analysis of social interaction in the common marmoset (Callithrix jacchus jacchus)

Adult and juvenile common marmosets were introduced to unfamiliar conspecifics individually and in whole groups. In introductions using animals of the same sex, adults were mutually hostile unless they were related or socially familiar; juveniles behaved submissively to adults and little aggression was observed between juveniles. In introductions using animals of the opposite sex, males of all ages solicited females but females did not reciprocate. When whole groups were introduced, in two experiments most of the elder group members behaved aggressively and younger animals did not interact frequently; but in a third experiment, in which the adult males were related, little aggression was observed and younger animals behaved amicably. It is argued that the behavioral reactions shown by individual marmosets are related to territorial hostility and that the behavior of juveniles to adults may aid assimilation of younger animals into new groups.     

Parent-daughter relationships and social controls on fertility in female common marmosets,Callithrix jacchus

This study examined the reproductive status of mothers and daughters to determine if parent-eldest daughter interactions would influence the daughter's fertility in the cooperatively breeding common marmoset, Callithrix jacchus. Twice weekly fecal samples were collected for hormonal analyses from seven daughters and their mothers and analyzed for cortisol, estradiol, and progesterone by EIA. Behavioral data were collected three times weekly while the daughters were under three conditions: natal family, after removing from the family and paring with a novel male, and after removing from the paired condition and placed back with the family (renatal). Under the natal condition, five of the seven daughters exhibited ovarian cycles while their mother was pregnant or displaying ovarian cycling. The five cycling daughters spent significantly more time initiating affilative behaviors with their mothers than with their fathers and showed significant changes in their behavior over the length of the ovarian cycle. However, aggression, submission, and sexual behaviors were very low for daughters in the natal phase. No differences between cortisol levels were found for a daughter and her mother. Cortisol levels showed a significant and sustained increase upon pairing within the first 20 days. All females but one cycled while paired. Six of the seven females were accepted back into the family after pairing and five of the seven females were ovulating. These results suggest that marmoset daughters are not necessarily reproductively suppressed while living with the family. Additionally, these data suggest that female marmosets that leave their family to explore mating opportunities with other groups may return to their family without reproductive or aggressive consequences.     

Home-range size and use and territorial behavior in the common marmoset,Callithrix jacchus jacchus,at the tapacura field station,recife, Brazil

Data were obtained both from observation and by radiolocation on the size and use of the home range of the common marmoset, Callithrix jacchus jacchus.Ranges were small compared to those of other callitrichids, varying between 0.72 to 1.62 ha, and a high proportion of the home range was used each day. The marmosets showed territorial behavior, defending an area almost equivalent to the home range. Despite this, mating between animals belonging to neighboring groups was seen. Correlations between the use of the home range and some environmental variables showed little consistency between two groups which occupied ranges of differing resource density, and their activity patterns, as measured by movement through their ranges, were also different. Possible reasons for these inconsistencies are discussed.     

Helicobacter callitrichis sp. nov., a novel Helicobacter species isolated from the feces of the common marmoset (Callithrix jacchus)

A slowly growing microaerophilic Helicobacter species was isolated from the feces of the common marmoset (Callithrix jacchus). This bacterium possessed a pair of nonsheathed bipolar flagella, was positive for oxidase, catalase and alkaline phosphatase activities, but was negative for gamma-glutamyltranspeptidase and urease activity and for nitrate reduction. The bacterium was susceptible to nalidixic acid and resistant to cephalotine and did not hydrolyze hippurate. On the basis of phenotypic characteristics, 16S rRNA gene sequence analysis and whole-cell protein profiles, the isolate represents a new species of the genus Helicobacter, for which the name Helicobacter callitrichis sp. nov. is proposed; the type strain of the new species is R-204(T) (GenBank accession number AY192526).     

Exposure to infant scent lowers serum testosterone in father common marmosets (Callithrix jacchus)

Common marmoset (Callithrix jacchus) males are bi-parental non-human primates that show extensive paternal behaviour. Fathers are in direct sensory contact with their infants during the natal period. We found that fathers exposed to isolated scents of their infant displayed a significant drop in serum testosterone levels within 20min after exposure, whereas parentally naive males did not. These data suggest that infant's scent may have a causal role in regulating paternal testosterone in their fathers. This is the first study to demonstrate that olfactory cues have an acute effect on paternal care.     

Rapid diagnosis and management of parainfluenza I virus infection in common marmosets (Callithrix jacchus)

During 1983 a severe episode of respiratory infection occurred in a marmoset colony at these laboratories. Of 91 marmosets, 69 showed clinical signs of disease, one died and nine were so ill that euthanasia was necessary. Eight were examined post mortem and all showed consolidation of the lungs. Laboratory studies were carried out in an attempt to establish the cause of the outbreak and an interstitial pneumonia was found in seven animals which were examined histologically. Direct electron microscopy of nasal swabs and lung samples revealed the presence of a high titre of a paramyxovirus, and subsequent immunofluorescence studies established that the particular paramyxovirus involved was parainfluenza virus type I. Subsequent studies showed that surviving affected animals had seroconverted to parainfluenza I virus while animals that had not been implicated in the outbreak had not.     

Exploratory behavior and learning in laboratory marmosets (Callithrix jacchus jacchus): Comparisons between experimental-cage and home-cage activity

In this paper I examine exploratory behavior and learning in two groups of common marmosets (Callithrix jacchus jacchus), both living under laboratory conditions. The main aim of my studies was to compare behavior occurring in an experimental testing situation with home-cage behavior, and to assess conditions under which exploration is enhanced. One group of marmosets was tested individually in an experimental room away from a larger animal holding room, and a second group was observed in their own home cages, surrounded by other marmosets. Marmosets in both groups were given the opportunity to learn simple tasks, such as pressing a lever for food or jumping on to a wire grid to open a door and see a neighbouring marmoset, and were provided with sets of novel or familiar objects to encourage play and exploration. In the isolated experimental cage, marmosets which learnt a lever-pressing task showed higher general activity levels than controls; in the home cages the mere addition of novel objects resulted in enhancements in exploratory behavior (measured in terms of contacts with the objects). Although the activities associated with learning tended to decline over time, the novel objects remained a constant interest throughout the experiment. The results have implications for maintaining marmosets in captivity, especially in situations when they are housed separately.     

Differential infant carrying in captive and wild common marmosets (Callithrix jacchus)

Callitrichids are communal breeders that lack sexual dimorphism, and only a few studies have examined behavioral gender differences among them. The purpose of this study was to investigate gender differences in infant carrying in 16 captive and seven wild common marmoset groups. Our results showed that female–female twin pairs were carried significantly more often by fathers than were male–male and male–female pairs both in the wild and in captivity. We suggest these differences may be related to different reproductive potentials of male and female Callithrix jacchus and possibly to future breeding competition among females.     

Hematologic and immunologic responses in common marmosets (Callithrix jacchus) infected with Plasmodium knowlesi and Epstein-Barr virus

The hematologic and immunologic responses to infection with either the Epstein-Barr virus alone or infection with Epstein-Barr virus and Plasmodium knowlesi were studied using common marmosets (Callithrix jacchus). The assays performed included complete blood cell counts, determinations of natural killer cell activity, and determinations of antibody titers to Epstein-Barr virus early antigen, virus capsid antigen and the nuclear antigen. While no animal showed signs of lymphoproliferative disease, it was found that animals infected with Epstein-Barr virus became positive for early antigen, virus capsid antigen and nuclear antigen at low levels. No difference in antibody titers between Epstein-Barr virus infected animals and co-infected animals was observed. An increase also was found in the number of leukocytes in all groups, and an increase in natural killer cells following infection with Epstein-Barr virus. Some depression in natural killer cells was observed in the co-infected animals when compared to Epstein-Barr virus infected animals.     

Suppression of prolactin does not reduce infant care by parentally experienced male common marmosets (Callithrix jacchus)

High levels of prolactin have been found to correlate with the expression of paternal care in a variety of taxa. However, in mammals, there is little experimental evidence that prolactin is causally involved in the stimulation or maintenance of paternal care. Here, we suppressed prolactin production in paternally experienced common marmoset fathers in their family groups during the first 2 weeks after their infants were born. Circulating prolactin levels were suppressed using cabergoline (Dostinex: Pfizer), a long acting dopamine (D2) agonist with minimal behavioural side-effects. A within-subject design was used to compare behavioural and hormonal data on 5 paternally experienced fathers during two consecutive births. Cabergoline reduced prolactin to negligible levels in all fathers without effecting testosterone, DHT and cortisol and without adverse side-effects. However, lowering prolactin had no significant effect on the expression of majority of the behaviour patterns associated with paternal care. These included infant carrying, infant grooming and the frequency with which fathers retrieved and rejected infants. The only infant-related behaviour to be affected was the frequency with which fathers touched, licked and investigated infants. We noted a marginally significant increase in this behaviour during cabergoline treatment. Despite the lack of effect on paternal care, cabergoline did exert an effect on the affiliative/sexual behaviour of fathers as there was a significant increase in the grooming behaviour fathers directed at and received from their mates during drug treatment. This study showed that experienced male marmosets can express paternal behaviour in the absence of the high prolactin levels normally seen after infants are born.     

Bromocriptine administration lowers serum prolactin and disrupts parental responsiveness in common marmosets (Callithrix j. jacchus)

The influence of prolactin on parental responsiveness was investigated in eight unpaired, parentally inexperienced common marmosets (Callithrix jacchus; 6 female, 2 male). The marmosets were prescreened with infants (1-10 days of age) and required to exhibit short latency retrieval and infant carrying in at least three consecutive pretests as criterion for inclusion in this study. The marmosets were then administered the dopamine agonist bromocriptine (0.5 mg/0.5ml vehicle subcutaneously) and the vehicle alone (0.5 ml 10% ethanol solution) twice daily for 3 consecutive days in random order. Bromocriptine treatment reduced circulating prolactin to nondetectable levels. Bromocriptine treatment eliminated infant retrieval in four of the eight marmosets and was associated with significantly increased retrieval latencies and significantly reduced carrying durations in the four monkeys that continued to retrieve following bromocriptine treatment. When given the vehicle alone, the marmosets retrieved infants significantly faster than during pretests, suggesting a handling effect of the injection series. Bromocriptine treatments were associated with significantly increased movement during the tests. The results of this study indicate that prolactin and/or its regulatory neurotransmitters are involved in the control of the spontaneous display of parental responsiveness in common marmosets.     

Dissociation between seeing and acting: insights from common marmosets (Callithrix jacchus)

Perception-based measures often reveal much earlier competencies than action-based approaches. We explored this phenomenon generally labeled as “knowledge dissociation” in 28 common marmoset monkeys (Callithrix jacchus) using a paradigm where subjects had to localize a food item dropped down an opaque tube. Experiments 1 and 2 assessed common marmoset monkeys’ gravity bias in an action based version of the tubes task. Experiments 3 and 4 investigated whether marmosets’ performance increases in an action-free task context where they simply look at objects falling down a tube. The results suggest that common marmosets have some intuition of continuity/solidity constraints when tested with perception based measures even though these principles do not appear to guide their search for falling objects.     

Urine collection in the common marmoset (Callithrix jacchus) and its applicability to endocrinological studies

We investigated a new method of urine collection in the common marmoset. We entered the cage as soon as the light cycle started in the breeding room and collected urine from the animal directly without any restraint. We were able to take separate samples from completely different individuals housed together for behavioral studies in the same cage. Urine and blood samples were taken from individuals from late pregnancy through postpartum nursing period. Cortisol and prolactin concentrations measured in urine were compared to those measured in blood to evaluate this collection method. LH/CG level in the urine samples was also measured. Urine data in females indicated a tendency toward high cortisol values during late pregnancy, a sharp drop before parturition, and increase after delivery. In females cortisol levels measured in blood closely resembled concentrations measured in urine. Urine cortisol in males clearly indicated an increase postpartum, but the increase was not indicated in plasma. Plasma and urine prolactin concentrations in females made a similar increase during lactation. Male's plasma prolactin clearly indicated an increase directly proportional to strong behavioral contact with the infant. We also confirmed hormonal changes during pregnancy, and postpartum ovulation and subsequent pregnancies, from urine LH/CG data. We found this method extremely useful because of the high correlation between cortisol, prolactin and LH/CG data from blood and urine. Additionally, we collected urine samples with little stress to the animal from fear, irritation, pain, etc.     

Sex differences in food acquisition and aggression in captive common marmosets (Callithrix jacchus)

Competition for food within the social group has been postulated as an important factor affecting primate social organization. This study examined how factors such as sex, aggression, dispersion of food, and amount of difficulty involved in obtaining food affect the distribution of food in common marmoset (Callithrix jacchus) social groups. Mated pairs of adultC. jacchus were presented with food that was either dispersed or concentrated, and either difficult or easy, to obtain. The number of food pieces obtained, aggressive displays, incidents of physical aggression, and amount of time spent searching for food were recorded for each animal. Neither dispersion nor difficulty in obtaining food had significant effects on the distribution of food or any of the other behaviors examined. The primary factors affecting food distribution were aggression and amount of time spent searching. Females obtained more food than males in all situations because they were more aggressive and apparently more motivated to search for food than were males.