Histochemical observations on the taste buds of the marmosets (Callithrix jacchus and Callithrix penicillata).

The epithelial cells in the taste buds of C. jacchus and C. penicillata show a moderate amount of ribonucleic acid an a concentration of a PAS-positive diastase-resistant material at their apical part. These cells are devoid of UDPG-GT, phosphorylases, G-6-PA, alanyl aminopeptidase, leucine aminopeptidase, cholinesterase and MAO; they present a weak reaction of F-1, 6-P Ald, LDH, SDH, MDH, cytochrome oxidase, beta-OHBDH, nonspecific esterase and acid phosphatase and a stronger reaction to ADH, NADPH2-TR, ATPases, alpha-GPDH, alkaline phosphatase, 5-nucleotidase and GDH. Although some enzymes (alkaline phosphatase, 5-nucleotidase and ATPases) have an almost uniform reactivity by the several taste buds, the other ones react with a lesser intensity in the smaller uniform reactivity by the several taste buds, the other ones react with a lesser intensity in the smaller taste buds of the fungiform papillae. As a rule the apical part of the cells shows a stronger enzymatic reactivity. The taste buds of the marmosets are penetrated by acetylcholinesterase positive nerve fibers whereas the autonomic ganglia in the connective tissue contain both-acetyl and butyrylcholinesterase.     

Histochemical studies on the adrenal glands of the marmosets (Callithrix jacchus and Callithrix penicillata).

The histrochemistry of the adrenal glands was studied in four adult male marmosets (two Callithrix jacchus and two Callithrix penicillata). It was impossible to demonstrate any reactivity to UDPG-GT, ADH, alanyl aminopeptidase, leucine aminopeptidase, xilitol (NAD-dependent) dehydrogenase, beta-glucuronidase and aryl-sulfatase in these glands. Total phosphorylase was found in scattered cells of the glomerulosa and adjacent outer fasciculata of one C. penicillata. The dehydrogenases (LDH, G-6-PDH,6-PGDH, NADPH2-TR,ICDH,SDH,NADH2-TR, alpha-GPDH, beta-OHBDH) as well as the hydrolases (except alkaline phosphatase, ATPase, and acetylcholinesterase) showed a stonger reactivity in the cortical part. Some hydrolases (naphthol acetate esterase, acid phosphatase) and cytochrome oxidase were less reactive in the zona glomerulosa, where the dehydrogenases were more abundant. The outer fasciculata and the reticularis also showed a strong dehydrogenase reactivity.     

Histochemical studies on the submandibular ganglia of marmosets (Callithrix jacchus and Callithrix penecillata).

The histochemistry of the neural cells was studied in the submandibular ganglia of 5 Callithrix jacchus (3 males and 2 females) and 4 Callithrix penicillata (2 males and 2 females). These cells contain neutral mucopolysaccharides, nucleoproteins and lipidic materia, but are apparently devoid of glycogen. It is impossible to demonstrate in them any reactivity for UDPG-GT, phosphorylases, ATPase at pH 6.3, leucine aminopeptidase and alanyl aminopeptidas. The reaction for the other searched enzymes was as follows: weak (F-1,6-P Ald and cytochrome oxidase), weak to moderate (ADH, 6-P-GDH, ICDH, SDH, MDH, alpha-GPDH and beta-OHBDH), moderate (G-6-PDH, F-1,6-PA, LDH and GDH), moderate to strong (ATPase at pH 7.4, nonspecific esterase and acid phosphatase) and strong (G-6-PA, NADH2,-TR, NADPH2-TR, ATPase at pH 8.5 and 9.4 and alkaline phosphatase).     

Cross-fostering between two species of marmosets (Callithrix jacchus) and Callithrix penicillata)

Cross-fostering technique can be defined as adoption of infants by adults of other species. This phenomenon is poorly investigated because very young animals have few opportunities to interact peacefully with non-conspecific adults, either in captivity or in natural conditions. This study describes the induction of cross-fostering in captivity between white tufted-ear (Callithrix jacchus) and black tufted-ear marmosets (Callithrix penicillata). We conclude that this technique can be very useful for preserving the life of rejected by parents or orphan infants, mainly in the case of species with low reproduction rate in captivity or those threatened by extinction, as well for investigating the environmental effects on the typical behavior of species (courtship, food preference, vocalization patterns, e.g.).     

Post-conflict affiliation in common marmosets (Callithrix jacchus jacchus)

Post-conflict (PC) affiliation has been demonstrated in a number of Old World monkeys and apes, but very little is known about the occurrence of the phenomenon in New World monkeys. This study examined 282 PC interactions after spontaneous conflicts around feeding time in two family groups (N = 12) of captive common marmosets, Callithrix jacchus jacchus. We found an overall corrected conciliatory tendency of 31%. Selective attraction was seen: former opponents met significantly more often in PCs than in matched controls (MCs) (27% and 16%, respectively). There was no difference in the occurrence of PC affiliation between dyads consisting of parent-offspring constellations compared to offspring-offspring constellations. PC affiliative behaviors were seen in the first three minutes following conflict termination, and consisted mainly of proximity, play invitations, and food transfer. Notably, former opponents remained within arm's reach after 17% of conflicts. Affiliation was more likely to follow after conflicts involving play issues. The functional importance of the PC affiliation in marmosets remains to be examined.     

Hematology of common marmosets (Callithrix jacchus)

The hematology of the common marmoset (Callithrix jacchus) was investigated to provide reference values for the normal animal. Red blood cell counts, white blood cell counts, hemoglobins, mean cell volumes and differential white blood cell mean values were determined for Texas A&M colony-born animals and those obtained from the wild. The analyses were completed on 31 animals, three times each, for a total of 93 analyses, which included 16 colony-born and 15 wild-born marmosets. The hematological mean values found for marmosets were similar to those mean values reported for humans. The ranges for the hematology values were much narrower in the colony-born marmosets, and the average white blood cell count was significantly lower in these animals. This indicated that it is possible to produce and maintain a more uniform animal in the colony environment and, consequently, these animals are more suitable than wild-born animals for use as models for human research.     

Histochemical data on the liver of the marmoset (Callithrix jacchus).

The histochemistry of the hepatic parenchymal cells was studied in four Callithrix jacchus. A large amount of glycogen was noted throughout the lobules while the UDPG-GT and the phosphorylases were found unevenly distributed by the hepatic strands with different degrees of reactivity. Near the central vein one of the livers showed PAS-positive nuclear corpuscles that were more conspicuous in the hepatic cells with a larger amount of cytoplasmic glycogen and weaker UDPG-GT and phosphorylase reactivities. G-6PA (in a larger amount) and LDH (in a moderate amount) were found evenly distributed in the hepatic strands. F-1-6PA was seen sometimes with a stronger reactivity at the peripheral part of the lobules. The enzymes of the pentose shunt (G-6PDH, 6-PGDH and NADPH-2-TR) reacted strongly and as a rule evenly distributed near the hepatic lobules. Occasionally they reacted more intensely in the row of hepatic cells disposed just around the central vein. Cytochrome oxidase showed a very faint reaction. Cis-aconitase and ICDH were weak or moderate. NADH-2-TR more than SDH more than MDH were seen frequently diffused near the hepatic strands. SDH and MDH in some instances showed a stronger reactivity in the row or group of hepatic cells around the central vein. ATPase at pH 6.3 was negative in the marmoset liver; ATPase at pH 7.4 was mainly found in the wall of the portal area vessels; ATPase at pH 8.5 showed a stronger reactivity in the cytoplasm of the hepatic cells and ATPase at pH 9.4 was more abundant in the bile capillaries. The reactivity of the lipid metabolism enzymes was moderate with regard to alpha-GPDH or negligible with regard to beta-OHBDH. Acid phosphatase showed a stronger reaction, but almost limited to the Kupffer cells. The hepatic cells showed only a moderate amount of RNA. Some enzymes of the protein metabolism, such as GDH and leucine aminopeptidase showed a stronger reactivity while some others, such as alanyl aminopeptidase and MAO, were seen diffused near the hepatic lobules in a small amount. Enzymes of the mucopolysaccharide metabolism were not found at all (beta-glucuronidase) or showed only a weak reactivity, such as xylitol dehydrogenase.     

Effects of male partners upon proceptivity in ovariectomized estradiol-treated marmosets (Callithrix jacchus)

Effects of male partners upon the expression of female proceptivity were examined in two experiments using 16 ovariectomized marmosets. Experiment 1 showed that the female's proceptive tongue-flicking display (PTF) is triggered specifically by eye contact with the male. Stimulation of PTF by administration of estradiol-17 beta (E2) to ovariectomized females depends in part upon the male's responsiveness to female displays, such as "staring" and "freezing," which may serve to attract his attention and to establish eye contact. Experiment 2 provided evidence that females' proceptivity decreases if their male partners are lesioned in the preoptic area/anterior hypothalamus. Such males are sexually hypoactive and less responsive to the females' visual displays. However, E2 still activates PTF if females succeed in initiating eye contact with males. Results indicate that variability in effects of E2 upon proceptivity in marmosets may be influenced by subtle aspects of facial communication between the sexes as well as by individual differences in hormonal sensitivity. Copulatory activity in males is not essential for E2 to exert its stimulatory action upon proceptivity in female marmosets.     

Reproduction in captive common marmosets (Callithrix jacchus)

Though sexual maturation may begin at around one year of age, first successful reproduction of the common marmoset (Callithrix jacchus) is likely to be later, and it is generally recommended that animals not be mated before 1.5 years of age. The average gestation period is estimated to be 143 to 144 days. A crown-rump length measurement taken by use of ultrasonography during the linear, rapid, prenatal growth phase (between approx. days 60 and 95) can be compared against standard growth curves to estimate delivery date to within 3 to 4 days, on average. Marmosets produce more young per delivery than does any other anthropoid primate, and have more variation in litter size. Many long-established colonies report that triplets are the most common litter size, and there is documented association between higher maternal body weight and higher ovulation numbers. Higher litter sizes generally do not generate higher numbers of viable young. Marmosets are unusual among primates in having a postpartum ovulation that typically results in conception and successful delivery; reported median inter-birth intervals range from 154 to 162 days. However, pregnancy losses are quite common; one study of a large breeding colony indicated 50 percent loss between conception and term delivery. The average life span for breeding females is around six years; the range of reported average lifetime number of litters for a breeding pair is 3.45 to 4.0. Our purpose is to provide an overview of reproduction in the common marmoset, including basic reproductive life history, lactation and weaning, social housing requirements, and common problems encountered in the captive breeding of this species. A brief comparison between marmoset and tamarin reproduction also will be provided.     

Lymphocyte populations of Callithrix jacchus marmosets.

A lymphocyte population of common marmosets (Callithrix jacchus) was identified by rosette formation with African green monkey erythrocytes; the rosette-forming cells appeared to be T lymphocytes, as approximately 62% of circulating lymphocytes and 85% of thymus cells formed rosettes with African green monkey erythrocytes. In addition, common marmoset lymphoid cells carrying T-lymphotropic Herpesvirus saimiri or Herpesvirus ateles formed rosettes with African green monkey erythrocytes and treatment of common marmoset circulating lymphocytes with an anti-T cell serum and complement (C′) eliminated rosette-forming cells. Common marmoset T lymphocytes apparently carry a surface receptor for African green monkey erythrocytes, but unlike humans and other closely related nonhuman primates, T lymphocytes of common marmosets fail to form rosettes with sheep erythrocytes.     

Individual olfactory signatures in common marmosets (Callithrix jacchus)

Individual discrimination is likely a prerequisite for most primate social interactions. Olfactory cues are one set of stimuli used by primates to discriminate between individuals. Despite the importance of these olfactory signatures, there is little published research assessing the existence or function of individually unique odors among primates. This review systematically assesses behavioral and biochemical aspects of individual odors in a New World primate, the common marmoset (Callithrix jacchus). There are three objectives to this review: First, behavioral evidence for odors unique to the individual is evaluated in the context of results demonstrating that marmosets are able to discriminate between the scents from a familiar and a novel individual conspecific in behavioral bioassays under a variety of conditions. Second, biochemical evidence for individual scent signatures is debated with reference to studies examining qualitative and quantitative differences between the chemical compositions of scent-mark pools from adult females. A combined gas chromatography (GC) and mass spectrometry (MS) analysis demonstrated that each female had a unique ratio of highly volatile chemicals in the scent mark that could affect individual discrimination. Finally, the possible adaptive significance of individual odors in marmosets is debated. Individual odors may play a key role in regulating both female intrasexual competition and intersexual communication by providing a basis for the assessment of individual quality.     

Characteristics of the circadian activity rhythm in common marmosets (Callithrix j. jacchus)

The circadian activity rhythm of the common marmoset, Callithrix j. jacchus was investigated by long-term recording of the locomotor activity of 15 individuals (5 males, 10 females) from 1.5 to 8 years old, both under constant illumination and under LD 12:12. The mean period of the spontaneous circadian rhythm was 23.2 ± 0.3 h. Neither sex-specific differences nor a systematic influence of light intensity on the spontaneous period were observed, but the period was dependent on the duration of the trial and on the age of the individual. Due to the short spontaneous period, in LD 12:12 there was a distinct advance of the activity phase with respect to the light time and a masking of the true onset of activity by the inhibitory direct effect of low light intensity during the dark time. After an 8 h delay shift of the LD 12:12, re-entrainment of the circadian activity rhythm required an average of 6.8 ± 0.7 days; the average re-entrainment time after an 8 h phase advance of the LD cycle was 8.6 ± 1.3 day. This directional effect is ascribed to characteristics of the phase-response curve. No ultradian components were observed, either in the LD-entrained or the free-running circadian activity rhythm.     

Pregnancy diagnosis in the common marmoset (Callithrix jacchus jacchus).

Abdominal palpation of the uterus was carried out on 25 pregnant and 29 non-pregnant marmosets (Callithrix jacchus jacchus). 195 complete 24-hour urine specimens, collected between the first week of gestation and term (21 weeks), were tested with the Sub-Human Primate Tube (SHPT) test. No significant differences between the two methods in their ability to diagnose pregnancy were obtained between the first and 13th week of gestation. The SHPT test was seldom positive after the 13th week of pregnancy, whereas, with one exception, palpation always indicated pregnancy.     

Sexual behavior and extragroup copulations in a wild population of common marmosets (Callithrix jacchus).

Sexual behavior and mating patterns are described for 3 free-ranging groups of common marmosets living in a coastal forest in northeastern Brazil. Each group contained 2 breeding females. Within groups, sexual behavior was generally restricted to breeding females and a single behaviorally dominant male. Of 101 mounts and copulations, 24 involved pairings of individuals from 2 different groups. Extragroup sexual behavior was performed by both breeding and nonbreeding group members, and 65% of all adults mounted or copulated with an extragroup individual at least once. Sexual behavior occurred throughout the female reproductive cycle but was significantly more frequent during an 11-day 'conception period'. Thus, while female marmosets show no physical signs of estrus, both males and females likely do have some information about the timing of ovulation. Mating patterns in this population included both polygyny and monogamy and varied between groups and over time.     

Blood vitamin values of common marmosets (Callithrix jacchus)

The blood vitamin analyses of the common marmoset (Callithrix jacchus) were determined to provide baseline reference values for the normal animal. Ascorbic acid, riboflavin (erythrocyte glutathione reductase) [ECR], measurement, thiamin (erythrocyte transketolase) measurement and vitamin A (retinol) were determined for Texas A&M colony-born animals and those obtained from the wild. The analyses were completed on the animals, three times each, for a total of 93 analyses, which included 51 colony-born and 60 wild-born marmosets. A mean value of 0.98 mg/dl for ascorbic acid was found for the colony with a range from 0.06 to 4.1 mg/dl. The normal range for the marmosets appeared to be 0.5 to 1.5 mg/dl. The mean activity coefficient (AC) for the marmosets was 1.0 indicating that the animals had adequate riboflavin in the diet. The mean transketolase activities were (ribose remaining ?30.1 IU/L) and (sedoheptulose appearance ?7.9 IU/L). The mean and range for serum vitamin A (retinol) were 20.4 mg/dl and 6.96–57.44 mg/dl, respectively. None of the animals (colony-born or wild-born) exhibited any clinical signs of vitamin deficiencies as a result of being maintained in an indoor-outdoor environment over a three-year period.     

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.     

Do newborn vocalizations affect the behavioral and hormonal responses of nonreproductive male common marmosets (Callithrix jacchus)?

Parental care in mammals is influenced by sensory stimuli from infants, such as sight and sound, and by changes in the hormone levels of caretakers. To determine the responsiveness of common marmoset (Callithrix jacchus) adult males with and without previous experience in caretaking to newborn sensory cues, we exposed twelve males to infant vocalization recordings and assessed their hormonal and behavioral responses. Males were placed in the testing cage for 10 min under two conditions: (a) control condition (exposure to adult conspecific vocalization recordings), and (b) experimental condition (exposure to infant vocalization recordings). We recorded the frequency of approach towards the sound source, the time spent near it and locomotion frequency of males in the cage under both conditions. Blood samples were collected after each test for cortisol, measured by the enzyme immunoassay method. Infant vocalization affects the behavioral and hormonal responses of non-reproductive male common marmosets. All males approached and spent more time near the sound source and showed an increase in locomotion during infant vocalization exposure compared to the control condition. Successive exposure to infant vocalization increased the responsiveness in inexperienced males. Cortisol levels were significantly higher following infant vocalization exposure compared to the control condition. These findings support the assumption that sound stimuli from the newborn are critical in initiating and maintaining caretaker responsiveness and that cortisol seems to be important for alertness to sensory stimuli, modulating their motivation to interact with infants.