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PubMed2007

On the time scale of New World primate diversification.

New World primates comprise a diverse group of neotropical mammals that suddenly appeared in the Late Oligocene deposits of South America at around 26 million years ago (MYA). Platyrrhines seem to have separated from Old World anthropoids ca. 35 MYA, and their subsequent diversfication is not well documented in the fossil record. Therefore, molecular clock studies were conducted to unveil the temporal scenario for the evolution of the group. In this study, divergence times of all splits within platyrrhines until the generic level were investigated, using two different gene data sets under relaxed molecular clocks. Special attention was paid to the basal diversification of living platyrrhines and to the basal split of the modern Cebidae family, since these nodes were reported to be phylogenetically difficult to resolve. The results showed that analyses from various genomic regions are similar to estimates obtained by early single-gene studies. Living New World primates are descendants of ancestors that lived in the Early Miocene, at around 20 MYA, and modern Cebidae and Pitheciidae appeared ca. 16.9 and 15.6 MYA, respectively. The last common ancestor of living Atelidae is 12.4 million years old, making this clade the youngest New World primate family; at approximately the same time, modern Callitrichinae was evolving (11.8 MYA). The gap between the Platyrrhini/Catarrhini separation and the last common ancestor of living Platyrrhini may be as big as 20 million years. Paleontological and geoclimatological evidence corroborates that the sudden appearance of modern families may be a consequence of environmental changes during the Miocene.

Animal Migration↗
PubMed2004

Evolutionary relationships of major histocompatibility complex class I genes in simian primates.

New World monkeys (NWMs) occupy a critical phylogenetic position in elucidating the evolutionary process of major histocompatibility complex (MHC) class I genes in primates. From three subfamilies of Aotinae, Cebinae, and Atelinae, the 5'-flanking regions of 18 class I genes are obtained and phylogenetically examined in terms of Alu/LINE insertion elements as well as the nucleotide substitutions. Two pairs of genes from Aotinae and Atelinae are clearly orthologous to human leukocyte antigen (HLA) -E and -F genes. Of the remaining 14 genes, 8 belong to the distinct group B, together with HLA-B and -C, to the exclusion of all other HLA class I genes. These NWM genes are classified into four groups, designated as NWM-B1, -B2, -B3, and -B4. Of these, NWM-B2 is orthologous to HLA-B/C. Also, orthologous relationships of NWM-B1, -B2, and -B3 exist among different families of Cebidae and Atelidae, which is in sharp contrast to the genus-specific gene organization within the subfamily Callitrichinae. The other six genes belong to the distinct group G. However, a clade of these NWM genes is almost equally related to HLA-A, -J, -G, and -K, and there is no evidence for their orthologous relationships to HLA-G. It is argued that class I genes in simian primates duplicated extensively in their common ancestral lineage and that subsequent evolution in descendant species has been facilitated mainly by independent loss of genes.

5' Flanking Region↗
PubMed1989

Adenosine and its agonists cause retinal vasodilation and hemorrhages. Implications for ischemic retinopathies.

Animals were given a 0.1-mL intravitreous injection of various agents and followed up with frequent ophthalmoscopic examinations. Fundus photographs were performed before injection and at six and 24 hours after injection. Vascular caliber was assessed by a previously described technique of performing measurements on fundus photographs taken and projected in a standardized fashion. No significant vascular dilation was identified for vehicle alone, carbachol, histamine, isoproterenol hydrochloride, or bradykinin. Mild dilation within one hour, but not persisting for 24 hours, was noted for dibutyryl cyclic adenosine monophosphate. Prominent dilation within one hour, becoming maximal by five hours but not persisting for 24 hours, was noted for adenosine, dipyridamole, and sodium nitroprusside. The adenosine-induced vasodilation was effectively blocked by an adenosine receptor antagonist, BW-A1433U. N-ethylcarboxamidoadenosine (NECA), a nonspecific adenosine selective agonist, was a much more potent vasodilator than two relatively selective A1 adenosine agonists, N6-cyclopentyladenosine and N6-phenylisopropyladenosine, suggesting that A2 receptors are involved. The vascular dilation caused by adenosine, dipyridamole, and particularly NECA, but not nitroprusside or dibutyryl cyclic adenosine monophosphate, was accompanied by retinal hemorrhages, producing a picture reminiscent of some features of ischemic retinopathies. This study suggests that adenosine may be an important mediator of vasodilation, and therefore blood flow, in the retina.

Adenosine↗
PubMed1984

Epidemic non-A, non-B hepatitis in Nepal. Recovery of a possible etiologic agent and transmission studies in marmosets.

An epidemic of non-A, non-B hepatitis occurred in Kathmandu Valley, Nepal, during 1981-1982, with approximately 7.6% of households and 1.4% of individuals affected. Cases occurred preponderantly in the 15- to 34-year-old age group (70%), with most cases (75%) occurring in males. A high mortality rate (21%) occurred in pregnant women admitted to the hospital. No single water source was implicated, but epidemic peaks occurred during monsoon rains, and multiple opportunities for enteric transmission existed. One of eight patient stools examined by immune electron microscopy revealed aggregated, antibody-coated, 27-nm viruslike particles when convalescent serum samples were used as sources of antibody. Inoculation of two chimpanzees and four marmosets with a suspension of this stool resulted in elevated liver enzyme activity in three marmosets. Fecal excretion of 27-nm particles during the acute phase of disease (with temporally coincident antigen activity by radioimmunoassay) was observed in one marmoset, which also developed convalescent antibody against the particles in the original inoculum.

Adolescent↗
PubMed1997

Development of an enzyme-immunoassay (EIA) for the measurement of follicle-stimulating-hormone (FSH) in Callitrichid primates using a monoclonal antibody against the human-FSH-beta-subunit.

Despite the importance of Callitrichid primates in both biomedical and conservation research, practical and reliable immunoassays for the measurement of follicle-stimulating hormone (FSH) have not yet been described. A panel of monoclonal antibodies against specific peptide fragments within either the alpha or beta subunit of human FSH was evaluated for their ability to recognize FSH from Callitrichid and other New World primates. One of these, monoclonal antibody 46.3h6.b7 raised against human FSH, was selected due to its ability to recognize marmoset monkey FSH and its low crossreactivity with other gonadotrophins. The antibody formed the basis of an enzymeimmunoassay using a highly purified human urinary FSH (Metrodin, Serono) preparation coupled to biotin as label and unmodified as standard. After 24 h incubation, antibody bound label was visualized by addition of streptavidin-peroxidase followed by the appropriate substrate. Parallelism was obtained between the standard and dilutions of pituitary extracts, urine and plasma from the common marmoset (Callithrix jacchus) as well as from two tamarin species (Saguinus fuscicollis and S. oedipus) and one squirrel monkey (Saimiri sciureus). Profiles of plasma and urinary FSH during the follicular phase are shown for two individual marmosets. The ability to measure FSH in Callitrichidae provides new opportunities for studies of the reproductive biology of these New World primate species.

Animals↗
PubMed1997

Rate of metabolism in the smallest simian primate, the pygmy marmoset (Cebuella pygmaea).

Rate of metabolism was measured with six adult pygmy marmosets (Cebuella pygmaea) at regulated ambient temperatures ranging between 20 degrees C and 35 degrees C. A novel combined nest box and metabolic chamber was designed to allow nighttime measurements on immobile animals in their home cage without disturbance. The basal rate of metabolism (BMR) was 98 ml O2 h-1, representing 74% of the value expected from the equation of McNab [Quarterly Review of Biology 63:25-54, 1988] relative to body mass. The thermoneutral zone was approximately 27-34 degrees C. Below the lower critical temperature (27-28 degrees C), thermal conductance (12.9 ml O2 h-1 degree C-1) was close to the predicted value. Body temperature ranged between 34.9 degrees C and 35.5 degrees C at night. When two animals rested together overnight in the nest box, the lower critical temperature was slightly lowered, and individual energy expenditure at 20-21 degrees C was reduced by about 34%. The basal rate of metabolism of C. pygmaea is much lower than reported in an earlier study based on daytime measurements but agrees with values reported from a more recent study conducted at night with a classical metabolic chamber. In order to compare the BMR of C. pygmaea with that of other primates, 23 species were included in a comparative study taking into account both phylogeny and body mass (independent contrasts approach). The scaling exponent of BMR to body mass obtained was indistinguishable from that published for eutherian mammals in general. Cebuella and Callithrix exhibit the lowest basal rates known for simians. This trait may possibly be linked to the natural diet, which includes a large proportion of gums that are difficult to digest, but additional metabolic studies on primates are needed for further examination of its adaptive significance.

Animals↗
PubMed1997

Foraging ecology and use of space in wild golden lion tamarins (Leontopithecus rosalia).

In this paper we describe the use of space and feeding ecology of seven groups of golden lion tamarins observed for a total of 2,164 hr in Poço das Antas Reserve, Rio de Janeiro, Brazil. Relative to habitat availability in the home ranges of these groups, lion tamarins spent more time than expected in relatively undisturbed swamp forests and less time than expected in more degraded hillside and pasture habitats. Home range area was correlated with group biomass but not group size. Golden lion tamarins fed primarily on fruits and small animal prey, but relied heavily on floral nectar during seasonal periods of relatively low fruit availability. Compared to other New World monkeys, lion tamarins used larger home range areas and exhibited longer daily path lengths than would be predicted by group biomass alone. We suggest that this pattern of foraging and use of space may be explained by the relatively greater availability of cryptic prey and their microhabitats in forests that are flooded and/or have closed canopies than in forests that are in earlier stages of succession where prey may be more susceptible to desiccation during the dry season.

Animals↗
PubMed1997

Chromosomal similarities and differences between tamarins, Leontopithecus and Saguinus (Platyrrhini, Primates).

The karyotypes of two taxa of genus Leontopithecus (rosalia and chrysomelas) are studied. Their G-, C- and NOR-banding patterns are compared with those of representatives of the genus Saguinus to determine chromosomal similarities and differences between the two genera and thus contribute to explaining phylogenetic relations between the tamarins. Leontopithecus, like the Saguinus, presents 2n = 46, 14 autosomes plus the Y acrocentric and 30 autosomes plus the X biarmed. No chromosomal rearrangement distinguishes the karyotypes of the representatives of genus Leontopithecus or genus Saguinus. The two genera are distinguished from each other by a paracentric inversion and pericentric inversions on at least four pairs of acrocentric autosomes, displacing the NORs of the small short arms in Leontopithecus to the proximal region of the long arms in Saguinus or vice versa. The tamarins are also distinguished by the distribution of noncentromeric constitutive heterochromatin. The data obtained indicate that the two tamarin genera are closely related chromosomally, suggesting that they probably originated from the same ancestral branch.

Animals↗
PubMed1997

Ovarian function of pygmy marmoset daughters (Cebuella pygmaea) in intact and motherless families.

Reproductive inhibition of subordinate Callitrichid group members has been shown to vary with genus; whereas female Leontopithecus subordinates have normal ovarian cycles and occasionally breed within groups, subordinate Saguinus females almost never do so, with Callithrix species showing intermediate levels of reproductive inhibition. No information has been available on patterns of reproduction or inhibition in subordinate females in the genus Cebuella. We assessed fertility in Cebuella pygmaea daughters to allow comparison with the remaining Callitrichid genera. Specifically, the project had two goals: 1) to determine if there was evidence of reproductive inhibition of daughters living in family groups, and 2) to compare the ovarian function of daughters living in intact family groups with that of daughters residing in motherless families (i.e., without the breeding female). We collected daily urine samples for 6-8 weeks from eight pygmy marmoset daughters living in intact family groups or motherless families. Determination of ovulatory cycling or reproductive quiescence depended on the hormonal profiles generated from urinary luteinizing hormone and pregnanediol-3-glucuronide concentrations. All females in the motherless condition (aged 13-30 months) (n = 4) ovulated during the study. In contrast, only one of four daughters (aged 13-20 months) residing in intact families was found to be cycling. Data from motherless groups indicate ovarian cycling may begin between 15 and 17 months of age. Reproductive inhibition occurs in pygmy marmosets, although in a pattern more similar to Callithrix than to other Callitrichid genera.

Age Factors↗
PubMed1999

Proposed chromosomal phylogeny for the South American primates of the Callitrichidae family (Platyrrhini).

Cytogenetic and cytotaxonomic studies (G, C, sequential G/C, and NOR banding) were performed on 110 specimens representing the four genera of South American primates of the family Callitrichidae: Cebuella (C. pygmaea), Callithrix, groups argentata (C. argentata, C. emiliae, C. chrysoleuca, C. humeralifera, C. mauesi), and jacchus (C. aurita, C. geoffroyi, C. jacchus, C. kuhli, C. penicillata), Leontopithecus (L. chrysomelas, L. rosalia), and Saguinus (S. midas midas, S. m. niger). Mitotic chromosomes are characterized, and the rearrangements distinguishing the karyotypes of the taxa are inferred from arm homologies. The results were then converted into numerical data and submitted to cladistic analysis. The following conclusions were achieved: 1) Five karyotypic classes were observed, which correspond to the five taxa studied. Differences between them are as follows: a) Cebuella (2n = 44, 10 acrocentrics, A + 32 bi-armed autosomes, bi) and the argentata group (2n = 44, 10A + 32bi) are different from each other due to a reciprocal translocation; b) both can be distinguished from the jacchus group (2n = 46, 14A + 30bi) by a centric fusion/fission rearrangement and a paracentric inversion; c) Leontopithecus (2n = 46, 14A + 30bi) and Saguinus (2n = 46, 14A + 30bi) differ from the jacchus group by a reciprocal translocation and three paracentric inversions; and d) Saguinus is different from the others by one paracentric inversion and pericentric inversions in at least four pairs of acrocentric autosomes. 2) The cladistic analysis separates Cebus (used as an outgroup) from the Callitrichidae groups, which forms a clade. Among the Callitrichidae, marmosets (Cebuella and Callithrix) form a sub-clade, Cebuella and the argentata group being more closely related to each other than both are to the jacchus group. Tamarins (Leontopithecus and Saguinus) are also quite close, so that if one was not derived from the other, they with the marmosets share a common ancestor. Among the tamarins, Leontopithecus is karyotypically closest to the marmosets, specifically to the jacchus group. 3) Based on the chromosome information and considering the possible direction of the evolutionary changes (primitivity or phyletic dwarfism hypothesis, previously advanced by other authors), it was possible to propose the ancestral karyotypes and to develop two alternatives for the origin, differentiation and dispersion of the callitrichid. Both proposals are plausible, but when the geographical distribution is considered, the phyletic dwarfism hypothesis seems to be the most probable.

Animals↗
PubMed2000

Food sharing in black lion tamarins (Leontopithecus chrysopygus).

Food sharing behavior was investigated by studying 10 captive black lion tamarin (Leontopithecus chrysopygus) infants (six litters) between the ages of four and 26 weeks. The frequency of sharing by parents in response to infant begging increased steadily from the age of five to nine weeks, but then declined gradually, although infants were still receiving food even at 26 weeks. Until the age of 15 weeks, infants received more food items by transfer from other group members than they did from self-feeding. Thereafter, self-feeding predominated. Offering of food by adults without prior infant begging occurred at low frequencies (5.3% of items transferred) and ceased at 20 weeks of age. Begging success (the proportion of infant begs which resulted in food sharing) remained relatively constant, averaging 65%. In common with other lion tamarins, black lion tamarins appear to continue to share food with infants well after weaning, and until at least six months of age.

Aging↗
PubMed1983

Transplacental and direct exposure of mouse and marmoset to ethylnitrosourea: analysis of chromosome aberrations.

The effect of ethylnitrosourea (ENU) on chromosomes of mouse bone marrow cells and transplacentally exposed embryonic liver cells was investigated. Chromosome aberrations were found to be dose- and time-dependent. The maximum damage was seen 6 h after the exposure. Chromosome aberrations were also induced in bone marrow cells and lymphocytes of marmosets (Callithrix jacchus) directly exposed to ENU. Aberrations did not, however, occur in offspring whose mothers were treated with ENU before conception. Furthermore, chronic transplacentally exposed offspring have been analyzed. The frequency of chromosome aberrations was not increased in their lymphocytes and fibroblasts. The elimination of chromosome aberrations during embryogenesis is discussed.

Animals↗
PubMedDate not supplied

The effects of neonatal exposure to testosterone on the development of behaviour in female marmoset monkeys.

Experimental investigations of sexual differentiation in primates have been mainly confined to the rhesus monkey, a highly polygamous species with marked anatomical and behavioural sexual dimorphism. The marmoset is a monogamous monkey which shows little anatomical or behavioural sexual dimorphism, and both sexes exhibit positive feedback in response to the administration of oestradiol. This monkey has a relatively short gestation period of 144 days and usually gives birth to dizygotic twins. These share a common placental circulation and hence develop as haematopoietic chimaeras. However, a female with a male co-twin is not adversely affected as a result of this and the freemartin condition does not occur. Since the newborn male experiences raised testosterone levels soon after birth it is possible that the 'critical period' for sexual marmosets were implanted with 25 mg of testosterone for 50 days after birth. After removal of the implants their genitalia remained partly masculinized and they initiated more masculine rough-and-tumble play than their controls. After puberty they exhibited a mixture of male and female sexual behaviour when presented with unfamiliar normal males and females during 15-minute behavioural trials. Four of the implanted females have also ovulated. Neonatal administration of testosterone therefore has had an organizing effect on female behaviour. Whether the marmoset is exceptional in this respect, or whether other primates which exhibit a male neonatal testosterone surge, such as man and the rhesus monkey, also undergo some postnatal behavioural differentation, remains to be seen.

Animals↗
PubMed1978

Immunological interference with the maternal recognition of pregnancy in primates.

If chorionic gonadotropin is involved, as part of the luteotrophic stimulus, in the maternal recognition of pregnancy in primates, then immunization against the beta subunit of hCG should prevent a conception going beyond the length of the normal cycle. Immunization against hCG-beta suppresses fertility in marmoset monkeys, baboons and rhesus monkeys, as long as the antibody titres remained high. As titres decline, however, female marmosets experience recurrent abortions interspersed with occasional live births. Young marmosets born to mothers with low circulating levels of antibody reach apparently normal sexual maturity. Immunization against hCG-beta subunit may have potential as a possible long-term method of fertility control in humans, but its reversibility needs further study. There is still a lack of basic knowledge of the functions of chorionic gonadotropin, especially now that its restriction to pregnancy seems improbable. Immunization against hCG may be valuable as a research tool with which to study the immunological relationships between mother and fetus during early pregnancy.

Animals↗
PubMed1975

Fine structural observations on hemopoiesis in the chorioallantoic placenta of the marmoset.

Hemopoietic sinuses in the chorionic trabeculae of marmoset placenta were examined electron microscopically at several stages of pregnancy. Tissues were prepared both by standard technique and following injection of exogenous peroxidase into the maternal circulation prior to autopsy, and subsequent cytochemical localization of its reaction product in the fetal placenta. Aside from their dilated size and cellular content, the sinuses resembled the allantoic capillaries of the peripheral umbilical circulation in this species; and in early and midgestational placentas, sinusal lumina, differentiating elements in the erythroid line were present in placentas at all stages. Such cells appeared to arise both by a process of proliferation of undifferentiated progenitors from the sinusal lining and by mitosis of pre-existing erythroid cells. Only the latter process was observed in the mature placenta near term. Granulopoiesis was not observed at any stage; on the other hand, cells in the thromboid line were identified in placentas believed to be near midgestation; and large intrasinusal phagocytes were present in both midgestational and late placentas. In the latter, they were seen to have endocytosed peroxidase, and, by tenuous, dendriform processes, to be related anatomically to large numbers of erythroid cells. Early in gestation, the developing erythroid elements were closely related by areas of contact, both to each other and to the delimiting endothelium of the sinuses.

Allantois↗
PubMed1985

Early implantation stages in the marmoset monkey (Callithrix jacchus).

The morphology of the initial stages of implantation in the marmoset monkey (Callithrix jacchus) was studied by obtaining embryos and associated endometrium at timed intervals after ovulation. Estrus cycles were detected by measuring daily levels of plasma progesterone. Following a short follicular phase, circulating levels of progesterone above 20 ng/ml were taken as representing day 1 after ovulation. On this basis, single, twin, and triplet embryos were recovered from six perfused-fixed females on days 13, 16, 19, 23, and 29 after ovulation and prepared in resin for light microscopy. Early implantation stages, 13 and 16 days after ovulation, were characterized by the intrusion of syncytial trophoblast between epithelial cells of the endometrium with minimal cellular damage. Some hyperplasia of epithelium at the margin of the implantation site was evident. The consolidation of the initial attachment was achieved by an increase in syncytial trophoblast underlying the inner cell mass of the embryo which rapidly surrounded and breached maternal capillaries. Although initially separate, the chorions of twin or triplet embryos started to fuse by day 19 after ovulation. This process was complete by day 29 such that embryos shared a common uterine exocoelom surrounded by continuous trophoblast. It was concluded that implantation in the marmoset monkey commenced on days 11-12.5 after ovulation and involved an intrusive mechanism. Although trophoblast penetration of endometrium was superficial, maternal capillaries were tapped at an early stage of implantation. The fusion of chorions of twins and triplets first occurred around day 19 after ovulation.

Animals↗
PubMed1980

Studies of marmoset megakaryocytopoiesis in vitro.

Liquid culture of the mononuclear fraction of the blood of marmosets without any added stimulator resulted in the appearance of megakaryocytes. These cells could not be identified by light microscopy or by indirect immunofluorescence using antiplatelet antiserum. Ultrastructural identification was made using platelet peroxidase. Some megakaryocytes demonstrated sparse but detectable demarcation membranes, early granule formation, and platelet formation. The results indicate that marmoset megakaryocytic progenitor cells circulate and can begin to differentiate in vitro, although unstimulated liquid culture conditions do not promote the development of the usual light-microscopic features of differentiation.

Animals↗