Search

Chronic emesis (CE) is a poorly understood condition in human and nonhuman primates that negatively impacts the quality of life. Early identification of risk factors for the development of CE is likely to improve the ability to manage CE cases successfully and is, therefore, desirable. Using a case-control study, we reviewed the necropsy records of the California National Primate Research Center and identified 24 animals with recorded CE, defined as five or more incidents of emesis in 1 month. A group of 89 healthy rhesus macaques (Macaca mulatta), comparable in age and percent time housed indoors, was similarly identified. Next, we investigated the association between the occurrence of CE during later stages of life after infancy and the behavioral temperament scores attained in infancy, age, sex, birth location, rearing condition, history of self-injurious behavior (SIB), and the number of lifetime sedation events. Our analysis revealed that CE was associated with degrees of temperament constructs obtained in infancy (data was available for n = 113), such as Confidence (odds ratio (OR) = 0.45, 95% CI: 0.18, 1.08, p = 0.07), Gentleness (OR = 0.47, 95% CI: 0.23, 0.96, p = 0.03), Nervousness (OR = 2.04, 95% CI: 0.98, 4.23, p = 0.05), and Vigilance (OR = 0.36, 95% CI: 015, 0.87, p = 0.02), suggesting that CE is linked to behavioral phenomenon measured in early life, long before it becomes a medical concern. Our data suggest that CE was positively correlated with a history of SIB (OR 4.26, 95% CI: 0.98, 18.47, p = 0.04). Accurate prediction of CE can then assist behavioral and colony management professionals in making informed decisions regarding the care of animals at risk of developing CE. Moreover, the novel information we reported here could have valuable implications in human medicine, where gastrointestinal distress is a common complaint affecting a person's quality of life.

Rhesus monkeys and humans are highly social primates, yet both species exhibit pronounced variation in social functioning, spanning a spectrum of sociality. Naturally occurring low sociality in rhesus monkeys may be a promising construct by which to model social impairments relevant to human autism spectrum disorder (ASD), particularly if low sociality is found to be stable across time and associated with diminished social motivation. Thus, to better characterize variation in sociality and social communication profiles, we performed quantitative social behavior assessments on N = 95 male rhesus macaques (Macaca mulatta) housed in large, outdoor groups. In Study 1, we determined the social classification of our subjects by rank-ordering their total frequency of nonsocial behavior. Monkeys with the greatest frequency of nonsocial behavior were classified as low-social (n = 20) and monkeys with the lowest frequency of nonsocial behavior were classified as high-social (n = 21). To assess group differences in social communication profiles, in Study 2, we quantified the rates of transient social communication signals, and whether these social signals were initiated by or directed towards the focal subject. Finally, in Study 3, we assessed the within-individual stability of sociality in a subset of monkeys (n = 11 low-social, n = 11 high-social) two years following our initial observations. Nonsocial behavior frequency significantly correlated across the two timepoints (Studies 1 and 3). Likewise, low-social versus high-social classification accurately predicted classification two years later. Low-social monkeys initiated less prosocial behavior than high-social monkeys, but groups did not differ in receipt of prosocial behavior, nor did they differ in threat behavior. These findings indicate that sociality is a stable, trait-like characteristic and that low sociality is linked to diminished initiation of prosocial behavior in rhesus macaques. This evidence also suggests that low sociality may be a useful construct for gaining mechanistic insight into the social motivational deficits often observed in people with ASD.

Rhesus macaques (Macaca mulatta) are amongst the most common nonhuman primate species used in biomedical research. These animals provide a precious resource for translational studies and opportunities to maximize rhesus data use are encouraged. Here we compile data produced from 10 years of investigator‐driven pregnancy studies conducted at the Oregon National Primate Research Center (ONPRC). All pregnancies were generated within the consistent and reproducible protocols of the ONPRC time‐mated breeding program. The data included are from control animals who did not experience in utero perturbations or experimental manipulations. A total of 86 pregnant rhesus macaques were delivered by cesarean section over a range of gestational days (G) 50 to G159 (where term is G165 ± 10 days in the rhesus macaque), with subsequent immediate tissue harvesting following standardized protocols. Fetal and placental growth measures, and all major organ weights are reported. All data are presented relative to gestational age for the entire cohort and in addition, data are stratified by fetal sex. The outcome is a large reference resource for use by laboratory animal researchers in future comparative fetal development studies. Research Highlights: Generation of a rhesus macaque reference data set for placental and fetal growth measurements as a resource for laboratory animal researchers.Developmental biometric measurements from pregnancies generated as part of the time‐mated breeding program at the Oregon National Primate Research Center.Stratification of cross‐sectional first, second, and third trimester growth data by fetal sex. [ABSTRACT FROM AUTHOR]

Nonhuman primates are important preclinical models for translational, reproductive, and developmental science. Clinical evaluation of human fetal development is performed using standard sonographic‐derived fetal biometry, assessments of amniotic fluid, and uteroplacental hemodynamics. These noninvasive in utero measurements provide important information regarding fetal growth and pregnancy well‐being. Abnormalities in fetal growth, amniotic fluid volume, or placental vascular function are associated with placental insufficiency and adverse perinatal outcomes including stillbirth. The fetal biometric parameters most commonly assessed are biparietal diameter, head circumference, abdominal circumference, and femur diaphysis length. Evaluation of amniotic fluid volume includes measuring the fluid in four quadrants of the uterus to generate an Amniotic Fluid Index. Measures of uteroplacental hemodynamics typically include doppler assessment of the umbilical artery and ductus venosus, but can also include interrogation of the uterine artery and umbilical vein. In this study, we compile prenatal ultrasound data of fetal biometry, amniotic fluid measurements, and uteroplacental hemodynamics obtained from pregnancy studies conducted at the Oregon National Primate Research Center. The data included are from control unperturbed pregnant animals who have not undergone in utero experimental manipulations. This is the first report of comprehensive sonographic measurements following standardized clinical obstetric protocols utilized in rhesus macaques. The outcome is a large, prenatal ultrasound resource to be used by laboratory animal researchers in future nonhuman primate pregnancy studies for antenatal assessment. Research highlights: Nonhuman primates are important preclinical models for translational, reproductive, and developmental science.Clinical evaluation of human fetal development is performed using standard sonographic‐derived fetal biometry, assessments of amniotic fluid, and uteroplacental hemodynamics.Nomograms generated by this study can be used in nonhuman primate pregnancies to determine if there is concern for fetal growth restriction or placental insufficiency.This is the first report of comprehensive sonographic measurements following standardized clinical obstetric protocols utilized in rhesus macaques. [ABSTRACT FROM AUTHOR]

Most primate species are highly social. Yet, within species, pronounced individual differences in social functioning are evident. In humans, the Social Responsiveness Scale (SRS) measures variation in social functioning. The SRS provides a quantitative measure of social functioning in natural social settings and can be used as a screening tool for autistic traits. The SRS was previously adapted for use in chimpanzees and recently refined for rhesus macaques, resulting in the macaque Social Responsiveness Scale-Revised (mSRS-R). Here, we performed an exploratory factor analysis on the mSRS-R in a large sample of male rhesus macaques (N = 233). We investigated the relationships of the resulting mSRS-R factors to quantitative social behavior (alone, proximity, contact, groom, and play) and to previously-established personality dimensions (Sociability, Confidence, Irritability, and Equability). Factor analysis yielded three mSRS-R factors: Poor Social Motivation, Poor Social Attractiveness, and Inappropriate Behavior. mSRS-R factors mapped closely to social behavior and personality dimensions in rhesus macaques, providing support for this instrument's convergent and discriminant validity. Animals with higher Poor Social Motivation were more likely to be observed alone and less likely to be observed in contact and grooming with conspecifics. Animals with higher Poor Social Attractiveness were less likely to be observed playing but more likely to be observed grooming with conspecifics. Inappropriate Behavior did not predict any behavioral measure. Finally, animals with higher Poor Social Motivation and higher Poor Social Attractiveness had less sociable personalities, whereas animals with more Inappropriate Behavior were more confident and more irritable. These findings suggest that the mSRS-R is a promising, psychometrically robust tool that can be deployed to better understand the psychological factors contributing to individual differences in macaque social functioning and, with relevant species-specific modification, the SRS may hold promise for investigating variation in social functioning across diverse primate taxa.

Understanding the behavior of primates is important for primatology, for psychology, and for biology more broadly. It is also important for biomedicine, where primates are an important model organism, and whose behavior is often an important variable of interest. Our ability to rigorously quantify behavior has, however, long been limited. On one hand, we can rigorously quantify low‐information measures like preference, looking time, and reaction time; on the other, we can use more gestalt measures like behavioral categories tracked via ethogram, but at high cost and with high variability. Recent technological advances have led to a major revolution in behavioral measurement that offers affordable and scalable rigor. Specifically, digital video cameras and automated pose tracking software can provide measures of full‐body position (i.e., pose) of primates over time (i.e., behavior) with high spatial and temporal resolution. Pose‐tracking technology in turn can be used to infer behavioral states, such as eating, sleeping, and mating. We call this technological approach behavioral imaging. In this review, we situate the behavioral imaging revolution in the history of the study of behavior, argue for investment in and development of analytical and research techniques that can profit from the advent of the era of big behavior, and propose that primate centers and zoos will take on a more central role in relevant fields of research than they have in the past. Research highlights: Recent advances in technology permit the automated tracking of primates.Automated tracking promises several benefits to biology and biomedicine.Zoos and primate centers are likely to be more important in the era of behavioral tracking. [ABSTRACT FROM AUTHOR]

Living near primate species has positive and negative outcomes for human communities. While most studies focus on understanding people's perceptions regarding the adverse consequences of interacting with primates, less is known about people's willingness to coexist with primates or reasons that may promote human–primate coexistence. We surveyed 794 people co‐living with four different primate species—rhesus macaque Macaca mulatta, bonnet macaque Macaca radiata, lion‐tailed macaque Macaca silenus, and Hanuman langur Semnopithecus dussumieri—in southern and western India to understand how people perceived the costs and benefits of coexistence. The results of our semi‐structured interview study revealed that although tangible costs (i.e., financial losses from primate depredation) primarily drive people's stated tolerance for primate presence, intangible benefits from primates (i.e., their ecological, existence, sentience, and religious values) also critically affect attitudes towards coexistence. Amongst the four species, people associated rhesus macaques with the greatest costs and fewest benefits, lion‐tailed macaques with the lowest costs, and bonnet macaques with the highest benefits. People preferred lion‐tailed macaques and Hanuman langurs more than bonnet and rhesus macaques, and affection for a species shaped how people viewed costs accruing from the species. People's preferences for species were influenced by their existence, ecological, and sentience values more than their religious value. We suggest that intangible benefits influence people's fondness for a primate species and this, in turn, shapes how people perceive costs resulting from the species. Hence strengthening people's perceptions of the intangible benefits they receive from primate species will improve human tolerance for living near primates. We argue that there is a need to understand the context of human–primate conflicts beyond the cost aspects and focus on the benefits to improve human–primate coexistence. Research Highlights: In a study of how humans perceive four Indian nonhuman primates, we found that: Tangible costs and intangible benefits affected people's tolerance for co‐living with nonhuman primates.Financial costs from primate crop damage were the biggest barrier for coexistence.Species' existence, ecological, and sentience values shaped affection for the species, and this influenced perception of species' costs. [ABSTRACT FROM AUTHOR]

There are some predictable patterns of trauma in captive rhesus macaque (Macaca mulatta) social groups. Several factors have been documented to contribute to these patterns, including group formation of unrelated animals, and the establishment of dominance ranks. Here, we report on how socially induced trauma in groups of rhesus monkeys is influenced by the breeding season, numbers of matrilines per group and matriline size. We analyzed 3 years of data collected from veterinary admittance logs for four groups in our specific pathogen free (SPF) breeding colony. Since the groups differed in time from formation, both the numbers of matrilines and the composition of those matrilines were different. Across the four groups, trauma rates were significantly higher during the fall breeding season than the spring and summer months when births occur. The group that was formed most recently, comprised of the greatest number of matrilines but fewest related animals, showed significantly higher rates of trauma than the older social groups. Further, the middle and lowest ranking families received signifincantly higher rates of trauma than the highest ranking families, suggesting a rank–related phenomenon. Additionally, there was a significant negative correlation between numbers of adult females in a matriline and rates of trauma observed in each matriline, but the numbers of adult females are significantly higher in the top ranked families compared to all of the other matrilines. These findings suggest that trauma rates increase during the breeding season and may be exacerbated in recently formed breeding groups that have smaller matrilines and reduced opportunities for social support to mitigate rank‐related aggression. Management practices should be devised to ensure adequate matrilineal size to decrease rates of trauma in captive rhesus macaque groups. [ABSTRACT FROM AUTHOR]

The social relationships that individuals experience at different life stages have a non‐negligible influence on their lives, and this is particularly true for group living animals. The long lifespan of many primates makes it likely that these animals have various tactics of social interaction to adapt to complex changes in environmental or physical conditions. The different strategies used in social interaction by individuals at different life stages, and whether the position (central or peripheral) or role (initiator or recipient) of an individual in the group social network changes with age, are intriguing questions that remain to be investigated. We used social network analysis to examine age‐related differences in social interaction patterns, social roles, and social positions in three affiliative social networks (approach, allogrooming, and social play) in a group of wild rhesus macaques (Macaca mulatta). Our results showed that social interaction patterns of rhesus macaques differ between age classes in the following ways: i) young individuals tend to allocate social time to a high number of groupmates, older individuals prefer to focus on fewer, specific partners; ii) as they grow older, individuals tend to be recipients in approach interactions and initiators in grooming interactions; and iii) regardless of the different social interaction strategies, individuals of all ages occupy a central position in the group. These results reveal a possible key role played by immature individuals in group social communication, a little‐explored issue which deserves closer investigation in future research. [ABSTRACT FROM AUTHOR]

In the past decade, many researchers have published papers about hybridization between long-tailed and rhesus macaques. These previous works have proposed unidirectional gene flow with the Isthmus of Kra as the zoogeographical barrier of hybridization. However, these reports analyzed specimens of unknown origin and/or did not include specimens from Thailand, the center of the proposed area of hybridization. Collected specimens of long-tailed and rhesus macaques representing all suspected hybridization areas were examined. Blood samples from four populations each of long-tailed and rhesus macaques inhabiting Thailand, Myanmar, and Laos were collected and analyzed with conspecific references from China (for rhesus macaques) and multiple countries from Sundaic regions (for long-tailed macaques). Ninety-six single nucleotide polymorphism (SNP) markers specifically designed to interrogate admixture and ancestry were used in genotyping. We found genetic admixture maximized at the hybrid zone (15-20°N), as well as admixture signals of varying strength in both directions outside of the hybrid zone. These findings show that the Isthmus of Kra is not a barrier to gene flow from rhesus to long-tailed populations. However, to precisely identify a southernmost barrier, if in fact a boundary rather than simple isolation by distance exists, the samples from peninsular Malaysia must be included in the analysis. Additionally, a long-tailed to rhesus gene flow boundary was found between northern Thailand and Myanmar. Our results suggest that selection of long-tailed and rhesus macaques, the two most commonly used non-human primates for biomedical research, should take into account not only the species identification but also the origin of and genetic admixture within and between the species. [ABSTRACT FROM AUTHOR]

The lower reproductive tract of nonhuman primates is colonized with a diverse microbiota, resembling bacterial vaginosis (BV), a gynecological condition associated with negative reproductive outcomes in women. Our 4 aims were to: (i) assess the prevalence of low Lactobacilli and a BV-like profile in female rhesus monkeys; (ii) quantify cytokines in their cervicovaginal fluid (CVF); (iii) examine the composition and structure of their mucosal microbiota with culture-independent sequencing methods; and (iv) evaluate the potential influence on reproductive success. CVF specimens were obtained from 27 female rhesus monkeys for Gram's staining, and to determine acidity (pH), and quantify proinflammatory cytokines. Based on Nugent's classification, 40% had a score of 7 or higher, which would be indicative of BV in women. Nugent scores were significantly correlated with the pH of the CVF. Interleukin-1ß was present at high concentrations, but not further elevated by high Nugent scores. Vaginal swabs were obtained from eight additional females to determine microbial diversity by rRNA gene amplicon sequencing. At the phylum level, the Firmicutes/Bacteroidetes ratio was low. The relative abundance of Lactobacilli was also low (between 3% and 17%), and 11 other genera were present at >1%. However, neither the microbial diversity in the community structure, nor high Nugent scores, was associated with reduced fecundity. Female monkeys provide an opportunity to understand how reproductive success can be sustained in the presence of a diverse polymicrobial community in the reproductive tract. [ABSTRACT FROM AUTHOR]

The rhesus macaque ( Macaca mulatta) is the most widely distributed nonhuman primate species in the world, with six subspecies distributed through China. From 2012 to 2014, we conducted studies on the body mass and morphological variation of the southernmost subspecies M. m. brevicaudus in Nanwan Nature Reserve for Rhesus Macaque, Hainan, China. We compared measurements with other populations of this species. We also investigated the inter-group body mass variation from seven provisioned free-ranging groups in our study site. Our results show that M. m. brevicaudus has the smallest body size, the smallest body mass, and the shortest tail among rhesus macaque subspecies. Its sexual dimorphism score is also among the lowest, which is similar to other southern distributed subspecies in China, but smaller than northern distributed subspecies. We found that the average body mass of female macaques is not correlated with their dominance ranks. There are significant differences in body mass among the seven adjacent study groups at the same site, suggesting the existence of inter-group competition. Average body mass of a group is better described by a quadratic function of group size than a linear one as predicted by the socio-ecological model. Am. J. Primatol. 78:679-698, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Frugivorous primates are important seed dispersers and their absence from forest patches is predicted to be detrimental to tropical forest regeneration and recruitment. With the reduction of primate populations globally, ecologically resilient primate species, characterized by dietary flexibility and the ability to thrive in a variety of habitats, assume new importance as seed dispersers. The most widely distributed non-human primate, the rhesus macaque Macaca mulatta has been intensively studied but little is known about its role in maintaining ecosystem structure and functions. Due to their frugivorous diet, large group sizes, large home ranges and tolerance to disturbance, rhesus macaques may be effective seed dispersers. We studied seed dispersal by rhesus macaques at the Buxa Tiger Reserve, India, through a combination of behavioural observations and germination experiments. Rhesus macaques dispersed 84% of the 49 species they fed on either through spitting or defecation. Nearly 96% of the handled seeds were undamaged and 61% of the species for which germination tests were performed had enhanced germination. Almost 50% of the monitored seeds among those deposited in situ germinated and 22% established seedlings, suggesting that rhesus macaques are important seed dispersers in tropical forests. Due to their widespread distribution and large populations, rhesus macaques are perceived as common and are categorized as Least Concern on the IUCN Red List, effectively excluding them from any conservation plans. Based on the results of our study, we argue that rhesus macaques fulfill critical ecological functions in their habitat and that this parameter must be taken into consideration when they are reviewed for conservation priorities. Am. J. Primatol. 76:1175-1184, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

While studies of rhesus macaques ( Macaca mulatta) in the eastern (e.g., China) and western (e.g., India) parts of their geographic range have revealed major genetic differences that warrant the recognition of two different subspecies, little is known about genetic characteristics of rhesus macaques in the transitional zone extending from eastern India and Bangladesh through the northern part of Indo-China, the probable original homeland of the species. We analyzed genetic variation of 762 base pairs of mitochondrial DNA from 86 fecal swab samples and 19 blood samples from 25 local populations of rhesus macaque in Bangladesh collected from January 2010 to August 2012. These sequences were compared with those of rhesus macaques from India, China, and Myanmar. Forty-six haplotypes defined by 200 (26%) polymorphic nucleotide sites were detected. Estimates of gene diversity, expected heterozygosity, and nucleotide diversity for the total population were 0.9599 ± 0.0097, 0.0193 ± 0.0582, and 0.0196 ± 0.0098, respectively. A mismatch distribution of paired nucleotide differences yielded a statistically significantly negative value of Tajima's D, reflecting a population that rapidly expanded after the terminal Pleistocene. Most haplotypes throughout regions of Bangladesh, including an isolated region in the southwestern area (Sundarbans), clustered with haplotypes assigned to the minor haplogroup Ind-2 from India reflecting an east to west dispersal of rhesus macaques to India. Haplotypes from the southeast region of Bangladesh formed a cluster with those from Myanmar, and represent the oldest rhesus macaque haplotypes of Bangladesh. These results are consistent with the hypothesis that rhesus macaques first entered Bangladesh from the southeast, probably from Indo-China, then dispersed westward throughout eastern and central India. Am. J. Primatol. 76:1094-1104, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Resistin protein is thought to link insulin resistance in murine models of obesity and type-2 diabetes, but the role of resistin in human studies of inflammatory metabolic disorders have generated conflicting data. Here, we describe the structure of the resistin gene using adipose tissue from non-human primates (NHPs), which have been used extensively to model a host of human diseases. Full-length cDNA from rhesus macaque resistin obtained by rapid amplification of cDNA ends (RACE) is comprised of 526 nucleotides covering an open-reading frame (ORF) that encodes a 108-amino-acid protein that is 92% homologous with the human counterpart but only 60% homologous with the murine counterpart. Using a modified polymerase chain reaction technique, we identified single nucleotide polymorphisms and a 78-bp deletion within resistin cDNA of nine rhesus macaques. Comparisons of the full-length cDNA sequence and an amplified 569-bp genomic DNA sequence revealed an error in published predictions arising from genomic studies about the gene's exon 3 region. Our data show, for the first time, the full-length macaque resistin cDNA sequence (GenBank: JF740676.1). These findings will illuminate future studies into the role of resistin in NHP models of inflammatory metabolic diseases. Am. J. Primatol. 76:65-71, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Studies on early development have demonstrated the profound effects of early social experience on the behavioral development and physiology of young rhesus macaques. Given these relationships, we hypothesized that rhesus macaques exposed to different nursery-rearing conditions may develop unique biobehavioral profiles. If this is true, the assessment of temperament may allow us to pinpoint successful rearing environments, thus improving the overall health of nonhuman primates that are raised in captive environments. We conducted biobehavioral assessments in order to examine differences in the development of infants raised under four different peer-rearing conditions (continuous pairing (CP), intermittent pairing, CP with partner rotation, and intermittent rotational pairing) and compared these animals with data from a mother-reared control group. Overall, continuous rotationally paired animals were most similar to mother-reared controls on most behavioral and temperament measures, suggesting that more socially complex rearing environments (greater number of social partners) favor a more active behavioral style. Cortisol profiles of mother-reared controls were similar to both CP groups, and these three groups had higher cortisol concentrations than the intermittent rotational-pairing group. In addition, intermittently paired infants displayed a significantly higher frequency of self-stroke behavior during a human intruder challenge, an abnormal behavior also known as floating limb which has been shown to be a precursor of self-biting. Overall, the data are consistent with the idea that social complexity in the nursery, as operationalized in our continuous rotational pairing, leads to a biobehavioral profile that is most similar to that of infants raised by their mothers in large, socially complex, cages. Am. J. Primatol. 73:692-701, 2011. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

John Bowlby defined offspring-parent attachment as a relationship in which an infant or child uses one or a few preferred adults as a secure base from which to explore and as a haven of safety. He defined attachment security in terms of confidence in the adult's availability and responsiveness and the smooth organization of exploration and proximity seeking. Developmental psychologists have found this perspective productive in both observational and laboratory research. At the same time, they emphasize that such a construct cannot be operationalized in terms of one or a few behaviors. Instead, naturalistic observations of human infant attachment typically employ the Q-sort method to develop the Attachment q-set (AQS), 90 behaviorally descriptive items sorted in terms of how characteristic each item is of the infant's typical behavior. Meta-analyses of research using the AQS attest to its reliability and validity. This article reports an adaptation of the AQS to the task of assessing infant attachment security in nonhuman primates and illustrates its use. The availability of comparable measures of attachment security will contribute to an expanded understanding of patterns of attachment behavior in nonhuman primate societies and will facilitate interaction between comparative and developmental psychologists. Am. J. Primatol. 73:109-118, 2011. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Records from a colony of captive Indian rhesus macaques (Macaca mulatta) were used to estimate heritability for a number of reproductive traits. Records were based on a total of 7,816 births by 1,901 females from 1979 to 2007. Heritability was estimated with a linear animal model using a multiple trait derivative free REML set of programs. Because no male parents were identified, the numerator relationship matrix contained female kinships established over six generations. Reproductive traits included female age at the birth of the first, second and last infant, age at death, inter-birth intervals, number of infants born per female and infant survival. Heritability for each trait was estimated as the ratio of the additive genetic variance to phenotypic variance adjusted for significant fixed effects. Estimates of heritability for early reproduction ranged from 0.000±0.072 for birth interval after the first reproduction to 0.171±0.062 for age of female at the first infant. Higher estimates of heritability were found for female longevity [0.325±0.143] and for productivity of deceased females born before 1991 [0.221±0.138]. Heritability for infant survival ranged from 0.061±0.018 for survival from 30 days to 1 year to 0.290±0.050 for survival from birth to 30 days when adjusted to an underlying normal distribution. Eight of the 13 estimates of heritability for reproductive traits in this study were different from zero [P<0.05]. Generally, heritability estimates reported in this study for reproductive traits of captive rhesus macaque females are similar to those reported in the literature for free-ranging rhesus macaque females and for similar reproductive traits of other species. These estimates of heritability for reproductive traits appear to be among the first for a relatively large colony of captive rhesus macaque females. Am. J. Primatol. 72:811–819, 2010. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Positive reinforcement training (PRT) efficiency was examined as a function of training frequency in 33 pair- or triple-housed female rhesus macaques. The animals were trained three times a week, once a day or twice a day, using PRT and a clicker as a secondary reinforcer. All animals were trained on 30 sessions, with an average of 5 min per training session per animal. The behaviors, trained in succession, were Targeting (reliably touching and following a Target); Collaborating (dominant animals allowing subordinates to train while stationing); Box-training (accepting being enclosed in a small compartment while responding to Target training) and initial Injection training. Fulfilled criteria for Targeting were obtained in 32/33 animals in a median of nine training sessions. Collaboration was obtained in 27/33 animals in a median of 15 training sessions. However, only four animals completed Box-training during the 30 training sessions and started Injection training. When comparing training success in terms of number of training sessions, training twice a day was less efficient than the other two treatments. In terms of daily progress, our results suggest that from a management perspective, daily training is more conducive to quick training success than thrice weekly training. In addition, in this study no further advantages could be gained from training twice a day. Am. J. Primatol. 71:373–379, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Operant conditioning using positive reinforcement techniques has been used extensively in the management of nonhuman primates in both zoological and laboratory settings. This research project was intended to test the usefulness of counter-conditioning techniques in reducing the fear-responses of singly housed male rhesus macaques living in the laboratory environment. A total of 18 male rhesus macaques (Macaca mulatta) were selected for this project and randomly assigned to one of three groups: a desensitization training group, a husbandry training group, or a control group. Behavioral data were collected before and after a 6 weeks training and/or habituation period during which the first two groups received a total of 125 min of positive reinforcement training (and also were assumed to undergo habituation to the environment) and the control group experienced only simple habituation to the environment. Based on a Wilcoxon Matched-Pairs Sign Test, we found that a significant proportion of animals exposed to desensitization training showed a reduction in the rate at which they engaged in cringing toward humans (exact significance=0.016, one-tailed, N–ties=6), cringing in general (exact significance=0.016, one-tailed, N–ties=6), and in stress-related behaviors (exact significance=0.016, one-tailed, N–ties=6). This was not the case for animals exposed to basic husbandry training or animals in the control group. A significant proportion of desensitization-exposed animals also showed a reduction in the duration of time spent cringing toward humans (exact significance=0.016, one-tailed, N–ties=6), but not in cringing behaviors in general or in stress-related behaviors. There were not a significant proportion of animals in either the husbandry training group or the control group that showed a decrease in duration of these behaviors. Results of this study could enhance both laboratory animal welfare and laboratory animal research, and could be a first step in developing techniques for reducing fearful behavior in rhesus monkeys in the laboratory environment. Am. J. Primatol. 71:30–39, 2009. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

This study was designed to assess the effects of various cryopreservation protocols on the postthaw survival of rhesus macaque sperm. Multiple ejaculates of five mature males were collected and frozen by each of four different methods. Cryopreservation significantly reduced motility in all samples, regardless of the method, and the response of different ejaculates of the same male to each method proved to be consistent. The freezing method was a significant factor in determining the immediate postthaw motility, although this effect disappeared after 4 hr. Moreover, there was a significant interaction between individual males and freezing method suggesting that developing a single freezing protocol that is universally suitable may be difficult. Am. J. Primatol. 70:1093–1096, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Ketamine hydrochloride is frequently administered to non-human primates as a means of chemical restraint. This procedure can be a frequent source of stress to monkeys at research facilities, impacting animal health, well-being and research quality. This study was designed to measure ketamine's effect on daily food intake, a parameter that reflects and influences animal well-being and directly impacts research studies. On five occasions, baseline daily food intake was compared to daily food intake occurring 24, 48, 72, 96, and 120 h after an intramuscular injection of 10 mg/kg ketamine in male African green monkeys (AGMs) (Cercopithecus aethiops) and male and female rhesus macaques (Macaca mulatta). AGMs and female rhesus macaques had significantly reduced daily food intake during the first 4 days after receiving ketamine. The AGMs continued to display significantly reduced daily food intake on the fifth day after ketamine. The male rhesus macagues showed a trend toward reduced daily food intake, greatest during the first 2 days and remaining less than baseline intake through the fifth day following ketamine. The degree of observed food intake reduction was most severe at the 24 h (mean percent intake reduction: AGMs: 57%; rhesus males: 48%; rhesus females: 40%) and 48 h time points (AGMs: 24%; rhesus males: 14%; rhesus females: 13%). A subset of the AGMs that did not receive ketamine, but observed other animals in the room receive ketamine, showed reduced food intake at 24 and 48 h after ketamine, though not to the degree associated with ketamine administration. These results indicate that ketamine anesthesia is associated with a prolonged reduction in daily food intake in AGMs and rhesus macaques. Frequent use of ketamine in non-human primates may have a significant impact on animal health and well-being, and alternatives to its use warrant consideration. Am. J. Primatol. 69:1080–1092, 2007. Published 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Indian-origin rhesus macaques (Macaca mulatta) have long served as an animal model for the study of human disease and behavior. Given the current shortage of Indian-origin rhesus, many researchers have turned to rhesus macaques from China as a substitute. However, a number of studies have identified marked genetic differences between the Chinese and Indian animals. We investigated the genetic characteristics of a third rhesus population, the rhesus macaques of Nepal. Twenty-one rhesus macaques at the Swoyambhu Temple in Kathmandu, Nepal, were compared with more than 300 Indian- and Chinese-origin rhesus macaques. The sequence analyses of two mitochondrial DNA (mtDNA) loci, from the HVS I and 12 S rRNA regions, showed that the Nepali animals were more similar to Indian-origin than to Chinese-origin animals. The distribution of alleles at 24 short tandem repeat (STR) loci distributed across 17 chromosomes also showed greater similarity between the Nepali and Indian-origin animals. Finally, an analysis of seven major histocompatibility complex (MHC) alleles showed that the Nepali animals expressed Class I alleles that are common to Indian-origin animals, including Mamu-A*01. All of these analyses also revealed a low level of genetic diversity within this Nepali rhesus sample. We conclude that the rhesus macaques of Nepal more closely resemble rhesus macaques of Indian origin than those of Chinese origin. As such, the Nepali rhesus may offer an additional resource option for researchers who wish to maintain research protocols with animals that possess key genetic features characteristic of Indian-origin rhesus macaques. Am. J. Primatol. 68:1–11, 2006. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

This paper reports 20 new microsatellite loci that are highly polymorphic in rhesus macaques (Macaca mulatta). We screened known human microsatellite loci to identify markers that are polymorphic in rhesus macaques, and then selected specific loci that show substantial levels of heterozygosity and robust, reliable amplification. The 20 loci reported here were chosen to include one highly informative microsatellite from each rhesus monkey autosomal chromosome. Fourteen of the 20 polymorphisms are tetranucleotide repeats, and all can be analyzed using standard PCR and electrophoresis procedures. These new rhesus markers have an average of 15.5 alleles per locus and average heterozygosity of 0.83. This panel of DNA polymorphisms will be useful for a variety of different genetic analyses, including pedigree testing, paternity analysis, and population genetic studies. Many of these loci are also likely to be informative in other closely related Old World monkey species. Am. J. Primatol. 67:377–383, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Platelet-activating factor (PAF) is a potent signaling phospholipid that has been implicated in a number of biological activities. PAF concentration in primate spermatozoa has a positive correlation with fertility. While PAF is present in rhesus spermatozoa, there are no relational reports on its concentration and the cell’s motility. The study objective was to determine if PAF concentration in rhesus spermatozoa was correlated with motility indices (percent motility and forward progression). Semen was collected from sexually mature males and cell counts, and percent motilities and forward progressions were recorded prior to PAF measurement by radioimmunoassay. Spermatozoa-derived PAF concentration ranged from a low of 0.9 picomoles/10[sup 6] cells to a high of 13.0 picomoles/10[sup 6] cells. The overall mean (±SEM) PAF concentration was 4.6 (±1.6) picomoles/10[sup 6] spermatozoa. Regression analysis revealed a positive and significant relationship between PAF concentration in the spermatozoa and percent motility (R[sup 2] = 0.914; P < 0.01) as well as forward progression (R[sup 2] = 0.849; P < 0.05). A receiver-operator characteristic curve and the calculation of the probability that a positive forward progression will be predicted indicated a cutoff limit of 1.5 picomoles/10[sup 6] cells for PAF concentration in rhesus sperm. Rhesus monkey spermatozoa motility was significantly greater (P < 0.01) in the high-PAF (≥2 picomoles/10[sup 6] cells) group (31.0 ± 7.6) than in the low-PAF (<2 picomoles/10[sup 6] cells) group (6.8 ± 2.1). Rhesus monkey spermatozoa forward progression was significantly greater (P < 0.05) in the high-PAF (≥2 picomoles/10[sup 6] cells) group (3.0 ± 1.0) than in the low-PAF (<2 picomoles/10[sup 6] cells) group (0.7 ± 0.3). The data demonstrate that PAF concentration in rhesus spermatozoa has a significant relationship with percent motility and the cell’s forward progression. Determining PAF concentration in spermatozoa may be a significant predictor of fertility in the primate. Additional studies will elucidate the role of PAF in spermatozoa function and the significance PAF plays in primate fertility. Am. J. Primatol. 56:1–7, 2002. © 2002 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Linkage analysis can be problematic in humans because of the lack of large, multigenerational pedigrees and the difficulties in obtaining phenotypic data on all family members. In contrast, large, captive colonies of rhesus macaque are a potentially valuable resource for linkage studies because detailed phenotypic and genealogical data are kept, inbreeding is avoided, and DNA samples can usually be obtained. Microsatellite marker sets for genome-wide screening are available in a number of species, but not for the rhesus macaque. We tested primers to 400 human microsatellite markers from a genome-wide mapping set using DNA from nine unrelated female rhesus macaques. We found that 76 (19%) of the primers amplified a polymorphic product using the standard protocols for human DNA. The average heterozygosity of the markers in humans was 0.80, compared to 0.65 in the rhesus macaques. This study provides preliminary data, which could be used toward the development of a linkage mapping set in this species. There would be a need, however, to confirm the Mendelian inheritance of the markers. Am. J. Primatol. 54:223–231, 2001. © 2001 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

This study examined the reproductive performance of rhesus macaques maintained in two different housing conditions: high-density semi-sheltered gang cages and low-density outdoor corrals. Two hundred sixteen subjects were housed in 49 gang cages, each of which contained one breeding male and between one and eight breeding females. Two hundred seven subjects were housed in 13 corrals, each of which contained between two and four breeding males and between 9 and 26 breeding females. Over a 3-year period, pregnancy, live birth, and production rates were significantly greater for females in corrals than for females in gang cages. Fetal death rate was lower in corrals than in gang cages, while neonatal death rates did not differ between housing conditions. These differences did not result from potential confounds such as differential age structures or virological statuses between housing conditions. We conclude that, for rhesus macaques, outdoor corral housing leads to better reproductive performance than does semi-sheltered gang housing, probably as a result of increased individual space and relaxation of intense social stressors. Am. J. Primatol. 50:87–93, 2000. © 2000 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

A group of juvenile rhesus macaques (Macaca mulatta) living in a nuclear-family laboratory environment was studied to determine their responses to the births of siblings. The frequencies of interactions with family members (mothers, fathers, and new siblings) and nonfamily (peers, unrelated infants, and unrelated adults) were studied over both the year preceding and the year following sibling birth. The frequencies of specific behaviors in each of those interactions and the frequencies of interactions in each area of the nuclear-family unit (home cage, play area, or other families' cage) were also examined. After new siblings arrived, several measures of interactions with mothers, fathers, and new siblings increased significantly; by contrast inter-actions with peers decreased substantially over the post-birth year. Although the frequency of interactions in home cages remained stable over the 2-year period, interactions outside of the subjects' home cages decreased significantly after siblings were born. An additional subject group whose mothers became pregnant but failed to deliver viable offspring showed no significant changes in total levels of interactions with peers; they did, however, exhibit increases in some interactions with unrelated infants and adults. Female juveniles interacted with new siblings siginificantly more often than did males when siblings were less than 6 months old, but as siblings grew older (6-12 months), females' levels of interaction with them felt to a level equal to that of males. In the nuclear-family social structure, the birth of a sibling resulted in an increased emphasis on family interactions at the expense of peer interactions. [ABSTRACT FROM AUTHOR]

The study reported here examined the effect of different rearing conditions and psychological stress on immunoglobulin levels in rhesus monkey infants. In the first experiment, 24 rhesus neonates were placed in one of the three following rearing conditions: Separated from their mothers and reared in the laboratory nursery; kept with their biological mothers; or removed at birth from their biological mothers and cross-fostered to adoptive rhesus mothers. Plasma samples were obtained from the nursery-reared infants immediately after birth and at weekly intervals for the next 30 days. Samples were also obtained from mother-reared and foster-reared infants on days 15 and 29. All samples were tested for IgG and IgM levels. The results indicated that neither rearing nor diet affected Ig levels. IgG levels were highest at birth and decreased progressively for the first 30 days, suggesting that placental transfer of maternal IgG is the critical determinant of IgG levels in primate infants as in humans. IgM changes were also similar to those in human infants: Low levels at birth, a significant increase from birth to day 15, and a moderate decline from day 15 to day 30. When IgG levels and IgM levels were correlated across the filet month, many significant correlations were found which were consistent with human data relating both infant IgG and IgM levels to infant maturation. In the second experiment, 11 of the previously tested nursery infants were subjected to four consecutive social separations from peer groups at 6 months of age. Plasma samples were obtained before and after the first and fourth weeks of separation and tested for IgG and IgM levels. Small but significant decreases in both immunoglobulins were detected after 4 days of separation, particularly on the fourth week. [ABSTRACT FROM AUTHOR]

When rhesus monkeys are observed in social groups during the breeding season, increases in interfemale aggression coincide with midcycle increases in sexual activity between males and females. However, some investigators have suggested that both aggressive and affiliative interactions between females are influenced by the presence or absence of males, irrespective of menstrual cycle stage. In the present study, social interactions among members of a captive group of rhesus females were measured during the non- breeding season in response to the introduction of rhesus males. Ovariectomized rhesus females (estrogen-treated or untreated) served as stimulus controls. Tests with males were characterized by significantly decreased interfemale proximity and grooming and significantly increased aggression from that seen in tests with stimulus females or in the absence of stimulus animals. Only interfemale proximity declined significantly during stimulus female tests, but results suggest that this may merely reflect a decline in this behavior that occurs across the course of' the day. Estrogen treatment did not alter either the aggressive or affiliative behavior of stimulus females or group female response to stimulus females. The possibility is discussed that changes in interfemale interactions during tests with males reflect female interest in interacting with the male, particularly under social conditions that may limit such interactions. [ABSTRACT FROM AUTHOR]

This paper reports the results of an eight-year study of seasonal reproduction in the free-ranging colony of rhesus monkeys on Cayo Santiago, Puerto Rico. There was a significant correlation between the start of the annual spring rainy season and the estimated median conception date (r = .94, p < .001) and median birth date (r = .94, p < .001). Conceptions followed the commencement of spring rains by 70 days. Significant and negative correlations were found between the number of days from the start of the rains to the first conception (r = −.93, p < 0.01) and median conceptions (r = −.91, p < .01). When spring rains were delayed, the interval- between the onset of rains and conceptions decreased linearly. The median birth date for the Cayo Santiago population was accurately predicted for 1984 using two methods. When results from Cayo Santiago were applied retrospectively to data from the colony of rhesus monkeys near La Parguera, Puerto Rico, it explained the three-month difference in seasonality of reproduction between the two populations located at the same latitude (18°N). Photoperiod, as a function of latitude, appears to set the temporal limits of seasonal reproduction in rhesus macaques, while the onset of spring rains regulates reproductive activity within that range, at least in the Cayo Santiago population. The biological channel through which the effect is mediated has not been identified. [ABSTRACT FROM AUTHOR]