Comparison of Direct and Indirect Methods of Measuring Arterial Blood Pressure in Healthy, Anesthetized African Green Monkeys (Chlorocebus aethiops)

Quantitative blood pressure measurement is a critical parameter for assessing cardiovascular health, monitoring physiologic status under anesthesia, and making clinical decisions. The placement of an arterial catheter is the most accurate way to measure blood pressure, but is invasive and perhaps uncomfortable for the patient, requires sedation or anesthesia, and is technically challenging for staff. Noninvasive devices and methods, including oscillometry, high-definition oscillometry, and Doppler flow can be used to measure blood pressure. However, the American College of Veterinary Internal Medicine guidelines state that blood pressure should be measured using devices that have been validated in the species of interest and under the circumstances in which the measurement is being made. The alternatives listed above have not been validated in this manner. The objective of this study was to compare indirect ultrasonic Doppler flow detection and oscillometric blood pressure measures with direct arterial measurement in 8 healthy, anesthetized African green monkeys using the methods of Bland-Altman to assess agreement. Our results indicated that neither Doppler flow nor oscillometry consistently estimates direct blood pressure measurements in anesthetized African green monkeys. In 6 female monkeys, which weighed less than the 2 male subjects, the indirect Doppler measurement more closely predicted direct mean arterial pressure, indicating Dop- pler flow may be useful for monitoring mean arterial pressure in small patients.

Field data confirm the ability of a biophysical model to predict wild primate body temperature

In the face of climate change there is an urgent need to understand how animal performance is affected by environmental conditions. Biophysical models that use principles of heat and mass transfer can be used to explore how an animal's morphology, physiology, and behavior interact with its environment in terms of energy, mass and water balances to affect fitness and performance. We used Niche Mapper™ (NM) to build a vervet monkey (Chlorocebus pygerythrus) biophysical model and tested the model's ability to predict core body temperature (T_b) variation and thermal stress against T_b and behavioral data collected from wild vervets in South Africa. The mean observed T_b in both males and females was within 0.5 °C of NM's predicted T_bs for 91% of hours over the five-year study period. This is the first time that NM's T_b predictions have been validated against field data from a wild endotherm. Overall, these results provide confidence that NM can accurately predict thermal stress and can be used to provide insight into the thermoregulatory consequences of morphological (e.g., body size, shape, fur depth), physiological (e.g. T_b plasticity) and behavioral (e.g., huddling, resting, shade seeking) adaptations. Such an approach allows users to test hypotheses about how animals adapt to thermoregulatory challenges and make informed predictions about potential responses to environmental change such as climate change or habitat conversion. Importantly, NM's animal submodel is a general model that can be adapted to other species, requiring only basic information on an animal's morphology, physiology and behavior.

Reactions to infant death by wild vervet monkeys (Chlorocebus pygerythrus) in KwaZulu-Natal, South Africa: prolonged carrying, non-mother carrying, and partial maternal cannibalism

Observations of dead infant carrying have been reported for many primate species, and researchers have proposed several hypotheses to explain this behaviour. However, despite being a relatively well-studied species, reports of dead infant carrying in wild vervet monkeys (Chlorocebus pygerythrus) remain scarce. Here we report 14 observations of dead infant carrying by female vervet monkeys in a population at Mawana Game Reserve, KwaZulu-Natal, South Africa. Most of the females carried the dead infant for a day or less, but one female carried her infant for at least 14 days. In one case the maternal sister of a dead infant carried it after the death of their mother. We also report a case of mother-infant cannibalism: a female consumed part of her deceased infant's tail. Other post-mortem care-taking behaviours such as grooming, smelling and licking were also recorded. Of 97 recorded infant deaths in this study population since 2010, 14.4% are known to have elicited dead infant carrying, a proportion similar to that reported for other monkey species. We discuss our observations in relation to various hypotheses about this behaviour, including the post-parturition hormones hypothesis, learning to mother hypothesis, and unawareness of death hypothesis.

Anatomy of nerve fiber bundles at micrometer-resolution in the vervet monkey visual system

Although the primate visual system has been extensively studied, detailed spatial organization of white matter fiber tracts carrying visual information between areas has not been fully established. This is mainly due to the large gap between tracer studies and diffusion-weighted MRI studies, which focus on specific axonal connections and macroscale organization of fiber tracts, respectively. Here we used 3D polarization light imaging (3D-PLI), which enables direct visualization of fiber tracts at micrometer resolution, to identify and visualize fiber tracts of the visual system, such as stratum sagittale, inferior longitudinal fascicle, vertical occipital fascicle, tapetum and dorsal occipital bundle in vervet monkey brains. Moreover, 3D-PLI data provide detailed information on cortical projections of these tracts, distinction between neighboring tracts, and novel short-range pathways. This work provides essential information for interpretation of functional and diffusion-weighted MRI data, as well as revision of wiring diagrams based upon observations in the vervet visual system.

Correlates of social role and conflict severity in wild vervet monkey agonistic screams

Screams are acoustically distinct, high-pitched and high-amplitude calls, produced by many social species. Despite a wide range of production contexts, screams are characterised by an acoustic structure that appears to serve in altering the behaviour of targeted receivers during agonistic encounters. In chimpanzees, this can be achieved by callers producing acoustic variants that correlate with their identity, social role, relationship with the targeted recipient, the composition of the audience and the nature of the event. Although vervet monkeys (Chlorocebus pygerythrus) have been studied for decades, not much is known about their agonistic screams. Here, we examined agonistic screams produced by wild vervet monkeys to investigate the degree to which caller identity, social role and conflict severity affected call structure. We found that screams were both individually distinctive and dependent of the agonistic events. In particular, victim screams were longer and higher-pitched than aggressor screams, while screams produced in severe conflicts (chases, physical contact) had higher entropy than those in mild conflicts. We discuss these findings in terms of their evolutionary significance and suggest that acoustic variation might serve to reduce the aggression level of opponents, while simultaneously attracting potential helpers.

Hepatic Vitamin A Concentrations in Vervets (Chlorocebus aethiops) Supplemented with Carotenoids Derived from Oil Palm

Commonly used in biomedical research, vervets (Chlorocebus aethiops) are omnivorous but primarily meet their vitamin A requirements from provitamin A carotenoids. Hypervitaminosis A has occurred in vervets that consume feed high in preformed vitamin A. We investigated the vitamin A status of vervets supplemented daily with various antioxidants derived from palm oil. Male vervets (n = 40) were placed for 23 wk on a high-fat diet (34.9% energy) containing 645 μ g retinol activity equivalents (RAE), with 515 μ g RAE from preformed vitamin A. Vervets were randomized to 5 treatments (duration, 20 mo): control; 100 mg d-α-tocopheryl acetate; 100 mg oil palm (Elaeis guineensis)-derived vitamin E; 50 mg oil palm-derived vitamin E + 50 mg carotenoid complex + unrestricted palm-derived water-soluble antioxidants; and 5) unrestricted water-soluble antioxidants. Livers (n = 38) were analyzed for vitamin A, α-retinol (α-vitamin A), and carotenoids. Median hepatic vitamin A and total carotenoid concentrations were 6.49 μ mol/g and 4.30 nmol/g, respectively. Compared with controls, vervets fed the carotenoid complex had higher hepatic vitamin A (11.9 ± 5.1 μ mol/g), α -vitamin A (1.3 ± 0.7 μ mol/g), α -carotene (11.5 ± 5.3 nmol/g), β-carotene (15.6 ± 8.6 nmol/g), and total carotenoids (28.1 ± 13.9 nmol/g) but lower lutein (0.66 ± 0.28 nmol/g) and zeaxanthin (0.24 ± 0.06 nmol). NHP may benefit from replacement of preformed vitamin A with carotenoids in feeds; however, bioconversion efficiency in these models should be investigated to determine optimal levels.

Morphological variation in the genus Chlorocebus: Ecogeographic and anthropogenically mediated variation in body mass, postcranial morphology, and growth

OBJECTIVES

Direct comparative work in morphology and growth on widely dispersed wild primate taxa is rarely accomplished, yet critical to understanding ecogeographic variation, plastic local variation in response to human impacts, and variation in patterns of growth and sexual dimorphism. We investigated population variation in morphology and growth in response to geographic variables (i.e., latitude, altitude), climatic variables (i.e., temperature and rainfall), and human impacts in the vervet monkey (Chlorocebus spp.).

METHODS

We trapped over 1,600 wild vervets from across Sub-Saharan Africa and the Caribbean, and compared measurements of body mass, body length, and relative thigh, leg, and foot length in four well-represented geographic samples: Ethiopia, Kenya, South Africa, and St. Kitts & Nevis.

RESULTS

We found significant variation in body mass and length consistent with Bergmann's Rule in adult females, and in adult males when excluding the St. Kitts & Nevis population, which was more sexually dimorphic. Contrary to Rensch's Rule, although the South African population had the largest average body size, it was the least dimorphic. There was significant, although very small, variation in all limb segments in support for Allen's Rule. Females in high human impact areas were heavier than those with moderate exposures, while those in low human impact areas were lighter; human impacts had no effect on males.

CONCLUSIONS

Vervet monkeys appear to have adapted to local climate as predicted by Bergmann's and, less consistently, Allen's Rule, while also responding in predicted ways to human impacts. To better understand deviations from predicted patterns will require further comparative work in vervets.

Male monkeys use punishment and coercion to de-escalate costly intergroup fights

In numerous social species, males direct aggression towards female group members during intergroup fights, and this behaviour is commonly thought to function as mate guarding, even though males often target non-receptive females. In studying intergroup fights in a wild population of vervet monkeys, we found that male intragroup aggression was primarily directed towards individuals who had either just finished exhibiting, or were currently attempting to instigate intergroup aggression. Targeted females were less likely to instigate intergroup aggression in the future, indicating that male intragroup aggression functioned as coercion (when directed towards those who were currently trying to instigate a fight) and punishment (when directed towards those who had recently fought). These manipulative tactics effectively prevented intergroup encounters from escalating into fights and often de-escalated ongoing conflicts. Males who were likely sires were those most likely to use punishment/coercion, particularly when they were wounded, and, therefore, less able to protect vulnerable offspring should a risky intergroup fight erupt. This work, along with our previous finding that females use punishment and rewards to recruit males into participating in intergroup fights, highlights the inherent conflict of interest that exists between the sexes, as well as the role that social incentives can play in resolving this conflict. Furthermore, unlike other studies which have found punishment to be used asymmetrically between partners, these works represent a novel example of reciprocal punishment in a non-human animal.

Vervet monkey (Chlorocebus pygerythrus) behavior in a multi-destination route: Evidence for planning ahead when heuristics fail

Animal paths are analogous to intractable mathematical problems like the Traveling Salesman Problem (TSP) and the shortest path problem (SPP). Both the TSP and SPP require an individual to find the shortest path through multiple targets but the TSP demands a return to the start, while the SPP does not. Vervet monkeys are very efficient in solving TSPs but this species is a multiple central place forager that does not always return to the same sleeping site and thus theoretically should be selected to find solutions to SPPs rather than TSPs. We examined path choice by wild vervets in an SPP experimental array where the shortest paths usually differed from those consistent with common heuristic strategies, the nearest-neighbor rule (NNR-go to the closest resource that has not been visited), and the convex hull (put a mental loop around sites, adding inner targets in order of distance from the edge)-an efficient strategy for TSPs but not SPPs. In addition, humans solving SPPs use an initial segment strategy (ISS-choose the straightest path at the beginning, only turning when necessary) and we looked at vervet paths consistent with this strategy. In 615 trials by single foragers, paths usually conformed to the NNR and rarely the slightly more efficient convex hull, supporting that vervets may be selected to solve SPPs. Further, like humans solving SPPs, vervets showed a tendency to use the ISS. Paths consistent with heuristics dropped off sharply, and use of the shortest path increased, when heuristics led to longer paths showing trade-offs in efficiency versus cognitive load. Two individuals out of 17, found the shortest path most often, showing inter-individual variation in path planning. Given support for the NNR and the ISS, we propose a new rule-of-thumb termed the "region heuristic" that vervets may apply in multi-destination routes.

Female vervet monkeys fine-tune decisions on tolerance versus conflict in a communication network

Group living promotes opportunities for both cooperation and competition. Selection on the ability to cope with such opposing social opportunities has been proposed as a driving force in the evolution of large brains in primates and other social species. However, we still know little about the degree of complexity involved in such social strategies. Here, we report advanced social strategies in wild vervet monkeys. Building on recent experimental evidence that subordinate females trade grooming for tolerance from higher-ranking individuals during foraging activities, we show that the audience composition strongly affects this trade. First, tolerance was lower if the audience contained individuals that outranked the subordinate partner, independently of audience size and kinship relationships. Second, we found a significant interaction between previous grooming and relative rank of bystanders: dominant subjects valued recent grooming by subordinates while intermediate ranked subjects valued the option to aggress subordinate partners in the presence of a dominant audience. Aggressors were also more likely to emit coalition recruitment calls if the audience contained individuals that outranked the subordinate partner. In conclusion, vervet monkeys include both recent grooming and knowledge about third-party relationships to make complex decisions when trading grooming for tolerance, leading to a finely balanced trade-off between reciprocation and opportunities to reinforce rank relationships.

Comparison of Saliva Collection Methods for the Determination of Salivary Cortisol Levels in Rhesus Macaques (Macaca mulatta), Cynomolgus Macaques (Macaca fascicularis), and African Green Monkeys (Chlorocebus aethiops)

The ability to quickly and accurately determine cortisol as a biomarker for stress is a valuable tool in assessing the wellbeing of NHP. In this study, 2 methods of collecting saliva (a commercial collection device and passive drool) and the resulting free salivary cortisol levels were compared with total serum cortisol concentration in rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis) and African green monkeys (Chlorocebus aethiops) at 2 collection time points. Serum and salivary cortisol levels were determined using a competitive quantitative ELISA. In addition, both saliva collection methods were evaluated for volume collected and ease of use. Compared with passive drool, the experimental collection device was more reliable in collecting sufficient volumes of saliva, and the resulting salivary cortisol values demonstrated stronger correlation with serum cortisol concentration in all species and collection days except cynomolgus macaques on day 1. This saliva collection device allows quick and reliable sample collection for the determination of salivary cortisol levels. In addition, the results might provide a useful tool for evaluating hypothalamic-pituitary-adrenal axis activity or the physiologic stress reaction in NHP as well as a biomarker of psychologic stress states in a variety of situations.

Reduced Intestinal Motility, Mucosal Barrier Function, and Inflammation in Aged Monkeys

OBJECTIVE

We aimed to examine the general health and intestinal physiology of young and old non-human primates with comparable life histories and dietary environments.

DESIGN

Vervet monkeys (Chlorcebus aethiops sabaeus) in stable and comparable social and nutritional environments were selected for evaluation. Health phenotype, circulating cytokines and biomarkers of microbial translocation (MT) were measured (n=26-44). Subsets of monkeys additionally had their intestinal motility, intestinal permeability, and fecal microbiomes characterized. These outcomes document age-related intestinal changes present in the absence of nutritional stressors, which are all known to affect gastrointestinal motility, microbiome, and MT.

RESULTS

We found that old monkeys have greater systemic inflammation and poor intestinal barrier function as compared to young monkeys. Old monkeys have dramatically reduced intestinal motility, and all changes in motility and MT are present without large differences in fecal microbiomes.

CONCLUSION

We conclude that deteriorating intestinal function is a feature of normal aging and could represent the source of inflammatory burden yet to be explained by disease or diet in normal aging human primate populations. Intestinal changes were seen independent of dietary influences and aging within a consistent environment appears to avoid major microbiome shifts. Our data suggests interventions to promote intestinal motility and mucosal barrier function have the potential to support better health with aging.

Male food defence as a by-product of intersexual cooperation in a non-human primate

Males in a number of group-living species fight in intergroup conflicts to defend access to food resources, a seemingly paradoxical behaviour, given that this resource does not usually limit male fitness directly. We investigated the mechanism(s) driving apparent male food defence in wild vervet monkeys (Chlorocebus aethiops pygerythrus) by testing the effect that female resource access, and female audience size and activity had on the response of focal males during simulated intergroup encounters. Males do not appear to defend food to increase the reproductive success of female group members because their response was not influenced by the presence of provisioning boxes that only females could access. Female audience size was also unimportant, suggesting males do not participate in intergroup encounters to advertise their quality to potential mates. However, focal males almost always followed/supported female group members who initiated an approach towards simulated intruders, supporting that male participation largely functions to gain status as a cooperative group member, and that apparent male food defence in this species arises as a by-product of intersexual cooperation. Our study highlights that considering audience composition and activity can reveal the presence of social incentives and illuminate the evolutionary mechanism(s) promoting joint action in intergroup aggression.

A comparison of adult body size between captive and wild vervet monkeys (Chlorocebus aethiops sabaeus) on the island of St. Kitts

Weight and 34 morphological measurements were obtained from 103 vervet monkeys living either in the wild or in captive colonies derived from the wild populations on the island of St. Kitts in the Eastern Caribbean. All measures were taken during the same week, eliminating bias that might result from changing seasonal environmental conditions. Vervets on St. Kitts are all descended from a small number of individuals brought to the island approximately 400 years ago from West Africa, thus eliminating bias that might result from subspecific size differences. We conducted a principal components analysis (PCA) and compared individual traits between captive and wild adult animals. Morphological measures such as body, arm, and leg length did not differ significantly between animals living in the wild and animals in captivity. Weight and measures indicating condition-including body mass index (BMI), chest, thigh, and upper arm girth were all higher for animals living in captivity. More consistent available food is probably the cause of differences in measures reflecting condition.

Characterization of ovarian aging and reproductive senescence in vervet monkeys (Chlorocebus aethiops sabaeus)

Female vervet monkeys (Chlorocebus aethiops sabaeus) are used as an experimental model for chronic diseases relevant to women's health. However, reproductive senescence (menopause) has not yet been characterized for vervet monkeys. Here we describe the histologic, hormonal, and menstrual markers of reproductive senescence in vervet monkeys from the Wake Forest Vervet Research Colony. Ovaries from monkeys (age, 0 to 27 y) were serially sectioned (5 μm), stained, and photographed. In every 100th section, the numbers of primordial, primary, and secondary follicles were determined, and triplicate measurements were used to calculate mean numbers of follicles per ovary. Antimüllerian hormone (AMH), follicle stimulating hormone, and menstrual cycle length were measured in additional monkeys. Primordial follicles and AMH decreased significantly with age, and significant correlations between numbers of primordial and primary follicles and between numbers of primary and secondary follicles were noted. Histologic evaluation revealed that ovaries from 4 aged monkeys (older than 23 y) were senescent. One aged monkey transitioned to menopause, experiencing cycle irregularity over 4 y, eventual cessation of menses, and plasma AMH below the level of detection. Finally, with increasing age, the percentage of female vervets with offspring declined significantly. The present study provides insight into ovarian aging and reproductive senescence in vervet monkeys. Results highlight the importance of considering this nonhuman primate as a model to investigate the relationships between ovarian aging and chronic disease risk.

Assessing the pulsatility of luteinizing hormone in female vervet monkeys (Chlorocebus aethiops sabaeus)

Specific alterations in the pulsatility of luteinizing hormone (LH) are linked to obesity-related subfertility in ovulatory women. Vervet monkeys (Chlorocebus aethiops sabaeus) are an Old World nonhuman primate that develops obesity and has a menstrual cycle similar to humans. We evaluated follicular-phase LH pulses in 12 adult normal-weight female vervets. Serum was collected every 10 min for 4 h by using a tether device in conscious, freely moving monkeys on menstrual cycle days 2 through 5. Serum estradiol was collected daily during the follicular phase to identify the luteal-follicular transition. For comparison, we used data from 12 ovulatory normal-weight women who had undergone frequent blood sampling of early-follicular LH. LH pulse frequency was similar, with 2.8 ± 0.7 LH pulses during 4 h in vervets compared with 2.3 ± 0.7 LH pulses during 4 h in women. The LH pulse mass (percentage change in the pulse peak over the preceding nadir) was 123.2% ± 27.4% in vervets and 60.9% ± 14.9% in humans. The first day of low serum estradiol after the follicular-phase peak was denoted as the day of the luteal-follicular transition. Luteectomy was performed on luteal days 7 through 9, and corpora lutea were confirmed by histology. We demonstrate that follicular LH patterns in vervets are similar to those in humans and that the luteal phase is easily identified by monitoring daily serum estradiol. These findings demonstrate that vervet monkeys are a suitable animal model for evaluating LH pulse dynamics longitudinally in studies of diet-induced obesity.

Third-party ranks knowledge in wild vervet monkeys (Chlorocebus aethiops pygerythrus)

The Machiavellian/Social Intelligence Hypothesis proposes that a complex social environment selected for advanced cognitive abilities in vertebrates. In primates it has been proposed that sophisticated social strategies like obtaining suitable coalition partners are an important component of social intelligence. Knowing the rank relationships between group members is a basic requirement for the efficient use of coalitions and the anticipation of counter-coalitions. Experimental evidence for such knowledge currently exists in only few species. Here, we conducted rank reversal playback experiments on adult females belonging to three different groups of free-ranging vervet monkeys (Chlorocebus aethiops pygerythrus) to test their knowledge of the female hierarchy. Playbacks simulating rank reversals (subordinate aggressing a dominant) induced longer looking times than playbacks simulating a dominant aggressing a subordinate. Vervet monkey females therefore seem to compute the rank relationships between other females. Our results suggest that detailed social knowledge about rank relationships may be widespread in primates and potentially also in other species living in stable groups.

Planum temporale grey matter asymmetries in chimpanzees (Pan troglodytes), vervet (Chlorocebus aethiops sabaeus), rhesus (Macaca mulatta) and bonnet (Macaca radiata) monkeys

Brain asymmetries, particularly asymmetries within regions associated with language, have been suggested as a key difference between humans and our nearest ancestors. These regions include the planum temporale (PT) - the bank of tissue that lies posterior to Heschl's gyrus and encompasses Wernicke's area, an important brain region involved in language and speech in the human brain. In the human brain, both the surface area and the grey matter volume of the PT are larger in the left compared to right hemisphere, particularly among right-handed individuals. Here we compared the grey matter volume and asymmetry of the PT in chimpanzees and three other species of nonhuman primate in two Genera including vervet monkeys (Chlorocebus aethiops sabaeus), rhesus macaques (Macaca mulatta) and bonnet macaques (Macaca radiata). We show that the three monkey species do not show population-level asymmetries in this region whereas the chimpanzees do, suggesting that the evolutionary brain development that gave rise to PT asymmetry occurred after our split with the monkey species, but before our split with the chimpanzees.

Supply and demand determine the market value of food providers in wild vervet monkeys

Animals neither negotiate verbally nor conclude binding contracts, but nevertheless regularly exchange goods and services without overt coercion and manage to arrive at agreements over exchange rates. Biological market theory predicts that such exchange rates fluctuate according to the law of supply and demand. Previous studies showed that primates pay more when commodities become scarcer: subordinates groomed dominants longer before being tolerated at food sites in periods of shortage; females groomed mothers longer before obtaining permission to handle their infants when there were fewer newborns and males groomed fertile females longer before obtaining their compliance when fewer such females were present. We further substantiated these results by conducting a 2-step experiment in 2 groups of free-ranging vervet monkeys in the Loskop Dam Nature Reserve, South Africa. We first allowed a single low-ranking female to repeatedly provide food to her entire group by triggering the opening of a container and measured grooming bouts involving this female in the hour after she made the reward available. We then measured the shifts in grooming patterns after we added a second food container that could be opened by another low-ranking female, the second provider. All 4 providers received more grooming, relative to the amount of grooming they provided themselves. As biological market theory predicts, the initial gain of first providers was partially lost again after the introduction of a second provider in both groups. We conclude that grooming was fine-tuned to changes in the value of these females as social partners.

Heterochrony and cross-species intersensory matching by infant vervet monkeys

BACKGROUND

Understanding the evolutionary origins of a phenotype requires understanding the relationship between ontogenetic and phylogenetic processes. Human infants have been shown to undergo a process of perceptual narrowing during their first year of life, whereby their intersensory ability to match the faces and voices of another species declines as they get older. We investigated the evolutionary origins of this behavioral phenotype by examining whether or not this developmental process occurs in non-human primates as well.

METHODOLOGY/PRINCIPAL FINDINGS

We tested the ability of infant vervet monkeys (Cercopithecus aethiops), ranging in age from 23 to 65 weeks, to match the faces and voices of another non-human primate species (the rhesus monkey, Macaca mulatta). Even though the vervets had no prior exposure to rhesus monkey faces and vocalizations, our findings show that infant vervets can, in fact, recognize the correspondence between rhesus monkey faces and voices (but indicate that they do so by looking at the non-matching face for a greater proportion of overall looking time), and can do so well beyond the age of perceptual narrowing in human infants. Our results further suggest that the pattern of matching by vervet monkeys is influenced by the emotional saliency of the Face+Voice combination. That is, although they looked at the non-matching screen for Face+Voice combinations, they switched to looking at the matching screen when the Voice was replaced with a complex tone of equal duration. Furthermore, an analysis of pupillary responses revealed that their pupils showed greater dilation when looking at the matching natural face/voice combination versus the face/tone combination.

CONCLUSIONS/SIGNIFICANCE

Because the infant vervets in the current study exhibited cross-species intersensory matching far later in development than do human infants, our findings suggest either that intersensory perceptual narrowing does not occur in Old World monkeys or that it occurs later in development. We argue that these findings reflect the faster rate of neural development in monkeys relative to humans and the resulting differential interaction of this factor with the effects of early experience.

The effect of harp music on heart rate, mean blood pressure, respiratory rate, and body temperature in the African green monkey

BACKGROUND

The effectiveness of recorded harp music as a tool for relaxation for non-human primates is explored in this study.

METHODS

Konigsberg Instruments Model T27F-1B cardiovascular telemetry devices were implanted into nine African green monkeys (Chlorocebus aethiops). After post-surgical recovery, animals were exposed to recorded harp music. Telemetry data were collected on heart rate, mean blood pressure, respiratory rate, and body temperature for a 30-minute baseline period before music exposure; a 90-minute period of music exposure; and a 90-minute post-exposure period, where no music was played.

RESULTS

No statistical differences were noted in heart rate, mean blood pressure, respiratory rate, and body temperature between pre-exposure, exposure, and post-exposure periods.

CONCLUSIONS

The lack of response in these African green monkeys may be attributable to their generally calm demeanor in captivity; experiments with a more excitable species such as the rhesus macaque might demonstrate a significant relaxation response to music.

Assessment of menstruation in the vervet (Cercopithecus aethiops)

Vervet monkeys (Chlorocebus aethiops) are Old World nonhumans that display attenuated menstruation that requires detection by vaginal swab. The physiology underlying attenuated menstruation in this species has not been previously studied. To fill this gap, we evaluated endometrial cell proliferation, steroid receptor localization and expression of menstruation-associated matrix metalloproteinase (MMP) enzymes in vervets during natural and artificial menstrual cycles. The artificial cycles were induced by sequentially treating ovariectomized animals with estradiol (E(2)) and progesterone (P). Because menstrual flow is exceptionally light in this species, menses was detected by vaginal swab. We found that both natural and artificially cycled animals menstruated 3-5 days after the decline of P at the end of the cycle. As in other primates, P withdrawal at the end of artificial cycles triggered endometrial expression of MMPs, including MMP-1, 2, 3, 7, 10, 11, 13 and 26 transcripts. In both the natural and artificial menstrual cycle, menstrual sloughing was restricted to the upper one-fourth of the endometrium, and MMP-1 and 2 were strongly expressed by the stroma of the sloughing zone. MMP-7 was localized in the endometrial glands during late menses. As in macaques, epithelial cell proliferation was localized to the functionalis zone during the estrogen-dominated proliferative phase and to the basalis zone glands during the P-dominated secretory phase. Regulation of estrogen and progestin (or estradiol and progesterone) receptors was similar to that reported for macaques. Because strong similarities exist between the endometrium of vervets, macaques and women, we conclude that vervets can provide a useful animal model for studies on hormone regulation of menstruation.

Immunolabelling of the 5-HT3B receptor subunit in the central and peripheral nervous systems in rodents

The 5-HT(3) receptor is a member of the superfamily of neurotransmitter-gated ion channels involved in fast synaptic signalling and in modulation of neurotransmitter release. As for many other channel receptors, the electrophysiological properties and the functions of the 5-HT(3) receptor are determined by subunit composition of the pentameric channel. Because in situ hybridization did not allow the detection of mRNA encoding the 5-HT(3B) subunit in the rodent central nervous system, or in nearly half of the neurons expressing the 5-HT(3A) subunit in peripheral ganglia, it has been suggested that subunit composition could define at least two 5-HT(3) receptor-expressing neuronal populations. In order to challenge this hypothesis, we have developed polyclonal antibodies directed against a portion of the second intracytoplasmic loop of the mouse 5-HT(3B) subunit. Immunohistochemical analysis in the mouse and the rat revealed that immunolabelling was most prominent in peripheral ganglia, particularly in trigeminal ganglia (TG). In rats, transection or ligature of the infraorbital nerve resulted in a pronounced accumulation of immunoreactive material at the proximal side of the lesioned nerve, and an up-regulation of both subunits in 5-HT(3) receptor-expressing TG neurons. Surprisingly, nearly 100% of neurons expressing 5-HT(3A) subunits were also labelled by anti-5-HT(3B) antibodies. We also detected 5-HT(3B) immunoreactivity in the rat hippocampal CA1 layer and in scattered cortical neurons, indicating that detection of 5-HT(3) subunit mRNA by in situ hybridization might not provide really complete mapping of heteromeric 5-HT(3A/B) vs. homomeric 5-HT(3A) receptors in the peripheral and central nervous systems in rodents.

Effects of three mydriatic drug regimens on pupil size in rhesus (Macaca mulatta) and African green monkeys (Chlorocebus aethiops)

BACKGROUND

Human mydriatric drug use in non-human primates (NHPs) has been documented but not quantified and compared for effectiveness. The objective of this study was to determine which drug regimen provided the most effective and consistent mydriatic effect for ophthalmologic examinations and other procedures. Secondary objectives were to determine average time to maximum dilation and whether species differences existed.

METHODS

Twelve rhesus and 12 African green monkeys were randomly assigned to one of six treatment combinations to test the mydriatic effects of three drug regimens: (1) tropicamide 1% (T); (2) tropicamide 1% and phenylephrine hydrochloride 2.5% (TP); and (3) tropicamide 1%, phenylephrine HCL 2.5% and cyclopentolate 1% (TPC). Left and right eyes of each monkey received a different drug regimen, depending on random assignment.

RESULTS

TPC showed a significantly larger mydriatic response in both species than T alone. Average time to maximum dilation with all three drug regimens was 50-60 minutes. Rhesus had a larger response to the mydriatic drug regimens than the African green monkeys.

CONCLUSIONS

The TPC regimen had the largest and longest lasting mydriatic effect in both species.

Vervet monkeys and humans show brain asymmetries for processing conspecific vocalizations, but with opposite patterns of laterality

A robust finding in the human neurosciences is the observation of a left hemisphere specialization for processing spoken language. Previous studies suggest that this auditory specialization and brain asymmetry derive from a primate ancestor. Most of these studies focus on the genus Macaca and all demonstrate a left hemisphere bias. Due to the narrow taxonomic scope, however, we lack a sense of the distribution of this asymmetry among primates. Further, although the left hemisphere bias appears mediated by conspecific calls, other possibilities exist including familiarity, emotional relevance and more general acoustic properties of the signal. To broaden the taxonomic scope and test the specificity of the apparent hemisphere bias, we conducted an experiment on vervets (Cercopithecus aethiops)-a different genus of old world monkeys and implemented the relevant acoustic controls. Using the same head orienting procedure tested with macaques, results show a strong left ear/right hemisphere bias for conspecific vocalizations (both familiar and unfamiliar), but no asymmetry for other primate vocalizations or non-biological sounds. These results suggest that although auditory asymmetries for processing species-specific vocalizations are a common feature of the primate brain, the direction of this asymmetry may be relatively plastic. This finding raises significant questions for how ontogenetic and evolutionary forces have impacted on primate brain evolution.

Ultrastructure and origin of membrane vesicles associated with the severe acute respiratory syndrome coronavirus replication complex

The RNA replication complexes of mammalian positive-stranded RNA viruses are generally associated with (modified) intracellular membranes, a feature thought to be important for creating an environment suitable for viral RNA synthesis, recruitment of host components, and possibly evasion of host defense mechanisms. Here, using a panel of replicase-specific antisera, we have analyzed the earlier stages of severe acute respiratory syndrome coronavirus (SARS-CoV) infection in Vero E6 cells, in particular focusing on the subcellular localization of the replicase and the ultrastructure of the associated membranes. Confocal immunofluorescence microscopy demonstrated the colocalization, throughout infection, of replicase cleavage products containing different key enzymes for SARS-CoV replication. Electron microscopy revealed the early formation and accumulation of typical double-membrane vesicles, which probably carry the viral replication complex. The vesicles appear to be fragile, and their preservation was significantly improved by using cryofixation protocols and freeze substitution methods. In immunoelectron microscopy, the virus-induced vesicles could be labeled with replicase-specific antibodies. Opposite to what was described for mouse hepatitis virus, we did not observe the late relocalization of specific replicase subunits to the presumed site of virus assembly, which was labeled using an antiserum against the viral membrane protein. This conclusion was further supported using organelle-specific marker proteins and electron microscopy. Similar morphological studies and labeling experiments argued against the previously proposed involvement of the autophagic pathway as the source for the vesicles with which the replicase is associated and instead suggested the endoplasmic reticulum to be the most likely donor of the membranes that carry the SARS-CoV replication complex.

Specialization in pyramidal cell structure in the sensory-motor cortex of the Chacma baboon (Papio ursinus) with comparative notes on macaque and vervet monkeys

The systematic study of pyramidal cell structure has revealed new insights into specialization of the phenotype in the primate cerebral cortex. Regional specialization in the neuronal phenotype may influence patterns of connectivity and the computational abilities of the circuits they compose. The comparative study of pyramidal cells in homologous cortical areas is beginning to yield data on the evolution and development of such specialized circuitry in the primate cerebral cortex. Recently, we have focused our efforts on sensory-motor cortex. Based on our intracellular injection methodology, we have demonstrated a progressive increase in the size of, the branching structure in, and the spine density of the basal dendritic trees of pyramidal cells through somatosensory areas 3b, 1, 2, 5, and 7 in the macaque and vervet monkeys. In addition, we have shown that pyramidal cells in premotor area 6 are larger, more branched, and more spinous than those in the primary motor cortex (MI or area 4) in the macaque monkey, vervet monkey, and baboon. Here we expand the basis for comparison by studying the basal dendritic trees of layer III pyramidal cells in these same sensory-motor areas in the chacma baboon. The baboon was selected because it has a larger cerebral cortex than either the macaque or vervet monkeys; motor cortex has expanded disproportionately in these three species; and motor cortex in the baboon reportedly has differentiated to include a new cortical area not present in either the macaque or vervet monkeys. We found, as in monkeys, a progressive increase in the morphological complexity of pyramidal cells through areas 3b, 5, and 7, as well as from area 4 to area 6, suggesting that areal specialization in microcircuitry was likely to be present in a common ancestor of primates. In addition, we found subtle differences in the extent of the interareal differences in pyramidal cell structure between homologous cortical areas in the three species.

Specialization in pyramidal cell structure in the cingulate cortex of the Chacma baboon (Papio ursinus): An intracellular injection study of the posterior and anterior cingulate gyrus with comparative notes on the macaque and vervet monkeys

This study forms part of an ongoing investigation of pyramidal cell structure in the cingulate cortex of primates. Recently we have demonstrated that layer III pyramidal cells in the anterior cingulate gyrus are considerably larger, more branched and more spinous than those in the posterior cingulate gyrus (areas 24 and 23, respectively) in the macaque and vervet monkeys. Moreover, the extent of the interareal difference in specialization in pyramidal cell structure differed between the two species. These data suggest that pyramidal cell circuitry may have evolved differently in these closely related species. Presently there are too few data to speculate on what is selecting for this specialization in structure. Here we extend the basis for comparison by studying pyramidal cell structure in cingulate gyrus of the Chacma baboon (Papio ursinus). Methodology used here is the same as that for our previous studies: intracellular injection of Lucifer Yellow in flat-mounted cortical slices. We found that pyramidal cells in anterior cingulate gyrus (area 24) were more branched and more spinous than those in posterior cingulate gyrus (area 23). Moreover, the complexity in pyramidal cell structure in both the anterior and posterior cingulate gyrus of the baboon differed to that in the corresponding regions in either the macaque or vervet monkeys.

Patchy organization and asymmetric distribution of the neural correlates of face processing in monkey inferotemporal cortex

BACKGROUND

It is believed that a face-specific system exists within the primate ventral visual pathway that is separate from a domain-general nonface object coding system. In addition, it is believed that hemispheric asymmetry, which was long held to be a distinct feature of the human brain, can be found in the brains of other primates as well. We show here for the first time by way of a functional imaging technique that face- and object-selective neurons form spatially distinct clusters at the cellular level in monkey inferotemporal cortex. We have used a novel functional mapping technique that simultaneously generates two separate activity profiles by exploiting the differential time course of zif268 mRNA and protein expression.

RESULTS

We show that neurons activated by face stimulation can be visualized at cellular resolution and distinguished from those activated by nonface complex objects. Our dual-activity maps of face and object selectivity show that face-selective patches of various sizes (mean, 22.30 mm2; std, 32.76 mm2) exist throughout the IT cortex in the context of a large expanse of cortical territory that is responsive to visual objects.

CONCLUSIONS

These results add to recent findings that face-selective patches of various sizes exist throughout area IT and provide the first direct anatomical evidence at cellular resolution for a hemispheric asymmetry in favor of the right hemisphere. Together, our results support the notion that human and monkey brains share a similarity in both anatomical organization and distribution of function with respect to high-level visual processing.

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

The brain requires internal or external reference frames to determine body orientation in space. These frames may change, however, to meet changing conditions. During quadrupedal overground locomotion by monkeys, the head rotates on a stabilized trunk during walking, but the trunk rotates on a stabilized head during galloping. Do the same movement patterns occur during in-place locomotion? Head and trunk pitch rotations were measured, and yaw and roll rotations estimated from cine films of three adult vervet monkeys(Cercopithecus aethiops L. 1758) walking and galloping quadrupedally on a treadmill. Head and trunk rotational patterns during treadmill walks were comparable to the patterns found during overground walks. The rotational velocities of these segments during both treadmill walks and gallops were also comparable to the velocities found during natural locomotion. By contrast,whereas head and trunk rotational patterns during treadmill gallops did occur that were comparable to the patterns practiced during overground gallops, a significantly different pattern involving large and simultaneous head and trunk rotations was more commonly observed. Simultaneous head and trunk rotations may be possible during treadmill gallops because the fixed visual surround is providing an adequate spatial reference frame. Alternatively, or in addition to this visual information, a re-weighting in other sensory modalities may be occurring. Specifically, the vestibular inputs used during overground locomotion to reference gravity or a gravity-derived vector may become less important than proprioceptive inputs that are using the treadmill belt surface as a reference. Regardless, the spatial reference frame being used, blinks that occur at specific times during the largest head yaw rotations may be necessary to avoid the initiation of unwanted and potentially destabilizing lateral sway brought on by sudden increases in optic flow velocity.

Adolescent impulsivity predicts adult dominance attainment in male vervet monkeys

Adolescence is characterized by behavioral and physiological changes that prepare individuals for the transition to adulthood. The purpose of this study was to evaluate the effects of behavioral, morphological, neurobiological, and developmental characteristics of adolescent male vervets in predicting later dominance attainment. Thirty-six adolescent male vervets were tested for social impulsivity by means of the Intruder Challenge test while they were still living in their natal groups. Body weight and cerebrospinal fluid (CSF) metabolites of serotonin, dopamine, and norepinephrine were measured before they were introduced into new matrilineal breeding groups at age 5. Stable adult dominance rank was determined at age 6, 1 year following introduction. The results indicated that body weight, adolescent impulsivity, and levels of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in CSF predicted adult dominance attainment. As expected, males that were above average in body weight prior to introduction were significantly more likely to become dominant. Males that were high in impulsivity as adolescents, and low in 5-HIAA prior to introduction were more likely to achieve stable alpha male status 1 year following introduction. The combination of these three factors resulted in correct prediction of rank attainment for 92% (33/36) of the males. Two other factors-maternal dominance rank and a measure of social anxiety from the Intruder Challenge test-were not related to adult dominance attainment in this sample. These results support the idea that there are benefits of a high-risk, high-gain strategy is beneficial for adolescent and young adult male vervets. They also demonstrate that adolescent impulsivity is age-limited. Males that achieved high rank moderated their behavior as adults, and no longer scored high in impulsivity relative to their age peers.

Fostering procedures for orphaned infants in a breeding colony of African green monkeys

We developed procedures to foster orphaned African green monkey infants to females with natural infants of a similar age to the foster infant (< 1 month). Our purpose was to assess the feasibility of fostering additional infants to females with natural infants. The subjects were 4 infants (age 1 to 5 days) that were removed from the natural mother because of neglect or trauma. The recipient females varied in parity (0 to 7 previous infants). Within 24 h of removal from the natural mother, the foster infants were presented to a group of potential recipient females by placing the foster infant directly into the cage of the female that demonstrated positive behavior toward the foster infant (reaching toward the infant and lip-smacking). Analysis of the behavioral data collected when the infants were 3 to 6 months of age indicated that foster mothers spent significantly more time nursing the natural infant alone, but the percentage time spent nursing both infants simultaneously was not significantly different than the time spent nursing either infant individually. No significant differences between weaning weight of the natural and foster infants or single infants were observed at 6 months of age. Overall our success rate at weaning (75%) suggests that fostering additional infants on females with a natural infant may be a viable strategy for raising orphaned African green monkeys and may prevent the development of abnormal behaviors that typically are manifested by nursery-reared infants.

PHYSIOLOGIC MANIFESTATIONS OF STRESS FROM CAPTURE AND RESTRAINT OF FREE-RANGING MALE AFRICAN GREEN MONKEYS (CERCOPITHECUS AETHIOPS)

Adrenal gland weights, stomach mucosal lesions, and morning serum cortisol and prolactin levels were measured in 15 juvenile and adult male African green monkeys (Cercopithecus aethiops) that were shot by a hunter, euthanized after 24 hr of captivity, or euthanized after 45 days of captivity and intermittent blood sampling. Hormone levels were measured in seven additional males that had been in captivity for 7 mo. Mean serum cortisol concentrations were significantly lower in free-ranging wild monkeys at the time they were shot than in the monkeys after 1 day in captivity. Cortisol concentrations were significantly higher in wild-caught monkeys on the day after capture than they were in the same animals after 18 and 26 days of captivity. Cortisol concentrations were also significantly higher in the wild-caught monkeys 18 days after capture than in the laboratory-habituated monkeys in captivity for 7 mo. Mean prolactin concentration was significantly lower in the wild-caught monkeys on day 2 after capture, and the levels increased gradually to 45 days in captivity and was highest in monkeys that had been captive for 7 mo.

Difference in food selection between patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus) in Kala Maloue National Park, Cameroon, in relation to nutrient content

Phytochemical or nutrient analyses of primate diets have revealed clues to their food selection in a single species. On the other hand, few interspecific comparisons of phytochemical or nutrient composition of primate diets have been made, although diets are considered to differ in phytochemical or nutrient content from primate species to species, since different species have different body weights and different morphological and physiological characteristics. I compared the nutrient content of diet between patas monkeys ( Erythrocebus patas) and tantalus monkeys ( Cercopithecus aethiops tantalus) living sympatrically in Cameroon. Patas subsisted on a smaller number of food items, most of which were also tantalus food items. Then, I compared the protein-fiber ratio and the available energy content of the food items eaten by patas (patas foods) with those items eaten only by tantalus (tantalus foods). Both variables were higher in patas than tantalus foods, although there was no significant difference in available energy of plant foods. Next, when I performed discriminant analysis for patas foods and tantalus foods, employing the above two variables, a discriminant function with positive coefficients for both variables was obtained. The mean discriminant-function score of patas foods was higher than that of tantalus foods. Despite being somewhat larger in weight, patas selectively fed on a smaller number of foods of higher quality than did tantalus. I discuss why the results are inconsistent with a well known body weight-diet relationship (Jarman-Bell principle). Energy-efficient locomotion enables patas to exploit not only small dispersed food items of high quality but also areas where high-quality foods are distributed in clumps.

Endometrial function in vervet monkeys (Cercopithecus aethiops): morphology, beta3 integrin and insulin-like growth factor binding protein-1 expression during the menstrual cycle and pregnancy in the normal and disrupted endometrium

The expression of endometrial beta3 integrin and insulin-like growth factor binding protein-1 (IGFBP-1) was studied in cycling and pregnant vervet monkeys. There were clear changes of beta3 integrin expression during the menstrual cycle, with the strongest immunostaining observed on day 26. Moderate to strong expression was observed during pregnancy. The expression of IGFBP-1 during the menstrual cycle was weak but upregulated during pregnancy with moderate to strong staining. The administration of a single dose of onapristone at 10 mg/kg on days 17, 21 and 22 of the menstrual cycle, followed by a biopsy on days 22, 22 and 26, respectively, and during pregnancy (34-44 days menstrual age) 24 h before the biopsy, disrupted and desynchronized the endometrium. However, no effect on beta3 integrin expression could be observed and staining reflected the untreated patterns. The same applied to IGFBP-1 except that during pregnancy the expression of this protein was reduced or abolished. The results suggest that beta3 integrin is associated with endometrial receptivity in vervet monkeys and that IGFBP-1 plays an important role during pregnancy in this species. The administration of onapristone appeared to only influence IGFBP-1 expression. To our knowledge, this is the first time that these endometrial proteins have been investigated in vervet monkeys. This study should therefore contribute to improving our understanding of the reproductive function of this species.

Adaptive and phylogenetic influences on musculoskeletal design in cercopithecine primates

Broad allometric studies of the musculoskeletal system have frequently sought to explain how locomotor variables have been influenced by body mass. To examine animals that vary widely in body mass, these studies have included taxa that differ in their locomotor adaptations and phylogenetic relatedness. Because these sources of diversity could obscure the effects of body mass,this study was designed to test the effects of adaptive differences in limb proportions and phylogeny, as well as body mass, on locomotor kinematics and extensor muscle mechanical advantage. More specifically, two hypotheses were tested in a sample of closely related animals: (i) that, among animals with similar body mass, those with longer limb segments should adopt more extended limb postures to moderate the joint and midshaft bending moments that they experience, and (ii) that body mass will have similar influences on joint posture and joint moments in closely related and diverse mammalian samples. Three-dimensional kinematic and synchronous force-platform data were collected for six individual cercopithecine monkeys ranging in mass from 4kg to 24kg and at a range of walking speeds. Comparisons among three monkeys with similar body mass but different limb segment lengths reveal a significant effect of limb proportion on posture. That is, animals with longer limbs frequently use more extended limb postures and can have correspondingly lower joint moments. The scaling of locomotor variables across the entire sample of closely related monkeys was generally similar to published results for a diverse sample of mammals, with larger monkeys having more extended limb postures, lower joint moments and greater effective mechanical advantage (EMA) for their limb extensor musculature. Ankle EMA, however, did not increase with body mass in the primate sample, suggesting that clade-specific adaptive differences (e.g. the use of arboreal supports by primates) may constrain the effects of body mass.

Breeding of African green monkeys (Cercopithecus aethiops) under indoor individually-caged conditions

This paper reports the results of reproduction with 45 wild African green monkeys (Cercopithecus aethiops) (36 females and 9 males) during the nine years from 1981 to 1989 under indoor individually-caged conditions. In 206 cases of menstruation observed, menstrual discharge lasted for 2.5 +/- 1.2 days in cycles of 22-48 days, and the length of each menstrual cycle was 31.2 +/- 6.5 days. Females who had regular menstrual cycles were subjected to "one-to-one timed mating"; females and males were put together on a one-to-one basis daily only for a certain period of time on and after the day of ovulation. Females who had irregular menstrual cycles or had no menstruation were subjected to "every-other-day mating"; females and males were put together on a one-to-one basis every other day for at least 16 weeks. The pregnancy rate (No. of pregnant females/No. of mated females) by one-to-one timed mating was 48.9% (116/237); 2.0 mating trials were needed to obtain one case of pregnancy. On the other hand, the pregnancy rate (No. of pregnant females/No. of mating trials) by every-other-day mating was 96% (48/50). Females who delivered normally totaled 129. The mean gestation period was 165 days when males, weighing 343 g on average at birth, were delivered, and 166 days when females, weighing 318 g on average at birth, were delivered. The male and female newborns were nursed for 131 and 138 days, respectively, on average. Details are summarized in Table 3. This paper also reports 23 cases of abortion, 6 stillbirths, and 6 cases of Caesarean section, by which three live fetuses and three dead fetuses were obtained.

Distribution and morphology of nigral axons projecting to the thalamus in primates

This study presents an analysis of the distribution and organization pattern of axons originating from the substantia nigra pars reticulata and projecting to the thalamus in monkeys. Biotin dextran amine was iontophoretically injected into different parts of the substantia nigra pars reticulata of monkeys (African green monkeys and macaques). In whatever part of the substantia nigra the injection was made, numerous axonal endings were found to be distributed within different thalamic regions: the ventral anterior nucleus and mainly its magnocellular part, the most ventromedial part of the ventral lateral nucleus, and the mediodorsal and parafascicular nuclei. Moreover, the nigrothalamic projection appeared to be topographically organized. Ten anterogradely labeled axons were reconstructed from serial sections. The axons terminated in three to six terminal fields per axon located in a relatively small portion of only one thalamic region. These terminal fields were variable in size and comprised 4-43 very thin, varicose branches. They consisted either of different axonal branches of the same axon or of different axons and covered 10-31 thalamic cell bodies. These findings demonstrate that the overall morphological organization of individual nigral axons is complex and allows single axons to influence thalamic neurons via a combination of divergent, convergent, and amplification processes.

Effects of lesions to area V6A in monkeys

In order to assess the role played by area V6A in visuomotor control, two adult green monkeys ( Cercopithecus aethiops) were subjected to small, bilateral lesions in the anterior bank of the parieto-occipital sulcus. Before and after the lesions, monkeys were tested for naturally designed reaching, grasping and picking-up pieces of food from various positions on a plate and from a differently oriented narrow slit. All movements were recorded with closed circuit TV and analysed offline on a single-photogram basis for defective reaching and wrist orientation. V6A lesions provoked parietal weakness, reluctance to move, and specific deficits in reaching, wrist orientation and grasping. Recovery from the observed deficits was rapid, even after a second, contralateral lesion was given, creating a bilateral lesion. Thus, together with previous anatomical and electrophysiological data, these results directly support the hypothesis that area V6A is part of the network involved in the control of reaching movements and wrist orientation.

The finding of an inverse relationship between social dominance and feeding priority among pairs of unfamiliar adult male vervet monkeys (Cercopithecus aethiops sabaeus)

Dominance is often presumed to confer priority of access to resources. This study evaluated the relationship between two assessments of dominance: (1) social dominance, based on agonistic interactions and (2) feeding priority among pairs of unfamiliar adult vervet monkeys (Cercopithecus aethiops sabaeus) differing in scrotal colour, but matched for height, weight and testicular volume, during paired introduction experiments. Results of this investigation showed that neither size differences nor scrotal colour were predictive of feeding priority, and social dominance was inversely related to feeding priority. This finding demonstrates that different assessments of dominance can yield different outcomes even within the same primate taxon. I propose that male dominance rank may best predict access to resources when there is direct contest competition over a resource, which is not immediately exhaustible, whereas highly impulsive low ranking males may gain a competitive edge in scramble competitions for ephemeral and small resources.

Stereological evaluation of neurons and glia in the monkey dorsal lateral geniculate nucleus following an early cerebral hemispherectomy

The effects of an early, unilateral cerebral hemispherectomy on the cytoarchitecture of the dorsal lateral geniculate nucleus (dLGN) were quantitatively evaluated in the green monkey. The dLGN ipsilateral to the lesion showed a 73% reduction in size, more than 99% neuronal cell loss, 50% increase in glial cell density, but a 50% reduction in the total number of glial cells. The total number of neural and glial cells estimated for the dLGN contralateral to the ablation did not differ from control values. Despite evidence for substantial degeneration of the ipsilateral dLGN, cytochrome oxidase histochemistry revealed a small population of surviving cells that exhibited features of neuronal cells. More surviving cells were found in the parvocellular than in the magnocellular layers, and surviving parvocellular cells had the same size-frequency distribution as Nissl-stained neurons in an intact animal. These findings suggest that the intrinsic geniculate circuitry may be able to sustain the residual interneurons that can, in turn, contribute to maintaining retinal and brainstem afferents. The remaining neurons in the dLGN following hemispherectomy appear to be insufficient in number to be importantly implicated in the residual visual functions that have been reported in some hemispherectomized patients.

Preliminary lack of evidence for simian odour preferences of savanna populations of Anopheles gambiae and other malaria vectors

The behavioural response to several culicine and anopheline mosquitoes to the odour of alternative hosts (human vs monkey) arranged in a choice set-up using odour-baited entry traps (OBETs) was assessed in a field experiment in south-eastern Senegal. The experimental protocol followed procedures analogous to those adopted in olfactometer laboratory tests. Two adult Cercopithecus aethiops and a child of similar mass slept inside separate tents and their odours were drawn to each one of two paired OBETs so that approaching mosquitoes could experience both odour-laden streams before "choosing" to fly against one of the two air currents and into the trap. The traps were set up in a riverine forest clearing near the town of Kedougou, where primates (Papio papio, Cercopithecus aethiops, and Erythrocebus patas) are common. A total of 192 mosquitoes belonging to 4 genera was captured during 8 trap nights. All major human malaria vectors including Anopheles gambiae sensu lato, An. funestus, and An. nili, which constituted the bulk of the trap catch (N = 153), clearly expressed a preference for human odour, with > 90% of captured mosquitoes caught in the human-baited trap. A sub-sample of specimens belonging to the An. gambiae complex caught in both traps was identified by rDNA-PCR and RFLP as An. gambiae sensu stricto molecular form S (7/10), and An. arabiensis (3/10). The only species that did not show a preference for the alternative odour-laden air streams, among those caught in significant numbers, were mosquitoes of the genus Mansonia, with both Ma. uniformis and Ma. africana weakly preferring human odour, but not at a statistically significant level. These results are in accordance with the hypothesis that the strongly anthropophilic feeding preferences of An. gambiae did not evolve from an ancestral association with non-human primates.

Morphology of renal afferent arterioles and glomeruli, heart weight, and blood pressure in primates

In a Caribbean outbred population of African green monkeys (Cercopithecus aethiops), 5 to 10% of feral adults have elevated blood pressure (BP). We have investigated whether the increased pressure is associated with abnormal renal afferent arteriole structure or glomerular number. In seven young adult (aged 7 to 13 years) male monkeys with consistently high BP (mean BP, 111 mm Hg; ketamine anesthesia) and seven controls (mean BP, 81 mm Hg), the morphology of the renal vasculature has been analyzed in three cortical zones. In each animal, the left kidney vasculature was fixed while relaxed and at known intravascular pressure, and afferent arteriolar diameter and media cross-sectional area were estimated. The right kidney was perfusion-fixed and prepared for unbiased stereologic estimation of glomerular number and size. No difference was found in afferent arteriole lumen diameter or media cross-sectional area, or in glomerular number or size, between the high BP group and controls. There was no difference in heart weight between the two groups, but there was a negative correlation between left ventricle heart weight and afferent arteriole diameter (controls: r = -0.81, P = .025; all animals: r = -0.70, P = .005, slope about 3.5% reduction in lumen diameter for 10% increase in heart weight). The results suggest that cardiac mass and renal afferent arteriole structure may be controlled by a common mechanism unrelated to BP measured in anesthesia. However, the lack of conscious measurements prevents conclusions as to whether this mechanism involves ambulatory BP.

Effect of dietary plant and animal protein intake on sperm quality in monkeys

This study was conducted to evaluate the influence of animal and plant protein diets on sperm quality indices over 120 days, using the vervet monkey (Cercopithecus aethiops), as a model. These experiments were divided into a 60-day period of high-protein consumption (+/-17% crude protein), followed by a 60-day term of sustainable protein intake (+/-9% crude protein). All the diets were designed to be similar, except for the source of dietary protein that the animals consumed. High-protein diets containing milk solids or maize + legumes had no significant effect on sperm quality parameters over the first 60 days. During the next 60 days of the investigation, sustainable plant and animal protein diets had differential effects on a number of sperm quality indices. When compared to the plant-based diet, the monkeys that were given the animal protein diet containing milk solids had lower sperm counts (p < .04), reduced sperm motility (p = .04), higher sperm midpiece abnormalities (p < .05), and a trend (p = .10) towards increased sperm head defects. These findings shed some light on the impact of variable dietary proteins on sperm quality, but should be followed by longer-term investigations around this important reproductive health issue.

The impact of dietary protein intake on serum biochemical and haematological profiles in vervet monkeys

This study evaluated the influence of Westernised and traditional African diets on biochemical and haematological profiles in vervet monkeys (Cercopithecus aethiops). Twelve adult male vervet monkeys bred at the Medical Research Council, all over 4 years of age and weighing more than 5 kg each, were divided into two groups of six individuals. These monkeys were raised on a standard in-house diet post-weaning, before they were fed for 8 weeks on diets containing milk solids (17.2%) or maize + legume (17.4%), as sources of high crude protein (+/- 3.5 g/kg). High protein diets had no significant effect on serum biochemical indices such as aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT) concentrations (P > 0.10). However, alanine aminotransferase (ALT) concentrations were significantly higher during week 8 (P < 0.05) for the maize + legume protein group. Alkaline phosphatase (ALP; P < 0.07), total protein (P < 0.0001), albumin (P < 0.02), and bilirubin (P < 0.003) were elevated in the milk solids group, while glucose levels were also significantly higher for the milk solids group (P < 0.05) between weeks 2 and 6. Elevated protein intake had no significant effect on haematological parameters such as red blood cells (RBC), platelet and white blood cell (WBC) counts, haemoglobin levels and monocyte and neutrophil concentrations (P > 0.10). In contrast, serum lymphocyte levels were significantly raised in the maize + legume protein group (P = 0.03), whereas values for the haematocrit (P < 0.002), mean cell volume (MCV; P < 0.03) and mean corpuscular haemoglobin concentration (MCHC; P < 0.0001) were higher in the monkeys that were fed the milk solids. This investigation showed that the type of dietary protein that is consumed may well affect certain biochemical and haematological indices in vervet monkeys. Compared to the group that were given the traditional African food regime, the animals on the Western-type milk solids diet showed significant elevations in a number of important biological indicators. However, longer-term studies should be completed in this area if we are to make firmer conclusions regarding the link between the nature of dietary proteins that are consumed and its effect on metabolism.

Formal method for objective assessment of primate color

To investigate primate color objectively, it is critical to employ tools that yield reliable measures of color samples. Primatologists have traditionally depended on color assessment methods that lack accuracy, precision, and replicability. In this work, we introduce the "red, green, and blue" (RGB) method, a technique combining digital video cameras and Adobe PhotoShop, as a means to assess and graphically represent primate color objectively. Here, we demonstrate the reliability and validity of the RGB method, and to outline the steps for assessing color samples, we report color measures obtained from the scrota of adult vervet monkeys.

A novel approach for herpes simplex virus type 1 amplicon vector production, using the Cre-loxP recombination system to remove helper virus

Helper-dependent HSV vectors (commonly known as HSV amplicons) are able to transfer genes into both dividing and quiescent cells, and thus have the potential to be widely used as vectors in physiological studies and gene therapy. Historically, these vectors were produced by superinfection with a helper virus that furnished all the trans-acting functions required for amplification and packaging of vector genomes into HSV-1 particles. In these systems, however, large amounts of potentially harmful helper virus are present in the vector stocks, thus restricting the use of these vectors. New helper virus-free packaging systems have been developed that utilize transfection of helper functions rather than infection and thus produce safer vector stocks. The vector titers as well as the amounts of particles obtained with these systems are, however, limited by the impossibility to reamplify the vector stocks. In this article, we present a novel system for producing large amounts of high-titer amplicon vector with low contamination by helper viruses. This system is based on the use of the Cre-loxP recombination system, which allows efficient deletion of the packaging signal of an HSV-1 recombinant helper virus (HSV-1-LaL) on Cre-expressing cells (TE-CRE30).

Foraging energetics in patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus): implications for reproductive seasonality

The patas monkeys (Erythrocebus patas) in Kala Maloue, Cameroon, have their birth season in the mid-dry season, whereas closely related, sympatric tantalus monkeys (Cercopithecus aethiops tantalus) have their birth season in the wet season. To evaluate the optimality of a species-specific birth season, I estimated the daily intake of available energy and gross protein, and energy expenditure for one individual of each sex of each species between respective birth and mating seasons. The monkeys obtained a larger amount of available energy and gross protein in the birth season than in the mating season. No significant seasonal differences in energy expenditure between the birth and mating season were found. Thus, the birth season appears to be timed to the season when the monkeys can obtain more surplus energy and protein. Interspecific differences in the optimality of birth season were attributed to widely exploitative foraging, supported by the patas' high locomotive ability, which may enable them to obtain more energy from seeds of Acacia seyal and gums of A. sieberiana, and more protein from grasshoppers and seeds of A. seyal in the mid-dry season than the tantalus monkeys. A review of preceding studies suggests that the availability of seeds of Acacia fruiting during the dry season may exert the dominant influence on timing of birth not only in patas but also in savanna monkeys (Cercopithecus aethiops), which include the tantalus monkeys.