A mobile cage facilitates periodic social contact and exercise for singly caged adult Vervet monkeys

Abstract: A mobile exercise cage that expands the quantity and improves the quality of the space available to singly caged adult Vervet monkey males is described. It was easily fitted into an existing caging system and the addition of a resident consort female made it possible for the males to mate and have regular social contact.     

Studies with human, baboon, and vervet monkey chorionic gonadotrophins

Vervet monkey, baboon, and human chorionic gonadotrophin(CG) were partially purified and their activity was monitored using radioimmuno- and radioreceptor-assays. They showed similar behaviour during ion exchange chromatography and isoelectric focusing and had isoelectric points between pH 4.50 and 5.13. The Stokes' radii were 32A, 34A, and 33A for vervet monkey, baboon, and human CG, respectively. Corresponding immunoassay potencies were 476.9, 1,143.1, and 9,600 IU/mg, while the bioassay estimates were 491.7, 997.8, and 8,950.0 IU/mg.     

THE NON-HUMAN PRIMATE ENDOCRINE PANCREAS: DEVELOPMENT,REGENERATION POTENTIAL AND METAPLASIA

An investigation into the development of the Vervet monkey endocrine pancreas revealed a sequence of occurrence of pancreatic peptides that differed from previous reports in mice, dog and human with PP and somatostatin occurring before glucagon and insulin. All four pancreatic peptides were identified, immunohistochemically, in only one of the pancreatic primordial buds, before fusion of the two buds to form the pancreas. This questions the hypothesis that the heterogeneous endocrine cell distribution seen in the adult pancreas is due to the contribution of only PP cells by the ventral bud and non-PP cells by the dorsal bud. Co-localization of glucagon and PP was observed extensively in the developing pancreas and the predominant expression of one over the other in an apparently organized non-random manner accounted for the glucagon- and PP-rich areas seen in the developing pancreas. A small number of cells immunoreactive to glucagon and PP were also observed in the adult. Reports of plasticity of differentiation of other pancreatic cells led us to investigate regeneration potential of the adult monkey pancreas. Partial obstruction of the Vervet monkey main pancreatic duct, by cellophane wrapping, resulted in duct cell proliferation and differentiation to form new endocrine tissue in a way that mimics normal organogenesis. Focal areas of hepatocytes were found in the regenerated pancreas of one monkey, illustrating further the latent developmental capabilities of adult pancreas cells. These findings could lead to interesting new therapies for pancreas and liver disease.     

Vasoactive intestinal polypeptide (VIP) as a putative neurotransmitter in penile erection

The localization of vasoactive intestinal polypeptide (VIP) in the male genitourinary tract was investigated in the rabbit and man by means of radioimmunoassay and immunohistochemistry. In addition, the in vitro effect of VIP upon penile smooth muscle from man, the Vervet monkey, and the rabbit was investigated. Significant concentrations of VIP immunoreactivity were found in the human penis and all the organs of the rabbit genital tract apart from the testis. VIP immunoreactive nerve fibres were observed in the erectile tissue of the human and rabbit penis and in the other organs of the rabbit genital tract apart from the testis. Fibres were most abundant in association with blood vessels, in smooth muscle tissue, and subepithelially in glandular tissue. Strips of smooth muscle taken from the corpus cavernosum of Vervet monkey and man showed a dose-dependent relaxation in response to VIP at concentrations of 6 X 10(-8) mol X L-1 and 6 X 10(-7) mol X L-1. The data indicate that VIP may be an inhibitory neurotransmitter involved in the nervous control of penile erection.     

Assessment of acrosomal integrity of vervet monkey spermatozoa after cryopreservation

Cryopreservation of Vervet monkey semen caused a highly significant reduction in the percentage of normal acrosomes and a highly significant increase in the percentage of mildly damaged, severely damaged, and lost acrosomes. This was demonstrated by staining ten post-thaw semen samples, which enabled a visualization of the acrosomal damage. The incidence of post-thaw intact acrosomes in this cryopreservation method was found to be similar to that reported for man and cynomolgus monkey semen.     

Fixation of vervet monkey oral mucosa for ultrastructural investigation--TEM

This study was undertaken to determine optimal fixation procedure for vervet monkey (Cercopithecus pygerythrus) oral mucosa. Perfusion and immersion fixation were investigated using glutaraldehyde and glutaraldehyde-paraformaldehyde fixatives with either a phosphate or sodium cacodylate buffer as vehicle and with osmolarities varying from 2010 to 320 mosm. Good fixation could not be obtained uniformly or consistently by perfusion. Vervet monkey oral mucosa is best fixed by first perfusing the head and neck of the animal with 250-500 ml 0.9% saline containing Procaine-HCl and heparin, followed by decapitation and immersion of the head in a 2.5% glutaraldehyde: 2% paraformaldehyde: 0.02 M sodium cacodylate buffered fixative (900 mosm) at 4 C for 24 hr.     

Fixation of Vervet Monkey Oral Mucosa for Ultrastructural Investigation–Tem

This study was undertaken to determine optimal fixation procedure for vervet monkey (Cercopithecui pygerythrta) oral mucosa. Perfusion and immersion fixation were investigated using glutaraldehyde and glutaraldehyde-paraformaldehyde fixatives with either a phosphate or sodium cacodylate buffer as vehicle and with osmolalities varying from 2010 to 320 mosm. Good fixation could not be obtained uniformly or consistently by perfusion. Vervet monkey oral mucosa is best fixed by first perfusing the head and neck of the animal with 250-500 ml 0.9% saline containing Procaine-HCl and heparin, followed by decapitation and immersion of the head in a 2.5% glutaraldehyde: 2% paraformaldehyde: 0.02 M sodium cacodylate buffered fixative (900 mosm) at 4 C for 24 hr.     

Observed Touch on a Non-Human Face Is Not Remapped onto the Human Observer's Own Face

Visual remapping of touch (VRT) is a phenomenon in which seeing a human face being touched enhances detection of tactile stimuli on the observer''s own face, especially when the observed face expresses fear. This study tested whether VRT would occur when seeing touch on monkey faces and whether it would be similarly modulated by facial expressions. Human participants detected near-threshold tactile stimulation on their own cheeks while watching fearful, happy, and neutral human or monkey faces being concurrently touched or merely approached by fingers. We predicted minimal VRT for neutral and happy monkey faces but greater VRT for fearful monkey faces. The results with human faces replicated previous findings, demonstrating stronger VRT for fearful expressions than for happy or neutral expressions. However, there was no VRT (i.e. no difference between accuracy in touch and no-touch trials) for any of the monkey faces, regardless of facial expression, suggesting that touch on a non-human face is not remapped onto the somatosensory system of the human observer.     

Fixation of Vervet Monkey Oral Mucosa for Ultrastructural Investigation-Tem

This study was undertaken to determine optimal fixation procedure for vervet monkey (Cercopithecui pygerythrta) oral mucosa. Perfusion and immersion fixation were investigated using glutaraldehyde and glutaraldehyde-paraformaldehyde fixatives with either a phosphate or sodium cacodylate buffer as vehicle and with osmolalities varying from 2010 to 320 mosm. Good fixation could not be obtained uniformly or consistently by perfusion. Vervet monkey oral mucosa is best fixed by first perfusing the head and neck of the animal with 250-500 ml 0.9% saline containing Procaine-HCl and heparin, followed by decapitation and immersion of the head in a 2.5% glutaraldehyde: 2% paraformaldehyde: 0.02 M sodium cacodylate buffered fixative (900 mosm) at 4 C for 24 hr.     

Cryopreservation of vervet monkey semen and recovery of progressively motile spermatozoa

A method to cryopreserve semen from the Vervet monkey (Cercopithecus aethiops) has been developed, yielding a mean post thaw recovery of 63.60% of pre-freeze progressive motility. The extender contained a TES-TRIS buffer, egg yolk, dextrose, streptomycin, penicillin, and glycerol as cryoprotectant. The pH ranged from 7.10–7.18 and the osmolality was 330–345 mOsmol/L.     

Organic acid concentrations and digesta movement in the gastrointestinal tract of the bushbaby (Galago crassicaudatus) and Vervet monkey (Cercopithecidae pygerythrus)

Studies were conducted to compare digestive functions in two species of sub-human primate, the bushbaby (Galago crassicaudatus) and the Vervet monkey (Cercopithecidae pygerythrus). Major differences were observed in the rate at which digesta markers moved through their respective gastrointestinal tracts, and in the concentration of lactic acid present in the gut. In both species, the caecum and colon were the principle sites of microbial activity and organic acid production.     

Using Parasitic Load to Measure the Effect of Anthropogenic Disturbance on Vervet Monkeys

Vervet monkeys, Chlorocebus pygerythrus, thrive in urban areas of KwaZulu-Natal, South Africa, and present a suitable model to assess parasitic load as a measure of anthropogenic disturbance, such as urbanization. We collected vervet monkey faecal samples from four study sites representing a gradient of land use and urbanization. We assessed faecal parasites using the faecal flotation method calculating eggs per gram and parasite richness. Overall, the more urban vervet monkey populations had a significantly higher parasite richness and abundance. Our study shows the applicability of using parasite load to measure the effect of urbanization on wildlife.     

Recognition of facial expressions in a Japanese monkey (Macaca fuscata) and humans (Homo sapiens)

Recognition of facial expressions by a Japanese monkey and two humans was studied. The monkey subject matched 20 photographs of monkey facial expressions and 20 photographs of human facial expressions. Humans sorted the same pictures. Matching accuracy by the monkey was about 80% correct for both human and monkey facial expressions. The confusion matrices of those facial expressions were analyzed by a multi-dimensional scaling procedure (MDSCAL). The resulting MDS plots suggested that the important cues in recognizing facial expressions of monkeys were “thrusting the mouth” and ‘raising the eyebrows.” Comparison of the MDS plots by the monkey subject with those by human subjects suggested that the monkey categorized the human “happiness” faces. This may suggest that the monkey has an ability to recognize human smile face even though it is learned. However, the monkey did not differentiate the human “anger/disgust” faces from the human “sad” faces, while human subjects clearly did. This may correlate with the lack of eyebrow movement in monkeys.     

Are faces of different species perceived categorically by human observers?

What are the species boundaries of face processing? Using a face-feature morphing algorithm, image series intermediate between human, monkey (macaque), and bovine faces were constructed. Forced-choice judgement of these images showed sharply bounded categories for upright face images of each species. These predicted the perceptual discrimination boundaries for upright monkey-cow and cow-human images, but not human-monkey images. Species categories were also well-judged for inverted face images, but these did not give sharpened discrimination (categorical perception) at the category boundaries. While categorical species judgements are made reliably, only the distinction between primate faces and cow faces appears to be categorically perceived, and only in upright faces. One inference is that humans may judge monkey faces in terms of human characteristics, albeit distinctive ones.     

Japanese macaques form a cross-modal representation of their own species in their first year of life

We tested whether infant Japanese macaques (Macaca fuscata) have a cross-modal representation of their own species. We presented monkeys with a photograph of either a monkey or a human face on an LCD monitor after playing back a vocalization of one of those two species. The subjects looked at the monitor longer when a human face was presented after the monkey vocalization than when the same face was presented after human vocalization. This suggests that monkeys recall and expect a monkey’s face upon hearing a monkey’s voice.     

Plasma and red blood cell total phospholipid fatty acid status of nonpregnant female Vervet monkeys (Cercopithecus aethiops) on a high carbohydrate maintenance diet

Nonhuman primates are of interest as models of human physiology to study the effect of multiple pregnancies on birth weight. Reference plasma and red blood cell (RBC) total phospholipids fatty acids were established in nonpregnant breeding female Vervet monkeys. Twenty-three clinically healthy nonpregnant Vervet monkeys (Cercopithecus aethiops), contained in a controlled closed environment and consuming a high carbohydrate diet (68 E%) that contained 20 E% fat and 12 E% protein were sampled for blood during a cross-sectional study. A low intake of ω3 fatty acids was reflected by a high ω6/ω3 ratio (66:1) of the diet. Inverse relations were seen between plasma and RBC total phospholipid fatty acids, 18:2ω6, 20:3ω6, and 20:4ω6, which suggested selective incorporation in membranes. Low levels of 20:5ω3 and 22:6ω3 of plasma and RBC total phospholipids render Vervet monkeys as ideal subjects to study the effect of ω3 fatty acid supplementation on pregnancy outcomes. Tichelaar HY, van Jaarsveld PJ, Smuts CM, Marais M, Mdhluli MC, Kruger M, Benadé AJS. Plasma and red blood cell total phospholipid fatty acid status of nonpregnant female Vervet monkeys (Cercopithecus aethiops) on a high carbohydrate maintenance diet. J Med Primatol 1998; 27:240–243. © Munksgaard, Copenhagen     

Cloning, expression, and pharmacological characterization of the GPR120 free fatty acid receptor from cynomolgus monkey: Comparison with human GPR120 splice variants

Activation of the GPCR GPR120 by free fatty acids has been reported to cause GLP-1 release in rodent intestine. One genetic sequence was reported for rodents, while two sequences were reported for human GPR120, BC101175 and NM_181745. A 1086 base pair sequence cloned from cynomolgus monkey colon cDNA has 85.1% and 83.4% homology with the mouse and rat GPR120 sequences, and 97.5% homology with the human BC101175 sequence. No splice variants of the cynomolgus monkey GPR120 receptor were found. Eight non-synonymous cSNPs were discovered with frequencies less than 4% in monkey samples tested. Real-time PCR demonstrated that, like the human, the highest GPR120 expression in cynomolgus monkey is in lung and colon. Studies measuring intracellular calcium release produced by free fatty acids and the small molecule GPR120 agonist GW9508 in cells expressing the cynomolgus monkey GPR120 receptor were compared to those expressing the human BC101175 splice variant. Long-chain free fatty acids produced the greatest response in cynomolgus monkey GPR120-expressing cells. GW9508 had similar efficacy at the cynomolgus monkey and at the BC101175 human GPR120 receptors. The cynomolgus monkey and the human GPR120 (BC101175) receptors have similar sequences and pharmacology. The possible significance of the alternate splice variant in human is discussed.     

Recognition of monkey faces by monkey experts

Human beings automatically discriminate human faces at the individual level. Infants aged 3 months implicitly recognise monkey faces, but this capacity disappears as recognition skills mature. Expertise is known to affect recognition capacities for different categories of stimuli that are not even face-like in their configuration. We have explored the capacity of adult experts and non-experts in primatology to recognise monkey faces in both explicit and implicit recognition tasks. In the explicit task, where subjects received the instruction to recognise a face seen previously, experts proved to be more accurate than non-experts. Experts were more affected by inversion than non-experts, suggesting that the processing of those faces is based on their configuration, as is generally observed for human faces. This replicates findings from Diamond and Carey (J Exp Psychol Gen 115:107–117, 1986) in dog experts. In the implicit recognition task, assessed by a visual paired comparison task where no instruction of recognition was given, automatic discrimination was observed for human faces but not for monkey faces. These results suggest that experience acquired by the time of adulthood did not lead the experts to develop recognition skills to the point of matching those exhibited for human faces.     

Relationships between the size and spatial morphology of human masseter and medial pterygoid muscles, the craniofacial skeleton, and jaw biomechanics

The relationship between human craniofacial morphology and the biomechanical efficiency of bite force generation in widely varying muscular and skeletal types is unknown. To address this problem, we selected 22 subjects with different facial morphologies and used magnetic resonance imaging, cephalometric radiography, and data from dental casts to reconstruct their craniofacial tissues in three dimensions. Conventional cephalometric analyses were carried out, and the cross-sectional sizes of the masseter and medial pterygoid muscles were measured from reconstituted sections. The potential abilities of the muscles to generate bite forces at the molar teeth and mandibular condyles were calculated according to static equilibrium theory using muscle, first molar, and condylar moment arms. On average, the masseter muscle was about 66% larger in cross section than the medial pterygoid and was inclined more anteriorly relative to the functional occlusal plane. There was a significant positive correlation (P less than 0.01) between the cross-sectional areas of the masseter and medial pterygoid muscles (r = 0.75) and between the bizygomatic arch width and masseter cross-sectional area (r = 0.56) and medial pterygoid cross-sectional area (r = 0.69). The masseter muscle was always a more efficient producer of vertically oriented bite force than the medial pterygoid. Putative bite force from the medial pterygoid muscle alone correlated positively with mandibular length and inversely with upper face height. When muscle and tooth moment arms were considered together, a system efficient at producing force on the first molar was statistically associated with a face having a large intergonial width, small intercondylar width, narrow dental arch, forward maxilla, and forward mandible. There was no significant correlation between muscle cross-sectional areas and their respective putative bite forces. This suggests that there is no simple relationship between the tension-generating capacity of the muscles and their mechanical efficiency as described by their spatial arrangement. The study shows that in a modern human population so many combinations of biomechanically relevant variables are possible that subjects cannot easily be placed into ideal or nonideal categories for producing molar force. Our findings also confirm the impression that similar bite-force efficiencies can be found in subjects with disparate facial features.     

A comparative study of facial growth in Homo and Macaca

Sections were prepared throughout all areas of the various facial bones in young, growing Rhesus monkeys. The detailed distribution of resorptive and depository surfaces and the distribution of endosteal and periosteal bone tissue types were determined. From this information, the sequence of remodeling changes associated with the growth of the facial skeleton was then interpreted. This study is a sequal to previous reports in which growth and remodeling processes in the human face were described using similar procedures. In the present report, growth changes in the monkey and human facial skeleton are compared and contrasted. The general plan of facial growth is similar in both species, but major differences exist in the area of the muzzle. The maxillary arch in the monkey is entirely depository in nature, and it grows in a forward and downward direction as the maxillary tuberosity simultaneously grows backward. In the human, the forward part of the maxillary arch is resorptive in character. This contrasting growth factor results in a downward but not forward movement of this area. The result is decreased prognathism. Other differences in growth pattern exist in the forehead, malar, chin, and orbit. The developmental and phylogenetic basis for the upright human face is discussed and evaluated.