G-banding in the barbary macaque (Macaca sylvanus, Linnaeus, 1758) of Morocco

G-banding was performed on the lymphocytes of six barbary macaques (Macaca sylvanus). Four chromosomes appear to have polymorphic variants: number 1, number 4, number 16, and the “marker” chromosome, number 9. These polymorphic forms differe from the G-banding reported for Macaca mulatta, Macaca fascicularis, and Macaca arctoides. It may be that evolutionary relationships among various macaque species can be ascertained by using such chromosomal polymorphisms.     

Ancient genome‐wide admixture extends beyond the current hybrid zone between Macaca fascicularis and M. mulatta

Macaca fascicularis and Macaca mulatta are two of the most commonly used laboratory macaques, yet their genetic differences at a genome‐wide level remain unclear. We analysed the multilocus DNA sequence data of 54 autosomal loci obtained from M. fascicularis samples from three different geographic origins and M. mulatta samples of Burmese origin. M. fascicularis shows high nucleotide diversity, four to five times higher than humans, and a strong geographic population structure between Indonesian‐Malaysian and Philippine macaques. The pattern of divergence and polymorphism between M. fascicularis and M. mulatta shows a footprint of genetic exchange not only within their current hybrid zone but also across a wider range for more than 1 million years. However, genetic admixture may not be a random event in the genome. Whereas randomly selected genic and intergenic regions have the same evolutionary dynamics between the species, some cytochrome oxidase P450 (CYP) genes (major chemical metabolizing genes and potential target genes for local adaptation) have a significantly larger species divergence than other genes. By surveying CYP3A5 gene sequences of more than a hundred macaques, we identified three nonsynonymous single nucleotide polymorphisms that were highly differentiated between the macaques. The mosaic pattern of species divergence in the genomes may be a consequence of genetic differentiation under ecological adaptation and may be a salient feature in the genomes of nascent species under parapatry.     

Male reproductive timing in Rhesus macaques is influenced by the 5HTTLPR promoter polymorphism of the serotonin transporter gene

The 5HTTLPR polymorphism in the promoter region of the human serotonin transporter (SLC6A4) gene is known to be associated with various stress-related psychological and psychiatric phenomena. We observed that a similar diallelic polymorphism in the orthologous gene of rhesus macaques (Macaca mulatta) was related to the reproductive life history of 580 males residing in the free-ranging colony of Cayo Santiago, Puerto Rico, between 1985 and 1998. At first glance, the polymorphism appeared to be selectively neutral because no difference in total reproductive output was noted between males of different 5HTTLPR genotypes. However, whereas heterozygotes were significantly more reproductive than homozygotes at intermediate age (10-13 yr), the opposite held true before and after this period (n = 682 offspring; randomization P = 0.014). This association, which explains approximately 7% of the observed variation in sire age, most likely reflects different natal dispersal patterns and represents the first reported instance of a genetic influence on reproductive timing in mammals.     

An international multicenter association study of the serotonin transporter gene in persistent ADHD

Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder affecting children and adults. It has been suggested that gene variants related to serotonin neurotransmission are associated with ADHD. We tested the functional promoter polymorphism 5‐HTTLPR and seven single nucleotide polymorphisms in SLC6A4 for association with ADHD in 448 adult ADHD patients and 580 controls from Norway. Replication attempts were performed in a sample of 1454 Caucasian adult ADHD patients and 1302 controls from Germany, Spain, the Netherlands and USA, and a meta‐analysis was performed also including a previously published adult ADHD study. We found an association between ADHD and rs140700 [odds ratio (OR ) = 0.67; P = 0.01] and the short (S) allele of the 5‐HTTLPR (OR = 1.19; P = 0.06) in the Norwegian sample. Analysis of a possible gender effect suggested that the association might be restricted to females (rs140700: OR = 0.45; P = 0.00084). However, the meta‐analysis of 1894 cases and 1878 controls could not confirm the association for rs140700 [OR = 0.85, 95% confidence interval (CI) = 0.67–1.09; P = 0.20]. For 5‐HTTLPR, five of six samples showed a slight overrepresentation of the S allele in patients, but meta‐analysis refuted a strong effect (OR = 1.10, 95% CI = 1.00–1.21; P = 0.06). Neither marker showed any evidence of differential effects for ADHD subtype, gender or symptoms of depression/anxiety. In conclusion, our results do not support a major role for SLC6A4 common variants in persistent ADHD, although a modest effect of the 5‐HTTLPR and a role for rare variants cannot be excluded.     

Genetic variation and evolution in the red cell carbonic anhydrase isozymes of macaque monkeys

The electrophoretic phenotypes of the two isozymes of red cell carbonic anhydrase, CA I and CA II, are described in nine species of macaque monkeys from southeast Asia and Japan. Twelve phenotypes of CA I, apparently under the control of seven alleles, and five phenotypes of CA II, under the control of three alleles, were found in the different macaque populations studied. Extensive electrophoretic polymorphisms of CA I were found in three species (Macaca nemestrina, Macaca speciosa, and Macaca fuscata), and polymorphisms at the CA II locus were found in Macaca irus, Macaca mulatta, and M. nemestrina. In addition to the electrophoretic polymorphisms at the CA I locus in M. nemestrina, an inherited deficiency of CA I was also discovered in which approximately 30% of the individuals in all populations of M. nemestrina tested showed the deficient phenotype. Although the recessive gene controlling this deficiency appears to be an allele of the CA I locus, it is postulated that the CA I deficiency could also be under the control of a closely linked gene. The comparative data on the extent of genetic variation observed in the two isozymes of red cell carbonic anhydrase in macaques appear to support the concept that CA I has evolved more rapidly than CA II in mammals.Supported by USPHS grant GM-15419 and NSF grants GF-253, GB-7426, and GB-15060 of the U.S.-Japan Cooperative Science and Systemic Biology Programs.     

Maternal childhood adversity and child temperament: An association moderated by child 5‐HTTLPR genotype

We examined transgenerational effects of maternal childhood adversity on child temperament and a functional promoter polymorphism, 5‐HTTLPR, in the serotonin‐transporter gene (SLC6A4) as potential moderators of such maternal influences in 154 mother–child dyads, recruited into a longitudinal birth cohort study. We examined the interactive effects of maternal childhood experience using an integrated measure derived from Childhood Trauma Questionnaire (CTQ) and Parental Bonding Index (PBI). Triallelic genotyping of 5‐HTTLPR was performed. A measure of ‘negative emotionality/behavioural dysregulation’ was derived from the Early Childhood Behaviour Questionnaire at 18 and 36 months. Negative emotionality/behavioural dysregulation was highly stable between 18 and 36 months and predicted psychosocial problems at 60 months. After controlling multiple demographics as well as both previous and concurrent maternal depression there was a significant interaction effect of maternal childhood adversity and offspring 5‐HTTLPR genotype on child negative emotionality/behavioural dysregulation (β = 1.03, t_11,115 = 2.71, P < .01). The results suggest a transgenerational effect of maternal developmental history on emotional function in the offspring, describing a pathway that likely contributes to the familial transmission of vulnerability for psychopathology.     

Contribution of the functional 5-HTTLPR variant of the SLC6A4 gene to obesity risk in male adults

Background: A polymorphism in the promoter region of the serotonin transporter (5‐HTTLPR) gene SLC6A4 shows functionally important 44‐bp insertion/deletion alleles: long (L) and short (S). We have previously found that the S allele is a genetic risk factor for obesity in adolescents. Objective: The aim of this study was to evaluate whether the S/L variant of the SLC6A4 gene is associated with BMI as a continuous trait and also with obesity in a large sample of adult men of European ancestry included in a cross‐sectional, population‐based study. Methods and Procedures: The study group was composed of individuals who were randomly recruited from a factory in the Buenos Aires metropolitan area and who underwent an annual health examination. Results: We observed that among 1,329 unrelated subjects, aged 34.6 ± 0.3 years, age‐adjusted BMI values (expressed as mean ± s.e.) for each genotype showed statistically significant differences across genotypic groups (LL: 25.4 ± 0.2, LS: 26.0 ± 0.1 and SS: 26.7 ± 0.2, P < 0.0002). In addition, association tests showed that the 5‐HTTLPR‐genotype distribution was significantly different between 692 lean (BMI ≤ 25 kg/m2) and 637 obese (BMI ≥ 27 kg/m2) individuals. We found a 1.36 odds ratio (OR) (95% CI 1.01–1.85) for obesity in SS carriers in comparison with LL carriers, P = 0.026. Discussion: In conclusion, our findings indicate that 5‐HTTLPR polymorphism may be linked with BMI and also with obesity and/or overweight in adult male population, reinforcing the role of the serotonin transporter as a risk factor for the obesity phenotype and suggesting potential new avenues for its pharmacological treatment.     

The reproductive history of a hybrid female (Macaca mulatta ×Macaca fuscata)

In 1968 a female hybrid (Macaca mulatta ×Macaca fuscata) was born into the freeranging Arashiyama B troop of Japanese macaques (Macaca fuscata). At the age of 4 years this hybrid had her first offspring and by 1978 had accumulated eight descendants (five daughters, one son and two grandchildren). In this report the reproductive history of the hybrid is discussed and compared to the other non-hybrid members of the troop.     

The evolution of “egalitarian” and “despotic” social systems among macaques

Recent studies of captive macaques have revealed considerable inter-species differences in dominance styles among females. In “egalitarian” species such as stumptail (Macaca arctoides) or tonkean macaques (M. tonkeana), social interactions are more symmetrical and less kin-biased than in “despotic” species such as Japanese (M. fuscata) or rhesus macaques (M. mulatta). Field observations of moor macaques (M. maurus), close relatives of tonkean macaques, suggest that tolerance during feeding characterizes their egalitarian dominance style in the natural habitat. Although it has been proposed that communal defense against other groups may be the main selective force in the evolution of egalitarian dominance style among females, few field data support this prediction. A game theory analysis showed that both an “egalitarian” strategy and a “despotic” strategy are possible evolutionarily stable strategies (ESS) under certain conditions. The difference in dominance styles might reflect the difference in ESS. This means that an egalitarian dominance style can emerge without strong between-group contest competition. A phylogenetic comparison among macaques suggests that despotic dominance styles very likely evolved from egalitarian dominance styles. In the future, primate socioecological studies should pay more attention to the evolutionary history of each species.     

Evidence for epistasis between <Emphasis Type="Italic">SLC6A4</Emphasis> and <Emphasis Type="Italic">ITGB3</Emphasis> in autism etiology and in the determination of platelet serotonin levels

Autism is a neurodevelopmental disorder of unclear etiology. The consistent finding of platelet hyperserotonemia in a proportion of patients and its heritability within affected families suggest that genes involved in the serotonin system play a role in this disorder. The role in autism etiology of seven candidate genes in the serotonin metabolic and neurotransmission pathways and mapping to autism linkage regions (SLC6A4, HTR1A, HTR1D, HTR2A, HTR5A, TPH1 and ITGB3) was analyzed in a sample of 186 nuclear families. The impact of interactions among these genes in autism was assessed using the multifactor-dimensionality reduction (MDR) method in 186 patients and 181 controls. We further evaluated whether the effect of specific gene variants or gene interactions associated with autism etiology might be mediated by their influence on serotonin levels, using the quantitative transmission disequilibrium test (QTDT) and the restricted partition method (RPM), in a sample of 109 autistic children. We report a significant main effect of the HTR5A gene in autism (P = 0.0088), and a significant three-locus model comprising a synergistic interaction between the ITGB3 and SLC6A4 genes with an additive effect of HTR5A (P < 0.0010). In addition to the previously reported contribution of SLC6A4, we found significant associations of ITGB3 haplotypes with serotonin level distribution (P = 0.0163). The most significant models contributing to serotonin distribution were found for interactions between TPH1 rs4537731 and SLC6A4 haplotypes (P = 0.002) and between HTR1D rs6300 and SLC6A4 haplotypes (P = 0.013). In addition to the significant independent effects, evidence for interaction between SLC6A4 and ITGB3 markers was also found. The overall results implicate SLC6A4 and ITGB3 gene interactions in autism etiology and in serotonin level determination, providing evidence for a common underlying genetic mechanism and a molecular explanation for the association of platelet hyperserotonemia with autism. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cognition in aged rhesus monkeys: effect of DHEA and correlation with steroidogenic gene expression

Estradiol supplementation has been shown to enhance cognitive performance in old ovariectomized rhesus macaques (Macaca mulatta). To determine if similar benefits could be achieved in perimenopausal animals using alternative hormonal supplements, we administered dehydroepiandrosterone (DHEA) to old ovary‐intact female rhesus macaques for ～2.5 months. Using computerized touch screen memory tasks, including delayed response (DR) and delayed matching‐to‐sample (DMS), we observed improved performance with time in all of the animals but failed to detect a significant effect of DHEA. On the other hand, gene expression profiling disclosed a significant correlation between cognitive performance and the expression of several steroidogenic and steroid‐responsive genes. The DR performance was positively correlated with hippocampal expression of AKR1C3 and STAR and negatively correlated with the expression of SDRD5A1. A positive correlation was also found between DMS performance and prefrontal cortical expression of AKR1C3 and a negative correlation with STAR, as well as a negative correlation with the hippocampal expression of HSD11B1 and NR3C1. Taken together, the results suggest that steroidogenic gene regulation within the brain may help to maintain cognitive function during the perimenopausal transition period, despite a decline in sex‐steroid levels in the circulation.     

Epigenetic Regulation of Serotonin Transporter in Psychiatric Disorders

SLC6A4 (solute carrier family 6,member 4) gene encodes a serotonin transporter (5-hydroxytryptamine transporter,HTT),which transports synaptic serotonin into presynaptic terminal.SLC6A4 is known to be the target of antidepressants such as selective serotonin reuptake inhibitors (SSRIs).Inhibition of HTT increases synaptic serotonin concentration and thereby exerts antidepressant efficacy.A large number of genetic studies suggest the contribution of genetic variations of SLC6A4 to various psychiatric disorders.The most studied genetic variation,HTT-linked polymorphic region (HTTLPR),is located at the promoter region of SLC6A4.     

Y-Chromosome and Mitochondrial Markers in Macaca fascicularis Indicate Introgression with Indochinese M. mulatta and a Biogeographic Barrier in the Isthmus of Kra

This is the first report of Y-chromosome introgression between primate species. We sequenced 3.1 Kb of Y-chromosome DNA and 1.5 Kb of mtDNA for 27 macaques of Fooden's (Folia Primatol. [1976] 25: 225–236) fascicularis species group and 5 outgroup taxa (Macaca sylvanus, Papio hamadryas, Theropithecus gelada, Allenopithecus nigroviridis, and Cercopithecus mona). Phylogenies constructed separately for the paternal and maternal data sets show a Y-chromosome paraphyly among lineages of Macacafascicularis, but a mitochondrial monophyly for the same individuals. The Y-chromosome topology depicts Indochinese Macaca fascicularis haplotypes joining with those of M. mulatta, followed by M. cyclopis and M. fuscata, before clustering with a clade of lineages of M. fascicularis from peninsular Malaysia, Indonesia, and the Philippines. These contrasting patterns of mitochondrial and Y-chromosome DNA, evaluated in the context of the evolutionary consequences of macaque sex-biased dispersal, present strong evidence for contemporary hybridization between Macaca fascicularis and M. mulatta in Indochina and a biogeographic barrier in the Isthmus of Kra.     

Positive selection of Toll-like receptor 2 polymorphisms in two closely related old world monkey species, rhesus and Japanese macaques

Toll-like receptor 2 (TLR2) plays an important role in the recognition of a variety of pathogenic microbes. In the present study, we compared polymorphisms of TLR2 locus in two closely related old world monkey species, rhesus monkey (Macaca mulatta) and Japanese monkey (Macaca fuscata). By nucleotide sequencing of the third exon of TLR2 gene from 21 to 35 respective individuals, we could assign 17 haplotype combinations of 17 coding SNPs of ten non-synonymous and seven synonymous substitutions. A non-synonymous substitution at codon position 326 appeared to be differentially fixed in each species, asparagine for M. mulatta whereas tyrosine for M. fuscata, and may contribute to certain functional properties because it locates in the region contributing to ligand binding and interaction with dimerization partner of TLR2-TLR1 heterodimeric complex. Although TLR2 alleles have diverged to similar extent in both species, they have evolved in significantly different ways; TLR2 of M. fuscata has undergone purifying selection while the membrane-proximal part of the extracellular domain of M. mulatta TLR2 exhibits higher rates of non-synonymous substitutions, indicating a trace of Darwinian positive selection.     

Phylogenetic Relationships of the Macaques (Cercopithecidae: Macaca), Inferred from Mitochondrial DNA Sequences

To study the phylogenetic relationships of the macaques, five gene fragments were sequenced from 40 individuals of eight species: Macaca mulatta, M. cyclopis, M. fascicularis, M. arctoides, M. assamensis, M. thibetana, M. silenus, and M. leonina. In addition, sequences of M. sylvanus were obtained from Genbank. A baboon was used as the outgroup. The phylogenetic trees were constructed using maximum-parsimony and Bayesian methods. Because five gene fragments were from the mitochondrial genome and were inherited as a single entity without recombination, we combined the five genes into a single analysis. The parsimony bootstrap proportions we obtained were higher than those from earlier studies based on the combined mtDNA dataset. Excluding M. arctoides, our results are generally consistent with the classification of Delson (1980). Our phylogenetic analyses agree with earlier studies suggesting that the mitochondrial lineages of M. arctoides share a close evolutionary relationship with the mitochondrial lineages of the fascicularis group of macaques (and M. fascicularis, specifically). M. mulatta (with respect to M. cyclopis), M. assamensis assamensis (with respect to M. thibetana), and M. leonina (with respect to M. silenus) are paraphyletic based on our analysis of mitochondrial genes.     

The combined effects of the 5‐ HTTLPR and HTR1A rs6295 polymorphisms modulate decision making in schizophrenia patients

Decision making ability has been reported to be impaired in schizophrenia patients, but no research has examined the genetic bases of this impairment. This study investigated how decision making was affected by the genetic variants in the serotonin transporter gene (triallelic 5‐ HTTLPR) and serotonin receptor 1A gene (rs6295) and their interaction in 465 schizophrenia patients and 448 healthy controls. The Iowa Gambling Task (IGT) was used to evaluate decision making under ambiguity (the first 40 trials) and decision making under risk (the last 60 trials). Results showed that, among the patients, the main effects of 5‐ HTTLPR (F_2,16 = 6.54, P = 0.002) and HTR1A rs6295 (F_2,16 = 3.87, P = 0.021) polymorphisms and their interaction effect (F_4,16 = 3.32, P = 0.005) were significant for the first 40 trials, with the GG genotype of HTR1A rs6295, the L′L′ genotype of 5‐ HTTLPR and the GG‐L′L′ combination showing poorer IGT performance than their counterparts. Results for the healthy controls showed a similar pattern but did not reach statistical significance. No significant effects were found for the last 60 trials. These results are discussed in terms of their implications for our understanding of the genetic mechanisms of decision making in schizophrenia patients as well as healthy adults.     

Fatal pulmonary acariasis in an aged indoor rhesus macaque (Macaca mulatta)

Pulmonary acariasis is a sporadic, incidental finding in colony‐raised rhesus macaques (Macaca mulatta). Prophylactic treatment in indoor‐raised and indoor‐housed macaques is not routine due to low prevalence, lack of clinical significance, and potential risk of toxicosis. This case is an unusually severe infestation of Pneumonyssus simicola in an indoor‐housed rhesus macaque, which ultimately resulted in this animal's death.     

Coat Color Variation and Pigmentation Gene Expression in Rhesus Macaques (Macaca mulatta)

Light-dark coat color variation is a common aspect of color diversity within and across mammalian taxa. This variation in pelage brightness is associated with aspects of evolutionary ecology, particularly for primates, but little is known about the genetic mechanisms underlying light-dark differences in pelage pigmentation. Previous work, focusing particularly on macaques (Genus Macaca), has found no clear relationship between color variation and coding sequences of key pigmentation genes. This suggests that other loci and/or gene regulatory differences underlie this variation and raises the question of how patterns of gene expression differ in light verses dark hair follicles. Here, we examine relative expression levels of pigmentation genes in hair follicles from free-ranging rhesus macaques (Macaca mulatta) showing stark light-dark coat color variation. We quantified the brightness (reflectance) of plucked hair tufts using a spectrophotometer. We extracted RNA from the follicles and used quantitative RT-PCR to measure the relative amounts of gene product (mRNA) for seven candidate pigmentation genes (MITF, MC1R, MGRN1, ATRN, SLC24A5, TYRP1, and DCT). Expression values were normalized with the house-keeping gene ACTB. All candidate genes were expressed at similar levels in dark, intermediate, and light hair, and thus, light-dark variation in macaque coat color is unlikely to be due to differences in the expression of these key pigmentation genes. This study represents the first examination of gene expression and natural color variation in a non-human primate population. Our results indicate that even in a system, like pigmentation, where a candidate-gene approach is promising, identifying important intra-specific gene regulatory differences remains challenging.     

Genetic load is associated with hypothalamic–pituitary–adrenal axis dysregulation in macaques

Dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis pathway is associated with several neuropsychiatric disorders, including post‐traumatic stress disorder (PTSD), major depressive disorder (MDD), schizophrenia and alcohol abuse. Studies have demonstrated an association between HPA axis dysfunction and gene variants within the cortisol, serotonin and opioid signaling pathways. We characterized polymorphisms in genes linked to these three neurotransmitter pathways and tested their potential interactions with HPA axis activity, as measured by dexamethasone (DEX) suppression response. We determined the percent DEX suppression of adrenocorticotropic hormone (ACTH) and cortisol in 62 unrelated, male rhesus macaques. While DEX suppression of cortisol was robust amongst 87% of the subjects, ACTH suppression levels were broadly distributed from ?21% to 66%. Thirty‐seven monkeys from the high and low ends of the ACTH suppression distribution (18 ‘high’ and 19 ‘low’ animals) were genotyped at selected polymorphisms in five unlinked genes (rhCRH, rhTPH2, rhMAOA, rhSLC6A4 and rhOPRM). Associations were identified between three variants (rhCRH‐2610C>T, rhTPH2 2051A>C and rh5‐HTTLPR) and level of DEX suppression of ACTH. In addition, a significant additive effect of the ‘risk’ genotypes from these three loci was detected, with an increasing number of ‘risk’ genotypes associated with a blunted ACTH response (P = 0.0009). These findings suggest that assessment of multiple risk alleles in serotonin and cortisol signaling pathway genes may better predict risk for HPA axis dysregulation and associated psychiatric disorders than the evaluation of single gene variants alone.