Fetal and maternal factors associated with infant mortality in vervet monkeys

GLOBAL RETROSPECTIVE ANALYSIS OF PATHOLOGICAL FINDINGS IN ZOO-MANAGED GOELDI'S MONKEYS (CALLIMICO GOELDII), 1965-2018

As part of the collaborative efforts and goals of managing zoo-housed Goeldi's monkeys, or callimicos (Callimico goeldii), a retrospective review of gross and histopathological postmortem examination reports submitted to the International Studbook Coordinator was carried out by veterinary representatives of the Species Survival Plan to investigate disease trends. A total of 1,887 postmortem reports (1965-2018) collected from more than 150 institutions were reviewed. Histologic findings from 862 postmortem reports and primary causes of mortality were compiled to determine the most common findings. Within the study population, 419 individuals (48.6%) were male, 383 (44.4%) female, and the remaining 60 (7%) of undetermined sex. The primary lesion at death in adults was chronic renal disease. The other prevalent lesions included cardiac disease, myelolipomas, enteritis, colitis, and hepatitis. In Great Britain and mainland Europe, Yersinia spp. infection had significantly higher prevalence than in North American callimico populations. Multiple lesions affecting more than one organ system were identified in many animals of this study population. Results also showed that for adult callimicos in zoological institutions in North America, Europe, and Great Britain, life span has been increasing over the last 50 yr.

The early life microbiota mediates maternal effects on offspring growth in a nonhuman primate

Maternal parity can impact offspring growth, but the mechanisms driving this effect are unclear. Here, we test the hypothesis that vertically transmitted microbiota may be one potential mechanism. We analyzed 118 fecal and milk samples from mother-offspring vervet monkey dyads across the first 6 months of life. Despite poorer milk production, offspring born to low parity females grew larger than their counterparts. These offspring exhibited reduced alpha diversity in the first days of life, stronger seeding of maternal milk microbiota, Bacteroides fragilis dominance, and a greater abundance of glycan utilization pathways. Moreover, the attainment of greater body mass by 6 months of age was mediated by reduced early life alpha diversity and B. fragilis dominance. This work demonstrates that the establishment of a specialized, milk-oriented gut microbiota promotes infant growth and suggests an evolutionarily conserved developmental role of B. fragilis in primates.

Risk factors for neonatal brachial plexus palsy attributed to anatomy, physiology, and evolution

The inherent variable anatomy of the neonate and the uniquely-shaped maternal birth canal that is associated with the evolution of human bipedalism constitute risk factors for neonatal brachial plexus palsy (NBPP). For example, those neonates with a prefixed brachial plexus (BP) are at greater risk of trauma due to lateral neck traction during delivery than those with a normal or postfixed BP. Compared to adults, neonates also have extremely large and heavy heads (high head: body ratio) set upon necks with muscles and ligaments that are weak and poorly developed. Accordingly, insufficient cranial stability can place large torques on the cervical spinal nerves. In addition, the pelvic changes necessary for habitual bipedal posture resulted in a uniquely-shaped, obstruction-filled, sinusoidal birth canal, requiring the human fetus to complete a complicated series of rotations to successfully traverse it. Furthermore, although there are many risk factors that are known to contribute to NBPP, the specific anatomy and physiology of the neonate, except for macrosomia, is not considered to be one of them. In fact, currently, the amount of lateral traction applied to the neck during delivery is the overwhelming legal factor that is used to evaluate whether a birth attendant is liable in cases of permanent NBPP. Here, we suggest that the specific anatomy and physiology of the neonate and mother, which are clearly not within the control of the birth attendant, should also be considered when assessing liability in cases of NBPP.

Advanced maternal age impacts physiologic adaptations to pregnancy in vervet monkeys

The trend to delay pregnancy in the USA has resulted in the number of advanced maternal age (AMA) pregnancies to also increase. In humans, AMA is associated with a variety of pregnancy-related pathologies such as preeclampsia (PE). While AMA is known to be a factor which contributes to the development of pregnancy-induced diseases, the molecular and cellular mechanisms giving rise to this phenomenon are still very limited. This is due in part to lack of a preclinical model which has physiologic relevance to human pregnancy while also allowing control of environmental and genetic variability inherent in human studies. To determine potential physiologic relevance of the vervet/African green monkey (Chlorocebus aethiops sabaeus) as a preclinical model to study the effects of AMA on adaptations to pregnancy, thirteen age-diverse pregnant vervet monkeys (3-16 years old) were utilized to measure third trimester blood pressure (BP), complete blood count, iron measurements, and hormone levels. Significant associations were observed between third trimester diastolic BP and maternal age. Furthermore, the presence of leukocytosis with enhanced circulating neutrophils was observed in AMA mothers compared to younger mothers. Moreover, we observed a negative relationship between maternal age and estradiol, progesterone, and cortisol levels. Finally, offspring born to AMA mothers displayed a postnatal growth retardation phenotype. These studies demonstrate physiologic impairment in the adaptation to pregnancy in AMA vervet/African green monkeys. Our data indicate that the vervet/African green monkey may serve as a useful preclinical model and tool for deciphering pathological mediators of maternal disease in AMA pregnancy.

Transcriptomic Analysis of Cell-free Fetal RNA in the Amniotic Fluid of Vervet Monkeys (Chlorocebus sabaeus)

NHP are important translational models for understanding the genomic underpinnings of growth, development, fetal programming, and predisposition to disease, with potential for the development of early health biomarkers. Understanding how prenatal gene expression is linked to pre- and postnatal health and development requires methods for assessing the fetal transcriptome. Here we used RNAseq methodology to analyze the expression of cell-free fetal RNA in the amniotic fluid supernatant (AFS) of vervet monkeys. Despite the naturally high level of degradation of free-floating RNA, we detected more than 10,000 gene transcripts in vervet AFS. The most highly expressed genes were H19, IGF2, and TPT1, which are involved in embryonic growth and glycemic health. We noted global similarities in expression profiles between vervets and humans, with genes involved in embryonic growth and glycemic health among the genes most highly expressed in AFS. Our study demonstrates both the feasibility and usefulness of prenatal transcriptomic profiles, by using amniocentesis procedures to obtain AFS and cell-free fetal RNA from pregnant vervets.

MORTALITY IN COQUEREL'S SIFAKAS ( PROPITHECUS COQUERELI) UNDER HUMAN CARE: A RETROSPECTIVE SURVEY FROM THE DUKE LEMUR CENTER 1990-2015

  Coquerel's sifakas ( Propithecus coquereli) are diurnal, folivorous lemurs native to Madagascar and one of only two members of the genus Propithecus currently housed in human care settings outside of Madagascar. This species has a lifespan of approximately 30 yr but minimal information exists regarding morbidity and mortality in human care settings. In this retrospective study, medical records, postmortem exam, and autopsy reports from 56 animals housed at the Duke Lemur Center from 1990 to 2015 were evaluated. Mortality assessments included age, sex, time of year, histopathological findings, major organ system impacted, and etiological factors. Mortality was most prevalent among adults greater than 2 yr of age (42.9%) and neonates less than 7 days of age (30.4%). The top four morphological diagnoses accounted for 51.7% of all deaths and included stillbirths (19.6%), enteritis-colitis (12.5%), failure to thrive (10.7%), and systemic protozoal infections (8.9%). The two most commonly affected organ systems in animals over 7 days of age were multisystem disease (30.8%) and the gastrointestinal system (28.2%). Infections were the most common etiology with bacterial being the most prevalent followed by protozoal infections. The results provide insight into common causes of mortality of this species and can be used to guide management of this endangered primate and improve longevity in human care settings.

Microbial translocation into amniotic fluid of vervet monkeys is common and unrelated to adverse infant outcomes

Amniotic fluid was collected from pregnant female African green monkeys (n = 20). Analyses indicate microbial translocation into amniotic fluid during pregnancy is typical, and microbial load reduces across gestation. Microbial translocation does not relate to infant outcome or maternal factors. Lastly, we demonstrate that sample contamination is easily introduced and detectable.

Social and ecological factors influencing offspring survival in wild macaques

Premature loss of offspring decreases direct fitness of parents. In gregarious mammals, both ecological and social variables impact offspring survival and may interact with each other in this regard. Although a number of studies have investigated factors influencing offspring loss in mammals, we still know very little on how different factors interact with one another. We therefore investigated fetal and infant mortality in 3 large groups of wild crested macaques (Macaca nigra) over a period of up to 5 years by including potential social causes such as maternal dominance rank, male immigration, between group encounters, and ecological conditions such as rainfall in a multivariate survival analysis using Cox proportional hazards model. Infant but not fetal survival was most impaired after a recent takeover of the alpha-male position by an immigrant male. Furthermore, infant survival probability increased when there was an increase in number of group adult females and rainfall. Fetal survival probability also increased with an increase of these 2 factors, but more in high-ranking than low-ranking females. Fetal survival, unlike that of infants, was also improved by an increase of intergroup encounter rates. Our study thus stresses the importance of survival analyses using a multivariate approach and encompassing more than a single offspring stage to investigate the determinants of female direct fitness. We further provide evidence for fitness costs and benefits of group living, possibly deriving from high pressures of both within- and between-group competition, in a wild primate population.

Systems biology of the vervet monkey

Nonhuman primates (NHP) provide crucial biomedical model systems intermediate between rodents and humans. The vervet monkey (also called the African green monkey) is a widely used NHP model that has unique value for genetic and genomic investigations of traits relevant to human diseases. This article describes the phylogeny and population history of the vervet monkey and summarizes the use of both captive and wild vervet monkeys in biomedical research. It also discusses the effort of an international collaboration to develop the vervet monkey as the most comprehensively phenotypically and genomically characterized NHP, a process that will enable the scientific community to employ this model for systems biology investigations.

25(OH)D3 and cardiovascular risk factors in female nonhuman primates

OBJECTIVE

To determine if interindividual differences in plasma concentrations of 25-hydroxyvitamin D(3) (25(OH)D(3)) have pathophysiologic significance, we evaluated a cohort of female monkeys, seeking to identify associations with clinically relevant cardiovascular risk factors, including age, abdominal obesity (waist circumference), and high-density lipoprotein cholesterol (HDL-C).

METHODS

One hundred fifty-five female vervet monkeys (Chlorocebus aethiops sabaeus) aged 3-25 years consumed a typical western diet for 7-8 weeks that provided a woman's equivalent of approximately 1000 IU/day of vitamin D(3). Measurements of vitamin D(3) and HDL-C concentrations, as well as waist circumference, were obtained.

RESULTS

Among young monkeys (aged 3-5 years), compared to older monkeys (aged 16-25 years), the mean plasma 25(OH)D(3) concentrations were 82.3±3.2 ng/mL and 58.6±2.9 ng/mL (p<0.0001), respectively. Plasma 25(OH)D(3) concentrations had a range of 19.6-142.0 ng/mL (mean±standard error [SE] 66.4±1.7 ng/mL). 25(OH)D(3) concentrations were inversely associated with age (p<0.0001) and waist circumference (p=0.016) and were positively correlated with HDL-C (p=0.01). However, when statistically controlling for age, none of these relationships remained significant.

CONCLUSIONS

Higher plasma concentrations of 25(OH)D(3) were associated with more favorable cardiovascular risk factors, with inverse associations observed between 25(OH)D(3) and abdominal obesity, HDL-C, and age. These associations were no longer significant when controlling for age.