Wild Bornean orangutans experience muscle catabolism during episodes of fruit scarcity.

Pronounced temporal and spatial variation in the availability of food resources can produce energetic deficits in organisms. Fruit-dependent Bornean orangutans face extreme variation in fruit availability and experience negative energy and protein balance during episodes of fruit scarcity. We evaluate the possibility that orangutans of different sexes and ages catabolize muscle tissue when the availability of fruit is low. We assess variation in muscle mass by examining the relationship between urinary creatinine and specific gravity and use the residuals as a non-invasive measure of estimated lean body mass (ELBM). Despite orangutans having a suite of adaptations to buffer them from fruit scarcity and associated caloric deficits, ELBM was lower during low fruit periods in all age-sex classes. As predicted, adult male orangutans had higher ELBM than adult females and immatures. Contrary to expectation, flanged and unflanged males did not differ significantly in ELBM. These findings highlight the precarity of orangutan health in the face of rapid environmental change and add to a growing body of evidence that orangutans are characterized by unique metabolic traits shaped by their unpredictable forest environment.

Cloning, purification and characterization of non-human primate 12/15-lipoxygenases.

The enzyme 15-lipoxygenase-1 (15-LO-1) possesses mainly 15-LO activity and has so far only been described in human cells and rabbit reticulocytes. The animal ortholog, except rabbit reticulocytes, is an enzyme with predominantly a 12-lipoxygenase activity, commonly referred to as 12/15-LO. We describe herein the characterization of the 12/15-LOs in Macaca mulatta (rhesus monkey) and in Pongo pygmaeus (orang-utan). The rhesus and the orang-utan enzymes have mainly 12-lipoxygenase and 15-lipoxygenase activity, respectively, and they display 94% and 98% identity to the human 15-LO-1 protein. The rhesus enzyme was functionally different from the human enzyme with respect to substrate utilization in that anandamide was used differently and that the rhesus enzymes positional specificity could be affected by the substrate concentration. Furthermore, genomic data indicate that chimpanzees express an enzyme with mainly 15-lipoxygenase activity whereas marmosets express an enzyme with mainly 12-LO activity. Taken together, the switch during evolution from a 12-lipoxygenating enzyme in lower primates to a 15-lipoxygenating enzyme in higher primates and man might be of importance for the biological function of this enzyme.

Potential applications of urinary C-peptide of insulin for comparative energetics research.

The study of comparative energetics offers a valuable way to identify broad ecological principles and assess the functional significance of energetic adaptations during the course of evolution. Yet, the quantification of energetic status for nonhuman primates under natural conditions remains one of the most challenging aspects of comparative energetics research. Here, we report on the development of a noninvasive field method for measuring energetic status in great apes, humans, and possibly other nonhuman primates. Specifically, we have explored measurement of a urinary metabolite of insulin (C-peptide) as a physiological marker of energetic condition in chimpanzees and orangutans. We performed three validation studies and successfully measured C-peptide in urine samples from captive chimpanzees, wild chimpanzees, and wild orangutans. Urinary C-peptide measures gave indications of being a reliable signal of energetic status in both species. For chimpanzees and orangutans in the wild, baseline urinary C-peptide levels were higher during periods of fruit abundance than periods of low fruit availability. Urinary C-peptide levels were also higher for well-fed captive chimpanzees compared with wild chimpanzees. Although sample size was small, top-ranking male chimpanzees showed higher C-peptide levels in the wild than low-ranking males only during the period of fruit abundance. These preliminary results indicate that further development of the urinary C-peptide method could expand opportunities to quantify energetic condition for great apes in the wild and generate new data for comparative research. We highlight specific applications for studying great ape reproduction as well as the nutritional ecology of human foragers.

Sub-array normalization subject to differentiation.

From microarray measurement, we seek differentiation of mRNA expressions among different biological samples. However, each array has a 'block effect' due to uncontrolled variation. The statistical treatment of reducing the block effect is usually referred to as normalization. Our perspective is to find a transformation that matches the distributions of hybridization levels of those probes corresponding to undifferentiated genes between arrays. We address two important issues. First, array-specific spatial patterns exist due to uneven hybridization and measurement process. Second, in some cases a substantially large portion of genes are differentially expressed between a target and a reference array. For the purpose of normalization we need to identify a subset that exclude those probes corresponding to differentially expressed genes and abnormal probes due to experimental variation. Least trimmed squares (LTS) is a natural choice to achieve this goal. Substantial differentiation is protected in LTS by setting an appropriate trimming fraction. To take into account any spatial pattern of hybridization, we divide each array into sub-arrays and normalize probe intensities within each sub-array. We illustrate the problem and solution through an Affymetrix spike-in dataset with defined perturbation and a dataset of primate brain expression.

A human-specific gene in microglia.

Recent studies have shown multiple differences between humans and apes in sialic acid (Sia) biology, including Siglecs (Sia-recognizing-Ig-superfamily lectins). Comparisons with the chimpanzee genome indicate that human SIGLEC11 emerged through human-specific gene conversion by an adjacent pseudogene. Conversion involved 5 cent untranslated sequences and the Sia-recognition domain. This human protein shows reduced binding relative to the ancestral form but recognizes oligosialic acids, which are enriched in the brain. SIGLEC11 is expressed in human but not in chimpanzee brain microglia. Further studies will determine if this event was related to the evolution of Homo.

Fiber digestibility by the orangutan (Pongo abelii): in vitro and in vivo.

Limited nutritional information exists on diets of free-ranging orangutans, Pongo abelii and P. pygmaeus. Although they are classified as frugivores, the chemical composition of their diet and their gastrointestinal anatomy suggest that they rely on fiber fermentation for a substantial portion of energy. However, the extent to which they can ferment fiber is not known. Continuous culture systems, inoculated with orangutan fecal bacteria, were established to determine the fiber-digesting capacity of orangutan hindgut microflora. The cultures received one of four treatments: soybean hulls, ground corncobs, corn starch, or no food. Neither dry matter nor neutral detergent fiber digestibilities differed significantly among treatments. However, neutral detergent fiber digestibilities were high for both the soybean hull (88.4%) and ground corncob (86.1%) treatments, indicating that the microflora had a strong fibrolytic capability. To determine whether the same fiber-degrading capacity occurred in vivo, two adult orangutans and one juvenile were fed four gel-matrix diets containing soybean hulls, ground corncobs, or ground primate biscuits. Neutral detergent fiber concentrations (dry matter basis) of the gel matrices were 52.9% with soybean hulls, 46.8% and 63.7% with ground corncobs, and 31.3% with ground primate biscuits. A fifth diet consisted of primate biscuits with 27.3% neutral detergent fiber (dry matter basis) and was considered the baseline diet. Neutral detergent fiber digestibility (74.5%) was greatest (P < 0.05) for the soybean hull gel diet and least (57.5% and 45.0%, respectively; P < 0.05) for the 63.7% neutral detergent fiber (dry matter basis) corncob gel diet and the baseline primate biscuit diet. Total volatile fatty acid concentrations in orangutan feces were not significantly different among diets; however, molar proportions of acetic, propionic, and butyric acid differed (P < 0.05) among diets. The results from both studies indicated that orangutans are capable of extensive fiber fermentation.

Neuropeptide Y in the infundibular nucleus and hypophysis of great apes.

We studied the distribution of neuropeptide Y (NPY) immunoreactivity in the infundibular nucleus and the hypophysis of the chimpanzee, gorilla, and orangutan. Using antibodies developed in rabbit against synthetic porcine NPY, we found numerous NPY-immunoreactive neuronal somata in the infundibular nucleus; this nucleus was also filled with short NPY-positive processes and an abundance of punctate structures that could be indicative of synaptic terminals. Numerous varicose NPY-positive fibers were concentrated in the upper infundibular stem in association with capillary loops of the portal vasculature and with the long portal vessels. Bundles of long varicose fibers ran down the infundibular stem, some appearing to terminate in the lower stem in the vicinity of short portal vessels. The bulbous infundibular process contained only sparsely distributed fibers; they were mostly concentrated near vessels at the border between the infundibular process and the anterior pituitary gland, where the fibers often terminated in a spray-like fashion near blood vessels. No NPY immunoreactivity was seen in the anterior pituitary gland. These results provide anatomical evidence for the release of NPY into the portal vasculature of great apes.

The interaction of primate transferrins with receptors on bacteria pathogenic to humans.

The binding of primate transferrins by receptors in the human pathogens Neisseria meningitidis, Moraxella (Branhamella) catarrhalis, and Haemophilus influenzae was assessed and compared with the binding of anti-human transferrin monoclonal antibodies by primate transferrins. In competitive binding assays the three pathogens showed identical specificity for primate transferrins. Only human, gorilla, chimpanzee and orangutan sera were capable of blocking binding of labelled human transferrin. Direct binding assays and affinity isolation of receptor proteins confirmed that chimpanzee transferrin, but not rhesus monkey transferrin, was capable of effectively binding to the bacterial receptors. Five distinct patterns of binding were seen when five anti-human transferrin monoclonal antibodies were reacted with the primate transferrins and these patterns reflected phylogenetic relatedness of these species to humans. A monoclonal antibody which showed transferrin-binding specificity identical to that seen with the bacterial receptors was found to block binding of human transferrin by receptors in the three bacterial species.

Phenotypic diversity of the cellular 1,25-dihydroxyvitamin D3-receptor interaction among different genera of New World primates.

High serum of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] concentrations and target organ resistance to the hormone are characteristic findings in some New World primates (platyrrhines). We examined the abilities of cultural dermal fibroblasts from individual platyrrhines of four different genera, Aotus, Alouatta, Pithecia, and Saguinus, to internalize and respond to 1,25-(OH)2D3 in an attempt to identify possible phenotypic heterogeneity in the 1,25-(OH)2D3-receptor interaction among them. Results were compared to those from two Old World primates (catarrhines), Pan troglodytes and Pongo pygmaeus. Compared to catarrhine cells, cells from Alouatta, Pithecia, and Saguinus demonstrated 1) a 10-fold decrease in [3H] 1,25-(OH)2D3 internalization capacity; 2) a 2- to 5-fold increase in the apparent internalization constant [3H]1,25-(OH)2D3; and 3) a 3- to 15-fold increase in the 1,25-(OH)2D3 concentration required to elicit half-maximal induction of [3H]25-hydroxyvitamin D3-24-hydroxylating activity (ED50; rank order Sanguinus much greater than Pithecia greater than Alouatta). Although the internalization capacity of cells from two different primates in the genus Aotus was 3- to 4-fold lower than that in catarrhine cells, the internalization constant for hormone and ED50 for 24-hydroxylating activity were similar. These data suggest that the functional 1,25-(OH)2D3-receptor phenotype of the owl monkey, Aotus trivirgatus, is more closely aligned to the catarrhine phenotype than are those of other platyrrhines in the families Cebidae and Callitricidae.

Amylase levels in the tissues and body fluids of several primate species.

1. Serum amylase levels in the gorilla, orang-utan, chimpanzee and squirrel monkey are similar to man. Serum amylase in the Rhesus macaque is almost a whole order of magnitude higher than man. 2. Of the several species tested, all have appreciable amylase in saliva or the parotid gland except the squirrel monkey. 3. High levels of amylase were found in the pancreas of all species tested. Amylase was found in the livers of all species tested. 4. In in vivo experiments with squirrel monkeys, injection of puromycin did not alter serum amylase levels.