Molecular features of hookworm larvae (Necator spp.) raised by coproculture from Ugandan chimpanzees and Gabonese gorillas and humans.

Species composition of Necator hookworms was surveyed in (i) Ugandan chimpanzees living around farms and villages at Bulindi, (ii) Gabonese gorillas under habituation in Moukalaba-Doudou National Park (MDNP), and (iii) Gabonese villagers living adjacent to MDNP. Internal transcribed spacers (ITS) of rDNA and partial cytochrome c oxidase subunit 1 (Cox1) gene of mtDNA were analyzed from larvae obtained by coproculture. Three ITS types (I, II and III) and three Cox1 haplotype groups (A, B and C) were demonstrated. ITS type I and Cox1 haplotype group A, representing Necator americanus, were demonstrated in the hookworm larvae from Gabonese gorillas and humans, but not from Ugandan chimpanzees. Type II and haplotype groups B and C, presumably representing N. gorillae, were found in larvae from Ugandan chimpanzees and Gabonese gorillas and humans. These features were overall similar with those found previously in the Central African Republic. Meanwhile, type III was proven in a larva from a Gabonese gorilla as the first demonstration from a non-human primate. Cox1 haplotypes obtained from Ugandan chimpanzees formed a subgroup within group B, presumably reflecting dispersal and diversification processes of the apes.

Behavioral Variation in Gorillas: Evidence of Potential Cultural Traits.

The question of whether any species except humans exhibits culture has generated much debate, partially due to the difficulty of providing conclusive evidence from observational studies in the wild. A starting point for demonstrating the existence of culture that has been used for many species including chimpanzees and orangutans is to show that there is geographic variation in the occurrence of particular behavioral traits inferred to be a result of social learning and not ecological or genetic influences. Gorillas live in a wide variety of habitats across Africa and they exhibit flexibility in diet, behavior, and social structure. Here we apply the 'method of exclusion' to look for the presence/absence of behaviors that could be considered potential cultural traits in well-habituated groups from five study sites of the two species of gorillas. Of the 41 behaviors considered, 23 met the criteria of potential cultural traits, of which one was foraging related, nine were environment related, seven involved social interactions, five were gestures, and one was communication related. There was a strong positive correlation between behavioral dissimilarity and geographic distance among gorilla study sites. Roughly half of all variation in potential cultural traits was intraspecific differences (i.e. variability among sites within a species) and the other 50% of potential cultural traits were differences between western and eastern gorillas. Further research is needed to investigate if the occurrence of these traits is influenced by social learning. These findings emphasize the importance of investigating cultural traits in African apes and other species to shed light on the origin of human culture.

Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon.

African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called 'bais', are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources.

Sharing fruit of Treculia africana among western gorillas in the Moukalaba-Doudou National Park, Gabon: preliminary report.

We report the first 18 observed cases of fruit (Treculia africana) transfer among western lowland gorillas (Gorilla gorilla gorilla) in Moukalaba-Doudou National Park, Gabon. The fruit transfer occurred during our observations of a habituated group of gorillas in 2010 and 2013. Pieces of the fruits were transferred among adults and immatures, and three cases involved a silverback male. Once an individual picked up a fallen fruit of Treculia africana, other members of the group approached the possessor, who laid pieces of the fruits nearby and tolerated the others getting them. Agonistic interaction was rarely observed between the possessor and the non-possessor. Only the silverback male seemed to force another gorilla, a subadult male, to relinquish the fruit on the ground. He tolerated an adult female taking a piece of fruit on his leg and copulated with her on the following days. From these preliminary observations, most interactions over the fruit of Treculia africana among western gorillas in Moukalaba were not active transfer by the possessor but probably passive sharing. They were not only interpreted as a means of acquiring foraging skills by immatures (Nowell and Fletcher 2006) but also similar to behaviors observed in chimpanzees and bonobos in various social contexts.

Assessment of landscape-scale distribution of sympatric great apes in African rainforests: concurrent use of nest and camera-trap surveys.

Information on the distribution and abundance of sympatric great apes (Pan troglodytes troglodytes and Gorilla gorilla gorilla) are important for effective conservation and management. Although much research has been done to improve the precision of nest-surveys, trade-offs between data-reliability and research-efficiency have not been solved. In this study, we used different approaches to assess the landscape-scale distribution patterns of great apes. We conducted a conventional nest survey and a camera-trap survey concurrently, and checked the consistency of the estimates. We divided the study area (ca. 500 km²), containing various types of vegetation and topography, into thirty 16-km² grids (4 km × 4 km) and performed both methods along 2-km transects centered in each grid. We determined the nest creator species according to the definitions by Tutin & Fernandez [Tutin & Fernandez, 1984, Am J Primatol 6:313-336] and estimated nest-site densities of each species by using the conventional distance-sampling approach. We calculated the mean capture rate of 3 camera traps left for 3 months at each grid as the abundance index. Our analyses showed that both methods provided roughly consistent results for the distribution patterns of the species; chimpanzee groups (parties) were more abundant in the montane forest, and gorilla groups were relatively homogeneously distributed across vegetation types. The line-transect survey also showed that the number of nests per nest site did not vary among vegetation types for either species. These spatial patterns seemed to reflect the ecological and sociological features of each species. Although the consistent results may be largely dependent on site-specific conditions (e.g., high density of each species, distinct distribution pattern between the two species), conventional nest-surveys and a subsequent check of their consistency with independent estimates may be a reasonable approach to obtain certain information on the species distribution patterns. Further analytical improvement is necessary for camera-traps to be considered a stand-alone method.

Male genetic structure and paternity in western lowland gorillas (Gorilla gorilla gorilla).

The male dispersal patterns of western lowland gorillas (WLGs, Gorilla gorilla gorilla) are not well understood. To determine whether most silverbacks stay close to their relatives, we analyzed autosomal and Y-chromosomal microsatellites (STRs) in wild WLGs at Moukalaba, Gabon. We obtained STR genotypes for 38 individuals, including eight silverbacks and 12 adult females in an approximately 40 km(2) area. Among them, 20 individuals were members of one identified group (Group Gentil; GG), including one silverback and six adult females. The silverback sired all 13 of the offspring in GG and no Y-STR polymorphism within GG was found, as expected in a one-male group structure. Over all silverbacks sampled, Y-STR diversity was high considering the limited sampling area, and silverbacks with similar Y-STR haplotypes were not always located in nearby areas. Although the misclassification rate of kinship estimates in this study was not negligible, there were no kin dyads among all silverbacks sampled. These results suggest that silverbacks born in the same group do not stay close to each other after maturation. The Y-STR diversity in this study was similar to that of a previous study conducted in an area that was approximately 150 times larger than our study area. Similarity of WLG Y-STR diversity between studies at different sampling scales suggests that male gene flow may not be geographically limited. These results suggest that WLG males normally disperse from their natal areas after maturation, at least, in Moukalaba.

Dehydroabietic acid activates peroxisome proliferator-activated receptor-γ and stimulates insulin-dependent glucose uptake into 3T3-L1 adipocytes.

Dehydroabietic acid (DAA) is a food-derived terpenoid with various bioactivities. Our previous study has revealed that DAA activates peroxisome proliferator-activated receptor-γ (PPARγ) in luciferase assay and suppresses chronic inflammation in obese adipose tissues. In this study, we examined the effects of DAA on adipocyte differentiation. DAA treatment stimulated the adipocyte differentiation of 3T3-L1 preadipocytes. The DAA treatment increased the mRNA expression levels of adipocyte differentiation marker genes such as aP2, lipoprotein lipase (LPL), and PPARγ. In particular, the expression level of adiponectin, which is an adipocytokine with stimulatory effects on insulin sensitivity, was increased at both the mRNA and protein levels by the DAA treatment. Moreover, the DAA treatment stimulated insulin-dependent glucose uptake into differentiated 3T3-L1 adipocytes. These findings indicate that DAA stimulates adipocyte differentiation and insulin sensitivity in 3T3-L1 cells, suggesting that DAA is a valuable food-derived compound for the management of metabolic syndrome.

Luteolin, a food-derived flavonoid, suppresses adipocyte-dependent activation of macrophages by inhibiting JNK activation.

Interaction between adipocytes and macrophages contributes to the development of insulin resistance in obese adipose tissues. In this study, we examined whether luteolin, food-derived flavonoid, could suppress the production of inflammatory mediators of the interaction between adipocytes and macrophages. Experiments using a coculture system of adipocytes and macrophages showed that luteolin suppressed the production of inflammatory mediators. In addition, activated macrophages were targets for the suppressive effect of luteolin. Luteolin inhibited the phosphorylation of JNK and suppressed the production of inflammatory mediators in the activated macrophages. The findings indicate that luteolin can inhibit the interaction between adipocytes and macrophages to suppress the production of inflammatory mediators, suggesting that luteolin is a valuable food-derived compound for the treatment of metabolic syndrome.

Bed and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, Gabon.

In this paper we describe bed (nest) and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, south-eastern Gabon. During an eight-month study 44 bed sites and 506 beds were found. Among these, 38.6% of bed sites and 4.1% of beds were reused. We analyzed the monthly frequency of bed-site reuse in relation to rainfall, fruit abundance, and fruit consumption by the gorillas. The different frequency of bed-site reuse in the rainy and dry seasons was not significant. More bed-site reuse was observed during the fruiting season than during the non-fruiting season. Results from fecal analysis suggested that gorillas ate more fruit in the fruiting season than in the non-fruiting season. The frugivorous diet of western gorillas may possibly cause gorillas to stay in some areas and, consequently, reuse their bed sites. Reuse of bed sites by gorillas suggests their frequent return to an area where preferred fruit is readily available. A higher percentage of arboreal beds may also affect bed-site reuse, because of the shortage of bed material.