Neopterin Levels in Bonobos Vary Seasonally and Reflect Symptomatic Respiratory Infections

As environmental changes exacerbate the threat coming from infectious diseases in wild mammal species, monitoring their health and gaining a better understanding of the immune functioning at the species level have become critically important. Neopterin is a biomarker of cell-mediated immune responses to intracellular infections. We investigated the variation of urinary neopterin (uNeo) levels of wild, habituated bonobos (Pan paniscus) in relation to individual and environmental factors. We used 309 urine samples collected between 2010 and 2018 at the LuiKotale field site, DRC. Based on current knowledge on zoo-housed conspecifics and closely related species, we predicted uNeo levels to increase (1) during infections, (2) with increasing age, (3) over the gestation period and in estrous females; and (4) to vary seasonally. Our results showed uNeo levels varied over a one-year period and increased in individuals showing respiratory symptoms. Contrary to chimpanzees, uNeo levels did not vary with age or female reproductive status, possibly due to our small sample size. Our study provides a baseline for a better understanding of bonobo's immunocompetence in the context of socio-ecological pressures and for monitoring the health of wild populations.

What fecal analyses reveal about Manniophyton fulvum consumption in LuiKotale bonobos (Pan paniscus): A medicinal plant revisited

Observations of animals in the wild can result in the discovery of plants for human medicinal purposes. In this context, our closest relatives, the great apes, are of particular interest. The Euphorbiaceae Manniophyton fulvum possesses both phytochemical and biomechanical properties. Its use in the genus Pan (P. troglodytes; P. paniscus) is thought to be based on its mechanical properties promoting the egestion of intestinal parasites, but additional observations from different habitats where the behavior is performed may shed more light on its true purpose. To improve our understanding of what triggers this behavior, we investigated M. fulvum consumption in wild bonobos at LuiKotale, Democratic Republic of the Congo between December 2018 and July 2020. Specifically, we tested the hypothesis that M. fulvum ingestion is related to gastro-intestinal parasite expulsion. Of 649 focal follows of 37 individuals from two habituated communities, consumption of M. fulvum was observed on 111 days (N = 507), independent of seasons, environmental factors and the plant's availability. A total of 588 fecal samples were assessed for the presence/absence of gastro-intestinal parasites. We found strongyle eggs in 2.89% of samples and their presence was not associated with the ingestion of M. fulvum or environmental conditions. We discuss the importance of seasonality in the life cycle of strongyle species that may influence the pattern of M. fulvum consumption observed at LuiKotale. Our data open additional perspectives concerning behavioral parameters such as the existence of a cultural component when comparing ingestion behavior between communities.

Resonantly Interacting Fermi-Fermi Mixture of ^{161}Dy and ^{40}K

We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of ^{161}Dy and ^{40}K, we identify a broad Feshbach resonance centered at a magnetic field of 217 G. Hydrodynamic expansion profiles in the resonant interaction regime reveal a bimodal behavior resulting from mass imbalance. Lifetime studies on resonance show a suppression of inelastic few-body processes by orders of magnitude, which we interpret as a consequence of the fermionic nature of our system. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.

Accurate Determination of the Dynamical Polarizability of Dysprosium

We report a measurement of the dynamical polarizability of dysprosium atoms in their electronic ground state at the optical wavelength of 1064 nm, which is of particular interest for laser trapping experiments. Our method is based on collective oscillations in an optical dipole trap, and reaches unprecedented accuracy and precision by comparison with an alkali atom (potassium) as a reference species. We obtain values of 184.4(2.4) and 1.7(6) a.u. for the scalar and tensor polarizability, respectively. Our experiments have reached a level that permits meaningful tests of current theoretical descriptions and provides valuable information for future experiments utilizing the intriguing properties of heavy lanthanide atoms.