Utilization of Sasa borealis seeds by Japanese field mouse: discovery of small-seed caching

Bambusoideae are well-known for their large-scale flowering, seeding, and death events that occur after a vegetative phase that can often last for decades. These events are a valuable resource for many animals. Their mast seeding, in particular, affects rodent populations although the causal relationship between them is speculative. Moreover, the species of animals that utilize this resource also remains unclear. Therefore, this study aimed to examine the interaction between mast seeding plants and animals by conducting a feeding test using the seeds of a dwarf bamboo species (Sasa borealis) at different seasons and in different forest types. The results revealed that two mouse species, Apodemus speciosus and A. argenteus, utilized the seeds. They both predated as well as removed and sometimes buried the seeds, exhibiting small-seed caching behavior. Furthermore, A. speciosus was found to exhibit higher seed predation at covered sites and switching to removal behavior at the more exposed, open sites, while A. argenteus showed no distinguishable trends. Additionally, A. speciosus utilized the seeds less frequently in fall than in summer, suggesting a shift in diet towards acorns when available. Collectively, the results of this study provide novel insights into the interaction between mast seeding plants and the animals that utilize them

Host selection of hematophagous leeches (Haemadipsa japonica): Implications for iDNA studies

The development of an efficient and cost‐effective method for monitoring animal populations or biodiversity is urgently needed, and invertebrate‐derived DNA (iDNA) may offer a promising tool for assessing the diversity and other ecological information of vertebrates. We studied the host species of a hematophagous leech (Haemadipsa japonica) in Yakushima by genetic barcoding and compared the results with those for mammal composition revealed by camera trapping. We analyzed 119 samples using two sets of primers by Sanger sequencing and one set of primer by next generation sequencing. The proportion of the samples that were successfully sequenced and identified to at least one species was 11.8–24.3%, depending on the three different methods. In all of these three methods, most of the samples were identified as sika deer (18/20, 6/15 and 16/29) or human (2/20, 7/15 and 21/29). The nonhuman mammal host species composition was significantly different from that estimated by camera trapping. Sika deer was the main host, which may be related with their high abundance, large body size and terrestriality. Ten samples included DNA derived from multiple species of vertebrates. This may be due to the contamination of human DNA, but we also found DNA from deer, Japanese macaque and a frog in the same samples, suggesting the mixture of the two meals in the gut of the leech. Using H. japonica‐derived iDNA would not be suitable to make an inventory of species, but it may be useful to collect genetic information on the targeted species, due to their high host selectivity

Emulsification Using Highly Hydrophilic Surfactants Improves the Absorption of Orally Administered Coenzyme Q10

Coenzyme Q10 (CoQ10) is an essential component in the electron-transport systems of mitochondria and bacteria and is often used as a supplementary treatment for some diseases. We previously reported that the bioavailability of CoQ10 powder was less than 10%. In this study, we investigated various preparations to improve the intestinal absorption of CoQ10 with focus on the effect of emulsification. We prepared a suspension and some emulsions with four types of surfactants and investigated the plasma concentration profile after oral administration to rats. The absorption of CoQ10 was improved by an emulsion formulation although there was little absorption of CoQ10 when a suspension was administered. However, little CoQ10 was absorbed in the bile duct-ligated group even when the emulsion formulation was administered (about 50% of the control group). Bile and emulsion formulation are essential for absorption of CoQ10. When the preparations containing Tween20 (polysorbate (20) sorbitan monolaurate) and Tween80 (polyoxyethylene (20) sorbitan monooleate) were administered, plasma concentrations of CoQ10 were higher than those obtained with preparations containing Tween65 (polyoxyethylene (20) sorbitan tristearate) and Span20 (sorbitan monolaurate). Tween20 and Tween80 have higher hydrophile-lipophile balance (HLB) values than those Tween65 and Span20. Our study suggests that highly lipophilic compounds like CoQ10 would diffuse the unstirred water layer and would easily access the intestinal apical membrane by an emulsion containing a surfactant with a high HLB value. Attention must be given to CoQ10 supplementation for patients whose bile is not excreted to the intestine such as patients with cholestasis