Discontinuous transition between Zundel and Eigen for H5O2^+

The hydrated-proton structure is critical for understanding the proton transport in water.However,whether the hydrated proton adopts Zundel or Eigen structure in solution has been highly debated in the past several decades.Current experimental techniques cannot directly visualize the dynamic structures in situ,while the available theoretical results on the infrared(IR)spectrum derived from current configurational models cannot fully reproduce the experimental results and thus are unable to provide their precise structures.In this work,using H5O2^+ as a model,we performed first-principles calculations to demonstrate that both the structural feature and the IR frequency of proton stretching,characteristics to discern the Zundel or Eigen structures,evolve discontinuously with the change of the O–O distance.A simple formula was introduced to discriminate the Zundel,Zundel-like,and Eigen-like structures.This work arouses new perspectives to understand the proton hydration in water.

Both host and diet shape bacterial communities of predatory mites

Microbial communities,derived from food,ambient,and inner,can affect host ecological adaption and evolution.Comparing with most phytophagous arthropods,predators may have more opportunities to develop specific microbiota depending on the level of prey specialization.To explore how diet sources affect host microbial communities and vary across predator species,we considered 3 types of predators from Phytoseiidae(Acari:Mesostigmata):polyphagous(Amblyseius orientalis Ehara,Neoseiulus barkeri Hughes,and Amblyseius swirski Athias-Henrio),oligophagous(Neoseiulus californicus McGregor),and monophagous(Phytoseiulus persimilis Athias-Henriot)predatory mites.The polyphagous species were fed on 2 types of diets,natural prey and alternative prey.By using 16S rRNA sequencing,we found that diet was the main source of microbiota in predatory mites,while there was no clear pattern affected by prey specialization.Among 3 polyphagous predators,host species had a larger impact than prey on microbial composition.Unlike A.orientalis or N.barkeri which showed consistency in their microbiota,prey switching significantly affectedβ-diversity of bacterial composition in A.swirskii,with 56%of the microbial alteration.In short,our results confirmed the substantial influence of diet on host microbial construction in predatory species,and highlighted species differences in shaping the microbiota which are not necessarily related to prey specialization.