Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/mec.16309

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mec.16309

Publisher：Cold Spring Harbor Laboratory  

Anaerobic protists frequently harbour methanogenic archaea, which apparently contribute to the hosts' fermentative metabolism by consuming excess H2. However, the ecological properties of endosymbiotic methanogens remain elusive in many cases. Here we investigated the ecology and genome of the endosymbiotic methanogen of the cellulolytic Cononympha protists in the hindgut of the Formosan termite Coptotermes formosanus. Microscopic and 16S rRNA amplicon sequencing analyses revealed that a single species, designated here 'Candidatus Methanobrevibacter cononymphae', is associated with both Cononympha leidyi and Cononympha koidzumii and that its infection rate in Cononympha cells greatly varied from 0.0 to 99.8% among termite colonies. Fine-scale network analysis indicated that multiple 16S rRNA sequence variants coexisted within a single host cell and that identical variants were present in both Cononympha species and also on the gut wall; 'Ca. Methanobrevibacter cononymphae' is facultatively associated with Cononympha and horizontally taken up. Indeed, transmission electron microscopy showed escape or uptake of methanogens from/by a Cononympha cell. The genome of 'Ca. Methanobrevibacter cononymphae' showed features consistent with its facultative lifestyle: i.e., the genome size (2.7 Mbp) comparable to those of free-living relatives; the pseudogenization of the formate dehydrogenase gene fdhA, unnecessary within the non-formate-producing host cell; the dependence on acetate as an essential carbon source, which is abundant within the host cell; and the presence of a catalase gene, required for colonization on the microoxic gut wall. Our study revealed a versatile endosymbiosis between the methanogen and protists, which may be a strategy responding to changing conditions in the termite gut.

DOI： 10.1101/2024.05.03.592298

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Publishing type：Research paper (scientific journal)   Publisher：The Royal Society  

The fidelity of vertical transmission is a critical factor in maintaining mutualistic associations with microorganisms. The obligate mutualism between termites and intestinal protist communities has been maintained for over 130 million years, suggesting the faithful transmission of diverse protist species across host generations. Although a severe bottleneck can occur when alates disperse with gut protists, how protist communities are maintained during this process remains largely unknown. In this study, we examined the dynamics of intestinal protist communities during adult eclosion and alate dispersal in the termite Reticulitermes speratus . We found that the protist community structure in last-instar nymphs differed significantly from that in workers and persisted intact during adult eclosion, whereas all protists disappeared from the gut during moults between worker stages. The number of protists in nymphs and alates was substantially lower than in workers, whereas the proportion of protist species exhibiting low abundance in workers was higher in nymphs and alates. Using a simulation-based approach, we demonstrate that such changes in the protist community composition of nymphs and alates improve the transmission efficiency of whole protist species communities. This study thus provides novel insights into how termites have maintained mutualistic relationships with diverse gut microbiota for generations.

DOI： 10.1098/rsos.231527

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Other Link： https://royalsocietypublishing.org/doi/full-xml/10.1098/rsos.231527

Language：English   Publishing type：Research paper (scientific journal)  

The emergence of drug-resistant influenza type A viruses (IAVs) necessitates the development of novel anti-IAV agents. Here, we target the IAV hemagglutinin (HA) protein using multivalent peptide library screens and identify PVF-tet, a peptide-based HA inhibitor. PVF-tet inhibits IAV cytopathicity and propagation in cells by binding to newly synthesized HA, rather than to the HA of the parental virus, thus inducing the accumulation of HA within a unique structure, the inducible amphisome, whose production from the autophagosome is accelerated by PVF-tet. The amphisome is also produced in response to IAV infection in the absence of PVF-tet by cells overexpressing ABC transporter subfamily A3, which plays an essential role in the maturation of multivesicular endosomes into the lamellar body, a lipid-sorting organelle. Our results show that the inducible amphisomes can function as a type of organelle-based anti-viral machinery by sequestering HA. PVF-tet efficiently rescues mice from the lethality of IAV infection.

DOI： 10.1038/s41467-019-13974-w

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/femsec/fiy238

Web of Science

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Responsible for pages：168-169   Language：Japanese   Book type：Dictionary, encyclopedia

CiNii Books

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Responsible for pages：390-391   Language：Japanese   Book type：Dictionary, encyclopedia

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Award type：Award from international society, conference, symposium, etc. 

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