Biology subjects

Hsu, M.-T.

Publications and source records attributed to Hsu, M.-T..

3 recordsLinked to original sources

bioRxiv2025

Unusual Ecofunctional Traits of Endozoicomonas: A Pan-Genomic Perspective

BackgroundEndozoicomonas is a widely distributed genus of marine bacteria, associated with various marine organisms, and recognized for its ecological importance in host health, nutrient cycling, and disease dynamics. Despite its significance, genomic features of Endozoicomonas remain poorly characterized due to limited availability of high-quality genome assemblies. ResultsIn this study, we sequenced 5 novel Endozoicomonas strains and re-sequenced 1 known strain to improve genomic resolution. By integrating these 6 high-quality genomes with 31 others that were publicly available, we identified a distinct, coral-associated clade not recognized by the previous two-clade classification. Pan-genomic analysis revealed significant variation in genetic trait distribution among clades. Notably, Endozoicomonas lacks quorum sensing capabilities, suggesting resistance to quorum quenching mechanisms. It also lacks the ability to synthesize and transport vitamin B12, indicating that it is not a primary source of this nutrient for holobionts. A remarkable feature of Endozoicomonas is its abundance of giant proteins, ranging from 15 to 65 kbp. We identified 92 such proteins, which clustered into three major groups based on amino acid similarity, each associated with specialized functions, such as antimicrobial synthesis, exotoxin production, and cell adhesion. Additionally, we explored prophages and CRISPR-Cas systems. We found that Endozoicomonas acquired prophages from diverse sources via infection or other types of gene transfer. Notably, CRISPR-Cas sequences suggest independent evolutionary trajectories from both prophage acquisition and phylogenetic lineage, implying a potential influence of geographic or environmental pressures. ConclusionsThis study provides new insights into the genomic diversity of Endozoicomonas and its genetic adaptation to diverse hosts. Identification of novel genomic features, including deficiencies in B12 synthesis and quorum sensing, the presence of giant proteins, prophages, and CRISPR-Cas systems, underscores its ecological roles in various holobionts. These findings open new avenues for research on Endozoicomonas and its ecological interactions.

ecology↗

bioRxiv2024

Cholinergic interneurons of the dorsomedial striatum mediate winner-loser effects on social hierarchy dynamics in male mice.

Cholinergic interneurons of the dorsomedial striatum may play a role in social hierarchy dynamics. A social hierarchy is an organization of individuals by rank that occurs in social animals. Establishing a new social hierarchy involves flexible behavior in deciding whether to be a winner or loser, experience of winning or losing, and stabilization of rank. The neural circuits underlying such flexible behavior have yet to be fully understood, but previous research indicates that cholinergic interneurons in the dorsomedial striatum play a role in behavioral flexibility. We used the dominance tube test to measure ranking within group housed mice, before and after between-cage competitions using the same test. We found that the experience of winning or losing against mice from different cages not only contributes to new social hierarchies among the competitors, but also causally influences the subsequent social hierarchy among their cage mates in the home cage - supporting the hypothesis of winner-loser effects on later social ranking. To test the hypothesis that cholinergic interneurons contribute to social hierarchy dynamics, we made a selective lesion of cholinergic interneurons in the dorsomedial striatum. The lesion did not prevent social hierarchy formation among pairs of similarly ranked individuals from different cages. However, it reduced the loser effect of external competition on the subsequent home-cage rankings in dominant mice. In light of these results we suggest that cholinergic interneurons in dorsomedial striatum increase the flexibility of social hierarchy dynamics. Significance statementThe effect of winning or losing a competition on subsequent ranking in mouse home cage social hierarchies was examined using the dominance tube test. We found that losing, when dominant mice were defeated by equally ranked mice from another cage, led to decreased social rank in their home cage. Conversely, winning by initially subordinate mice led to increased rank in the home cage social hierarchy. The loser effect on subsequent behavior in dominant mice was reduced after selective lesions of the cholinergic interneurons of the dorsomedial striatum. We suggest that losing might produce these effects by altering the activity of cholinergic interneurons, and thus modulating synaptic plasticity in neural circuits involved in flexible decision making and positive reinforcement.

neuroscience↗

bioRxiv2021

Microbiome restructuring: dominant coral bacterium Endozoicomonas species display differential adaptive capabilities to environmental changes

Bacteria in the coral microbiome play a crucial role in determining coral health and fitness, and the coral host often restructures its microbiome composition in response to external factors. An important but often neglected factor determining this microbiome restructuring is the capacity of microbiome members to adapt to a new environment. To address this issue, we examined how the microbiome structure of Acropora muricata corals changed over 9 months following a reciprocal transplant experiment. Using a combination of metabarcoding, genomics, and comparative genomics approaches, we found that coral colonies separated by a small distance harbored different dominant Endozoicomonas related phylotypes belonging to two different species, including a novel species, Candidatus Endozoicomonas penghunesis 4G, whose chromosome level (complete) genome was also sequenced in this study. Furthermore, the two dominant Endozoicomonas species showed varied adaptation capabilities when coral colonies were transplanted in a new environment. The differential adaptation capabilities of dominant members of the microbiome can a) provide distinct advantages to coral hosts when subjected to changing environmental conditions and b) have positive implications for future reefs.

microbiology↗