SummaryGut microbiota typically occupy habitats with definable limits/borders that are comparable to oceanic islands. The gut therefore can be regarded as an 'island' for the assembly of microbial communities within the 'sea' of surrounding environments. This study aims to reveal the ecological mechanisms that govern microbiota in the fish gut 'island' ecosystem. Taxonomic compositions, phylogenetic diversity, and community turnover across host development were analyzed via the high-throughput sequencing of 16S rRNA gene amplicons. The results indicate that the Shannon diversity of gut microbiota in the three examined freshwater fish species all significantly decreased with host development, and the dominant bacterial taxa also changed significantly during host development. Null model and phylogenetic-based mean nearest taxon distance (MNTD) analyses suggest that host gut environmental filtering led to the assembly of microbial communities in the fish gut 'island'. However, the phylogenetic clustering of local communities and deterministic processes that governed community turnover became less distinct as the fish developed. The observed mechanisms that shaped fish gut microbiota seemed to be mainly shaped by the gut environment and by some other selective changes accompanying the host development process. These findings greatly enhance our understanding of stage-specific community assembly patterns in the fish gut ecosystem.

Magnetic microrobots can be actuated in fuel-free conditions and are envisioned for biomedical applications related to targeted delivery and therapy in a minimally invasive manner. However, mass fabrication of microrobots with precise propulsion performance and excellent therapeutic efficacy is still challenging, especially in a predictable and controllable manner. Herein, we propose a facile technique for mass production of magnetic microrobots with multiple functions using Spirulina (Sp.) as biotemplate. Core−shell-structured Pd@Au nanoparticles (NPs) were synthesized in Sp. cells by electroless deposition, working as photothermal conversion agents. Subsequently, the Fe 3 O 4 NPs were deposited onto the surface of the obtained (Pd@Au)@Sp. particles via a sol−gel process, enabling them to be magnetically actuated. Moreover, the anticancer drug doxorubicin (DOX) was loaded on the (Pd@Au)/Fe 3 O

To understand how a bacteria-free fish gut ecosystem develops microbiota as the fish ages, we performed a 1-year study on the gut microbiota of hatchling gibel carp (Carassius auratus gibelio). Our results indicate that the gut microbial diversity increases significantly as the fish develop. The gut microbial community composition showed significant shifts corresponding to host age and appeared to shift at two time points despite consistent diet and environmental conditions, suggesting that some features of the gut microbial community may be determined by the host's development. Dietary and environmental changes also seem to cause significant shifts in the fish gut microbial community. This study revealed that the gut microbiota of gibel carp assemble into distinct communities at different times during the host's development and that this process is less affected by the surrounding environment than by the host diet and development. Community phylogenetic analyses based on the net relatedness index further showed that environmental filtering (host selection) deterministically governs the gut microbial community composition. More importantly, the influence of host-associated deterministic filtering tends to weaken significantly over the course of the host's development. However, further studies are needed to assess whether this host development-dependent shift in gut microbiota will still exist under different rearing strategies.

We successfully fabricated a highly anisotropic electrical conductive microcoil/polydimethylsiloxane (PDMS) composite based on helical Spirulina-templated metallic particles using an electric field-induced alignment method. The optimized AC electric field (2 kV/cm, 1 kHz) could efficiently assemble the lightweight conductive microcoils into continuous long chains and form unique end-to-end physical contacts between adjacent particles in the alignment direction, leading to highly conductive channels. Furthermore, the electrical conductivity in the alignment direction reached up to ∼10 S/m for 1 wt % loading and exhibited almost 7-8 orders of magnitude higher than that in perpendicular directions, which is by far the most remarkable conductive anisotropy for anisotropic conductive composites (ACCs). In addition, the anisotropic composites exhibit excellent current-carrying capability in a functional light emitting diode (LED) circuit. Therefore, due to the superior conductive anisotropy and high conductivity, the composites have promising potential in high reliability electrical interconnections and subminiature integrated circuits.

Clarifying mechanisms underlying the ecological succession of gut microbiota is a central theme of gut ecology. Under experimental manipulations of zebrafish hatching and rearing environments, we test our core hypothesis that the host development will overwhelm environmental dispersal in governing fish gut microbial community succession due to host genetics, immunology, and gut nutrient niches. We find that zebrafish developmental stage substantially explains the gut microbial community succession, whereas the environmental effects do not significantly affect the gut microbiota succession from larvae to adult fish. The gut microbiotas of zebrafish are clearly separated according to fish developmental stages, and the degree of homogeneous selection governing gut microbiota succession is increasing with host development. This study advances our mechanistic understanding of the gut microbiota assembly and succession by integrating the host and environmental effects, which also provides new insights into the gut ecology of other aquatic animals.

Uncovering which environmental factors govern community diversity patterns and how ecological processes drive community turnover are key questions related to understand the community assembly. However, the ecological mechanisms regulating long-term variations of bacterioplankton communities in lake ecosystems remain poorly understood. Here we present nearly a decade-long study of bacterioplankton communities from the eutrophic Lake Donghu (Wuhan, China) using 16S rRNA gene amplicon sequencing with MiSeq platform. We found strong repeatable seasonal diversity patterns in terms of both common (detected in more than 50% samples) and dominant (relative abundance >1%) bacterial taxa turnover. Moreover, community composition tracked the seasonal temperature gradient, indicating that temperature is a key environmental factor controlling observed diversity patterns. Total phosphorus also contributed significantly to the seasonal shifts in bacterioplankton composition. However, any spatial pattern of bacterioplankton communities across the main lake areas within season was overwhelmed by their temporal variabilities. Phylogenetic analysis further indicated that 75%-82% of community turnover was governed by homogeneous selection due to consistent environmental conditions within seasons, suggesting that the microbial communities in Lake Donghu are mainly controlled by niche-based processes. Therefore, dominant niches available within seasons might be occupied by similar combinations of bacterial taxa with modest dispersal rates throughout different lake areas.

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Visible-light active photocatalysis under continuous magnetic actuation.