Jiaqian Li

Peri-implant immune microenvironment shapes microbial composition and the course of regeneration. Immune signatures show untapped potential in improving the risk-grading for peri-implantitis.

Lysosomes are central players in cellular catabolism, signaling, and metabolic regulation. Cellular and environmental stresses that damage lysosomal membranes can compromise their function and release toxic content into the cytoplasm. Here, we examine how cells respond to osmotic stress within lysosomes. Using sensitive assays of lysosomal leakage and rupture, we examine acute effects of the osmotic disruptant glycyl-L-phenylalanine 2-naphthylamide (GPN). Our findings reveal that low concentrations of GPN rupture a small fraction of lysosomes, but surprisingly trigger Ca 2+ release from nearly all. Chelating cytoplasmic Ca 2+ makes lysosomes more sensitive to GPN-induced rupture, suggesting a role for Ca 2+ in lysosomal membrane resilience. GPN-elicited Ca 2+ release causes the Ca 2+ -sensor Apoptosis Linked Gene-2 (ALG-2), along with Endosomal Sorting Complex Required for Transport (ESCRT) proteins it interacts with, to redistribute onto lysosomes. Functionally, ALG-2, but not its ESCRT binding-disabled ΔGF 122 splice variant, increases lysosomal resilience to osmotic stress. Importantly, elevating juxta-lysosomal Ca 2+ without membrane damage by activating TRPML1 also recruits ALG-2 and ESCRTs, protecting lysosomes from subsequent osmotic rupture. These findings reveal that Ca 2+ , through ALG-2, helps bring ESCRTs to lysosomes to enhance their resilience and maintain organelle integrity in the face of osmotic stress.

The biological pump plays a vital role in exporting organic particles into the deep ocean for long-term carbon sequestration. However, much remains unknown about some of its key microbial players. In this study, Labyrinthulomycetes protists (LP) were used to understand the significance of heterotrophic microeukaryotes in the transport of particulate organic matter from the surface to the dark ocean. Unlike the sharp vertical decrease of prokaryotic biomass, the LP biomass only slightly decreased with depth and eventually exceeded prokaryotic biomass in the bathypelagic layer. Sequencing identified high diversity of the LP communities with a dominance of Aplanochytrium at all depths. Notably, ASVs that were observed in the surface layer comprised ~20% of ASVs and ~60% of sequences in each of the deeper (including bathypelagic) layers, suggesting potential vertical export of the LP populations to the deep ocean. Further analyses of the vertical patterns of the 50 most abundant ASVs revealed niche partitioning of LP phylotypes in the pelagic ocean, including those that could decompose organic detritus and/or facilitate the formation of fast-sinking particles. Overall, this study presents several lines of evidence that the LP can be an important component of the biological pump through their multiple ecotypes in the pelagic ocean.