Light/fluorescence microscopy of cells & tissues, and electron/cryo-EM imaging of macromolecular structures — a metadata catalog with a durable link back to the source archive, not a hosted image gallery. These are primary research datasets (often multi-GB to multi-TB), so this platform never downloads or stores the underlying imaging data itself. Datasets already in either source archive are ingested via accession paste/CSV at /mirroring by a Continental Admin (no automated harvesting — neither source archive supports geography-filterable search); a dataset not yet in either archive can instead be submitted directly below by any node operator, for Continental Admin review. Either way, whoever submits an accession or a self-submitted dataset is the one asserting African origin — this platform does not verify it.
Diffusible fraction of niche BMP ligand safeguards stem-cell differentiation
BioImage Archive:S-BIAD1008 · Sharif M. Ridwan (University of Connecticut Health Center) · Drosophila repleta
In Drosophila male gonads, niche-derived Decapentaplegic (Dpp) has a role in maintaining stem cells in close proximity but the range of Dpp diffusion and its role has never been tested in the differentiating cells spaced one-cell layer away. Here, using genetically encoded nanobodies called Morphotraps, we physically block Dpp diffusion without interfering with niche-stem cell signaling and find that a diffusible fraction of Dpp is required to ensure differentiation of GSC daughter cells, opposite of its role in maintenance of GSC in the niche. Our work provides an example in which a soluble niche ligand induces opposed cellular responses in stem cells versus differentiating descendants to ensure spatial control of the niche, which may be a common mechanism to regulate tissue homeostasis.
Counterion-enhanced brightness of fluorous-soluble heptamethine cyanine dyes for near- and shortwave infrared fluorescence imaging
BioImage Archive:S-BIAD2526 · (University of California, Los Angeles) · Pericapritermes sp. Cam20-LS-Eri
Fluorescence imaging across the near-infrared (NIR, 700–1000 nm) and shortwave infrared (SWIR, 1000–2000 nm) regions offers significant advantages for biomedical applications, yet photophysical enhancements achieved with NIR and SWIR chromophores observed in solution often fail to translate to complex biological environments. Fluorous-soluble fluorophores, fluorofluorophores, face additional challenges, exhibiting poor brightness and photostability when dissolved in perfluorocarbons (PFCs) due to unfavorable interactions with the fluorous phase. Here, we report counterion exchange as a strategy to enhance the photophysical properties of two heptamethine cyanine fluorofluorophore for NIR and SWIR imaging. Exchanging the small chloride counterion with a large, fluorinated aryl borate counterions significantly improved the brightness (10-fold) and photostability (57-fold) in PFCs. These enhancements were successfully translated across multiple biological systems from macrophage cells to NIR imaging zebrafish retinal tissue and finally to SWIR imaging in mice. These results demonstrate that strategic counterion modification provides a straightforward approach to optimize fluorofluorophores, with solution-phase improvements that translate to in vivo NIR and SWIR imaging.
Asymmetric localization of oskar RNP granules to the oocyte posterior is crucial for abdominal patterning and germline formation in the Drosophila embryo. We show that oskar RNP granules in the oocyte are condensates with solid-like physical properties. Using purified oskar RNA and scaffold proteins Bruno and Hrp48, we confirm in vitro that oskar granules undergo a liquid-to-solid phase transition. Whereas the liquid phase allows RNA incorporation, the solid phase precludes incorporation of additional RNA while allowing RNA-dependent partitioning of client proteins. Genetic modification of scaffold granule proteins, or tethering the intrinsically disordered region of human Fused in Sarcoma (FUS) to oskar mRNA, allowed modulation of granule material properties in vivo. The resulting liquid-like properties impaired oskar localization and translation with severe consequences on embryonic development. Our study reflects how physiological phase transitions shape RNA-protein condensates to regulate localization and expression of a maternal RNA that instructs germline formation.
Asymmetric localization of oskar RNP granules to the oocyte posterior is crucial for abdominal patterning and germline formation in the Drosophila embryo. We show that oskar RNP granules in the oocyte are condensates with solid-like physical properties. Using purified oskar RNA and scaffold proteins Bruno and Hrp48, we confirm in vitro that oskar granules undergo a liquid-to-solid phase transition. Whereas the liquid phase allows RNA incorporation, the solid phase precludes incorporation of additional RNA while allowing RNA-dependent partitioning of client proteins. Genetic modification of scaffold granule proteins, or tethering the intrinsically disordered region of human Fused in Sarcoma (FUS) to oskar mRNA, allowed modulation of granule material properties in vivo. The resulting liquid-like properties impaired oskar localization and translation with severe consequences on embryonic development. Our study reflects how physiological phase transitions shape RNA-protein condensates to regulate localization and expression of a maternal RNA that instructs germline formation.
