SACHET: seeded contour tracking measures Rab conversion kinetics on individual endosomes in live cells
- 1Department of Biosciences, University of Oslo
Abstract
Membrane-labeled endosomes appear as hollow rings in a projection; they move, deform and exchange their coat, which population trackers (tools that detect every object of one kind and link the detections across frames) are not designed to follow. Here we introduce SACHET (Seeded Adaptive Contour & Hollow Endosome Tracking), a human-supervised Fiji tool that tracks one endosome at a time. On simulated ground truth it localizes the center to 10 nm, recovers transition time constants and lags without bias and holds the target among touching neighbors; comparisons with tuned TrackMate and Cellpose delineate where each is superior. In crowded spinning-disk projections, TrackMate followed one of seven marked Rab5-to-Rab7 conversions; supervised SACHET followed all 37. SACHET thus provides a stable per-endosome frame in which membrane morphology and protein exchange can be quantified: in five cell lines the conversion toggles like a digital switch within seconds to minutes, differing between lines.
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BibTeX
@misc{margadant2026sachet,
title = {{SACHET: seeded contour tracking measures Rab conversion kinetics on individual endosomes in live cells}},
author = {F. Margadant and A.-C. Borchers and D. Mateus and A. V. Rodseth and V. Manovaseegaran and X. Xu and M. P. Sheetz and O. Bakke and X. Hu},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.30.763220},
url = {https://www.biorxiv.org/content/10.64898/2026.10.30.763220v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - SACHET: seeded contour tracking measures Rab conversion kinetics on individual endosomes in live cells
AU - F. Margadant
AU - A.-C. Borchers
AU - D. Mateus
AU - A. V. Rodseth
AU - V. Manovaseegaran
AU - X. Xu
AU - M. P. Sheetz
AU - O. Bakke
AU - X. Hu
PY - 2026
DA - 2026/10/30
PB - bioRxiv
DO - 10.64898/2026.10.30.763220
UR - https://www.biorxiv.org/content/10.64898/2026.10.30.763220v1
AB - Membrane-labeled endosomes appear as hollow rings in a projection; they move, deform and exchange their coat, which population trackers (tools that detect every object of one kind and link the detections across frames) are not designed to follow. Here we introduce SACHET (Seeded Adaptive Contour & Hollow Endosome Tracking), a human-supervised Fiji tool that tracks one endosome at a time. On simulated ground truth it localizes the center to 10 nm, recovers transition time constants and lags without bias and holds the target among touching neighbors; comparisons with tuned TrackMate and Cellpose delineate where each is superior. In crowded spinning-disk projections, TrackMate followed one of seven marked Rab5-to-Rab7 conversions; supervised SACHET followed all 37. SACHET thus provides a stable per-endosome frame in which membrane morphology and protein exchange can be quantified: in five cell lines the conversion toggles like a digital switch within seconds to minutes, differing between lines.
ER -