Biology subjects

Tulli, S.

Publications and source records attributed to Tulli, S..

5 recordsLinked to original sources

bioRxiv2026

Stimulus identity rather than emotion drives EEG classification on the FACED dataset

Reliable benchmark datasets are critical for advancing EEG-based emotion recognition. The Finer-grained Affective Computing EEG Dataset (FACED) is the largest publicly available EEG emotion dataset (123 subjects, nine emotion categories) and a widely adopted benchmark. We demonstrate that both intra-subject and cross-subject classification on FACED primarily reflects stimulus identity rather than emotion. Using a linear classifier (LinearSVC) and a deep learning model (CLISA), we show that (1) classification performance is comparable for trials where subjects reported feeling versus not feeling the assigned emotion; (2) accuracy drops when stimulus-assigned labels are replaced with individual self-reports; and (3) accuracy increases when reducing to one video per emotion despite discarding two-thirds of the data. These results reflect three design choices in FACED: few stimuli per category, stimulus-assigned labels, and within-video temporal splits for cross-validation. Together, these make the dataset susceptible to temporal autocorrelation and stimulus-identity confounds. To guide future work, we propose five recommendations -- spanning stimulus diversity, temporal independence, and label validation -- for emotion-decoding study designs that mitigate these confounds.

neuroscience↗

bioRxiv2026

Activation of the bridge-like lipid transfer protein Atg2 by Atg1-mediated phosphorylation

Bridge-like lipid transfer proteins (BLTPs) have emerged as major contributors to lipid flux and thus cellular organization. BLTPs harbor a hydrophobic channel connecting two membranes to enable the bulk flow of lipids between them. The regulation of BLTPs is incompletely understood. Employing in vitro reconstitution, molecular dynamics simulations, and cell biology, we discovered that the BLTP Atg2, which mediates lipid transfer during autophagosome biogenesis, is activated by the Atg1 kinase. Atg1 phosphorylates two serines in the N-terminal region of Atg2. This triggers membrane binding and opening of the channel to enable lipid transfer. The Atg1 kinase complex is localized to the endoplasmic reticulum through binding of its Atg13 subunit to the VAP protein Scs2. Phosphorylated Atg2 can subsequently establish contacts with Atg9 vesicles. Our study delineates a pathway for the Atg1 kinase mediated activation of the BLTP Atg2 to establish membrane contact site formation and lipid flux.

cell biology↗

bioRxiv2025

Yomix: An Interactive Tool for the Exploration of Low-Dimensional Embeddings in Omics Data

SummaryIn the analysis of diverse omics data, a common and important preliminary step involves computing low-dimensional embeddings using techniques such as PCA, UMAP, t-SNE, or variational autoencoders. These embeddings provide a global overview of sample distributions and their relationships, often serving as the basis for formulating biological hypotheses. To facilitate rapid and intuitive exploration of such low-dimensional embeddings, we developed Yomix, an interactive omics-agnostic visualization and data exploration tool. Yomix enables users to flexibly define subsets of interest using a lasso selection tool, instantly compute their feature signatures, and compare their distributions. Yomix is a fast and efficient tool for interactive exploration of diverse omics datasets. Availability and ImplementationYomix and its documentation are publicly available at https://github.com/perrin-isir/yomix.

bioinformatics↗

bioRxiv2023

Faa1 membrane binding drives positive feedback in autophagosome biogenesis via fatty acid activation

Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy this material is encapsulated in double membrane vesicles termed autophagosomes, which form from precursors referred to as phagophores. Phagophores grow by lipid influx from the endoplasmic reticulum into Atg9-positive compartments and local lipid synthesis provides lipids for their expansion. How phagophore nucleation and expansion are coordinated with lipid synthesis is unclear. Here, we show that Faa1, an enzyme activating fatty acids, is directly recruited to Atg9 vesicles. We further show that Faa1 binds to negatively charged membranes. We define the membrane binding surface in Faa1 and show that membrane binding is required for its enzymatic activity. In cells, membrane binding by Faa1 is required for its recruitment to phagophores and promotes autophagosome biogenesis. Our results suggest a positive feedback loop coupling phagophore nucleation and expansion to lipid synthesis. SummaryBaumann, Achleitner, Tulli et al. dissect Faa1 function and recruitment during autophagy. They discover that Faa1 directly binds membranes via a positively charged surface. This is a prerequisite for Faa1s enzymatic activity sustaining autophagosome biogenesis.

biochemistry↗

bioRxiv2022

Parallel phospholipid transfer by Vps13 and Atg2 determines autophagosome biogenesis dynamics

During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modelling predicts the majority of autophagosomal phospholipids is derived from highly efficient non-vesicular phospholipid transfer (PLT) across phagophore-ER contacts (PERCS). Currently, the phagophore-ER tether Atg2 is the only PLT protein known to drive phagophore expansion in vivo. Here, our quantitative live-cell-imaging analysis reveals poor correlation between duration and size of forming autophagosomes and number of Atg2 molecules at PERCS of starving yeast cells. Strikingly, we find Atg2-mediated PLT is non-rate-limiting for autophagosome biogenesis, because membrane tether and PLT protein Vps13 localizes to the rim and promotes expansion of phagophores in parallel with Atg2. In the absence of Vps13, the number of Atg2 molecules at PERCS determines duration and size of forming autophagosomes with an apparent in vivo transfer rate of ~200 phospholipids per Atg2 molecule and second. We propose conserved PLT proteins cooperate in channeling phospholipids across organelle contact sites for non-rate-limiting membrane assembly during autophagosome biogenesis.

cell biology↗