The Effect of Visual Articulatory Cues on the Identification of Mandarin Tones by Children With Cochlear Implants.

PURPOSE: This study explored the facilitatory effect of visual articulatory cues on the identification of Mandarin lexical tones by children with cochlear implants (CIs) in both quiet and noisy environments. It also explored whether early implantation is associated with better use of visual cues in tonal identification. METHOD: Participants included 106 children with CIs and 100 normal-hearing (NH) controls. A tonal identification task was employed using a two-alternative forced-choice picture-pointing paradigm. Participants' tonal identification accuracies were compared between audio-only (AO) and audiovisual (AV) modalities. Correlations between implantation ages and visual benefits (accuracy differences between AO and AV modalities) were also examined. RESULTS: Children with CIs demonstrated an improved identification accuracy from AO to AV modalities in the noisy environment. Additionally, earlier implantation was significantly correlated with a greater visual benefit in noise. CONCLUSIONS: These findings indicated that children with CIs benefited from visual cues on tonal identification in noise, and early implantation enhanced the visual benefit. These results thus have practical implications on tonal perception interventions for Mandarin-speaking children with CIs.

LLPS of FXR proteins drives replication organelle clustering for ß-coronaviral proliferation.

ß-Coronaviruses remodel host endomembranes to form double-membrane vesicles (DMVs) as replication organelles (ROs) that provide a shielded microenvironment for viral RNA synthesis in infected cells. DMVs are clustered, but the molecular underpinnings and pathophysiological functions remain unknown. Here, we reveal that host fragile X-related (FXR) family proteins (FXR1/FXR2/FMR1) are required for DMV clustering induced by expression of viral non-structural proteins (Nsps) Nsp3 and Nsp4. Depleting FXRs results in DMV dispersion in the cytoplasm. FXR1/2 and FMR1 are recruited to DMV sites via specific interaction with Nsp3. FXRs form condensates driven by liquid-liquid phase separation, which is required for DMV clustering. FXR1 liquid droplets concentrate Nsp3 and Nsp3-decorated liposomes in vitro. FXR droplets facilitate recruitment of translation machinery for efficient translation surrounding DMVs. In cells depleted of FXRs, SARS-CoV-2 replication is significantly attenuated. Thus, SARS-CoV-2 exploits host FXR proteins to cluster viral DMVs via phase separation for efficient viral replication.

Structural Insights into the Distortion of the Ribosomal Small Subunit at Different Magnesium Concentrations.

Magnesium ions are abundant and play indispensable functions in the ribosome. A decrease in Mg2+ concentration causes 70S ribosome dissociation and subsequent unfolding. Structural distortion at low Mg2+ concentrations has been observed in an immature pre50S, while the structural changes in mature subunits have not yet been studied. Here, we purified the 30S subunits of E. coli cells under various Mg2+ concentrations and analyzed their structural distortion by cryo-electron microscopy. Upon systematically interrogating the structural heterogeneity within the 1 mM Mg2+ dataset, we observed 30S particles with different levels of structural distortion in the decoding center, h17, and the 30S head. Our model showed that, when the Mg2+ concentration decreases, the decoding center distorts, starting from h44 and followed by the shifting of h18 and h27, as well as the dissociation of ribosomal protein S12. Mg2+ deficiency also eliminates the interactions between h17, h10, h15, and S16, resulting in the movement of h17 towards the tip of h6. More flexible structures were observed in the 30S head and platform, showing high variability in these regions. In summary, the structures resolved here showed several prominent distortion events in the decoding center and h17. The requirement for Mg2+ in ribosomes suggests that the conformational changes reported here are likely shared due to a lack of cellular Mg2+ in all domains of life.