Chua, K. X. | Search bioRxiv

bioRxiv2024

Localization and function of key axonemal microtubule inner proteins and dynein docking complex members reveal extensive diversity among vertebrate motile cilia

Vertebrate motile cilia are broadly classified as (9+2) or (9+0), based on the presence or absence of the central pair apparatus, respectively. Cryogenic electron microscopy (cryo-EM) analyses of (9+2) cilia have uncovered an elaborate axonemal protein composition; whether these features are relevant to (9+0) cilia remain unclear. We previously demonstrated that Cfap53, a key microtubule inner protein (MIP) as well as centriolar-satellites component, is essential for motility of (9+0), but not (9+2) cilia. Here, we show that in (9+2) cilia, Cfap53 functions redundantly with a paralogous MIP, Mns1. Mns1 localizes to ciliary axonemes, and combined loss of both proteins in zebrafish and mice, caused severe loss of outer dynein arms (ODAs) of (9+2) cilia, significantly affecting their motility. Moreover, using immunoprecipitation, we demonstrate that while Mns1 can self-associate and interact with Cfap53, Cfap53 is unable to self-associate. Finally, we show that multiple additional dynein interacting proteins, such as the ODA docking complex (ODA-DC) members, show strikingly distinct localization patterns between various motile cilia-types. Our findings clarify how paralogous MIPs, Cfap53 and Mns1, function in regulating motility of (9+2) versus (9+0) cilia, and establish that localization pattern of other key motility proteins also differ between these cilia-types, further emphasizing extensive structural variations among these organelles.

developmental biology↗

bioRxiv2023

Dynamics of endogenous and water cortisol release in Asian Seabass Lates calcarifer after acute stress in a farm scale recirculating aquaculture system

Stress in farmed fish is associated with poor feeding, slow growth, disease, and mortality. Therefore, it is essential to closely monitor the stress levels in fish to optimize farming practices which could then enhance productivity and welfare in aquaculture operations. Cortisol, a stress hormone that can be found in the blood, is a reliable biomarker for evaluating fish stress. As blood sampling is highly invasive, alternative cortisol sampling methods such as fin, mucus, and the surrounding water which contains released cortisol, have been proposed as less invasive or non-invasive sampling methods. However, a comprehensive understanding of their temporal dynamics and associations with plasma cortisol levels is still lacking. In this study, we subjected Lates calcarifer, Asian sea bass within a farm-scale (3,000 L tank, 9,000 L system) high-flow rate (8,000 L/hour) Recirculating Aquaculture System (RAS) to an acute handling stress challenge specifically involving chasing and air exposure, and quantified cortisol dynamics both within different biological samples including blood, fin, and mucus and in tank water from multiple sampling points. We showed that handling stress induced an expected increase in plasma and mucosal cortisol, peaking at 1 hour and 24-48 hours, respectively, and that plasma and mucus cortisol were moderately correlated, especially during the stress period. Fin cortisol did not show consistent dynamics. Water cortisol similarly rose, but peaked within 40 minutes from the start of the stressor, in a pattern that was dependent on the site of sampling within the RAS system, likely due to RAS circulation dynamics. Our study is the first to examine the impact of stress on cortisol accumulation and release in Asian Sea bass in a farm-scale RAS, thus complementing existing research on the efficacy of fin, mucus, and water cortisol as stress indicators that could help optimize aquaculture productivity and welfare.

physiology↗