Highlights d RNA-BisSeq revealed a dynamic RNA m 5 C landscape during zebrafish embryogenesis d Ybx1 preferentially recognizes m 5 C-modified mRNAs d Ybx1 deficiency leads to early gastrulation defects in zebrafish embryos d Ybx1 and Pabpc1a coordinately regulate m 5 C-modified maternal mRNA stability

Self-propelled motors have been developed with promising potential for medical applications. However, most of them have a size range at the microscale, which limits their further research for in vivo experiments. Previously, our group developed nanoscaled motors with a size of around 400 nm with several merits, for example, delivering both hydrophobic and hydrophilic drugs/proteins, using biocompatible fuels while being able to control their motion, and showing adaptive changes of their speed and navigation to changes in the environment. It is also well-known that nanoparticles that are around 20–200 nm in size have advantages in overcoming cellular barriers and being internalized into cells. Therefore, lowering the size range of this stomatocyte nanomotor is crucial. However, the strict control of the size of vesicles in such a low regime as well as their shape transformation into folded stomatocyte structures is not trivial. In this study, we fabricated ultrasmall stomatocyte polymersomes with the size of around 150 nm, which could be a promising carrier for biomedical purposes. We demonstrated that the addition of PEG additive allows for both shape transformation of small polymersomes into stomatocytes and encapsulation of biologics. Biocatalyst catalase was encapsulated in the inner compartment of the nanomotor, protecting the enzyme while providing enough thrust to propel the motors. The ultrasmall stomatocyte motor system allowed propelled motion by converting H2O2 into O2 in the presence of only 2 mM H2O2, and the velocity of motors correlated to the O2 production. Compared to small stomatocyte nanomotors, ultrasmall stomatocyte motors demonstrate enhanced penetration across the vasculature model and increased uptake by HeLa cells in the presence of fuel.

The vertebrate body is formed by cell movements and shape change during embryogenesis. It remains undetermined which maternal signals govern the formation of the dorsal organizer and the body axis. We found that maternal depletion of huluwa, a previously unnamed gene, causes loss of the dorsal organizer, the head, and the body axis in zebrafish and Xenopus embryos. Huluwa protein is found on the plasma membrane of blastomeres in the future dorsal region in early zebrafish blastulas. Huluwa has strong dorsalizing and secondary axis–inducing activities, which require β-catenin but can function independent of Wnt ligand/receptor signaling. Mechanistically, Huluwa binds to and promotes the tankyrase-mediated degradation of Axin. Therefore, maternal Huluwa is an essential determinant of the dorsal organizer and body axis in vertebrate embryos.