Volume 227, Issue 4, August 2024

Extracellular vesicles (EV) play increasingly diverse roles during development, physiology, and disease. In vivo studies in the nematode Caenorhabditis elegans have revealed insights into the mechanisms of EV formation and an array of EV functions for the EV-releasing cell or EV-receiving cells. This review summarizes the current state of the art and important directions for future research.

Hedgehog is an important signaling protein in many organisms. Nematodes lack Hedgehog and most of its canonical signaling partners but instead have many divergent Hedgehog-related (Hh-r) secreted proteins and Patched-related transmembrane proteins related to the Hedgehog receptor. The authors show that C. elegans Hh-r proteins are stable components of the apical extracellular matrices that coat and protect external epithelia. These results can explain many phenotypes of Hh-r mutants and highlight ancient connections between Hedgehog proteins and the extracellular matrix.

Cells have rapid and robust repair systems to survive daily damage. This study shows that calcium influx regulates the three distinct Drosophila Annexin recruitment patterns to the cell wound in order to organize an actomyosin ring for efficient wound closure.

Techniques for genetic manipulation in Drosophila melanogaster are powerful but not without limitations. Here, the authors detail a novel approach to achieve strong RNA knockdown in Drosophila using self-cleaving ribozymes. Ribozyme insertion via CRISPR/Cas9 into both nuclear and cytoplasmic noncoding RNAs and a male-specific splice variant of doublesex resulted in cleavage and efficient degradation of 3’ RNA fragments without observable off-target effects. This work demonstrates the potential of self-cleaving ribozymes for gene knockdown in Drosophila.

This work highlights the importance of genome size and chromosome number in assembly assessment. While more than 41,000 eukaryotic genomes are available, only about 15,000 of them have corresponding genome size estimations. This work assesses the completeness of these genome assemblies in terms of deviation from estimated genome size and its relationship to a number of factors and assembly assessments. A new assembly assessment is proposed which is comparable across genomes with varying sizes and architecture.