Ancient Myosin Gene Variant Controls Left-Right Shell Coiling in Japanese Snails
Researchers have identified that variation in an unconventional myosin I a/b gene determines whether Japanese Euhadra snails coil their shells to the left or right. Unlike previously studied chirality mutations, both variants are ancient, widespread in wild populations, and cause no apparent harm to the snails. The finding expands the known molecular toolkit for left-right asymmetry and may guide research into how body asymmetry is established across the animal kingdom.
A new study published on bioRxiv reports that left-right chiral variation in Japanese Euhadra snails is controlled by functional differences in a myosin I a/b gene — an unconventional myosin isoform not previously linked to left-right axis specification in any animal. Both the sinistral (left-coiling) and dextral (right-coiling) gene variants are evolutionarily ancient, produce minimal differences in gene expression during early single-cell embryo development, and are not associated with developmental pathology, distinguishing this system from previously studied chirality mutations that are rare and harmful. Phylogenetic analysis and structural modelling suggest that dominant-acting amino acid substitutions in the myosin actin-binding domain and at the motor-level junction were made possible by relaxed evolutionary selection pressure. The research highlights Japanese snails as a uniquely powerful model organism for studying the origins of body asymmetry, given that most animals show invariant chirality. The authors suggest that the key mutation sites identified here should be investigated in other model animals to further clarify the molecular basis of left-right patterning.
What's missing
As a preprint, this study has not yet undergone formal peer review, so findings should be treated as preliminary. The study does not fully resolve the precise molecular mechanism by which the myosin I a/b variants differentially direct chiral cell division in the early embryo.
What different sources said
- bioRxivCenter
An ancient polymorphism in myosin I a/b determines the left-right asymmetry of Japanese snails
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.