Dragonflies are colorful and large-eyed animals strongly dependent on color vision. Here we report an extraordinary large number of opsin genes in dragonflies and their characteristic spatiotemporal expression patterns. Exhaustive transcriptomic and genomic surveys of three dragonflies of the family Libellulidae consistently identified 20 opsin genes, consisting of 4 nonvisual opsin genes and 16 visual opsin genes of 1 UV, 5 short-wavelength (SW), and 10 long-wavelength (LW) type. Comprehensive transcriptomic survey of the other dragonflies representing an additional 10 families also identified as many as 15-33 opsin genes. Molecular phylogenetic analysis revealed dynamic multiplications and losses of the opsin genes in the course of evolution. In contrast to many SW and LW genes expressed in adults, only one SW gene and several LW genes were expressed in larvae, reflecting less visual dependence and LW-skewed light conditions for their lifestyle under water. In this context, notably, the sand-burrowing or pit-dwelling species tended to lack SW gene expression in larvae. In adult visual organs: (i) many SW genes and a few LW genes were expressed in the dorsal region of compound eyes, presumably for processing SW-skewed light from the sky; (ii) a few SW genes and many LW genes were expressed in the ventral region of compound eyes, probably for perceiving terrestrial objects; and (iii) expression of a specific LW gene was associated with ocelli. Our findings suggest that the stage-and region-specific expressions of the diverse opsin genes underlie the behavior, ecology, and adaptation of dragonflies.dragonfly | opsin | color vision | molecular evolution

The Scaly-foot Snail, Chrysomallon squamiferum, presents a combination of biomineralised features, reminiscent of enigmatic early fossil taxa with complex shells and sclerites such as sachtids, but in a recently-diverged living species which even has iron-infused hard parts. Thus the Scaly-foot Snail is an ideal model to study the genomic mechanisms underlying the evolutionary diversification of biomineralised armour. Here, we present a high-quality wholegenome assembly and tissue-specific transcriptomic data, and show that scale and shell formation in the Scaly-foot Snail employ independent subsets of 25 highly-expressed transcription factors. Comparisons with other lophotrochozoan genomes imply that this biomineralisation toolkit is ancient, though expression patterns differ across major lineages. We suggest that the ability of lophotrochozoan lineages to generate a wide range of hard parts, exemplified by the remarkable morphological disparity in Mollusca, draws on a capacity for dynamic modification of the expression and positioning of toolkit elements across the genome.

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The spectrum of the morphologic phenotypes and pathogenic RP1L1 variants was documented in a well-characterized Japanese cohort with OMD. A unique motif including six amino acids (1196-1201) downstream of the doublecortin domain could be a hot spot for RP1L1 pathogenic variants. The significant association of the morphologic phenotypes and genotypes indicates that there are two types of pathophysiology underlying the occult macular dysfunction syndrome: a hereditary OMD with the classical phenotype (Miyake's disease), and a nonhereditary OMD-like syndrome with progressive occult maculopathy.