Journal of experimental zoology. Part B, Molecular and developmental evolution最新文献

The diverse and colorful patterns found in organisms serve various functions. In Pachyrhynchus weevils, these colors and patterns composed of 3D photonic architectures function as signals for sexual selection and aposematism. Previous study of photonic structure suggests the involvement of specific genes in color regulation in Pachyrhynchus weevils. However, the genes responsible for scale coloring in Pachyrhynchus weevils have remained unknown. In this study, RNA-seq was conducted in P. nobilis at 6 h and 24 h after emergence, comparing elytra (no-scale) and scale tissues during the period of coloring. qPCR validation was performed across three species (P. nobilis, P. sarcitis, and P. orbifer). RNA-seq analysis identified 3172 and 2890 DEGs at 6 h and 24 h after emergence, respectively, with up-regulated DEGs increasing over time. The candidate genes were selected based on functional annotations related to scale development (C-type lectins, cuticle proteins, and Yellow family proteins), and KEGG pathway analysis. qPCR validation revealed species-specific expression patterns: C-type lectin-encoding gene was expressed in P. nobilis and P. sarcitis but absent in P. orbifer, while Hedgehog-like protein-encoding gene was exclusively detected in P. orbifer. Temporal analysis showed significant differences in Wnt signaling pathway between developmental stages in P. orbifer, and marginal significance in calcium signaling pathway gene in P. sarcitis. This study suggests that these specific genes may play roles in color regulation during scale development in Pachyrhynchus weevils, with varying expression at different time points after emergence or among species.

Transcription factors are typically thought to play a limited role in developmental evolution due to their high pleiotropic nature. However, such constraints may be relaxed following gene duplication or when proteins are organized into structural and functional modules, opening avenues for evolutionary innovation. Here, we integrate expression and genomic data to investigate the evolutionary dynamics of Hox gene duplicates in the allotetraploid frog Xenopus laevis. Despite overall conservation across the Hox clusters, we find that HoxB4L has acquired expression during maternally regulated stages and is evolving under positive selection. Protein-level changes include the number, length, and sequence of functionally important protein regions. Our results indicate that HoxB4L has escaped ancestral constraints and is undergoing maternal neofunctionalization as a result of cis-regulatory divergence and structural protein modifications. These findings illustrate how transcription factors can overcome developmental constraints and contribute to novel functions during early development.

Experimental studies have demonstrated that nutritional changes during development can result in phenotypic changes to mammalian cheek teeth. This developmental plasticity of tooth morphology is an example of phenotypic plasticity. Because tooth development occurs through complex interactions between manifold processes, there are many potential mechanisms which can contribute to a tooth's norm of reaction. Determining the identity of those mechanisms and the relative importance of each of them is one of the main challenges to understanding phenotypic plasticity. Quantitative proteomics combined with experimental studies allow for the identification of potential molecular contributors to a plastic response through quantification of expressed gene products. Here, we present the results of a quantitative proteomics analysis of mature upper first molars in Mus musculus from a controlled feeding experiment. Pregnant and nursing mothers were fed either a low-dietary protein (10%) treatment diet or control (20%) diet. Low-dietary protein was not associated with reduced molar size or skull length. However, expression of tooth-related proteins, immune system proteins, and actin-based myosin proteins were significantly altered in our low-dietary protein proteomics sample. The differential expression of immune proteins along with systematic reduction in actin-based myosin protein expression are novel discoveries for tooth proteomics studies. We propose that studies that aim to elucidate specific mechanisms of molar phenotypic plasticity should prioritize investigations into the relationships between IGF regulation and tooth development and actin-based myosin expression and tooth development.

The impact of land-to-water transition on chemosensory genes has been explored in marine tetrapod vertebrates, with scarce data on aquatic insect lineages. Diving beetles (Dytiscidae) are predaceous freshwater insects with strictly aquatic larvae and amphibious adults. Using RNA-seq, we compared the expression of odorant receptors (ORs), gustatory receptors (GRs), ionotropic receptors (IRs), and odorant-binding proteins (OBPs) in the cephalic appendages of larval and adult Cybister lateralimarginalis. Overall, larvae expressed fewer chemosensory genes than adults but larva-specific genes displayed a unique expression pattern, not previously observed in any other holometabolous insect, with five larva-specific ORs all having a close paralogue which is adult-specific, 14 larva-specific IRs all belonging to a single gene expansion in the IR tree, and no larva-specific GR. Expression profiles across appendage types mirrored those in aerial insects, with ORs mainly in antennae, GRs in labial palps, "Antennal class" IRs in antennae, and "Divergent class" IRs in palps. This suggests that the land-to-freshwater transition in this lineage did not involve major changes in deployment of the major families of chemosensory genes among cephalic appendages. Notably, the expression of a substantial repertoire of ORs specifically in the antennae of the larva suggests that hydrophobic chemical cues are important for long-range chemodetection in freshwater, contrary to prevailing views about constraints for chemosensation within a water medium.

Bivalve planktonic development is a critical phase during which larvae must secrete the first calcium carbonate shell, the prodissoconch I (PD I). As PD I formation is in close contact with seawater, this process can be negatively affected by adverse seawater carbonate chemistry. It is hypothesized that bivalves can regulate shell formation under environmental stress through biologically controlled biomineralization involving a complex extracellular shell proteome. However, the plasticity of this regulatory mechanism during PD I development is unknown. We assessed the PD I shell proteome of the Hong Kong oyster (Magallana hongkongensis) in carbonate chemistry that was adverse or favorable for biomineralization to understand the regulatory capacity of larval shell formation. While survival rates were not affected in adverse carbonate chemistry, there were significant changes, including the upregulation of several calcium-binding proteins and downregulation of proton-generating processes and putative calcification inhibitors. With 198 sequences, the oyster larval shell proteome was twice to over six times larger than those reported for other bivalve species at the same developmental stage. However, in adverse carbonate chemistry, the oyster larval shells were thinner and smaller, and protein diversity decreased to 131 sequences, with overall lower functional redundancy and reduced expression of structural proteins, indicating potential trade-offs. The proteomic and shell structural data also suggest that direct cellular control and biologically induced mechanisms, which will require further investigation, may be involved in PD I formation.

Fibroblast growth factor signaling plays a crucial role in various developmental processes and is a key driver of regeneration. In annelids, this pathway is active from the earliest stages of reparative morphogenesis, yet its specific function remains unclear. Here we have functionally examined FGF signaling following the amputation of posterior segments in the marine annelid Alitta virens. We utilized the pharmacological agent SU5402 to inhibit the FGF receptor kinase at different time points. With whole-mount in situ hybridization, we analyzed the expression of regulatory genes that pattern posterior territories (cdx, evx, post2), multipotent/germ cells (vasa, piwi), mesodermal tissues (twist), and segmental boundaries (engrailed). Our findings reveal that FGF signaling is essential for blastema induction by promoting dedifferentiation and proliferation of cells at the wound site, but is not involved in posteriorization. On the contrary, this pathway is crucial for differentiation in the proximal (anterior) part of the regenerative bud, impacting its mesodermal derivatives and segment boundary formation. Comparative analysis suggests that while certain functions of FGF signaling, particularly in mesodermal patterning, are conserved across taxa, its role in posterior axis elongation appears to have evolved specifically within the vertebrate lineage. This study enhances our understanding of the evolutionary origins and functional diversification of FGF signaling in regeneration, positioning A. virens as a valuable model for exploring the complexities of regenerative biology.

Cell proliferation is a key driver of morphogenesis and body plan transformation in multicellular animals, yet its spatial organization remains poorly understood in many non-segmented spiralians. In this study, we examine the dynamics of cell division during larval growth and metamorphosis in the larvae and early juveniles of the phoronid Phoronopsis harmeri, using EdU incorporation, anti-phospho-histone H3 immunostaining, confocal laser scanning microscopy, and electron microscopy. Early larval proliferation is partly regionalized from the outset and becomes progressively more localized toward metamorphosis. We identify a tripartite organization of proliferative activity: (1) posterior ring-shaped domains in the telotroch that persist through metamorphosis and support elongation and anal chamber formation; (2) regional proliferative zones at tentacle bases, preoral and postoral regions; and (3) scattered proliferation driving the expansion of the trunk epidermis. This coexistence of posterior, regional, and scattered patterns underscores the developmental plasticity of phoronids and the diversity of growth strategies within Spiralia. Posterior proliferative domains in phoronids contribute important context to homology–convergence debates on posterior growth across spiralians, but are not decisive by themselves; viewed with the distributed epithelial proliferation, they underscore the coexistence of multiple proliferative programs within a single life cycle. In addition, we identify atypical mitotic characteristics in this species, including unconventional metaphase organization and signs of interkinetic nuclear migration in larval epithelia. Our results suggest that phoronids provide a valuable model for exploring how diverse architectures of cell proliferation contribute to larval growth, body elongation, and morphogenetic compartmentalization in Lophotrochozoa.

The present study reveals the immunolocalization of the MARCKS-like protein in two urodeles and an anuran during the initial stages of appendage regeneration. This acidic protein of 22-32 kDa interacts with the dynamic cytoskeleton of activated keratinocytes and blastema cells and is believed to be among the initial signaling factors stimulating limb regeneration in the axolotl. Bioinformatics controls indicate presence of homologous MARCKS-like proteins also in other amphibian species. The present study aims to generalize the presence of this protein during the first 2-8 days of appendage regeneration in amphibians. In the wound epidermis of the axolotl, the protein is prevalently localized in pale Leydig cells, a mucous cell type described in amphibian epidermis, many of which are present in the regenerating epidermis. A lower immunolabeling is found in the newt wound epidermis but is high in regenerating nerves. In the regenerating tail of frog tadpoles MARCKS-like immunolabeling is present in the wound epidermis, regenerating spinal cord, ganglia and nerves but also with lower intensity in myotubes and in the external layer of notochord. Low to absent MARCKS-like immunoreactivity is instead observed in the normal epidermis and in the wound epidermis of the non-regenerating tadpole limb. Although mainly cytoplasmic, also some nuclear labeling is detected in immunoreactive cells of different tissues, especially in the spinal cord, suggesting the activation of nuclear transcriptional process. The protein is present in tissues with high proliferative activity, but is low to absent in most blastema cells and connective tissues during regeneration. The study indicates that the presence of MARCKS-like protein is a general reaction that favors regeneration in amphibians and possibly also in other vertebrates.