Project description:Feather evolution enabled feathered dinosaurs and early Mesozoic birds to venture into new ecological niches. Studying how feathers and scales are specified provides insight into how a new organ evolves. We use genome-wide analyses to identify feather-associated genes and test their feather-forming ability by expressing them in chicken and alligator scales. Intermediate morphotypes revealed five cardinal morphogenetic events: localized growth zone, follicle invagination, branching, feather keratin differentiation and dermal papilla formation. In contrast to molecules known to induce feathers on scales (retinoic acid, beta-catenin), we identify novel scale-feather converters (Sox2, Zic1, Grem1, Spry2, Sox18) which induce only one or several of the five regulatory modules. Some morphotypes resemble filamentous appendages found in feathered dinosaur fossils, while others demonstrate some characteristics of modern feathers. We propose that at least five morpho-regulatory modules were used to diversify ancient reptile scales. The regulatory combination and hierarchical integration led to extant feather forms.
Project description:Feather evolution enabled feathered dinosaurs and early Mesozoic birds to venture into new ecological niches. Studying how feathers and scales are specified provides insight into how a new organ evolves. We use genome-wide analyses to identify feather-associated genes and test their feather-forming ability by expressing them in chicken and alligator scales. Intermediate morphotypes revealed five cardinal morphogenetic events: localized growth zone, follicle invagination, branching, feather keratin differentiation and dermal papilla formation. In contrast to molecules known to induce feathers on scales (retinoic acid, beta-catenin), we identify novel scale-feather converters (Sox2, Zic1, Grem1, Spry2, Sox18) which induce only one or several of the five regulatory modules. Some morphotypes resemble filamentous appendages found in feathered dinosaur fossils, while others demonstrate some characteristics of modern feathers. We propose that at least five morpho-regulatory modules were used to diversify ancient reptile scales. The regulatory combination and hierarchical integration led to extant feather forms.
Project description:Feather evolution enabled feathered dinosaurs and early Mesozoic birds to venture into new ecological niches. Studying how feathers and scales are specified provides insight into how a new organ evolves. We use genome-wide analyses to identify feather-associated genes and test their feather-forming ability by expressing them in chicken and alligator scales. Intermediate morphotypes revealed five cardinal morphogenetic events: localized growth zone, follicle invagination, branching, feather keratin differentiation and dermal papilla formation. In contrast to molecules known to induce feathers on scales (retinoic acid, beta-catenin), we identify novel scale-feather converters (Sox2, Zic1, Grem1, Spry2, Sox18) which induce only one or several of the five regulatory modules. Some morphotypes resemble filamentous appendages found in feathered dinosaur fossils, while others demonstrate some characteristics of modern feathers. We propose that at least five morpho-regulatory modules were used to diversify ancient reptile scales. The regulatory combination and hierarchical integration led to extant feather forms.
Project description:Birds and other reptiles possess a diversity of feather and scale-like skin appendages. Feathers are commonly assumed to have originated from ancestral scales in theropod dinosaurs. However, most birds also have scaled feet, indicating birds evolved the capacity to grow both ancestral and derived morphologies. This suggests a more complex evolutionary history than a simple linear transition between feathers and scales. We set out to investigate the evolution of feathers via the comparison of transcriptomes assembled from diverse skin appendages in chicken, emu, and alligator. Our data reveal that feathers and the overlapping ‘scutate’ scales of birds share more similar gene expression to each other, and to two types of alligator scales, than they do to the tuberculate ‘reticulate’ scales on bird footpads. Accordingly, we propose a history of skin appendage diversification, in which feathers and bird scutate scales arose from ancestral archosaur body scales, whereas reticulate scales arose earlier in tetrapod evolution. We also show that many “feather-specific genes” are also expressed in alligator scales. In-situ hybridization results in feather buds suggest that these genes represent ancestral scale genes that acquired novel roles in feather morphogenesis and were repressed in bird scales. Our findings suggest that the differential reuse, in feathers, and suppression, in bird scales, of genes ancestrally expressed in archosaur scales has been a key factor in the origin of feathers – and may represent an important mechanism for the origin of evolutionary novelties.
Project description:Epithelial appendages are the product of epithelial – mesenchymal interactions. Tissue recombination experiments showed that in general, the dermis determines the phenotype of the epithelial appendage. Chicken dorsal skin epithelium interacts with its underlying mesenchyme to form feathers beginning at E7 (H&H stage 31), while metatarsal scale epithelium interacts with its mesenchyme to form scales beginning at E9 (H&H stage 35) which stabilize around E12 (H&H stage 38). We sought to evaluate the molecular differences of tissues with different competence and inductive abilities to form feathers and scales.
Project description:Epithelial appendages are the product of epithelial – mesenchymal interactions. Tissue recombination experiments showed that in general, the dermis determines the phenotype of the epithelial appendage. Chicken dorsal skin epithelium interacts with its underlying mesenchyme to form feathers beginning at E7 (H&H stage 31), while metatarsal scale epithelium interacts with its mesenchyme to form scales beginning at E9 (H&H stage 35) which stabilize around E12 (H&H stage 38). We sought to evaluate the molecular differences of tissues with different competence and inductive abilities to form feathers and scales. Chicken embryos were selected to obtain competent E7 and non-competent at E9 feather forming skin from dorsal. The competent E9 and non-competent E11 meta-tarsal scale forming skin from metatarsal were selected for examing the differences in regional specificity. Epithelium and mesenchyme from each skin were prepared separately. Samples were prepared for RNA extraction and hybridization on Affymetrix microarrays. We gathered 8 sets of samples for the analysis: undifferentiated E7 feather skin epithelium (E7fe) and mesenchyme (E7fm); differentiated E9 feather skin epithelium (E9fe) and mesenchyme (E9fm); undifferentiated E9 scale skin epithelium (E9se) and mesenchyme (E9sm); and differentiated E11 scale skin epithelium (E11se) and mesenchyme (E11sm)
Project description:Fish scales are an important reservoir of calcium and phosphorus and together with the skin function as an integrated barrier against environmental changes and external aggressors. Histological studies have revealed that the skin and scales regenerate rapidly in fish when they are lost or damaged. In the present manuscript the histological and molecular changes underlying skin and scale regeneration in fed and fasted sea bream (Sparus auratus) were studied using a microarray 3 and 7 days after scale removal to provide a comprehensive molecular understanding of the early stages of these processes. Histological analysis of skin/scales revealed 3 days after scale removal re-epithelisation had occurred and the scale pocket had formed. In animals with scales removed, there was significant up-regulation of genes involved in cell cycle regulation, cell proliferation and adhesion, immune response and antioxidant activities. The expression profiles of the fasted animals centred on maintaining energy homeostasis. The utilisation of fasting as a treatment emphasised the competing whole animal physiological requirements with regard to barrier repair, infection control and energy homeostasis. Gene expression of sea bream (Sparus auratus) skin and scales was analysed in normal and treated animals. Three different treatments were applied: 1. scales removal at day 0 of the experiment; 2. unfed fish 7 days prior the start of the experiment; and 3. scales removal at day 0 of the experiment of unfed fish 7 days prior the start of the experiment. Fish were sampled at two different days: day 3 and day 7 after scale removal. Five individuals from control and experimental groups were analysed for both sampling days (3 and 7), resulting in a total of 40 samples analysed by microarray.
Project description:Zebrafish (Danio rerio) are a compelling model to study lymphocytes because zebrafish and humans have similar adaptive immune systems, including their lymphocytes. Antibodies that recognize zebrafish proteins are sparse, so many investigators utilize transgenic, lymphocyte-specific fluorophore-labeled lines. Human and zebrafish lymphocyte types are conserved, but many aspects of zebrafish lymphocyte biology remain uninvestigated, including lymphocytes in peripheral tissues, like epidermis. Here, we report the first study focused on zebrafish epidermal lymphocytes, using scales. Obtaining zebrafish blood via non-lethal methods is difficult; scales represent a source to longitudinally sample live fish. We developed a novel biopsy technique, collecting scales to analyze epithelial lymphocytes from several fluorescently-labeled lines. We imaged scales via confocal microscopy and demonstrated multiple lymphocyte types in scales/epidermis, quantifying them flow cytometrically. We profiled gene expression of scale, thymic, and marrow lymphocytes from the same animals, revealing B- and T-lineage signatures. Single-cell qRT-PCR and RNA sequencing (scRNA-seq) show not only canonical B and T cells, but also novel lymphocyte populations not described previously. To validate longitudinal scale biopsies, we serially sampled scales from fish treated with dexamethasone (DXM), demonstrating epidermal lymphocyte responses. To analyze cells functionally, we employed a bead-ingestion assay, showing thymic, marrow, and epidermal lymphocytes have phagocytic activity. In summary, we establish a novel, non-lethal technique to obtain zebrafish lymphocytes, providing the first quantification, expression profiling, and functional data (DXM responses and phagocytosis) from epidermal lymphocytes in the zebrafish model.
Project description:The zebrafish scale is a thin membranous bone embedded in the skin and consists of osteoblasts, osteoclasts, and bone matrix, providing an elegant model to understand bone metabolisms. we developed an in vivo model system using zebrafish scales to investigate the effect of extremely low-frequency-electromagnetic fields (ELF-EMFs) on fracture healing. In this study, we have performed RNA-seq analysis on intact scales, fractured scales not exposed to ELF-EMFs, and fractured scales exposed to 10 militesra (mT) of ELF-EMFs.