Project description:The morphologies of the amniote phallus and limbs differ dramatically, but these structures share signaling pathways and patterns of gene expression in early development. Thus far, the extent to which genital and limb transcriptional networks share cis-regulatory elements has remained unexplored. Using chromatin immunoprecipitation with an antibody against the histone modification mark H3K27ac followed by Illumina high-throughput sequencing, we identify thousands of active enhancers in developing limbs, genital tubercle, and additional embryonic tissues of the mouse and green anole lizard (Anolis carolinensis). We show in global analyses of cis-regulatory activity that embryonic limbs and genitalia display overlapping patterns of enhancer activity, and that many H3K27ac-marked regions are shared between mouse and green anole. Our findings support the hypothesis that the amniote phallus evolved through co-option of a preexisting appendage developmental program.
Project description:This experiment contains the Anolis carolinensis subset of data from the experiment E-GEOD-41338 (http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-41338/). mRNA profiles of several organs (brain, liver, kidney, heart, skeletal muscle) in multiple vertebrate species (mouse, chicken, lizard, frog, pufferfish) were generated by deep sequencing using Illumina HiSeq to better understand how species with similar repertoires of protein-coding genes differ so markedly at the phenotypic level.
Project description:Lizards cannot naturally regenerate limbs but are the closest known relatives of mammals capable of epimorphic tail regrowth. However, the mechanisms regulating lizard blastema derivation and chondrogenesis remain unclear. We utilized single-cell RNA sequencing analyses of regenerating lizard tails throughout the course of regeneration to assess diversity and heterogeneity in regeneating tail cell populations.
Project description:Lung function is closely coupled to its structural anatomy, which varies greatly across vertebrates. Although architecturally simple, a complex pattern of airflow is thought to be achieved in the lizard lung due to its cavernous central lumen and honeycomb-shaped wall. We find that the wall of the lizard lung is generated from an initially smooth epithelial sheet, which is pushed through holes in a hexagonal smooth muscle meshwork by forces from fluid pressure, similar to a stress ball. By combining next-generation sequencing with timelapse imaging, we reveal that the hexagonal smooth muscle geometry self-assembles in response to circumferential and axial stresses downstream of pressure. A quantitative computational model predicts the pressure-driven changes in epithelial topology, which we replicate using a 3D-printed engineered tissue model of optogenetically-driven smooth muscle contraction. These results reveal the physical principles used to sculpt the unusual architecture of the lizard lung, which could be exploited as a novel strategy to engineer tissues.
Project description:How species with similar repertoires of protein coding genes differ so dramatically at the phenotypic level is poorly understood. From comparing the transcriptomes of multiple organs from vertebrate species spanning ~350 million years of evolution, we observe significant differences in alternative splicing complexity between the main vertebrate lineages, with the highest complexity in the primate lineage. Moreover, within as little as six million years, the splicing profiles of physiologically-equivalent organs have diverged to the extent that they are more strongly related to the identity of a species than they are to organ type. Most vertebrate species-specific splicing patterns are governed by the highly variable use of a largely conserved cis-regulatory code. However, a smaller number of pronounced species-dependent splicing changes are predicted to remodel interactions involving factors acting at multiple steps in gene regulation. These events are expected to further contribute to the dramatic diversification of alternative splicing as well as to other gene regulatory changes that contribute to phenotypic differences among vertebrate species. mRNA profiles of several organs (brain, liver, kidney, heart, skeletal muscle) in multiple vertebrate species (mouse, chicken, lizard, frog, pufferfish) generated by deep sequencing using Illumina HiSeq
Project description:Comparative RNA-seq profiling of mouse and anole lizard developing limbs and external genitalia, to assess evolutionary and develomental relationships, between the two tissue types based on transcriptomic data RNA-seq profiling of embryonic limb and external genitalia tissue at different stages of development, in mouse and anole lizard, in duplicates, using Illumina HiSeq
Project description:The amniote pallium, a vital component of the forebrain, has undergone considerable evolutionary divergence across species and is critical for a variety of functions including sensation, memory and learning. The relationship between pallial subregions in different species remain elusive, particularly regarding the identification of homologous neurons and their similar or distinct signatures. Here, we utilized single-nucleus RNA sequencing to examine over 130,000 nuclei from macaque (Macaca fascicularis) neocortex, alongside datasets from human (Homo sapiens), mouse (Mus musculus), zebra finch(Taeniopygia guttata), turtle (Chrysemys picta bellii), and lizard (Pogona vitticeps), for a cross-species comparison.
Project description:The relationship between gene network structure and expression variation among individuals and species: Variation among individuals is a prerequisite of evolution by natural selection. As such, identifying the origins of variation is a fundamental goal of biology. We investigated the link between gene interactions and variation in gene expression among individuals and species, using the mammalian limb as a model system. We first built interaction networks for key genes regulating early (outgrowth; E9.5-11) and late (expansion and elongation; E11-13) limb development in mouse. This resulted in an Early (ESN) and Late (LSN) Stage Network. Computational perturbations of these networks suggest that the ESN is more robust. We then quantified levels of the same key genes among mouse individuals, and found that they vary less at earlier limb stages and that variation in gene expression is heritable. Finally, we quantified variation in gene expression levels among four mammals with divergent limbs (bat, opossum, mouse and pig), and found that levels vary less among species at earlier limb stages. We also found that variation in gene expression levels among individuals and species are correlated for earlier and later limb development. In conclusion, results are consistent with the robustness of the ESN buffering among-individual variation in gene expression levels early in mammalian limb development, and constraining the evolution of early limb development among mammalian species. Transcriptomic insights into the genetic basis of mammalian limb diversity: From bat wings to whale flippers, limb diversification has been crucial to the evolutionary success of mammals. We performed the first transcriptome-wide study of limb development in multiple species to explore the hypothesis that mammalian limb diversification has proceeded through the differential expression of conserved shared genes, rather than by major changes to limb patterning. Specifically, we investigated the manner in which the expression of shared genes has evolved within and among mammalian species. We assembled and compared transcriptomes of bat, mouse, opossum, and pig fore- and hind limbs at the ridge, bud, and paddle stages of development. Results suggest that gene expression patterns exhibit larger variation among species during later than earlier stages of limb development, while within species results are more mixed. Consistent with the former, results also suggest that genes expressed at later developmental stages tend to have a younger evolutionary age than genes expressed at earlier stages. A suite of key limb-patterning genes was identified as being differentially expressed among the homologous limbs of all species. However, only a small subset of shared genes is differentially expressed in the fore- and hind limbs of all examined species. Similarly, a small subset of shared genes is differentially expressed within the fore- and hind limb of a single species and among the forelimbs of different species. Taken together, results of this study do not support the existence of a phylotypic period of limb development ending at chondrogenesis, but do support the hypothesis that the hierarchical nature of development translates into increasing variation among species as development progresses.
Project description:Based on its phylogenetic relationship to monitor lizards (Varanidae), Gila monsters (Heloderma spp.), and the earless monitor Lanthanotus borneesis, the Chinese crocodile lizard, Shinisaurus crocodilurus, has been assigned to the Toxicofera clade, which comprises venomous reptiles. However, no data about composition and biological activities of its oral secretion have been reported. In the present study, a proteomic analysis of the mandibular gland of S. crocodilurus and, for comparison, of the herbivorous Solomon Island skink Corucia zebrata, was performed. Scanning electron microscopy (SEM) of the teeth from S. crocodilurus revealed a sharp ridge on the anterior surface, but no grooves, whereas those of C. zebrata possess a flattened crown with a pointed cusp. Proteomic analysis of their gland extracts provided no evidence of venom-derived peptides or proteins, strongly supporting the non-venomous character of these lizards.