Project description:The genetic and developmental mechanisms that control the decision between scale and feather growth â two profoundly different epidermal appendages, and an important developmental shift in the evolution of birds from their dinosaurian ancestors â remain poorly understood. Domestic pigeons display dramatic variation in foot epidermal appendages within a single species, and classical studies suggest that a small number of genes control much of this variation; thus pigeons provide a tractable model to understand skin appendage specification and variation. Here we show that feathered feet in pigeons are the consequence of a partial transformation of limb-type identity mediated by cis-regulatory changes in the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also demonstrate that ectopic hindlimb expression of Tbx5 is associated with the development of foot feathers in domestic chickens, suggesting that similar developmental mechanisms underlie phenotypic convergence in avian lineages that diverged over 100 MYA. These results show how qualitative and quantitative changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide a viable molecular mechanism for the evolution of hindlimb scale and feather distribution in dromaeosaurs. Examination of H3K27ac status in embryonic limb buds from two domestic pigeon breeds, racing homer and Indian fantail
Project description:MITF, a gene that is mutated in familial melanoma and Waardenburg syndrome, encodes multiple isoforms expressed from alternative promoters that share common coding exons but have unique amino termini. It is not completely understood how these isoforms influence pigmentation in different tissues and how expression of these independent isoforms of MITF are regulated. Here, we show that melanocytes express two isoforms of MITF, MITF-A and MITF-M. Expression of MITF-A is partially regulated by a newly identified retinoid enhancer element located upstream of the MITF-A promoter. Mitf-A knockout mice have only subtle changes in melanin accumulation in the hair and reduced Tyr expression in the eye. In contrast, Mitf-M null mice have enlarged kidneys, lack neural crest derived melanocytes in the skin, choroid, and iris stroma; yet maintain pigmentation within the retinal pigment epithelium and iris pigment epithelium of the eye. Taken together, these studies identify a critical role for MITF-M in melanocytes, a minor role for MITF-A in regulating pigmentation in the hair and Tyr expression in the eye, and a novel role for MITF-M in size control of the kidney.
Project description:In feather-footed pigeons, mutant alleles of PITX1 and TBX5 drive the partial redeployment of an evolutionarily conserved forelimb genetic program in the hindlimb.
Project description:Transcriptome sequencing of non-model organisms is valuable resource of the genetic basis of ecological-meaningful traits. The Royal Irises, Iris section Oncocyclus (Iris: Iridaceae, order Asparagales), are a Middle-East group of species in the course of speciation. The species are characterized with extremely large flowers, a huge range of flower colors and a unique pollination system. The Royal Irises, which are a symbol of conservation in the Middle-east, serve as a model for evolutionary processes of speciation and plant ecology. However, there are not sufficient transcriptomic and genomic data for molecular characterization. Thus, it is necessary to generate massive transcript sequences for functional characterization and molecular marker development for the Royal Irises. The Iris transcriptome sequencing provides valuable resource for studying adaptation-associated traits in this non-model plant. Although intensive eco-evolutionary studies, this is the first reported transcriptome for the Royal Irises. The data available from this study will facilitate gene discovery, functional genomic studies and development of molecular markers in irises, and will provide genetic tools for their conservation.
Project description:Butterfly wing patterns are an important model for studying the genetic basis of morphological evolution. Here we used RNA-seq expression profiling in the butterfly Vanessa cardui to characterize the transcriptional basis of wing pigmentation. This approach identified numerous candidate genes including known and suspected components of the insect melanin and ommochrome biosynthetic pathways.
Project description:The human iris tissue is a thin, circular structure in the eye and it is made up of a pigmented epithelial structure. It is a protected internal organ of the eye, located behind the cornea and the aqueous humour. Iris serves main function to control the diameter, size of the pupil and regulation of light exposure to the internal eye structures. Damage or absent iris always results in allowing excess amount of light into the eye which causes medical problem for the patient and also a psychological problem due to strange eye with black hole. A damaged or congenitally defective iris does not function well which results in poor quality of vision. Although different efforts have been made to elucidate the different parts of the human eye proteome in depth, the protein composition of the human iris tissue remains largely unexplored. We have performed a comprehensive analysis of the human iris tissue employing protein and peptide fractionation methods followed by LC-MS/MS identifying 4918 proteins. Bioinformatics analysis revealed that protein components of the iris tissue participated in a plethora of biological process highlighting cell signal transduction, communication, metabolism, energy pathways protein metabolism cell growth and maintenance, transport and immune response activities. We also compared the proteins of iris tissue with high throughput studies on other parts of eye and plasma proteome, which resulted in identifying proteins unique to iris. To our knowledge, this study is the first attempt to profile the global proteome of the human iris tissue. Taken together, these results increase our knowledge about the molecular composition of the human iris tissue and may be useful to understand the molecular basis of the iris and the baseline proteome described in this study should serve as a resource for future research in iris tissue
Project description:The genetic and developmental mechanisms that control the decision between scale and feather growth – two profoundly different epidermal appendages, and an important developmental shift in the evolution of birds from their dinosaurian ancestors – remain poorly understood. Domestic pigeons display dramatic variation in foot epidermal appendages within a single species, and classical studies suggest that a small number of genes control much of this variation; thus pigeons provide a tractable model to understand skin appendage specification and variation. Here we show that feathered feet in pigeons are the consequence of a partial transformation of limb-type identity mediated by cis-regulatory changes in the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also demonstrate that ectopic hindlimb expression of Tbx5 is associated with the development of foot feathers in domestic chickens, suggesting that similar developmental mechanisms underlie phenotypic convergence in avian lineages that diverged over 100 MYA. These results show how qualitative and quantitative changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide a viable molecular mechanism for the evolution of hindlimb scale and feather distribution in dromaeosaurs.
Project description:Skin color is highly variable in Africans, yet little is known about the underlying molecular mechanism. We identified 1,157 candidate variants influencing skin pigmentation in indigenous Africans by genome-wide association studies and scans of natural selection based on differentiation in allele frequencies between lightly pigmented southern African Khoesan populations and other darkly pigmented African populations. We applied massively parallel reporter and chromosome conformation capture assays to identify novel regulatory variants and their target genes related to skin pigmentation in melanocytic cells. We identified 165 SNPs showing strong differential regulatory activities between alleles. Combining CRISPR-mediated genome editing, transcriptome profiling and melanin assays, we identified causal regulatory variants impacting pigmentation near MFSD12/HMG20B, MITF, OCA2, and DDB1/CYB561A3/TMEM138. We identified CYB561A3 as a novel gene regulating pigmentation by impacting genes involved in oxidative phosphorylation and melanogenesis. Our results broaden our understanding of the genetic basis of human skin color diversity and human adaptation. To test the role of candidate enhancers and variants in skin pigmentation, we performed CRISPR inhibition or knockout of enhancers containing the functional variants identified by MPRA in melanocytic cells. Then, we performed gene expression profiling analysis using data obtained from RNA-seq of these CRISPR-edited cells. We also performed RNA-seq using CYB561A3-koncout MNT1 cells or CYB561A3-overexpressing MNT1 cells