Project description:Our genomic, bulk and single-cell transcriptomic, functional, and developmental characterization of the Terrazzo corn snake color morph and the extensive comparison with wild-type snakes puts forward the dual role of PMEL in snake skin coloration, both in the differentiation of chromatophores during embryogenesis and the melanogenesis in melanophores.
Project description:Our genomic, bulk and single-cell transcriptomic, functional, and developmental characterization of the Terrazzo corn snake color morph and the extensive comparison with wild-type snakes puts forward the dual role of PMEL in snake skin coloration, both in the differentiation of chromatophores during embryogenesis and the melanogenesis in melanophores.
Project description:Snakebite, classified by World Health Organization (WHO) as a neglected tropical disease, causes more than 100,000 deaths and 400,000 injuries per year. Currently, available antivenoms do not bind with strong specificity to target toxins, which means that severe complications can still occur despite treatment. Moreover, the cost of antivenom is expensive. Knowledge of venom compositions is fundamental for producing a specific antivenom that has high effectiveness, low side effects, and ease of manufacture. With advances in mass spectrometry techniques, venom proteomes can now be analyzed in great depth at high efficiency. However, these techniques require genomic and transcriptomic data for interpreting mass spectrometry data. This study aims to establish and incorporate genomics, transcriptomics, and proteomics data to study venomics of Thai venomous snake, Daboia siamensis. More than a hundred proteins that have not been reported as venom components of this snake such as hyaluronidase-1 and Phospholipase B were discovered. The use of conventional reference databases for mass spectrometry analysis can detect only 46% of proteins identified by integrated omics data. Thus, this multi-omics data is necessary for venomics studies. These findings will be valuable not only for antivenom production but also for the development of novel therapeutics.
Project description:While the vertebrate body plan is highly conserved amongst all species of this taxon, extreme variations thereof can be documented in snakes, which display both an absence of limbs and an unusually elongated trunk. As Hox genes are strong candidates both for the making and the evolution of this body plan, their comparative study in such a morphologically diverged group is informative regarding their potential causative importance in these processes. In this work we use an interspecies comparative approach where different aspects of regulation at the HoxD locus are investigated. We find that although spatial collinearity and associated epigenetic mark dynamics are conserved in the corn snake, other regulatory modalities have been largely restructured. A BAC transgenic approach indeed revealed that, while the majority of mesodermal enhancers in vertebrates appear to be mostly located outside of the cluster, the corn snake contains most mesodermal trunk enhancers within the HoxD cluster. We also find that, despite the absence of limbs and an altered Hoxd gene regulation in external genitalia, the bimodal chromatin structure at the corn snake HoxD locus is maintained. The analysis of particular enhancer sequences initially defined in the mouse and further isolated at the snake orthologous locus showed differences in their specificities for the limb and genital bud expression. Of particular interest, a snake counterpart of a mouse limb-only enhancer sequence evolved into a genital-only enhancer. Such a regulatory exaptation suggests that enhancer versatility may have been an important factor to accompany the transition towards the snake body plan. These results show that vertebrate morphological evolution is likely to have been associated with extensive reorganization at the HoxD regulatory landscapes while respecting a very conserved general regulatory framework.
Project description:We used gene expression accompanied by physical characteristics and gill Na+/K+-ATPase activity to analyze physiological differences associated with two life history variations of juvenile fall Chinook Salmon in the Snake River basin. Subyearlings originating in the Snake River typically migrate seaward as subyearlings, whereas many subyearlings from the Clearwater River delay seaward migration during summer and complete seaward migration the following spring as yearlings. We examined gill Na+/K+-ATPase activity and gene expression of subyearlings at different times during rearing and seaward emigration. Natural-origin Snake River subyearlings rearing under an increasing photoperiod and seasonally increasing temperatures showed a typical increasing pattern of parr to smolt gill Na+/K+-ATPase activity development, which then declined into autumn. In contrast, Clearwater River subyearlings that had experienced cooler temperatures showed no pattern of increasing gill Na+/K+-ATPase activities and were not different from parr. Liver transcription of genes involved in DNA repair and binding, the cell cycle, metabolism (steroid, fatty acid and other metabolic pathways) iron homeostasis, heme and oxygen binding, the immune response, and male sexual development were enriched amongst genes differentially expressed between Snake River parr versus smolts. Gene expression results confirmed that Clearwater River subyearlings were parr-like in their physiological status. By autumn, subyearlings had low gill Na+/K+-ATPase activities despite their large size and external smolt characteristics. We suggest that environmental factors like temperature and photoperiod influence subyearling physiological status in each river that ultimately dictates juvenile life history pathways. Non-migrating and migrating natural subyearling fall Chinook salmon were collected from the Snake River. Non-migrating natural subyearling fall Chinook salmon were collected from the Clearwater River. Twelve fish were collected at each of four different time points for a total of 48 fish. Total RNA was extracted from the liver of each fish. Equal amounts of RNA from three fish were pooled to create four pools of RNA per time point. Each RNA pool was hybridized to an array for a total of 16 arrays with four arrays per time point.
Project description:Venomous animals have traditionally been studied from a proteomic (but also transcriptomic) perspective, often overlooking the study of venom from a genomic point of view until recently. The rise of genomics has led to an increase in the number of reference genomes for non-model organisms, including venomous taxa, enabling new questions on venom evolution from a genomic context. Although venomous snakes are the fundamental model system in venom research, the number of high-quality reference genomes in the group remains limited. In this study, we present a high-quality chromosome-level reference genome for the Arabian horned viper (Cerastes gasperettii), a highly venomous snake native to the Arabian Peninsula. Our highly-contiguous genome allowed us to explore macrochromosomal rearrangements within the Viperidae family, as well as across squamate reptile evolution. Furthermore, we identified a total of ten different toxins conforming the venom’s core, in line with our proteomic results. We also compared microsyntenic changes in the main toxin gene clusters with those of other venomous snake species, highlighting the pivotal role of gene duplication and loss in the emergence and diversification of the two main toxin families for Cerastes gasperettii. Using Illumina data, we reconstructed the demographic history and genome-wide diversity of the species, revealing how historical aridity likely drove population expansions. Finally, this study highlights the importance of using long-read sequencing as well as chromosome-level reference genomes to disentangle the origin and diversification of toxin families in venomous species.