Project description:The loss of cone photoreceptor cells, which are critical for optimal daylight vision, have the great impact on vision during retinal degenerations. Retinal differentiation of human induced pluripotent stem cell (hiPSC) sources could provide a renewable source of cone photoreceptors towards developing a cone cell replacement therapy to treat blindness. Demonstration of comparable gene expression profiles between human foetal and stem cell-derived cones at equivalent stages is required to progress the cell transplantation approach into the patient, as it is hypothesised stem cell-derived cones are required to show high levels of developmental recapitulation of the in vivo generated cones. In this study, the AAV2/9.pR2.1.GFP reporter was used to specifically label L/M-opsin cone photoreceptors in human foetal retinal samples, obtained from the MRC-Wellcome Trust Human Developmental Biology Resource, at a range of developmental stages. The L/M-opsin cone population represent the majority cone cell types in the adult human retina and are the only photoreceptors present within the fovea. Using fluorescence activated cell sorting, L/M-opsin GFP+ cones and GFP- retinal populations, alongside total foetal retinal samples containing all retinal cell tytpes, were isolated and processed for bulk RNA sequencing and downstream comparative analysis. Using DESeq2 differential gene expression analyses, statistically significant genes enriched within the GFP+ human foetal LM-opsin cone populations were determined which led to the identification of a cone enriched gene signature of human L/M-opsin cone photoreceptors. The AAV2/9.pR2.1.GFP reporter was applied to hiPSC-derived retinal cultures to isolate and process cone-like cell populations for RNA sequencing using the same strategy developed within the human foetal retina. Applying the cone enriched gene signature to the transcriptome of hiPSC-derived GFP+ samples at equivalent developmental stages revealed some expression similarities in genes found to be enriched within the late foetal L/M-opsin cone photoreceptors. This analysis overall revealed an intermediate stage of cone differentiation was achieved within the hiPSC-derived samples and the comparison to human foetal L/M-opsin gene express profiles suggesting further differentiation of hiPSC-derived sample is required.
Project description:Marine cone snails have attracted researchers from all disciplines but early life stages have received limited attention due to difficulties accessing or rearing juvenile specimens. Here, we document the culture of Conus magus from eggs through metamorphosis to reveal dramatic shifts in predatory feeding behaviour between post-metamorphic juveniles and adult specimens. Adult C. magus capture fish using a set of paralytic venom peptides combined with a hooked radular tooth used to tether envenomed fish. In contrast, early juveniles feed exclusively on polychaete worms using a unique “sting-and-stalk” foraging behaviour facilitated by short, unbarbed radular teeth and a distinct venom repertoire that induces hypoactivity in prey. Our results demonstrate how coordinated morphological, behavioural and molecular changes facilitate the shift from worm- to fish-hunting in C. magus, and showcase juvenile cone snails as a rich and unexplored source of novel venom peptides for ecological, evolutionary and biodiscovery studies.
Project description:The project is aimed at the identification of conotoxins and conopeptides from the venom of marine cone snails found in the Indian coastal waters. Peptides of novel sequences will be further characterized in terms of structural and physico-chemical properties by NMR spectroscopy and other biophysical methods and will be studied for the abilities to elicit pharmacological responses against cellular targets.
Project description:Peptide hormones and neuropeptides form a diverse class of signaling molecules that control essential processes in animals. Despite several breakthroughs in peptide discovery, many signaling peptides remain undiscovered. Recently, we demonstrated the use of somatostatin-like toxins from cone snail venom to identify homologous signaling peptides in prey. Here, we demonstrate that this toxin-based approach can be systematically applied to the discovery of other unknown bilaterian signaling peptides. Using large sequencing datasets, we searched for homologies between cone snail toxins and putative peptides from several important model organisms representing the snails’ prey. We identified and confirmed expression of five toxin families that share strong similarities with previously unknown signaling peptides from mollusks and annelids. One of the peptides was also identified in rotifers, brachiopods, platyhelminths, and arthropods, and another was found to be structurally related to crustacean hyperglycemic hormone, a peptide not previously known to exist in Spiralia. Based on several lines of evidence we propose that these signaling peptides not only exist but serve important physiological functions. Finally, we propose that the discovery pipeline developed here can be more broadly applied to other systems in which one organism has evolved molecules to manipulate the physiology of another.
Project description:Peptide hormones and neuropeptides form a diverse class of signaling molecules that control essential processes in animals. Despite several breakthroughs in peptide discovery, many signaling peptides remain undiscovered. Recently, we demonstrated the use of somatostatin-like toxins from cone snail venom to identify homologous signaling peptides in prey. Here, we demonstrate that this toxin-based approach can be systematically applied to the discovery of other unknown bilaterian signaling peptides. Using large sequencing datasets, we searched for homologies between cone snail toxins and putative peptides from several important model organisms representing the snails’ prey. We identified and confirmed expression of five toxin families that share strong similarities with previously unknown signaling peptides from mollusks and annelids. One of the peptides was also identified in rotifers, brachiopods, platyhelminths, and arthropods, and another was found to be structurally related to crustacean hyperglycemic hormone, a peptide not previously known to exist in Spiralia. Based on several lines of evidence we propose that these signaling peptides not only exist but serve important physiological functions. Finally, we propose that the discovery pipeline developed here can be more broadly applied to other systems in which one organism has evolved molecules to manipulate the physiology of another.
Project description:Peptide hormones and neuropeptides form a diverse class of signaling molecules that control essential processes in animals. Despite several breakthroughs in peptide discovery, many signaling peptides remain undiscovered. Recently, we demonstrated the use of somatostatin-like toxins from cone snail venom to identify homologous signaling peptides in prey. Here, we demonstrate that this toxin-based approach can be systematically applied to the discovery of other unknown bilaterian signaling peptides. Using large sequencing datasets, we searched for homologies between cone snail toxins and putative peptides from several important model organisms representing the snails’ prey. We identified and confirmed expression of five toxin families that share strong similarities with previously unknown signaling peptides from mollusks and annelids. One of the peptides was also identified in rotifers, brachiopods, platyhelminths, and arthropods, and another was found to be structurally related to crustacean hyperglycemic hormone, a peptide not previously known to exist in Spiralia. Based on several lines of evidence we propose that these signaling peptides not only exist but serve important physiological functions. Finally, we propose that the discovery pipeline developed here can be more broadly applied to other systems in which one organism has evolved molecules to manipulate the physiology of another.
Project description:Retinoblastoma is a childhood retinal tumor that initiates in response to biallelic RB1 inactivation. We show that post-mitotic human cone precursors are uniquely sensitive to the oncogenic effects of Rb depletion. Rb knockdown induced cone precursor proliferation in prospectively isolated populations. SNP-array analysis of two Rb/p130-depleted cone precursor cell lines, revealing no megabase-size loss of heterozygosity (LOH) or copy number alterations (CNAs). SNP-array analysis of one Rb/p130-depleted (tumor 1) or one Rb-depleted (tumor 2) cone precursor-derived tumors, revealing no megabase-size LOH or CNAs, consistent with the lack of DNA copy number alterations in some retinoblastomas. Thus, the cone precursor tumors resembled human retinoblastomas at the molecular cytogenetic level.