Publications by authors named "Bernard Degnan"

The eyes of squids, octopuses, and cuttlefish are a textbook example for evolutionary convergence, due to their striking similarity to those of vertebrates. For this reason, studies on cephalopod photoreception and vision are of importance for a broader audience. Previous studies showed that genes such as pax6, or certain opsin-encoding genes, are evolutionarily highly conserved and play similar roles during ontogenesis in remotely related bilaterians.

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Animals are influenced by the season, yet we know little about the changes that occur in most species throughout the year. This is particularly true in tropical marine animals that experience relatively small annual temperature and daylight changes. Like many coral reef inhabitants, the crown-of-thorns starfish (COTS), well known as a notorious consumer of corals and destroyer of coral reefs, reproduces exclusively in the summer.

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Objectives: Adolescents with type 1 diabetes (T1D) and their caregivers endorse high diabetes distress (DD). Limited studies have documented the impact of DD on Black youth. The aims of the present study were to (1) describe DD among a sample of Black adolescents with T1D and their caregivers, (2) compare their DD levels with published normative samples, and (3) determine how DD relates to glycemic outcomes, diabetes self-management, parental monitoring of diabetes, and youth depressive symptoms.

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Interkingdom signalling within a holobiont allows host and symbionts to communicate and to regulate each other's physiological and developmental states. Here we show that a suite of signalling molecules that function as neurotransmitters and neuromodulators in most animals with nervous systems, specifically dopamine and trace amines, are produced exclusively by the bacterial symbionts of the demosponge . Although sponges do not possess a nervous system, expresses rhodopsin class G-protein-coupled receptors that are structurally similar to dopamine and trace amine receptors.

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People living with HIV (PLHIV) are at a higher risk of having cerebrocardiovascular diseases (CVD) compared to HIV negative (HIV) individuals. The mechanisms underlying this elevated risk remains elusive. We hypothesize that HIV infection results in modified microRNA (miR) content in plasma extracellular vesicles (EVs), which modulates the functionality of vascular repairing cells, i.

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Marine larvae have factored heavily in pursuits to understand the origin and evolution of animal life cycles. Recent comparisons of gene expression and chromatin state in different species of sea urchin and annelid show how evolutionary changes in embryonic gene regulation can lead to markedly different larval forms.

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Marine animals in the wild are often difficult to access, so they are studied in captivity. However, the implicit assumption that physiological processes of animals in artificial environments are not different from those in the wild has rarely been tested. Here, we investigate the extent to which an animal is impacted by captivity by comparing global gene expression in wild and captive crown-of-thorns starfish (COTS).

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Background: Many echinoderms form seasonal aggregations prior to spawning. In some fecund species, a spawning event can lead to population outbreaks with detrimental ecosystem impacts. For instance, outbreaks of crown-of-thorns starfish (COTS), a corallivore, can destroy coral reefs.

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Article Synopsis
  • Transcription factors from the Forkhead (Fox) gene family play essential roles in animal development, immunity, and physiology.
  • Most Fox genes evolved after the split between animals and choanoflagellates, but some are ancient.
  • In the marine sponge Amphimedon queenslandica, 17 Fox genes were identified, with eight showing rapid expression changes during development, indicating a conserved role in developmental processes across metazoans.
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Investigations of host-symbiont interactions can benefit enormously from a complete and reliable holobiont gene expression profiling. The most efficient way to acquire holobiont transcriptomes is to perform RNA-Seq on both host and symbionts simultaneously. However, optimal methods for capturing both host and symbiont mRNAs are still under development, particularly when the host is a eukaryote and the symbionts are bacteria or archaea.

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Most organisms respond to light. Here, we investigate the origin of metazoan phototransduction by comparing well-characterized opsin-based photosystems in neural animals with those in the sponge . Although sponges lack neurons and opsins, they can respond rapidly to light.

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The chromatin environment plays a central role in regulating developmental gene expression in metazoans. Yet, the ancestral regulatory landscape of metazoan embryogenesis is unknown. Here, we generate chromatin accessibility profiles for six embryonic, plus larval and adult stages in the sponge These profiles are reproducible within stages, reflect histone modifications, and identify transcription factor (TF) binding sequence motifs predictive of -regulatory elements operating during embryogenesis in other metazoans, but not the unicellular relative Motif analysis of chromatin accessibility profiles across embryogenesis identifies three major developmental periods.

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Pearls are highly prized biomineralized gemstones produced by molluscs. The appearance and mineralogy of cultured pearls can vary markedly, greatly affecting their commercial value. To begin to understand the role of pearl sacs-organs that form in host oysters from explanted mantle tissues that surround and synthesize pearls-we undertook transcriptomic analyses to identify genes that are differentially expressed in sacs producing pearls with different surface and structural characteristics.

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Molluscs biomineralize structures that vary in composition, form, and function, prompting questions about the genetic mechanisms responsible for their production and the evolution of these mechanisms. Chitons (Mollusca, Polyplacophora) are a promising system for studies of biomineralization because they build a range of calcified structures including shell plates and spine- or scale-like sclerites. Chitons also harden the calcified teeth of their rasp-like radula with a coat of iron (as magnetite).

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Article Synopsis
  • Enhancers are DNA regulatory sequences that help define cell identity during development in animals, while transcription factors (TFs) interact with these enhancers.
  • Researchers used enhancers from an evolutionarily distant marine sponge to manipulate zebrafish and mouse development, revealing shared TF binding patterns.
  • The study suggests a highly conserved and adaptable genomic regulatory system that has been utilized across different species to form specific gene regulatory networks.
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To better understand the origin of animal cell types, body plans, and other morphological features, further biological knowledge and understanding are needed from non-bilaterian phyla, namely, Placozoa, Ctenophora, and Porifera. This chapter describes recent cell staining approaches that have been developed in three phylogenetically distinct sponge species-the homoscleromorph Oscarella lobularis, and the demosponges Amphimedon queenslandica and Lycopodina hypogea-to enable analyses of cell death, proliferation, and migration. These methods allow for a more detailed understanding of cellular behaviors and fates, and morphogenetic processes in poriferans, building on current knowledge of sponge cell biology that relies chiefly on classical (static) histological observations.

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Article Synopsis
  • The synapse is a critical part of neuron functioning that evolved from smaller protein submodules, which may also play roles in non-neural creatures like sponges.
  • Researchers identified genes in the sponge Amphimedon queenslandica that correspond to these synaptic submodules in neural animals and studied their expression patterns.
  • While certain synaptic genes are co-expressed in sponge cells related to sensing and feeding, this does not indicate the presence of functional synapses in sponges, suggesting they had alternative methods for sensory input before true synapses evolved.
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  • Vertebrates have highly methylated genomes at CpG sites, while invertebrates generally have less methylation, marking an evolutionary milestone in vertebrate genome regulation.
  • A study found that sponges, which may be closely related to early animal ancestors, also possess highly methylated genomes despite differing in size and structure.
  • The research reveals shared characteristics in DNA methylation patterns between vertebrates and sponges, suggesting that complex regulatory systems may trace back to early animal evolution, challenging the notion that hypermethylation is unique to vertebrates.
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A widely held-but rarely tested-hypothesis for the origin of animals is that they evolved from a unicellular ancestor, with an apical cilium surrounded by a microvillar collar, that structurally resembled modern sponge choanocytes and choanoflagellates. Here we test this view of animal origins by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types-choanocytes, pluripotent mesenchymal archaeocytes and epithelial pinacocytes-with choanoflagellates and other unicellular holozoans. Unexpectedly, we find that the transcriptome of sponge choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or sponges alone.

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Background: Animals have a greater diversity of signalling pathways than their unicellular relatives, consistent with the evolution and expansion of these pathways occurring in parallel with the origin of animal multicellularity. However, the genomes of sponges and ctenophores - non-bilaterian basal animals - typically encode no, or far fewer, recognisable signalling ligands compared to bilaterians and cnidarians. For instance, the largest subclass of receptor tyrosine kinases (RTKs) in bilaterians, the Eph receptors (Ephs), are present in sponges and ctenophores, but their cognate ligands, the ephrins, have not yet been detected.

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Background: Ependymins were originally defined as fish-specific secreted glycoproteins involved in central nervous system plasticity and memory formation. Subsequent research revealed that these proteins represent a fish-specific lineage of a larger ependymin-related protein family (EPDRs). EPDRs have now been identified in a number of bilaterian animals and have been implicated in diverse non-neural functions.

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Background: Micro RNAs (miRNAs) and piwi interacting RNAs (piRNAs), along with the more ancient eukaryotic endogenous small interfering RNAs (endo-siRNAs) constitute the principal components of the RNA interference (RNAi) repertoire of most animals. RNAi in non-bilaterians - sponges, ctenophores, placozoans and cnidarians - appears to be more diverse than that of bilaterians, and includes structurally variable miRNAs in sponges, an enormous number of piRNAs in cnidarians and the absence of miRNAs in ctenophores and placozoans.

Results: Here we identify thousands of endo-siRNAs and piRNAs from the sponge Amphimedon queenslandica, the ctenophore Mnemiopsis leidyi and the cnidarian Nematostella vectensis using a computational approach that clusters mapped small RNA sequences and annotates each cluster based on the read length and relative abundance of the constituent reads.

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A hallmark of metazoan evolution is the emergence of genomic mechanisms that implement cell-type-specific functions. However, the evolution of metazoan cell types and their underlying gene regulatory programmes remains largely uncharacterized. Here, we use whole-organism single-cell RNA sequencing to map cell-type-specific transcription in Porifera (sponges), Ctenophora (comb jellies) and Placozoa species.

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Although developmental regulation by long non-coding RNAs (lncRNAs) appears to be a widespread feature amongst animals, the origin and level of evolutionary conservation of this mode of regulation remain unclear. We have previously demonstrated that the sponge -a morphologically-simple animal-developmentally expresses an array of lncRNAs in manner akin to more complex bilaterians (insects + vertebrates). Here, we first show that lncRNAs are expressed in specific cell types in larvae, juveniles and adults.

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