-
ELife May 2024The circadian clock enables anticipation of the day/night cycle in animals ranging from cnidarians to mammals. Circadian rhythms are generated through a...
The circadian clock enables anticipation of the day/night cycle in animals ranging from cnidarians to mammals. Circadian rhythms are generated through a transcription-translation feedback loop (TTFL or pacemaker) with CLOCK as a conserved positive factor in animals. However, CLOCK's functional evolutionary origin and mechanism of action in basal animals are unknown. In the cnidarian , pacemaker gene transcript levels, including (the ortholog), appear arrhythmic under constant darkness, questioning the role of NvCLK. Utilizing CRISPR/Cas9, we generated a allele mutant (), revealing circadian behavior loss under constant dark (DD) or light (LL), while maintaining a 24 hr rhythm under light-dark condition (LD). Transcriptomics analysis revealed distinct rhythmic genes in wild-type (WT) polypsunder LD compared to DD conditions. In LD, polyps exhibited comparable numbers of rhythmic genes, but were reduced in DD. Furthermore, under LD, the polyps showed alterations in temporal pacemaker gene expression, impacting their potential interactions. Additionally, differential expression of non-rhythmic genes associated with cell division and neuronal differentiation was observed. These findings revealed that a light-responsive pathway can partially compensate for circadian clock disruption, and that the gene has evolved in cnidarians to synchronize rhythmic physiology and behavior with the diel rhythm of the earth's biosphere.
Topics: Animals; Circadian Rhythm; Circadian Clocks; Sea Anemones; CLOCK Proteins; Photoperiod; Cnidaria
PubMed: 38743049
DOI: 10.7554/eLife.89499 -
The ISME Journal Jan 2024Temperate phages can interact with bacterial hosts through lytic and lysogenic cycles via different mechanisms. Lysogeny has been identified as the major form of...
Temperate phages can interact with bacterial hosts through lytic and lysogenic cycles via different mechanisms. Lysogeny has been identified as the major form of bacteria-phage interaction in the coral-associated microbiome. However, the lysogenic-to-lytic switch of temperate phages in ecologically important coral-associated bacteria and its ecological impact have not been extensively investigated. By studying the prophages in coral-associated Halomonas meridiana, we found that two prophages, Phm1 and Phm3, are inducible by the DNA-damaging agent mitomycin C and that Phm3 is spontaneously activated under normal cultivation conditions. Furthermore, Phm3 undergoes an atypical lytic pathway that can amplify and package adjacent host DNA, potentially resulting in lateral transduction. The induction of Phm3 triggered a process of cell lysis accompanied by the formation of outer membrane vesicles (OMVs) and Phm3 attached to OMVs. This unique cell-lysis process was controlled by a four-gene lytic module within Phm3. Further analysis of the Tara Ocean dataset revealed that Phm3 represents a new group of temperate phages that are widely distributed and transcriptionally active in the ocean. Therefore, the combination of lateral transduction mediated by temperate phages and OMV transmission offers a versatile strategy for host-phage coevolution in marine ecosystems.
Topics: Halomonas; Anthozoa; Prophages; Animals; Lysogeny; Transduction, Genetic; Mitomycin
PubMed: 38739683
DOI: 10.1093/ismejo/wrae085 -
ELife May 2024Neuropeptides are ancient signaling molecules in animals but only few peptide receptors are known outside bilaterians. Cnidarians possess a large number of G...
Neuropeptides are ancient signaling molecules in animals but only few peptide receptors are known outside bilaterians. Cnidarians possess a large number of G protein-coupled receptors (GPCRs) - the most common receptors of bilaterian neuropeptides - but most of these remain orphan with no known ligands. We searched for neuropeptides in the sea anemone and created a library of 64 peptides derived from 33 precursors. In a large-scale pharmacological screen with these peptides and 161 GPCRs, we identified 31 receptors specifically activated by 1 to 3 of 14 peptides. Mapping GPCR and neuropeptide expression to single-cell sequencing data revealed how cnidarian tissues are extensively connected by multilayer peptidergic networks. Phylogenetic analysis identified no direct orthology to bilaterian peptidergic systems and supports the independent expansion of neuropeptide signaling in cnidarians from a few ancestral peptide-receptor pairs.
Topics: Animals; Sea Anemones; Neuropeptides; Receptors, G-Protein-Coupled; Phylogeny; Signal Transduction
PubMed: 38727714
DOI: 10.7554/eLife.90674 -
ELife May 2024Studies of the starlet sea anemone provide important insights into the early evolution of the circadian clock in animals.
Studies of the starlet sea anemone provide important insights into the early evolution of the circadian clock in animals.
Topics: Animals; Biological Evolution; Circadian Clocks; Circadian Rhythm; Cnidaria; Sea Anemones
PubMed: 38716806
DOI: 10.7554/eLife.98512 -
Science Advances May 2024Many Caribbean coral reefs are near collapse due to various threats. An emerging threat, stony coral tissue loss disease (SCTLD), is spreading across the Western...
Many Caribbean coral reefs are near collapse due to various threats. An emerging threat, stony coral tissue loss disease (SCTLD), is spreading across the Western Atlantic and Caribbean. Data from the U.S. Virgin Islands reveal how SCTLD spread has reduced the abundance of susceptible coral and crustose coralline algae and increased cyanobacteria, fire coral, and macroalgae. A Caribbean-wide structural equation model demonstrates versatility in reef fish and associations with rugosity independent of live coral. Model projections suggest that some reef fishes will decline due to SCTLD, with the largest changes on reefs that lose the most susceptible corals and rugosity. Mapping these projected declines in space indicates how the indirect effects of SCTLD range from undetectable to devastating.
Topics: Animals; Coral Reefs; Anthozoa; Caribbean Region; Fishes; Ecosystem
PubMed: 38701216
DOI: 10.1126/sciadv.adk6808 -
PeerJ 2024Iron (Fe) plays a fundamental role in coral symbiosis, supporting photosynthesis, respiration, and many important enzymatic reactions. However, the extent to which...
Iron (Fe) plays a fundamental role in coral symbiosis, supporting photosynthesis, respiration, and many important enzymatic reactions. However, the extent to which corals are limited by Fe and their metabolic responses to inorganic Fe enrichment remains to be understood. We used respirometry, variable chlorophyll fluorescence, and O microsensors to investigate the impact of increasing Fe(III) concentrations (20, 50, and 100 nM) on the photosynthetic capacity of two Mediterranean coral species, and . While the bioavailability of inorganic Fe can rapidly decrease, we nevertheless observed significant physiological effects at all Fe concentrations. In , exposure to 50 nM Fe(III) increased rates of respiration and photosynthesis, while the relative electron transport rate (rETR(II)) decreased at higher Fe(III) exposure (100 nM). In contrast, reduced respiration, photosynthesis rates, and maximum PSII quantum yield (F/F) across all iron enrichments. Both corals exhibited increased hypoxia (<50 µmol O L) within their gastric cavity at night when exposed to 50 and 100 nM Fe(III), leading to increased polyp contraction time and reduced O exchange with the surrounding water. Our results indicate that , but not , might be limited in Fe for achieving maximal photosynthetic efficiency. Understanding the multifaceted role of iron in corals' health and their response to environmental change is crucial for effective coral conservation.
Topics: Anthozoa; Animals; Photosynthesis; Iron; Oxygen; Mediterranean Sea; Symbiosis
PubMed: 38699194
DOI: 10.7717/peerj.17259 -
Scientific Reports May 2024Globally tropical Scleractinian corals have been a focal point for discussions on the impact of a changing climate on marine ecosystems and biodiversity. Research into...
Globally tropical Scleractinian corals have been a focal point for discussions on the impact of a changing climate on marine ecosystems and biodiversity. Research into tropical Scleractinian corals, particularly the role and breakdown of photoendosymbiosis in response to warming, has been prolific in recent decades. However, research into their subtropical, temperate, cold- and deep-water counterparts, whose number is dominated by corals without photoendosymbiosis, has not been as prolific. Approximately 50% of Scleractinian corals (> 700 species) do not maintain photoendosymbiosis and as such, do not rely upon the products of photosynthesis for homeostasis. Some species also have variable partnerships with photendosymbionts depending on life history and ecological niche. Here we undertake a systematic map of literature on Scleractinian corals without, or with variable, photoendosymbiosis. In doing so we identify 482 publications spanning 5 decades. In mapping research effort, we find publications have been sporadic over time, predominately focusing on a limited number of species, with greater research effort directed towards deep-water species. We find only 141 species have been studied, with approximately 30% of the total identified research effort directed toward a single species, Desmophyllum pertusum, highlighting significant knowledge gaps into Scleractinian diversity. We find similar limitations to studied locations, with 78 identified from the global data, of which only few represent most research outputs. We also identified inconsistencies with terminology used to describe Scleractinia without photoendosymbiosis, likely contributing to difficulties in accounting for their role and contribution to marine ecosystems. We propose that the terminology requires re-evaluation to allow further systematic assessment of literature, and to ensure it's consistent with changes implemented for photoendosymbiotic corals. Finally, we find that knowledge gaps identified over 20 years ago are still present for most aphotoendosymbiotic Scleractinian species, and we show data deficiencies remain regarding their function, biodiversity and the impacts of anthropogenic stressors.
Topics: Anthozoa; Animals; Symbiosis; Biodiversity; Photosynthesis; Ecosystem; Climate Change; Coral Reefs
PubMed: 38698199
DOI: 10.1038/s41598-024-60794-0 -
Scientific Reports Apr 2024Mutualism profoundly affects the morphology and ecological evolution of both hosts and symbionts involved. Heterocyathus is a solitary scleractinian coral that lives on...
Mutualism profoundly affects the morphology and ecological evolution of both hosts and symbionts involved. Heterocyathus is a solitary scleractinian coral that lives on soft substrata, and sipunculan worms live symbiotically in the tube-like cavities (orifice) inside the coral skeletons. This habitat provides protection to the sipunculan worms against predators and-owing to the mobility of the worms-prevents the coral from being buried with sediments. The orifice growth is closely related to the symbiont sipunculan worms; however, this has not been previously elucidated. Here, we clarified the growth process of scleractinian coral orifices and the influence of sipunculan activity on this. The orifices were originally formed by rapid accretion deposits. The coral soft tissue enveloping the growth edge of the orifice repeatedly retreated to the outer side due to direct damage to the soft part and/or excessive stress caused by the rubbing of the sipunculan through locomotion, excretion, and feeding behaviour. This resulted in a toppled-domino microskeletal structure appearance and maintenance of the orifice growth. These outcomes demonstrate the first example of the direct influence of symbionts on the skeletal morphogenesis of scleractinian corals. The mutualism between the two organisms is maintained by the beneficial confrontation in forming orifices.
Topics: Animals; Anthozoa; Symbiosis; Adaptation, Physiological; Ecosystem; Coral Reefs
PubMed: 38684737
DOI: 10.1038/s41598-023-49631-y -
Molecular Biology and Evolution May 2024Gene duplication is a major force driving evolutionary innovation. A classic example is generating new animal toxins via duplication of physiological protein-encoding...
Gene duplication is a major force driving evolutionary innovation. A classic example is generating new animal toxins via duplication of physiological protein-encoding genes and recruitment into venom. While this process drives the innovation of many animal venoms, reverse recruitment of toxins into nonvenomous cells remains unresolved. Using comparative genomics, we find members of the Membrane Attack Complex and Perforin Family (MAC) have been recruited into venom-injecting cells (cnidocytes), in soft and stony corals and sea anemones, suggesting that the ancestral MAC was a cnidocyte expressed toxin. Further investigation into the model sea anemone Nematostella vectensis reveals that three members have undergone Nematostella-specific duplications leading to their reverse recruitment into endomesodermal cells. Furthermore, simultaneous knockdown of all three endomesodermally expressed MACs leads to mis-development, supporting that these paralogs have nonvenomous function. By resolving the evolutionary history and function of MACs in Nematostella, we provide the first proof for reverse recruitment from venom to organismal development.
Topics: Animals; Sea Anemones; Evolution, Molecular; Perforin; Gene Duplication; Cnidarian Venoms; Phylogeny; Multigene Family
PubMed: 38676945
DOI: 10.1093/molbev/msae082 -
Marine Drugs Apr 2024Three pairs of enantiomers (-)-the new 12-aloesol () and two new fatty acids ( and )-and one new natural product () together three known compounds (-) were isolated from...
Three pairs of enantiomers (-)-the new 12-aloesol () and two new fatty acids ( and )-and one new natural product () together three known compounds (-) were isolated from a coral-reef-derived sp. SCSIO 66814. Their structures were determined through extensive spectroscopic analysis, chiral analysis, and single-crystal X-ray diffraction data. Compounds and were presumed to be intermediates for further generating homononactic acid () and nonactic acid, and the latter two molecules were able to act as precursors to form macrotetrolides with remarkable biological activity. The isolation of related precursors, compounds -, provided more evidence to support the proposal of a plausible biosynthetic pathway for nonactic acid and its homologs. Additionally, (+)- exhibited a weak activity against DPPH radicals.
Topics: Streptomyces; Chromones; Stereoisomerism; Anthozoa; Animals; Crystallography, X-Ray; Fatty Acids; Biological Products; Molecular Structure
PubMed: 38667798
DOI: 10.3390/md22040181