Biology subjects

Vilanova-Cuevas, B.

Publications and source records attributed to Vilanova-Cuevas, B..

4 recordsLinked to original sources

bioRxiv2026

Host-independent persistence of the Diadema antillarum Scuticociliatosis Philaster clade in coastal environments

The mass mortality of the keystone herbivore Diadema antillarum in the Caribbean was caused by the pathogenic ciliate from the Diadema antillarum Scuticociliatosis Philaster clade (DaScPc). Despite its confirmed pathogenicity, the environmental distribution and persistence strategies of DaScPc outside its host remain poorly understood. We used quantitative PCR, nested PCR, and Sanger sequencing across a 16-month time series and broad geographic surveys to investigate its ecological dynamics and potential environmental reservoirs. Sequencing-confirmed detections at a Florida coastal site devoid of D. antillarum show that DaScPc is a natural, host-independent component of the reef environment. Molecular detection on coral and macroalgal surfaces and in the plankton fraction indicates that multiple substrates can harbor the ciliate. Temporal observations revealed emerging trends with macroalgal cover and reef productivity, though no direct correlations were observed. Geographically, DaScPc was absent from outbreak sites in Panama and Reunion. Together, this data suggests spatial patchiness and a cryptic "boom-and-bust" lifestyle in which the organism persists at low abundance between outbreaks. The co-occurrence of a related nonpathogenic ciliate (Acropora/CHN/2009) further underscores the ecological complexity of the Philaster clade. These findings broaden understanding of DaScPc ecology, confirming environmental persistence independent of its host and suggesting that parasitism may be intermittent, triggered by changing environmental conditions. This work highlights the need for higher-resolution surveillance and long-term monitoring to link ecosystem processes with the reemergence of marine disease in vulnerable coral reef systems. ImportanceThe 2022 mass mortality of the sea urchin Diadema antillarum devastated Caribbean coral reefs, yet little is known about how the pathogenic ciliate responsible for the event persists in nature. We show that the Diadema antillarum Scuticociliatosis Philaster clade (DaScPc) occurs in reef environments even where the host (D. antillarum) is absent, indicating that it can persist independently of its host. Our findings suggest that DaScPc occupies a cryptic ecological niche within reef microbial communities and may follow a "boom-bust" dynamic, fluctuating between rare environmental states and occasional proliferation. Although direct environmental drivers remain unresolved, emerging trends with macroalgal cover and reef productivity highlight the potential influence of ecosystem conditions on ciliate abundance. This work broadens the understanding of how marine pathogens persist between outbreaks and underscores the importance of environmental surveillance for predicting and mitigating future disease events on coral reefs.

microbiology↗

bioRxiv2025

Scuticociliate Detection and Microbiome Composition in Museum Collections of Diadema Antillarum

BackgroundThe mass mortality of the long-spined sea urchin Diadema antillarum has caused widespread ecological changes across Caribbean reefs, with recent studies identifying the etiological agent as pathogenic ciliate designated as a D. antillarum Scuticociliatosis Philaster-clade (DaScPc). The origin and ecological trajectory of DaScPc remain unresolved, raising critical questions about whether it represents a novel introduction or a resident commensal symbiont that transitioned into pathogenicity. MethodsTo address this, we tested 50 individual preserved museum specimens of D. antillarum collected between 1960 and 2020, with targeted PCR amplification of ciliate 18S, 28S, and 5.8S/ITS rRNA genes for spine, body wall, and coelomic fluid samples (n=100). Following up on recent work that identified bacterial biomarkers of DaSc, we also characterized the microbial communities associated with these museum specimens using 16S rRNA amplicon sequencing. Results. Our results reveal the presence of identical DaScPc 18S rRNA sequences in 21% of tested samples, 28S rRNA PCR yielded sequences at 96-98 % nt identity in only 2% of the tested samples, and we got no amplification from the 5.8S/ITS region. While these findings suggest possible long-term persistence or repeated emergence of this ciliate, the lack of 28S rRNA matches and lack of detection of ITS2 demonstrates that DaScPc 18S rRNA gene detections may be false positives for the ciliate over a highly conserved rRNA region. The microbial composition of the samples didnt yield any of the previously identified disease-associated bacterial biomarkers and showed large shifts in the overall microbial community based on collection period and the facility where the samples are housed. This study demonstrates that museum-preserved echinoderm tissues retain ecologically informative microbial DNA and establishes a molecular framework for disentangling pathogen provenance and its caveats. It also highlights the value and limitations of natural history collections in reconstructing marine disease ecology.

microbiology↗

bioRxiv2023

Transglobal spread of an ecologically significant sea urchin parasite

Mass mortality of the dominant coral reef herbivore Diadema antillarum in the Caribbean in the early 1980s led to a persistent phase shift from coral-to algal-dominated reefs. In 2022, a scuticociliate most closely related to Philaster apodigitiformis caused further mass mortality of D. antillarum across the Caribbean, leading to >95% mortality at affected sites. Mortality was also reported in the related species Diadema setosum in the Mediterranean in 2022, where urchins experienced gross signs compatible with scuticociliatosis. However, the causative agent of the Mediterranean outbreak has not yet been determined. In April 2023, mass mortality of D. setosum occurred along the Sultanate of Omans coastline. Urchins displayed signs compatible with scuticociliatosis including abnormal behavior, drooping and loss of spines, followed by tissue necrosis and death. Here we report the detection of an 18S rRNA gene sequence in abnormal urchins from Muscat, Oman that is identical to the Philaster strain responsible for D. antillarum mass mortality in the Caribbean. We also show that scuticociliatosis signs can be elicited in D. setosum by experimental challenge with the cultivated Philaster strain associated with Caribbean scuticociliatosis. These results demonstrate the Philaster sp. associated with D. antillarum mass mortality has rapidly spread to geographically distant coral reefs, compelling global-scale awareness and monitoring for this devastating condition through field surveys, microscopy, and molecular microbiological approaches, and prompting investigation of long-range transmission mechanisms.

ecology↗

bioRxiv2022

Unique features of the gut microbiome characterized in animal models of Angelman Syndrome

A large subset of patients with Angelman syndrome (AS) suffer from concurrent gastrointestinal (GI) issues, including constipation, poor feeding, and reflux. AS is caused by the loss of ubiquitin ligase E3A (UBE3A) gene expression in the brain. Clinical features of AS, which include developmental delays, intellectual disability, microcephaly, and seizures, are primarily due to the deficient expression or function of the maternally inherited UBE3A allele. The association between neurodevelopmental delay and GI disorders is part of the increasing evidence suggesting a link between the brain and the gut microbiome via the microbiota-gut-brain (MGB) axis. To investigate the associations between colonization of the gut microbiota in AS, we characterized the fecal microbiome in three animal models of AS containing maternal deletions of Ube3A, including mouse, rat, and pig, using 16S ribosomal RNA amplicon sequencing. Overall changes in the microbial composition of all three animal models of AS in both the phylum and genus levels of bacterial abundance were identified. Specific bacterial groups were significantly increased across all animal models, including: Lachnospiraceae Incertae sedis, Desulfovibrios sp., and Odoribacter, which have been correlated with neuropsychiatric disorders. Taken together, these findings suggest that specific changes to the local environment in the gut are driven by a Ube3a maternal deletion, unaffected by varying housing conditions and are prominent and detectable across multiple small and large model species. These findings may begin to uncover the underlying mechanistic causes of GI disorders in AS patients and provide future therapeutic options for AS patients. IMPORTANCEAngelman syndrome (AS) associated gastrointestinal (GI) symptoms significantly impact quality of life in patients. Using AS models in mouse, rat, and pig, AS animals showed impaired colonization of the gut microbiota compared to wild type (healthy) control animals. Unique changes in AS microbiomes across all three animal models may be important in causing GI symptoms and may help to identify ways to treat these comorbidities in patients in the future.

microbiology↗