Biology subjects

Scucchia, F.

Publications and source records attributed to Scucchia, F..

5 recordsLinked to original sources

bioRxiv2025

Contrasting temperature-induced gene network rewiring and isoform switching underlie relative thermal tolerance of coral species

Organismal thermal tolerance will shape future coral reef diversity and abundance, as ocean warming drives extensive bleaching and mortality through increasingly frequent marine heatwaves. Coral thermal tolerance varies markedly among species, reflecting differences in physiology underpinned by molecular regulatory mechanisms. Gene expression plasticity enables transcriptional adjustments to environmental stress, while alternative splicing and isoform switching further expand molecular adaptability by altering transcript diversity and abundance. Because genes function within combinatorial networks, changes in these network members and in the identity of highly influential hub genes can reveal higher-order biological reorganization under stress. Yet, the contribution of isoform switching to gene network dynamics remains unknown in corals. Here we integrate physiology, gene network topology, hub genes dynamics, and isoform switching across three Hawaiian corals, Porites compressa, Montipora capitata, and Pocillopora acuta, to identify molecular processes shaping thermal performance. We show that the interplay between expression plasticity, hub gene rearrangement, and isoform switching drives species-specific thermal tolerance. Network analysis uncovered extensive rewiring and temperature-responsive hub genes turnover regulated by switches in isoform usage. The most thermally tolerant species, P. compressa, shows high energy reserves, stable constitutive gene expression and continuous isoform adjustments across temperatures, while fine-tuning thermal response through dedicated hub genes. In contrast, the most thermally sensitive species, P. acuta, shows lowest energy reserves, with broad transcriptomic shifts and isoform switching controlling the reorganization of network leadership at high temperatures. Together, these findings identify isoform switching as a newly recognized regulatory mechanism contributing to coral thermal resilience and species persistence in warming oceans.

ecology↗

bioRxiv2025

Exposure to a gradient of warming and acidification highlights physiological, molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits

Ocean warming and acidification are among the biggest threats to the persistence of coral reefs. Organismal stress tolerance thresholds are life stage specific, can vary across levels of biological organization, and also depend on natural environmental variability. Here, we exposed the early life stages of Pocillopora acuta in K[a]ne ohe Bay, Hawai i, USA, a common reef-building coral throughout the Pacific, to projected ocean warming and acidification scenarios. We measured ecological, physiological, biomineralization, and molecular responses across the critical transition from larvae to newly settled recruits following 6 days of exposure to diel fluctuations in temperature and pH in Control (26.8-27.9{degrees}C, 7.82-7.96 pHTotal), Mid (28.4-29.5{degrees}C, 7.65-7.79 pHTotal) and High conditions (30.2-31.5{degrees}C, 7.44-7.59 pHTotal). We found that P. acuta early life stages are capable of survival, settlement, and calcification under all scenarios. The High conditions, however, caused a significant reduction in survival and settlement capacity, with changes in the skeletal fiber deposition patterns. In contrast to a limited impact on the expression of biomineralization genes, the dominant transcriptomic response to the High conditions relative to the two other treatments included depressed metabolism, reduced ATP production and increased activity of DNA damage-repair processes. Collectively, our findings indicate that corals living in environments with large diurnal fluctuations in seawater temperature and pH, such as K[a]ne ohe Bay, can tolerate exposure to moderate projected increased temperature and reduced pH. However, under more severe environmental conditions significant negative effects on coral cellular metabolism and overall organismal survival jeopardize species fitness and recruitment.

molecular biology↗

bioRxiv2023

A novel in vivo system to study coral biomineralization in the starlet sea anemone (Nematostella vectensis)

Coral reefs are important for maintaining healthy marine ecosystems and are declining rapidly due to increasing environmental stresses. Coral conservation efforts require a mechanistic understanding of how these stresses may disrupt biomineralization, but progress in this area has been slow primarily because corals are not easily amenable to laboratory research. Some cellular characteristics of biomineralization are well characterized, such as the role of carbonic anhydrases, the polarized secretion of ions, and the secretion of "intrinsically disordered proteins" (IDPs) into extracellular microenvironments. We highlight how the starlet sea anemone (Nematostella vectensis) can serve as a tractable model to interrogate the cellular mechanisms of coral biomineralization. We have developed transgenic constructs using genes involved in biomineralization from several animal phyla that can be injected into Nematostella zygotes. These constructs are designed so translated proteins may be purified using TEV protease or Histidine tags to study their physicochemical properties. Using a fluorescent tag, we confirm ectopic expression of the coral biomineralizing protein SpCARP1 in live Nematostella embryos and adults and demonstrate via calcein staining that calcium ions co-localize with SpCARP1 in carbonate and calcium enriched seawater. Our findings suggest that SpCARP1 can induce the formation of amorphous calcium carbonate precursors in N. vectensis, consistent with its suspected role in the early stages of coral biomineralization. These results lay a fundamental groundwork for establishing N. vectensis as a novel in vivo system to explore the evolutionary and cellular mechanisms of biomineralization, improve coral conservation efforts, and even develop novel biomaterials. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/560932v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@1170b4eorg.highwire.dtl.DTLVardef@1e7491corg.highwire.dtl.DTLVardef@1710cd1org.highwire.dtl.DTLVardef@100743b_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2021

Energetics but not development is impacted in coral embryos exposed to ocean acidification

In light of the chronic stress and mass mortality reef-building corals face under climate change, it is critical to understand the processes essential to reef persistence and replenishment, including coral reproduction and development. Here we quantify gene expression and size sensitivity to ocean acidification across a set of developmental stages in the rice coral, Montipora capitata. Embryos and swimming larvae were exposed to pH treatments 7.8 (Ambient), 7.6 (Low) and 7.3 (Xlow) from fertilization to 9 days post-fertilization. Embryo and larval volume, and stage-specific gene expression were compared between treatments to determine the effects of acidified seawater on early development. While there was no measurable size differentiation between fertilized eggs and prawn chips exposed to pH 7.8, 7.6, and 7.3, early gastrula and planula raised in reduced pH treatments were significantly smaller than those raised in ambient seawater, suggesting an energetic cost to developing under low pH. However, no differentially expressed genes emerged until 9 days post-fertilization. Notably, gene expression patterns of larvae developing at pH 7.8 and pH 7.3 were more similar than those developing at pH 7.6. Larvae from pH 7.6 showed upregulation of genes involved in cell division, regulation of transcription, lipid metabolism, and oxidative stress in comparison to the other two treatments. While low pH appears to increase energetic demands and trigger oxidative stress, the developmental process is robust to this at a molecular level, with swimming larval stage reached in all pH treatments. Summary statementThis developmental time series tracks the physiological and transcriptomic outcomes of early coral development under ambient pH (pH 7.8), and two low pH conditions (pH 7.6 and 7.3).

physiology↗

bioRxiv2021

Combined responses of primary coral polyps and their algal endosymbionts to decreasing seawater pH

With coral reefs declining globally, resilience of these ecosystems hinges on successful coral recruitment. However, knowledge of the acclimatory and/or adaptive potential in response to environmental challenges such as ocean acidification (OA) in earliest life stages is limited. Our combination of physiological measurements, microscopy, computed tomography techniques and gene expression analysis allowed us to thoroughly elucidate the mechanisms underlying the response of early life stages of corals, together with their algal partners, to the projected decline in oceanic pH. We observed extensive physiological, morphological and transcriptional changes in surviving recruits, and the transition to a less-skeleton/more-tissue phenotype. We found that decreased pH conditions stimulate photosynthesis and endosymbiont growth, and gene expression potentially linked to photosynthates translocation. Our unique holistic study discloses the previously unseen intricate net of interacting mechanisms that regulate the performance of these organisms in response to OA.

developmental biology↗