Biology subjects

Miglietta, M. P.

Publications and source records attributed to Miglietta, M. P..

6 recordsLinked to original sources

bioRxiv2026

Can an original be found? Mitochondrial species identity does not predict nuclear genome similarity in the photosymbiotic jellyfish Cassiopea andromeda and C. xamachana

The Upside-Down Jellyfish, Cassiopea, has become a mainstay of cnidarian photosymbiosis research. Two nominal sister species, C. xamachana and the globally introduced C. andromeda, supply most of the medusae used in American and European laboratory research within this genus. As founder identity can shape experimental outcomes, here we utilize whole genome resequencing of 21 Cassiopea medusae spanning the Florida Keys, Bocas del Toro (Panama), and a European laboratory line, to ask whether mitochondrial species assignment predicts nuclear genome identity. Across multiple population structure analyses using the nuclear genome, Floridian Cassiopea carrying C. xamachana or C. andromeda mitotypes are indistinguishable, and geography is the dominant axis of nuclear genetic structure. A population tree that groups the two Floridian mitotypes as a single interbreeding unit is strongly supported (Patterson's D {approx} 0.0, Z = 0.02), whereas a tree that respects mitochondrial species boundaries is rejected (D = 0.42, Z = 20.8). Strikingly, the European "true" C. andromeda line clusters with Panamanian C. xamachana rather than with Floridian C. andromeda-mitotype animals. From the same sequencing effort, we recover evidence of symbiont community variability (Cladocopium) in Panama and assemble two near-complete Tenacibaculum and Endozoicomonas metagenomically-assembled genomes from Floridian host tissue. Together these results indicate that the C. andromeda/C. xamachana hybridization zone may extend across ocean basins, and that a "pure" original of either species may be difficult to find. We urge Cassiopea researchers to establish new European laboratory lines with described genomes.

ecology↗

bioRxiv2026

Jelly belly: Recovery of fish eDNA from Cassiopea medusae gastrovascular cavities across the Florida Keys

Ranges of small benthic fauna are notoriously difficult to assess. In some of these cases, modern eDNA methods can shed light on species occurrence. Here we conduct an exploratory study on the fish eDNA recoverable from the gastrovascular cavities of the easy-to-sample pore water siphoning benthic invertebrate, Cassiopea, across six sites within the Florida Keys. Twenty-seven fish 12S identities were recovered from water samples, two from sediment samples, and seventeen from Cassiopea gut swabs. In total, thirty-two different species were identified from nineteen families, including one shark species (Ginglymostoma cirratum), and five species of cryptobenthic reef fishes (f: Gobiidae, Labrisomidae). Additionally, five species were identified from medusae samples that were not recovered in water or sediment samples. The species identities recovered may provide insight into the fish in direct proximity to Cassiopea assemblages, as well as indicate that Cassiopea may accrue disproportionate eDNA from cryptobenthic reef fish compared to surrounding environmental samples. The unorthodox sampling technique of using eDNA recovered from jellyfish stomachs yields another avenue for epibenthic community data acquisition.

ecology↗

bioRxiv2026

Combination of indomethacin and temperature produces reliable strobilation in Cassiopea xamachana but batch effects create high variability in ephyra outcomes

Indomethacin and temperature shocks are both widely used to induce ephyra production in Cassiopea polyps, yet the combined effect of these stimuli on strobilation rate, ephyra viability, and polyp survivorship has not been systematically examined. We designed a full factorial experiment crossing five indomethacin concentrations (0, 10, 25, 50, and 75 {micro}M) with four temperature treatments (22, 25, 28, and 31{degrees}C) across three independent experimental trials, exposing a total of 288 individual Cassiopea xamachana polyps for 29 days. Overall, 207 of 288 polyps (71.9%) released at least one ephyra. Temperature was the stronger predictor of strobilation: higher temperatures substantially increased the probability of producing a healthy ephyra (log-odds: +0.327 per {degrees}C; {chi}{superscript 2} p = 6.5 x 10-5), while indomethacin had a smaller but significant positive effect (log-odds: +0.024 per {micro}M; {chi}{superscript 2} p = 0.035). The two stimuli acted independently without significant interaction on healthy ephyra production ({chi}{superscript 2} p = 0.87), although their interaction on total ephyra production (including unhealthy releases) was significant ({chi}{superscript 2} p = 1.0 x 10-9). Notably, low indomethacin concentrations (10 and 25 {micro}M) significantly increased the proportion of unhealthy ephyrae relative to seawater controls (paired t-tests: p = 0.035 and p = 0.006, respectively), while higher concentrations (50-75 {micro}M) did not. Polyp survivorship declined significantly at 28{degrees}C and 31{degrees}C but was unaffected by indomethacin. Trial replicate was the most statistically significant predictor of every outcome measured with the third trial producing near-universal strobilation but zero viable ephyrae, a result of an unidentified perturbation. These results indicate that temperature elevation to 28-31{degrees}C is the most reliable induction strategy for C. xamachana and that low indomethacin concentrations should be avoided when ephyra quality is paramount. We also note that cryptic batch-level variables can overwhelm controlled factors and should be addressed in future experimental designs.

zoology↗

bioRxiv2026

Adaptive molecular convergence is pervasive across deep time and largely decoupled from phenotypic convergence

Researchers often infer evolutionary repeatability when selection scans implicate homologous genes in repeatedly evolved traits or ecologies. However, the causes and frequency of genome-scale molecular convergence remain unresolved, particularly over deep time. We show that adaptive molecular convergence-- excess convergence of nonsynonymous substitutions, consistent with positive selection--is pervasive across Medusozoa. Molecular convergence declines over time but persists among lineages separated by > 600 million years, exceeding null expectations based on random overlap. However, lineages sharing repeatedly evolved phenotypes (eyes, medusa loss, upright colonies) do not exhibit elevated molecular convergence relative to other comparisons. Instead, convergence is non-randomly distributed across genes and enriched for environment-facing functions, including metabolism, immunity, and xenobiotic processing, suggesting that widespread reuse of genes reflects multifaceted organism-environment interactions.

evolutionary biology↗

bioRxiv2025

A transcriptomic approach to understand genetic networks of regeneration, cell plasticity, and longevity of the Immortal Jellyfish Turritopsis dohrnii (Cnidaria, Hydrozoa)

When medusae of Turritopsis dohrnii are damaged, wounded, or exposed to otherwise lethal conditions, they revert to an earlier life cycle stage (the polyp) through an intermediate and transient benthic stage, the cyst, thus effectively escaping death. By employing a super transcriptome approach, we profile how the expression putative homologs of genes involved in regeneration, pluripotency, and longevity, change throughout life cycle stages of T. dorhnii. We follow the expression of putative homologs of Sirtuins, factors that control telomere maintenance, heat shock proteins (HSPs), and the Yamanaka transcription factor families (POU, Sox, Klf, Myc). We show that during its life cycle reversal, T. dohrnii manipulates genetic networks of high relevance in biomedical studies in mammals, such as SIRT3, POU factors, RTEL1, and HSP70/90. Our data showcase T. dohrnii as an in vivo research system that can contribute to understanding the genetic networks that regulate cell programming and ontogeny reversal.

genomics↗

bioRxiv2024

Bacterial communities of Cassiopea in the Florida Keys share major bacterial taxa with coral microbiomes

Interactions with microbial communities fundamentally shape metazoans physiology, development, and health across marine ecosystems. This is especially true in zooxanthellate (symbiotic algae-containing) cnidarians. In photosymbiotic anthozoans (eg. shallow water anemones and corals), the key members of the associated microbiota are increasingly well studied, however there is limited data on photosymbiotic scyphozoans (true jellyfish). Using 16S rRNA barcoding, we sampled the internal and external mucus of the zooxanthellate Upside- Down Jellyfish, Cassiopea xamachana throughout eight sites covering the full length of the Florida Keys. We find that across sites, these medusae to have low-diversity internal microbial communities distinct from the communities of their external surfaces and their environment. These internal communities are dominated by only three taxa: Endozoicomonas cf. atrinae, an uncultured novel Mycoplasma, and Vibrio cf. coralliilyticus. Cassiopea bell mucosal samples conform largely to the communities of surrounding sediment with the addition of Endozoicomonas cf. atrinae. The microbial taxa we identify associated with wild Florida Keys Cassiopea bear a strong resemblance to those found within photosymbiotic anthozoans, increasing the known links in ecological position between these groups.

ecology↗