Latest Publications

Bull Environ Contam Toxicol. 2023 Mar 15;110(3):65. doi: 10.1007/s00128-023-03701-z.

ABSTRACT

Rare earth elements (REEs) cerium (Ce) and lanthanum (La) and their combination were tested across a concentration range, from toxic (10-4 to 10-5 M) to lower concentrations (10-6 to 10-8 M) for their effects on sea urchin (Sphaerechinus granularis) sperm. A significantly decreased fertilization rate (FR) was found for sperm exposed to 10-5 M Ce, La and their combination, opposed to a significant increase of FR following 10-7 and 10-8 M REE sperm exposure. The offspring of REE-exposed sperm showed significantly increased developmental defects following sperm exposure to 10-5 M REEs vs. untreated controls, while exposure to 10-7 and 10-8 M REEs resulted in significantly decreased rates of developmental defects. Both of observed effects-on sperm fertilization success and on offspring quality-were closely exerted by Ce or La or their combination.

PMID:36922429 | PMC:PMC10017572 | DOI:10.1007/s00128-023-03701-z

Proc Biol Sci. 2023 Feb 22;290(1993):20221897. doi: 10.1098/rspb.2022.1897. Epub 2023 Feb 22.

ABSTRACT

The recent collapse of predatory sunflower sea stars (Pycnopodia helianthoides) owing to sea star wasting disease (SSWD) is hypothesized to have contributed to proliferation of sea urchin barrens and losses of kelp forests on the North American west coast. We used experiments and a model to test whether restored Pycnopodia populations may help recover kelp forests through their consumption of nutritionally poor purple sea urchins (Strongylocentrotus purpuratus) typical of barrens. Pycnopodia consumed 0.68 S. purpuratus d-1, and our model and sensitivity analysis shows that the magnitude of recent Pycnopodia declines is consistent with urchin proliferation after modest sea urchin recruitment, and even small Pycnopodia recoveries could generally lead to lower densities of sea urchins that are consistent with kelp-urchin coexistence. Pycnopodia seem unable to chemically distinguish starved from fed urchins and indeed have higher predation rates on starved urchins owing to shorter handling times. These results highlight the importance of Pycnopodia in regulating purple sea urchin populations and maintaining healthy kelp forests through top-down control. The recovery of this important predator to densities commonly found prior to SSWD, whether through natural means or human-assisted reintroductions, may therefore be a key step in kelp forest restoration at ecologically significant scales.

PMID:36809801 | PMC:PMC9943640 | DOI:10.1098/rspb.2022.1897

Front Immunol. 2023 Jan 16;13:1066510. doi: 10.3389/fimmu.2022.1066510. eCollection 2022.

ABSTRACT

The closely linked recombination activating genes (RAG1 and RAG2) in vertebrates encode the core of the RAG recombinase that mediates the V(D)J recombination of the immunoglobulin and T-cell receptor genes. RAG1 and RAG2 homologues (RAG1L and RAG2L) are present in multiple invertebrate phyla, including mollusks, nemerteans, cnidarians, and sea urchins. However, the function of the invertebrates' RAGL proteins is yet unknown. The sea urchins contain multiple RAGL genes that presumably originated in a common ancestral transposon. In this study, we demonstrated that two different RAG1L genes in the sea urchin Paracentrutus lividus (PlRAG1La and PlRAG1Lb) lost their mobility and, along with PlRAG2L, were fully domesticated to carry out different functions. We found that the examined echinoid RAGL homologues have distinct expression profiles in early developmental stages and in adult tissues. Moreover, the predicted structure of the proteins suggests that while PlRAG1La could maintain its endonuclease activity and create a heterotetramer with PlRAG2L, the PlRAG1Lb adopted a different function that does not include an interaction with DNA nor a collaboration with PlRAG2L. By characterizing the different RAG homologues in the echinoid lineage, we hope to increase the knowledge about the evolution of these genes and shed light on their domestication processes.

PMID:36726993 | PMC:PMC9885083 | DOI:10.3389/fimmu.2022.1066510

Dev Biol. 2023 Apr;496:52-62. doi: 10.1016/j.ydbio.2023.01.009. Epub 2023 Jan 27.

ABSTRACT

Ambulacrarians (echinoderms and hemichordates) are a sister group to chordates; thus, their larval cell-types may provide clues about evolution of chordate body plans. Although most genic information accumulated to date pertains to sea urchin embryogenesis, starfish embryogenesis represents a more ancestral mode than that of sea urchins. We performed single-cell RNA-seq analysis of cell-types from gastrulae and bipinnarial larvae of the starfish, Patiria pectinifera, and categorized them into 22 clusters, each of which is composed of cells with specific, shared profiles of development-relevant gene expression. Oral and aboral ectoderm, apical plate, hindgut or archenteron, midgut or intestine, pharynx, endomesoderm, stomodeum, and mesenchyme of the gastrulae, and neurons, ciliary bands, enterocoel and muscle of larvae were characterized by expression profiles of at least two relevant transcription factor genes and signaling molecular genes. Expression of Hox2, Hox7, Hox9/10, and Hox11/13b was detected in cells of clusters that form the larval enterocoel. By comparing homologous gene expression profiles in chordate embryos, we discuss and propose how the chordate body plan evolved from a deuterostome ancestor, from which the echinoderm body plan also evolved.

PMID:36717049 | DOI:10.1016/j.ydbio.2023.01.009

Biol Bull. 2022 Dec;243(3):315-327. doi: 10.1086/722800. Epub 2023 Jan 4.

ABSTRACT

AbstractAn explanation for variation in impacts of sea star wasting disease across asteroid species remains elusive. Although various traits have been suggested to play a potential role in sea star wasting susceptibility, currently we lack a thorough comparison that explores how life-history and natural history traits shape responses to mass mortality across diverse asteroid taxa. To explore how asteroid traits may relate to sea star wasting, using available data and recognizing the potential for biological correlations to be driven by phylogeny, we generated a supertree, tested traits for phylogenetic association, and evaluated associations between traits and sea star wasting impact. Our analyses show no evidence for a phylogenetic association with sea star wasting impact, but there does appear to be phylogenetic association for a subset of asteroid life-history traits, including diet, substrate, and reproductive season. We found no relationship between sea star wasting and developmental mode, diet, pelagic larval duration, or substrate but did find a relationship with minimum depth, reproductive season, and rugosity (or surface complexity). Species with the greatest sea star wasting impacts tend to have shallower minimum depth distributions, they tend to have their median reproductive period 1.5 months earlier, and they tend to have higher rugosities relative to species less affected by sea star wasting. Fully understanding sea star wasting remains challenging, in part because dramatic gaps still exist in our understanding of the basic biology and phylogeny of asteroids. Future studies would benefit from a more robust phylogenetic understanding of sea stars, as well as leveraging intra- and interspecific comparative transcriptomics and genomics to elucidate the molecular pathways responding to sea star wasting.

PMID:36716486 | DOI:10.1086/722800