Jean-Baptiste Fini

Microplastics have spread through every ecosystem studied. Yet, documenting their spatiotemporal distribution remains challenging, particularly in marine environments where sampling is costly and difficult. Archived specimens in zoological biobanks offer an underused resource for investigating microplastic contamination across all marine environments. However, their use requires careful experimental design. This study proposes an approach for detecting microplastics in biobanked sea cucumbers from the Atlantic Ocean and Mediterranean Sea. As deposit-feeders, they are in frontline of microplastics sinking to the seafloor and should thus give insights to the level of exposure to microplastic pollution in their natural habitats. We address and overcome critical methodological challenges associated with preserved specimens. We first verified that preservation solvents do not introduce significant external contamination. We then adapted state-of-the-art sample preparation protocols to quantify five common plastic polymers from sea cucumber intestines using pyrolysis–gas chromatography–tandem mass spectrometry after chemical digestion of the intestines. The optimized method demonstrates excellent robustness, with negligible procedural contamination and high purification rates that effectively eliminate tissue matrix before polymer analysis. Our analytical approach achieves low detection limits while confidently distinguishing polyethylene from confounding organic compounds like lipids. Analyzed specimens contained total polymer concentrations ranging from 9.4 to 169.2 µg per gram of dry matter, consistent with levels found in other marine organisms, and predominantly polyethylene terephthalate and polystyrene. This approach transforms existing museum collections into invaluable resources for documenting microplastic pollution across time and space.

Abnormalities are indispensable for studying normal biological processes and mechanisms. In the present work, we draw attention to the remarkable phenomenon of a perpetually and robustly upregulated gene, the thyroglobulin gene ( Tg ). The gene is expressed in the thyroid gland and, as it has been recently demonstrated, forms so-called transcription loops, easily observable by light microscopy. Using this feature, we show that Tg is expressed at a high level from the moment a thyroid cell acquires its identity and both alleles remain highly active over the entire life of the cell, i.e. for months or years depending on the species. We demonstrate that this high upregulation is characteristic of thyroglobulin genes in all major vertebrate groups. We provide evidence that Tg is not influenced by the thyroid hormone status, does not oscillate round the clock and is expressed during both the exocrine and endocrine phases of thyrocyte activity. We conclude that the thyroglobulin gene represents a valuable model to study the maintenance of a high transcriptional upregulation. SUMMARY STATEMENT: The thyroglobulin gene is highly and permanently expressed in thyrocytes of all vertebrates, at any condition and round the clock, offering a unique model to study mechanisms of high upregulation maintenance and chromatin dynamics

Prenatal exposure to a mixture (MIX N) of eight endocrine-disrupting chemicals has been associated with language delay in children in a Swedish pregnancy cohort. A novel approach was proposed linking this epidemiological association with experimental evidence, where the effect of MIX N on thyroid hormone signaling was assessed using the Xenopus eleuthero-embryonic thyroid assay (XETA OECD TG248). From this experimental data, a point of departure (PoD) was derived based on OECD guidance. Our aim in the current study was to use updated toxicokinetic models to compare exposures of women of reproductive age in the US population to MIX N using a Similar Mixture Approach (SMACH). Based on our findings, 66% of women of reproductive age in the US (roughly 38 million women) had exposures sufficiently similar to MIX N. For this subset, a Similar Mixture Risk Index (SMRI_HI) was calculated comparing their exposures to the PoD. Women with SMRI_HI > 1 represent 1.1 million women of reproductive age. Older women, Mexican American and other/multi race women were less likely to have high SMRI_HI values compared to Non-Hispanic White women. These findings indicate that a reference mixture of chemicals identified in a Swedish cohort—and tested in an experimental model for establishment of (PoDs)—is also of health relevance in a US population.