Sea cucumbers lack vision and rely on chemical sensing to reproduce and survive. However, how they recognize and respond to environmental cues remains unknown. possible candidates are the odorant receptors (oRs), a diverse family of G protein-coupled receptors (GpcRs) involved in olfaction. The present study aimed at characterizing the chemosensory GPCRs in sea cucumbers. At least 246 distinct GpcRs, of which ca. 20% putative ORs, were found in a transcriptome assembly of putative chemosensory (tentacles, oral cavity, calcareous ring, and papillae/tegument) and reproductive (ovary and testis) tissues from Holothuria arguinensis (57 ORs) and in the Apostichopus japonicus genome (79 ORs). The sea cucumber ORs clustered with those of sea urchin and starfish into four main clades of gene expansions sharing a common ancestor and evolving under purifying selection. However, the sea cucumber oRs repertoire was the smallest among the echinoderms and the olfactory receptor signature motif LxxPxYxxxxxLxxxDxxxxxxxxP was better conserved in cluster OR-l1 which also had more members. oRs were expressed in tentacles, oral cavity, calcareous ring, and papillae/tegument, supporting their potential role in chemosensing. This study is the first comprehensive survey of chemosensory GpcRs in sea cucumbers, and provides the molecular basis to understand how they communicate. All living organisms perceive and respond to chemical cues in their environment, which mediate a variety of activities such as feeding, predator avoidance, mating and social behaviours 1,2. These cues can be detected over long and short distances, and include a large diversity of molecules ranging from amino acids and nucleic acids, to small volatile compounds, peptides and proteins (see review 3). To detect and discriminate chemical cues, animals have developed complex chemosensory organs, including the olfactory organs of vertebrates, which contain a large repertoire of chemosensory receptors 4. Although well characterized in some animals 5-7 , chemosensory receptors remain largely undescribed in many metazoan lineages. A large group of chemosensory receptors belong to the G protein-coupled receptors (GPCRs), one of the largest superfamilies of seven transmembrane domain receptors found in metazoans 8. GPCRs convert extracellular stimuli, ranging from small molecules and photons to peptides and proteins, into intracellular biochemical signals via multiple signalling cascades (mostly cAMP and calcium secondary messengers) 9. The large variety of ligands is reflected in the structural diversity of GPCRs which are classified into five main families based on their sequence similarity (GRAFS system): glutamate (G), rhodopsin (R), adhesion (A), frizzled (F) and secretin (S) 10. Chemosensory functions have been associated with the glutamate-receptor family and the rhodopsin-type family 11,12. The latter contains the largest number and the most diverse repertoire of GPCRs involved in vertebrate olfaction 8. Rhodopsin family members involved in vertebrate olfaction incl...

Ginkgo biloba L. leaf extracts and herbal infusions are used worldwide due to the health benefits that are attributed to its use, including anti-neoplastic, anti-aging, neuro-protection, antioxidant and others. The aim of this study was to evaluate the effect of an aqueous Ginkgo biloba extract on HepG2 cell viability, genotoxicity and DNA protection against paraquat-induced oxidative damage. Exposure to paraquat (PQ), over 24 h incubation at 1.0 and 1.5 µM, did not significantly reduce cell viability but induced concentration and time-dependent oxidative DNA damage. Ginkgo biloba leaf extract produced dose-dependent cytotoxicity (IC50 = 540.8 ± 40.5 µg/mL at 24 h exposure), and short incubations (1 h) produced basal and oxidative DNA damage (>750 and 1500 µg/mL, respectively). However, lower concentrations (e.g., 75 µg/mL) of Ginkgo biloba leaf extract were not cytotoxic and reduced basal DNA damage, indicating a protective effect at incubations up to 4 h. On the other hand, longer incubations (24 h) induced oxidative DNA damage. Co-incubation of HepG2 cells for 4 h, with G. biloba leaf extract (75 µg/mL) and PQ (1.0 or 1.5 µM) significantly reduced PQ-induced oxidative DNA damage. In conclusion, the consumption of Ginkgo biloba leaf extract for long periods at high doses/concentrations is potentially toxic; however, low doses protect the cells against basal oxidative damage and against environmentally derived toxicants that induce oxidative DNA damage.

Low temperatures provoke drastic reductions in gilthead sea bream (Sparus aurata) activity and nourishment, leading to growth arrest and a halt in production. However, scarce data exist concerning the implications of central core control during the cold season. The aim of this work was to study the effects of low temperature and recovery from such exposure on the pituitary activity of sea bream juveniles fed 18% or 14% dietary lipid. A controlled indoor trial was performed to simulate natural temperature fluctuation (22 °C to 14 °C to 22 °C). Meanwhile, we determined the regulatory role of the pituitary by analyzing the gene expression of some pituitary hormones and hormone receptors via qPCR, as well as plasma levels of thyroidal hormones. In response to higher dietary lipids, hormone pituitary expressions were up-regulated. Induced low temperatures and lower ingesta modulated pituitary function up-regulating GH and TSH and thyroid and glucocorticoid receptors. All these findings demonstrate the capacity of the pituitary to recognize both external conditions and to modulate its response accordingly. However, growth, peripheral tissues and metabolism were not linked or connected to pituitary function at low temperatures, which opens an interesting field of study to interpret the hypothalamus–pituitary–target axis during temperature fluctuations in fish.

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