Plastic microfibers (MF) represent the major source of MF found in the environment, the majority made of polyester (PES). Marine bivalves, suspension feeders widespread in coastal areas subjected to higher anthropogenic input, can accumulate MF from the water column in their tissues. This raised some concern about their possible impact on bivalve health and potential transfer along the food chain. In this work, the effects of PES-MF on the mussel Mytilus galloprovincialis were investigated, utilizing MF obtained by cryo-milling of a fleece cover. Fiber characterization indicated the polymer composition as polyethylene terephthalate (PET); the size distribution was in a length range resembling that of MF released from textile washing, and including those that can be ingested by mussels. MF were first screened for short-term in vitro immune responses in mussel hemocytes. The effects of in vivo exposure (96 h, 10 and 100 μg/L, corresponding to about 150 and 1500 MF/mussel/L, respectively), were then evaluated. Data are presented on hemolymph immune biomarkers (Reactive Oxygen Species and nitric oxide production, lysozyme activity), and on antioxidant biomarkers (catalase and glutathione S-transferase) and histopathology in gills and digestive gland. Tissue MF accumulation was also evaluated. MF exposure stimulated extracellular immune responses both in vitro and in vivo, indicating induction of immune/inflammatory processes. In both tissues, stimulation of antioxidant enzyme activities, suggesting oxidative stress conditions, and histopathological changes were observed, with stronger effects often observed at lower concentration. Although mussel retained a very small fraction of MF, their accumulation was higher in the digestive gland than in gills, and in both tissues of mussels exposed to the lowest concentration. Selective accumulation of shorter MF was also observed, particularly in gills. Overall, the results demonstrate that at environmental exposure levels, PET-MF have a significant impact on mussel physiology, affecting multiple processes in different tissues.

The broadly utilized biocide triclosan (TCS) is continuously discharged in water compartments worldwide, where it is detected at concentrations of ng-µg/L. Given its lipophilicity and bioaccumulation, TCS is considered potentially harmful to human and environmental health and also as a potential endocrine disruptor (ED) in different species. In aquatic organisms, TCS can induce a variety of effects: however, little information is available on its possible impact on invertebrate development. Early larval stages of the marine bivalve Mytilus galloprovincialis have been shown to be sensitive to environmental concentrations of a number of emerging contaminants, including EDs. In this work, the effects of TCS were first evaluated in the 48 h larval assay in a wide concentration range (0.001–1,000 μg/L). TCS significantly affected normal development of D-veligers (LOEC = 0.1 μg/L; EC₅₀ = 236.1 μg/L). At selected concentrations, the mechanism of action of TCS was investigated. TCS modulated transcription of different genes involved in shell mineralization, endocrine signaling, ceramide metabolism, and biotransformation, depending on larval stage (24 and 48 h post-fertilization-hpf) and concentration (1 and 10 μg/L). At 48 hpf and 10 μg/L TCS, calcein staining revealed alterations in CaCO₃ deposition, and polarized light microscopy showed the absence of shell birefringence due to the mineralized phase. Observations by scanning electron microscopy highlighted a variety of defects in shell formation from concentrations as low as 0.1 μg/L. The results indicate that TCS, at environmental exposure levels, can act as a developmental disruptor in early mussel larvae mainly by interfering with the processes of biomineralization.

Brain somatic variants in the SLC35A2 gene, encoding for a Golgi galactose transporter, represent the major cause of mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). Clinical features associated with MOGHE include early-onset epileptic encephalopathy, drug-resistant focal epilepsy with developmental delay, and intellectual disability. Half of somatic SLC35A2 variants identified in MOGHE patients are predicted to encode full-length SLC35A2 protein or stable protein products. We investigated the pathophysiological basis of MOGHE by analyzing the functional consequences of SLC35A2 pathogenetic variants in vitro and in vivo models. We assessed how different SLC35A2 variants impact protein stability and expression in transfected cellular models. We used in utero electroporation in the rat brain to model mosaic expression of SLC35A2 pathogenetic variants in the cerebral cortex and assessed their effect on neurons migration and morphology. We found that SLC35A2 variants identified in MOGHE patients variably impact on SLC35A2 protein expression. In utero expression of a SLC35A2 missense (p.G282A) or frameshift (p.F280Tfs*10) variants resulted in neuronal heterotopia in the white matter and impaired dendritogenesis at postnatal stages, suggesting a cell autonomous role for SLC35A2 in neuronal development. These phenotypes were recapitulated by in utero silencing of rat Slc35a2 gene. We successfully developed an in vivo mosaic model for the characterization of SLC35A2 variants identified in MOGHE patients and demonstrated that the expression of single SLC35A2 variants triggers the pathophysiological cascade associated with SLC35A2 dysfunction in neurons.

The olfactory system is constituted in a consistent way across vertebrates. Nasal structures allow water/air to enter an olfactory cavity, conveying the odorants to a sensory surface. There, the olfactory neurons form, with their axons, a sensory nerve projecting to the telencephalic zone—named the olfactory bulb. This organization comes with many different arrangements, whose meaning is still a matter of debate. A morphological description of the olfactory system of many teleost species is present in the literature; nevertheless, morphological investigations rarely provide a quantitative approach that would help to provide a deeper understanding of the structures where sensory and elaborating events happen. In this study, the peripheral olfactory system of the Antarctic silverfish, which is a keystone species in coastal Antarctica ecosystems, has also been described, employing some quantitative methods. The olfactory chamber of this species is connected to accessory nasal sacs, which probably aid water movements in the chamber; thus, the head of the Antarctic silverfish is specialized to assure that the olfactory organ keeps in contact with a large volume of water—even when the fish is not actively swimming. Each olfactory organ, shaped like an asymmetric rosette, has, in adult fish, a sensory surface area of about 25 mm², while each olfactory bulb contains about 100,000 neurons. The sensory surface area and the number of neurons in the primary olfactory brain region show that this fish invests energy in the detection and elaboration of olfactory signals and allow comparisons among different species. The mouse, for example—which is considered a macrosmatic vertebrate—has a sensory surface area of the same order of magnitude as that of the Antarctic silverfish, but ten times more neurons in the olfactory bulb. Catsharks, on the other hand, have a sensory surface area that is two orders of magnitude higher than that of the Antarctic silverfish, while the number of neurons has the same order of magnitude. The Antarctic silverfish is therefore likely to rely considerably on olfaction.

SLC35A2 encodes the Golgi uridine diphosphate galactose transporter, which is essential for glycosylation of glycoproteins and glycolipids. Variants in this gene, either germline or somatic, have emerged as causes of diverse neurological disorders ranging from congenital disorders of glycosylation (SLC35A2-CDG) to focal cortical malformations such as mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). This review summarizes the molecular function of SLC35A2, clinical phenotypes of congenital and somatic variants, insights from functional assays and animal models, and therapeutic perspectives including galactose supplementation and precision medicine. We aim to provide an integrative synthesis of human genetics, neuropathology, glycomics, and translational approaches.