Combined effect of anthracene and polyethylene microplastics on swimming speed and cytochrome P4501A monooxygenase expression of Java medaka (Oryzias javanicus)

Microplastics have been detected in a variety of aquatic ecosystems, and the combined effect of microplastics and chemical pollutants has become a matter of increasing concern. We conducted a 12-d co-exposure test of anthracene and spherical or fragmented polyethylene microplastics (size 200 µm) on Java medaka (Oryzias javanicus). The accumulation of anthracene in Java medaka muscle reached a plateau on day 5 in all anthracene exposure groups, and no significant differences were detected among the groups (ANT, 20.4 ± 5.5; ANT + SPPE-MP, 24.7 ± 2.7; ANT + FRPE-MP, 24.6 ± 4.7 µg/g). However, co-exposure to anthracene and spherical or fragmented polyethylene microplastics increased the duration of slow swimming in a swimming behavior test (control, 4.1 ± 1.4; ANT, 5.2 ± 2.8; ANT + SPPE-MP, 12.4 ± 3.7; ANT + FRPE-MP, 17.4 ± 5.1 min/30 min), and co-exposure to anthracene and fragmented polyethylene microplastics induced higher cytochrome P4501A monooxygenase (CYP1A) expression in Java medaka livers than the other anthracene exposure groups (ANT, 189 ± 74; ANT + SPPE-MP, 203 ± 75; ANT + FRPE-MP 272 ± 36% of control). Polyethylene microplastics appear to be weak vectors of anthracene at the size tested (200 µm), and the effect of shape (spherical or fragmented) on the vector effect was small. However, the presence of polyethylene microplastics could affect the swimming behavior and CYP1A expression in Java medaka.

Deep ocean water alters the cholesterol and mineral metabolism of squid Todarodes pacificus and suppresses its weight loss

This study is the first to demonstrate that deep ocean water (DOW) has physiological significant effects on squid. After 36 h of rearing squids, those reared with DOW had significantly higher total and free cholesterol levels and lower alanine transaminase activity in hemolymph as compared with those reared with surface sea water (SSW). SSW rearing also resulted in 6.95% weight loss, while DOW rearing caused only 2.5% weight loss, which might be due to liver metabolism suppression. Furthermore, both monovalent (sodium, chloride, and potassium ions) and divalent (calcium, inorganic phosphorus, and magnesium ions) ions in hemolymph were elevated when reared with DOW compared to those when reared with SSW. A study of genes expressed in the brain revealed that five genes were specifically remarked in DOW rearing. Most altered genes were neuropeptides, including those from vasopressin superfamily. These neuropeptides are involved in cholesterol and/or mineral metabolisms and physiological significant effects on squid. This study is the first report the effects of DOW on cholesterol and mineral metabolism of squid and will contribute to squid aquaculture using DOW.