Mutants of the Zebrafish K+ Channel Hcn2b Exhibit Epileptic-like Behaviors

In Search of a Target Gene for a Desirable Phenotype in Aquaculture: Genome Editing of Cyprinidae and Salmonidae Species

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout (Onchorhynchus mykiss), Atlantic salmon (Salmo salar), common carp (Cyprinus carpio), goldfish (Carassius auratus), Gibel carp (Carassius gibelio) and the model fish zebrafish (Danio rerio). Among the genes studied, the most applicable for aquaculture are mstnba, pomc, and acvr2, the knockout of which leads to enhanced muscle growth; runx2b, mutants of which do not form bones in myoseptae; lepr, whose lack of function makes fish fast-growing; fads2, Δ6abc/5Mt, and Δ6bcMt, affecting the composition of fatty acids in fish meat; dnd mettl3, and wnt4a, mutants of which are sterile; and disease-susceptibility genes prmt7, gab3, gcJAM-A, and cxcr3.2. Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use.

Toxicological and Sedative Effects of Chipilin (Crotalaria longirostrata) Leaf Extracts Obtained by Maceration and Supercritical Fluid Extraction

Chipilin (Crotalaria longirostrata) is consumed as a vegetable in the preparation of traditional dishes. As a folk medicine, Chipilin extracts are used as a hypnotic and sedative agent; however, there are few reports that support these uses. This study aimed to characterize the compounds present in Chipilin leaf extracts and to investigate their sedative effect using zebrafish as an in vivo model. Extracts were obtained by maceration with water (H2O), ethanol (EtOH), and EtOH-H2O, while oleoresin was obtained by supercritical fluid extraction (SFE). Total phenolic and flavonoid contents were quantified by colorimetric methods. Phytochemical constituents were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The chronic and acute toxicities of Chipilin extracts were tested in zebrafish embryos and larvae, respectively. Chipilin sedative effect was tested by the larvae response to dark-light-dark transitions. EtOH-H2O extracts had the highest value of total phenolics (5345 ± 5.1 μg GAE/g), followed by water and oleoresin (1815 ± 5.1 and 394 ± 5.1 μg GAE/g, respectively). In water extracts were identified the alkaloid trachelanthamidine, 1,2β-epoxy- and the alkyl ketone 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, while oleamide, α-monostearin, and erucamide were detected in all samples except in water extracts. Oleoresin extract had the lowest embryotoxicity (LC50 = 4.99 μg/mL) and the highest sedative effects. SFE is a green alternative to obtain Chipilin extracts rich in erucamide, an endocannabinoid analogue, which plays an important role in the development of the central nervous system and in modulating neurotransmitter release.

Effects of glyphosate-based herbicide on gametes fertilization and four developmental stages in Clarias gariepinus

Comparative toxicology continues to provide information on how the age of every living organism affects the frequency, severity, and nature of the potentially toxic agent. We investigated the effect of glyphosate-based herbicide (GBH) exposure on gametes and four developmental stages of Clarius gariepinus (C. gariepinus) (African Catfish). Gametes from healthy gravid female and mature male C. gariepinus were exposed to GBH in sublethal concentrations of 0.0 (G1, control), 0.02 (G2), 0.05 (G3), 0.1 (G4), 0.5 (G5), and 1.0 (G6) mg/L for 24 h at the standard conditions of temperature and water quality parameters. The surviving embryos were examined microscopically for malformation rate and edema occurrence post-GBH exposure. In a separate experiment; postfryer, fingerling, posfingerling and juvenile C. gariepinus were exposed to G1, G2, G3, G4, G5 and G6 of GBH concentrations daily consecutively for 28 days. Fish growth performance, behavioural changes, haematology, oxidative stress, and histology were assessed. From our results, GBH showed altered morphology 24 h post-fertilization, decreased body weight, growth parameters, behavioural indices, and survival rate in the various developmental stages. Oxidative stress metabolite, malondialdehyde levels, increases in the postfryer > postfingerlin > fingerling > juvenile C. gariepinus following GBH exposure. Leukopenia and thrombocytosis were observed in the postfingerlings and juvenile fish and decrease in the levels of reduced glutathione and activity of superoxide dismutase compared with the control. Histology showed gross necrosis of the fish gills, liver, brain, and cardiac myocytes in the exposed fish. Hence, our findings provide an insight into C. gariepinus developmental toxicity due to GBH, although continuous measurement of glyphosate levels in the fish and fish environment is essential.