Differential Nervous Necrosis Virus (NNV) Replication in Five Putative Susceptible Cell Lines

Viral encephalopathy and retinopathy caused by nervous necrosis virus (NNV), is one of the most threatening viral diseases affecting marine fish worldwide. In vitro propagation of NNV strains is essential for the design of effective control measures. In the present study we analysed both the susceptibility and the permissiveness of five fish cell lines (E-11, GF-1, SAF-1, DLB-1, and SaB-1) to three NNV strains (one RGNNV, one SJNNV, and one reassortant RGNNV/SJNNV). E-11 and DLB-1 were demonstrated to be highly susceptible to NNV strains, with average adsorption efficiency (AE) values higher than 90%. SAF-1 also showed high susceptibility (AE 88%), whereas GF-1 can be regarded as moderately susceptible (AE around 50%). On the contrary, SaB-1 can be considered a poorly susceptible cell line (AE values below 20%). E-11 and GF-1 cell lines provided the highest production rates for RGNNV and RG/SJ (around 103) and both cell lines can be regarded as fully permissive for these viral types. However, the SJNNV production rate in GF-1 was only 17.8 and therefore this cell line should be considered semi-permissive for this genotype. In SAF-1 cells, moderate viral replication was recorded but differences in intracellular and extracellular production suggest that viral progeny was not efficiently released. In DLB-1 and SaB-1 the final viral titres obtained in E-11 were lower than those of the inoculum. However, RNA1 synthesis values seem to indicate that RGNNV replication in DLB-1 and SAF-1 could have been underestimated, probably due to a poor adaptation of the virus grown in these cell lines to E-11. Based on all these results, E-11 seems to be the most appropriate cell for in vitro culture of RGNNV, SJNNV, and reassortant strains.

Mechanisms of Silver Nanoparticle Uptake by Embryonic Zebrafish Cells

Evaluation of the uptake pathways in cells during exposure to nanoparticles (NPs) is key for risk assessment and the development of safer nanomaterials, as the internalisation and fate of NPs is linked to their toxicity and mode of action. Here, we determined the uptake mechanisms activated during the internalisation of 10, 30, and 100 nm AgNPs by embryonic zebrafish cells (ZF4). The uptake results demonstrated an NP size- and time-dependent uptake, showing the highest total silver uptake for the smallest AgNP (10 nm) at the lowest exposure concentration (2.5 μg/mL) after 2 h, while after 24 h, the highest exposure concentration (10 μg/mL) of the 10 nm AgNPs revealed the highest cellular load at 8 pg/cell. Inhibition of the caveolae, clathrin, and macropinocytosis endocytic pathways by pharmaceutical inhibitors (genistein, chlorpromazine, and wortmannin respectively) revealed that uptake was mainly via macropinocytosis for the 10 nm AgNPs and via the caveolae-mediated pathway for the 30 and 100 nm AgNPs. The induction of autophagy was also strongly related to the NP size, showing the highest percentage of induction for the 10 nm (around 3%) compared to naive cells, suggesting that autophagy can be activated along with endocytosis to deal with exposure to NPs. TEM imaging revealed the distribution of NPs across the cytoplasm inside intracellular vesicles. An increase in Early Endosome formation (EE) was observed for the 30 and 100 nm sizes, whereas the 10 nm AgNPs disrupted the activity of EE. The data supports the establishment of adverse outcome pathways by increasing knowledge on the link between a molecular initiating event such as receptor-mediated endocytosis and an adverse outcome, as well as supporting the reduction of animal testing by using alternative testing models, such as fish cell lines.

Cytotoxicity of Mycotoxins Frequently Present in Aquafeeds to the Fish Cell Line RTGill-W1

In the last decades, the aquaculture industry has introduced plant-based ingredients as a source of protein in aquafeeds. This has led to mycotoxin contaminations, representing an ecological, health and economic problem. The aim of this study was to determine in the RTgill-W1 fish cell line the toxicity of fifteen mycotoxins of common occurrence in aquafeeds. To identify the most sensitive endpoint of toxicity, the triple assay was used. It consisted of three assays: alamarBlue, Neutral Red Uptake and CFDA-AM, which revealed the mitochondrial activity, the lysosomal integrity and the plasma membrane integrity, respectively. Most of the assayed mycotoxins were toxic predominantly at lysosomal level (enniatins, beauvericin, zearalenone, ochratoxin A, deoxynivalenol (DON) and its acetylated metabolites 15-O-acetyl-DON and 3-acetyl-DON). Aflatoxins B1 and B2 exerted the greatest effects at mitochondrial level, while fumonisins B1 and B2 and nivalenol were not toxic up to 100 µg/mL. In general, low toxicity was observed at plasma membrane level. The vast majority of the mycotoxins assayed exerted a pronounced acute effect in the fish RTgill-W1 cell line, emphasizing the need for further studies to ascertain the impact of mycotoxin contamination of fish feeds in the aquaculture industry and to establish safe limits in aquafeeds.

LncRNA JPX Promotes Esophageal Squamous Cell Carcinoma Progression by Targeting miR-516b-5p/VEGFA Axis

Background: Long non-coding RNAs (lncRNAs) are reported act as important regulators in various cancers. LncRNA JPX was identified as an oncogenic regulator in lung cancer. However, the function of lncRNA JPX in the progression of esophageal squamous cell carcinoma (ESCC) remains unclear. Methods: The effects and molecular mechanism of JPX on the progression of ESCC were investigated using fluorescence in situ hybridization (FISH), cell proliferation, quantitative real-time PCR (qRT-PCR), western blot, dual luciferase, cell cycle, 5-Ethynyl-2′-Deoxyuridine (EdU) incorporation, transwell, RNA pull-down, tube formation and RNA immunoprecipitation (RIP) assays. Results: In the present study, we found JPX was highly expressed in tissues of ESCC patients and different ESCC cell lines. Functional assays demonstrated that JPX promoted ESCC cell proliferation, migration and invasion in vitro and tumor growth in vivo. Moreover, we found JPX promoted ESCC mobility in vitro. Mechanistically, the results showed that JPX functions as a sponge of miR-516b-5p, which targets an oncogene vascular endothelial growth factor A (VEGFA) in ESCC cells. Interactions between miR-516b-5p and JPX or VEGFA were confirmed by luciferase reporter assays. Furthermore, inhibition of JPX significantly attenuated the cell growth and mobility ability of ESCC cells in vitro. In addition, miR-516b-5p overexpression abrogated JPX enhanced proliferation, migration, invasion, and angiogenesis of ESCC cells. Conclusions: Our study demonstrated that JPX played an important role in promoting ESCC progression via the miR-516b-5p/VEGFA pathway and might serve as a promising novel therapeutic target for ESCC patients.

Effect of Giving Different Doses of Vitamin E in Feed to the Level of Gonad Maturity of Tilapia (Oreochromis niloticus)

One of the nutrients that can be given to brood feed fish to improve reproductive performance and egg quality is vitamin E. Vitamin E has a very important role in increasing fish reproduction because vitamin E functions as an antioxidant that can maintain the presence of fatty acids and prevent fat oxidation in the fish cell membrane and can accelerate the secretion of reproductive hormones. This study aims to determine the effect of vitamin E in feed at different doses on the level of gonad maturity of tilapia. The research was conducted at the Fisheries Laboratory of the Faculty of Marine and Fisheries, Udayana University from July to August 2020. The samples of fish tested were tilapia (Oreochromis niloticus) obtained from the Teratai fishing pond, Sanur Bali. Vitamin E used was Ovagrow Vit E with a vitamin E content of 50%. The CRD method (completely randomized design) was used with four treatments and three replications. The doses of vitamin E that were mixed into the feed were 0, 100, 300, and 500 mg/kg of feed. The results showed that the administration of vitamin E mixed in the feed at different doses had a significant effect on the achievement of gonad maturity level, gonad somatic index (GSI), and Fecundity (P <0.05). Provision of vitamin E at a dose of 300 mg/kg of feed was the best dose for ripening tilapia gonads. The gonad maturity level developed up to maturity stage IV, the GSI value was (3.56 ± 0.46) and the fecundity value was (1379 ± 289).