Growth Of Zebrafish Research Articles

CRISPR/Cas9-induced asap1a and asap1b co-knockout mutant zebrafish displayed abnormal embryonic development and impaired neutrophil migration

ASAP1 (Arf-GAP with SH3 domain, the ankyrin repeat and the PH domain) is the GTPase activating protein of the small G protein Arf. To understand more about the physiological functions of ASAP1 in vivo, we chose to use the zebrafish as an animal model, and analyzed the characterization of asap1 using loss-of-function studies. Here, two isoforms in zebrafish, asap1a and asap1b, were found to be homologous to human ASAP1, and the gene knockout zebrafish lines for asap1a and asap1b were established using the CRISPR/Cas9 technique with different insertions and deletions of bases. Zebrafish with asap1a and asap1b co-knockout showed a significant reduction in survival and hatching rates, as well as an increase in malformation rates during the early stages of development, while the asap1a or asap1b single knockout mutants did not affect the growth and development of individual zebrafish. Exploring the gene expression compensation between asap1a and asap1b using qRT-PCR, we found that asap1b had increased expression when asap1a was knocked out, showing a clear compensatory effect against asap1a knockout; In turn, asap1a did not have detectable compensating expression after asap1b knockout. Furthermore, the co-knockout homozygous mutants displayed impaired neutrophil migration to Mycobacterium marinum infection, and showed an increased bacterial load. Together, these are the first inherited asap1a and/or asap1b mutant zebrafish lines by the CRISPR/Cas9 gene editing approach, and by serving as useful models, they can significantly contribute to better annotation and follow-up physiological studies of human ASAP1.

Functional characterization of stap2b in zebrafish vascular development.

The genetic control and signaling pathways of vascular development are not comprehensively understood. Transcription factors Islet2 (Isl2) and nr2f1b are critical for vascular growth in zebrafish, and further transcriptome analysis has revealed potential targets regulated by isl2/nr2f1b. In this study, we focused on the potential activation gene signal-transducing adaptor protein 2b (stap2b) and revealed a novel role of stap2b in vascular development. stap2b mRNA was expressed in developing vessels, suggesting stap2b plays a role in vascularization. Knocking down stap2b expression by morpholino injection or Crispr-Cas9-generated stap2b mutants caused vascular defects, suggesting a role played by stap2b in controlling the patterning of intersegmental vessels (ISVs) and the caudal vein plexus (CVP). The vessel abnormalities associated with stap2b deficiency were found to be due to dysregulated cell migration and proliferation. The decreased expression of vascular-specific markers in stap2b morphants was consistent with the vascular defects observed. In contrast, overexpression of stap2b enhanced the growth of ISVs and reversed the vessel defects in stap2b morphants. These data suggest that stap2b is necessary and sufficient to promote vascular development. Finally, we examined the interaction between stap2b and multiple signaling. We showed that stap2b regulated ISV growth through the JAK-STAT pathway. Moreover, we found that stap2b was regulated by Notch signaling to control ISV growth, and stap2b interacted with bone morphogenetic protein signaling to contribute to CVP formation. Altogether, we demonstrated that stap2b acts downstream of the isl2/nr2f1b pathway to play a pivotal role in vascular development via interaction with multiple signaling pathways.

Microplastics Pollution and Their Potential Impact in Marine Systems: A Case Study in Shandong Peninsula, China

Shandong Province is among China’s major marine provinces, and the marine environment in Shandong supports important economic activities, such as fishing, aquaculture, and tourism. The presence of microplastics in the marine environment can impact these activities and the livelihoods of people who depend on them. Therefore, studying microplastics in Shandong Peninsula is crucial for understanding and mitigating these impacts. In this research, the microplastics were detected with abundance ranging from 50.67 to 315.2 particles/kg dry weight, and polyethylene and polypropylene have dominant proportions in beach sand and sediments. Microplastics were also detected in holothurians and oysters with detection rates at 16.7% and 38.9%, respectively. This study highlighted that microplastics pollution in the Shandong Peninsula was closely related to anthropogenic activities. Moreover, microplastics have inhibited superoxide dismutase activity and significantly increased malondialdehyde during zebrafish growth, which provided a potential effect between microplastics and marine organism. Human activities contribute to microplastics pollution in the environment, while at the same time, the presence of microplastics can impact marine organism and human activities. To mitigate the impacts of microplastics on the Shandong Peninsula, it is important to reduce the sources of microplastics and to develop effective management strategies for controlling their spread and impact.

Tris(1,3-dichloro-2-propyl) phosphate causes female-biased growth inhibition in zebrafish: Linked with gut microbiota dysbiosis

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is ubiquitous in aquatic environment, but its effect on intestinal health of fish has yet not been investigated. In the present study, the AB strain zebrafish embryos were exposed to environmentally realistic concentrations (0, 30, 300, and 3000 ng·L−1) of TDCIPP for 90 days, after which the fish growth and physiological activities were evaluated, and the intestinal microbes were analyzed by 16S rRNA gene high-throughput sequencing. Our results manifested that the body length and body weight were significantly reduced in the female zebrafish but not in males. Further analyses revealed that TDCIPP resulted in notable histological injury of intestine, which was accompanied by impairment of epithelial barrier integrity (decreased tight junction protein 2), inflammation responses (increased interleukin 1β), and disruption of neurotransmission (increased serotonin) in female intestine. Male intestines maintained intact intestinal structure, and the remarkably increased activity of glutathione peroxidase (GPx) might protect the male zebrafish from inflammation and intestinal damage. Furthermore, 16S rRNA sequencing analysis showed that TDCIPP significantly altered the microbial communities in the intestine in a gender-specific manner, with a remarkable increase in alpha diversity of the gut microbiome in male zebrafish, which might be another mechanism for male fish to protect their intestines from damage by TDCIPP. Correlation analysis revealed that abnormal abundances of pathogenic bacteria (Chryseobacterium, Enterococcus, and Legionella) might be partially responsible for the impaired epithelial barrier integrity and inhibition in female zebrafish growth. Taken together, our study for the first time demonstrates the high susceptibility of intestinal health and gut microbiota of zebrafish to TDCIPP, especially for female zebrafish, which could be partially responsible for the female-biased growth inhibition.

Activation of Nrf2 by sulfuretin stimulates chondrocyte differentiation and increases bone lengths in zebrafish

Elongation of most bones occur at the growth plate through endochondral ossification in postnatal mammals. The maturation of chondrocyte is a crucial factor in longitudinal bone growth, which is regulated by a complex network of paracrine and endocrine signaling pathways. Here, we show that a phytochemical sulfuretin can stimulate hypertrophic chondrocyte differentiation in vitro and in vivo. We found that sulfuretin stabilized nuclear factor (erythroid-derived 2)-like 2 (Nrf2), stimulated its transcriptional activity, and induced expression of its target genes. Sulfuretin treatment resulted in an increase in body length of zebrafish larvae and induced the expression of chondrocyte markers. Consistently, a clinically available Nrf2 activator, dimethyl fumarate (DMF), induced the expression of hypertrophic chondrocyte markers and increased the body length of zebrafish. Importantly, we found that chondrocyte gene expression in cell culture and skeletal growth in zebrafish stimulated by sulfuretin were significantly abrogated by Nrf2 depletion, suggesting that such stimulatory effects of sulfuretin were dependent on Nrf2, at least in part. Taken together, these data show that sulfuretin has a potential use as supporting ingredients for enhancing bone growth.

Pomc knockout increases growth in zebrafish

Genome editing is a promising tool to accelerate the genetic improvement of important traits if the causative genes are known. In aquaculture, only a few causative genes for traits are known and used in genome editing. The pro-opiomelanocortin (pomc) gene is important for regulation of feeding behaviour, sexual dimorphism, growth, and pigmentation. However, it is unknown whether the knockout of this gene will have any adverse effects on other aquaculture production traits. In this study, pomc knockout zebrafish were employed to study the effects of pomc-knockout on survival, growth, feed conversion ratio (FCR), histology of tissues, and liver, as well as expression of genes related to fatty acid and cholesterol synthesis. Pomc−/− zebrafish increased body weight and decreased FCR when compared to WT and pomc+/− zebrafish. The histological analysis revealed that more skeletal muscle was produced in pomc-knockout zebrafish without observable obesity. Knockout of pomc had no effect on the histology of the brain and liver, as well as the survival rate. Expression of genes related to fatty acid and cholesterol synthesis suggests that pomc mutants reduce cholesterol level. These results indicate that pomc knockout increases growth performance and reduces FCR without side effects on other important traits in aquaculture. Therefore, pomc is a valuable gene for genetic modification using the Crispr/Cas9 system to improve growth and reduce FCR in aquaculture species.

Pyriproxyfen influences growth as well as thyroid hormone–related and gh/igf-1 gene expression during the early life stage of zebrafish (Danio rerio)

Pyriproxyfen is an agricultural chemical pesticide that has been detected in the aquatic environment. This study aimed to clarify the effects of pyriproxyfen on the growth as well as thyroid hormone– and growth-related gene expression of zebrafish (Danio rerio) during its early life stage. Pyriproxyfen exhibited a lethal effect in a concentration-dependent manner: the lowest and no effect concentrations were 250.7 and 111.7 μg/L, respectively. These concentrations were considerably higher than the residual environmental concentrations, indicating the low risk of this pesticide when present at such concentrations. In the zebrafish group treated with 56.6 μg/L pyriproxyfen, thyroid hormone receptor β gene expression levels remained unchanged, whereas thyroid-stimulating hormone β subunit, iodtyronin deiodinase 2, and thyroid hormone receptor α gene expression levels significantly decreased compared with the control group expression levels. In zebrafish treated with 111.7 or 250.7 μg/L pyriproxyfen, iodtyronin deiodinase 1 gene expression levels significantly increased. These results indicate that pyriproxyfen disrupts thyroid hormone activity in zebrafish. Furthermore, pyriproxyfen exposure inhibited zebrafish growth; consequently, we examined the expression of growth hormone (gh) and insulin-like growth factor-I (igf-1), which are important for growth. Pyriproxyfen exposure suppressed gh expression; however, the igf-1 expression levels remained unchanged. Therefore, growth inhibition due to pyriproxyfen exposure was attributed to the suppression of gh expression.

Effects of nuclease-treated fermentation product of Lactobacillus rhamnosus GCC-3 on growth, hepatic health and gut microbiota of zebrafish (Danio rerio) fed a high-fat diet

Probiotics are reported to improve the nutrition, immunity, and health of fish. Nuclease can hydrolyze nucleic acids of probiotics to produce nucleotides. The present study investigated the effect of stabilized fermentation product of nuclease-treated Lactobacillus rhamnosus GCC-3 (GCC-3 NT) on growth, non-specific immunity, liver health, and gut microbiota of zebrafish (Danio rerio). Compared to the high-fat diet (HFD) group, GCC-3 NT did not affect the growth performance of zebrafish. However, GCC-3 NT treatment can significantly increase the lysozyme activity and the total antioxidant capacity of body surface mucus. In addition, dietary GCC-3 NT significantly reduced the content of hepatic triglycerides (TAG) in zebrafish while significantly increased the expression of acyl-coenzyme A oxidases 3 (ACOX3) and proliferator-activated receptor γ coactivator 1α (PGC1α) compared with the HFD group. The 16S rRNA gene sequencing showed that GCC-3 NT reduced the relative abundance of Actinobacteria while increased Firmicutes at the phylum level. The relative abundance of Rhodococcus was significantly decreased and Lactobacillus and Staphylococcus abundance were significantly increased in the GCC-3 NT group compared to the HFD group. Furthermore, PCoA analysis showed GCC-3 NT diet had a significant effect on the autochthonous microbiota compared to the HFD diet. Together, our results showed that nuclease-treated L. rhamnosus fermentation product can improve the immunity, liver health and gut microbiota of zebrafish, suggesting that it can be potentially used as a functional feed additive for aquaculture.

Effect of long-term exposure to dyeing wastewater treatment plant effluent on growth and gut microbiota of adult zebrafish (Danio rerio).

Strict standards have been put forward for the treatment and discharge of dyeing wastewater worldwide. However, there are still traces amount of pollutants, especially emerging pollutants in dyeing wastewater treatment plant (DWTP) effluent. Few studies have focused on the chronic biological toxicity effect and mechanism of DWTP effluent. In this study, 3-month chronic compound toxic effects were investigated by the exposure of DWTP effluent using adult zebrafish. Significantly higher mortality and fatness and significantly lower body weight and body length were found in the treatment group. In addition, long-term exposure to DWTP effluent also obviously reduced liver-body weight ratio of zebrafish, causing abnormal liver development of zebrafish. Moreover, DWTP effluent led to obvious changes in the gut microbiota and microbial diversity of zebrafish. At phylum level, significantly higher of Verrucomicrobia but lower Tenericutes, Actinobacteria, and Chloroflexi were found in the control group. At genus level, the treatment group had significantly higher abundance of Lactobacillus, but significantly lower abundance of Akkermansia, Prevotella, Bacteroides, and Sutterella. These results suggested that long-term exposure to DWTP effluent led to imbalance of gut microbiota in zebrafish. In general, this research indicated that DWTP effluent pollutants could result in negative health outcomes to aquatic organisms.

AgRP Neuron-Specific Ablation Represses Appetite, Energy Intake, and Somatic Growth in Larval Zebrafish

Neuronal circuits regulating appetite are dominated by arcuate nucleus neurons, which include appetite-promoting and -suppressing neurons that release the orexigenic neuropeptide agouti-related protein (AgRP) and anorexigenic neuropeptide pro-opiomelanocortin, respectively, to compete for melanocortin receptors to modulate feeding behavior. In this study, we expressed novel agrp promoters, including different lengths of the 5' flanking regions of the agrp gene (4749 bp) in the zebrafish genome. We used the agrp promoter to derive the enhanced green fluorescent protein (EGFP)-nitroreductase (NTR) fusion protein, allowing expression of the green fluorescence signal in the AgRP neurons. Then, we treated the transgenic zebrafish AgRP4.7NTR (Tg [agrp-EGFP-NTR]) with metronidazole to ablate the AgRP neurons in the larvae stage and observed a decline in their appetite and growth. The expression of most orexigenic and growth hormone/insulin-like growth factor axis genes decreased, whereas that of several anorexigenic genes increased. Our findings demonstrate that AgRP is a critical regulator of neuronal signaling for zebrafish appetite and energy intake control. Thus, AgRP4.7NTR can be used as a drug-screening platform for therapeutic targets to treat human appetite disorders, including obesity. Furthermore, the unique agrp promoter we identified can be a powerful tool for research on AgRP neurons, especially AgRP neuron-mediated pathways in the hypothalamus, and appetite.

Effects of dietary nutmeg (Myristica fragrans) seed meals on growth, non-specific immune indices, antioxidant status, gene expression analysis, and cold stress tolerance in zebrafish (Danio rerio).

A medicinal plant, Myristica fragrans seed meal (nutmeg), was utilized to evaluate its impact on the growth, immunity, and antioxidant defense of zebrafish (Danio rerio). In this regard, zebrafish (0.47 ± 0.04 g) (mean ± S.D.) were fed with 0% (control), 1% (T1-nutmeg), 2% (T2-nutmeg), and 3% (T3-nutmeg) of powdered nutmeg for 70 days. At the end of the feeding trial, growth performance, survival rate of fish, and temperature-challenge effects were recorded. Immune and antioxidant parameters were also assessed through the collection of serum and skin mucus samples. The results indicated that nutmeg supplementation did not significantly influence the growth of zebrafish (P > 0.05); however, the survival rate of fish fed with 2 and 3% of nutmeg supplementation significantly decreased (P < 0.05). The skin mucus and serum total protein, total immunoglobulin (Ig), and lysozyme activity were significantly increased in T3-nutmeg treatment in comparison to the control (P < 0.05). Superoxide dismutase (SOD) and catalase (CAT) activities were also enhanced in the T3-nutmeg group (P < 0.05). Nutmeg supplementation significantly upregulated the mRNA expression of growth hormone (gh) and insulin growth factor-1 (igf-1). Moreover, the nutmeg inclusion upregulated the expression of interleukin-1β (IL-1β), lysozyme, sod, and cat. The dietary supplementation of nutmeg significantly increased the resistance of zebrafish against cold-water shock and survivability afterward (P < 0.05). In conclusion, the supplementation of 3% powdered nutmeg in zebrafish diets could be suggested as an effective immune stimulator that improves antioxidant defense and stress tolerance.

Combined toxicity of acetamiprid and cadmium to larval zebrafish (Danio rerio) based on metabolomic analysis

Emerging contaminants, such as neonicotinoid pesticide acetamiprid (Ace), are frequently detected in the water environment, which can interact with existing heavy metal cadmium (Cd) to produce unpredicted influence. Limited studies have evaluated the effects of multiple pollutant exposures on aquatic animals. Here, we characterized the joint toxicity of Ace and Cd exposure to zebrafish (Danio rerio). The results revealed that Cd and its combined exposure with Ace had an inhibitory effect on the growth of larval zebrafish and induced morphological defects. Combined exposure to high doses of Ace and Cd could significantly reduce the levels of TG, glucose, and pyruvate in larval zebrafish. Untargeted metabolomics revealed that Cd treatment (285) produced more differentially expressed metabolites (DEMs) than Ace treatment (115), and combined treatment produced the most DEMs (294). The KEGG pathway enrichment analysis showed that they could disrupt riboflavin metabolism, amino acid metabolism, and glycolipid metabolism in the larvae of D. rerio. ELISA showed that VB2, FMN, and FAD levels were significantly increased. In addition, gene expression analysis exhibited that the mRNA levels of essential genes related to glycolipid metabolism were substantially affected, such as PK, PEPckc, PPAR-α, and FABP6. Furthermore, targeted amino acid metabolomics confirmed that both single exposure to Cd and combined exposure to Ace and Cd altered the levels of amino acids in larvae, including ALA, ARG, MET, PRO, TYR, VAL, GLY, ORN, and PHE. Taken together, exposure to Ace and Cd, alone or in combination, exerted harmful effects on the individual development, riboflavin metabolism, glycolipid metabolism, and amino acid metabolism disorder of D. rerio. These findings highlighted that more attention should be paid to the compound toxicity of chemical mixtures to aquatic organisms.

Effect of live feed (Artemia Nauplii) and farm-made feed on growth and survival of Zebrafish, Danio rerio fry

Effect of live feed (Artemia Nauplii) and farm-made feed on growth and survival of Zebrafish, Danio rerio fry

Effect of Dietary Supplementation of Carrot Meal on Growth, Survival, WholeBody Composition and Total Carotenoid Content of Zebrafish, Danio rerio

Effect of Dietary Supplementation of Carrot Meal on Growth, Survival, WholeBody Composition and Total Carotenoid Content of Zebrafish, Danio rerio

Differential quantities of zinc oxide nanoparticles incorporated feed on growth and haematological characteristics of Zebrafish (Danio rerio)

Zinc oxide nanoparticles were synthesized and characterized using by UV-Visible Spectroscopy (UV-Vis); Scanning Electron Microscope (SEM); Energy Dispersive X–Ray Spectroscopy (EDAX); X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Six feeds were prepared by using the differential quantities of Zinc oxide nanoparticles such as 0;20; 40; 60; 80 and 100 mg along with a fish meal; groundnut oil cake; wheat flour and tapioca flour. Feed utilization and haematological parameters of zebrafish were estimated after 21 days. The UV-visible absorption spectra demonstrate that Zinc oxide Nanoparticles were measured in wavelengths within 200 to 300 nm. SEM image shows that the Zinc oxide nanoparticles were observed at the wavelength range from 8.40 mm. EDAX spectrum recorded two peaks located between t 0.2KeV and 8.6 KeV. XRD image shows that the diffraction peaks of Zinc oxide nanoparticles are indexed as 041;142; 123; 281; 163; and 100;200. FT-IR spectrum was observed at the wavelength range from 3512 - 1500 cm-1. The condition factor of Zebrafish was decreased in the final when compared to the initial. The feed consumption and feed conversion efficiency of Zebrafish were higher in feed V. The feed conversion ratio of Zebrafish was best in feed III. Growth and the percentage growth of Zebrafish were higher in feed VI. Assimilation and metabolism of Zebrafish were higher in feed V. Gross and Net growth efficiency were higher in feed III. All the haematological parameters increased with increased quantities of zinc oxide nanoparticles.

Effects of Emulsifier Material and Vegetable Oils on Zebrafish (Danio rerio) Growth Performance

This study was conducted to investigate the effects of Polyglycerol polyricinoleate, (PGPR; E-476) as a dietary emulsifier supplement with sunflower and linseed oil on zebrafish (Danio rerio) growth performance and feed utilization. The control diet included only fish oil whereas other experimental diets included 6% sunflower oil and linseed oil with and without PGPR at %0.06. A total of 180 zebrafish larvae were used in the experiment. At the end of the experiment, the whole body samples were taken for proximate and fatty acid analysis. The fish were fed diets that contained PGPR, S0%L0% (PGPR), S6%L0% (PGPR) and S0%L6% (PGPR), had higher values (p˂0.05) in final weight (557.1, 521.3 and 622 mg), weight gain (1982.83, 2129.5 and 2779.56%), specific growth rate (2.062, 2.099 and 2.272), digested lipids amount (127.23, 122.65 and 148.52 mg), feed conversion efficiency rate (1.683, 1.893 and 1.725), protein efficiency ratio (1.321, 1.181 and 1.31) and whole body lipid percentage (44.37, 37.9827 and 46.7063 %), respectively. The percentages of fatty acids in fish tissues that fed diet with PGPR diets, S0%L0% (PGPR), S6%L0% (PGPR) and S0%L6% (PGPR), were higher (p˂0.05); ΣSFAs (16.695, 12.732 and 14.672 %), ΣMFAs (17.748, 16.014 and 17.922%), and ΣPUFAs (9.926, 9.235 and 14.111%), respectively, which reflected a positive influence of the emulsifier on zootechnical performance variables. Briefly, the results suggest that dietary use of linseed oil with particularly PGPR appeared to be a better alternative to fish oil.

Aaqueous exposure to silver nanoparticles synthesized by abalone viscera hydrolysates promotes the growth, immunity and gut health of zebrafish (Danio rerio).

Silver nanoparticles (AgNPs) have the potential to be used in aquaculture, but their influence on the growth and health of aquatic organisms has not been extensively investigated. In this study, the abalone viscera hydrolysates decorated AgNPs (AVH-AgNPs) were dispersed into aquaculture water at different concentrations (0, 6, 9, and 18 μg/l) to evaluate the biological effects on zebrafish (Danio rerio). The results showed that the AVH-AgNPs treatments of 6 and 9 μg/l promoted the growth and did not cause obvious damage to the gills, intestines, and livers of zebrafish. All the treatments induced catalase (CAT) and superoxide dismutase (SOD) activities and increased glutathione (GSH) content in the livers and upregulated the expression of immune related genes. The effects of 9 and 18 μg/l AVH-AgNPs treatments were more obvious. After AVH-AgNPs treatment, the abundances of some potential pathogens, such as species Plesimonas shigelloides and Pseudomonas alcaligenes and genus Flavobacterium decreased significantly. In contrast, the abundance of some beneficial bacteria that can degrade pollutants and toxins (e.g., Rhodococcus erythropolis) increased significantly. Thus, the application of low concentrations (6 ~ 18 μg/l) of AVH-AgNPs in aquaculture water is relatively safe and has a positive effect on zebrafish farming.

Regular Supplementation with Antioxidants Rescues Doxorubicin-Induced Bone Deformities and Mineralization Delay in Zebrafish.

Osteoporosis is characterized by an abnormal bone structure with low bone mass and degradation of microarchitecture. Oxidative stress induces imbalances in osteoblast and osteoclast activity, leading to bone degradation, a primary cause of secondary osteoporosis. Doxorubicin (DOX) is a widely used chemotherapy drug for treating cancer, known to induce secondary osteoporosis. The mechanism underlying DOX-induced bone loss is still not fully understood, but one of the relevant mechanisms is through a massive accumulation of reactive oxygen and nitrogen species (i.e., ROS and NOS) leading to oxidative stress. We investigated the effects of antioxidants Resveratrol and MitoTEMPO on DOX-induced bone impairment using the zebrafish model. DOX was shown to increase mortality, promote skeletal deformities, induce alterations on intestinal villi, impair growth and mineralization and significantly downregulate osteoblast differentiation markers osteocalcin 2 and osterix/sp7. Lipid peroxidation was significantly increased in DOX-supplemented groups as compared to control and antioxidants, suggesting ROS formation as one of the key factors for DOX-induced bone loss. Furthermore, DOX affected mineral contents, suggesting an altered mineral metabolism. However, upon supplementation with antioxidants, DOX-induced effects on mineral content were rescued. Our data show that supplementation with antioxidants effectively improves the overall growth and mineralization in zebrafish and counteracts DOX-induced bone anomalies.

Toxic effects of combined exposure of tritiated water and genistein on the growth and development of zebrafish and its mechanism

Water pollution and control are important issues of our lasting concern. Environmental media often contains a variety of compounds. Tritium is widely present in nature due to human activities. As an endocrine disruptor, genistein is widely found in water body. Will it cause damage when combined with tritiated water and genistein? In this study, Zebrafish embryos were randomly divided into 4 groups: blank control group (simple E3 medium), tritiated water exposure group (tritiated water with a final concentration of 3.7*102Bq/mL in the medium), and genistein exposure group (the final concentration of 1.4 mg/L genistein in the medium) and the combined exposure group of tritiated water and genistein (3.7*102 Bq/mL tritium water +1.4 mg/L genistein). The results show that tritiated water with 3.7*102 Bq/ml exposure alone did not affect the development of zebrafish embryos. However, the survival rate, hatching rate and heart rate of zebrafish larvae decreased combined exposure with genistein, and the abnormality rate and apoptotic cells in the embryos and the level of oxidative stress increased. The results of RNA sequencing showed that the combined exposure of tritiated water and genistein affected the gene expression of zebrafish embryos. Differential genes were mainly enriched in many pathways, such as p53 signaling pathway, steroid hormone biosynthesis, PPAR signaling pathway, metabolism of xenobiotics by cytochrome P450. The results of qRT-PCR and gene knockout experiment showed that cyp19a1b gene may plays an important role in the toxic effects of combined exposure.

Agouti overexpression in a transgenic model regulates integrity, permeability and electrogenic amino acid transport in zebrafish intestine

Overexpression of asip1 in transgenic zebrafish disrupts dorsoventral pigment pattern in addition to increasing food intake levels and linear growth. A higher feed intake is unnecessary in transgenic fish to enable larger and heavier growth. A plausible explanation may rely on the enhanced feeding efficiency mediated by improved nutrient absorption in transgenic animals. To test this hypothesis, wide scope transcriptomic techniques were used to elucidate the potential pathways involved in the enhanced nutrient absorption and intestinal epithelium permeability/integrity. In addition, the electrogenic capacity for amino acid transport was analysed. Transcriptomic analysis reveal that amino acid, monocarboxylates, ionic and vitamin transmembrane transporters were substantially modified. Enrichment analysis also revealed an inhibition of intestinal lipid metabolism and down-regulation of KEGG pathways related to membrane integrity suggesting augmented intestinal laxity that may enhance paracellular transport. Electrophysiological experiments carried out in Ussing chambers show that asip1 overexpression decrease membraned tissue resistance (Rt), indicating a modification of the intestinal barrier function in ASIP1 transgenic animals. Similarly, paracellular permeability was higher in transgenic zebrafish. Both the decrease in Rt and the increase in permeability point to an ASIP1-dependent decrease in the tissue barrier function. Electrogenic amino acid transport was also enhanced in transgenic animals providing strong indication that ASIP1 fish can extract more amino acids from their diet at similar feeding levels. Both transcriptomic and electrophysiological results suggest that asip1-overexpressing zebrafish display improved nutrient absorption and by extension a higher feed efficiency which explains enhanced growth in the absence of augmented food intake. The enhanced growth of ASIP1 zebrafish potentially mediated by improved nutrient uptake and feed efficiency suggests that the melanocortin system, specifically asip1 overexpression, is a potential target for the development of genetically engineered fish displaying improved performance and no differential lipid accumulation.