Probiotic expressing heterologous phytase improves the immune system and attenuates inflammatory response in zebrafish fed with a diet rich in soybean meal.

Although aquaculture is among the fastest growing food production sectors in the world, one of the bottlenecks for the continuity of its expansion is the dependence of animal protein on commercial feed formulations. Vegetable proteins are an alternative due to the low cost and high availability. However, this protein source is accompanied by a series of antinutritional and pro-inflammatory compounds, including phytate. Phytases can be added in feed for phytate degradation and increase nutrient availability. However, the use of purified phytases significantly increases the production costs. An interesting alternative is to use probiotics genetically modified as bioreactors for phytase production. In the present study, a strain of Bacillus subtilis secreting a fungal phytase was used to evaluate the effect of a feed with high content of soybean meal on zebrafish (Danio rerio). We analysed the condition factor (K) of fish, and the expression of genes related to the immune system, inflammatory response and oxidative. stress. The results obtained demonstrate that the transgenic probiotic was efficient in improving the fish condition factor, stimulating the immune system, reducing the inflammatory response and oxidative stress. Thus, probiotics acting as phytase bioreactors can be considered an interesting tool for the adaptation of commercial species to feed of lower cost.

Reproductive parameters of double transgenic zebrafish (Danio rerio) males overexpressing both the growth hormone (GH) and its receptor (GHR).

Growth hormone (GH) transgenesis presents a high potential application in aquaculture. However, excess GH may have serious consequences due to pleiotropic actions. In order to study these effects in zebrafish (Danio rerio), two transgenic lines were developed. The first expresses GH ubiquitously and constitutively (F0104 line), while the second expresses the GH receptor in a muscle-specific manner (Myo-GHR line). Results from the F0104 line showed accelerated growth but increased reproductive difficulties, while Myo-GHR did not show the expected increase in muscle mass. Since the two lines appeared to display complementary characteristics, a double transgenic (GH/GHR) was created via crossing between them. This double transgenic displayed accelerated growth, however reproductive parameters remained uncertain. The objective of the present study was to determine the reproductive capacity of males of this new line, by evaluating sperm parameters, expression of spermatogenesis-related genes, and reproductive tests. Double transgenics showed a strong recovery in almost all sperm parameters analyzed when compared to the F0104 line. Gene expression analyses revealed that Anti-Müllerian Hormone gene (amh) appeared to be primarily responsible for this recovery. Reproductive tests showed that double transgenic males did not differ from non-transgenics. It is possible that GHR excess in the muscle tissues of double transgenics may have contributed to lower circulating GH levels and thus reduced the negative effects of this hormone with respect to reproduction. Therefore, it is clear that GH-transgenesis technology should take into account the need to obtain adequate levels of circulating hormone in order to achieve maximum growth with minimal negative side effects.

GH indirectly enhances the regeneration of transgenic zebrafish fins through IGF2a and IGF2b.

The somatotropic axis, composed essentially of the growth hormone (GH) and insulin-like growth factors (IGFs), is the main regulator of somatic growth in vertebrates. However, these protein hormones are also involved in various other major physiological processes. Although the importance of IGFs in mechanisms involving tissue regeneration has already been established, little is known regarding the direct effects of GH in these processes. In this study, we used a transgenic zebrafish (Danio rerio) model, which overexpresses GH from the beta-actin constitutive promoter. The regenerative ability of the caudal fin was assessed after repeated amputations, as well as the expression of genes related to the GH/IGF axis. The results revealed that GH overexpression increased the regenerated area of the caudal fin in transgenic fish after the second amputation. Transgenic fish also presented a decrease in gene expression of the GH receptor (ghrb), in opposition to the increased expression of the IGF1 receptors (igf1ra and igf1rb). These results suggest that transgenic fish have a higher sensitivity to IGFs than to GH during fin regeneration. With respect to the different IGFs produced locally, a decrease in igf1a expression and a significant increase in both igf2a and igf2b expression was observed, suggesting that igf1a is not directly involved in fin regeneration. Overall, the results revealed that excess GH enhances fin regeneration in zebrafish through igf2a and igf2b expression, acting indirectly on this major physiological process.

Expression profile of IGF paralog genes in liver and muscle of a GH-transgenic zebrafish.

The objective of this study was to investigate the relationship between IGFs produced in the liver and skeletal muscle with muscle hypertrophy previously observed in a line of GH-transgenic zebrafish. In this sense, we evaluated the expression of genes related to the IGF system in liver and muscle of transgenics, as well as the main intracellular signaling pathways used by GH/IGF axis. Our results showed an increase in expression of igf1a, igf2a, and igf2b genes in the liver. Moreover, there was a decrease in the expression of igf1ra and an increase in muscle igf2r of transgenics, indicating a negative response of muscle tissue with respect to excess circulating IGFs. Muscle IGFs expression analyses revealed a significant increase only for igf2b, accompanied by a parallel induction of igfbp5a gene. The presence of IGFBP5a may potentiate the IGF2 action in muscle cells differentiation. Regarding JAK/STAT-related genes, we observed an alteration in the expression profile of both stat3 and stat5a in transgenic fish liver. No changes were observed in the muscle, suggesting that both tissues respond differently to GH-transgenesis. Western blotting analyses indicated an imbalance between the phosphorylation levels of the proliferative (MEK/ERK) and hypertrophic (PI3K/Akt) pathways, in favor of the latter. In summary, the results of this study suggest that the hypertrophy caused by GH-transgenesis in zebrafish may be due to circulating IGFs produced by the liver, with an important participation of muscle IGF2b. This group of IGFs appears to be favoring the hypertrophic intracellular pathway in muscle tissue of transgenic zebrafish.

Induction of phase II enzymes and hsp70 genes by copper sulfate through the electrophile-responsive element (EpRE): insights obtained from a transgenic zebrafish model carrying an orthologous EpRE sequence of mammalian origin.

We have evaluated the homology of the electrophile-responsive element (EpRE) core sequence, a binding site for the Nrf2 transcription factor, in the proximal promoters of the mouse and zebrafish glutathione-S-transferase (gst), glutamate cysteine ligase catalytic subunit (gclc) and heat shock protein 70 (hsp70) genes. The EpRE sites identified for both species in the three analyzed genes showed a high similarity with the putative EpRE core sequence. We also produced a transgenic zebrafish model carrying a transgene comprised of the luciferase (luc) reporter gene under transcriptional control of a mouse EpRE sequence. This transgenic model was exposed to copper sulfate, and the reporter gene was significantly activated. The endogenous gst, gclc and hsp70 zebrafish genes were analyzed in the EpRE-Luc transgenic zebrafish and showed an expression pattern similar to that of the reporter transgene used. Our results demonstrate that EpRE is conserved between mouse and zebrafish for detoxification-related genes and that the development of genetically modified models using this responsive element to drive the expression of reporter genes can be an important tool in understanding the action mechanism of aquatic pollutants.

Zebrafish (Danio rerio) ability to activate ABCC transporters after exposure to glyphosate and its formulation Roundup Transorb®.

The emergent demand for food production has increased the widespread use of pesticides, especially glyphosate-based herbicides as they can protect different types of crops, especially transgenic ones. Molecules of glyphosate have been found in water bodies around the world, and its presence can cause negative effects on non-target organisms, such as fish. Glyphosate toxicity appears to be systemic in fish but does not affect their organs equally. Also, its formulations can be more toxic than pure glyphosate. In this sense, we investigated if these variations in toxicity could be related to ATP binding cassette subfamily C (ABCC) transporters and the cellular detoxification capacity, following exposure to herbicides. Thus, adults of Danio rerio were exposed (24 and 96 h) to glyphosate and Roundup Transorb® (RT) at an environmental concentration of 0.1 mg/L, and the activity of ABCC proteins and gene expression of five isoforms of ABCC were analyzed. Glyphosate and RT exposure increased ABCC protein activity and gene expression up to 3-fold when compared to controls, indicating the activation of detoxification mechanisms. Only in the brain of D. rerio, the exposure to RT did not stimulate the activity of ABCC proteins, neither the expression of genes abcc1 and abcc4 that responded to the exposure to pure glyphosate. These results may suggest that the brain is more sensitive to RT than the other target-tissues since the mechanism of detoxification via ABCC transporters were not activated in this tissue as it was in the other.

Modeling drug-drug interactions of AZD1208 with Vincristine and Daunorubicin on ligand-extrusion binding TMD-domains of multidrug resistance P-glycoprotein (ABCB1).

In the present study, the molecular docking mechanism based on pharmacodynamic interactions between the ligands AZD1208 and recognized chemotherapy agents (Vincristine and Daunorubicin) with human ATP-binding cassette (ABC) transporters (ABCB1) was investigated. For the first time, were combined an in silico approaches like molecular docking and ab initio computational simulation based on Density Functional Theory (DFT) to explain the drug-drug interaction mechanism of aforementioned chemotherapy ligands with the transmembrane ligand extrusion binding domains (TMDs) of ABCB1. In this regard, the theoretical pharmacodynamic interactions were characterized by using the Gibbs free energy (FEB, kcal/mol) from the best ABCB1-ligand docking complexes. The molecular docking results pointing that for the three chemotherapy ABCB1-ligand complexes are mainly based in non-covalent hydrophobic and hydrogen-bond interactions showing a similar toxicodynamic behavior in terms of strength of interaction (FEB, kcal/mol) and very close free binding energies when compared with the FEB-values of the ABCB1 specific-inhibitor (Rhodamine B) = -6.0 kcal/mol used as theoretical docking control to compare with FEB (AZD1208-ABCB1) ∼ FEB (Vincristine-ABCB1) ∼ FEB (Daunorubicin-ABCB1) -6.2 kcal/mol as average. Ramachandran plot suggests that the 3D-crystallographic structure from ABCB1 transporter can be efficiently-modeled with conformationally-favored Psi versus Phi dihedral angles for all key TMDs-residues. Though, the results of DFT-simulation corroborate the existence of drug-drug interaction between (AZD1208/Vincristine) > (AZD1208/Daunorubicin). These theoretical pieces of evidence have preclinical relevance potential in the design of the new drugs to understand the polypharmacology influence in the molecular mechanism of multiple-drugs resistance, contributing with a higher success in chemotherapy and prognosis of cancer patients.

New Mechanistic Insight on the PIM-1 Kinase Inhibitor AZD1208 Using Multidrug Resistant Human Erythroleukemia Cell Lines and Molecular Docking Simulations.

BACKGROUND: PIM-1 is a kinase which has been related to the oncogenic processes like cell survival, proliferation, and multidrug resistance (MDR). This kinase is known for its ability to phosphorylate the main extrusion pump (ABCB1) related to the MDR phenotype. OBJECTIVE: In the present work, we tested a new mechanistic insight on the AZD1208 (PIM-1 specific inhibitor) under interaction with chemotherapy agents such as Daunorubicin (DNR) and Vincristine (VCR). MATERIALS AND METHODS: In order to verify a potential cytotoxic effect based on pharmacological synergism, two MDR cell lines were used: Lucena (resistant to VCR) and FEPS (resistant to DNR), both derived from the K562 non-MDR cell line, by MTT analyses. The activity of Pgp was ascertained by measuring accumulation and the directional flux of Rh123. Furthermore, we performed a molecular docking simulation to delve into the molecular mechanism of PIM-1 alone, and combined with chemotherapeutic agents (VCR and DNR). RESULTS: Our in vitro results have shown that AZD1208 alone decreases cell viability of MDR cells. However, co-exposure of AZD1208 and DNR or VCR reverses this effect. When we analyzed the ABCB1 activity AZD1208 alone was not able to affect the pump extrusion. Differently, co-exposure of AZD1208 and DNR or VCR impaired ABCB1 activity, which could be explained by compensatory expression of abcb1 or other extrusion pumps not analyzed here. Docking analysis showed that AZD1208 is capable of performing hydrophobic interactions with PIM-1 ATP- binding-site residues with stronger interaction-based negative free energy (FEB, kcal/mol) than the ATP itself, mimicking an ATP-competitive inhibitory pattern of interaction. On the same way, VCR and DNR may theoretically interact at the same biophysical environment of AZD1208 and also compete with ATP by the PIM-1 active site. These evidences suggest that AZD1208 may induce pharmacodynamic interaction with VCR and DNR, weakening its cytotoxic potential in the ATP-binding site from PIM-1 observed in the in vitro experiments. CONCLUSION: Finally, the current results could have a pre-clinical relevance potential in the rational polypharmacology strategies to prevent multiple-drugs resistance in human leukemia cancer therapy.

Who knows not where an anemone does wear his sting? Could polypeptides released from the columnar vesicles of Bunodosoma cangicum induce apoptosis in the ZF-L cell line?

We provide ultrastructural and cytological evidence that the tentacles of the sea anemone Bunodosoma cangicum does not contain cytotoxic venom. However, we show that the stimulated secretion of an apparent mixture of biomolecules containing polypeptides from the columnar vesicles of Bunodosoma cangicum is apparently a potent inducer of apoptosis in the zebrafish cell line, ZF-L. Microscopic fluorescence, cell morphology and flow cytometric assays confirm the apoptotic activity. Crude vesicle venom was partially purified by size exclusion chromatography. PAGE analysis shows that this venom contains low weight polypeptides but no measurable protein. The apoptotic activity is heat labile, and the observed peptides concurrent with this activity have a molecular weight of approximately 2000 Da. This manuscript is the first report of biologically active molecules and peptides associated with columnar vesicles of anemones, and the first to confirm that the tentacles of B. cangicum do not contain cytotoxic venom, and express spirocytes exclusively.

ABCB1 and ABCC4 efflux transporters are involved in methyl parathion detoxification in ZFL cells.

The multi-xenobiotics resistance (MXR) mechanisms are the first line of defense against toxic substances in aquatic organisms and present great importance in the adaptation related to contaminated environments. Methyl parathion (MP) is a widely used organophosphate pesticide, which has been associated to various toxic effects in organisms. In the present work, we studied the main genes related to efflux transporters in zebrafish liver (ZFL) cells exposed to MP with and without an inhibitor of ABC transporters (verapamil). The results concerning transporters activity showed that the MXR mechanism is activated to detoxify from methyl parathion. The toxic effects of MP on ZFL cells were increased in the presence of the efflux transporter inhibitor, once cell viability was significantly decreased in co-exposure experiments. The combined exposure to MP and the inhibitor caused an increase in gene expression of P-gp1 (Abcb1) and MRP4 (Abcc4), suggesting that these transporters isoforms are associated with MP efflux. In general, the expression of genes related to the antioxidant defense system (ADS) was significantly increased in ZFL cells co-exposed to MP and verapamil. These data provide useful insights for better understanding of MP detoxification mechanism in fish hepatocytes.

Effects of Double Transgenesis of Somatotrophic Axis (GH/GHR) on Skeletal Muscle Growth of Zebrafish (Danio rerio).

Transgenic fish for growth hormone (GH) has been considered as a potential technological improvement in aquaculture. In this study, a double-transgenic zebrafish was used to evaluate the effect of GH and its receptor (GHR) on muscle growth. Double transgenics reached the same length of GH transgenic, but with significantly less weight, featuring an unbalanced growth. The condition factor of GH/GHR-transgenic fish was lower than the other genotypes. Histological analysis showed a decrease in the percentage of thick muscle fibers in GH/GHR genotype of ∼ 80% in comparison to GH-transgenic line. The analysis of gene expression showed a significant decrease in genes related to muscle growth in GH/GHR genotype. It seems that concomitant overexpression of GH and GHR resulted in a strong decrease of the somatotrophic axis intracellular signaling by diminishing its principal transcription factor signal transducer and activator of transcription 5.1 (STAT5.1).