Zebrafish Research Articles

Mitigation of PFOA/PFOS toxicity in zebrafish (Danio rerio) by oxidative stress modulation and gut microbial metabolism through the use of aquatic probiotic Lactobacillus rhamnosus

Mitigation of PFOA/PFOS toxicity in zebrafish (Danio rerio) by oxidative stress modulation and gut microbial metabolism through the use of aquatic probiotic Lactobacillus rhamnosus

High-Resolution Magic-Angle Spinning Nuclear Magnetic Resonance Identifies Impairment of Metabolism by T-2 Toxin, in Relation to Toxicity, in Zebrafish Embryo Model.

Among the widespread trichothecene mycotoxins, T-2 toxin is considered the most toxic congener. In the present study, we utilized high-resolution magic-angle spinning nuclear magnetic resonance (HRMAS NMR), coupled to the zebrafish (Danio rerio) embryo model, as a toxicometabolomics approach to elucidate the cellular, molecular and biochemical pathways associated with T-2 toxicity. Aligned with previous studies in the zebrafish embryo model, exposure to T-2 toxin was lethal in the high parts-per-billion (ppb) range, with a median lethal concentration (LC50) of 105 ppb. Exposure to the toxins was, furthermore, associated with system-specific alterations in the production of reactive oxygen species (ROS), including decreased ROS production in the liver and increased ROS in the brain region, in the exposed embryos. Moreover, metabolic profiling based on HRMAS NMR revealed the modulation of numerous, interrelated metabolites, specifically including those associated with (1) phase I and II detoxification, and antioxidant pathways; (2) disruption of the phosphocholine lipids of cell membranes; (3) mitochondrial energy metabolism, including apparent disruption of the tricarboxylic acid (TCA) cycle, and the electron transport chain of oxidative phosphorylation, as well as "upstream" effects on carbohydrate, i.e., glucose metabolism; and (4) several compensatory catabolic pathways. Taken together, these observations enabled development of an integrated, system-level model of T-2 toxicity in relation to human and animal health.

The influence of triiodothyronine on the immune response and extracellular matrix remodeling during zebrafish heart regeneration

Damage to the human heart is an irreparable process that results in a permanent impairment in cardiac function. There are, however, a number of vertebrate species including zebrafish (Danio rerio) that can regenerate their hearts following significant injury. In contrast to these regenerative species, mammals are known to have high levels of thyroid hormones, which has been proposed to play a role in this difference in regenerative capacity. However, the mechanisms through which thyroid hormones effect heart regeneration are not fully understood. Here, zebrafish were exposed to exogenous triiodothyronine (T3) for two weeks and then their hearts were damaged through cryoinjury to investigate the effect of thyroid hormones on ECM remodeling and the components of the immune response during heart regeneration. Additionally, cardiac fibroblasts derived from trout, another species of fish known to display cardiac regenerative capacity, were exposed to T3in vitro to analyze any direct effects of T3 on collagen deposition. It was found that cryoinjury induction results in an increase in myocardial stiffness, but this response was muted in T3 exposed zebrafish. The measurement of relevant marker gene transcripts suggests that T3 exposure reduces the recruitment of macrophages to the damaged zebrafish heart immediately following injury but had no effect on the regulation of collagen deposition by cultured trout fibroblasts. These results suggest that T3 effects both the immune response and ECM remodeling in zebrafish following cardiac injury.

Aspirin reduces Ponatinib-induced cardiovascular toxic phenotypes and death in zebrafish

BackgroundPonatinib (Iclusig) is an oral tyrosine kinase BCR-ABL inhibitor for treating patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myeloid leukemia (CML) who are resistant to the therapies with other tyrosine kinase inhibitors. However, adverse cardiovascular events caused by Ponatinib are a serious issue that affects patients' survival rates. Thus, it is necessary to search for candidate drugs to reduce the cardiovascular toxicity of Ponatinib. PurposeTo investigate the effects of Aspirin on Ponatinib-induced cardiovascular toxicity in zebrafish. MethodsAB strain of wild type zebrafish (Danio rerio), Tg (cmlc2: GFP) transgenic zebrafish, and Tg (gata1: dsRed) transgenic zebrafish were used as in vivo models to assess survival, blood flow, cardiac morphology, and function. Thrombus formation was detected using O-dianisidine staining. The transcriptome of zebrafish larvae treated with Ponatinib was assessed using RNA sequencing. ResultsPonatinib not only reduced survival rate but also caused cardiovascular toxic events such as pericardial edema, abnormal heart structure, low heart rate, and thrombosis. In addition, whole-body transcriptome analysis showed that Ponatinib up-regulated the expression of cyclooxygenase-1 (COX-1). Compared with other antithrombotic drugs, a COX-1 inhibitor Aspirin more effectively reduced ponatinib-induced cardiovascular toxicity events and improved the survival rate of zebrafish larvae. ConclusionOur findings suggest that Aspirin exhibits the potential to reduce Ponatinib-induced cardiovascular toxicity.

Effects of housing density on anxiety-like behavior of zebrafish in the plus maze with ramp

Population density in experimental animals is a crucial factor in maintaining the wellbeing of the organisms. Inadequate housing conditions can compromise the validity and reliability of research results, making comparisons between studies difficult. In sociable species such as zebrafish (Danio rerio), which are housed in groups, overcrowding or undercrowding represents a variable that needs to be considered. In this study, we evaluated the effects of housing at different densities for different exposure times on the anxiety response measured in the Plus Maze with Ramp test in zebrafish. The subjects (144) were divided into three large groups according to the housing time (1, 7, and 30 days). Each group was divided into six subgroups based on the density of the fish (0.25, 0.5, 1, 2, 4, 6 fish/liter, n = 8) and housed in a 4-liter aquarium. After the housing conditions, each animal was tested individually in the PMR. Time and housing density altered the exploratory behavior of zebrafish. Increased housing time reduced the time spent in the ramp arms, with groups kept for 30 days spending less time in this compartment. Density increased the time spent in the flat arms in groups with 2 and 6 fish/liter and, conversely, reduced the exploration of the ramp arms. Isolation, on the other hand, increased the exploration of the ramp arms, indicating an anxiolytic effect. In this study, we demonstrate that housing conditions can act as low-intensity chronic stressors that alter anxiety-like behavior in zebrafish when tested in the PMR protocol.

Zebrafish Maintenance Conditions Affect Behavioral and Biochemical Biomarkers: A Possible Interfering Factor on the Research Results.

Over the years, scientific research with fish models has grown at a rapid pace, and issues such as animal welfare are becoming increasingly important in various areas of animal husbandry and experimentation. Here, we evaluated whether Danio rerio behavior is affected by long-term maintenance (75 days) in an enriched environment or a chronic stress (CS) situation. In addition, we evaluated some biochemical parameters related to redox status. We concluded that long-term maintenance of zebrafish in enriched environment might induce an anxiety-like behavior pattern when these fish are faced with an acute subsequent stressor. These anxiety results, the increased school cohesion, and the absence of oxidative damage allow us to hypothesize that the fish maintained in environmental enrichment (EE) situation is more reactive, showing a strong protective reaction to the stress. From an applicable perspective, we show that both too much stress and too little stress are not ideal for zebrafish stocks. In CS situations, fish can habituate and might not respond optimally to test conditions. In opposite, the low stress promoted by environmental enrichment also renders the fish incapable of dealing with occasional stressors optimally, because now even normal conditions appear stressful to them and may elicit fear behaviors they normally would not exhibit.

A new crossognathiform fish (Teleostei: †Crossognathiformes) from San José de Gracia quarry reveals a great diversity in the Cretaceous outcrops of Mexico

We describe a new species, †Buapichthys gracilis gen. et sp. nov., based on two specimens from the Turonian deposits of the San José de Gracia quarry, Molcaxac, Puebla, central Mexico. Osteological features show this new species belongs to the order †Crossognathiformes, nesting within the suborder †Pachyrhizodontoidae. The combination of features, such as a slender body, the head with cephalic spines, three hypertrophied postcleithra, the pelvic fin posterior to the dorsal fin, the first and last dorsal pterygiophores modified into scutes, and the dorsal fin bony projections shows that †Buapichthys gracilis gen. et sp. nov. is different from other crossognathiform. This new taxon represents an increase in the group's diversity, constituting the seventh species of the order †Crossognathiformes reported in Mexico. Evaluating the crossognathiform biodiversity over time indicates that the great crossognathiform diversification occurred during the Albian until the Turonian. The Mexican fossil record significantly contributes to this diversity, with about 18% of the species recognized for this period.

515VP SCN4A loss of function zebra fish model: insights into myopathy and sudden infant death

515VP SCN4A loss of function zebra fish model: insights into myopathy and sudden infant death

Supplementation with Akkermansia muciniphila improved intestinal barrier and immunity in zebrafish (Danio rerio)

Akkermansia muciniphila (Akk), a second-generation probiotic known for its ability to regulate intestinal function in mammals, is not yet fully understood in the context of aquaculture. This study aims to investigate the effects of different forms of Akk on intestinal barrier function and immune response in zebrafish (Danio rerio) under high-fat diet conditions. The experimental groups included a control group, a high-fat diet group, an Akk group, and a group receiving various concentrations of pasteurized Akkermansia muciniphila (P-Akk) along with a high-fat diet. Evaluation methods included histological examination with hematoxylin and eosin staining, ultrastructural analysis using transmission electron microscopy, real-time fluorescence quantitative analysis, and transcriptome sequencing technology. The results showed that both the Akk and P-Akk groups exhibited a significant increase in villi number and length compared to the high-fat group. Furthermore the expression levels of claudin, claudin-2, occludin A, occludin B, and other genes were significantly upregulated, while the expression levels of intestinal proinflammatory factors genes and proteins were significantly downregulated. Compared to the high-fat group, the Akk group showed a more complete and well-preserved nucleus, mitochondria, and tight junction structures. Additionally, the morphology of intestinal epithelial microvilli in the medium and high concentration Akk group was complete and dense. The expressions of tlr2 and nf-κb were upregulated, while the expressions of myd88 and nod2 were downregulated in the medium- and high-concentration Akk groups. Akk may improve immune dysfunction in high-fat fed zebrafish through the TLR2/NF-κB signaling pathway, which requires further study. Transcriptome analysis revealed significant upregulation of the immune-related gene pigr, significant downregulation of stat3, and significant upregulation of the intercellular adhesion molecule f11r. In conclusion, dietary Akk supplementation alleviated intestinal barrier damage and immune dysfunction in high-fat zebrafish. This study provides important insights into the potential use of Akk in fish and lays the foundation for further studies on its role in fish immunity.

Preparation of Platinum Nanoparticles of Biophytum reinwardtii and Evaluation of Neuroprotective Activity of MPTP-induced Parkinson’s Disease in Zebra Fish

Aim: To evaluate the Neuroprotective activity of Biophytum reinwardtii Platinum nanoparticles Methods: Biophytum reinwerdtii platinum nanoparticles were subjected to evaluation of the neuroprotection activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine induced zebra fishes. Experimental fishes are divided into 5 groups, each containing 8 fishes. Group I is considered a normal group; Group II is a toxic group means treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine 225 mg/kg, i.p. for 5 days; Group III, IV, and V are treatment groups means treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (225 mg/kg) with 0.3 µmol, 0.4µmol, and 0.5 µmol of Biophytum reinwardtii Platinum nanoparticles respectively for 5 days. Results: In the in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine group, locomotor activity and complex I activity are decreased, Malondialdehyde levels increased, antioxidants, and catecholamines levels decreased, whereas Biophytum reinwardtii Platinum nanoparticles treated fishes exhibit significant locomotor and increased levels of antioxidants and catecholamines. Conclusion: These results suggest that Biophytum reinwardtii Platinum nanoparticles. Showed significant neuroprotection activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine -induced Parkinson’s zebra fishes.

Sodium Hypochlorite (NaClO) Disturbed Lipid Metabolism in Larval Zebrafish (Danio rerio), as Revealed by Lipidomics and Transcriptomics Analyses.

Sodium hypochlorite (NaClO) has been widely utilized since the initial outbreak of coronavirus disease (COVID-19). The widespread use of NaClO means that it can directly enter aquatic ecosystems through wastewater discharge. In this study, we analyzed the expression of PPAR-γ, FAS, and ACC1, which significantly increased in larval zebrafish following exposure to 300 μg/L NaClO for 7 days. Additionally, we examined the effects of high concentrations of NaClO on zebrafish through non-targeted lipidomics and transcriptomics. A total of 44 characteristic lipid molecules were identified using non-targeted lipidomics; an absolute quantitative analysis revealed that the contents of these subclasses of lipids decreased significantly following exposure to 300 μg/L NaClO for 7 days. The levels of triglyceride (TG), phosphatidylethanolamines (PE), and diglyceride (DG) were particularly affected. Transcriptomic analysis revealed that exposure to 300 μg/L NaClO could significantly disrupt global gene transcription in larval zebrafish. Interestingly, more than 700 differentially expressed genes (DEGs) were identified, primarily associated with lipid metabolism and glycometabolism pathways. Overall, our study provided new insights into the toxicological effects of chlorine-containing disinfectants in aquatic organisms.

Trophic transfer of carbon-14 from algae to zebrafish lead its blending in biomolecules and dysregulating metabolism via isotope effect

Abstract Carbon-14 (C-14) has been a major contributor to the human radioactive exposure dose, as discharged into environment from nuclear industry in larger quantities compared to other radionuclides. This most abundant nuclide enters the biospheric lifecycle as organically bounded C-14 (OBC-14) and threatens to public health, yet it remains unknown how this low radiotoxic nuclide induces health risks via chemical effects, e.g. isotope effect. Via establishing trophic transfer model by algae (Scenedesmus obliquus), daphnia (Daphnia magna) and zebrafish (Danio Rerio), we show that, rapidly incorporation and transformation of inorganic C-14 by algae into OBC-14 enables the blending of C-14 in biomolecules of zebrafish. We find that internalized C-14 persistently retains in brain of zebrafish, impacting on DNA methylation and inducing neuropathology alteration. Global isotope tracing metabolomics with C-14 exposure further highlight the participation of C-14 in various critical metabolic pathways, including one-carbon metabolism and nucleotide metabolism. We thus characterize the kinetic isotope effects (KIEs) for 12C/14C in the critical reaction of this metabolism via kinetic experiments and density functional theory (DFT) computations, showing that the isotopically substitution of carbon in biochemicals regulate metabolism by disrupting reaction ratios via isotope effect. Our findings suggest that nuclear industry discharged inorganic C-14 can be biotransformed to be organically bounded with biomolecules to impact metabolisms via isotope effect, providing new insights on understanding the health risk of C-14 that supposed to be a low radiotoxic nuclide.

Breaking Barriers: A Reliable Method for RNA Extraction in Zebrafish Neurodegenerative Research

Zebrafish (<em>Danio rerio</em>) is a vertebrate with unique characteristics, making it an excellent biomedical research animal model. One research area involves investigating changes in gene expression during neurodegenerative processes, aging-related changes, and behavioral studies in zebrafish. To achieve this, high-quality and quantity RNA must be extracted from zebrafish. This study aims to develop an optimized RNA extraction method from zebrafish larvae brains. After rearing and maintaining the zebrafish in suitable conditions, the larvae were separated, and their brains were extracted. Using an optimized TRIzol-based method, RNA was extracted from the zebrafish larvae's brains. For comparison, we also employed commercial kits and Trizol for RNA extraction. The quantity and quality of the extracted RNA were measured using NanoDrop, gel electrophoresis, and real-time PCR. We selected five genes: <em>gapdh</em> and <em>beta-actin </em>as housekeeping genes and three other genes expressed in the brain and nervous system (<em>bdnf, chd8, and lrp6</em>). According to NanoDrop results, all samples were purified with minimal protein and polysaccharide contamination, and the 260/280 ratio and 260/230 ratio fell within the standard range of 1.9-2.2. The amount of extracted RNA significantly increased compared to other methods (P value < 0.0001), and all the studied genes exhibited high expression. RNA extraction demonstrated both high quality and quantity. In summary, we have developed an optimized method for RNA extraction from the brains of zebrafish larvae.

The Effect of Keluwih (Artocarpus camansi) Leaves Extract On Pro-Inflammatory Expression, Growth Factors and Bodies in Zebrafish Larvae (Danio rerio) Stunting Model

Stunting is a chronic nutritional problem that occurs during the first 1000 days of life which is considered a golden window of opportunity. Indonesia has the highest prevalence compared to other middle-income countries. Keluwih (Artocarpus camansi) is known to have various compounds that are beneficial for the body such as anti-inflammatory and antioxidant. This study was conducted to determine the potential of the ethanol extract of Keluwih leaves (Artocarpus camansi) zebrafish stunting model against inflammatory markers, growth factors and body size. Artocarpus camansi leaves were extracted using the maceration method for 3x24 hours with 96% ethanol solvent. Zebrafish larvae were obtained from male and female broodstock (2:1), then induced using rotenone and ethanol extract of Artocarpus camansi leaves, then immunohistochemical staining was performed using growh factor (VEGF and TGF-β), inflammation (IL-6 and TNF-α) and body length measurements on day 9 dpf. The results showed that rotenone can provide a picture of stunting in zebrafish larvae from observations of growth factors, inflammation and body length, by administering ethanol extract of Artocarpus camansi leaves this can improve stunting conditions due to administration of rotenone, the concentration of ethanol extract of Artocarpus camansi leaves 2.5 ppm is the optimal concentration in improve stunting conditions. The ethanol extract of Artocarpus camansi leaves can improve stunting conditions by increasing the expression of growth factors, decreasing pro-inflammatory cytokines and improving body length in zebrafish larvae.

Unveiling the Exquisite Microstructural Details in Zebrafish Brain Non-Invasively Using Magnetic Resonance Imaging at 28.2 T

Zebrafish (Danio rerio) is an important animal model for a wide range of neurodegenerative diseases. However, obtaining the cellular resolution that is essential for studying the zebrafish brain remains challenging as it requires high spatial resolution and signal-to-noise ratios (SNR). In the current study, we present the first MRI results of the zebrafish brain at the state-of-the-art magnetic field strength of 28.2 T. The performance of MRI at 28.2 T was compared to 17.6 T. A 20% improvement in SNR was observed at 28.2 T as compared to 17.6 T. Excellent contrast, resolution, and SNR allowed the identification of several brain structures. The normative T1 and T2 relaxation values were established over different zebrafish brain structures at 28.2 T. To zoom into the white matter structures, we applied diffusion tensor imaging (DTI) and obtained axial, radial, and mean diffusivity, as well as fractional anisotropy, at a very high spatial resolution. Visualisation of white matter structures was achieved by short-track track-density imaging by applying the constrained spherical deconvolution method (stTDI CSD). For the first time, an algorithm for stTDI with multi-shell multi-tissue (msmt) CSD was tested on zebrafish brain data. A significant reduction in false-positive tracks from grey matter signals was observed compared to stTDI with single-shell single-tissue (ssst) CSD. This allowed the non-invasive identification of white matter structures at high resolution and contrast. Our results show that ultra-high field DTI and tractography provide reproducible and quantitative maps of fibre organisation from tiny zebrafish brains, which can be implemented in the future for a mechanistic understanding of disease-related microstructural changes in zebrafish models of various brain diseases.

DbGTi protein attenuates chromium (VI)-induced oxidative stress via activation of the Nrf2/HO-1 signalling pathway in zebrafish (Danio rerio) larval model

Hexavalent chromium (Cr (VI)) contamination poses a significant threat to environmental and human health due to its ability to induce oxidative stress. Conventional strategies to counter Cr (VI)-induced oxidative stress, like antioxidants and chelating agents, face efficacy limitations and adverse effects. The present study is intended to counteract the limitations of conventional strategies by introducing a trypsin inhibitor isolated from Dioscorea bulbifera L. tubers, known as DbGTi protein, against Cr (VI)-induced developmental toxicity and oxidative stress. Through a comprehensive array of biochemical assays, behavioural tests, and gene expression analyses, this study interprets the underlying mechanisms of the DbGTi protein. Results demonstrated that the DbGTi protein effectively restored antioxidant defense systems, including superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione S-transferase (GST), and glutathione peroxidase (GTPx), thereby mitigating cellular damage, reducing cell death, and enhancing neuro-biomarkers. qRT-PCR analysis of mRNA expression profiling revealed the upregulation of genes associated with antioxidant defense (sod, cat, gpx) and defense pathway (nrf2, hmox-1a), further highlighting the protective effects of DbGTi protein against Cr (VI)-induced oxidative stress.

Protective role of ghrelin against 6PPD-quinone-induced neurotoxicity in zebrafish larvae (Danio rerio) via the GHSR pathway

The toxicity mechanisms of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-Q), an antioxidant derivative of 6PPD via ozone reaction commonly used in rubber and tire industries, were investigated in zebrafish larvae with concentrations ranging from 0 to 50 μg/L. Despite normal hatchability, 6PPD-Q exposure led to reduced body length and swimming distance in 120 hours post-fertilization (hpf) larvae. At the highest concentration (50 μg/L), 6PPD-Q significantly impaired dopaminergic neuron development and neurotransmitter levels, including dopamine, 5-hydroxytryptamine, and glutamate. Transcriptome profiling unveiled perturbations in growth and developmental gene expression, such as upregulation of runx2a, runx2b, and ghrl (ghrelin and obestatin prepropeptide), and downregulation of stat1b, auto1, and cidea. Notably, anamorelin, a growth hormone secretagogue receptor (GHSR) agonist, recovered the behavioral deficits induced by 6PPD-Q, implying a neuroprotective role of ghrelin possibly mediated via the ghrelin/GHSR pathway. Collectively, our findings indicate that ghrelin upregulation may counteract 6PPD-Q toxicity in zebrafish larvae, shedding light on potential therapeutic avenues for mitigating the adverse effects of this antioxidant byproduct.

Synergistic modulation of endoplasmic reticulum stress pathway, oxidative DNA damage and apoptosis by β-amyrin and metformin in mitigating hyperglycemia-induced renal damage using adult zebrafish model

Diabetic nephropathy (DN) can be prevented with early therapeutic intervention in diabetic patients. Recent investigations suggest that β-amyrin, a pentacyclic triterpenoid, could offer significant benefits with its potential antihyperglycemic and nephroprotective effects. We investigated the protective effects of β-amyrin alone and combined it with metformin, the cornerstone therapy for diabetes, using a hyperglycemic adult Zebrafish (ZF) model. The ZF were subjected to hyperglycemia by immersing them in 111 mM glucose solutions. Treatment efficacy was assessed by measuring serum glucose and insulin levels and antioxidant, ER stress, apoptosis, and proinflammatory markers. ZF kidneys were also studied for immunohistochemistry and histopathology. Results revealed that the combined treatment of β-amyrin and metformin resulted in a significant decrease (p ≤ 0.05) in blood glucose levels to 104.54 ± 1.63 mg/dL, in comparison to 388.75 ± 4.32 mg/dL in the untreated diseased control group. The reduction in hyperglycemia was more pronounced than treatment with either compound alone. Moreover, treatment with the combination restored renal function in diseased ZF, leading to significantly lower (p ≤ 0.05) serum urea (SU: 19.57 ± 1.61 mg/dL) and serum creatinine (SC: 0.56 ± 0.02 mg/dL) values compared to treatment with β-amyrin (SU:27.02 ± 0.96 mg/dL; SC: 0.7 ± 0.01 mg/dL) or metformin (SU: 24.53 ± 1.29 mg/dL; SC: 0.6 ± 0.02 mg/dL) alone. The treatment also reduced oxidative stress markers, apoptosis and ER stress markers, and proinflammatory cytokines. Histopathological analysis showed improved renal architecture with significantly lower (p ≤ 0.05) renal tubular injury scores with the combination than with individual treatment. This study provides novel insights into the combined therapeutic effects of β-amyrin and metformin in mitigating hyperglycemia-induced renal damage through key molecular pathways, highlighting a potentially effective therapeutic strategy for diabetic nephropathy. The findings hold promising translational relevance for developing combination therapies aimed at improving clinical outcomes in diabetic nephropathy patients.

Immunostimulant In Fish Hatchery- A Tool In Pharmacological Research

Fish is an aquatic animal that is used as food and presently they are used in scientific research. They provide a simple system for biomedical research and hence there is an increase in demand for fish production due to its dynamic purposes. The fish are less sentient and they have a high potency with the homology of mammals hence they are used as a model in pharmacological research. The various fish that are used are zebra fish, rainbow trout fish, medaka fish, etc. Various husbandry techniques were introduced to increase the production of fish. Their intensification led to poor-quality of fish production. Immunostimulants are drugs that enhance the innate immunity of fish and increase their resistance to the disease. They are biological and synthetic compounds that increase phagocytic, lysosomal, and bactericidal activity by directly activating the immune cells and NK cells and helping in the control of disease. They are used in the pharmacological research of toxicology, genetics, cancer research, biomedicine, neurobiology, endocrinology, ecology, and gerontology, and also in the development of biology and act as a model to provide elemental knowledge on biological science.

Estimation of the cardiovascular system of Danio rerio embryos using high-frequency ultrasound scanner

Сердце эмбриона рыбы Danio rerio в возрасте 40—48 ч после оплодотворения было исследовано in vivo с помощью импульсного сканирующего акустического микроскопа в частотном диапазоне 50—100 МГц. Разработанная методика позволяет оценивать параметры сердечной деятельности в течение нескольких часов и наблюдать аномальное поведение сердца, такое как аритмия.