Aggression and monoamines: effects of sex and social rank in zebrafish (Danio rerio)

Social defeat is a common model for studies on depression. However, such models are most often used to study aggression in males and sex differences in depression may therefore be overseen. This study investigated the potential of the zebrafish (Danio rerio) as a model for male and female aggression. In addition, effects on the brain serotonergic and dopaminergic neurotransmitter systems after agonistic interaction are well studied in many species, but not in zebrafish. We wanted to explore whether the zebrafish follows the same patterns as many other species. Therefore, the effects of agonistic interaction on brain monoaminergic activity were studied in adult male and female wild-type zebrafish. The fish interacted in pairs with one of the same sex for five days during which agonistic behaviour was quantified daily. Clear dominant/subordinate relationships developed in all pairs, both in males and females. The frequency of aggressive acts increased over time but did not differ between male and female pairs. Further, we found that dyadic agonistic interaction resulted in elevated brain serotonergic activity in subordinate zebrafish, as indicated by elevated hindbrain 5-hydroxyindoleacetic acid to serotonin ratios (5-hydroxyindolacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) ratios). We also observed a sex difference in forebrain dopamine levels and forebrain 5-HIAA/5-HT ratios, with females displaying higher concentrations of dopamine but lower 5-HIAA/5-HT ratios than males.These results suggest that zebrafish is a suitable model for studies on female aggression and sex differences in brain monoaminergic neurotransmission.     

Inhibition of central angiotensin converting enzyme ameliorates scopolamine induced memory impairment in mice: role of cholinergic neurotransmission, cerebral blood flow and brain energy metabolism

Zebrafish has been gaining popularity in behavioral genetics and behavioral neuroscience as this species offers an excellent compromise between system complexity and practical simplicity for mechanistic analyses of brain and behavior function. Recently, a number of studies started to investigate methods with which fear responses may be induced reliably in zebrafish. The ultimate goal of these studies has been to develop zebrafish models of pathological processes and to investigate the mechanisms of fear and to eventually translate the findings to the human clinic. Previously, animated image of a sympatric predator of zebrafish was shown to induce fear responses. Here we expand on this recently gained knowledge and investigate whether other moving images may induce more robust fear responses. The images investigated include the original sympatric predator, the Indian leaf fish, another sympatric predator, the needle fish, a bird silhouette moved on the side or above the tank, an expanding dot mimicking rapid approach of an object shown on the side and from above the tank, as well as non-fear inducing images including a single and a group of zebrafish. Our results indicate that although the sympatric predators do induce some fear responses, the other images, particularly the expanding dot but also the bird silhouette shown from above are more effective. The results also reveal a stimulus dependent motor pattern response repertoire of zebrafish demonstrating that perhaps univariate quantification methods may not be appropriate for uncovering the complexity of fear or anxiety related phenotypical changes in this species.     

双酚A诱导斑马鱼P53基因CDS突变的RT-PCR及序列分析

目的:研究双酚A(bisphenol A,BPA)对斑马鱼肝脏p53基因编码序列(CDS)的致突变作用。方法:试验设空白对照组与BPA暴露组,连续染毒30 d后,从斑马鱼肝脏组织中提取RNA,通过RT-PCR方法扩增得到有完整编码区序列的p53基因,并进行测序分析。结果:序列分析表明,斑马鱼P53基因编码区序列长1122 bp,编码373个氨基酸,与网上已经登陆的斑马鱼p53序列有99.9%的相似系数,而与其他生物的P53序列存在一定的差异。在0.6 mg/L浓度下染毒30 d后,BPA暴露组斑马鱼p53基因序列发生了突变。直接测序证明,它们分别在135位、311位密码子发生GAG→GGG、AGG→CGG转变,使其编码的p53蛋白发生Glu→Gly变异。结论:试验结果表明BPA对斑马鱼p53基因CDS有致突变作用,采用RT-PCR技术检测BPA诱导p53基因突变是可行的。     

Screening drugs for myocardial disease in vivo with zebrafish: an expert update

Introduction: Our understanding of the complexity of cardiovascular disease pathophysiology remains very incomplete and has hampered cardiovascular drug development over recent decades. The prevalence of cardiovascular diseases and their increasing global burden call for novel strategies to address disease biology and drug discovery.

Areas covered: This review describes the recent history of cardiovascular drug discovery using in vivo phenotype-based screening in zebrafish. The rationale for the use of this model is highlighted and the initial efforts in the fields of disease modeling and high-throughput screening are illustrated. Finally, the advantages and limitations of in vivo zebrafish screening are discussed, highlighting newer approaches, such as genome editing technologies, to accelerate our understanding of disease biology and the development of precise disease models.

Expert opinion: Full understanding and faithful modeling of specific cardiovascular disease is a rate-limiting step for cardiovascular drug discovery. The resurgence of in vivo phenotype screening together with the advancement of systems biology approaches allows for the identification of lead compounds which show efficacy on integrative disease biology in the absence of validated targets. This strategy bypasses current gaps in knowledge of disease biology and paves the way for successful drug discovery and downstream molecular target identification.     

Cadmium chloride-induced transgenerational neurotoxicity in zebrafish development

As an important environmental pollutant, the heavy metal cadmium has a significant negative impact on the stability of the ecological environment and on organismal health. Previous studies have shown that cadmium chloride can damage the nervous, skeletal, endocrine, and reproductive systems, but to our knowledge, the effects of cadmium on the behavior, neurotransmitter levels, and neuronal development in the offspring of exposed animals have not been reported. In the present study, sexually-mature zebrafish were exposed to cadmium chloride at different concentrations for 60 days, and in this background, behavior, neurotransmitters level, neuro-development and neurotransmitter metabolism was investigated in the F1 offspring. The results showed that exposure of the parental zebrafish to cadmium chloride resulted swimming speed and distance of F1 offspring significantly reduced; the levels of neurotransmitters, such as dopamine, serotonin, and acetylcholine is disrupted. neuro-development and neurotransmitter metabolism related genes expression pattern was altered, which cause zebrafish F1 offspring developmental neurotoxicity. These findings provide further insights into the harm posed by cadmium chloride to the aquatic ecosystems.     

斑马鱼几种病原菌监测

目的对斑马鱼进行几种病原菌的流行病学调查,为后续相关标准的制定提供依据。方法基于细菌的形态学及生理生化特性为基础的传统方法,并与分子生物学方法相结合,最后分离株人工感染健康斑马鱼,观察实验组发病、死亡情况以判定其对斑马鱼的致病性强弱,从而了解影响斑马鱼健康的主要病原菌。结果在所有采样单位共检出3种病原菌,包括嗜水气单胞菌、温和气单胞菌和铜绿假单胞菌。嗜水气单胞菌普遍存在于大多数被检单位,且有较强的致病力。个别单位检出温和气单胞菌和铜绿假单胞菌。温和气单胞菌致病力稍弱;铜绿假单胞菌致病力最弱,感染斑马鱼无典型临床症状,无死亡。结论嗜水气单胞菌可能造成实验用鱼设施的污染,嗜水气单胞菌已证明可以感染人类,此类潜在的人-鱼感染途径应引起重视。由此建议,嗜水气单胞菌应成为重点监控的病原菌。     

一种斑马鱼高脂血症模型的建立方法

目的：建立一种稳定可靠的斑马鱼高脂血症模型。方法：受精5天后(5 dpf, days post fertilization)的斑马鱼幼鱼随机分成普通饲料组和高胆固醇饲料模型组,普通饲料为纯蛋黄干粉,高胆固醇饲料是向纯蛋黄干粉中添加不同百分比的胆固醇配制而成,连续喂养10天后通过显微镜实时观察和幼鱼体内生理生化指标的检测进行评估。结果：添加5%胆固醇的模型组斑马鱼幼鱼体宽显著大于普通饲料组(p<0.01),其幼鱼体内总胆固醇(TC,total cholesterol)和总甘油三酯(TG,total glyceride)水平较普通饲料组显著升高(p<0.01),且低密度脂蛋白胆固醇(LDL-C,low-density lipoprotein cholesterol)水平也显著升高(p<0.05)。此外,显微镜下观察到不同百分比的高胆固醇饮食模型组幼鱼尾部血管动脉脂质沉积量均极显著高于普通饲料组(p<0.01),增加高胆固醇饲料投喂量可以加快高脂血症模型建立。结论：5%高胆固醇饲料喂养10天可以诱导斑马鱼高脂血症的发生。     

Developmental toxicity of auranofin in zebrafish embryos

Auranofin (AF) is used in clinic for the treatment of rheumatoid arthritis, repurposing of AF as an anticancer drug has just finished a phase I/II clinical trial, but the developmental toxicity of AF remains obscure. This study focused on its developmental toxicity by using zebrafish embryos. Zebrafish embryos were exposed to different concentrations (1, 2.5, 5, 10 μm ) of AF from 2 h post‐fertilization (hpf) to 72 hpf. At 72 hpf, two major developmental defects caused by AF were found, namely severe pericardial edema and hypopigmentation, when embryos were exposed to concentrations higher than 2.5 μm . Biochemical detection of oxidative stress enzyme combined with expressions of a series of genes related to oxidative stress, cardiac, metal stress and pigment formation were subsequently tested. The superoxide dismutase activity was decreased while malondialdehyde content was accumulated by AF treatment. The expression of oxidative stress‐related genes (sod1 , gpx1a , gst ), pigment‐related genes (mitfb , trp‐1a ) and one metal stress‐related gene ctr1 were all decreased by AF exposure. The expressions of cardiac‐related genes (amhc , vmhc ) and one metal‐related gene hsp70 were found to be significantly upregulated by AF exposure. These findings indicated the potential developmental toxicity of AF on zebrafish early development. Copyright © 2016 John Wiley & Sons, Ltd.     

Manufactured nanoparticles: their uptake and effects on fish—a mechanistic analysis

There is an emerging literature reporting toxic effects of manufactured nanomaterials (NMs) and nanoparticles (NPs) in fish, but the mechanistic basis of both exposure and effect are poorly understood. This paper critically evaluates some of the founding assumptions in fish toxicology, and likely mechanisms of absorption, distribution, metabolism and excretion (ADME) of NPs in fish compared to other chemicals. Then, using a case study approach, the paper compares these assumptions for two different NPs; TiO2 and C60 fullerenes. Adsorption of NPs onto the gill surface will involve similar processes in the gill microenvironment and mucus layer to other substances, but the uptake mechanisms for NPs by epithelial cells are more likely to occur via vesicular processes (e.g., endocytosis) than uptake on membrane transporters or by diffusion through the cell membranes. Target organs may include the gills, gut, liver and sometimes the brain. Information on metabolism and excretion of NPs in fish is limited; but hepatic excretion into the bile seems a more likely mechanism, rather than mainly by renal or branchial excretion. TiO2 and C60 share some common chemical properties that appear to be associated with some similar toxic effects, but there are also differences, that highlight the notion that chemical reactivity can inform toxic effect of NPs in a fundamentally similar way to other chemicals. In this paper we identify many knowledge gaps including the lack of field observations on fish and other wildlife species for exposure and effects of manufactured NMs. Systematic studies of the abiotic factors that influence bioavailability, and investigation of the cell biology that informs on the mechanisms of metabolism and excretion of NMs, will greatly advance our understanding of the potential for adverse effects. There are also opportunities to apply existing tools and techniques to fundamental studies of fish toxicology with NPs, such as perfused organs and fish cell culture systems.