A Simple Blood Vessel Imaging Protocol for Live Zebrafish Larva.

Zebrafish larva is a simple model system to study blood vessel development because of its excellent optical properties. Current methods to study blood vessels in zebrafish involve utilizing either blood vessel-specific transgenic lines or specialized techniques such as microangiography and video capillaroscopy. In this study, we have developed a simple protocol using ImageJ to observe the blood vessels of live zebrafish larva at different developmental stages, namely 1- to 4-day postfertilization (dpf). To validate this protocol, we treated 1 dpf zebrafish embryos with 100 µM quercetin, and analyzed the impaired development of subintestinal vein in the quercetin-treated 3 dpf larvae.

Identification of zebrafish fumarate hydratase active site by molecular docking and simulation studies.

Fumarate hydratase (FH), one of the members of TCA cycle, acts as a catalyte for the synthesis of malate from fumarate. FH has been proposed to play as a tumour suppressor leading to the pathogenicity of leiomyomas, renal cell carcinoma and paraganglioma. Mutations in the active site of FH lead to alteration in the protein structure. Similarly, binding of several chemical inhibitors to the active site also leads to the disruption of protein structural integrity thereby leading to protein dysfunction. Therefore, in order to address this mechanism leading to cancer, the binding efficiency of potential human FH inhibitor citrate to zebrafish fh has been extensively analysed in this study by molecular docking and simulation experiments followed by quantification of fumarate hydratase enzyme activity to validate and confirm the findings. Molecular docking revealed stronger interaction of zebrafish fh protein with inhibitor citrate when compared to natural substrate fumarate. Study on the dynamics of docked structures further confirmed that citrate was found to possess more binding affinity than fumarate. In vitro biochemical analysis also revealed concentration dependent potential inhibitory effect of citrate on zebrafish fh, thus confirming the findings of the in-silico experiments.Communicated by Ramaswamy H. Sarma.

A simple method to study motor and non-motor behaviors in adult zebrafish.

BACKGROUND: Motor and non-motor behavior analyses are increasingly utilizied in drug discovery and screening, detection of neurobehavioral disorders and chemical toxicology. The emergence of computational approaches has helped to develop different tools to analyse complex behaviors. Analysis of locomotor behavior helps in understanding the motor neuron disorders like Parkinson's Disease. Although many animal models are available to study the locomotion, adult zebrafish has emerged as a simple and efficient model to study this behavior. An inexpensive and easily customizable tool is required to replace the licensed and expensive set-up to analyse the locomotor behavior. NEW METHOD: In this study we have optimized the ImageJ plugin wrMTrck to analyse motor and non-motor behaviors in adult zebrafish. We have generated a macro to simplify the preprocessing and tracking. Subsequently, we have developed a data analysis sheet to analyse various behavioral end points. RESULTS: We have successfully developed an inexpensive video acquisition set-up and optimized wrMTrck for adult zebrafish. In order to demonstrate the efficacy of this method, adult zebrafish were injected with MPTP and motor and non-motor behaviors were analysed. Expectedly, MPTP injected fish showed decrease in dopamine level and dat expression level, which subsequently led to locomotor behavioral defects as well as anxiety, a non-motor symptom of PD. COMPARISON WITH EXISTING METHOD(S): Further, the obtained results were validated by another ImageJ macro developed by Pelkowski et al. (2011) and we observed identical trajectories. CONCLUSIONS: The usefulness of popular ImageJ plugin wrMTrck and this extended protocol will be helpful to quantify motor and non-motor behavioral parameters.

Effect of Fadrozole Exposure on Socioreproductive Behaviors and Neurochemical Parameters in Betta splendens.

Induction of all-male population in Siamese fighting fish, Betta splendens, has potential application in ornamental fish trade. In addition, the sexually dimorphic nature of aggressive behavior exhibited by this species has made it into an emerging model for behavioral studies. Fadrozole, an aromatase inhibitor, which has been used widely in masculinization, has captivated us to use it in this study. Twenty one days postfertilization (dpf), B. splendens fry were subjected to discrete immersion treatment with various concentrations of fadrozole, and eventually, analyses of various socioreproductive behaviors and analyses of stress markers such as dopamine in brain samples, sex hormones, cortisol, and glucose in plasma samples were performed. We observed that 91% of 50 µg/L fadrozole treated fish developed as males. Interestingly, reproductive analyses of these males gave rise to two subgroups (A and B). Subsequent sociobehavioral analyses demonstrated a timid and subdued behavior in subgroup B males. Furthermore, estimation of stress markers such as dopamine levels in the brain tissue, cortisol, and glucose levels in blood plasma and sex hormone levels in blood plasma exhibited an endocrine disruption-mediated stress leading to altered behavior in these males. These findings will help in understanding the fadrozole-mediated masculinization and behavioral alterations following endocrine disruption.

Analyzing Locomotor Activity in Zebrafish Larvae Using wrMTrck.

The zebrafish has emerged as a new model system in behavioral neurobiology research. There are numerous assays available to analyze locomotor behavior, but most of these assays require sophisticated equipment and proprietary software. A freely available plugin, wrMTrck, originally developed to analyze locomotor response in Caenorhabditis elegans, has been used in this study to measure locomotion in zebrafish.