Zebrafish: a nontraditional model of traditional medicine.

With a modern rise in the use of traditional medicines has come a need for model organisms that are amenable not only to treatment with these remedies, but also to testing the large number of potential therapeutics this field presents. The high-fecundity and rapid generation time of the zebrafish makes it a natural candidate for this endeavor. Additionally, the zebrafish shares genetic, anatomic and physiologic homology to higher order vertebrates. This review surveys the present state of phytotherapy research utilizing the zebrafish model organism. The studies herein described utilize the zebrafish for investigating plant-based effectors of hypercholesterolemia, angiogenesis, Parkinson's and Alzheimer's. In addition to reviewing the present state of research in this area, the philosophical intersection of modern and traditional medical paradigms is discussed and future directions for investigations at this junction are suggested.

Determination of lymphatic vascular identity and developmental timecourse in zebrafish (Danio rerio).

Zebrafish lymphatics have been shown to share a number of characteristics with their human counterparts, making the fish a potentially useful model for studying lymphatic development and disease. The utility of the zebrafish lymphatic model would be substantially enhanced by an improved understanding of the spatiotemporal development of the primary lymphatic vasculature. The goal of this project is to identify and map the major zebrafish lymphatic structures throughout embryonic to early juvenile stages of development. Two transgenic lines, kdr-1:RASmCherryxfli1:GFP and stabilin1:YFP, were recently derived to assist in the study of developing lymphatic vasculature, but their specificity has not been rigorously tested. In the course of the present study, we experimentally validate the utility of these two marker lines as potential tools for establishing lymphatic vascular identity and visualizing developmental lymphangiogenesis. We introduced twenty nanometer red florescent microspheres into the blood vasculature of flil:GFP zebrafish and collected tiled optical z-sections at time intervals spanning early development. Three-dimensional reconstructions of the vasculature were used to differentiate between blood and lymphatic vessels. Age-matched injected embryos were compared to the two transgenic lines to further assess their specificity. We created a spatiotemporal map of the major lymphatic vessels in the developing zebrafish including a previously unidentified lymphatic vessel in the gastrointestinal tract. We conclude that the kdr-1:RASmCherryxfli1:GFP line accurately identifies developing lymphatic vessels with the exception of those associated with the gastrointestinal tract. The stabilin1:YFP line, however, is less reliable, as it marks both venous vessels and lymphatic vessels.

Evaluation of zebrafish embryos as a model for assessing inhibition of hERG.

INTRODUCTION: It has been proposed that the analysis of heart rate in zebrafish embryos can be used to assess the potential effects of compounds on hERG. The purpose of this study was to investigate the effect of compounds on the heart rate and atrioventricular dissociation in zebrafish. The compounds investigated were chosen based on the association or lack of association with QTc prolongation in the clinic. METHODS: Three-day-old embryos were incubated in buffered embryo medium. On the day of the study, fish were placed in a petri dish containing 5.0 mL of embryo medium and 125 mg/L MS-222 anesthetic. Drugs to be tested were added to the medium from a stock solution to achieve the desired target concentration. Ten fish were incubated in each concentration of drug for 80 min. Beat rates of the atrium and ventricle were recorded after the incubation by counting beats of the respective chambers using standard brightfield stereomicroscopy. RESULTS: All of the compounds associated with QT prolongation induced dissociation between the atrium and ventricular rates except D,L-sotalol and procainamide. The concentrations that induced dissociation tended to be higher than the hERG IC50. None of the negative control compounds caused atrioventricular dissociation at clinically efficacious concentrations. DISCUSSION: In conclusion, the present data demonstrate that zebrafish can be utilized to assess the effects of chemicals on hERG. However, the practical use of this assay may be difficult because of the high concentrations that must be reached to see those pharmacological effects.

Electrocardiographic characterization of embryonic zebrafish.

The zebrafish (Danio rerio) has emerged as one of the primary experimental models of developmental cardiovascular research. Recent progress in flow visualization techniques along with the existing genetic map of the species has made zebrafish amenable to a variety of experiments relating cardiac developmental structure and function. One essential tool in establishing the proper functioning of the heart is the electrocardiogram (ECG). This study presents a methodology whereby the ECGs of embryonic zebrafish could be used in assessing the electrophysiological consequences of genetically-, mechanically-, or pharmacokinetically-induced cardiac perturbations. Five day post-fertilization (dpf) embryos produced repeating bimodal ECGs with clearly distinguished atrial (P) and ventricular (R) depolarization waves. P-R intervals along with P-P intervals are cited.

Boxfishes (Teleostei: Ostraciidae) as a model system for fishes swimming with many fins: kinematics.

Swimming movements in boxfishes were much more complex and varied than classical descriptions indicated. At low to moderate rectilinear swimming speeds (<5 TL s(-1), where TL is total body length), they were entirely median- and paired-fin swimmers, apparently using their caudal fins for steering. The pectoral and median paired fins generate both the thrust needed for forward motion and the continuously varied, interacting forces required for the maintenance of rectilinearity. It was only at higher swimming speeds (above 5 TL s(-1)), when burst-and-coast swimming was used, that they became primarily body and caudal-fin swimmers. Despite their unwieldy appearance and often asynchronous fin beats, boxfish swam in a stable manner. Swimming boxfish used three gaits. Fin-beat asymmetry and a relatively non-linear swimming trajectory characterized the first gait (0--1 TL s(-1)). The beginning of the second gait (1--3 TL s(-1)) was characterized by varying fin-beat frequencies and amplitudes as well as synchrony in pectoral fin motions. The remainder of the second gait (3--5 TL s(-1)) was characterized by constant fin-beat amplitudes, varying fin-beat frequencies and increasing pectoral fin-beat asynchrony. The third gait (>5 TL s(-1)) was characterized by the use of a caudal burst-and-coast variant. Adduction was always faster than abduction in the pectoral fins. There were no measurable refractory periods between successive phases of the fin movement cycles. Dorsal and anal fin movements were synchronized at speeds greater than 2.5 TL s(-1), but were often out of phase with pectoral fin movements.

Boxfishes as unusually well-controlled autonomous underwater vehicles.

Boxfishes (family Ostraciidae) are tropical reef-dwelling marine bony fishes that have about three-fourths of their body length encased in a rigid bony test. As a result, almost all of their swimming movements derive from complex combinations of movements of their median and paired fins (MPF locomotion). In terms of both body design and swimming performance, they are among the most sophisticated examples known of naturally evolved vertebrate autonomous underwater vehicles. Quantitative studies of swimming performance, biomechanics, and energetics in one model species have shown that (i) they are surprisingly strong, fast swimmers with great endurance; (ii) classical descriptions of how they swim were incomplete: they swim at different speeds using three different gaits; (iii) they are unusually dynamically well controlled and stable during sustained and prolonged rectilinear swimming; and (iv) despite unusually high parasite (fuselage) drag, they show energetic costs of transport indistinguishable from those of much better streamlined fishes using body and caudal fin (BCF) swimming modes at similar water temperatures and over comparable ranges of swimming speeds. We summarize an analysis of these properties based on a dynamic model of swimming in these fishes. This model accounts for their control, stability, and efficiency in moving through the water at moderate speeds in terms of gait changes, of water-flow patterns over body surfaces, and of complex interactions of thrust vectors generated by fin movements.