The analysis of perfusion parameters using the frame-to-frame technique and the observation of small blood vessels in transparent animals using video microscopy can be tedious and very difficult because of the poor contrast of the images. Injection of a fluorescent probe (fluorescein isothiocynate, FITC) bound to a high-molecular-mass dextran improved the visibility of blood vessels, but the gray-scale histogram showed blurring at the edges of the vessels. Furthermore, injection of the fluorescent probe into the ventricle of small zebrafish (Danio rerio) embryos (body mass approximately 1 mg) often resulted in reduced cardiac activity. Digital motion analysis, however, proved to be a very effective tool for analysing the shape and performance of the circulatory system in transparent animals and tissues. By subtracting the two fields of a video frame (the odd and the even frame), any movement that occurred within the 20 ms necessary for the acquisition of one field could be visualised. The length of the shifting vector generated by this subtraction, represented a direct measure of the velocity of a moving particle, i.e. an erythrocyte in the vascular system. By accumulating shifting vectors generated from several consecutive video frames, a complete trace of the routes over which erythrocytes moved could be obtained. Thus, a cast of the vascular system, except for those tiny vessels that are not entered by erythrocytes, could be obtained. Because the gray-scale value of any given pixel or any given group of pixels increased with the number of erythrocytes passing it, digital motion analysis could also be used to visualise the distribution of blood cells in transparent tissues. This method was used to describe the development of the peripheral vascular system in zebrafish larvae up to 8 days post-fertilisation. At this stage, food intake resulted in a clear redistribution of blood between muscle tissue and the gut, and alpha-adrenergic control of peripheral blood flow was established.
New funding schemes for junior faculty staff
In celebration of our 100th anniversary, JEB has launched two new grants to support junior faculty staff working in animal comparative physiology and biomechanics who are within five years of setting up their first lab/research group. Check out our ECR Visiting Fellowships and Research Partnership Kickstart Travel Grants.
JEB@100: an interview with Monitoring Editor Stuart Egginton
Stuart Egginton reveals how he overcame the challenges of being a comparative physiologist in a medical school and how he would tell his younger self to trust his instincts when pursuing new ideas.
Travelling Fellowships from JEB
Our Travelling Fellowships offer up to £3,000 to graduate students and post-doctoral researchers wishing to make collaborative visits to other laboratories. Next deadline to apply is 27 October 2023
Feedforward and feedback control in the neuromechanics
Auke J. Ijspeert and Monica A. Daley provide an overview of key knowledge gained from comparative vertebrate experiments and insights obtained from neuromechanical simulations and robotic approaches. Read the full Centenary Review Article here.
Light fine-tunes electric fish pulses to keep them in the shade
Weakly electric fish perceive their surroundings through electric chirrups and now Ana Camargo & colleagues have revealed that light fine-tunes the fish's electric pulses to ensure that they remain scheduled beneath the mats of vegetation they use for shelter, avoiding penetrating beams of light that could give them away.
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