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Blood flow starts soon after. What makes zebrafish significant for scientists is that their parts can be labeled, and because baby fish are transparent, you can see a beating heart or a forming brain through a microscope, live! What’s more, you can label blood vessels and cells in the blood, and see how blood flows through these vessels, and this is what drives following story.
The question
Since past two decades, biologists have used high-resolution techniques to obtain information hidden in the cells that make up living beings. During this quest, they identified molecules called long non coding RNA, aka lncRNA. RNA stands for ribonucleic acid, a class of molecules which act like messengers, for making building blocks of cells called proteins. What makes lncRNA different from RNA known until recently is that they do not make proteins. Instead, they
perform regulatory roles in
cellular processes. In the
past few years, thousands of
lncRNA have been discovered
in different organisms including
plants and animals. But
even with this explosion of
information, we understand
very little of what all these
lncRNA actually do in a cell.
It has been shown that
lncRNA are present in different
cells types in humans and other
animals. Incidentally, we were
interested in finding lncRNA
in a particular cell type, which
forms the inner lining of blood vessels, called endothelial cells. To combine the power of the zebrafish model and to understand the role of lncRNA in blood vessels, our lab identified lncRNA in endothelial cells in one day old zebrafish. This story is about one endothelial
Ms. Samatha Mathew || 213
lncRNA of the hundred plus identified from this earlier study. Let’s call this endothelial lncRNA ELNC. We asked the following question:
How does ELNC contribute to the function of endothelial cells and affect blood vessel biology?
The story
First, we checked whether ELNC was truly ‘non coding’, that is, does it make a protein? For this we isolated protein making factories of cells, ribosomes. If we could identify an RNA latched to ribosomes, it could make a protein. As expected, ELNC was not found along with ribosomes, suggesting that ELNC is truly ‘non coding’. Now we turned to the aspect of endothelial function of ELNC.
There are synthetic molecules that can suppress the function of RNA. This method is called “knockdown”. We introduced such a molecule against ELNC into zebrafish, which
was still at single cell stage, immediately after the sperm and egg fused through a method called microinjection. During microinjection we introduce any material in liquid form at nanolitre volumes. We did this experiment in a double- labeled zebrafish, where both endothelial cells (green) and blood cells (red) could be visualized. Knockdown or suppression of ELNC showed that the vessels were malformed in two day old zebrafish. We also saw hemorrhages in the head region of the same fishes.
This showed that disruption of ELNC was disturbing blood vessel functioning.
What if ELNC was present in excess? We artificially synthesized ELNC and introduced it into two day old zebrafish by microinjection. After a day, we could see extra vessels
Baby zebrafish are transparent, and develop organs such
as heart and brain within a day. Blood flow starts soon after. What makes zebrafish significant for scientists is that their parts can be labeled, and because baby fish are transparent, you can see a beating heart or a forming brain through a microscope, live!