There were groups at the university working on zebrafish and Xenopus tropicalis (a little frog), both of which are pretty sweet experimental systems.
Zebrafish are really easy to raise, and are transparent, so you can do live microscopy on them without having to do surgery or take explants. Someone i knew worked on a project where you zap them with lasers to cause wounds, and then watch immune cells respond to the damage.
Trops are more work to raise, and the embryo is not transparent, but they are the only vertebrate for which we have powerful classical genetic tools - it's naturally diploid (two copies of each chromosome, like humans, but unlike many other animals you might consider using), but if you produce embryos using sperm which has been zapped with UV light to destroy its DNA, they're haploid, and then if you block the first cell division with a cold shock, they're diploid, but with two identical copies of each chromosome [1], so sort of functionally haploid in a way which lets you investigate the effect of mutations really easily.
Could you elaborate on this a bit? I tried to look it up but only found that some insect males are haploid.
Zebrafish are diploid (i think), but their genome underwent a duplication during evolution, so they have two copies of each gene on each chromosome (more or less), which makes them hard to do genetics on in the same way as being tetraploid does.
This might be an interesting addition. You can't usually just buy zebrafish from Petco and use them for research. There are standards in animal facilities that determine whether your fish must be "specific pathogen free" or various other levels, and so you have to generally buy them from one of a few sources if you can't bum some from a beneficent lab. When we went to purchase embryos to set up a zebrafish colony (at something like $400 for 2 females and 1 male), the facility in Europe had suffered a fire that required them to stop production for 4-6 months.
> the facility in Europe had suffered a fire that required them to stop production for 4-6 months.
This sounds very strange, unless you want to artificially create a scarcity in the supply of an animal that anybody can breed by thousands in their living room. You don't need almost any space to breed this fishes, and aquariums can be moved right?. 6 months seem too much.
I wonder why nobody has tried with another of the 100000 species of fish with transparent embryos and bypass this money-grabbing structure.
It's very complicated and quite 'messy' when it comes to the phylogeny/genetic trees. Most of the time, researchers only need those 20 fish or so once every few years, if that. Sometimes they need to interbreed these different fish to glow green and red. There are literally tens of thousands of types of fish that have to be kept. As an example: Jackson Labs has mice ready to order to the specific genotype that you want and it gets very specific [0]; zebrafish aren't quite at that level yet, but are getting there.
But the effort is worth it. Zebrafish are a great animal for studying neuro development and many other things. Many of the proposed treatments for ALS, Alzheimer's, Parkinson's, etc. got their start in zebrafish and in studying how those little vertebrates function. The effort will save countless human lives.
You wouldn't even need a different specie to bypass the money-grabbing, you only need a new facility, your own certified processes, and some clout in the industry (read citations). Hell, you could start with the fish from the expensive vendor and sell the offspring (I think, unless there's a licensing agreement involved).
https://www.youtube.com/watch?v=6v1Nfun5PqE
https://www.youtube.com/watch?v=0DB_Z0i5g_0
I don't know a lot about zebrafish (never did that postdoc), so i wasn't clear that larvae are a different stage to adults.
I wonder how they can pick up a male and two females in a larvae pool. The sexual dimorfism on young zebrafishes is close to inexistent.
I had breeded fishes more transparent that those larvae, but must admit that the macrophage video is very cool.
For a lot of fields, culture medium is not that important as long as you can run controlled experiments reproducibly. The data produced still must be tested for any greater hypothesis than "Drug X causes an upregulation of gene Y in 293 cells." Not including that rigor, or at least that precise caveat, is sloppy science. That happens some, but unfortunately, a lot of science journalism enhances these opportunities for imprecision. That's how you get to headlines like "Drug X prevents cancer!" or later, "Drug X actually CAUSES cancer!"
This is hard to solve. On the one hand, it is important to be effective communicators with the public (who do fund most of this work) and not to sit closed-lipped in an ivory tower, but on the other hand, most people are not prepared to understand the majority of the science that goes on in academic labs, or appreciate the importance or nuance. What are we supposed to do in the end? (I may be slightly off topic here).
Anyway, yes, DMEM, F12K, RPMI, etc are not perfect, no, but it's important not discount the good science that has been achieved with them. With anything, it is important to have good experimental design.
It's also still rather unrealistic. Most cells aren't directly exposed to blood plasma and all of its proteins. They are perfused by interstitial fluid which is blood plasma filtered through the capillaries.
One of the goals of some of the more modern media (as in this article) is to supplement every known necessary component of blood plasma to avoid the need for any animal-derived sera, and to make the media completely defined and standardised. This isn't new; people were doing this over a decade back when I was working on my PhD. However, the number of components in blood plasma makes this difficult, if not intractable. Most of these new media had a small amount of FBS (≤1%) to make up for the unknown components. That notwithstanding, the efforts to better understand the exact requirements are laudable. However, proving that all the needed components are present and in the correct concentrations is difficult if not impossible, since it might appear to work while causing some subtle physiological change. We might have to settle for "appears to be good enough for all common cell types". But even that would be a huge improvement upon the status quo.
Just wait until researchers realize where to obtain human blood for free...
You're looking awfully pale today Steven!
In addition, it doesn't seem as though they are able to recycle the medium. Frequently draining and refilling with fresh blood seems rather wasteful.
I've used specialist media for endothelial cells, and stem cells of various types (human and mouse, embryonic and mesenchymal). It could be up to £200 for 500ml of culture media, with a shelf life of just a week once you'd added all the frozen supplements. This makes things very costly once you scale things up.
But culture media are only the beginning of the problem. Another source of big problems are the culture conditions. Standard incubator conditions used everywhere are 37.5°C, 5% CO₂, 100% humidity. However, this is not remotely realistic, and is actively damaging to most cell types. The 5% CO₂ keeps the pH in balance (the media contains buffers). But the other 95% is regular atmosphere containing ~20.9% O₂, so the effective concentration is ~19.9% O₂. But the physiological oxygen concentration in the body's tissues is much less, a fraction of a percent.
One culture phenomenon is that "primary" cultures of isolated cells don't proliferate much, but after several "passages" they eventually become "established" and more proliferative (essentially, somewhat cancerous, and losing some of the characteristics of the original cell type). There is also a limit on the total number of passages the cells can withstand (all except the most aggressive cancer lines). This is largely down to cumulative DNA damage from oxygen. If you culture the same cells under low oxygen conditions, the cells don't become established, retain their characteristics, and can be cultured nearly indefinitely. Much more realistic. This can be done with an incubator with additional gas feeds and an oxygen sensor, which can purge the excess oxygen with N₂ then add CO₂ to 5%.
Another problem is that the culture medium is static. The cells use up its nutrients and then sit in their own waste. It needs regular replacement. But this cycle of nutrient excess and deficit and waste accumulation isn't realistic either, and may also have profound effects upon cellular physiology. Tissues in the body are continually perfused by blood plasma, maintaining nutrient levels and removing waste. This is something else which researchers should be developing; in fact, developing such systems was a part of my PhD (an unsuccessful part, I should add; it's actually quite technically difficult to perfuse patterned 3D scaffolds). But doing this for flasks and plates is a much simpler problem.
So these three major areas (media, conditions, perfusion) all contain major deviations from physiological conditions which all have the potential to grossly affect research outcomes. The fact that we have all collectively stuck with what worked for over 50 years is somewhat outrageous, particularly when for the first two there are commercial solutions which could be used today, but most people ignore. That's lazy. None of it is a "money-making scheme", though there would certainly be opportunities for media and equipment vendors.