Glow in the Dark Snake (Part 2)

*FYI - If you are a grant proposal reviewer then yes, I have a 2009 GC Round 4 proposal submitted for review.

Part 2 – Sperm Mediated Chromosome Transfer (SMCT)

There are always questions to any hypothesis.

Can a cell handle an extra chromosome? Sure it can. Think about a person with Down’s syndrome – they have an extra chromosome 21 (in cases of trisomy) - the physiological problems they have aren’t due directly to the fact that the extra chromosome is present but because the genes on the extra chromosomal material are being expressed. This is why a Robertosonian Translocation elicits the same effect. The important thing to note is that almost every cell in their body (except the red blood cells etc.) has this extra copy which means that a cell definitely has the machinery to replicate and handle an extra chromosome. Plants actually have lots of B-chromosomes which are extra chromosomes. Even chickens have micro-chromosomes.

Telomeric sequences contain a lot of info – do you really need them? No. You could build a circular artificial chromosome and eliminate them completely. Now you just need the origin of replication, the centromere, and the gene that you want. Cool huh?

Who would fund something like this? For snakes you’d have to find private investors kind of like Genetic Savings and Clone who were doing cat cloning stuff. Cat cloning is really hard!! So what you’d do is grow snake fetal fibroblasts, harvest the cells at mitotic arrest, lyse the cells, sort the chromosomes, have someone take one of the chromosomes and build a cDNA library of it, put together the artificial chromosome (including your ‘glow in the dark’ gene), mix with sperm to the right ratio, then inseminate a gravid, pre-ovulatory snake. The cool thing is, if you did design this chromosome, you would most likely be able to put it into any snake species (their own sperm of course) since its cell protein complements should, evolutionarily, be very similar.

But to prove the overall concept you could start in chickens or turkeys for which there should be, though not necessarily, substantial interest from the poultry industry. For instance, you could design artificial chromosomes with genes for resistances to bacteria or Avian flu virus into chickens and even change them every couple generations or so to keep up with inherent pathogen mutation rates.

Part 1 Part 3

- Just a peasant

Photo of a human artificial chromosome from the lab of Dr. Gyula Hadlaczk in Hungary

Glow in the Dark Snake?

*FYI - If you are a grant proposal reviewer then yes, I have a 2009 GC Round 4 proposal submitted for review.

That’s how it began for me – I wanted to make a snake that would glow in the dark. I wanted to insert a gene for luciferase (from the firefly) into a snake. What an awesome pet! It would be great but there was a catch – how do you do in vitro gene insertion into the embryo of a reptile? Mammals are relatively easy since you take the eggs out, modify them, and then put them back in the uterus. Although some reptiles give birth to live young, most reptiles lay eggs and must deposit a shell around the embryo when they ovulate. I suppose live bearing reptiles would be easiest but either way it gets very complicated to put the modified zygote back into the reproductive tract where it can be properly excreted.

But it also occurred to me that birds have a similar problem – the fertilized egg must pass through the magnum and isthmus to be coated with a shell when the egg is ovulated. Certainly the poultry industry would very interested in this strategy - Tyson Foods I'm looking at you! So I started thinking about how I would accomplish this. Might it be possible by doing in vivo laparoscopic follicular aspiration, followed by a quick ex vivo egg surgery, and finished with laparoscopic re-implantation? But these eggs are relatively large - could you even use laparoscopy? Wow! There were a lot of things to consider. But is there an easier way?

There was once a crazy idea about attaching a gene to the head of a sperm and letting the sperm carry the DNA to the egg. It was known as Sperm Mediated Gene Transfer (SMGT). But there were many technical problems including the fact that the gene did not insert into the chromosomes and therefore did not last through multiple replications of the cells. It was just present in the egg for a little while but apparently not permanent. Also, if the gene did insert into a chromosome it would not necessarily be expressed. So this idea basically fizzled out on a technicality. Incidentally, multi-generational SMGT could not be reproduced in other labs making the initial reports suspect.

Well, I really want to see a snake that glows in the dark! So I started thinking – what does a gene need in order to replicate? Well a gene sits on a chromosome and this chromosome needs at least an Origin of Replication, a centromere, and a telomere. When you really want to win the Tour de France you don't send just one cyclist - you send the whole team. So, what if we sent a whole chromosome instead of just a DNA fragment?

Hypothesis: Sperm Mediated Chromosome Transfer (SMCT) – use a sperm to deliver an entire chromosome to the egg.

Go to part 2 to some interesting notes about this hypothesis

- Just a peasant

Photo of two cats - the one on the right is expressing a gene that glows red under UV black light. From Gyeongsang National University in South Korea - video here.

Fish food that uses insects instead of fish

Problem: Currently, world aquaculture and mariculture systems use fish feed that has been made from other fish. It takes about 6 kg of wild caught fish to make 1 kg of farmed fish. The world’s fisheries are under increasing pressure to produce enough fish and this ratio needed to support aquaculture is sad indeed. In fact, there were a couple of years Japan’s aquaculture industry was facing a shortage of fish feed. Finding ways to save over exploited oceans is important to me.

Hypothesis: There are a lot of good reasons to use insects. Kilogram for kilogram they have more protein than any vertebrate. Insects also produce long chain fatty acids needed by fishes who ultimately make n-3 and n-6 fatty acids. Insects are already a food of many fish species. Insects are easy to produce in large quantities using just agricultural byproducts.

Experiment: In 1998, under the UROP program of the University of Minnesota, I attempted to make fish feed that used protein derived from insects as a replacement to the fish protein normally used. I had a major problem actually baking the food pellets where they became extremely dry and crumbly and when I graduated I went on to other things. Making fish pellets was a lot harder than I thought it would be - hahaha!

In less than two weeks I grew 10 kg of house fly larvae in the entomology lab at U of MN.

So I still think this is an awesome idea. But I mainly mention it here because I noticed another lab did an experiment last year. So now I put it right here on a blog so that just maybe some other labs will take up this idea. Save the oceans!

- Just a peasant

Photo of an Archerfish shooting its insect prey from the on-line Encyclopedia Britannica