DNA Sampling

[froot]

WW I have a question about venom dessication. You say that it needs to be dried as fast as possible, and I would assume that one would need an agressive water scavenger that does not fume or give off odours which could taint the venom. What springs to mind for chemicals that would rapidly remove any water from the air in a dessicatoin setup, in order of aggression would be 98-100% H2SO4 and unslaked lime (CaO). Another one that I have and may work well but is a very nasty and expensive chemical - P2O5 (phosphorus pentoxide). I would imagine these chamicals would be placed in an open petri dish type container next to the open tubes with the venom samples. This is obviously placed in an airtight container forming the dessicator and carefully placed in a freezer. Would this setup suffice?
When you say that 'various proteolytic enzymes' in venom destroy each other, howcome they do not destroy each other in the venom gland? Could it not be their exposure to gasses in the air that reacts with them to break them down? (oxidise?) If this could be the case would it not be an idea to replace the air in the dessicator setup with an inert gas, perhaps nitrogen?

[armata]

They (WW & Axel) will be here Jan, after working here in W.Cape, Axel will need to tie up with some of you guys up north, poss KZN.

[WW]

Okay I have those crystals that turn from pink to blue if they are moist. I also have a huge airtight jar with a glass lid which will work nicely.

That's exactly the set-up I was thinking of!

If I am bored and get these snakes in I will have a look if it can be done safely. It is only Puff adders that you need or other stuff like Snouted cobras and Mozambique spitters too as they have a fair range too?

Puffies are the major priority, especialyl because they show so much genetic variation within SA. Obviously, it would be interesting to study this for cobras as well, but it's less of a priority, since they are much more genetically uniform. However, if you are bored....

I have heard about this "visit" from you guys for such a long time I am begining to think I should rather wait for Santa Claus.

Good things come to those who wait And we will definitely be over in January.

Cheers,

WW

[Axel]

When you say that 'various proteolytic enzymes' in venom destroy each other, howcome they do not destroy each other in the venom gland?

this is a really ineteresting question which has been largely unstudied: how do snakes store proteolytic venom toxins without a) these toxins destroying other venom components, and b) without destroying the tissues which form the venom gland. A good paper is:

Mackessy & Baxter. 2004 Bioweapons synthesis and storage: The venom gland of front-fanged snakes. Zoologischer Anzeiger 245.

The main mechanisms would appear to be that toxins are very pH specific. Conditions are very acidic in the venom gland which inhibits the toxins, but when injected into the less acidic tissues of the prey animal the toxins are activated. Snakes also produce inhibitory peptides which directly suppress toxin activity, and de-activate upon injection into prey. I think exactly how these peptides work is still largely unknown.

[WW]

WW I have a question about venom dessication. You say that it needs to be dried as fast as possible, and I would assume that one would need an agressive water scavenger that does not fume or give off odours which could taint the venom. What springs to mind for chemicals that would rapidly remove any water from the air in a dessicatoin setup, in order of aggression would be 98-100% H2SO4 and unslaked lime (CaO). Another one that I have and may work well but is a very nasty and expensive chemical - P2O5 (phosphorus pentoxide). I would imagine these chamicals would be placed in an open petri dish type container next to the open tubes with the venom samples. This is obviously placed in an airtight container forming the dessicator and carefully placed in a freezer. Would this setup suffice?

Any of those chemicals would be useful and do the trick. In the field, we normally use silica gel (non-hazardous), and simply pop the venom tubes into the gel in a closed,airtight jar. One of the key factors is not too have too much venom in a tube, if you have an Eppendorff with 1 ml of venom in it, it will take a long time to dry, whereas 0.1 ml won't take long at all. Another method we have used is a simple plastic vacuum chamber with silica gel, and one of those rubber cork-vacuum pump kits for preserving wine in a half-empty bottle (I hardly ever seem to end up with half-empty bottles, so I use the corks and pump for drying venom ). Again the venom just goes into the gel in open Eppendorff or Sarstedt tubes, and stays there unti dry.

When you say that 'various proteolytic enzymes' in venom destroy each other, howcome they do not destroy each other in the venom gland? Could it not be their exposure to gasses in the air that reacts with them to break them down? (oxidise?) If this could be the case would it not be an idea to replace the air in the dessicator setup with an inert gas, perhaps nitrogen?

Excellent Q, and something that is currently being researched in several labs. One of the lines of evidence suggests that snake venoms also contain various inhibitors of the venom toxins, and the nasties only start their work once they become dissociated from their inhibitors when the venom is ejected/injected. That may explain, among other things, how some highly myotoxic PLA2s can cause generalised skeletal muscle damage but no local damage to muscle tissue around the bite site: the inhibitors chaperone them for a while until the toxins break free, by which time they are away from the bite area, and in the general circulation - and then you get generalised rabdomyolysis, Coca-Cola coloured urine and potentially kidney failure, as for instance in Crotalus durissus.

Cheers,

WW

[froot]

Thank you for the replies, so then one can speculate that these inhibitors could be pH specific as Axel mentioned, raise the pH and they no longer inhibit the toxins. If this is the case, I wonder if one could preserve a venom in a pH buffer of some sort, and if this would interfere with tests done on the venom. Any studies done on the venom gland with regards to what it is in the soup that lowers the pH, as in the molecular formula?

I'm not sure if this is straying from the topic but shout if you think I'm going off on a tangent here.

[Axel]

I think citrate, a common component of many venoms, is though to be responsible for lowering and buffering the pH. Froot: if you pm me your email I can send some papers on the subject.

[Bushviper]

Okay now when I start milking how do you find the udder? On cows it is between the back legs and on elephants it is between the front legs. Snakes dont have legs!

[Quintin]

Okay now when I start milking how do you find the udder? On cows it is between the back legs and on elephants it is between the front legs. Snakes dont have legs!

LOL!!!

Q

[WW]

Okay now when I start milking how do you find the udder? On cows it is between the back legs and on elephants it is between the front legs. Snakes dont have legs!

Take a python, find the spurs, and take it from there. Then take any other snake and do it without the spurs

[atropos]

Hi again armata, ww and axel. When do you want the samples? We have a few but would like to fill all the vials before sending them over. Thanks. G

[Axel]

Hi again armata, ww and axel. When do you want the samples? We have a few but would like to fill all the vials before sending them over. Thanks. G

Hi Guu,

many thanks for collecting the samples. What species have you managed to get?

you can give/post the samples to armata, who will pass them on to us. Alternatively, if you live around Gauteng, I will be at the THA meeting on the 30th of Jan so you could give them to me directly. We will make sure you get some fresh tubes too.

thanks again, Axel.

[atropos]

Hi axel. So far we have Dasypeltis scabra, Bitis arietans and Bitis caudalis all from namibia. I also know of a few places to find Lycodonomorphus rufulus so hope to add those as well. Think i just need some smaller scissors Haha. I'm in cape town so i'll send the vials once i got a few more samples. Thanks for letting me participate. G

[Axel]

So far we have Dasypeltis scabra, Bitis arietans and Bitis caudalis all from namibia.

WOW! That's fantastic! We don't have a single Namibian specimen so far, so these samples are critical. Particularly for Dasypeltis and the puffies, Namibian specimens are essential if we are to understand DNA variation across the whole of Southern Africa.

Thanks ever so much... and keep them coming!

BTW. Has anyone else managed to get samples? It would be nice for me to be able to keep track of how things are going from the UK. Maybe we could keep this topic going for people to post their stories and experiences while collecting DNA samples?

[Mongoose]

I have collected stuff from south Mozambique and Mpumalanga provinces mainly.