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[P]
FUN WITH FRUIT

By Sgt York in Science
Wed Oct 03, 2007 at 04:44:15 PM EST
Tags: Science, fruit, recipe (all tags)
Science

YOU WILL NEED:

  • A strawberry
  • Some powdered meat tenderizer (papain)
  • Some liquid soap
  • A fork
  • Two small cups (shot glasses are great)
  • A coffee filter
  • Some rubbing alcohol


Wanna see some DNA? This is a fun little demo that works well at parties. The supplies are found in most people's kitchens; I've found the rarest is meat tenderizer.

This extracts DNA from a strawberry. You can use just about any soft fruit, but strawberries are best; they're octoploid (each cell has 8 sets of chromosomes), so there's a shitload of DNA in them. Basically, you just squish up the strawberry in a little bit of water and add a touch* each of soap and meat tenderizer. The soap disrupts the membranes and the protein secondary & tertiary structure in the tissue, allowing access to the DNA. The meat tenderizer contains proteases (papain, typically) that chew up the proteins that bind to the DNA, helping it get out into the solution. It also chews up the DNAses in the prep. The coffee filter gets rid of the trash, cleaning up the solution. The isopropyl alcohol (rubbing alcohol) then precipitates the DNA out of solution. Here's the rundown:

  1. Cut the crown off the strawberry; it just gets in the way.
  2. Put the strawberry in a cup.
  3. Add a little water, a little meat tenderizer, and a little liquid soap.
  4. Squish it all up with the fork. Or your fingers. Whatever is handy.
  5. Let it stand for a minute or two. If you want to increase efficiency, heat it up first. Get it up to about 50-60 degrees C (quickly, if possible, like in a water bath), let it cool a bit and then add the meat tenderizer. The stuff we use in the lab works best at 50C, but I don't know the heat tolerance of papain. I know it works at room temp, though. It might break down at high temp. The high temp part denatures the strawberry proteins, most importantly the DNA eating proteins (DNAses).
  6. Pour the stuff through the coffee filter into the other glass. A good way to do this is to put the filter on top of the second glass and dump the contents on it. Then gather up the sides of the filter and squeeze the liquid into the glass.
  7. Now add ~2 volumes of the rubbing alcohol. For best yield, store the alcohol in the freezer (it won't freeze) and put the glass in the freezer to precipitate (again, it won't freeze solid). However, this will limit your view of the DNA precipitating (which is pretty cool) due to the frost on the glass from the cold alcohol. I'd suggest doing it all at room temp.
  8. Stir around with the fork; you will see little white threads start to form; they may look a little yellowish. It will slowly condense into a tighter and tighter ball that will eventually look like a tangle of thread.
  9. If you want, you can pull it out, dry it out and redissolve it in water. It will make a viscous solution if it's highly concentrated. It's pretty soluble as long as you dry it out all the way.
  10. You can store it in water for a while, but it will degrade over time. If you want to keep it, dry it out and keep it in the freezer.
Like I said, strawberries are best for this but you can use anything that's not too dense. And yes, you could do your own DNA. There's not enough in a cheek scraping or a hair follicle to visualize. Blood doesn't have a lot in it either. Most of the cells are erythrocytes; no DNA in those.

If you want your own, just rub one off. Sperm should yield to this technique quite well. However, when doing this as a party trick, stick to the strawberries.

Side story: Protease is fun. I have to get DNA samples from mouse tails, so the lysis buffer and proteases we use are pretty strong; in fact, the proteases are from the same fungi that would rot the dead mouse. They do a damn good job.

We used to keep a 50mL conical tube in the lab, full of lysis buffer and leftover proteinase K (you thaw it out in aliquots; each has enough to do 20 tails. If you have 30 tails to prep, you have a little stuff left over...and it goes in the tube).

The tube was for the cockroaches. We'd catch 'em and stick 'em in the conical. They'd slowly dissolve over the course of a few days. Eventually, we had this tube full of degraded cockroaches. One day, we extracted the stuff and ran it on a low-stringency Southern to look for gene similarities in invertebrates. Beware the bored molecular biologists.

* Touch = about as small an amount as you can manage to add.

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Poll
So, you gonna extract your own jizz?
o That's disgusting; yes 65%
o That's disgusting; no 10%
o I'm a chick, no 2%
o I'm a chick, I'm gonna do my boyfriend's 7%
o That's stupid, no 5%
o No, that's fruity 10%

Votes: 40
Results | Other Polls

Related Links
o Also by Sgt York


Display: Sort:
FUN WITH FRUIT | 80 comments (52 topical, 28 editorial, 0 hidden)
i did it with ice-minus bacteria and strawberries (3.00 / 2) (#2)
by circletimessquare on Tue Oct 02, 2007 at 12:09:40 PM EST

and made a delicious shake


The tigers of wrath are wiser than the horses of instruction.

Other uses (3.00 / 2) (#3)
by Sgt York on Tue Oct 02, 2007 at 12:14:19 PM EST

Frozen strawberries, vanilla frozen yogurt, pineapple chunks, and pineapple juice (rum optional). Blend well. More yogurt = sweeter. More pinepple/berries = tart

DELICIOUS.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

What I am missing in this shake: (none / 1) (#23)
by Psychopath on Tue Oct 02, 2007 at 07:18:52 PM EST

the meat and its tenderizer!
--
The only antidote to mental suffering is physical pain. -- Karl Marx
[ Parent ]
Probably... (none / 1) (#74)
by Eccles on Fri Oct 05, 2007 at 04:09:31 PM EST

...not recommended you do this with jizz, though. But to each his or her own...

[ Parent ]
Wow (3.00 / 7) (#4)
by BJH on Tue Oct 02, 2007 at 12:28:10 PM EST

I stand in awe of the truly kickass parties that you frequent.
I can't think of anything better to do at a party than extract DNA from vegetable matter. WOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHHHHHHHH-YEAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HHHHHHHH!!!1!one!!1
--
Roses are red, violets are blue.
I'm schizophrenic, and so am I.
-- Oscar Levant

Well (3.00 / 3) (#7)
by Sgt York on Tue Oct 02, 2007 at 12:54:19 PM EST

that's why I included the spooge option, for the more lively parties. make it a contest; "Who can make the most DNA?" , "How can I be sure you won't knock me up?"

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

It's the Humane Bukkake Genome Project. $ (3.00 / 11) (#14)
by localroger on Tue Oct 02, 2007 at 04:51:06 PM EST



alexboko: I think, how do animals view our behavior?
Sgt York: Opening
[ Parent ]
We have created a new porn niche (3.00 / 12) (#15)
by Sgt York on Tue Oct 02, 2007 at 04:57:34 PM EST

Women covered in DNA extracted from sperm. PURE bukkake

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Fuck yeah! A Science Article (3.00 / 2) (#6)
by Josh Smith II on Tue Oct 02, 2007 at 12:47:57 PM EST

I'll FP this just on principle, haven't even read the damned thing. We need more science and tech shit and less "omg paid accounts/teh UN".

-- Josh Smith recommends you take a hulver hike.
+1 FP. Can you tell me how to clone a dinosaur? (3.00 / 8) (#8)
by xC0000005 on Tue Oct 02, 2007 at 01:12:13 PM EST

I've got this idea for a theme park. I thought about cloning jurassic bees but they're tiny (similar to the dwarf honeybee) and not nearly impressive as a t-rex would be.

Voice of the Hive - Beekeeping and Bees for those who don't
maybe not so crazy (3.00 / 2) (#10)
by circletimessquare on Tue Oct 02, 2007 at 02:08:30 PM EST

if jurassic honey turns into amber

then there has to be a lot of bees stuck out there


The tigers of wrath are wiser than the horses of instruction.

[ Parent ]

Amber is fossilised tree sap (3.00 / 2) (#64)
by some nerd on Wed Oct 03, 2007 at 06:40:35 PM EST

and it's not unusual to find insects in it, including mosquitoes. Unfortunately DNA is a fairly unstable molecule so any dino DNA has long since been chopped into timy peices by chemical processes / radiation. And no, "zomg fill in the missing bits with frog DNA" wouldn't work.

--
Home Sweet Home

[ Parent ]
maybe duct tape? (3.00 / 2) (#66)
by circletimessquare on Thu Oct 04, 2007 at 01:30:46 AM EST

duct tape fixes everything


The tigers of wrath are wiser than the horses of instruction.

[ Parent ]
Won't work (3.00 / 6) (#20)
by Sgt York on Tue Oct 02, 2007 at 05:13:21 PM EST

You need frog DNA to clone dinosaurs, and if you put that in an insect it would just eat itself.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Thanks, Doctor Science! (3.00 / 3) (#25)
by xC0000005 on Tue Oct 02, 2007 at 08:42:33 PM EST

I knew there was some reason why it hadn't been done.

Voice of the Hive - Beekeeping and Bees for those who don't
[ Parent ]
My wife used to be a biologist (3.00 / 4) (#11)
by MichaelCrawford on Tue Oct 02, 2007 at 02:08:42 PM EST

... and told me that soap's ability to tear apart cell membranes is the reason that washing your hands with soap will kill any bacteria on them, and that it's not really necessary to use antibacterial soap.


Looking for some free songs?


does that kill your cells too? (3.00 / 2) (#16)
by United Fools on Tue Oct 02, 2007 at 05:00:18 PM EST


We are united, we are fools, and we are America!
[ Parent ]
I have often wondered that, but never asked (3.00 / 3) (#18)
by MichaelCrawford on Tue Oct 02, 2007 at 05:10:20 PM EST

However, the outer layer of skin is dead cells.

One other thing she told me, I don't know the right word for it, but bacteria have a fundamentally different chemistry than people do, so it's not hard to kill off most bacteria infections without harming the patient.

But fungal cells are more similar to human cells, and so fungal infections are very hard to treat.


Looking for some free songs?


[ Parent ]

One of the big differences (3.00 / 2) (#56)
by some nerd on Wed Oct 03, 2007 at 01:48:50 PM EST

is that bacteria have cell walls1 (animal cells don't) containing Peptidoglycan. Messing with this is how some antibiotics e.g. Penicillin and its derivatives work.

1Except Mycoplasma

--
Home Sweet Home

[ Parent ]

Antifungals (none / 1) (#67)
by Pietro on Thu Oct 04, 2007 at 05:48:51 AM EST

Yeah, fungi and animals are eukaryotes while bacteria are prokaryotes. The similarities mean that there's less potential for selective toxicity when treating a fungal infection than in a bacterial infection, but really the fact that fungal infections are less studied than bacterial ones contributes a lot to the lack of effective (and non-toxic) antifungal agents. A lot of our antifungals right now screw around with ergosterol, which fungi have in their membranes instead of cholesterol.

[ Parent ]
Cells on your skin surface (3.00 / 4) (#19)
by Sgt York on Tue Oct 02, 2007 at 05:11:02 PM EST

are dead anyway.

Actually, most of what soap does is wash away the stuff the bugs are sticking to. Bugs aren't that good at sticking to clean, dry skin. However, the oils our bodies secrete are very good at sticking to our skin, and bugs are good at sticking to those oils.

When you wash your hands, you solubilize those (and other) oils, as well as physically washing away dirt that has stuck to your skin. The oils come off and take the bugs with them, right down the drain.

I've had bacteria grow in solutions containing as much as 0.5% SDS (the active ingredient of liquid soaps), and AFAIK, that's pretty damn high for hand soap. It sure foams like a bitch....

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

The whole point of skin (none / 1) (#34)
by daveybaby on Wed Oct 03, 2007 at 07:32:33 AM EST

is that it's there to protect your more delicate cells from the outside world. Drinking or injecting soap is not likely to do you much good.

[ Parent ]
wait..... (none / 1) (#38)
by Sgt York on Wed Oct 03, 2007 at 09:19:22 AM EST

...what?

you're right, of course, but why did you bother saying that?

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

I... dont... know.... (3.00 / 3) (#43)
by daveybaby on Wed Oct 03, 2007 at 11:14:33 AM EST

Um. I may have had a reason somewhere and posted to the wrong place or something.

Oh well, at least it's correct and pointless...

[ Parent ]

I like breakdancing (3.00 / 2) (#52)
by Hiphopopotamus on Wed Oct 03, 2007 at 12:49:24 PM EST

but I'm no good at it.
_________________

I'm In LOVE!
[ Parent ]

Black people in the 1970's (3.00 / 2) (#55)
by Booger on Wed Oct 03, 2007 at 01:18:11 PM EST

often sported a long bushy hairstyle called an "afro".

-
I did think of a derogatory term for white people--RICH. Call some white guy RICH and it doesn't matter how much money they have, they'll start squealin about how oh they wish they were rich.--tdillo
[ Parent ]

Really? Damn we did not consider that... (none / 0) (#65)
by United Fools on Wed Oct 03, 2007 at 09:25:28 PM EST

Fools can learn new things every day

(and forget them the next day)

We are united, we are fools, and we are America!
[ Parent ]

Not just dead, (none / 1) (#70)
by sudogeek on Thu Oct 04, 2007 at 07:51:03 PM EST

but "keratinized" which means that the cell is mostly full of a certain protein, keratin. The keratinization process is a fascinating varation on the process of apoptosis (progammed cell death) using many of the same mechanisms.

You're an arrogant, condescending, ignorant dipshit. - trhurler
[ Parent ]
yout epidermus is dead already (none / 0) (#71)
by newb4b0 on Fri Oct 05, 2007 at 01:23:59 AM EST

.

http://www.netmoneychat.com| NetMoneyChat Forums. No Registration necessary. Ya'll.
[ Parent ]

edit nit (3.00 / 7) (#13)
by SIGNOR SPAGHETTI on Tue Oct 02, 2007 at 03:44:27 PM EST

Strawberries have 8 *sets* of chromosomes.

Onions work very well too, they have like 10 times the DNA of human sperm, but you'll need a blender to rupture their cellulose cell walls, I don't think you can spill their guts with just fork. Besides, blenders are violent; white people like that; it's not really science unless something smells, goes bang, or is rent apart. You can get consistently better results if the alcohol is chilled and if you work with the filtrate over ice. The meat tenderizer also contains salt, which keeps the DNA intact before it is precipitated in alcohol.

--
Stop dreaming and finish your spaghetti.

Edited the chromos (3.00 / 4) (#17)
by Sgt York on Tue Oct 02, 2007 at 05:05:59 PM EST

and inserted a little about cold alcohol; thanks.

However, the salt doesn't really help stabilize the DNA, it just makes the pellet more visible. I normally wash the salt out of my DNA preps at the end, and it just turns the pellet clear.

The best way to stabilize DNA is to keep it buffered at a slightly alkaline pH (~8.0) and pull out any divalent cations with something like EDTA. Most DNAses won't work without divalents, and if the pH is kept a little high, the DNA can't autohydrolyze.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

WIPO: that's fruit. (3.00 / 2) (#26)
by localroger on Tue Oct 02, 2007 at 08:48:31 PM EST



alexboko: I think, how do animals view our behavior?
Sgt York: Opening
WIPO no longer! -rn (none / 1) (#28)
by Sgt York on Tue Oct 02, 2007 at 11:10:18 PM EST


There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Right, i've done that. (none / 1) (#49)
by daveybaby on Wed Oct 03, 2007 at 12:18:01 PM EST

Now, how do i sequence it?

I was considering (3.00 / 4) (#51)
by Sgt York on Wed Oct 03, 2007 at 12:48:15 PM EST

Writing a few "Science, the hard way" articles about how I used to do stuff in a my old DIY school of thought lab. We made our own antibodies, cloned genes for our own enzyme reagents, did radioimmunoassays from scratch, made and screened lambda libraries, did chromosome walking, old-school dideoxy sequencing with huge, paper-thin acrylamide gels... ahhhhhh, good times.

Then take those and compare them to how it's done today, just 10 years later. It's all automated now. Takes less than half the time and more than 10 times the cost.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Do it. (3.00 / 2) (#54)
by daveybaby on Wed Oct 03, 2007 at 01:09:35 PM EST

We could do with some decent science articles around here for once.

Also, if those pesky international terrorists turn up looking for instructions on how to mass produce bioweapons, the k5 membership will go up.

[ Parent ]

and the k5 quality. (nt) (3.00 / 2) (#57)
by khallow on Wed Oct 03, 2007 at 02:30:41 PM EST


Stating the obvious since 1969.
[ Parent ]

Less blinkered jingoism (none / 1) (#59)
by daveybaby on Wed Oct 03, 2007 at 02:50:40 PM EST

and more rational debate.

[ Parent ]
If you want to see how it was done, (none / 1) (#69)
by sudogeek on Thu Oct 04, 2007 at 07:47:17 PM EST

Look around for an old copy of Maniatis' manual.

Its a fascinating read now. Back in the day, we used to walk to the lab in the snow uphill - both ways - and spend hours  re-purifying and recrystallizing guanidium bromide and all those other reagents from the crap that Bio-Rad, Aldrich, or Sigma supplied. In fact, I can remember making preps of B. thermophilus DNAse and doing PCR by hand, long before Perkin-Elmer can out with their device.

You're an arrogant, condescending, ignorant dipshit. - trhurler
[ Parent ]

eh? how's that sonny? (none / 0) (#75)
by Sgt York on Fri Oct 05, 2007 at 04:23:18 PM EST

chloramine T, I125, protein A and KCl, IIRC. Old school "ELISA", aka RIA.

Damn, I'm glad I've equilibrated my last bottle of phenol.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Must do this during next party (3.00 / 4) (#53)
by hatshepsut on Wed Oct 03, 2007 at 12:49:54 PM EST

must also get friend drunk enough to volunteer.....

hmmm, wonder about spirulina (none / 1) (#58)
by khallow on Wed Oct 03, 2007 at 02:35:39 PM EST

That algae is supposed to have a lot of DNA material and when processed for human consumption usually comes with the cell walls already disrupted. Maybe they've figured out how to filter out the genetic material, since supposedly the DNA adds too much nitrogen to the diet making nasty things like kidney stones more likely.

Stating the obvious since 1969.

Try it (none / 1) (#60)
by Sgt York on Wed Oct 03, 2007 at 03:48:20 PM EST

Give it a shot & see how much DNA is in it. Amount of DNA/g (or mL) of food.

We normally measure DNA by absorbance at 260nm, but I doubt many of you have a home spec. You could also put the glob of precipitated DNA on a scale, but we'd be talking mg to g range here. A postal scale might work, but I think the only people with scales that accurate are drug dealers.

Couple of ideas, off the top of my head:

Smear test. Take two pieces of glass and press the DNA blob between them. Draw a line around the spot and measure it's area.

Volume test. Get a thin, clear tube. Affix a millimeter ruler. seal one end. Fill with rubbing alcohol to some line on the ruler. Put in the DNA glob and measure the displacement.

Neither one is really all that accurate, but a little more quantifiable than eyeballing it.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Damn interesting! +FP (none / 0) (#61)
by dakini on Wed Oct 03, 2007 at 04:11:26 PM EST



" May your vision be clear, your heart strong, and may you always follow your dreams."
What will I be looking at? (none / 0) (#68)
by DK4 Bloo on Thu Oct 04, 2007 at 06:36:18 PM EST

To my simple mind the visible strands are DNA strands. But DNA is not just simply visible like that is it? I mean...

You're looking at (3.00 / 2) (#77)
by Sgt York on Fri Oct 05, 2007 at 04:27:21 PM EST

DNA + salt. Imagine a really thin thread; so thin you can just barely see it if you know it's there. Now wad it up; it's visible. Eukaryotic genomic DNA may be nanometers wide, but the length is on the meter scale.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

If you understand DNA, I have a question for you (none / 0) (#72)
by Elija on Fri Oct 05, 2007 at 07:10:18 AM EST

How does genetic fingerprinting work on a sperm sample?

As I understand it, thanks to meiosis the DNA in a sperm cell is different from the DNA in any other cell: there has been crossing-over.


# of differences caused by crossings is small (none / 0) (#78)
by rpresser on Fri Oct 05, 2007 at 04:57:54 PM EST

compared to the number of instances where it will be unchanged relative to somatic cells.

Fingerprinting doesn't match whole strands against each other; it matches fairly long fragments.
------------
"In terms of both hyperbolic overreaching and eventual wrongness, the Permanent [Republican] Majority has set a new, and truly difficult to beat, standard." --rusty
[ Parent ]

Can you use hamburger? (none / 0) (#73)
by rpresser on Fri Oct 05, 2007 at 12:23:26 PM EST

Would think that meat would have lots of DNA.
------------
"In terms of both hyperbolic overreaching and eventual wrongness, the Permanent [Republican] Majority has set a new, and truly difficult to beat, standard." --rusty
Probably (none / 0) (#76)
by Sgt York on Fri Oct 05, 2007 at 04:24:29 PM EST

Just use more meat tenderizer; more protein in there.

Also, the strawberry will likely yield more DNA.

There is a reason for everything. Sometimes, that reason just sucks.
[ Parent ]

Reading after 36+ hours awake (none / 0) (#79)
by Prophet themusicgod1 on Thu Oct 18, 2007 at 09:53:52 PM EST

I read that as
* A strawberry
* Some powdered meat tenderizer, (parepin)
* Some liquid soap
* A fork
* Two small cups (shot glasses are great)
* A coffee filter
* Some rubbing alcohol

"I suspect the best way to deal with procrastination is to put off the procrastination itself until later. I've been meaning to try this, but haven't gotten around to it yet."swr
i think you've outgrown this site Sgt York (none / 0) (#80)
by zombie HollyHopDrive on Mon Nov 05, 2007 at 06:17:06 AM EST





[He blew]inside..m..e.. [and verily] corrected a deviated septum and cauterized my turbinates. - MichaelCrawford
FUN WITH FRUIT | 80 comments (52 topical, 28 editorial, 0 hidden)
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