Here ya go, Unc. This quote is from one of our past lengthy discussion threads. The opening statement is mine.
WE do not "set the hair" with our actions.
WE do not make leather fibers. They are already made.
I feel better already, just writing that.
Skin cells ride on top of the fibers (collagen). The white pickled flesh side of the hide is the fibers.
Almost everyone reading this will be familiar with a whitetail skin. The ACTUAL cell layer will be just a tiny bit thicker than the length of a mature hair follicle.
I have pulled a thread from the old archives that to be so brief is a pretty classic piece of work.
If you didn't hear colorful words like these at the last party you went to, you need some different drinking buddies.
If you don't know the meaning of these words, you're going to have a hard time following and understanding this thread. Google and ye shall gain the truth and wisdom that thou seeketh. (The later it gets, the worse I get.)
REMEMBER as you read this, this is dealing with the cellular level, or cellular depth/thickness of the skin, and the fluids are being drawn with salt through the fiber layer.
Salting and its effect on cellular material
Submitted by Yoshan Moodley on 05/15/2003. ( email@example.com
<mailto:firstname.lastname@example.org> <Mailto:email@example.com> ) 220.127.116.11
I have been prompted to add this to the Taxidermy.net forum. I am sure that most of you are aware of most of this, but please read further if you think that this may be of interest to you.
When an animal is skinned and fleshed in the field, the best way to preserve its skin is to liberally apply rough salt (Sodium Chloride) to it and leave it to dry. Salt acts as a dehydrator and absorbs moisture (or [cytosolic fluid/color]) from the skin ([/epithelialcolor]) cells, markedly speeding up the drying process. It this rapid dehydration of cytosolic fluid that enables the epithelial skin cells to retain much of their intracellular organelles such as nuclei and mitochondria. If skin was simply left out to dry in the sun without the application of salt, then there would be enough time for the degradation of cellular material by proteases and lysozymes housed within the cell. If, on the other hand, the skin dried quickly enough to beat this degradation, the heat required to dry it this quickly would end up causing a similar amount of organelle and structural (cytoskeletal) damage.
So, you see, there is no getting away from it, salting is the best way to preserve skins in the field. The quality of salt used may sometimes cause problems with the quality of the skins after tanning and it is always important that your clients make sure that the salt they use is first grade.
From a DNA perspective, dry-salted skin harbours a gold mine of epithelial skin cells, each with more or less intact nuclei and mitochondria - the two organelles that harbour all our DNA. This is why we require only a small piece of skin for DNA studies. When we receive the skin piece we incubate it in an isotonic solution with 1% sodium dodecyl sulphate (SDS) and about 200ug/ml of proteinase. SDS is a powerful detergent which lyses the cell membrane which is made of fats or lipids. Then the proteinase chomps up the proteins of the cell indiscriminately, releasing the DNA molecules from the nucleus and mitochondria.
We then apply phenol to get rid of the protein debris and separate these from the aqueous liquid which should by now contain just the DNA in solution. It is as simple as that!
Every now and then we receive pieces of skin from animals that have died in the veld and have decomposed naturally. The hard skin, with cells completely degraded, may still house DNA, but without the protection of the cytoskeleton and the nucleus, this DNA has been broken up into very small pieces by the action of UV radiation from the sun. Luckily technology is of such a standard these days that we can even make use of this degraded DNA in genetics, although much more effort must be applied in order to get these samples to work in the lab.
The most tragic element of taxidermy and museum curation is the tanning of skins. When this happens, the cellular and biological elements of the epithelial cells are replaced by chemical ones. The skin is virtually DNA free and is useless for any genetic or forensic investigations. It is unfortunate that tanned skins look and feel so much nicer than dry-salted ones and I do not blame taxidermists one bit for preferring to work with skins in this form.
I thank you for reading through this and hope that it has been of some help.
I have a number of skin micro photography photographs floating around in here. Thing is, I have no idea as to where they are all at. I tend to respond to some of these posts in a spontaneous fashion if I already have the photos on file. There is one that I did remember the title of the thread, and found it using Google's main index.http://www.taxidermy.net/forum/index.php?topic=1558.0