In my opinion, it’s an epiphany. A sense of achievement, or completion of your life. You’ve reached the end, there is no more, so it’s time to go, and go happy. Those that are ready to accept death are those who have a flash of insight that comforts them, and tells them it’s all right to go.
Some would view that as a religious experience, but I’m sure it’s purely psychological. A rationalisation.
Most people fear death right to the end. They don’t let go, it’s taken from them. That is a shame, but what can you do?
That’s why I say I’m looking forward to it. When it’s my time, I’ll go happily. Curiosity; adventure, or nothingness? Either way, there’s nothing to fear.
A friend of mine’s Mother went that way. She had cancer, and knew she was about to go. She went surrounded by her loved ones, with a smile on her face, and her last words were a comforting sense of being ready to go now.
I wanted to call Max on a point.
Dolly’s cells are equal in age to her mother’s and her own?
Qualify?
I have worked with cells from a woman called Henrietta Something. Any geneticists in here wil know her second name. She gave rise to the HeLal strain. Henrietta was a black woman who died sometime in the 20’s I believe. She lives on in labs across the world used in testing of various techniques. I have seen sheet and sheets of her skin being crown at the pasteur institute. The particular strain I was using for tested was known to have been contaminated but suited the purposes I needed them for.
All of these cells have one origin , they are of great age (even though their genesis is modern) and yet are still viable today. I wanted to ask Max if he though that aged cell strains suffer in some way and also how he maintaind that Dolly’s cells are older that might be expected.
As to wether or not cloning has taken place…well suffice it to say that one of the basic things I learned after just a year in college was how simple this is in practise. We had a practical lab where we esentially “cloned” bacterial cells…all you need is a little salt…a little alcohol , a centrifuge and an oven.That’s a long long way from what is required to clone a multicellular organism but if thats what they teach elementary students of the biological sciences I would be surprised if the expertise is very widespread.
Damhna, I’m not a geneticist but I know you’re talking about the cells of Henrietta Lacks.
Also, the post about Dolly and the age of her cells was mine, not Max’s.
What I meant about Dolly’s cells being the age of her plus her mother was this:
When a creature is born, its cells are programmed with the ability to divide and produce “daughter” cells a certain number of times. I think in humans it’s 100. After a given human’s cells have divided 100 times, they stop. So when you lose cells to any sort of damage, they’re no longer replaced.
Okay, so let’s assume just for argument’s sake that a sheep’s cells can divide 50 times in its lifetime (I don’t know the actual number). Let’s further assume that Dolly’s mother’s cells were halfway to senescence, and had divided 25 times.
Dolly was cloned from one of those cells. While she resembled any other healthy lamb at birth, her cells only had 25 divisions remaining to them instead of the 50 any other newborn lamb would have (again, I’m making up the numbers to grease the discussion).
Henrietta Lacks died of cancer, and the HeLa cells used in labs today are from her cancer. Cancerous cells are mutants, and one characteristic of their mutation is they don’t have any limits on their division like normal cells do. One of the challenges for immortalist researchers is to remove the natural limits on cell division without causing cancer. It’s a tough nut, but they get closer to solving it all the time.
That explains a lot of things that I really should have remembered.You’ve also neatly explained why all of HeLal is contaminated.
I wonder if your hardcoded limit is a fixed rule?
You say that it is a cellular limit , which meatly gets around the PCR problem…or does it?
I’m not familiar with the minutate of the technique used in Dolly’s genesis but I woul have imagined that it was genetic material that was inserted into a viable (neutral) egg?
If that is the case then the limitation is DNA related.
What then happens to the buckets of DNA you can factor up using PCR? Is it considered that this DNA having been replicated so many times is then null? How then are sufficent quantities manufactured for testing in this area.
I had more questions on stem and undifferentiated cells but I’ll wait to see your response on this much.
A little knowledge is a dangerous thing eh?
My professors would be ashamed of me ;(
The limitation is DNA related. I should’ve explained in my last post, but it was getting too long as it was.
Our chromosomes have little things on the end of them called telomeres. Picture them as being like the little things on the end of your shoelaces. The telomeres get shorter with each cell division, until eventually they’re gone entirely. Once the telomeres are gone, the cells no longer divide.
When a sperm and egg fuse, the newly-created organism has a fresh, restored set of telomeres…it’s not like the embryo is as old as its parents’ haploid cells. I don’t know why.
I’m pretty sure that in Dolly’s case the (diploid) nucleus from an adult sheep’s cell was placed in a fertile ovum from another female sheep. So she didn’t start off with a “fresh” set of telomeres.
There’s an enzyme called telomerase that is involved in this whole procedure somehow.
Once again, a disclaimer: I’m not a geneticist, biologist or any sort of scientist. I have a lay interest and all my knowledge comes from Scientific American and other such publications.
Just remember that my generation wanted to die before we got old and didn’t trust anyone over 30–placing a value on some kind of authenticity or spontaneity. Life has never been the sole good of any culture’s value system–honor, virtue, providing for one’s offspring, freedom–all of these have been deemed causes more important than death. Where is the honor in immortality devoid of meaning?
