Not sure at all
I'm wondering if they really will help with determining the time of death.
If people have any of these zebrafish genes, maybe the time of death winds up being next Tuesday.
Or I'm overthinking it.
In one of the creepiest bits of science Vulture South has ever encountered, a US scientist has identified 1,000 genes that become active after death. Not just immediately post-mortem, either: some of the genes in question, found in zebrafish, remained active four days after the fish died (and in mice, they were active two days …
It makes sense to me. These genes would be active during development, but presumably during that development another gene comes along and turns them off (or else we would never stop growing).
If the death of the gene suppressing the development gene dies, and whilst there is still some energy left in the system, the development genes turn on again, but there isn't enough energy in the system to sustain the growth, so they end up dying too.
If we can identify the genes involved in the suppression, it could lead to things like limb re-regrowth, or spinal cord repair etc. - wow.
"These genes would be active during development, but presumably during that development another gene comes along and turns them off (or else we would never stop growing)."
Well gene expression and control is a lot more complicated than that. And some gene products are often involved in both development and normal adult function - the differential effect is often due to which tissues the expression continues in. It's really very, very complicated.
"It looks almost like genes making a last-ditch attempt to keep things going"
I agree with SRS that, rather than the genes being activated in an attempt to combat death, they become reactivated because the processes that suppresses their activity ceases; rather than an attempt to keep things going, it is a sign that things are terminally broken.
Hmm... now what does that remind me of?
Indeed - the empty car speeding past may be driving itself, or it may more simply have had brake failure on an incline.
The genetic code is hellaweird. e.g. There are probability-changing flags on the DNA spooling reels that govern which 'code' executes. One of them isn't so much "GOTO" as "don't not GOTO".
We're used to pushing a program along, because nothing otherwise happens. It's used to impeding and blocking things too, as there's no such thing for it as 'nothing otherwise happens' - it's a sea of competing chemical reactions.
"Things only get evolved away if they have a detrimental effect during the useful lifetime of the organism."
Why do you think these genes have a detrimental effect during the living phase of an organism ? As they seems to include "immune system, inflammation, and responses to stress." genes. Many of the others may be switched on due to a breakdown in control as happens in, for example, cancer.
"I think that was Geoff's point. There isn't so there is no selection pressure to shape post-mortem gene into anything useful."
He also said "These are probably just junk genes."
If they are "inflammatory, immune genes and responses to stress genes. " then they are essential not detrimental to the living phases
"If they are "inflammatory, immune genes and responses to stress genes. " then they are essential not detrimental to the living phases"
Exactly this. In the living organism cell death plays a very significant role in ,for starters, development. Apoptose is a major mechanism, and in the end individual cells die al the time and need to be recycled in the living organism.
It makes sense that there is a genetic mechanism that kicks in after cell death.
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