How do cells suddenly create their little incinerators from scratch?
| February 17, 2012 | Posted by News under Cell biology, News |
autophagy in fruit fly larva/Neufeld, Scott, Nizushima
In “The Enigmatic Membrane” (The Scientist, February 1, 2012), Muriel Mari, Sharon A. Tooze, and Fulvio Reggiori report, “Despite years of research, the longstanding mystery of where the autophagosome gets its double lipid bilayers is not much clearer.” The autophagosome is a device inside a cell that chemically incinerates dead stuff, clutter and germs, producing fuel:
Cells live longer than their internal components. To keep their cytoplasm clear of excess or damaged organelles, as well as invading pathogens, or to feed themselves in time of nutrient deprivation, cells degrade these unwanted or potentially harmful structures, and produce needed food and fuel, using a process they have honed over millions of years. Known as autophagy, this catabolic process involves the selection and the sequestration of the targeted structures into unique transport vesicles called autophagosomes, which then deliver the contents to lysosomes where they are degraded by lytic enzymes. This conserved eukaryotic pathway plays a central role in a multitude of physiological processes, including programmed cell death, development, and differentiation.
[ ... ]
Despite significant advances over the last 20 years in the understanding of how this process works and what purposes it serves, there is a lingering question—how are autophagosomes formed? More specifically, where do their not one, but two lipid bilayers come from? Autophagosomes are not pre-built organelles that become active upon the induction of autophagy; they are made from scratch each time a cell needs to degrade one or more of its contents. And they are giant vesicles, with an average diameter of approximately 700–800 nanometers, which can further expand to accommodate large structures such as cellular organelles and bacteria, and which are made in large quantities under autophagy-inducing conditions. As a result, progression of autophagy requires a ready supply of lipids. This aspect of the process has intrigued researchers since the discovery of autophagy in the 1950s and ’60s. Understanding the biogenesis of autophagosomes will provide information about how cells generate new compartments in response to internal and external cues, and will thus lead to a clearer conception of cell homeostasis.
And much more.
The authors look at various possible sources of the essential membrane without much success. This looks like a promising area for design theorists. Especially because many diseases (“cardiovascular and autoimmune diseases, neuro- and myodegenerative disorders, and malignancies”) are linked to problems with cleaning up the cell. If we knew how the autophagosomes suddenly get made from scratch as needed, we might have a better idea how to make it happen more quickly or more often- when nature needs a nudge.
14 Responses to How do cells suddenly create their little incinerators from scratch?
Leave a Reply
You must be logged in to post a comment.
Yet another meaningless phrase added at random to give the required obeisance to god of chance.
I guess before this process was sufficiently honed cells just died faster.
No doubt the researchers are, even now, nailing down the precise evolutionary sequence.
Semi OT: A printer that prints complex 3-D parts;
OK Darwinists, is the machine a product of intelligent design or was it a product of random chance???
Intelligent design.
What are some things that are the product of random chance?
lastyearon you state in answer to the question,
OK, I’ll play along, why is the machine intelligently designed and yet the engineer, who is vastly more complex than the machine, who intelligently designed the machine, not intelligently designed??? Exactly what criteria did you use to infer intelligent design of the machine???
SCheesman, you have a wicked, wicked tongue. Each sentence is a gem.
Any thought of putting in my two penn’orth vanished as soon as I began reading your post.
Even the words, ‘nailing down the precise evolutionary sequence’ have a particularly ironic, hilariously ironic resonance for UDers. Lots of ‘probably’s, ‘must haves’ and ‘no doubt’s and ‘would have’s’. ‘Nail ‘em down’!!!
Incidentally, I’ve always thought it curious that those folk-singers should think it worthy of mention that they’d prefer to be a hammer than a nail. I doubt if even masochists would want to be the nail. Also, incidentally, and by sheer random chance, I have finally contributed something technical to this forum – even if it was just a hammer and a nail.
I think I must have been ‘in the zone’, conjecturing about evolution, when the inspiration crept up on me.
Semi OT:
On this episode of ID the Future, Casey Luskin interviews Dr. Donald E. Johnson about his 2010 book, Programming of Life, which compares the workings of biology to a computer.
Here is the video that goes with the ‘Programming Of Life’ book:
lastyearon @3:
“What are some things that are the product of random chance?”
The rocks strewn about my driveway, the leaves on the ground under the tree, the papers all over my desk and the floor. Oh, sure there is a non-random component in the sense that things are governed by the laws of physics. So we could have the age-old discussion about whether anything is truly random. Either way, it is in opposition to something that is designed, because the latter (i) has characteristics of design, and (ii) is not explainable solely by reference to chance and necessity.
lastyearon; you may appreciate this quote as to how people ‘automatically’ infer intelligent design:
Along that same line,,
On this episode of ID the Future, Casey Luskin interviews Dr. Donald E. Johnson about his 2010 book, Programming of Life, which compares the workings of biology to a computer.
Here is the video that goes with the ‘Programming Of Life’ book:
The pattern of leaves on my lawn.
The pattern of clouds in the sky.
The dust bunnies behind my computer desk.
The dust bunnies under my bed.
The rust on my old snow blower.
Sickle-celled anemia.
Well those are some things but by no means everything.
Perhaps people who ‘automatically’ see intelligent design in nature and in life are like the little children in this story who recognize something beautiful, as opposed to the adults in the story who are ‘too busy’ to recognize the treasure right before their eyes and ears::
semi OT:
Here is a list of some fairly good videos on the cell and on the molecular machines in the cell