Tuesday, May 2, 2017

Resurrection and Regeneration - Key to the Continuity of Life of Organisms

Dr Abe V Rotor
 Living with Nature - School on Blog

Field cricket (Acheta bimaculata) and sand crab can regenerate a lost leg or two, including the large hind legs, and pincers (crab).  Starfish when cut in half through the central disk will regenerate into two, each with complete arms .  

Old folks tell us of the magic of lizards growing new tails, crabs regaining lost claws, starfish arising from body pieces. How can we explain the mystery behind these stories?

The biological phenomenon behind these stories is called regeneration. 

The male deer grows a new set of anthers, and lose them after the mating season. Sea squirts and hydras are produced from tiny buds, so with yeast forming buds. This is the same way plants grow from cuttings, seaweeds grow from fragments, and algae from filaments. New worms may regenerate from just pieces of the body, and some fish can sprout new fins to replace the ones that have been bitten off.

Experiments demonstrated that the forelimb of a salamander severed midway between the elbow and the wrist, can actually grow into a new one exactly the same as the lost parts. The stump re-forms the missing forelimb, wrist, and digits within a few months.

In biology this is called redifferentiation, which means that the new tissues are capable of reproducing the actual structure and attendant function of the original tissues.

Studies on children who lose fingertips in accidents can regrow the tip of the digit provided their wounds are not sealed up with flaps of skin. They normally won't have a finger print, and if there is any piece of the finger nail left it will grow back as well, usually in a square shape rather than round.

Curious the kid I was, I examined a twitching piece of tail, without any trace of its owner. I was puzzled at what I saw. My father explained how the lizard, a skink or bubuli (alibut' Ilk), escaped its would-be predator by leaving its tail twitching to attract its enemy, while its tailless body stealthily went into hiding.

“It will grow a new tail,” father assured me. I have also witnessed tailless house lizards (butiki) growing back their tails at various stages, feeding on insects around a ceiling lamp. During the regeneration period these house lizards were not as agile as those with normal tails were, which led me to realize the importance of the tail.

Regeneration is a survival mechanism of many organisms. Even if you have successfully subdued a live crab you might end up holding only its pincers while the canny creature has gone back into the water. This is true also to grasshoppers; they escape by pulling away from their captors, leaving their large trapped hind legs behind. But soon, like their crustacean relatives, new appendages will start growing to replace the lost ones.

Another kind of regeneration is compensatory hypertrophy, a kind of temporary growth response that occurs in such organs as the liver and kidney when they are damaged. If a surgeon removes up to 70 percent of a diseased liver, the remaining liver tissues undergo rapid mitosis (multiplication of cells) until almost the original liver mass is restored. Similarly, if one kidney is removed, the other enlarges greatly to compensate for its lost partner.

Regeneration of the kidney is in the nephron, which is composed of the glomerulus, tubules, the collecting duct and peritubular capillaries. The regenerative capacity of the mammalian kidney however, is limited as compared to that of lower vertebrates.

How about the human skeleton? The ribs can regenerate with the periosteum, the membrane that surrounds the rib, is left intact. A research was conducted on rib material being used for skull reconstruction. In that particular operation, all 12 patients had complete regeneration of the resected rib. I would not however, relate this feat to Genesis on the theory of creation.

Organ transplantation in higher animals has thus succeeded extensively and is now a regular part in medical practice. Resurrecting the dead however, remains a mystery. Stories in the bible of the raising of Lazarus and the dead little girl remain a matter of faith.

Yet in our postmodern times, a hundred or so ultra rich people lie in cryonics tanks awaiting the time when science shall then have the power to resurrect them. Then there is a short cut to resurrection, so the movie Jurassic Park, make people believe - the reconstruction of the total organism from a piece of its DNA (deoxyribose nucleic acid).

Why such wide and varied aims of man? Not because of man's unending desire for wealth and power, but the belief that the living world has common answer to present day inquiries. For example, is vegetative reproduction limited to plants and protists, why not to mammals? Why are lichens older than most organisms, outliving them by years, if not centuries? Why is a single tissue capable of complete growth to form an entire organism, and that, from this organism another generation arises? If such is the case, then there is no real death of that organism after all. For is it not that life is a continuing process; the DNA is but a continuous stream from one generation to the next, ever young and vibrant, spreading into numbers we call population, and types we call diversity?

Then, if this is so, there is but a shade that separates regeneration and resurrection - or whatever terms we describe the continuity of life on earth.~

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