Sunday, August 17, 2008


Biotechnology and Society---Part XV

wonderful! O wonderful! O wonderful!
I am food! I am food! I am food!
I eat food! I eat food! I eat food!
My name never dies, never dies, never dies!
I was born first in the first of the worlds, earlier than the gods, in the belly of what has no death!
Whoever gives me away has helped me the most!
I, who am food, eat the eater of food!
I have overcome this world!

He who knows this shines like the sun.
Such are the laws of the mystery!

Amity and enmity are normally considered the affections of only animate beings high on the evolutionary scale. Not exactly true. Inanimate objects like atoms do have their own likes and dislikes. For example, the sodium atom would love to mate with a chlorine atom with a voracious appetite to form sodium chloride, known as common salt. The same sodium atom also knows how to co-exist with its own kind. Among animate beings, even bacteria, lowest on the totem pole of living creatures, display deep emotions and a sense of togetherness when needed. Among humans, we witness cooperation as well as isolation as characteristics among individuals according to the dictates of circumstances. Among lower species such as animals and insects, cooperation is widely prevalent among one’s own kind of species. Did sociality and cooperation originate with the primitive forms of life? Let us take a look at the social life of bacteria and what we can learn from that. Researchers have recently discovered that tiny worms from a particular strain of C. elegans, do not like to eat alone. When placed near food (a patch of bacteria in a gel medium) they scurry around looking for company. Worms of another strain of C. elegans clearly prefer solitude. Should we care about the social life of a tiny worm? Perhaps, yes, mainly because we may have similar genes that dictate such behaviour. The sociable worms were found to move around the food plate rapidly, not slowing down until they found some eating companions. By contrast the anti-social worms moved very slowly all the time grazing on food right from the start. When their DNAs were analysed, it appeared that the difference amounted to one codon (a triplet of nucleotides), resulting in one amino acid being different in a single protein between the two classes. What a precise division of classes!

Bacteria are so ubiquitous that they are found on mountaintops, ocean bottoms, guts of animals, hot springs and the Antarctic ice shelves. The ecosystem, on land as well as water, depends on bacterial activity. The cycling of carbon, nitrogen, and sulphur is completed by their tireless labour. When organisms die, the carbon in their tissues is not available for most other living beings. Bacteria break them down and release the nutrients to the environment. Plants rely on nitrogen from the soil for growth and to make proteins. Only the soil bacteria which coexist with the root system of plants make the gaseous nitrogen in the atmosphere available to the plant in the form of soluble nitrogen.

Bacteria (born blind, deaf and mute) communicate with each other (just like cells in our human body 'talk' to each other) through chemical signals as if they are veritable social organisms. Many of them coexist in colonies which are known as biofilms. When they do so they can protect themselves against antibiotics and become resistant to other chemicals. They know the maxim, 'United, we stand'. In a colony all the bacteria may produce byproducts not for themselves but simply to promote the welfare of the colony, i.e., to help their brethren. Adapting to maximise exposure to air and nutrient-rich medium is difficult for individual bacteria. In a colony it is a cooperative venture.In the case of Pseudomonas fluorescens, mutation allows them to make a polymer glue so that they can stick together and form a film or mat. Each bacterium incurs a cost in producing the glue which is neither useful for its own growth nor cell division but the group as a whole benefits. Here we see a selection level where they sacrifice some of their individual needs while contributing to the group. In this case, it is the fittest group that survives, and not necessarily the fittest individuals. However, this social tendency can rapidly degrade if they happen to be in an asocial environment, like a homogeneous liquid culture medium. How far do the bacteria go in promoting sociality? Some researchers think that individual bacteria would even die to keep the colony alive. It appears that if some bacterial cells are damaged by antibiotics they commit suicide so that the rest of the colony can live. By killing themselves, the damaged cells no longer burden the colony but their remnants provide needed nutrients for their kin and neighbours. However, not all the bacteria in a colony commit suicide upon confronting a massive dose of antibiotic. They shut down the cellular suicide mechanism since it does not serve any purpose if all of them die. Cells of a species called Bacillus subtilis, when faced with starvation, compact themselves and become dormant creatures called spores at which state they can stay alive for an indefinite period. It is similar to the hibernation behaviour of bears. Here again sociality is seen. When encountering starvation the cells align themselves to form multi-cellular structures. The interior cells develop into spores, which can remain dormant for hundreds of years. Here we see again a display of cooperation. Sometimes they commit cannibalism during starvation. In other words, they kill their neighbours in order to survive by utilising the remnants of the dead bacteria. Although cannibalism appears, prima facie, a destructive behaviour, it happens for the good of the species. As with cell suicide, cannibalism is ultimately beneficial for the population as a whole, since it delays or prevents sporulation for the entire population, which is only a last resort under extreme conditions.

Click here for big picture

Networking: This cooperation signifies a networking principle. What one bacterium cannot achieve individually, it will achieve in conjunction with a multitude of its kind. This concept is the forerunner for the modern network theory of information processing using multiple computers and parallel processing. Pristine bacteria mastered the art of universal information exchange.

As life forms became more complex, they became less directly dependent on each other for survival. They developed mimicry for transmitting knowledge. By observing their peer organisms they learnt how to handle emergent situations. It is not strictly cooperation but mutual learning. In the insect world, colonies of individual organisms appear to exhibit powers not displayed by individual insects. Such coordinated function has probably evolved from the colony-forming tendency of bacteria.

What can we learn from the sociality of bacteria and other forms of life on the evolutionary scale? Knowledge sharing and communication are important for survival. The behavioural dynamics of the human population indicates a connection to earlier patterns of communication and knowledge-sharing evident in every species tracing back to the earliest forms of life on this planet. However, as we noticed with some colonies of bacteria where they resort to cannibalism, we notice it among humans too but the end result is not the same. In the bacterial world it was for the survival of the group. In the human world it is for the survival of the individual. Did the 'selfless' gene mutate along the evolutionary pathway?

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