Buzz, learn and lead- Chapter 3


Buzz, learn and lead!

A story in four chapters presenting the potential for a fast-forward in evolution through a guided tour

Chapter 3

Innate Immunity

“We have a lot in common, bees and humans, I mean.” announced Master the next morning, and neither Nari nor I showed our surprise at finding ourselves in our regular shapes on his matted head once again. We also had no idea where exactly the three of us had arrived. The landscape did not appear different. Plenty of birds, including terns were still in evidence. The communication, of course, was very silent as before and as effective as before. “You dance to communicate and so can we, though we have languages, these days,” he continued, “and both love to go out in search of food for ourselves and others, even when we do not feel hungry. You see, we have this herd instinct, social inclination, shall we call it? And we like to keep our houses clean, though these days some of us have got so busy making or collecting useless things, that hygiene in human society has become secondary. We both instinctively love warmth and stay in groups to keep warm or at least feel warm.”

Nari and I were wondering at the pause which followed, when he continued slowly, as if he wanted us to be sure to get the weight of his words. “My children, in the past three years, expert scientists in genetics around the world have been studying carefully the sequence of genomes in the genes of some well known insects, considered of importance to men, as providers, disease carriers or just good models for study. You came third after the fruit fly Drosophila and the malaria mosquito anopheles. Next in line are a flour eating beetle, an aphid and a wasp, I am told.”

We were informed further by Master that both bees and humans should have had a common ancestor some 6oo million years ago and that unlike the fruit fly or the mosquito which have also been studied to some extent, we the bees had been evolving more slowly, rather like mammals! This is supposed to have given us some 10,000 to 15,000 genes arrayed on 16 chromosomes, almost comparable to the 24,000 genes and 24 chromosomes of human beings. Some of our genes, the ones responsible for internal ‘clocks’ and circadian rhythms are believed to be more like the mammalian counterparts than like genes from flies. Master said jokingly that if we had not become fixed on honey, we could have become men or apes! But the point is, he observed, you did not and you chose to be insects instead, with a very necessary instinct for hygiene, because you live most of the time crowded indoors at a warm 94 degree Fahrenheit home. Some of us stay indoors all the time, not just most of the time, we reflected sombrely, and attended to what he wanted to teach us.

The world outside suddenly began to loom much larger and we knew that the three of us had become teeny weeny micro organisms, the only ones not reproducing in a colony of pathogens like us. Master said that we would tag along with the group, but would be able to reassemble finally. He bade us to be fully aware till our lessons from the group were over. The responsibility was his and we had nothing to worry. We were told that we were still on the same tree at Sultanpur, but had shifted from the tern’s body to the base of the tree first and then to the gooey flesh of a rotting fruit, on the tree. We felt we were in a viscous mire of sorts and instinctively felt like invading the body of an insect-monster that was happily perched on the fruit and tasting its pulp. Master informed us that the insect was a fruit fly of the family Drosophila melanogaster, which he told us had been the object of extensive and intensive studies in the recent past. Master also told us that Nari and I were rather different from each other in our pathogen-class, which he would explain to us later. Meanwhile he asked us to do whatever occurred to our minds and report to him whatever we experienced. He told us not to bother about any danger to us in the process, as we were continuously in his protection.

 

 

The normal fruit fly Drosophila melanogaster

Presently I lost track of Master and Nari and found myself in a mass of pathogens exactly like me. Some of us went into the fly as he gobbled a bit of the spoiled fruit and we quickly reached what most certainly was his intestine, a winding tunnel, whose walls were our instinctive target. We were, however thwarted by a membrane barrier, which Master would later tell us as being made of a substance called chitin, from entering the intestinal epithelium. It was uncanny, and we felt that the membrane knew exactly who was attacking it. As our numbers grew, however, some of us managed to get in and were immediately swamped by an army of some species, clearly confirming that our identity was only too well known. I passed out and came to my senses only to find that Master, Nari and I were alone again on another part of the fruit, well away from the mouth of the fly.

The account given by Nari to Master was exactly like mine, except that in describing the features of the structure that attacked her, Nari differed a little in detail from the account of the adversary whom I faced. This had to be so, because Nari did not resemble me in detail. She resembled Master, however, and asked him whether he had accompanied her. Master smiled and said no, but that he had gone in separately inside to pick up whatever remained of the two of us and bring the stuff out for the sake of formally reviving us to our latest incarnations. When Master asked whether the things that successfully fought with us were discreet creatures like ourselves, we could not answer him satisfactorily.

Master said that scientists even now are not quite aware what the natural bacterial enemies of this kind of Drosophila were. However, they had recently worked both on the insect itself and its larvae, by inserting known microbes using very thin needles. Even in experiments when a microbe was ingested into the midguts of larvae rather than the flies themselves, they found the effectiveness of the chitin membrane barrier. Such injections caused injuries and were not the most satisfactory procedure for induced infection of the fly or the larvae, but the scientists got some very definite clues. Apart from evidence of the chitin barrier, they learnt that depending on the nature of the ingested pathogen, expression or pushing out of suitable antibody genes occurred from the body of the host. The peptide structures encoded by the genes could be analysed and were found to be antifungal or antibacterial depending on whether a microbial fungus was ingested or whether natural bacterial infection took place. The kind of bacteria also determined the nature of the genes expressed.

Master confided that he and Nari had become members of an entomopathogenic fungal species, whatever that may mean. To attack Nari, the immune mechanism in the fruit fly’s intestine had projected or expressed from the intestinal wall material genes of the drosomycin variety, with encoded peptides having antifungal properties. The genes that came for me and my kind, a gram-negative bacteria, from the intestinal wall of the Drosophila had encoded peptides with decided antibacterial characteristics and were known to be of the diptericin variety, Master told us. Because of its excellent capacity for identifying the invading pathogen or equivalent material the correct fighter genes were expressed always. Sometimes they were one kind and sometimes both kinds. The defence also included encapsulation, melanisation and coagulation of enemy depending on type and size.

‘Rani and Nari, your hardworking species has settled in the course of its evolution to the option of a clean environment to keep disease-micro-organisms out of reckoning.

Your evolution did not take into account the possibility and desirability of strong natural immunity against unfriendly pathogens and the resultant irrelevance of hygiene and the tough housekeeping it involves. In the millions of years since you perfected the symphony of your existence, there has however been an explosive increase in the complexity and numbers of unfriendly micro-organisms, which have affected the safety and cleanliness of all living spaces including yours. You may need to reconsider the sanctity of hygiene above natural immunity, I am afraid.’

We listened as we were given this silent capsule for thought and decided that we were sleepy. Tomorrow was sure to bring in more nuggets of wisdom. But even as we were dropping off, Master’s parting message of the day was sinking clearly and deliberately into us.

· With excellent hygiene at home, you may keep a large number of unfriendly pathogens out most of the time, but not all possible pathogens all the time.

· Some of you get out and get back home and this can affect hygiene adversely some of the time.

· If you have strong natural defences, you can manage such aberrations easily.

· In fact, it should be possible to build natural immunities to such an extent that hygiene may appear irrelevant.

· Human society has very rich experience and records of the superiority of natural or induced internal immunity over external disinfection.

· Sage Valmiki would have pointed out to you the resourcefulness of his hero, Rama, whose balam or strength had several components to it, like courage, stability, valour, ability to use fighting skills, inbuilt fighting prowess and willingness to do his heroic best during fight.

· The natural immunity of the houseflies is like Rama’s inbuilt fighting prowess.

· It is more effective than the confidence available from external props such as weapons. These flies had their weaponry too, but strictly as part of their natural immunity system.

 

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