Threatening Proportions of Myopia

“World has become myopic,” is a colloquial trite. But believe it or not, the situation is really alarming. A recently published article in Nature reported that East Asian countries are afflicted by threatening proportions of myopia or short-sightedness, the inability to see objects at longer distances. In China up to 90% of the teenagers are myopic and figures even disturbing for Seoul where it is 96.5%. While immediate course corrections like glasses, contact lenses and surgery can offer relief but a worst case of short sight can increase risk of cataract, retinal detachment, glaucoma and even blindness.

Myopic condition is the fall of out of the slightly elongated eyeball which causes the lens to focus light away from the object leading to formation of image in front of retina instead of direct image formation on the retina. This condition occurs most commonly in school going kids and adolescents. It is reported that nearly one-fifth of the college going kids in East Asia have an extreme form of myopia and half of them are at the risk of developing irreversible vision loss.  The burgeoning threat of myopia has propelled scientists across the world to address this issue.

Myopia was believed to be the domain of book-worms who were considered to be more prone to this defect. Famous German astronomer Johannes Kepler attributed his short-sightedness to book work. For long even ophthalmologists too believed in the same dogma. By 1960 scientists believed that it is genetically transferred as it is common in genetically identical twins than non-identical twins. Genome analysis showed that 100 regions are responsible for myopia. Increasing cases of myopia among school children in East Asian countries has been linked to enhanced educational performance where in students spend long hours before books. Researchers too have drawn an association between academic performance and the number of hours of study. On average while a Chinese teenager spends 15 hours a week on homework against 5 hrs in UK and 6 hrs in USA. Moreover with teenagers becoming addicted to televisions and hooked onto smart phones eternally, the incidence has peaked.

Documented research reports began to throw light on the deleterious effects of sustained close work capable of affecting the growth of eye ball. Scientists at the Ohio State University, College of Optometry Columbus showed that bright light is protective to eye. The research hypothesis showed that bright light stimulates release of dopamine neurotransmitter in the retina blocking the elongation of eye. Diurnal cycle of eye is strongly controlled by bright light wherein retinal dopamine turns on the cone-based vision during the day and rod-based vision at night in response to the dim light. For people working in the dim light or indoors this cycle is messed up resulting in elongation of the retina.

Research conducted by the Australian National University estimated that children need to spend a minimum of three hours of day under the light intensity of 10,000 lux to be guarded against myopia (an over-cast day provides 10,000 lux against 500 lux of class room). Consequently three hours of outdoor activity has become a norm in Australia. Now schools in China and Taiwan are making way for 3 hrs of outdoor time in the school schedule.  Preliminary findings in those schools are promising. Schools which have relatively inflexible routine are contemplating to conduct classes in rooms fitted with glass to compensate for the outdoor time. An unpublished research also indicated that as the amount of time spent increased the incidence began to lessen. Thus, three hours of outdoor time not only improves the physical well being of the children but protects them against myopia.

In the meanwhile researchers are working on special glasses and contact lenses that can alter the eye growth by focusing light from distant objects at different angles rather than just at the centre as the regular glasses do. To curtail myopic progression regular use of eye drops with a neurotransmitter-blocking drug atropine at night is also recommended. A hand book of Ophthalmic Science and practice authored by Henry Edward Juler in 1904 mentioned that myopic is stationary; change of air- or possibly a sea voyage was prescribed. It ‘as been more than hundred years it took a swarm of brilliant brains with years of dedicated research and sophisticated inventory to confirm the intuitive thinking of yesteryears. 

 

 

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Horizontal Gene Transfer in Humans

For the past few decades genetically modified (GM) crops across the World were meted with lot of resistance from green activists. Wide spread campaigns strongly denounced GM crops as monster crops. They enunciated that their cultivation would destroy the traditional agriculture and decimate human race. The pseudo-science and superstition has resulted in curbing of field trials in India. The uproar and activism against these crops pressurised the government to act against the GM crops. While several acres of land is under the cultivation of GM crops in the US but the Europe shied away from its cultivation and enforced a strict ban on all the GM crops products. Research carried out by scientists in Cambridge University shed new light on the gene transfers annihilating fears about the cultivation of GM crops.

Fundamentally genes or the hereditary material DNA is transmitted from parents to the offspring directly through vertical gene transfer. There are reported instances of alternative mechanisms of gene transfer, know as horizontal gene transfer or lateral gene transfer reported in bacteria and unicellular eukaryotes. Existence of such mechanism is not established in higher organisms like vertebrates and least known in humans. Against this back ground, the research article published in Genome Biology by Alistair Crisp and Chiara Boschetti made startling observations indicating that humans have obtained 145 genes from their ancestors. Though it is much less than 1% of 20,000 human genes it is surprising to learn that human have obtained genes from lower organisms like flies, nematodes, fungus, plants and bacteria. The classical example of Drosophila obtaining more than 1Mb of genome from Wolbachia, a bacterium indicates that HGT is very common in lower organisms.

HGT involves transfer of the genetic material between different organisms and this process has played a crucial role in acquiring antibiotic resistance in bacteria. Genes obtained by HGT are mostly associated with metabolism and code for enzymatic activity suggesting that the process contributes to biochemical diversification. Computational analysis of transcriptomes of 40 different species carried out in this paper concluded that HGT occurs at low but in appreciable levels across all animal species. It has occurred over a period of time and still continues to occur and that it originated from bacteria and Prostists. In spite of structural complexities, research shows that overall levels of HGT are not conspicuously different between vertebrates and invertebrates.

While analysing the transcriptomes (data base of the mRNAs) comparison with immediate relatives is avoided. Flies are not compared to arthropods similarly no vertebrates with primates and no nematodes with worms. The results yielded that worms had 173 HGT genes, flies 40 and primates 109. It is interesting to learn that the genes responsible for the ABO antigen system which is the basis for blood groups is bacterial in origin and the genes involved in the synthesis of the hyaluronic acid, is from fungi and the gene associated with obesity has migrated from marine algae suggesting that gene insertions played a vital role during the process of evolution.

The human genome deciphered in 2000 also suggested the presence of plant genes. But it raised severe flak from critics who enunciated alternate theories to account for those genes to gene loss, convergent or divergent evolution. Researchers now comprehend that 1% of human genome might have immigrant from different species. Scientists who are attempting to create GM crops are just invoking the process that happened in nature over a period of time. During the course of evolution, foreign genes integrated into humans which slowly began to cohabit with its genome. Activists are now rallying behind the point that natural gene transfers took place over centuries. But it has to be borne in mind that even during the natural transfers, these genes were as align as the Bt gene insertion into cotton or brinjal. In fact scientists are simply replicating the process of natural gene transfer in a controlled environment in the laboratories to obtain GM crops. To ensure complete integration of foreign gene, scientists grow these crops under strict supervision and protected environment before releasing it for commercial use. Strict regulations and checks are in place to ensure minimal gene contamination and release into the environment.

This robust research now strongly questions the stand point of the green activists who demand complete annulment of GM crops. Besides allaying the fears of common man, the paper mocks at the frivolous scientific guidelines patronised by the antagonists of GM crops.

Dark Matter may have caused the extinction of Dinosaurs

It is estimated that more than 99% of the species that lived on the Earth are extinct today owing to the competition or inability to survive and others might have perished due to periodic cataclysmic events. New York University Biology Professor Micheal Rampino in his recent research article published in the Monthly Notices of the Royal Astronomical Society suggested that astrophysical findings could help us in understanding the biological phenomena occurring on the Earth. Fossil records show that Earth experienced periodic mass extinction cycles of 26-30 Million years over the past 250 Million year cycle. All these cataclysmic events are fall outs of collisions of either asteroids or comets and extended periods of volcanic emissions. The extinction of dinosaurs, 66 million years ago is one such most extensively researched events. Palaeontologists recognise five such humongous events wherein 90% of species were lost. Though there is an ambiguity over the periodicity of the events, the new postulates suggest that Cometary collisions might  have been triggered by the gravitational disruption of the Oort Cloud, where a repository of Comets reside in the outer edge of our solar system.

Every 250 million years the Sun with its entourage of planets makes a peregrination of our Milky Way. While orbiting, Solar System oscillates up and down through the galactic disc where the Galaxy’s dark matter is concentrated. During this process the Earth too passes through the galactic disc once in every 30 million years. Galactic disc is crowded with stars, clouds, dust and elusive sub-atomic particles whose existence can be detected by their gravitational effects. In this paper Prof. Rampino tries to shed light on the impact of the dark matter in the galactic disc on the periodicity of the terrestrial events. Interestingly the periods of gravitational effects of the dark matter on the Earth were found to be in congruent with the galactic dynamics.

Earlier he postulated Shiva Hypothesis named after Lord Shiva the God of destruction to explain how mass extinctions are caused by impact events. The hypothesis suggests that the gravitational disturbances are caused as the solar system crosses the plane of the Milky Way galaxy disturbing the comets in the Oort cloud surrounding the solar system. This results in raining of comets towards the inner solar system causing the impact. These impact events that occurred every 30 million years might have led to the cretaceous- paleogene extinction event.

While the composition of the dark matter is unknown, it is known to interact with visible matter and radiation under the influence of gravity. Modern theories suggest that dark matter is accounts for 23% of all mass in the universe, 73% of Universe is dark energy and the rest 4% includes regular matter such as planets, stars and people. The dark matter tends to interact with the regular matter as Earth passes through the galactic disc and eventually results in the disruption of Oort Cloud. The gravitational attraction between the dark matter and Earth will result in the accumulation of the dark matter at Earth’s core.

Rampino believes that as the dark matter particles build up, the particles will annihilate each other and release large amounts of energy. Approximately as earth passes through the galactic plane every 30 million years, internal heating of the Earth brings about massive changes in the Earth’s magnetic field, leads to cataclysmic events like tectonic shifting, eruption of volcanoes, rise of sea levels and climate.

Another study carried out by Harvard University team of theoretical physicists Rendall and Reece in their paper published in Physical Review Letters opined that dark matter is the source of the periodic Oort Cloud perturbation. Rampino believes that Earth’s cyclical movement through the thin, invisible, disc of dark matter would also lead to perturbations in the orbits of distant comets and results in heating up of Earth’s core. Thus the Cometary collisions and eruption of volcanoes might have led to the periodic mass extinction. The  astrophysical events caused by the oscillation of Earth around the galactic disc , results in consequent accumulation of the dark matter within the Earth’s core causing dramatic changes in the geological and biological phenomena on the Earth.

This model in fact opens up new vistas for understanding the impact of the astrophysical events on other planets in our solar system. It throws up new challenges for astrophysicists to extensively work on the excruciating details of the dark matter, whose composition is not yet clearly known. While the exact details of the sequence of events elucidated in the model are not scientifically worked out, it has eclectically linked the cycles of geological and biological evolution on the Earth to the rhythms of the Galactic dynamics.

 

 

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