World DNA Day falls on 25 April:

On 25 April 1953, Watson and Crick published an article, in the acclaimed journal “Nature” titled “Molecular structure of nucleic acids: A structure for deoxyribonucleic acid”.

The one-page article largely based on theoretical arguments and the previous work of Rosalind Franklin who examined DNA using X-rays, changed the world forever by explaining how genetic information is copied and transmitted.

Everyone concerned with promoting science in the country should be aware of the story behind the discovery of DNA and tell it to their children and students and remind the policymakers.

The world commemorates the transformative event on 25^th April every year. An example vividly illustrates how intense curiosity and imagination, rather than mere indulgence in technologies, leads to groundbreaking discoveries.

DNA Day is also intended to celebrate the completion of the Human Genome Project in 2003. Genome means the entire set of genetic information characterising an organism.

Heredity and inheritance

Heredity is the cause of transferring traits from parents to their offspring. The closely related word “inheritance “refers to the specific nature of the transmitted trait. For example, we say intelligence is hereditary in their family and he inherited his father’s intelligence.

The resemblance of progeny to parentage was common knowledge, taken for granted and considered a blending of maternal and paternal traits. Philosophers of antiquity proposed several theories to explain the inheritance of parental traits by the offspring. Hippocrates believed the essence of all body parts of the parents are incorporated into the male and female germinal essence and therefore the offspring display characteristics as a proportionate blend. Aristotle offered a different explanation. He argued that the active principle is in the male seminal fluid and the mother’s blood provided the original body material. The inaccuracy of these theories was apparent. Sometimes children possess qualities akin to grandparents rather than parents. Fathers or mothers of humans and animals, deformed by accidents or disease, gave birth to normal children- a clear proof that the acquired characters are not inherited. Children of a blue-eyed mother and a brown-eyed father have either blue or brown eyes but not a blend of blue and brown.

Two golden sayings in our culture, “Arae gathi nare” and “Jammeta wada lokuei purrudha” (“Hereditary characters persist” and “Habits overtake heredity “), agree more with modern genetics, than the views of Hippocrates and Aristotle.

Gregor Mendal’s groundbreaking experiment

The Austrian mathematician cum botanist, Gregor Mendel was the first to conduct a systematic investigation to understand the cause of heredity. Being unconvinced of the traditional explanations, he carried out a series of experiments lasting eight years to determine how the traits (plant height, seed color, flower color etc.) of pea plants are transmitted from generation to generation. When Mendel cross pollinated tall and short plants, he found that the progeny was entirely tall. However, when first generation tall plants were allowed to self-pollinate, the missing short trait reappeared at a statistically significant probability of 25 percent. Mendel’s work provided an unequivocal proof that traits do not blend but exist as unique entities, manifested from generation to generation following a predictable mathematical pattern.

Mendel’s finding remained unrecognized for more than 30 years. His ideas were too far ahead of time and biologists were shy of mathematics. In the early 1900s several European botanists arrived at the same conclusion based on independent experiments. With the advancement of microscopy, a great deal of information about plant and animal cells was gathered. A key finding was the presence of colored bodies in the cell nucleus named chromosomes, seen separating during cell division, leading to the hypothesis that Mendel’s genetic units (genes) should be physical entities present in the chromosomes.

Chemists and biologists wondered what the genetic material in chromosomes made off. Is it a protein, carbohydrate or a lipid? Most biological materials are constituted of these substances.

Discovery of DNA

Great discoveries are made by unusual people. The Swiss Friedrich Miescher belonged to a clan of reputed physicians. Following family tradition, he qualified as a doctor but did not engage in profitable practice of medicine. He decided to do research to understand the foundations of life. In search for new biological substances, he experimented with pus deposited in bandages and extracted a substance rich in phosphates but very different from proteins. The new substance called “nuclein” was indeed DNA. Later, the German biochemist Albrecht Kossel following the Miescher’s work, showed that DNA contains four crucial compounds, adenine (A), cytosine (C), guanine (G) and thymine (T), known as nucleotide bases.

Avery – MacLeod – McCarthy Experiment

The flu pandemic of 1918 killed an estimated 50 million people worldwide due to the pneumonia that followed the viral infection. Pneumonia was caused by the virulent bacterium Streptococcus pneumoniae. The British bacteriologist, Frederick Griffith attempting to find a vaccine for pneumonia, worked with two strains of Streptococcus pneumoniae, one virulent causing pneumonia in mice, and the other avirulent to them. He found that neither the virulent strain denatured by heating nor the live avirulent strain injected into mice caused the disease, whereas a mixture of the denatured virulent strain and the live avirulent strain was deadly to mice just as the virulent one. He concluded that some chemical compound present in the virulent strain – a transforming principle – has changed the avirulent strain to the virulent strain.

In 1944, Oswald Avery, Colin MacLeod and Maclyn McCarty working at the Rockefeller University, United States, continued the work of Frederick Griffith to identify the transferring principle and found that it is not protein as widely believed, but deoxyribonucleic acid (DNA). Their result pointed to the conclusion that DNA is the carrier of genetic information.

A book by a physicist that triggered a transformation in biology

The insights of brilliant brains engaged in fundamental inquiry have opened the way for major scientific discoveries and technological innovations. In 1944, the Austrian theoretical physicist Erwin Schrodinger, one of the founders of quantum mechanics, published a book titled “What is life? The physical aspect of the living cell “. The American biologist Maurice Wilkins said he was so inspired by Schrodinger’s book and after reading it, he decided to switch from ornithology to genetics. While physicist Maurice was influenced to take up biology. Francis Crick was a physicist working on magnetic mines for the British Admiralty during the war. After reading “What is life” he thought a physicist could find treasures in biology and joined the Cavendish Laboratory in Cambridge to pursue a Ph.D.

Structure of the DNA molecule

When DNA was shown to be the molecular entity that encodes genetic information, chemists rushed to determine its structure.

The pattern formed when X-rays passing through a material cast an image on a screen, provides information about its molecular structure. In 1938, the English physicist William Astbury examined DNA using x-rays and concluded that the molecule has a helical structure. Having heard a group in the United Kingdom was attempting to unearth the structure of DNA, the American theoretical chemist, Linus Pauling, adopted Astbury’s data and proposed a model for the structure of DNA, publishing the results in the journal “Nature” in January 1953.

There was an obscure but remarkably talented person, Rosalind Franklin, pursuing x-ray diffraction studies on DNA at King’s College London. After a painstaking effort, she obtained accurate x-ray diffraction images of DNA. Her colleague, Maurice Wilkins, working in the same laboratory, passed the images to Francis Crick and James Watson at Cavendish Laboratory.

Crick and Watson were more insightful and theoretical in their approach to elucidating the structure of DNA. They, inspired by Erwin Schrodinger’s hypothesis, that the entity accounting for heredity should be an aperiodic molecular entity in cells, arrived at the double helix model, showing that Linus Pauling’s model was erroneous. The Crick – Watson model explained how DNA stores information and replicates during cell division. Their assertions were subsequently confirmed rigorously by experimentation. Crick, Watson and Wilkins received the Nobel Prize for Physiology and Medicine in 1962.

The work following the Crick – Watson model, firmly established that the DNA is a polymer string constituted of two strands made of a sugar- phosphate backbone, connected to each other by linkage nucleotide bases A, T, G, C. The base A links base T and G to C. When one strand is defined by the arrangement of bases, the complementary strand is defined. The arrangement bases store information analogously to a four-letter alphabet. Each individual in a species has a unique sequence of arrangement base pairs. The variation within the species is generally a fraction of a percent.

The Watson-Crick model also explained how the DNA molecule replicates. The two strands unwind and separate, and two complementary strands are inserted. The detailed dynamics of the replication process are not fully understood.

‘DNA is a cookbook’

DNA functions like a multiple – volume cookbook, written in a four-letter alphabet. The volumes are kept in a rack in the kitchen. The rack is the nucleus and volumes on it are the chromosomes, and the cell is the kitchen. A paragraph giving a recipe is a gene. Enzymes act as chefs, who read recipes and give instructions to cell machinery to prepare the dishes, which are proteins. The system is so complex; a complete macroscopic analogy would be impossible.

The significance of the Crick- Watson work

Until Charles Darwin proposed the idea of evolution, biology lacked a theoretical foundation. Darwin hypothesized, when organisms reproduce, the progeny inherit parental characters, but there are variations. The variants, though similar to the parents, have some new or altered characters. If these characters, originating from mutations or cross – breeding are favorable for survival in the environment, they dominate in the population, inheriting advantageous traits. Thus, random generation – to – generation, advancements of living organisms, become possible – a way of improving the design of things in a production process without a designer. Living systems store information and progeny retrieve them, when required. A bird hatched from an egg when matured, knows how to fly.

The discovery of DNA and understanding how it stores genetic information, replicates and mutates explained Darwinian evolution. A mutation is a change in the ordering of base pairs, accidentally during replication or due to external chemical or physical causes. In sexual reproduction, the offspring gets nearly half of its DNA from each parent. Consequently, the offspring does not have DNA identical to one parent. It mixes up DNA in the species. However, mutations generate new genes, driving evolution. Sexual reproduction and mutation acting in concert introduced the diversity of life on earth we see today.

Once science becomes explanatory and predictive, it opens the way for innovations. Theories of mechanics and electromagnetism formulated in the late 19^th and early 20^th centuries brought forth modern engineering, transforming it from an empirical craft to a scientific technological discipline. Before the discovery of DNA structure and its function, biological innovations were largely empirical. Today we have genetic engineering – genes in organisms can be manipulated. The goal of more advanced genetic engineering, referred to as synthetic biology, aims to induce major genetic changes to organisms by incorporating several genes to alter biochemical, physiological and anatomical functions. Gene technology is rapidly transforming medicine, agriculture and biotechnology. Cures have been found for diseases formerly branded incurable.

How did DNA come into existence

Life is believed to have originated in prebiotic oceans enriched with carbon and nitrogenous substances. How did DNA originate there? Today, chemists can synthesize DNA in minutes, via selective procedures, only humans can do with their knowledge. Even in a vast ocean containing trillions of times more molecular ingredients than in a test tube, a molecule as complex as DNA is most unlikely to be created by random events during the largest possible time scales of the universe. A plausible scenario would be DNA evolving from simpler self-replicating molecules such as RNA (a single strand of DNA) precursors. Unlike RNA, DNA is highly stable and good stability is necessary for the evolution of advanced forms of life.

Epigenetics

Earlier we pointed out there are two golden sayings in our culture: “Arae gathi nare” and “Jammeta wada lokuei purudha (“Hereditary characters persist” and “Habits overtake heredity “). The first is a consequence of our genetic predisposition determined by DNA and explicit genes. However, the character of an individual is also influenced by the physical, social and cultural environment. Although completely non-genetic, our children frequently follow habits we indulge in. Again, the behavior of an individual is also influenced by the physical, social and cultural environment.

The environmental factors also trigger or silence genes. The study of this important genetic effect, which does not alter the sequence of base pairs, is referred to as epigenetics. Epigenetic effects could be deleterious or beneficial. Sometimes, chronic stress causes disease, including cancer. Research suggests engagement in creative and imaginative activities, and establishes favorable epigenetic changes in the brain. Inheritance is dictated mainly by the arrangement of base pairs in DNA. Epigenetic changes involve chemical changes in DNA without altering the sequence. These alterations are erasable but allow transmission to subsequent generations.

Conclusion: World DNA day message to lawmakers

The discovery of the structure of DNA stands as one of the most significant scientific discoveries in human history. It is a lesson to all those involved in research and education, telling how great discoveries originated. It is intense curiosity, imagination and preparation rather than mere indulgence in technologies that clear the path for discovery and innovation. A society that advocates policies conducive to discoveries, also develops new technologies that follow. If we just borrow technologies from places where they originated, hoping for quick economic returns, the effort would be a gross failure. Students, determined to be the best judging from exam performance, engage in professional disciplines and perform exceptionally. Why are we short of discoveries and innovations in those disciplines? Will our lawmakers ever realize the issue? They need to wonder why we are weak in science and poor in innovation. Right policies can even reverse adverse epigenetic attributes propagating in a society!

By Prof. Kirthi Tennakone
ktenna@yahoo.co.uk
National Institute of Fundamental Studies

REVIEWED BY Prof. Rajiva Wijesinha

Earlier this year, I sent her most recent book by an old friend, Kamala Wijeratne. Death of the Sperm Whale is her first book of poetry in four years, though in between she has published fiction, two books though both of them too were slim volumes. I am full of admiration for her in that she keeps going, the last of the poets whom I helped to a wider readership in the eighties, when I championed Sri Lankan writing in English, something hardly any academic was prepared to do in those conservative days.

Kamala Wijeratne

Kamala’s subjects are those she has explored in the past, but the use of the plural indicates that her range is expansive. She dwells much on nature, but she deals also with political issues, and engages in social criticism. There are several poems about Gaza, the multiple horrors occurring there having clearly affected her deeply. She repeatedly draws attention to the slaughter of children, the infants sent by God only to be taken back. And she deals with the destruction of the life of a doctor, after his healing, a theme that has kept recurring in the ghastly world which is subject to the whims of the incredibly nasty Netanyahu.

The title poem is about a whale destroyed by ingesting plastic, a tragedy to which we all contribute, though those who ‘loll on the beach, their senses dulled by the burgers they eat’ could not care less. More immediate is the simple account of a friend whose infant had died in hospital, when they diagnosed pneumonia too late.

Contrasting with these urgent statements are Kamala’s gentle perceptions, as when she writes of her son supporting her as she walks, while she thinks back to the days she supported him; of a marigold growing in a crack in a shrine, offering obeisance with its golden flowers to the Noble One; of birds investigating her dining room and deciding not to build there, the male lingering ‘confused and irritated’ but eventually following the female through the window for ‘She was mistress after all.’

She is deeply interested in the passing of time, and its impact on our perceptions. The first poem in the book is called ‘First Poem of 2024’ when she ‘heard the weeping of the dying year’, and went on to meditate on how we have categorised the passing of time, while the universe moves on regardless.

She welcomes the return of the Avichchiya, the Indian Pitta, a bird that has figured previously in her poetry, after six months, but this time she spares a thought for his case against the peacock, which stole his plumes.

There are two personal poems, one about a former student who turned her back on her when she had achieved success, the other about being nominated for a literary award, but not getting it after the excitement of attending the Awards Ceremony. Swallowing her disappointment, she congratulates the winner, noting that she will not go into ecstasies the next time she is nominated.

Paraphrase cannot do justice to Kamala Wijeratne’s gentle touch, which has expanded its reach over the years. So,A I will end by quoting from her tribute to Punyakante Wijenaike, another of the distinguished ladies whose work I promoted, the one before the last to leave us. The tribute ends, recalling her most impressive work Giraya,

Like the nutcracker
That makes a clean cut
You cut the human psyche
To reveal its darkest depths

by Kamala Wijeratne

On the occasion of World Earth Day, the conversation around sustainability often turns to forests, oceans, and climate. Yet, one of the most critical resources sustaining life remains largely unnoticed – soil. Beneath every thriving crop and every secure food system lies a complex, living ecosystem that quietly performs functions essential not just for agriculture, but for the health of the planet itself.

Soil is far more than a passive medium for plant growth. It is a dynamic and living system, teeming with microorganisms that drive nutrient cycling, regulate water movement, and support biodiversity at multiple levels. It acts as a natural reservoir, storing carbon and playing a crucial role in mitigating the impacts of climate change. The productivity, resilience, and long-term viability of agriculture are intrinsically tied to the health of this foundational resource.

However, decades of intensive agricultural practices have begun to take a visible toll. The increasing pressure to maximize yields has often led to excessive and imbalanced use of fertilisers, particularly nitrogen-heavy inputs. While these may provide short-term gains, their prolonged and unchecked use has resulted in significant nutrient imbalances within the soil. Essential micronutrients are depleted, soil organic carbon levels decline, and the rich microbial life that sustains soil fertility begins to diminish. The result is a gradual but steady erosion of soil health – one that ultimately reflects in reduced productivity and increased vulnerability of crops to stress.

Parallel to the challenge of soil degradation is the growing concern of water scarcity. Agriculture remains the largest consumer of freshwater resources, and inefficient irrigation practices continue to strain already depleting groundwater reserves. In an era marked by climate variability, erratic rainfall patterns, and increasing frequency of droughts, the need for efficient water management has never been more urgent.

Adopting scientifically sound and resource-efficient practices offers a clear pathway forward. Techniques such as rainwater harvesting and precision irrigation systems – like drip and sprinkler methods – enable farmers to optimize water use without compromising crop health. Complementary practices such as mulching and proper field levelling further enhance moisture retention and reduce water loss, ensuring that every drop contributes effectively to plant growth.

Equally important is the shift towards a more balanced and holistic approach to nutrient management. Soil testing must form the backbone of fertiliser application strategies, ensuring that crops receive nutrients in the right proportion and at the right time. Integrating organic sources – such as farmyard manure, compost, and green manure – helps replenish soil organic matter, improving both soil structure and its capacity to retain water and nutrients.

Sustainable soil management also extends to cultivation practices. Reduced or minimum tillage helps preserve soil structure, while crop rotation and intercropping promote biodiversity and break pest and disease cycles. The inclusion of cover crops protects the soil surface from erosion and contributes to organic matter buildup, reinforcing the soil’s natural resilience.

In recent years, there has also been growing recognition of the role played by biological and enzymatic inputs in enhancing soil health. These inputs stimulate beneficial microbial activity, improve nutrient availability, and increase nutrient use efficiency. By reducing dependence on excessive chemical fertilisers, they offer a pathway toward more sustainable and environmentally responsible farming systems. The transition to sustainable agriculture is not merely a technical shift – it is a collective responsibility.

Farmers, scientists, industry stakeholders, and policymakers must work in tandem to promote awareness and facilitate the adoption of practices that conserve soil and water resources. The long-term sustainability of agriculture depends on decisions made today, at both the field and policy level. As we mark World Earth Day, the message is clear: the future of agriculture is inseparable from the health of our soil and the stewardship of our water resources. A fertile, living soil is not just the foundation of productive farming – it is the cornerstone of ecological balance and food security. Protecting it is not an option; it is an obligation we owe to generations to come. (The Statesman)

(The writer is Chairman Emeritus, Dhanuka Agritech.)