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Showing posts with label Biology. Show all posts
Showing posts with label Biology. Show all posts

Monday, March 04, 2024

Why did Humans lose their Tails?

 A new study published on February 28th, 2024 in the journal Nature has identified the specific genetic mutation responsible for ancestral humans and apes losing their tails around 25 million years ago.

The Tailless Ancestor Mystery

While monkeys possess tails, an ancestor species that humans share with apes underwent a key genetic divergence resulting in tail loss over the course of evolution. However, the actual genetic drivers behind this dramatic physiological change were unknown until now.

Serendipitous Discovery

The study’s lead author Bo Xia, currently with the Broad Institute, got intrigued by the evolutionary puzzle after injuring his own tailbone. Along with teams from New York University (NYU) Langone Health and Applied Bioinformatics Labs, his curiosity-driven investigation pinpointed unique jumping gene activity that deactivated the tail-growth gene TBXT.

The Role of Jumping Genes

Over generations, DNA accumulates changes enabling species adaptation through evolution. The study found older repetitive genetic sequences called Alu elements that jumped into strategic introns of the TBXT gene.

Introns are non-coding DNA portions that get sliced out before the gene sequence is converted into proteins. The intron-inserting DNA ‘jumping genes’ disrupted normal protein formation by the tail-regulating TBXT gene.

This genetic mutation was spotted in apes but not monkeys, coinciding with ancestral tail disappearance in the former group after both diverged from a common monkey group ancestor.

Alternative Splicing and Multiple Proteins

The Alu element insertion caused the TBXT gene to undergo alternative splicing and generate multiple proteins variants instead of one form coded by monkeys. This indicates more complex downstream impacts compared to straightforward gene disabling.

Researchers confirmed through lab experiments that inserting the exact Alu sequences into mice TBXT gene also led to truncated tails in mice besides increasing risk of spinal defects.

Evolutionary Significance

The study illustrates how small non-coding DNA changes can profoundly reshape physiology over thousands of generations to enable evolutionary adaptation.

Loss of stabilizing tails may have enabled ancestral apes to adopt bipedal motion crucial for later human development. The mutation likely occurred randomly without an initial adaptive benefit.

However, it conferred survival value once interplay between taillessness and walking upright offered mobility advantages within forest habitats.

Future Impact

Beyond solving the longstanding tail evolutionary mystery, the pathbreaking discovery promises to accelerate genetics research on non-coding DNA and complex alternative gene splicing effects.

Intron sequences dismissed previously as ‘junk DNA’ now open up new appraisal of their hidden role in driving evolutionary changes to anatomy over time.

Deeper analysis can reveal if similar jumping gene insertions underlie other evolutionary divergences between ancestral primates and humans.

Conclusion

The study underscores how small-scale genetic changes can catalyze sweeping physiological adaptations central to a species’ evolutionary history. Shedding light on humanity’s tailless past sets the stage for fresh investigation into other attribute transformations during ancestral primate evolution over millions of years until modern humans emerged.

Wednesday, April 19, 2023

Plant ‘cries’: Recalling Jagadish Chandra Bose

 

Researchers have picked up ‘distress’ calls from plants in difficulty, such as when they need water. More than a century ago, a pioneering Indian scientist had demonstrated that plants can ‘feel’ pleasure and pain.


Late last month, a group of researchers from Tel Aviv University in Israel reported that they had been able to pick up distress noises made by plants. The researchers said these plants had been making very distinct, high-pitched sounds in the ultrasonic range when faced with some kind of stress, like when they were in need of water.

This was the first time that plants had been caught making any kind of noise, and the breakthrough research findings made global headlines. But many Indians just had a sense of déjà vu. Several previous generations of Indians had grown up hearing that Jagadish Chandra Bose had shown, more than a century ago, that plants experienced sensations and were able to feel pleasure and pain just like animals. Children were often advised not to pluck leaves, flowers or twigs because that could cause pain to the plants or trees. The discovery that plants ‘cry’ in distress, therefore, did not come as much of a surprise to them. It seemed just a logical extension of J C Bose’s work. Bose might not be a very familiar name to the current generation, but he is a colossal figure of Indian science. A physicist-turned-biologist, Bose, who lived between 1858 and 1937, made pioneering contributions in both the fields and was the first Indian to have made a powerful impact on modern science, much before Srinivasa Ramanujan, C V Raman, or Satyendra Nath Bose, a student of Jagadish, arrived on the scene.

J C Bose could — many believe he deservedly should — very well have been India’s first Nobel Prize winner, ahead of his life-long friend and confidant Rabindranath Tagore, with whom he used to have a prolific, and often poetic, correspondence.

Bose’s science

Jagadish Chandra Bose is remembered for two things — his work on wireless transmission of signals, and on the physiology of plants. He is also credited as one of the first contributors to solid state physics. Sir Neville Mott, Nobel Prize winner in 1977, is said to have remarked that Bose was “at least 60 years ahead of his time and he had anticipated the p-type and n-type semiconductors”, according to an account in Remembering J C Bose, a 2009 publication by D P Sen Gupta, M H Engineer and V A Shepherd.

Bose is widely believed to be the first one to generate electromagnetic signals in the microwave range. In 1895, just a year after he began his active research, he demonstrated, before an audience in Kolkata, how microwaves could be used, wirelessly, to ring an electric bell on the other side of a building. He published as many as 12 papers on radio waves in the Proceedings of the Royal Society, and many more in some other prestigious journals, as reported in the book Jagadis Chandra Bose and the Indian Response to Western Science, by Subrata Dasgupta. He lectured on his work at some highly publicised scientific gatherings in Europe, in the presence of some of the leading scientists of the day. He was the first one to come up with radio receivers, which enabled wireless telegraphy.

And yet, Guglielmo Marconi, an Italian scientist who carried out the first transmission of signals across the Atlantic in 1901, is recognised as the sole inventor of the radio. Marconi, along with another colleague, was awarded the 1909 Nobel Prize for work that Bose is known to have accomplished earlier.

It was not just bias, but as several accounts put it, a reluctance on Bose’s part to obtain patents for his work, that deprived him of the Nobel. As mentioned in the publication Remembering J C Bose, he wrote to Tagore about being approached by a big businessman in Europe with the offer to get his work patented. Bose not just rejected the offer, he felt disgusted at the idea of making money from science. “If only Tagore would witness the country’s (England’s) greed for money,” Bose wrote to Tagore. “What a dreadful, all-consuming disease it was”.

His study of plants

Bose, rather abruptly, changed tack in the initial years of the 20th century and began to focus his attention on plants. But as Professor A S Raghavendra from the University of Hyderabad explained, Bose’s work was not as disjoined as it seems.

“J C Bose was extremely talented at picking electric signals. The other thing he was extremely creative at was making instruments. Bose was working with rudimentary facilities and, yet, was able to build some remarkably sensitive instruments. He used these instruments to try and detect the faintest signals from the plants. He was carrying over his skills from physics to probe the world of biology,” Raghavendra, a former J C Bose National Fellow, who has written extensively on Bose’s work, told The Indian Express.

“His (Bose’s) contributions to the communication systems in biology as well as physics are amazing. He devoted strong attention to studies on the biology of movements, feelings and nervous system. The word ‘feelings’ was used for plants, but clearly this is a matter of semantics; plants react both chemically and physically to touch, but to use the word ‘feeling’ or ‘sensation’ as we know it is quite different. The simple experiments of Bose revealed a high degree of similarity in the responses of plant and animal tissues to external stimuli. This principle was amply demonstrated later by biophysicists, using highly sophisticated instruments,” Raghavendra wrote in a 2010 paper.

In a way, Bose was possibly the world’s first biophysicist. But some of his work became controversial as well, particularly when he claimed that not just plants, even inanimate inorganic matter could respond to stimulus, and that there was actually no sharp demarcation between living and non-living worlds. Such “mental leaps” have sometimes been attributed to Bose’s “deep convictions in Indian philosophy” and his “faith in universalism”. Bose regarded plants to be the “intermediates in a continuum that extended between animals and the non-living materials”, according to the authors of Remembering J C Bose.

His work on plants, too, was also not easily digested. Bose himself records the opposition he faced. In a letter to Tagore, he mentioned a lecture he was delivering in Europe. “When I commented during my lecture at the Royal Society that plants which come between the living and the non-living will provide similar response, (John) Burden Sanderson (a leading physiologist of his time) told me that he had worked all his life with plants. Only mimosa (touch-me-not) responds to touch. That ordinary plants should give electrical response is simply impossible. It cannot be”. Over the years, much of Bose’s work has been confirmed, though his genius is not always acknowledged. “He was much ahead of his times, no doubt. Many of his contemporaries did not fully understand him,” Raghavendra said, adding that the recent discovery of distress noise from plants could lead to some exciting research in the field. “We cannot lose sight of the fact that it was Bose who started it all”.

Written by Amitabh Sinha 


Source: The Indian Express, 19/04/23


Wednesday, February 20, 2019

What is 'Turkheimer’s laws' in Biology?


This refers to a set of laws regarding the heritability of various behavioural traits and the relative influence of genes and environment on human behaviour. The first Turkheimer law states that all human behavioural traits are heritable. The second law states that the influence of genes on human behaviour is greater than the family environment. The final law argues that a significant number of behavioural traits may be explained neither by genes nor the family environment. Turkheimer’s laws were proposed by American psychologist Eric Turkheimer in his 2000 paper “Three Laws of Behavior Genetics and What They Mean”.

Source: The Hindu, 20/02/2019

Friday, February 01, 2019

What is primitive reflex in biology?


This refers to reflex actions exhibited by newborn babies that involve no conscious thought. These reflex actions usually subside as the frontal lobe of the brain of the infant develops sufficiently during the first few months of its life. In some cases, however, certain primitive reflexes may persist beyond the first year of a child’s life. The sucking reflex, stepping reflex, and the rooting reflex are some of the primitive reflexes exhibited by newborn babies. It is believed that some primitive reflexes may simply be remnants of behaviour from the evolutionary past which may have helped infants to survive in tough conditions.

Source: The Hindu, 1/02/2019

Wednesday, January 09, 2019

In Biology, what is Extreme Male Brain?


Also known as the empathising-systemising theory, this refers to a theory of autism which states that the condition may be the result of overexposure of foetuses to testosterone from their mothers. Such overexposure to testosterone may cause the brains of people with autism to specifically adapt to analyse and construct systems while severely lacking in the ability to empathise with fellow human beings. The extreme male brain theory was proposed by British clinical psychologist Simon Baron-Cohen. It derives its name from the fact that the male brain is typically suited for systemising purposes while the female brain is built for empathising.

Source: The Hindu, 9/01/2019

Tuesday, December 18, 2018

What is 'selfish brain theory' in Biology?


This refers to a scientific hypothesis which states that the brain prioritises its own relatively high energy needs over those of the rest of the body. This hypothesis overturned the earlier belief among scientists that the energy needs of various organs of the body are met equally without any kind of internal discrimination within the body. The selfish brain theory was developed by German brain researcher Achim Peters to explain the prevalence of obesity as the result of an imbalance in the energy supplied to the brain and the metabolic system. Some believe that the selfish brain may be the consequence of evolutionary forces favouring an alert brain over an agile body.

Source: The Hindu, 18/12/2018