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Rajini Rao
Life is an experiment. Experiments are my life.
Life is an experiment. Experiments are my life.

Rajini's posts

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Olympic Gold..or....Green?

♒ We know that green is Brazil's favorite color, and the Olympics are trying to Go Green for the environment, but even so, the overnight change in color of the Olympic swimming pool from an azure blue to murky green took scientists and sportsmen by surprise. While officials hastened to assure athletes that the green waters posed no health threat, the mystery caused much speculation. Caipirinha-flavored Soylent? Stiffed by Trump’s pool cleaning service? Who peed in the water?

♒ “Midafternoon, there was a sudden decrease in the alkalinity in the diving pool, and that’s the main reason the color changed,” said Mario Andrada, a Rio 2016 spokesman. So, the pool became more acidic. But acidic water is not green. There are two likely explanations: first, excess copper in the water can turn it green, but not murky. The latter is caused by a sudden and rapid growth of algae, triggered by the warm weather, lack of wind, insufficient chlorine and ineffective filters.

♒ Algal spores can enter the water inadvertently, carried by wind, rain and contaminated swimsuits. When the conditions are right, they can "bloom" overnight. Because these algae are visible only under the microscope, there must be millions of them in the water to change the pool color from blue to green. One way to deal with them, after normalizing the pH, is *superchlorination*—aka shocking them with high levels of chlorine. Not all the Olympians are complaining: Canadian divers said that the contrast with the sky helped them win the bronze.

♒ Pix: The Olympic diving pool on August 8 (left) and the Olympic diving pool on August 9 (right) Image: AP

#rioolympics2016   #swimming  

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Eye See You: Moving Retina in Jumping Spiders

⦿ Jumping spiders (Salticidae) don't use a web to catch prey. Instead they locate, stalk and mount a jumping ambush when they are 1-2 cm away. To do this, they need to detect and then evaluate objects so they don't confuse a potential mate as prey! Fortunately, jumping spiders have among the sharpest vision among invertebrates.

⦿ Unlike insects, spiders don't have compound eyes. Instead their 8 "simple" eyes point forward (for high focus) and sideways (to detect motion). Strategically, this is similar to the division of labor in our eyes: we detect peripheral vision at the edges of our retina with low resolution but wide field of view, and sharp images at the fovea in the center of the retina, which is packed with a high density of vision receptors, but has a limited field of view. Since the spider's large central eyes are set close together and have a limited field of view, they must be moved to point the fovea towards the object. How do they do this?

⦿ Involuntary leg movements are triggered by stimuli from the lateral eyes to reposition the body. However, the spider cannot swivel its whole eyeball as we do, because the lens is built into the carapace, or outer skeleton. Instead, a set of six muscles moves the retina: up and down, sideways and rotationally, while the lens stays fixed. In a transparent spider, you can see the unusual movements of the retina in the tube-like principle eyes. Just one more addition to the cuteness quotient of these tiny spiders! 

REF: M.F. Land (1969) Movements of the retinae of jumping spiders (Salticidae: Dendryphantinae) in response to visual stimuli.

Video Source: Yellow amycine jumping spider from Ecuador,

GIF Source:
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Red, White and Grape: From Jumping Genes to Wrapping Leaves

Red or White? Even King Tutankhamun (1332-1322 B.C.) prudently stashed away amphorae of both red and white wines to enjoy in the afterlife. Biochemically, a single class of pigments found in grape skin, the anthocyanins, separates the red from white. White grapes arose from their wild, dark berried ancestors by not one, but two rare and independent genetic events: either one alone would not have given us the white grape. In fact, all ~3000 white cultivars today carry these same gene disruptions, pointing back to a common ancestor that arose millennia ago. The disrupted genes code for transcription factors, aka master regulators of biochemical pathways that can turn other genes on or off.

Science sleuths have peeked back into the gene history of Vitis vinifera to figure this out.

First, the MybA gene duplicated, giving two side-by-side copies, both active in making anthocyanins and red berries. Somewhere along the way, one of them, the MybA2 gene accumulated two mutations (depicted as stars) that rendered the resulting protein non-functional.

Independently, a “jumping gene” or retrotransposon, (green triangle) landed within the adjacent backup gene MybA1, knocking it out as well. The resulting plant, termed heterozygous, still bore red berries, because the unmutated genes on the other chromosome were active. Eventually, two heterozygous plants bred together and some offspring received both chromosomes with two nonfunctional MybA genes.

Voila, white grapes!

If you’ve ever snacked on delicious dolmas, then you know that the goodness of the grape vine goes beyond berries. Legend has it that the gods of Mount Olympus feasted on the tender leaves of the grape wrapped around morsels of rice or meat, alongside ambrosia and nectar! Although stuffed grape leaves are common around the Mediterranean, Greeks claim that dolmades were co-opted by the army of Alexander the Great to parcel out limited rations of meat during the seige of Thebes.  Luckily, you only need to lay seige on your local Middle Eastern grocery store to find jarred leaves, preserved in brine. Unfurl them gently and give them a good wash to get started. It doesn’t hurt to have a glass of your favorite vintage, red or white, on hand before embarking on this project!

For the recipe on stuffed rice dolmas, visit my blog at:

REF:White grapes arose through the mutation of two similar and adjacent regulatory genes. Walker et al., 2007
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Owl Be Seeing You

It's time for the #SuperbOwl and #ScienceSunday

Did you know that the eyes of an owl are 5% of its body weight? Imagine Peyton Manning with eyes the size of a baseball.. Their large pupils dilate at night, harvesting more light to be captured by an abundance of rods, specialized for night vision. Their eyes don't have as many cone cells as we do, so their color vision is not that great. But they can see up to 100 times better than the Broncos at night! 

How does the owl rotate its head without wringing its neck? An owl has twice as many vertebrae compared to the 7 in humans, giving it a 270 degree flexibility, without tearing the delicate blood vessels in their necks and heads, and cutting off blood supply to their brains.. That's because unlike human vertebrae, the vertebrae of the owl have large cavities, about ten times the diameter of the vertebral artery that goes through, allowing for plenty of slack. The artery also enters the cervical vertebrae at a higher point, for more freedom of movement. It is heavily networked so that blood supply to the brain and eyes is not interrupted by twisting of the neck even if one route is blocked. Astonishingly, the blood vessels at the neck became wider as they branched, in contrast to that of mere humans, where they get smaller and narrower. 

Read More: Research by +Michael Habib  and colleagues at Johns Hopkins University on the mystery of the Owl's neck. This award winning study was featured in Science magazine and may be the first use of angiography, CT scans and medical illustrations to unravel the mystery of the magnificent owl. 

For +rare avis  who wanted to know about the #SuperbOwl :)
Image Source: Northern Hawk Owls
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Why are there "dew drops" at the tips of leaf veins?

❦ Have you ever seen clear orbs of water glisten along a leaf edge? You may have mistaken them for dew drops, which are caused by moisture from the air condensing on cool surfaces. But these drops are only found at the edges of leaves and if you look around- they won't be found on dead leaves. So what are they?

❦ Plants use a plumbing system of xylem tubes to move water and nutrients. During the day, transpiration (water evaporation) from leaves creates a vacuum that pulls the column of water up from the roots to the leaves. At night, the stomata (leaf pores) close, transpiration stops and salts accumulate in the xylem of roots, drawing in water from the surrounding soil by osmosis. The excess water rises up the xylem tubes and is forced out at the leaf tips through openings called hydathodes. This exudation of plant sap is known rather inelegantly as guttation, and only happens at night. The water pressure is not strong enough to rise beyond 3 feet, so guttation is not seen on tree leaves. The thermal image (inset) taken by infrared photography shows the cooler temperature (blue) in the guttation droplets.

❦ When the drops dry, they sometimes leave behind a residue of salts and minerals. This is not a problem, unless the soil is over-fertilized resulting in fertilizer burn of leaf tips. In the same way, guttation droplets in corn seedlings were shown to have high levels of neonicotinoid compounds, used as pesticidal coatings on the seed. These concentrations could be a lethal dose for honey bees that sip on guttation drops as a water source. While shedding toxins through guttation drops protects the plant, it may have repercussions - both beneficial and harmful, on insects and other animals. 

Inset of thermal image:

REF on neonicotinoids in guttation droplets #openaccess:

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The Flight of the Hummingbird

A route of evanescence
With a revolving wheel
A resonance of emerald,
A rush of cochineal

With these words, the poet Emily Dickinson summed up the fleeting magic of the hummingbird.  

Hummingbirds are the only vertebrates capable of hovering in place. In addition to flying forwards, they can also fly backward and upside down! They are tiny: the smallest bee hummingbird of Cuba weighs less than 2 grams, less than a penny! Add to this their speed- they can clock up to 45 mph, and stamina- they can fly 18 straight hours, and you may appreciate their unusual metabolism. In fact, they have the highest metabolic rate of any warm blooded animal. 

With a heart beat of 1,200/min and wing beat of 200/sec during flight, hummingbirds generate a tremendous amount of heat. Because their muscles are only ~10% efficient, much of the energy they consume is released as heat. But their thick plumage of feathers keeps in the heat: useful when the bird wants to conserve body heat, but a problem during flight. 

Using infrared thermal photography, scientists have found that hummingbirds (and probably most birds) lose body heat from three areas seen as bright white spots in the gif below: the region around the eyes, at the shoulder where the wings meet the body, and the feet, which they can dangle downward to dissipate even more heat. 

Animated Photo

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Gene Drives: Green Signal or Back Seat? 

What is the deadliest animal on earth? If you're thinking of the great white shark or a venomous snake, you could be wrong. Counting human deaths, it is the innocently named (Spanish for "little fly") mosquito. Millions, mostly children in third world countries, are killed or sickened each year by malaria, dengue, yellow fever and encephalitis caused by parasites and viruses that are transmitted by mosquito bites. This happens despite billions of dollars spent, years of research and potential cures ranging from vaccines and drugs to public health management. 

Stop or Go, that is the Question: Imagine if the mosquito could kill the parasite before it has the chance to spread to its human victims. For example, the mosquito could be engineered to make antibodies against Plasmodium, killing the parasite soon after it enters the mosquito after a blood meal. Just like a vaccination, nearly all mosquitoes would need to carry this new trait to be effective. There is a way to do this and it is not a new idea. What used to be theory, however, has just become a reality. A new paper published in the journal PNAS has now changed the question from Can we do this? to Should we do this?

What are Gene Drives?: Normally, the chance that any gene trait is passed from parent to offspring is 50%, since only one of a chromosome pair is inherited from that parent. But some selfish genes can copy themselves so that both chromosomes carry the trait, which now affects 100% offspring. A gene drive consists of DNA sequences that provides the technical ability to do this. With the new CRISPR/Cas9 tool that precisely cuts and inserts any gene of interest, the gene drive has become a reality. 

Can Gene Drives work on Humans? Gene drives work best in fast reproducing species, like mosquitoes, that can be released in large numbers. For this reason, they are not going to be effective in spreading inadvertently through humans, or even commercial crops and animals which are bred by controlled processes like artificial pollination and insemination.  

Gene Drives are Natural: For example, a gene called P element swept through all fruit flies in the wild, but is not found in lab strains that were isolated before it spread. 

Gene Drives can be Reversed: For each gene drive that spreads a trait, a reverse gene drive can undo the genetic changes in the original strain. Such reversal drives should be tested in advance, and could be released to stop the spread of any unintended consequences.

What else can Gene Drives do? Besides targeting mosquitoes, gene drives could be used to eradicate invasive species, or reverse resistance to herbicides and pesticides. 

Take the Poll: A public conversation based on sound scientific information, weighing pros and cons, must be the starting point for developing policy. Engineered mosquitoes that could rapidly spread in the wild and eradicate the malarial parasite have been made. Here is the question: Should we use Gene Drive engineered mosquitoes to fight Malaria? 

FAQ on Gene Drives:
Image: Matt Panuska
Pop Science Read:
Advanced Read:
963 votes
votes visible to Public
Poll option image
Yes, release the engineered mozzies!
No, there may be unintended consequences

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I am really worried about priorities..

❖ On a recent science post about the evolution of land plants, a community member worried: "what about poverty?? people are dying in hunger, lack of medical support, clean water and other simple things which can be fixed... but without fixing something for them we are trying to find water in Mars. I'm really worried about the priorities.."

❖ A similar comment lamented the cost of curiosity in the search for earth-like planets ( Physics professor Robert McNees had an awesome response:

❝ You posted your comment using technology that exists only because of a chain of discoveries and insights that began with fascination-driven research in the late 19th century.❞

❝ If Balmer hadn't studied spectral lines, Planck may not have proposed the quantum. Then Bohr may not have conceived his model of the atom, which means Heisenberg and Schrödinger wouldn't have developed their formulations of quantum mechanics. That would have left Bloch without the tools he needed to understand the nature of conduction in metals, and then how would Schottky have figured out semiconductors? It's hard to imagine, then, how Bardeen, Brattain, and Schockley would have developed transistors. And without transistors, Noyce and Kilbey couldn't have produced integrated circuits.❞

❝ Almost every major technological advance of the 20th and 21st centuries originated with basic research that presented no obvious or immediate economic benefit. That means no profit motive, and hence no reason for the private sector to adequately fund it. Basic research isn't a waste of tax dollars; it's a more reliable long-term investment than anything else in the Federal government's portfolio.❞

GIF: Johns Hopkins professor Andy Feinberg spent several days on NASA's zero gravity aircraft (known as "vomit comet") trying out different pipetting techniques for future experiments in space. It wasn't that easy with flying pipet tips and tubes! Andy did eventually figure out the best technique (using positive displacement pipets, seen in the second video in this link Feinberg is leading one of ten experiments in NASA's Twin Study to examine epigenetics and other biological changes that affect astronauts in space. Samples from Scott Kelly, who is spending a year onboard the ISS, will be compared with those from his twin on earth, Mark. Feinberg credits NASA for funding this study. He says, “They're very curious people. They really want to know.”

Who knows, one day we may even grow potatoes on Mars! :)

Share your favorite example of the unexpected benefits of basic research! 

Shout out to +Gnotic Pasta  who made the GIF. Thanks, Dan! 
Animated Photo

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Science Mystery Pix

Stomatal pores under a leaf? Sand dunes on Mars? Clams clamoring to be fed? Hint: the image illustrates an evolutionary adaptation. Take a guess, then read on!

Secret of Serotiny: In 1961, a fire destroyed 28,000 acres of forest in Montana. Since then, the lodgepole pine has established dominance over this vast acreage, with a density of tens of thousands of trees per acre. Yet, this pine normally does not spread its seed beyond a range of some 200 meters. How did the lodgepole pine achieve this remarkable biotic potential?

Its secret was serotiny: millions of seeds per acre were stored inside cones, high up at the canopy top of mature stands, for just this scenario. The heat of the fire melted the resin that kept the cones closed, releasing seeds to be carried by wind or gravity over several days, to land on burned but cooling ground. With little competition, more light, warmth and nutrients from ash, the seedlings flourished, making this pine an aggressive pioneer species.  

Serotiny is the adaptation by some plants that hold on to their seeds for decades after they are mature, releasing them only in response to a specific environmental trigger. The trigger could be dryness, water, or fire. Some desert plants have adapted to release seeds after rainfall, when the chances of successful germination are high. Other plants release seeds only after they die, a feature known as necriscence. Oddly, fire-survival strategies may be paired with fire-embracing adaptations, such as retaining dead (and flammable) branches instead of the more common practice of self pruning . Known as niche construction, this double strategy ensures removal of poorly adapted plants in regions susceptible to natural fires. 

The Fiery Cretaceous: Fire has been an effective agent of natural selection for at least 125 million years and possibly longer! The high oxygen levels (23-29% compared to today's 21%) in Earth's paleoatmosphere of the early Cretaceous fueled frequent fires, captured as charcoal in the fossil records. Since then, fire adapting traits in plants arose independently, many times.  Our Mystery Pix can now be revealed as the cone of a Banksia tree, endemic to Australia, with open seed pods after a bushfire. Photo via PinkRockAus's Fotothing

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Project 523: From Chinese Secrets to Nobel Gold 

☯ On May 23, 1967 a secret military project was launched by the Chinese government. It was the height of the Vietnam war, and the communist north was losing more soldiers to the scourge of malaria than to the battlefield. An emergency plea was made to a powerful sympathizer, Chairman Mao Zedong, to find a cure. Code named Project 523 (after the date), more than 500 scientists were recruited from 60 military and civilian organizations, remarkably at the height of China's Cultural Revolution which closed universities and banished scientists and intellectuals. One group of scientists was tasked with searching through ancient Chinese records of herbal remedies.

☯ 39 year old phytochemist, Youyou Tu, was sent to the sweltering rain forests of Hainan, an island in southern China, where she witnessed the devastation of malaria first hand. By then, many ancient herbal compounds had been tested. The extract of quinghao (green-blue wormwood) appeared to be effective, but success was sporadic. Tu carefully read the recipe of 4th century writing of Ge Hong: qinghao, one bunch, take two sheng [2 × 0.2 l] of water for soaking it, wring it out, take the juice, ingest it in its entirety. Tu reasoned that extraction by boiling might destroy the active ingredient. So she tested a cold ether extract of the plant and it worked. She even voluntarily consumed the extract to make sure it was safe, then tested it on human patients. Her results were published anonymously in 1977. Today, 84 year old Youyou Tu received the Nobel Prize for Medicine, which she shared with two other scientists, an Irishman and Japanese, who worked on treatment of other parasitic diseases. 

☯ The success of artemisinin as a modern day miracle cure for Plasmodium falciparum malaria (spread by mosquitoes, and blamed annually for 1 million deaths world wide), rests on the breakthroughs of hundreds of scientists. Those who discovered a richer source of the drug in Artemisia annua grown in Sichuan province, those who purified the drug away from toxic contaminants, who solved the new and unusual chemical structure, synthesized better and safer derivatives for the treatment of malaria. While celebrating her success as the first Chinese woman to receive a Nobel in Medicine, let us not forget that Youyou Tu's Nobel represents an entire field of research. Tu herself is a modest individual who has drifted into obscurity despite receiving a Lasker Award, the so-called American Nobel, in 2011. At the time, she said, "I think the honor not only belongs to me but also to all Chinese scientists."

Project 523:
Nobel Press Release:
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