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Earth Day is an annual celebration, championed by the Earth Day Network, which focuses on promoting environmental protection around the world. The Earth Day Network’s mission is to build a healthy, sustainable environment, address climate change, and protect the Earth for future generations. The theme for Earth Day 2016 is Trees for the Earth, raising awareness around protecting the Earth’s forests.
These are the images I carry in memory that form my understanding of passion and compassion in science: Rachel Carson waking at midnight to return to the sea the microscopic marine organisms she has been studying, when the tidal cycle is favorable to their survival; John Muir clinging to the upper branches of a tall pine during a violent storm, reveling in the power of natural forces.
The soils surrounding the village where I live in the north west of England have abundant fertility. They mostly formed in well-drained, clay-rich debris left behind by glaciers that retreated from the area some ten thousand years ago, and they now support lush, productive pasture, semi-natural grassland and woodland. Although the pastures are managed more intensively than they were in the past, most of them are well drained, and receive regular dressings of manure along with moderate fertiliser, and are regularly limed, which keeps the land productive and the soil in good health.
Another ‘Awareness Day’, International Kissing Day, is coming up on July 6. It might not seem obvious but kissing, like most subjects can now be easily linked to the science of DNA. Thus, there could be no more perfect opener for my Double Helix column, given the elegance and beauty of a kiss. To start, there is the obvious biological link between kissing and DNA: propagation of the species. Kissing is not only pleasurable but seems to be a solid way to assess the quality and suitability of a mate.
DNA is the foundation of life. It codes the instructions for the creation of all life on Earth. Scientists are now reading the autobiographies of organisms across the Tree of Life and writing new words, paragraphs, chapters, and even books as synthetic genomics gains steam. Quite astonishingly, the beautiful design and special properties of DNA makes it capable of many other amazing feats. Here are five man-made functions of DNA, all of which are contributing to the growing “industrial-DNA” phenomenon.
Galileo and some of his contemporaries left careful records of their telescopic observations of sunspots – dark patches on the surface of the sun, the largest of which can be larger than the whole earth. Then in 1844 a German apothecary reported the unexpected discovery that the number of sunspots seen on the sun waxes and wanes with a period of about 11 years.
Initially nobody considered sunspots as anything more than an odd curiosity. However, by the end of the nineteenth century, scientists started gathering more and more data that sunspots affect us in strange ways that seemed to defy all known laws of physics. In 1859 Richard Carrington, while watching a sunspot, accidentally saw a powerful explosion above it, which was followed a few hours later by a geomagnetic storm – a sudden change in the earth’s magnetic field. Such explosions – known as solar flares – occur more often around the peak of the sunspot cycle when there are many sunspots. One of the benign effects of a large flare is the beautiful aurora seen around the earth’s poles. However, flares can have other disastrous consequences. A large flare in 1989 caused a major electrical blackout in Quebec affecting six million people.
Interestingly, Carrington’s flare of 1859, the first flare observed by any human being, has remained the most powerful flare so far observed by anybody. It is estimated that this flare was three times as powerful as the 1989 flare that caused the Quebec blackout. The world was technologically a much less developed place in 1859. If a flare of the same strength as Carrington’s 1859 flare unleashes its full fury on the earth today, it will simply cause havoc – disrupting electrical networks, radio transmission, high-altitude air flights and satellites, various communication channels – with damages running into many billions of dollars.
There are two natural cycles – the day-night cycle and the cycle of seasons – around which many human activities are organized. As our society becomes technologically more advanced, the 11-year cycle of sunspots is emerging as the third most important cycle affecting our lives, although we have been aware of its existence for less than two centuries. We have more solar disturbances when this cycle is at its peak. For about a century after its discovery, the 11-year sunspot cycle was a complete mystery to scientists. Nobody had any clue as to why the sun has spots and why spots have this cycle of 11 years.
A first breakthrough came in 1908 when Hale found that sunspots are regions of strong magnetic field – about 5000 times stronger than the magnetic field around the earth’s magnetic poles. Incidentally, this was the first discovery of a magnetic field in an astronomical object and was eventually to revolutionize astronomy, with subsequent discoveries that nearly all astronomical objects have magnetic fields. Hale’s discovery also made it clear that the 11-year sunspot cycle is the sun’s magnetic cycle.
Sunspot 1-20-11, by Jason Major. CC BY-NC-SA 2.0 via Flickr.
Matter inside the sun exists in the plasma state – often called the fourth state of matter – in which electrons break out of atoms. Major developments in plasma physics within the last few decades at last enabled us to systematically address the questions of why sunspots exist and what causes their 11-year cycle. In 1955 Eugene Parker theoretically proposed a plasma process known as the dynamo process capable of generating magnetic fields within astronomical objects. Parker also came up with the first theoretical model of the 11-year cycle. It is only within the last 10 years or so that it has been possible to build sufficiently realistic and detailed theoretical dynamo models of the 11-year sunspot cycle.
Until about half a century ago, scientists believed that our solar system basically consisted of empty space around the sun through which planets were moving. The sun is surrounded by a million-degree hot corona – much hotter than the sun’s surface with a temperature of ‘only’ about 6000 K. Eugene Parker, in another of his seminal papers in 1958, showed that this corona will drive a wind of hot plasma from the sun – the solar wind – to blow through the entire solar system. Since the earth is immersed in this solar wind – and not surrounded by empty space as suspected earlier – the sun can affect the earth in complicated ways. Magnetic fields created by the dynamo process inside the sun can float up above the sun’s surface, producing beautiful magnetic arcades. By applying the basic principles of plasma physics, scientists have figured out that violent explosions can occur within these arcades, hurling huge chunks of plasma from the sun that can be carried to the earth by the solar wind.
The 11-year sunspot cycle is only approximately cyclic. Some cycles are stronger and some are weaker. Some are slightly longer than 11 years and some are shorter. During the seventeenth century, several sunspot cycles went missing and sunspots were not seen for about 70 years. There is evidence that Europe went through an unusually cold spell during this epoch. Was this a coincidence or did the missing sunspots have something to do with the cold climate? There is increasing evidence that sunspots affect the earth’s climate, though we do not yet understand how this happens.
Can we predict the strength of a sunspot cycle before its onset? The sunspot minimum around 2006–2009 was the first sunspot minimum when sufficiently sophisticated theoretical dynamo models of the sunspot cycle existed and whether these models could predict the upcoming cycle correctly became a challenge for these young theoretical models. We are now at the peak of the present sunspot cycle and its strength agrees remarkably with what my students and I predicted in 2007 from our dynamo model. This is the first such successful prediction from a theoretical model in the history of our subject. But is it merely a lucky accident that our prediction has been successful this time? If our methodology is used to predict more sunspot cycles in the future, will this success be repeated?
Headline image credit: A spectacular coronal mass ejection, by Steve Jurvetson. CC-BY-2.0 via Flickr.
They might be short-lived — but between the time a bubble is born (Fig 1 and Fig 2a) and pops (Fig 2d-f), the bubble can interact with surrounding particles and microorganisms. The consequence of this interaction not only influences the performance of bioreactors, but also can disseminate the particles, minerals, and microorganisms throughout the atmosphere. The interaction between microorganism and bubbles has been appreciated in our civilizations for millennia, most notably in fermentation. During some of these metabolic processes, microorganisms create gas bubbles as a byproduct. Indeed the interplay of bubbles and microorganisms is captured in the origin of the word fermentation, which is derived from the Latin word ‘fervere’, or to boil. More recently, the importance of bubbles on the transfer of microorganisms has been appreciated. In the 1940s, scientists linked red tide syndrome to toxins aerosolized by bursting bubbles in the ocean. Other more deadly illnesses, such as Legionnaires’ disease have been linked since.
Figure 1: Bubble formation during wave breaking resulting in the white foam made of a myriad of bubbles of various sizes. (Walls, Bird, and Bourouiba, 2014, used with permission)
Bubbles are formed whenever gas is completely surrounded by an immiscible liquid. This encapsulation can occur when gas boils out of a liquid or when gas is injected or entrained from an external source, such as a breaking wave. The liquid molecules are attracted to each other more than they are to the gas molecules, and this difference in attraction leads to a surface tension at the gas-liquid interface. This surface tension minimizes surface area so that bubbles tend to be spherical when they rise and rapidly retract when they pop.
Figure 2: Schematic example of Bubble formation (a), rise (b), surfacing (c), rupture (d), film droplet formation (e), and finally jet droplet formation (f) illustrating the life of bubbles from birth to death. (Bird, 2014, used with permission)
When microorganisms are near a bubble, they can interact in several ways. First, a rising bubble can create a flow that can move, mix, and stress the surrounding cells. Second, some of the gas inside the bubble can dissolve into the surrounding fluid, which can be important for respiration and gas exchange. Microorganisms can likewise influence a bubble by modifying its surface properties. Certain microorganisms secrete surfactant molecules, which like soap move to the liquid-gas interface and can locally lower the surface tension. Microorganisms can also adhere and stick on this interface. Thus, a submerged bubble travelling through the bulk can scavenge surrounding particulates during its journey, and lift them to the surface.
When a bubble reaches a surface (Figure 2c), such as the air-sea interface, it creates a thin, curved film that drains and eventually pops. In Figure 3, a sequence of images shows a bubble before (Fig 3a), during, and after rupture (Fig 3b). The schematic diagrams displayed in Fig 2c-f complement this sequence. Once a hole nucleates in the bubble film (Fig 2d), surface tension causes the film to rapidly retract and centripetal acceleration acts to destabilize the rim so that it forms ligaments and droplets. For the bubble shown, this retraction process occurs over a time of 150 microseconds, where each microsecond is a millionth of a second. The last image of the time series shows film drops launching into the surrounding air. Any particulates that became encapsulated into these film droplets, including all those encountered by the bubble on its journey through the water column, can be transported throughout the atmosphere by air currents.
Figure 3: Photographs, before, during, and after bubble ruptures. The top panel illustrated the formation of small film droplets; the bottom panel illustrates the formation of larger jet drops. (Bird, 2014, used with permission)
Another source of droplets occurs after the bubble has ruptured (Fig 3b). The events occurring after the bubble ruptures is presented in the second time series of photographs. Here the time between photographs is one milliseconds, or 1/1000th of a second. After the film covering the bubble has popped, the resulting cavity rapidly closes to minimize surface area. The liquid filling the cavity overshoots, creating an upward jet that can break up into vertically propelled droplets. These jet drops can also transport any nearby particulates, also including those scavenged by the bubble on its journey to the surface. Although both film and jet drops can vary in size, jet drops tend to be bigger.
Whether it is for the best or the worst, bubbles are ubiquitous in our everyday life. They can expose us to diseases and harmful chemicals, or tickle our palate with fresh scents and yeast aromas, such as those distinctly characterizing a glass of champagne. Bubbles are the messenger that can connect the depth of the waters to the air we breathe and illustrate the inherent interdependence and connectivity that we have with our surrounding environment.
How can sacoglossan sea slugs perform photosynthesis – a process usually associated with plants?
Kleptoplasty describes a special type of endosymbiosis where a host organism retain photosynthetic organelles from their algal prey. Kleptoplasty is widespread in ciliates and foraminifera; however, within Metazoa animals (animals having the body composed of cells differentiated into tissues and organs, and usually a digestive cavity lined with specialized cells), sacoglossan sea slugs are the only known species to harbour functional plastids. This characteristic gives these sea slugs their very special feature.
The “stolen” chloroplasts are acquired by the ingestion of macro algal tissue and retention of undigested functional chloroplasts in special cells of their gut. These “stolen” chloroplasts (thereafter named kleptoplasts) continue to photosynthesize for varied periods of time, in some cases up to one year.
In our study, we analyzed the pigment profile of Elysia viridis in order to evaluate appropriate measures of photosynthetic activity.
The pigments siphonaxanthin, trans and cis-neoxanthin, violaxanthin, siphonaxanthin dodecenoate, chlorophyll (Chl) a and Chl b, ε,ε- and β,ε-carotenes, and an unidentified carotenoid were observed in all Elysia viridis. With the exception of the unidentified carotenoid, the same pigment profile was recorded for the macro algae C. tomentosum (its algal prey).
In general, carotenoids found in animals are either directly accumulated from food or partially modified through metabolic reactions. Therefore, the unidentified carotenoid was most likely a product modified by the sea slugs since it was not present in their food source.
Image credit: Lettuce sea slug, by Laszlo Ilyes. CC-BY-SA-2.0 via Flickr.
Pigments characteristic of other macro algae present in the sampling locations were not detected inthe sea slugs. These results suggest that these Elysia viridis retained chloroplasts exclusively from C. tomentosum.
In general, the carotenoids to Chl a ratios were significantly higher in Elysia viridis than in C. tomentosum. Further analysis using starved individuals suggests carotenoid retention over Chlorophylls during the digestion of kleptoplasts. It is important to note that, despite a loss of 80% of Chl a in Elysia viridis starved for two weeks, measurements of maximum capacity of performing photosynthesis indicated a decrease of only 5% of the photosynthetic capacity of kleptoplasts that remain functional.
This result clearly illustrates that measurement of photosynthetic activity using this approach can be misleading when evaluating the importance of kleptoplasts for the overall nutrition of the animal.
Finally, concentrations of violaxanthin were low in C. tomentosum and Elysia viridis and no detectable levels of antheraxanthin or zeaxanthin were observed in either organism. Therefore, the occurrence of a xanthophyll cycle as a photoregulatory mechanism, crucial for most photosynthetic organisms, seems unlikely to occur in C. tomentosum and Elysia viridis but requires further research.
I was sorting through my TBF (to be finished) files this morning and came across a little ditty that I’d like to share. I have many files like this one; bits of story ideas, entire chapters that sounded good at the time but fell by the wayside when a more exciting project came along, or things that I never finished researching for one reason or another.
This is only the first page or so of a story’s first draft. There is much more at home that follows this. What I’ve decided to do is ask you if you think I should spend valuable time to finish it. Do you think it could spark enough interest to encourage a reader to turn pages? Can you easily envision possible scenarios for the events hinted at by the writer? Would you be curious enough to turn pages?
I’m taking this step because I have so little invested in this wee sample. I could easily finish it, or, I could ignore it and let it fade into the distance of the past. You tell me how I should treat this prospective story.
As I’ve said, I have little invested in it. I’d much rather have honest opinions than sugar-coated rhetoric that means nothing.
Ever wonder if other people’s lives were punctuated by oddities like yours? Let me tell you; you’re not alone. Take it from the Queen of Weirdness, everyone’s had their lives polka-dotted by those little quirks that have little or no explanation.
During my life I’ve experienced so many oddities that flamed across my reality that many times I felt like I was living an episode of the Twilight Zone. I suppose that’s why I knew I just had to write this small, focused catalog of incidents. I wanted to assure others that just because they’d never seen anything like what had suddenly flipped through their lives didn’t mean it wasn’t possible.
After all, just because someone’s paranoid doesn’t mean that there isn’t someone out to get them, and that’s my motto about weirdness. The Creator put a lot of stuff out there in the heavens and on Earth. You or I could be a little slow on the uptake and missed something along the way. And occasionally that something drops by to introduce itself.
I doubt there’s much in the way of weirdness that I have seen. Take ball lightning, for instance. I was twelve the first time I saw it. Goosebumps coursed down my spine, leaving entire meadows of their offspring on my arms. The thing that caused me the most fright was that it moved when it was observed, took a fancy to certain people in the room, and then gradually faded from sight without emitting a sound.
Now that you’ve had a chance to go through the beginning, what do you think? Please let me know. Is there enough here to create a worthy story or not. Give me your comments with opinions. Don’t be shy.
I was sorting through my TBF (to be finished) files this morning and came across a little ditty that I’d like to share. I have many files like this one; bits of story ideas, entire chapters that sounded good at the time but fell by the wayside when a more exciting project came along, or things that I never finished researching for one reason or another.
This is only the first page or so of a story’s first draft. There is much more at home that follows this. What I’ve decided to do is ask you if you think I should spend valuable time to finish it. Do you think it could spark enough interest to encourage a reader to turn pages? Can you easily envision possible scenarios for the events hinted at by the writer? Would you be curious enough to turn pages?
I’m taking this step because I have so little invested in this wee sample. I could easily finish it, or, I could ignore it and let it fade into the distance of the past. You tell me how I should treat this prospective story.
As I’ve said, I have little invested in it. I’d much rather have honest opinions than sugar-coated rhetoric that means nothing.
Ever wonder if other people’s lives were punctuated by oddities like yours? Let me tell you; you’re not alone. Take it from the Queen of Weirdness, everyone’s had their lives polka-dotted by those little quirks that have little or no explanation.
During my life I’ve experienced so many oddities that flamed across my reality that many times I felt like I was living an episode of the Twilight Zone. I suppose that’s why I knew I just had to write this small, focused catalog of incidents. I wanted to assure others that just because they’d never seen anything like what had suddenly flipped through their lives didn’t mean it wasn’t possible.
After all, just because someone’s paranoid doesn’t mean that there isn’t someone out to get them, and that’s my motto about weirdness. The Creator put a lot of stuff out there in the heavens and on Earth. You or I could be a little slow on the uptake and missed something along the way. And occasionally that something drops by to introduce itself.
I doubt there’s much in the way of weirdness that I have seen. Take ball lightning, for instance. I was twelve the first time I saw it. Goosebumps coursed down my spine, leaving entire meadows of their offspring on my arms. The thing that caused me the most fright was that it moved when it was observed, took a fancy to certain people in the room, and then gradually faded from sight without emitting a sound.
Now that you’ve had a chance to go through the beginning, what do you think? Please let me know. Is there enough here to create a worthy story or not. Give me your comments with opinions. Don’t be shy.
It’s compelling…definitely worth finishing.
That’s one vote for finishing. Thanks, Pen. I’d always thought of this as humor based as well as something that could put a twist in a cat’s tail.