Archive for the ‘Harvard’ Category


The most unusual colors from Harvard’s storied pigment library include beetle extracts, poisonous metals, and human mummies.

Today, every color imaginable is at your fingertips. You can peruse paint swatches at hardware stores, flip through Pantone books, and fuss with the color finder that comes with most computer programs, until achieving the hue of your heart’s desire. But rewind to a few centuries ago and finding that one specific color might have meant trekking to a single mineral deposit in remote Afghanistan—as was the case with lapis lazuli, a rock prized for its brilliant blue hue, which made it more valuable than gold in medieval times.

The history of pigments goes back to prehistoric times, but much of what we know about how they relate to the art world comes from Edward Forbes, a historian and director of the Fogg Art Museum at Harvard University from 1909 to 1944. Considered the father of art conservation in the United States, Forbes traveled around the world amassing pigments in order to authenticate classical Italian paintings. Over the years, the Forbes Pigment Collection—as his collection came to be known—grew to more than 2,500 different specimens, each with its own layered backstory on its origin, production, and use.

Today, the collection is used mostly for scientific analysis, providing standard pigments to compare to unknowns. Narayan Khandekar is the director of the Straus Center for Conservation and Technical Studies at the Harvard Art Museums and the collection’s custodian. For the last 10 years, Khandekar has rebuilt the collection to include modern pigments to better analyze 20th century and contemporary art.

A lot has changed in the art world since painters worked with “colormen”—as tradesmen in dyes and pigments were known—to obtain their medium. The commercialization of paints has transformed that process. “Artists today will use anything to get the idea that’s in their head into a physical form,” Khandekar says. “It could be pieces of plastic. It could be cans of food. It could be anything. We need to be able to identify lots of different materials that are industrially produced as well as things that are produced specifically for artists’ use.”

The way he describes his work researching and cataloging pigments is akin to detective work. “We use our instruments in the same way that forensic scientists do,” Khandekar says. “We examine and find out what we can about the key compounds that will tell us the material’s origin.” But instead of tools such as DNA analysis, he and his team of conservation scientists use techniques such as Raman spectroscopy, mass spectrometry, gas chromatography, and electron microscopy to map out the precise chemical composition of a pigment.

For example, their work was instrumental in proving that a Jackson Pollock painting “rediscovered” in 2007 was actually a fake, after pigment analysis revealed that a specific red color was manufactured 20 years after the artist’s death. The color, Red 254, was a by-product of a chemical reaction first documented in 1974; it’s also nicknamed
“Ferrari red.”

“Every pigment has its own story,” Khandekar says. With that in mind, we asked him to share the stories of 10 of the rarest and most interesting pigments in the Forbes collection.


Synthetic Ultramarine

“This was discovered in 1826 as the result of a contest. In a way it is like discovering how to make gold as artists no longer had to buy natural ultramarine at great cost.”

Mummy Brown
“People would harvest mummies from Egypt and then extract the brown resin material that was on the wrappings around the bodies and turn that into a pigment. It’s a very bizarre kind of pigment, I’ve got to say, but it was very popular in the 18th and 19th centuries.”

Brazilwood
“Brazilwood is any of several tropical trees of the senna genus. Its hard, red-color wood has had limited use for violins, bows, veneer, and high-quality furniture. The wood contains the colorant brasilin, which gives a deep-red to brownish color. Brazilwood dye has been used for textile and leather dyes, inks, paints, varnish tints, and wood stains.”

Quercitron
“A yellow vegetable dye, quercitron is extracted from the black or dark brown bark of the black oak, Quercus velutina, that is native to the Eastern and Midwestern parts of the United States.”

Annatto
“The lipstick plant—a small tree, Bixa orellana, native to Central and South America—produces annatto, a natural orange dye. Seeds from the plant are contained in a pod surrounded with a bright red pulp. Currently, annatto is used to color butter, cheese, and cosmetics.”

Lapis Lazuli
“People would mine it in Afghanistan, ship it across Europe, and it was more expensive that gold so it would have its own budget line on a commission.”

Dragon’s Blood
“It has a great name, but it’s not from dragons. [The bright red pigment] is from the rattan palm.”

Cochineal
“This red dye comes from squashed beetles, and it’s used in cosmetics and food.”

Cadmium Yellow
“Cadmium yellow was introduced in the mid 19th century. It’s a bright yellow that many impressionists used. Cadmium is a heavy metal, very toxic. In the early 20th century, cadmium red was introduced. You find these pigments used in industrial processes. Up until the 1970s, Lego bricks had cadmium pigment in them.”


Emerald Green

“This is made from copper acetoarsenite. We had a Van Gogh with a bright green background that was identified as emerald green. Pigments used for artists’ purposes can find their way into use in other areas as well. Emerald green was used as an insecticide, and you often see it on older wood that would be put into the ground, like railroad ties.”

http://www.fastcodesign.com/3058058/the-harvard-vault-that-protects-the-worlds-rarest-colors

On one side of the stage at a maximum-security prison here sat three men incarcerated for violent crimes.

On the other were three undergraduates from Harvard College.

After an hour of fast-moving debate Friday, the judges rendered their verdict.

The inmates won.

The audience burst into applause. That included about 75 of the prisoners’ fellow students at the Bard Prison Initiative, which offers a rigorous college experience to men at Eastern New York Correctional Facility, in the Catskills.

The debaters on both sides aimed to highlight the academic power of a program, part of Bard College in Annandale-on-Hudson, N.Y., that seeks to give a second chance to inmates hoping to build a better life.

Ironically, the inmates had to promote an argument with which they fiercely disagreed. Resolved: “Public schools in the United States should have the ability to deny enrollment to undocumented students.”

Carlos Polanco, a 31-year-old from Queens in prison for manslaughter, said after the debate that he would never want to bar a child from school and he felt forever grateful he could pursue a Bard diploma. “We have been graced with opportunity,” he said. “They make us believe in ourselves.”

Judge Mary Nugent, leading a veteran panel, said the Bard team made a strong case that the schools attended by many undocumented children were failing so badly that students were simply being warehoused. The team proposed that if “dropout factories” with overcrowded classrooms and insufficient funding could deny these children admission, then nonprofits and wealthier schools would step in and teach them better.

Ms. Nugent said the Harvard College Debating Union didn’t respond to parts of that argument, though both sides did an excellent job.

The Harvard team members said they were impressed by the prisoners’ preparation and unexpected line of argument. “They caught us off guard,” said Anais Carell, a 20-year-old junior from Chicago.

The prison team had its first debate in spring 2014, beating the U.S. Military Academy at West Point, N.Y. Then, it won against a nationally ranked team from the University of Vermont and in April lost a rematch against West Point.

Preparing has its challenges. Inmates can’t use the Internet for research. The prison administration must approve requests for books and articles, which can take weeks.

In the morning before the debate, team members talked of nerves and their hope that competing against Harvard—even if they lost—would inspire other inmates to pursue educations.

“If we win, it’s going to make a lot of people question what goes on in here,” said Alex Hall, a 31-year-old from Manhattan convicted of manslaughter. “We might not be as naturally rhetorically gifted, but we work really hard.”

Ms. Nugent said it might seem tempting to favor the prisoners’ team, but the three judges have to justify their votes to each other based on specific rules and standards.

“We’re all human,” she said. “I don’t think we can ever judge devoid of context or where we are, but the idea they would win out of sympathy is playing into pretty misguided ideas about inmates. Their academic ability is impressive.”

The Bard Prison Initiative, begun in 2001, aims to give liberal-arts educations to talented, motivated inmates. Program officials say about 10 inmates apply for every spot, through written essays and interviews.

There is no tuition. The initiative’s roughly $2.5 million annual budget comes from private donors and includes money it spends helping other programs follow its model in nine other states.

Last year Gov. Andrew Cuomo, a Democrat, proposed state grants for college classes for inmates, saying that helping them become productive taxpayers would save money long-term. He dropped the plan after attacks from Republican politicians who argued that many law-abiding families struggled to afford college and shouldn’t have to pay for convicted criminals to get degrees.

The Bard program’s leaders say that of more than 300 alumni who earned degrees while in custody, less than 2% returned to prison within three years, the standard time frame for measuring recidivism.

In New York state as a whole, by contrast, about 40% of ex-offenders end up back in prison, mostly because of parole violations, according to the New York Department of Corrections and Community Supervision.

http://www.wsj.com/articles/an-unlikely-debate-prison-vs-harvard-1442616928

Getting really angry might be more dangerous than you think.

A new study found people who experienced severe anger outbursts were more at risk for cardiovascular events in the two hours following the outbursts compared to those who remained calm.

“The relative risk was similar for people who had known pre-existing heart disease and those who didn’t,” says Dr. Murray A. Mittleman, senior study author and an associate professor of medicine at Harvard Medical School.

The study was designed so that each patient was compared to his or her own baseline risk. “A person with pre-existing heart disease or cardiovascular disease, the absolute risk they are incurring is much greater than (that of) a person without cardiovascular disease or risk factors,” Mittleman says.
“If we look at somebody at higher risk for having cardiovascular events, and they get angry multiple times a day, this can lead to 650 extra heart attacks per year out of 10, 000 a year,” he says. “When we look at a person who is relatively low risk, but if they do have these episodes of anger fairly frequently, we estimate there would be about 150 extra heart attacks out of 10,000 a year.”

Smoking, high cholesterol, high blood pressure, being overweight and having diabetes are all risk factors for cardiovascular disease. An estimated 17 million people worldwide die of cardiovascular diseases, particularly heart attacks and strokes, each year, according to the Centers for Disease Control and Prevention.

The study published Monday in the European Heart Journal was a data analysis looking at nine studies where anger and cardiovascular events were self-reported over nearly two decades. The study found a 4.74 times higher risk of MI (myocardial infarction, or heart attack) or ACS (acute coronary syndrome, where the heart muscle doesn’t get enough oxygen-rich blood) following outbursts of anger.

“Anger causes our heart rate to increase through the sympathetic nervous system and causes our stress hormones to become elevated (the fight or flight mechanism),” says Dr. Mariell Jessup, president of the American Heart Association and medical director of the Penn Heart and Vascular Center at the University of Pennsylvania. “We breathe faster, all of which may trigger undesirable reactions in our blood pressure or in our arteries.”

This disruption may mean the heart or the brain doesn’t get the blood and oxygen they need resulting in a heart attack or a stroke, she says.

Researchers suggest more needs to be done to come up with effective interventions to prevent cardiovascular events triggered by anger outbursts. The American Heart Association suggests regular physical activity, finding a way to relax or talking with friends to help reduce stress and anger.

Mittleman suggests the best way to lower your risk for a heart attack or stroke during an angry outburst is to lower your overall baseline level of risk – exercise, eat healthy and don’t smoke – and then find ways to cope with stress and anger.

http://thechart.blogs.cnn.com/2014/03/03/angry-outbursts-may-raise-heart-attack-stroke-risk/?hpt=hp_t2

irish volcano

By Matt McGrath

Environment correspondent, BBC News

Researchers have been able to trace the impact of volcanic eruptions on the climate over a 1200 year period by assessing ancient Irish texts.

The international team compared entries in these medieval annals with ice core data indicating volcanic eruptions.

Of 38 volcanic events, 37 were associated with directly observed cold weather extremes recorded in the chronicles.

The report is published in the journal Environmental Research Letters.

In the dim light of the Dark Ages, the Irish literary tradition stands out like a beacon.

At monastic centres across the island, scribes recorded significant events such as feast days, obituaries and descriptions of extreme cold and heat.

These chronicles are generally known as the Irish Annals and in this report, scientists and historians have looked at 40,000 entries in the texts dating from AD431 to 1649.

The researchers also looked at the Greenland Ice Sheet Project (GISP2) ice-core data.

When volcanoes erupt, they produce sulphate aerosol particles which down the centuries have been deposited on and frozen in ice sheets, leaving an extremely accurate temporal record of the event.

Scientists say these particles reflect incoming sunlight and can cause a temporary cooling of the Earth’s surface. In a country with a mild maritime climate like Ireland, these colder events would have a significant impact.

When the weather that is cold enough to allow you to walk over a lake in Ireland, it is pretty unusual,” lead author Dr Francis Ludlow, from Harvard University, told BBC News.

“When it happened, it was remarkable enough to be recorded pretty consistently.”

The scientists in the team identified 48 volcanic eruptions in the time period spanning 1,219 years. Of these, 38 were associated closely in time with extreme weather events identified in the Irish texts.

“These eruptions occur and they override existing climate patterns for a period of two or three years,” said Dr Ludlow.

“And it is clear from the sources that they cause a lot of devastation among societies at the time – whether it was the mass mortality of domestic animals or humans, or indirectly by causing harvest failure.”

The research team believe the texts are accurate as the annals also record solar and lunar eclipses which can be compared with other contemporary sources.

The keen recording of weather though had another motivation.

“A lot of these scribes are working in monasteries, in some time periods they are interpreting these weather events as divine omens or portents as signals of the coming of the last days,” said Dr Ludlow.

“That was one of their motivations so we are able to use the records that were created for a completely different purpose that the scribes would never have conceived.”

The researchers say that one expected effect of volcanic eruptions that occur in tropical regions is to make for milder winters in northern latitudes.

But in this study, they found several instances of these type of eruptions causing extremely cold winters in Ireland. The team believes their work shows the complex nature of volcanic impacts on climate, and they say there are lessons for the future in the ancient texts.

“That tells us a lot about what sort of weather we might expect in the British Isles when the next big eruption goes off,” said Dr Ludlow.

“We might want to buy a bit more salt for the roads.”

http://www.bbc.co.uk/news/science-environment-22786179

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

Protein_CACNA1C_PDB_2be6
Structure of the CACNA1C gene product, a calcium channel named Cav1.2, which is one of 4 genes that has now been found to be genetically held in common amongst schizophrenia, bipolar disorder, autism, major depression and attention deficit hyperactivity disoder. Groundbreaking work on the role of this protein on anxiety and other forms of behavior related to mental illness has previously been established in the Rajadhyaksha laboratory at Weill Cornell Medical Center.
http://weill.cornell.edu/research/arajadhyaksha/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3481072/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192195/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3077109/

From the New York Times:
The psychiatric illnesses seem very different — schizophrenia, bipolar disorder, autism, major depression and attention deficit hyperactivity disorder. Yet they share several genetic glitches that can nudge the brain along a path to mental illness, researchers report. Which disease, if any, develops is thought to depend on other genetic or environmental factors.

Their study, published online Wednesday in the Lancet, was based on an examination of genetic data from more than 60,000 people worldwide. Its authors say it is the largest genetic study yet of psychiatric disorders. The findings strengthen an emerging view of mental illness that aims to make diagnoses based on the genetic aberrations underlying diseases instead of on the disease symptoms.

Two of the aberrations discovered in the new study were in genes used in a major signaling system in the brain, giving clues to processes that might go awry and suggestions of how to treat the diseases.

“What we identified here is probably just the tip of an iceberg,” said Dr. Jordan Smoller, lead author of the paper and a professor of psychiatry at Harvard Medical School and Massachusetts General Hospital. “As these studies grow we expect to find additional genes that might overlap.”

The new study does not mean that the genetics of psychiatric disorders are simple. Researchers say there seem to be hundreds of genes involved and the gene variations discovered in the new study confer only a small risk of psychiatric disease.

Steven McCarroll, director of genetics for the Stanley Center for Psychiatric Research at the Broad Institute of Harvard and M.I.T., said it was significant that the researchers had found common genetic factors that pointed to a specific signaling system.

“It is very important that these were not just random hits on the dartboard of the genome,” said Dr. McCarroll, who was not involved in the new study.

The work began in 2007 when a large group of researchers began investigating genetic data generated by studies in 19 countries and including 33,332 people with psychiatric illnesses and 27,888 people free of the illnesses for comparison. The researchers studied scans of people’s DNA, looking for variations in any of several million places along the long stretch of genetic material containing three billion DNA letters. The question: Did people with psychiatric illnesses tend to have a distinctive DNA pattern in any of those locations?

Researchers had already seen some clues of overlapping genetic effects in identical twins. One twin might have schizophrenia while the other had bipolar disorder. About six years ago, around the time the new study began, researchers had examined the genes of a few rare families in which psychiatric disorders seemed especially prevalent. They found a few unusual disruptions of chromosomes that were linked to psychiatric illnesses. But what surprised them was that while one person with the aberration might get one disorder, a relative with the same mutation got a different one.

Jonathan Sebat, chief of the Beyster Center for Molecular Genomics of Neuropsychiatric Diseases at the University of California, San Diego, and one of the discoverers of this effect, said that work on these rare genetic aberrations had opened his eyes. “Two different diagnoses can have the same genetic risk factor,” he said.

In fact, the new paper reports, distinguishing psychiatric diseases by their symptoms has long been difficult. Autism, for example, was once called childhood schizophrenia. It was not until the 1970s that autism was distinguished as a separate disorder.

But Dr. Sebat, who did not work on the new study, said that until now it was not clear whether the rare families he and others had studied were an exception or whether they were pointing to a rule about multiple disorders arising from a single genetic glitch.

“No one had systematically looked at the common variations,” in DNA, he said. “We didn’t know if this was particularly true for rare mutations or if it would be true for all genetic risk.” The new study, he said, “shows all genetic risk is of this nature.”

The new study found four DNA regions that conferred a small risk of psychiatric disorders. For two of them, it is not clear what genes are involved or what they do, Dr. Smoller said. The other two, though, involve genes that are part of calcium channels, which are used when neurons send signals in the brain.

“The calcium channel findings suggest that perhaps — and this is a big if — treatments to affect calcium channel functioning might have effects across a range of disorders,” Dr. Smoller said.

There are drugs on the market that block calcium channels — they are used to treat high blood pressure — and researchers had already postulated that they might be useful for bipolar disorder even before the current findings.

One investigator, Dr. Roy Perlis of Massachusetts General Hospital, just completed a small study of a calcium channel blocker in 10 people with bipolar disorder and is about to expand it to a large randomized clinical trial. He also wants to study the drug in people with schizophrenia, in light of the new findings. He cautions, though, that people should not rush out to take a calcium channel blocker on their own.

“We need to be sure it is safe and we need to be sure it works,” Dr. Perlis said.

http://www.nytimes.com/2013/03/01/health/study-finds-genetic-risk-factors-shared-by-5-psychiatric-disorders.html?hp&_r=1&

volcano1

It has long been known that volcanic activity can cause short-term variations in climate. Now, researchers at the GEOMAR Helmholtz Centre for Ocean Research Kiel (Germany), together with colleagues from Harvard University have found evidence that the reverse process also occurs: Climate affects volcanic activity. “In times of global warming, the glaciers are melting on the continents relatively quickly. At the same time the sea level rises. The weight on the continents decreases, while the weight on the oceanic tectonic plates increases. The stress changes within in the earth to open more routes for ascending magma” says geophysicist Dr Marion Jegen from GEOMAR, who participated in the study. The rate of global cooling at the end of the warm phases is much slower, so there are less dramatic stress changes during these times.

“If you follow the natural climate cycles, we are currently at the end of a really warm phase. Therefore, things are volcanically quieter now. The impact from man-made warming is still unclear based on our current understanding” says GEOMAR volcanologist Dr Steffen Kutterolf, who has been with SFB 574 since its founding.
In 1991, it was a disaster for the villages nearby the erupting Philippine volcano Pinatubo. But the effects were felt even as far away as Europe. The volcano threw up many tons of ash and other particles into the atmosphere causing less sunlight than usual to reach the Earth’s surface. For the first few years after the eruption, global temperatures dropped by half a degree. In general, volcanic eruptions can have a strong short-term impact on climate. Conversely, the idea that climate may also affect volcanic eruptions on a global scale and over long periods of time is completely new.

Researchers at GEOMAR Helmholtz Centre for Ocean Research Kiel (Germany) and Harvard University in Massachusetts (USA) have now found strong evidence for this relationship from major volcanic eruptions around the Pacific Ocean over the past 1 million years. They have presented their results in the latest issue of the international journal Geology.

For more than ten years the project has been extensively exploring volcanoes of Central America. “Among others pieces of evidence, we have observations of ash layers in the seabed and have reconstructed the history of volcanic eruptions for the past 460,000 years,” says Kutterolf. Particular patterns started to appear. “There were periods when we found significantly more large eruptions than in others” says Kutterolf.

After comparing these patterns with the climate history, there was an amazing match. The periods of high volcanic activity followed fast, global temperature increases and associated rapid ice melting. To expand the scope of the discoveries, Dr Kutterolf and his colleagues studied other cores from the entire Pacific region. These cores had been collected as part of the International Integrated Ocean Drilling Program (IODP) and its predecessor programmes. They record more than a million years of the Earth’s history.

“In fact, we found the same pattern from these cores as in Central America” says Jegen. Together with colleagues at Harvard University, the geologists and geophysicists searched for a possible explanation. They found it with the help of geological computer models.

The next step is to investigate shorter-term historical variations to better understand implications for the present day.

For more information: Kutterolf, S., M. Jegen, J. X. Mitrovica, T. Kwasnitschka, A. Freundt, P. J. Huybers (2012): A detection of Milankovitch frequencies in global volcanic activity. Geology, G33419.1, dx.doi.org/10.1130/G33419.1 Journal reference: Geology

http://www.dailygalaxy.com/my_weblog/2012/12/ecoalert-strong-link-between-climate-change-and-volcanic-eruptions-discovered.html

palm

For centuries, humans have been exploring, researching, and, in some cases, discovering how to stave off life-threatening diseases, increase life spans, and obtain immortality. Biologists, doctors, spiritual gurus, and even explorers have pursued these quests — one of the most well-known examples being the legendary search by Ponce de León for the “Fountain of Youth.” Yet the key to longevity may not lie in a miraculous essence of water, but rather in the structure and function of cells within a plant — and not a special, mysterious, rare plant, but one that we may think of as being quite commonplace, even ordinary: the palm.

As an honors botany student at the University of Leeds, P. Barry Tomlinson wrote a prize-winning essay during his final year titled, “The Span of Life.” Fifty years later, Tomlinson (now a Distinguished Professor at The Kampong Garden of the National Tropical Botanical Garden, Miami, FL) teamed up with graduate student Brett Huggett (Harvard University, MA) to write a review paper exploring the idea that palms may be the longest-lived tree, and whether this might be due to genetic underpinnings. Having retained his essay in his personal files, Tomlinson found that it provided an excellent literature background for working on the question of cell longevity in relation to palms. Together, Tomlinson and Huggett published their review in the December issue of the American Journal of Botany.

A component of an organism’s life span that biologists have been particularly interested in is whether longevity is genetically determined and adaptive. For botanists, discovering genetic links to increasing crop production and the reproductive lifespan of plants, especially long-lived ones such as trees, would be invaluable.

In their paper, Tomlinson and Huggett emphasize that in many respects, an organisms’ life span, or longevity, is determined by the period of time in which its cells remain functionally metabolically active. In this respect, plants and animals differ drastically, and it has to do with how they are organized — plants are able to continually develop new organs and tissues, whereas animals have a fixed body plan and are not able to regenerate senescing organs. Thus, plants can potentially live longer than animals.

“The difference in potential cell longevity in plants versus animals is a significant point,” states Tomlinson. “It is important to recognize that plants, which are so often neglected in modern biological research, can be informative of basic cell biological features in a way that impacts human concern at a fundamental level.”

The authors focused their review on palm trees because palms have living cells that may be sustained throughout an individual palm’s lifetime, and thus, they argue, may have some of the longest living cells in an organism. As a comparison, in most long-lived trees, or lignophytes, the main part, or trunk, of the tree is almost entirely composed of dead, woody, xylem tissues, and in a sense is essentially a supportive skeleton of the tree with only an inner ring of actively dividing cells. For example, the skeleton of Pinus longaeva may be up to 3000 years old, but the active living tissues can only live less than a century.

In contrast, the trunks of palms consist of cells that individually live for a long time, indeed for the entire life of an individual.

Which brings up the question of just how long can a palm tree live? The authors point out that palm age is difficult to determine, primarily because palms do not have secondary growth and therefore do not put down annual or seasonal growth rings that can easily be measured. However, age can be quite accurately assessed based on rate of leaf production and/or visible scars on the trunk from fallen leaves. Accordingly, the authors found that several species of palm have been estimated to live as long as 100 and even up to 740 years. The important connection here is that while the “skeleton” of the palm may not be as old as a pine, the individual cells in its trunk lived, or were metabolically active, as long as, or longer than those of the pine’s.

Most plants, in addition to increasing in height as they age, also increase in girth, putting down secondary vascular tissue in layers both on the inner and outer sides of the cambium as they grow. However, palms do not have secondary growth, and there is no addition of secondary vascular tissue. Instead, stem tissues are laid down in a series of interconnected vascular bundles — thus, not only is the base of the palm the oldest and the top the youngest, but these tissues from old to young, from base to top, must also remain active in order to provide support and transport water and nutrients throughout the tree.

Indeed, the authors illustrate this by reviewing evidence of sustained primary growth in two types of palms, the coconut and the sago palm. These species represent the spectrum in tissue organization from one where cells are relatively uniform and provide both hydraulic and mechanical functions (the coconut) to one where these functions are sharply divided with the inner cells functioning mainly for transporting water and nutrients and the outer ones for mechanical support (the sago palm). This represents a progression in specialization of the vascular tissues.

Moreover, there is evidence of continued metabolic activity in several types of tissues present in the stems of palms, including vascular tissue, fibers, ground tissue, and starch storage. Since the vascular tissues in palms are nonrenewable, they must function indefinitely, and Tomlinson and Huggett point out that sieve tubes and their companion cells are remarkable examples of cell longevity as they maintain a long-distance transport function without replacement throughout the life of the stem, which could be for centuries.

Despite several unique characteristics of palms, including the ability to sustain metabolically active cells in the absence of secondary tissues, seemingly indefinitely, unlike conventional trees, in which metabolically active cells are relatively short-lived, the authors do not conclude that the extended life span of palms is genetically determined.

“We are not saying that palms have the secret of eternal youth, and indeed claim no special chemical features which allows cells in certain organisms to retain fully differentiated cells with an indefinite lifespan,” states Tomlinson. “Rather, we emphasize the distinctive developmental features of palm stems compared with those in conventional trees.”

Tomlinson indicates that this reflects the neglect of the teaching of palm structure in modern biology courses. “This paper raises incompletely understood aspects of the structure and development of palms, emphasizing great diversity in these features,” he concludes. “This approach needs elaborating in much greater detail, difficult though the subject is in terms of conventional approaches to plant anatomy.”

Journal Reference:

1.P. B. Tomlinson, B. A. Huggett. Cell longevity and sustained primary growth in palm stems. American Journal of Botany, 2012; 99 (12): 1891 DOI: 10.3732/ajb.1200089

http://www.sciencedaily.com/releases/2012/12/121219092842.htm