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francium

Francium is a naturally occurring element–a highly radioactive alkali metal with one valence electron. At any given moment there is 20-30 grams of Francium (about an ounce) present on Earth. This tiny sample is found in the form of individual atoms located within uranium and thorium ores around the Earth’s crust.   The half-life of the longest-lived isotope of francium is only 22 minutes. The weird transient metal continuously vanishes (decaying into astatine, radium, or radon)–only to be continuously replaced when actinium-227 decays into francium-223.

Marguerite_Perey

Marguerite Catherine Perey (19 October 1909 – 13 May 1975), French physicist

How did we ever even find out about this stuff if it only exists as 20 grams of individual atoms scattered around the entire world like evanescent Easter eggs? I’m glad you asked! It was discovered by a French woman in 1939. Marguerite Catherine Perey (1909 – 1975) was born in 1909 in Villemomble, France (just outside Paris)–where Marie Curie’s Radium Institute also happened to be located. Perey aspired to be a medical doctor, but her family fell into financial difficulty so, at the age of 19, she took a job at a local spot–working directly for Marie Curie. Curie died of exotic cancer in 1934, but Perey kept up her mentor’s work purifying and studying actinium and looking for a theorized “eka-caesium” (a heretofore unknown alkali metal with an atomic number of 87). Through her methodic and painstaking work and observations, Perey discovered it just as World War II. broke out. Francium was the last element discovered in nature. The rest have been synthesized in labs.

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Marguerite Perey (second from left) at the Curie laboratory in 1930

After discovering an entirely new atom, Perey finally received a grant to pursue her university studies, and she received her PhD from the Sorbonne in 1946. In 1960 she became an officer of the Legion of Honor. She founded the laboratory which ultimately grew into became the Laboratory of Nuclear Chemistry in the Center for Nuclear Research and she was the first woman to be elected to the French Académie des Sciences.

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True to her original dream of helping people as a doctor, Perey hoped that francium would help diagnose cancer and make the disease more treatable, but sadly, francium itself was carcinogenic (which is something to remember, if you find an atom of it sitting in some uranium ore). In her late life, Perey developed bone cancer which eventually killed her–a dark fruit of her pioneering research.

I mention francium this week, not because of its name (coincidentally, it is named after the great nation of France), but because of the life of the scientist who discovered it. Marguerite Catherine Perey had to struggle against prejudice and steroetypes, but she was able to overcome them and move to the foremost ranks of scientists and leaders of France. Her research helped that country become a nuclear leader (which it still is) and helped humankind better understand the nature of chemistry and physics.

Aplysia californica (The California Sea Hare)

Aplysia californica (The California Sea Hare)

Behold Aplysia californica–an extremely large sea slug which grazes on red algae along the California coast.  The mollusk is rarely found at depths deeper than 20 meters.  It grows to seventy-five cm (thirty inches) in length and weighs a whopping 7kg (15.4 lbs).  Aplysia californica belongs to a family of sea slugs known as the sea hares –so called because the two rhinophores (smelling organs) atop the creatures’ heads are fancifully said to resemble a rabbit’s ears.

Aplysia californica (photo by Chris Nelson)

Aplysia californica (photo by Chris Nelson)

Although this Pacific gastropod is interesting in its own right, the slug is of greatest importance to humankind as a research animal (like the regenerating axolotl).  Aplysia has only 20,000 neuron cells–as opposed to a human brain which contains between ten and a hundred billion–and the slug’s neurons are extremely large.  This allows neuroscientists to easily observe and assess physiological and molecular changes which take place in the cells when the slug learns something.  Aplysia research is thus at the cutting edge of neuroscience.  Nearly everything we know about the molecular basis of memory and learning started out as research with the humble gastropod.

A Cartoon of a Sea Hare Learning

A Cartoon of a Sea Hare Learning

A news piece on CNN today featured Dr. Eric Kandel of Columbia University who won the 2000 Nobel Prize in Medicine & Physiology for neural research (mainly on these slugs) and made immense headway on what is probably the great cellular biology mystery of our time.  It is a pleasure to see a science article on CNN online but it was also somewhat dismaying to see how many comments were basically “why are we wasting money on studying slugs?”  In case it is not self-evident why we are trying to discover the fundamental molecular mechanisms of memory and cognition, here is a brief and not-at-all comprehensive list.

Understanding these underlying biological processes would probably help us find therapy for neuro-degenerative disorders (such as Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease).  It might also allow us to comprehend a number of psychiatric conditions, such as schizophrenia and depression.  At some point in the future, understanding the molecular basis of memories and thoughts might also allow for the engineering of some sort of bioimplant for the nervous system.  You could learn Sanscrit by popping a chip in your head or record your nightmares via wire!   Beyond such science fiction concepts, knowing about how the brain works is an end into itself—understanding the most complicated known structure in the universe is a necessary step to building structures of greater complexity.

brain-storm

Although perhaps the politically polemicized commenters who object to studying the sea hare actually reject the creature’s sex life–which is indeed somewhat at odds with traditional notions of romance and propriety.

edus826016Like all sea hares, Aplysia californica is a hermaphrodite with both male and female reproductive organs.  Because of its physiology it can (and does!) use both sets of organs simultaneously during mating. Multiple Aplysia have been known to form chains of more than 20 animals (somewhat like pop beads) where each animal simultaneously acts as a male and female at the same time with its fore and aft partners.  Copulation lasts for many hours (or sometimes for days). One can see how the creatures’ amorous predilections might not sit well with puritans and fundamentalists, however for providing a window into molecular neurophysiology we owe this gentle sea slug a big round of thanks.

"Take a bow! Hmm, somebody teach the slug to bow."

“Take a bow! Hmm, somebody teach the slug to bow.”

The Groundhog, Marmota monax (photo by Bill Smith)

Happy Groundhog Day!  Preliminary reports coming in seem to indicate that the nation’s most eminent groundhog oracles are not seeing their shadows today (what with the continent bestriding blizzard and all).  Oddly, this is interpreted as a sign that spring will arrive early this year.  However I tend to think those groundhogs on TV are media personalities who have forgotten their rural roots.  When I lived on a farm, the concept behind the holiday was more straightforward:  if you saw an actual groundhog on Groundhog Day, then winter might indeed end early, but if you didn’t (and I never did) winter would not be over for six more weeks.  Today most non-celebrity groundhogs did not stir from their deep hibernation chambers.  We probably still have plenty of winter left.

Groundhog Day is observed on or around Candelmas, which ostensibly celebrates the presentation of Baby Jesus to the temple:   Mary and Joseph took Jesus to the Kohens & Levites to perform the redemption of the firstborn and ceremonially purchase their firstborn son’s life back from the priests (I’m not sure Jesus ever really escaped the priesthood or the temple of Solomon so maybe his parents should have gotten their money back–but that’s a different story).  Candelmas was elided with pre-Christian holidays involving the prediction of the weather by animal augury.  The holiday’s roots in America are from the Pennsylvania Germans.  Apparently in pagan Germany, the original animal weather prophets were badgers or bears.  Imagine how exciting this holiday would be if we stuffed our pompous civic officials together with a disgruntled bear who had just been prodded awake from hibernation so people could take flash photographs!

At any rate we have gotten rather far afield of the day’s celebrated weather oracle, the groundhog or woodchuck (Marmota monax) which is actually a rodent of the marmot family, Sciuridae. Marmots are large solitary ground squirrels which, like pikas, generally live in the mountains of Asia, Europe, and North America.  The groundhog is an exception among the marmots since it prefers to live on open ground or at the edge of woodlands.  The deforestation of North America for farms and subdivisions has caused groundhog population to rise.  Although groundhogs are omnivores, the bulk of their diet is vegetation such as grasses, berries, and crops.  They are gifted diggers who construct a deep burrow with multiple exits.  This burrow serves as their chief living quarters and refuge from predators.  Since groundhogs enter true hibernation, they usually also maintain a separate winter burrow (with a chamber beneath the frost line) for the sole purpose of their months-long suspended animation.

A Groundhog Enjoying a Garden

Groundhogs, however, have a deeper utility to modern humankind than as primitive weather gods.  Devoted readers will know my fascination with liver research, and groundhogs are the principal research animal used in studies of Hepatitis B and liver cancer.  Since groundhogs are prone to a similar virus in the wild, they always develop liver cancer when infected with hepatitis B.  Laboratory groundhogs have thus been responsible for many advances in understanding liver disease and pathology–including the discovery of a vaccine for Hepatitis B and the realization that immunizing against hepatitis B virus can prevent liver cancer.  Currently 350 million people around the world are suspected to have hepatitis B.  Forty percent of those infected will develop chronic liver damage or cancer.  According to the World Health Organization, an estimated 600,000 people die every year from complications related to the infection (which is more than the total number of United States citizens killed in World War I and World War II combined).  Perhaps the Groundhog should be thought of as a profound benefactor to humankind thanks to its utility as a laboratory animal.

Tenochtitlan on Lake Texcoco

Modern Mexico City, super metropolis of nine million people, was once a series of lakes.  The Aztec capital, Tenochtitlan, was located there on a network of artificial islands.  In those lakes, in countless numbers, swam the axolotl, Ambystoma mexicanum, a wholly aquatic salamander.   As mentioned in the previous post, according to Aztec mythology, the underworld god Xolotl transformed himself into an axolotl to escape being murdered.  In a wide world filled with strange animals, axolotls are particularly strange: they certainly have a whiff of the underworld as well as a hint of the divine.

Axolotl

Axolotls are neotenic.  Unlike most other amphibians, they never transform into a terrestrial organism but maintain gills and tail fins for their entire lives.  Although it seems like the axolotl should be stunted by its failure to metamorphosize, it actually grows much larger and lives much longer than the tiger salamander (a non-neotenic salamander which it is closely related to).  Adult axolotls range from nine to twelve inches and can live for up to twenty five years (although a lifespan of ten to fifteen years is more normal).  They are freshwater carnivores, hunting worms, minnows, and aquatic insects via smell.

Xolotl was the god of misfortune and bad luck is currently dogging the wild axolotl.  The lakes of the Mexican basin have been one of the most populated areas of the western hemisphere since the fourteenth century.  Axolotl tacos were a favorite meal of the inhabitants for centuries and the creature was overfished up until the twentieth century…when the lakes were drained to prevent flooding.  Now the lakes largely exist in huge pipes deep below the city and as a series of polluted channels and small reservoirs.  Not only are these remaining canals choked with pollution, but super competitive non-native fish have been introduced, most prominently the African tilapia and the Asian carp.

Axolotls are nearly extinct in the wild, and it is uncertain whether they will survive there much longer.  The animals have, however found a dark refuge which ensures their continuing existence.  Because of their neoteny, axolotls have extraordinary abilities to heal themselves.  Not only can they completely regrow lost arms and legs back to full size and function, they can also regenerate damaged vital organs–including portions of their brains.  Axolotls do not heal by scarring, but seem to use some more fundamental ability to regenerate.  Of course these remarkable abilities can not help axolotls when they are cooked into a burrito or devoured whole by a carp, but their unusual healing has brought them to the attention of biologists and medical scientists (as has their longevity in comparison with similar salamanders).

Axolotls are available in assorted colors.

Axolotls have joined fruit flies, mice, zebrafish, and rhesus monkeys as a model animal for the laboratory.  The salamanders may individually be vivisected, dissected, and subjected to crazy organ transplants or chemical manipulations, but overall they have found an ecosystem to thrive in. Their population numbers have been growing and axolotls will not be extinct until life science is.   Indeed if the field of regenerative medicine begins to flourish, all of humankind might have reason to revere the axolotl far more than the Aztecs esteemed Xolotl.

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