A tale of enzymes and sun

By Martín Bonfil Olivera

Published in Milenio Diario, august 4, 2010

Sometimes, evolution plays dirty.

Once upon a time there was a planet (ours) where, about 3.5 billion years ago, life emerged. But the first cells confronted a problem: their star emitted, apart from visible light, a respectable amount of ultraviolet rays. And this high energy radiation normally damages complex molecules, like the nucleic acids that store the genetic information. The result: mutations and death. Life was tough in those days.

In the course of evolution, millions of years later, photosynthetic organisms that released oxygen (O₂) emerged. About 2.4 billion years ago, the Earth's atmosphere was became full of this gas. Part of the oxygen, high in the atmosphere, reacted to form the famous ozone layer (O₃), that protects us today – although not fully– from the excess of ultraviolet radiation.

But evolution could not wait for an ozone layer. Way before that, some adaptations emerged to repair the damages that ultraviolet light caused in the cell's DNA. One of the most efficient ones was the enzyme photolyase: a protein that, activated by the visible light from the sun (hence the suffix,"photo"), reverts the damage in DNA (specifically, it breaks thymine dimers: abnormal bonds between two "steps" of of the spiral ladder of the double helix, so that when genetic information is copied into the next cellular generation, it causes mistakes: mutations).

Photolyase was so successful that today it is found in almost every living organisms: bacteria, fungi, plants, fish, insects and some mammals, like marsupials (such as kangaroos, which carry their immature babies in their bags). But -and here comes the cruel evolutionary prank– something happened along the way. One of the branches of the tree of life suffered a mutation that eliminated the photolyase genes. As a result, humans, and all other animals with a placenta (placentals), lack photolyase, thus making us more susceptible to skin cancer. This is why we depend on sunscreens when we go to the beach or when we walk in the street in sunny days.

Fortunately, last week, Nature magazine published the work of a Chinese researcher, Dongping Zhong, and his team, from Ohio State University, in Columbus, where they describe the detailed molecular working of the repair mechanism of photolyase from the fruit fly Drosophilia melanogaster. With this and other studies, it is possible to visualize the use of this enzyme in creams that protect us from skin cancer by repairing the damages that ultraviolet light causes in the DNA of our skin cells (it has been demonstrated that photolyase can be applied to the skin inside liposomes –fat vesicles– in in the form of cream and has protective effects).

Basic science thus gives a possible solution to an evolutionary injustice. All in the name of a good tan.

(translated by Adrián Robles Benavides)

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Scientists on television

By Martín Bonfil Olivera

Published in Milenio Diario, July 28, 2010

The other day, I was talking to a friend and mentioned something about the Big bang theory, and the inevitable reference turned up: "yo mean the TV show?".

The thing is, The big bang theory, the wonderful sitcom that debuted in 2007 and has turned into a world success, represents a conflict for people, like this columnist, who have a scientific education.

On the one side, it is really good. It has endearing characters, among which the problematic Sheldon Cooper stands out, a theoretical physicist with two PhDs, and an IQ of 187, whose total lack of social abilities, humor and modesty (there are people who think that it has a slight form of Asperger's syndrome, a type of autism) makes him unbearable, cute and very funny, all at the same time.

Together with his friends Leonard, Howard and Rajesh, Sheldon works in the prestigious CalTech (California Institute of Technology), in Pasadena, and the adventures of this quartet obsessed with science and technology –but also with comics and other elements of geek culture– make every chapter a mixture of references to scientific theories and concepts –which are surprisingly accurate: the program has good scientific advisors– combined with very funny situations. A true delight for people who, beyond comedy, can appreciate the scientific jokes and references (even George Smoot, Physics Nobel laureate in 2006, of whom we talked here last week, participated in a small sequence at the end of one of the chapters).

But, on the other hand, the sitcom presents a series of stereotypes against which the science community has fought for a long time: it shows scientists as antisocial beings, misfits, geniuses but incapable of doing the easiest tasks, obsessive, absent-minded, ultra-logic and humorless.

Actually, scientists are just human beings… although, as anybody who lives near one –physicists, in particular, or even worse, mathematicians– can testify, all these stereotypes have a certain measure of truth. Maybe that's why we scientists love The big bang theory, even though sooner or later we have to pay the price of having our friends tell us that we're just like Sheldon.

(translated by Adrián Robles Benavides)

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Math and stars

By Martín Bonfil Olivera

Published in Milenio Diario, January 20, 2010

Math has a special relation with physical reality: it allows us to describe it. This is clearly seen in astronomy: mathematical models, from Ptolemaeus, through Copernicus, up to the glorious Newtonian description and Einstein's modern vision, have allowed us to describe with ever greater precision, and to understand, with great depth, the behavior of celestial bodies. Compared to this, the foolish "predictions" of astrology look like incoherent babble.

What we still do not understand is why math is useful to describe the world. November 2009 edition of the mexican magazine Ciencia y desarrollo (Science and development), where he has written for over 30 years, José de la Herrán, a pioneer in science popularization in Mexico, describes a curious example. It is a study to verify the validity of an old astronomical mystery: the famous, Titius-Bode law.

The law, postulated by German astronomer Johann Daniel Titius in 1776 and popularized by his colleague , fellow German (and namesake!) Johann Elert Bode in 1772, asserts that the distance from the Sun to the planets of the solar system (or, to be more precise, the major semi-axes of their elliptic orbits – the major radii, but the word radius is only used for circles, not for ellipses) seems to be related with a peculiar numerical succession: 0, 3, 6, 12, 24, 48...

Initially, the "law" was not taken seriously: although it was accurate for the then-known planets (Mercury to Saturn), it predicted a non-existent planet in the fifth position, between Mars and Jupiter. But when Uranus was discovered in 1781, and it was confirmed to occupy the spot predicted by it, the law was studied again. The "lost planet" was searched for and in 1801 asteroid Ceres was found, the biggest one in the asteroid belt (today considered as a planet did not manage to form, probably due to Jupiter's great gravitational influence). In general, the law predicted, with less than 5% error, the positions of all planets.

Then, in 1846, Neptune was discovered. Its distance to the Sun did not fit with the prediction (30% error). The same thing happened with Pluto (96% error!). The prestige of this law collapsed, and it was demoted to a mere coincidence.

Here Mexican astronomer Arcadio Poveda, from the Astronomy Institute at UNAM enters the scene. In an article published in 2008 in the Revista Mexicana de Astronomía y Astrofísica (Mexican Astronomy and Astrophysics Journal, in co-authorship with Patricia Lara), he studied 55 Cancri, in the constellation of The Crab, a "nearby" star (about 12 parsecs; more than 40 light years) in whose surroundings, five more planets have been discovered between 1996 and 2007. He found that in general, their distances agree with Titius-Bode law, if it is assumed that there's a missing planet between the fourth and the fifth ones (maybe this would reveal that the gravitational dynamics of emerging planetary systems prevents the formation in certain orbits). Poveda even predicts the position of two planets surrounding 55 Cancri; lets see if these are found.

Although it has been criticised, Poveda's work is very suggestive. The Titius-Bode law is still an enigma: if it were valid, although we still don't know why (epistemologists would say that it is a phenomenological law that lacks its proper theoretical explanation), it could help discover new planets in other planetary systems.

(translated by Adrián Robles Benavides)

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Freedom and limits

By Martín Bonfil Olivera

Published in Milenio Diario, January 13, 2010

Maybe gay marriages are, as stated by that arbiter of morals, catholic bishop Onésimo Cepeda, "a stupidity" (Milenio Diario, December 23). But if it is so, it's a stupidity homosexuals, as any other citizen, have a right to commit.

And maybe, as stated by journalist Carlos Marín (Milenio Diario, January 8), this guy Esteban Arce "has the right to express his homophobia"… but to do so in public, as main host to a popular TV show and "leader of opinion" (this shows the current sad cultural level of the average Mexican TV watcher) is wrong, because it violates other people's rights.

Yes, free speech (from which free press is derived) is vital in every true democracy. But it's not more important than other rights. It has, necessarily, limits: teaching people how to commit suicide or to make Molotov bombs, or to promote the use of drugs, violence, killing black people… or to discriminate is not allowed. If a TV host's expressed the opinion that blacks or indians are inferior, he or she would commit the same mistake and would deserve to be criticized. First of all, because it's false, but also because it's discriminatory.

Esteban Arce misinforms his audience: he expresses as true opinions contrary to current scientific knowledge, which shows that homosexual behavior is natural (it is clearly shown by Luis González de Alba in his column from last Sunday; Milenio Diario, January 10), and "normal", in the sense that it is not "sick", and that children raised by same-sex couples are also normal (i.e. not. "sick").

Why should we prefer criteria based on scientific knowledge to criteria based on religious dogma? Among other things, because they are verifiable, and have been verified: they work. Besides, they can be corrected if errors are found, in sharp contrast to the church's "truths". That's why the Mexican Constitution (third article) makes it mandatory that education be based "in the results of scientific progress", and demands that teaching be kept "completely separated from any religious doctrine".

What is sought is not to give "privileges" to certain minorities, but to guarantee that all and every citizen has the same rights. And for good reasons. The church can tear its garments on it, but religious freedom also has its limits (also, for good reasons, in this case historical ones): it cannot interfere in politics, since the Constitution prohibits it (article 130). The government obligation is to secure the rights of everyone, and to maintain the required separation of church and state. People will need to keep a watchful eye to make sure this happens.

(translated by Adrián Robles Benavides)

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Against scientific illiteracy

By Martín Bonfil Olivera

Published in Milenio Diario, January 6, 2010

Every time that I go out on vacations I take with me something good to read. This year's end was no exception: I chose the most recent work of my friend Marcelino Cereijido, Mexican-argentine researcher at Cinvestav: Science as calamity, an assay about science illiteracy and its effects (Gedisa, 2009).

This is not the first time I enjoy his excellent prose and even better ideas. Several trips to the beach have been made more enjoyable thanks to other little jewels from him: Brainless science, double craziness (Siglo XXI, 1994, where he advices a young person about the challenges, difficulties and disappointments that awaits her if he or she decides to be a scientist in a third world country), Why we don't have science, (Siglo XXI, 1997, where he presents the well-sustained hypothesis that the culture of Latin-American countries, with their Hispanic-Portuguese catholic influence, is one of the fundamental causes that our countries do not understand, support, nor, most importantly, develop or take advantage of modern science), and Houssay's nape (Fondo de Cultura Económica, 1990, an intimate and penetrating autobiographic account that tells his experience when becoming a scientist –he even studied with Nobel awarded professors– to later be persecuted, imprisoned and exiled by the catholic obscurantism of the Argentine military dictatorship.

The book can, in my opinion, be divided in two sections. The first presents a view of science, its history and the current situation of scientific illiteracy. The second part –which I considered more convincing and stimulating- raises the grave problem that such illiteracy imposes the third world, placing it at disadvantage in front of the first world, and dares to make some proposal outlines for its solution.

Cereijido states that scientific illiteracy in non-developed countries consists not only in not having science of their own, but in lacking a culture that would allow them to even realize this, and to value the heavy problem of this lack. But the really alarming thing is to realize, as demonstrated in the book, that there has always been a strategy of the first world to guarantee that the third world keeps being underdeveloped. This asymmetry is what today is really threatening global equilibrium, so drastic measures need to be taken to fight it… Only we'll have to do it ourselves. This is the base for his stimulating proposals. Now the task will be to spread them, discuss them and put them in practice… Count me in.

One complaint, though: the book, unfortunately, like many books from Ibero-American editorials, is very badly edited. Commas before verbs, or incorrectly added into phrases, which change their meaning; numerous references that do not appear in the bibliography, repetitions and, even, some sloppyness in the way the text is organized; not author's mistakes, but the editor's, from whom we would expect a more profound and professional work (because is the editorial house's, not the author's, responsibility to take care of all the details, editorial as well as the coherence and clarity of the text).

Summarizing: an enjoyable and intelligent book, but also an important and timely one. Even urgent. I hope every person that has to do with science in Latin American countries (researchers, students, government people, politics… citizens!) reads it.

(translated by Adrián Robles Benavides)

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