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martes, 21 de octubre de 2008


Alteración de la cantidad de lípidos en la sangre. Existen muchos tipos. Las más frecuentes (en el mundo occidental) son las hiperlipidemies, es decir, altos niveles de lípidos circulando en la sangre.

De: Obesidad y Metabolismo: La importancia de "la opinión de tu cuerpo"


Alteració de la quantitat de lípids en la sang. N'hi ha de molts tipus. Les més freqüents (en el món occidental) són les hiperlipidèmies, és a dir, alts nivells de lípids circulant a la sang.

De: Obesitat i Metabolisme: La importància de "l'opinió del teu cos"

jueves, 14 de febrero de 2008

Genetic and Epigenetic Origins of Magic

If you take a closer look at the familiar relationships in Harry Potter books, it becomes clear that magical abilities are heritable, that means they have a genetic basis. A group of Muggle Scientists without magical abilities from the Oxford University studied the books of JK Rowling to assess the evidence for a genetic basis to magic as the seventh and final book of Harry Potter is published.

They used techniques that are normally used in genetics. To study genetics, family lineages are useful tool. There are some complete family lineages in Harry Potter books, most notably the family around Sirius Black, a family that can look at hundreds of years of „toujours pure“ magical tradition. In this family, just one case of non-transmission of magical abilities has been reported, this resulted in a squib offspring. When it has to be determined whether a disease is based on genetics or on environmental factors, very useful tools are families with twins, like the Weasley or Patil twins. Both are monozygotic and have clearly magical abilities.

Another technique that is frequently used by geneticists are adoption studies. The protagonist himself, Harry Potter, is in such case, as he was raised by the Dursley family, all of them born-and-bred muggles, after the death of his parents, great magicians James and Lily Potter. Although Harry was not aware of his magical capabilities until his 11th birthday, they did not decrease in the muggle environment. However, they are likely to be affected by factors such as experience and emotional state.

Of all the magical abilities described in Harry Potter books, three of them seem to be linked to specific genes and furthermore directly inherited to the offspring. The ability of speaking to snakes (also known as the parseltongue), is known to be a feature of only direct descendants of Salazar Slytherin. Furthermore, Sybill Trelawney, a professor of divination at Hogwarts school, is a seer and so was her great great grandmother. Lastly, Nymphadora Tonks, a character in the fifth Harry Potter book The Order of the Phoenix, was able to change her physical appearance (a metamorphmagus) and so was her son.

The authors hypothesize an epigenetic mechanism. Epigenetics refers to chromatin and DNA modifications that change the expression of genes, but do not involve changes in DNA sequence. The regulation of gene expression is mediated through the accessibility of the Transcription machinery to DNA. The hypothesis is that a profound mutation in an evolutionary ancestor occurred in a histone gene, which radically altered genome wide chromatin structure. Histones are the main protein components of chromatin, the complex that constitutes chromosomes. This created new sites of chromatin accessibility and altered gene regulation, including novel “magical enhancer” elements to drive expression of genes (figure 1) related to magic.

In genetics, an enhancer is a short region of DNA that can be bound a set of transcription factors to enhance transcription levels of genes. A dominant mutation in the histone gene could provide heritability of this epigenetic effect. Such a mechanism originating in our ancestors supports the fact that there are non-human creatures with magical abilities, like for example, house elves, goblins or the centaur. This study clearly shows that some aspects of magic have a genetic basis and that this is rather related to a magical enhancer element than to single gene effects.

This post is a contribution of Max Becker. Catalan and Spanish versions are also available.

domingo, 13 de enero de 2008


Els al·lels són les variants que pot presentar un gen

De Educació de l'atzar, educació a l'atzar


Los alelos son las variantes que puede presentar un gen.

De LA educación del azar, la eduacación al azar

Deriva genètica

l'atzar és el component principal de processos genètics com la pèrdua d'al·lels poc freqüents, el que es coneix com deriva genètica. Els al·lels són les variants que pot presentar un gen. Si una variant és poc freqüent en una població, per atzar pot que no passi a cap dels fills d'aquesta població. L'atzar haurà fet desaparèixer l'al·lel.
De Educació de l'atzar, eduació a l'atzar

Deriva genética

El azar es el componente principal de procesos genéticos como la pérdida de alelos poco frecuentes, lo que se conoce como deriva genética. Los alelos son las variantes que puede presentar un gen. Si una variante es poco frecuente en una población, por azar puede que no pase a ninguno de los hijos de esta población. El azar habrá hecho desaparecer el alelo.

De Educación del azar, educación al azar