Telomerasas

Colombia Médica

Vol. 37 Nº 4, 2006 (Octubre-Diciembre)

Telomere and Telomerase: brief review of a history initiated by Hermann Müller and Barbara McClintock
LILIAN C HUAIRE. M.S C .*
SUMMARY
What is the nature of the biological clock that determines the cells aging? What is the way to explain the genesis of diseases associated in aging? The above are only some of the questions whoseanswer could be found within the modus operandi frame of the telomere-telomerase pair, which had become in objective of study for a number of science men and women since the pioneers Hermann Müller and Barbara McClintock, until the most recent Jack Szostak, Elizabeth Blackburn and Carol Greider, among others. Keywords: Biological locks; Research personnel; History. Telómeros y Telomerasa: Breverecuento de una historia iniciada por Hermann Müller y Bárbara McClintock

RESUMEN
¿Cuál es la naturaleza del reloj biológico que determina el envejecimiento de las células? ¿De qué manera se explica la génesis de las enfermedades asociadas con el envejecimiento? Las anteriores son sólo algunas de las preguntas cuya respuesta puede ser hallada en el marco del modus operandi de la duplatelómeros-telomerasa, convertida en objeto de estudio para un sinnúmero de hombres y mujeres de ciencia, desde los pioneros Hermann Müller y Bárbara McClintock hasta los más recientes Jack Szostak, Elizabeth Blackburn y Carol Greider, entre otros. Palabras clave: Relojes biológicos; Investigadores; Historia.

In 1938, when the young North American geneticist Hermann J. Müller used to work with flies of thespecies Drosophila melanogaster, exposed to X rays at the Edinburgh Animal Genetics Institute (United Kingdom), he did not foresee the implications that his findings would have in the molecular biology and genetics in the following 70 years. He had just observed that the ends of the irradiated chromosomes, different from the other genome, did not present alterations such as deletions or inversions,thanks to the presence of a protective cap that himself called «terminal gene» and afterwards «telomere», from the greek terms «telos» (end) and «meros» (part)1 . Two years after, Barbara McClintock, respected investigator from the University of Missouri (Columbia, USA), who was dedicated to the study of corn genetics (Zea mays), described how the rupture of the chromosomes resulted in adhesion andfusion of their ends, with the consequent formation of dicentric chromosomes. She demonstrated that regardless of this damage, the ends

could be restored thanks to the acquisition of new telomere. According to her conclusions, telomeres play a crucial role in the integrity of the chromosomes, since they prevent the appearance of «rupture-fusion-bridge» cycles which are catastrophic for thecellular survival2 . The term «telomere» coined by Müller had apparently a premonitory character, though everything pointed to an immediate promissory future. The predominant skepticism of that age in the genetic field made that research on the importance of the ends of the chromosomes in replication and integrity of the cell steeply stopped. It was only reinitiated 30 years after, when themechanisms subjacent to the replication of the deoxyribonucleic acid (DNA) were revealed, fact in which James Watson worked (the same that described the double helicoidal structure of the DNA). He identified the «problem of the terminal replication» consisting on the incapacity of the cells to completely replicate the linear ends of the DNA. Watson postulated that, because of the special characteristics of* Principal Professor, Escuela Ciencias de la Salud, Universidad del Rosario, Bogotá DC, Colombia. e-mail: lchuaire@urosario.edu.co Recibido para publicación agosto 28, 2005 Aceptado para publicación septiembre 8, 2006 336 © 2006 Corporación Editora Médica del Valle
Colomb Med 2006; 37: 336-339

Colombia Médica
the synthesis of the left behind chain of nucleic acid, which cause that...