A telomere is the end region of a chromosome that helps protect it from shortening during DNA replication, and has a repetitive and characteristic DNA sequence. A recent paper looks at the role of a protein called Rap1 in both telomere function and transcriptional regulation. Rap1 is important to prevent telomere recombination (exchange of segments of DNA) and fragility, which can lead to events characteristic of cancer in mammals. Images above show chromosomes from mouse cells without Rap1. The telomere signal on each chromosome strand is labeled with one color, and telomere recombination can be seen when the signals are exchanged (arrows).
Reference: Paula Martinez, Maria Thanasoula, Ana R. Carlos, Gonzalo Gómez-López, Agueda M. Tejera, Stefan Schoeftner, Orlando Dominguez, David G. Pisano, Madalena Tarsounas and Maria A. Blasco. Reprinted by permission from Macmillan Publishers Ltd: Nature Cell Biology 12, 768–780, copyright 2010. Paper can be found here.