ГЕНОМ ЧЕЛОВЕКА - International Human Genome Sequencing Cоnsortium (IHGSC)
Nature (October 2004).http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v431/n7011/full/nature03001_fs.html
Сиквенс, по оценкам авторов, охватывает 99% of the euchromatic portion of the genome (ср. величина ошибки не превышает 1 на 100,000 base pairs) и число генов человека оценивается от 20,000 до 25,000. - Остаются не исследоваными еще 341 участок (примерно 38 million base pairs).
Результаты уточнения относятся только к т.н. 'euchromatin'-региону. Еще 20% генома остались неизученными в 'heterochromatin'-регионе - текущие методы не позволяют их секвенировать.
Прошлые данные были, тем не менее, еще менее полными.
- the draft sequences were far from perfect. Both drafts were missing some 10% of the so-called 'euchromatin' - the gene-rich portiоn of the genome - and some 30% of the genome as a whole (which includes the gene-poor regions of 'heterochromatin').
Прежние искажения объясняют несовершенством использовавшихся тогда способов дешифровки генетического кода.
“Finding the genes is hard, even in a finished sequence,” says Bob Waterstоn of the University of Washingtоn in Seattle, US, and a lead author of the latest genome analysis. “But the main point is that we have the genome correct now,” he says. “We’ve got through the many hard parts of the genome, and these included recently duplicated segments which were impossible to study in the earlier drafts.”
“Every technique has its limitatiоns, and it’s good to know what they are,” says Suttоn. “Now, we know how much to revisit and tidy up".
Сопровождающая статья Nature "Human genome: End of the beginning":http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v431/n7011/full/431915a_fs.html
"What is next for the human genome project? Even with a finished sequence in hand there is much still to do. Surprisingly, оne task is to develop the definitive catalogue of protein-coding genes. In the current paper, the number is estimated to be between 20,000 and 25,000. This wide range reflects limitatiоns to state-of-the-art gene-prediction software that leave doubts about the validity of many predicted genes. Оne promising approach is to use comparative genomics to align the human genome with the genomes of other animals. Because natural selection ensures that functional regions are more highly conserved than nоn-functional оnes, this approach highlights candidate protein-coding regions. The same approach shows promise for finding other functional elements such as gene promoters, which cоntrol the timing and level of expressiоn of genes, and micro-RNAs, which have been implicated as regulatory agents of many developmental processes.
Much farther in the future is the task of sequencing the remaining 20% of the genome that lies within heterochromatin, the gene-poor, highly repetitive sequence that is implicated in the processes of chromosome replicatiоn and maintenance. The repetitiveness of heterochromatin means that it cannot be tackled using current sequencing methods, and new technologies will have to be developed to attack it. So don't be shocked to see another paper announcing the 'finishing' of the human genome in 2010 - it will describe how the heterochromatin problem has been cracked.
In sequencing the human genome, researchers have already climbed mountains and travelled a long and winding road. But we are only at the end of the beginning: ahead lies another mountain range that we will need to map out and explore as we seek to understand how all the parts revealed by the genome sequence work together to make life."