BACKGROUND: For the first time ever, scientists have successfully sequenced the entire genomic structures of two dog breeds: the boxer and the poodle. This is a major step forward for research in such fields as veterinary medicine. Extending this work to the human genome could help doctors better understand and fight human diseases and illnesses, including cancer research.
THE STUDY: In a new study, scientists at the Institute for Genomic Research found distinct genetic differences between boxer and poodle dog breeds, and went on to compare those variations in the genomes from nine other breeds, as well as the genomes from four types of wolves and a coyote. They did this by tracking short stretches of DNA that occur randomly, called short interspersed elements (SINEs), which often turn the expression of those genes up, down or even off. Ultimately they found that the overall dog population contains at least 20,000 differences.
THE IMPLICATIONS: For genomics researchers, variable SINEs can act as signposts for specific genes linked to a disease or traits. Identifying those genes is easier to do in dogs because they have been selectively bred for so long, creating the highest degree of physical and behavioral differences seen within a species. A dog genome is estimated to include 19,300 genes, and nearly all of them correspond to similar human genes. Specific breeds are predisposed, for instance, to heart disease, cancer, blindness, deafness, and other common disorders. A second study documented many of those disease-related differences.
HOW GENES WORK: Everyone has a set of chromosomes, each containing two halves, one from each parent, and each containing a complete set of gene, so that each chromosome has two copies of every gene. The "dominant" gene is the one that is expressed, such as for brown eyes. A "recessive" gene produces a particular trait -- for instance, for blue eyes -- only if its effects are not over-ridden by those of a dominant gene. Genes are normally transmitted unchanged from one generation to the next, but sometimes a mutation occurs: the structure of the gene is changed. Genetic engineers study these mutations in hopes that it may one day be possible to correct errors in genetic coding that are responsible for specific diseases or disorders.
The Biophysical Society contributed to the information contained in the TV portion of this report.