Summary:
Dopamine is a neurotransmitter that activates different dopamine receptors throughout the central nervous system. As mostly invertebrates have been studied in the past, the researchers wanted to focus on vertebrates in this study in order to determine the evolutionary patterns of these receptors. Five dopamine receptor genes were studied in five different mammals, and it was discovered that genes that are expressed more broadly have slower evolutionary rates than genes that are expressed more narrowly. Relaxed selective constraints were found to cause these higher evolutionary rates among the receptor genes expressed more narrowly.
Data and analysis:
The researchers investigated the evolution of dopamine systems in five mammals. These …show more content…
DRD1 is the most highly expressed dopamine receptor subtype, has high levels in the mammalian forebrain, and plays a large role in many cognitive functions, while DRD2 is the second most highly expressed receptor subtype. This wider distribution of DRD1 and DRD2 in the central nervous system than the others could account for their slower evolutionary rate. This is because broadly expressed receptors likely interact with more molecules and are required to function under a variety of cellular conditions. Therefore, harmful mutations in broadly expressed receptors results in higher pleiotropic constraints, rather than in area-specific genes. In addition, by analyzing the orthologous pairs between human and mouse genes, they found that the negative correlation between broad expression and evolutionary rate was significantly larger than between expression abundance and evolutionary rate. Therefore, they concluded that it is the breadth of gene expression, not the level of expression, which has greater influence on determining rates of evolution. Since this study focused on mammalian dopamine receptor genes, they conclude that the broad expression is likely the cause of DRD1 and DRD2’s slower evolutionary
Dopamine is a neurotransmitter that activates different dopamine receptors throughout the central nervous system. As mostly invertebrates have been studied in the past, the researchers wanted to focus on vertebrates in this study in order to determine the evolutionary patterns of these receptors. Five dopamine receptor genes were studied in five different mammals, and it was discovered that genes that are expressed more broadly have slower evolutionary rates than genes that are expressed more narrowly. Relaxed selective constraints were found to cause these higher evolutionary rates among the receptor genes expressed more narrowly.
Data and analysis:
The researchers investigated the evolution of dopamine systems in five mammals. These …show more content…
DRD1 is the most highly expressed dopamine receptor subtype, has high levels in the mammalian forebrain, and plays a large role in many cognitive functions, while DRD2 is the second most highly expressed receptor subtype. This wider distribution of DRD1 and DRD2 in the central nervous system than the others could account for their slower evolutionary rate. This is because broadly expressed receptors likely interact with more molecules and are required to function under a variety of cellular conditions. Therefore, harmful mutations in broadly expressed receptors results in higher pleiotropic constraints, rather than in area-specific genes. In addition, by analyzing the orthologous pairs between human and mouse genes, they found that the negative correlation between broad expression and evolutionary rate was significantly larger than between expression abundance and evolutionary rate. Therefore, they concluded that it is the breadth of gene expression, not the level of expression, which has greater influence on determining rates of evolution. Since this study focused on mammalian dopamine receptor genes, they conclude that the broad expression is likely the cause of DRD1 and DRD2’s slower evolutionary