CRISPR technique reveals genes that regulate physiological, behavioral changes

In a social hierarchy, rank is a condition that is not exclusively claimed by human beings. In the animal world, male peacocks have vividly colored plumes to show dominance, while underwater, male fish exhibit an array of vivid colors to do the same.

Beau Alward, assistant professor of psychology at the University of Houston with a joint appointment in biology and biochemistry, used the Nobel Prize winning method of gene editing to discover that two paralogous androgen receptor genes control social status in African cichlid fish. Image Credit: University of Houston.

In spite of the associations identified between behavior, social status, and physiology, the molecular foundation of social status has remained a mystery, until now.

We discovered that two paralogous androgen receptor genes control social status in African cichlid fish.”

Beau Alward, Assistant Professor of Psychology, University of Houston

Alward, who also has a joint appointment in biology and biochemistry, has reported the results of the study in the Proceedings of the National Academy of Sciences.

Paralogs are essentially duplicate genes; and androgens are hormones, such as testosterone, that are important for sexual development in males.

Testosterone binds to androgen receptors to exert its effects. What we found through genome editing is that the two genes encoding these receptors are required for different aspects of social status. This type of coordination of social status may be fundamental across species that rely on social information to optimally guide physiology and behavior.”

Beau Alward, Assistant Professor of Psychology, University of Houston

Alward employed CRISPR/Cas9 gene editing, often known as “genetic scissors,” to make these findings. The developers of the CRISPR technique recently received the Nobel Prize in Chemistry for their breakthrough invention. The CRISPR method enabled Alward to verify factors that control behavioral and physiological changes.

He also discovered that AR alpha (ARα) and AR beta (ARβ)—two androgen-receptor (AR) paralogs found in cichlid fish—control the traits that establish their mating opportunities and survival.

We’ve shown that ARβ controls coloration, a super key function because females prefer to mate with those that are brightly colored, and that ARα controls behavior, which can change rapidly due to social cues and also determines mating success.”

Beau Alward, Assistant Professor of Psychology, University of Houston

Such independent control of behavior and color changes by the pair of receptors indicates that separate mechanisms exist in the brain, and that enables Alward and his group to analyze them in isolation.

“The fact that these are independent implies that this is how flexible social status could be regulated by similar independent mechanisms in other species, including humans,” Alward concluded.