TRANSPARENT ZEBRA FISH: AID SCIENTISTS IN AUTISM BREAKTHROUGH

BY GRACE HUNNINGS: Found swimming through the tropical freshwaters of Northern India, Pakistan, Bhutan, and Nepal, zebrafish have been acknowledged for their regenerative abilities and rapid development. This species is known as being a valuable model primarily for genetic and developmental studies, along with for human disease. Extraordinarily, this fish species is completely transparent until its second week of life, where it will develop stripes as it matures into adulthood. A simple break of daylight triggers mating in zebrafish, which will allow this species to produce hundreds of transparent embryos in weekly intervals. Growing at an incredible speed, all major organs begin forming within the first 36 hours of fertilization. With this, it can be said that this species provides a continuous supply of fresh embryos to study. Using a low-power microscope, every single blood vessel can be seen within a living zebrafish embryo. Additionally, this species is low cost, prolific, and displays a vertebrate system open to genetic and chemical screening.  

In 2018, the CDC determined that 1 child out of every 59 is diagnosed with autism spectrum disorder (ASD). ASD is caused by a mutation in the SHANK3 gene, the leading ASD candidate gene. The SHANK3 gene is responsible for linking a receptor called glutamate to the receiving end of the neuronal synapse, where glutamate is necessary for establishing the learning and memory functions of the brain. ASD comes with several negative consequences, such as decreased motility in the digestive tract that causes food to move at a particularly slow pace, resulting in gastrointestinal distress (GI). Some significant indications of GI distress are severe abdominal pain, constipation, reflux, vomiting, and diarrhea. Researchers at the University of Miami have discovered clues regarding the zebrafish’s digestive tract that will one day aid people with ASD. These contributions could help alleviate GI pain, one of the most common yet unvisited and least studied symptoms in patients with ASD. Astonishingly, the zebrafish shares approximately 70 percent of its genes with humans. This association has opened the door to extensive findings and treatments that can be used to study how and why GI distress occurs.

Zebrafish have also been greatly studied to determine how this association is acknowledged in terms of GI tract motility. Associate professor of biology and leader of the University of Miami study, Julia Dallman, has focused on using zebra fish to show nervous system disorders. Her co-researchers are two graduate students, David M James and Robert A. Kozol, have been studying  how zebrafish with the mutated SHANK3 gene digest egg yolks infused with tracking beads. Using this experimental technique, they have discovered why zebrafish with mutant SHANK3 genes have less motility. The tracking beads proved that food particles would get stuck between the stomach and intestine for extensive periods of time, decreasing the production of serotonin producing cells. These findings demonstrate what may be causing such similar digestive issues and discomfort in people with ASD. This team of researchers will continue to open up the idea for potential treatments and medications that can fix the GI problem as they further their research.

This news is incredibly heartening to families affected by ASD and gives them hope. With the abundant supply of available zebrafish, and increased attention toward finding a solution to GI distress, the future looks bright for people with ASD and their families.