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‘Glofishes’, genetically-engineered fishes capable of producing light, have escaped captive areas in southeast Brazil and are reproducing in nature, a Brazilian study has reported.
A glow fish is a genetically-engineered zebrafish that has genes for producing light. As these fishes glow in the dark, they are special for aquariums that want to attract fish. They are popular in the commercial fish market and trademarked as “Glofish”.
GloFish came into existence in the late 1990s. Scientists in Singapore designed these fishes to detect pollution in water. For the experiment, they chose zebrafishes as they can withstand various water conditions and temperature fluctuations. They are also the most common research models for various scientific studies, especially for drug development and biology.
The scientists extracted red luminescence (light-producing) genes from corals and blue and green luminescence genes from jellyfish and injected them into the developing eggs of zebrafish. They named these genetically-modified zebrafish (Danio rerio), Glofish. The fish is the size and length of standard AA batteries.
Recently, glofishes have been found in the Atlantic Forest Creeks, escaping their captivity and carrying their genetically engineered genes. The Atlantic Forest is one of the most biodiverse areas on Earth, providing shelter to a thousand species.
“They are in the first stages of invasion with potential to keep going,” said André Magalhães, study author and postdoctoral intern at Federal University of São João, Brazil. The escape of these fishes in the nearby regions of the Atlantic Forest is a matter of concern among scientists because if these fishes flourish, they can disrupt the balanced ecosystems nearby.
At this point, the adverse effects of escape are unknown. Therefore, Dr. Magalhães and his team investigated the outcomes of escape. They surveyed five headwater creeks (river networks) flowing through the forest and found transgenic fishes in all. The scientists followed up collecting these fishes every two months, counted their eggs and identified their stomach foods to determine their thriving ability.
They discovered a variety of native species such as flies, algae, water bugs into their stomach. Moreover, transgenic fishes competed with native fishes for nutrition by eating insects and other aquatic animals making the native ones deprived of food.
“The presence of aquatic macro and micro invertebrates in the stomachs of transgenic zebrafish is worrying because it shows direct uptake of native invertebrate populations which can potentially threaten creeks”, Dr Magalhães told Forbes.
Also, some escaped transgenic zebrafishes were found to be reproducing in nature. They showed a peak in reproduction during the rainy season that indicated the most favorable period for breeding.
“I found two introduced populations of transgenic zebrafish in streams here in southeastern Brazil: transgenic zebrafish adults were found in breeding conditions during almost all sampling periods (they reproduce every month of the year)”, said Dr Magalhães.
As the increase in the transgenic zebrafish population can be a threat to the ecosystem, Dr Magalhães and his team suggest some ways to control it, such as using a screen on water outlets to prevent escape, inhibiting the use of unapproved genetically modified in aquaculture, and creating awareness about transgenic organisms among fish cultivators.
The detailed study has been published in the journal Studies on Neotropical Fauna and Environment.
Contributed by: Simran Dolwani
