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Fish, frogs, flies and other fauna in scientific firsts

by  /  8 September 2021
researcher holds zebrafinch
skynesher / iStock

Over the past century, scientists have used a variety of animal models to advance their understanding of the developing brain and autism. Here’s a chronology of some of the landmark discoveries involving uncommon autism models.

 

1916

drosophilia

Notch up:

Biologist Thomas Hunt Morgan identifies a fruit fly gene called NOTCH that affects wing maturation and is part of a pathway later linked to nervous system development in people.

1920

Portrait of Otto Loewi

Heart to heart:

Austrian scientist Otto Loewi observes parallel activity in two frog hearts suspended in saline, theorizing that a chemical messenger he dubs ‘vagusstoff’ traveled through the solution — the first identified neurotransmitter.

1962

Portrait of English zoologist John Gurdon.

Pluripotent possibilities:

English zoologist John Gurdon replaces the nucleus of a frog egg with a nucleus from an intestinal cell. The resulting embryo successfully develops into a tadpole, demonstrating that mature cells contain all the information needed to create any cell type and kicking off research in induced pluripotent stem cells.

1971

Portrait of biologist Seymour Benzer

Fly time:

Biologist Seymour Benzer and a colleague demonstrate that mutations in a fruit fly gene dubbed PER disrupt the fly’s circadian rhythm, launching Drosophila melanogaster as a model for the study of how genes control behavior.

1986

Worm wiring:

Scientists publish the complete wiring diagram of the Caenorhabditis elegans nervous system, paving the way for the extensive use of roundworms in studies of nervous system development.

1990

Elegans experiment:

Studies show that C. elegans is capable of habituation, a simple form of learning that may be disrupted in autism.

2007

white lab mouse

Mouse milestone:

Researchers debut a single-gene mouse model of autism: mice with a mutation in the gene NLGN3.

2010

C. Elegans

Inching forward:

Scientists create one of the first invertebrate models of autism: a strain of C. elegans with a faulty version of the roundworm’s neuroligin gene NLG1.

2012

Zebrafish

Fish tale:

A zebrafish study shows that multiple genes in the 16p11.2 chromosomal region, which may be deleted or duplicated in autism, play roles in brain development.

2015

Fruit fly close up

Social space:

Researchers report that fruit flies in an enclosure tend to keep a reliable amount of space between them, an observation that can be used to investigate how mutations in autism-linked genes affect social behavior.

2015

Octopus bimaculoides in sand and water.

Eight is enough:

The complete genome sequence of the California two-spot octopus (Octopus bimaculoides) is published, revealing striking similarities to people in genes involved in nervous system development and function.

2016

Zebrafish

Sedated swimmers:

Zebrafish larvae lacking the autism-linked gene CNTNAP2 are hyperactive at night, but adding estrogen-like compounds to their tank calms the fish — demonstrating a use for the animals in screening potential autism treatments.

2018

Fly macro view

Two to tango:

A study of gene expression in the developing fly eye reveals the importance of interactions between genes in the 16p11.2 region during neurodevelopment.

2018

Social circuits:

Researchers identify neurons in the forebrain of zebrafish that support their social interactions, suggesting that zebrafish can be used to probe social brain circuitry.

2019

Roundworms

Picking priorities:

An analysis of 20 autism-linked mutations in roundworms flags 10 autism candidate genes as worthy of further study, because of their impact on the worm.

2019

Young zebrafish have transparent skin, which allows researchers to track the movements of glowing beads of excrement through their gut.

Gut feeling:

Scientists find that food moves through the gut slowly in zebrafish larvae with SHANK3 mutations, providing a clue to the roots of digestive problems associated with autism.

2019

Habit forming:

The behavior of fruit flies with mutations in autism-linked genes suggests that dozens of these mutations lead to impairments in habituation.

2019

Stranger danger:

Like their mouse counterparts, zebrafish lacking the autism-linked gene RELN show little interest in socializing with unfamiliar fish, supporting use of the fish as a model for social difficulties in autism.

2020

Roundworm rodeo:

A study of more than 27,000 roundworms with mutations in the worm versions of 98 autism-linked genes hints at the function of these genes; many of them affect habituation.

2020

Sound check:

Zebrafish larvae lacking FMR1, the gene altered in fragile X syndrome, are hypersensitive to sound, suggesting that zebrafish can be used to study sensory processing differences in autism.

2021

Show stopper:

Reducing the expression of the autism-linked gene FOXP1 in a particular brain region in songbirds impairs the birds’ ability to memorize songs they hear from their fathers, suggesting a specific role for this gene in language learning.

2021

Fly by night:

Fruit flies lacking a gene akin to the autism-linked genes CHD7 and CHD8 have fragmented sleep, a problem researchers corrected using an adapted form of  ‘sleep restriction,’ an insomnia treatment.

Cite this article: https://doi.org/10.53053/TIYT8223