Fish, frogs, flies and different fauna in scientific firsts | Spectrum
Over the past century, scientists have used a variety of animal models to improve their understanding of the developing brain and autism. Here is a chronology of some of the groundbreaking discoveries with unusual models of autism.
Biologist Thomas Hunt Morgan identifies a fruit fly gene called NOTCH, which affects wing maturation and is part of a pathway that is later linked to the development of the human nervous system.
Heart to heart:
The Austrian scientist Otto Loewi observes parallel activity in two frog hearts suspended in saline solution and suspects that a chemical messenger substance he calls “vagus substance” has traveled through the solution – the first neurotransmitter identified.
The English zoologist John Gurdon replaces the core of a frog’s egg with a core from an intestinal cell. The resulting embryo successfully develops into a tadpole, showing that mature cells contain all of the information necessary to form each cell type and trigger research on induced pluripotent stem cells.
The biologist Seymour Benzer and a colleague show that mutations in a fruit fly gene called PER disrupt the fly’s circadian rhythm and present Drosophila melanogaster as a model for studying behavioral control by genes.
Scientists publish the complete wiring diagram of the Caenorhabditis elegans nervous system, paving the way for the widespread use of roundworms in studies of nervous system development.
Studies show that C. elegans is capable of habituation, a simple form of learning that can be disrupted in autism.
Milestone of the mouse:
Researchers present a single gene mouse model for autism: mice with a mutation in the NLGN3 gene.
Scientists develop one of the first invertebrate models of autism: a strain of C. elegans with a defective version of the roundworm neuroligin gene NLG1.
A zebrafish study shows that several genes in the 16p11.2 chromosomal region, which can be deleted or duplicated in autism, play a role in brain development.
Researchers report that fruit flies tend to keep a reliable distance between themselves in an enclosure, an observation that can be used to study how mutations in genes associated with autism affect social behavior.
Eight is enough:
The full genome sequence of the California two-point octopus (Octopus bimaculoides) is published, showing striking similarities with humans in genes involved in the development and function of the nervous system.
Zebrafish larvae lacking the autism-related gene CNTNAP2 are hyperactive at night, but adding estrogen-like compounds to their tank calms the fish – demonstrating the animals’ use in screening potential autism treatments.
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.
Researchers identify neurons in the forebrain of zebrafish that aid their social interactions, suggesting that zebrafish can be used to study social brain circuitry.
An analysis of 20 autism-related mutations in roundworms shows that 10 autism candidate genes are worthy of further investigation. because of their influence on the worm.
Scientists find that food moves slowly through the intestines in zebrafish larvae with SHANK3 mutations, providing an indication of the causes of digestive problems associated with autism.
The behavior of fruit flies with mutations in autism-related genes suggests that dozens of these mutations lead to habituation disorders.
Like their counterparts, zebrafish lacking the autism-related RELN gene show little interest in exposure to unfamiliar fish, which supports the use of the fish as a model for social difficulties in autism.
A study of more than 27,000 roundworms with mutations in the worm versions of 98 genes linked to autism indicates the function of these genes; many of them influence habituation.
Zebrafish larvae lacking FMR1, the gene altered in Fragile X syndrome, are hypersensitive to sound, suggesting that zebrafish can be used to study differences in sensory processing in autism.
The decrease in the expression of the autism-related gene FOXP1 in a specific region of the brain in songbirds affects the birds’ ability to memorize songs they hear from their fathers, suggesting a particular role for this gene in language learning.
Fruit flies, lacking a gene similar to the autism-related genes CHD7 and CHD8, have fragmented sleep, a problem that researchers corrected with an adapted form of “sleep restriction,” a treatment for insomnia.