Layman's guide to synapses

Synaptic genes and gene functions can be very similar in humans, higher and lower animals

To advance general insights into synapses, work on simple model organisms can be an efficient alternative to studies in higher organisms, which are often more time consuming and expensive. Studies in simple model organisms are scientifically exciting in their own right. But they can also help to advance work in higher organisms, since developmental and functional mechanisms of synapses are often related between different organisms. Therefore, insights in one organism might help to understand similar mechanism in the other. For example, a mutation which causes uncontrolled walking behaviour in a fruitfly (Drosophila) might be associated with a gene that is closely related to a human gene. Respective mutations in this human gene are not unlikely to cause neurological conditions like mental retardation or epilepsy. Any insight gained in the simple fly model could guide and facilitate the respective neurolocial research.

Organisms as different as flies (red) and humans (blue), contain many similar genes which give rise to comparable functional or structural components of synapses. This similarity is called HOMOLOGY. It becomes apparent when analysing the genetic code, i.e. the nucleotide sequence of both genes. Alignment of these sequences often reveals enormous degrees of code identity (bottom: indicated in orange). Due to redundancy of the genetic code the proteins are generally even more similar than their DNA code. In several cases it has been shown that homology is even true at the functional level: Flies carrying mutations in certain genes were partly cured if the homologous human gene was stably inserted into their chromosomes.

Many different model organisms are being used to study synapses. Any of these organisms has specific experimental advantages and dis-advantages. Depending on the questions that are to be addressed, researchers choose the most suitable model organism. Based on the high degree of similarity, new insights obtained in any model organism are likely to have implications beyond species borders, improving the general view of synapse formation and function.


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