Fruit flies remember larval diet, influencing lifespan

Key facts

• A protein called Lsp2 carries a record of fruit flies' larval diet into adulthood.
• Fruit flies fed a low-protein diet as larvae lived longer.
• Low-protein larvae produced less Lsp2, which remained low into adulthood.
• Silencing Lsp2 in larvae resulted in longer adult lifespans.
• Lsp2 is rich in phenylalanine and tyrosine; restricting these amino acids in larval food lowered Lsp2 and extended lifespan.
• Slower protein production in young adults is linked to lifespan extension.

Scientists have discovered a mechanism by which fruit flies remember their larval diet, influencing their lifespan into adulthood. A study led by Fumiaki Obata at the RIKEN Center for Biosystems Dynamics Research identified a protein, larval serum protein 2 (Lsp2), that acts as a nutritional memory carrier.

Researchers found that fruit flies fed a low-protein diet during their larval stage lived longer as adults, though they were lighter and had reduced reproductive capacity. This lifespan extension was linked to the flies' ability to produce fewer ribosomal proteins, which are essential for building other proteins. The study suggests that this slower protein production, a consequence of the larval diet, improves proteostasis and extends life.

Experiments involving stable isotopes revealed that a significant portion of proteins in adult flies' heads were synthesized from amino acids consumed during the larval stage, indicating that this nutritional information is retained through metamorphosis. Lsp2 was identified as a key player, stockpiled by larvae and responsive to dietary protein levels. When Lsp2 levels were reduced, either through a low-protein larval diet or genetic manipulation, adult flies exhibited longer lifespans, similar to those on a restricted diet.

The research team noted that Lsp2 is particularly rich in phenylalanine and tyrosine. Restricting these amino acids in the larval diet also led to lower Lsp2 levels and increased lifespan, reinforcing the link between Lsp2 and nutritional memory. While the exact mechanism by which Lsp2 influences ribosome production remains a mystery, the study provides a concrete link between early-life nutrition and adult longevity in fruit flies.