Drosophila fly article dating before 1950
"To our knowledge, Spaid is the first bacterial effector protein identified to date that affects host cellular machinery in a sex-specific manner," says Harumoto."And it is also, to our knowledge again, the first paper to identify an insect endosymbiont factor causing male killing.But despite several attempts, the identity of this of this male killer has remained a mystery.Now, Professor Bruno Lemaitre and Dr Toshiyuki Harumoto at EPFL have identified the elusive male-killing bacterial factor, solving the mystery. The gene for Spaid is known to encode a protein that has particular structural characteristics needed for its localization and activity inside the bacterium (ankyrin repeats and de-ubiquitinase domains).
The original idea was that Spiroplasma produces an "androcidin" toxin, which kills males.
The existence of male-killer bacteria appear at first sight puzzling, but studies have shown that it promotes the long-term persistence of the symbiotic bacteria by increasing the frequency of infected females who then transmit the bacteria to their offspring.
Male-killing is not restricted to Spiroplasma but is also observed in several other endosymbiotic bacteria.
At first, scientists thought that what lay behind this was a genetic mutation, but it was later discovered that the cause was a hidden bacterium, Spiroplasma is an endosymbiotic bacterium that lives in the fruit fly's blood and is passed on to it offspring through the female's oocytes.
This bacterium remains largely hidden from its host but induces a fascinating reproductive manipulation: the specific killing of male embryos.