Bacteria can regulate the sex of the host

Some bacteria can adjust the proportion of females and males in some insects. Uppsala University researchers charted the entire genome of the bacterium that infects a close relative of the fruit fly.

The study, published in PNAS, reveals a very high exchange frequency in this group of bacteria. In the future, it is hoped that it will be possible to use these sex-adjusting bacteria as an environmentally friendly tool to combat harmful insects.

Bacteria belonging to Wolbachia group adapt to invertebrates such as insects, spiders, scorpions and worms. The bacteria spread through female eggs from one generation to the next and regulate the sex ratio in infected animals, from which many females are born. Mechanically speaking, the bacteria convert the male gene to the female, or kill the male embryo, or cause the females to produce eggs that are not fertile. However, it is common for males to not reproduce with uninfected females. This gives infected children a big advantage, and thus spreads rapidly.

Genetic studies show that these bacteria carry genes commonly found in higher organisms, but are rare in other bacteria. Scientists believe that the bacterium has "stolen" those genes from the host cell's genome and used those genes to regulate the sex ratio in insects.

In the egg of a parasitic wasp, Trichogramma kaykai, is Wolbachia. This bacterium accumulates at the end of the egg, which will develop into a reproductive organ. Wolbachia causes bee eggs to develop into female bees that are unable to breed. (Photos: Merijn Salverda and Richard Stouthamer)

Lisa Klasson, one of the authors of the study, said: 'With the help of viruses, bacteria exchange genes with each other, leading to the prevalence of genes that play an important role in regulating sex.' .

The researchers showed that their genome is evolutionary mosaic, with DNA parts from bacteria that have close relatives. Each gene has its own evolutionary history and the potential for change is infinite.

Siv Andersson said: 'It's amazing that a bacterium with only 1,000 genes can control the processes and behaviors that develop in insects'.

By charting the changes of these genes over time and finding the mechanism behind sex regulation, scientists can set the stage for the discovery of new insecticides. , based on natural principles.

Refer:
Klasson et al.The mosaic genome of the Wolbachia wRi strain infecting Drosophila simulans.Proceedings of the National Academy of Sciences, 2009;DOI: 10.1073 / pnas.0810753106