Bacteria that live inside the parasitic wasps eliminate all the male wasps in the colony, and now scientists have discovered one way in which they do this.
Bacteria long ago borrowed a sex-determining gene from other insects and now use it to produce a protein that turns nearly all male eggs into females, according to a study published in the journal Cell Biology in March. Genome Biology found.
“We got really excited when we first identified this female factor in the bacterial genome because this protein explained many aspects of how the bacteria was able to ensure all the female bees,” said the study’s lead author. Amelia Lindsay“These insects are not just reptiles, but also insectivorous creatures,” an entomologist at the University of Minnesota told Live Science in an email.
Bacteria are WolbachiaThe virus lives inside insect cells and can only be transmitted directly from parent to offspring via female eggs, not sperm, so insects benefit from a predominantly female population. Wolbachia Live in insect tissues 100 years agoand discovered that it has the ability to skew sex ratios in insects. 30 years agoHowever, we are only beginning to understand how bacteria manipulate their insect hosts to facilitate infection.
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This manipulation can have dramatic consequences. For example, researchers in Samoa looked at a cluster of infected people and found that Hypolymnus bolina I found a butterfly 100 women for every 1 manIt’s all thanks to this tiny hitchhiker.
For many years, scientists Wolbachia They use various methods to increase the proportion of females in their population, including killing male fetuses and preventing the development of unfertilized eggs. Borbachia, Despite being genetically male, they develop feminine characteristics.
“Microbes have evolved incredibly complex mechanisms to manipulate their hosts.” Hiroshi AraiHe studies insect evolution at the University of Liverpool in the UK, but was not directly involved in this research.“
But one important way is Wolbachia To ensure an all-female population, host reproduction can be manipulated so that they produce only female offspring without the need for male fertilization.
The sexes of wasps have different numbers of chromosomes: males have only one set of chromosomes, so one copy of each gene, and develop from unfertilized eggs, while females have two copies of each gene and develop from fertilized eggs.
Normally, during reproduction, chromosomes are duplicated and divided into separate cells, with daughter cells retaining only half the number of chromosomes as the parent cell.. Using mechanisms that scientists don’t yet fully understand, Wolbachia Somehow they block that final step, causing females to develop from unfertilized eggs that would otherwise develop into males, so that all the wasps carry the bacteria and transmit it to their offspring.
“Wolbachia They don’t manipulate the sex determination of their host, but rather become an integral part of it.” Tobias EngleEngle, project leader for insect symbiosis at the Max Planck Institute for Chemical Biology in Germany, who was not involved in either study, told Live Science.
But how exactly? Wolbachia The forced sex determination remained a mystery.
A new study answers some of those questions.
The second study was published in the journal Neurology in June. Current Biology Discovering what’s hidden in DNA Wolbachia This gene appears to have originated from an insect rather than a bacteria, and it codes for a protein that may play an important role in sex determination.
“It’s exciting that the work of Dr. Ruan’s group and my group has converged on the same protein that causes insects to develop as females,” Lindsay told Live Science.
Both studies found that the proteins produced by two of these genes are highly similar to sex-determining genes found in other insects.
This is because the gene Wolbachia The method they use to eliminate males is one they borrowed from another insect they infected deep in their evolutionary history.
Wolbachia already It is used to reduce the number Insects that transmit diseases such as malaria, dengue fever, and Zika. And parasitic wasps, Encarsia formosa, It is used to control whiteflies, an agricultural pest. Wolbachia Controlling insect populations could further encourage the development of these projects, Arai told Live Science.
