Microbiology

Bacteria genes offer new strategy for sterilizing mosquitoes

wolbachia bacteria
STERILITY CULPRITS Wolbachia bacteria (red) effectively sterilize a male mosquito by infecting the insect’s testes (blue), shown at 100 times magnification. Now, researchers have identified genes that may be responsible for the sterility.

A pair of bacterial genes may enable genetic engineering strategies for curbing populations of virus-transmitting mosquitoes.

Bacteria that make the insects effectively sterile have been used to reduce mosquito populations. Now, two research teams have identified genes in those bacteria that may be responsible for the sterility, the groups report online February 27 in Nature and Nature Microbiology.

“I think it’s a great advance,” says Scott O’Neill, a biologist with the Institute of Vector-Borne Disease at Monash University in Melbourne, Australia. People have been trying for years to understand how the bacteria manipulate insects, he says.

Wolbachia bacteria “sterilize” male mosquitoes through a mechanism called cytoplasmic incompatibility, which affects sperm and eggs. When an infected male breeds with an uninfected female, his modified sperm kill the eggs after fertilization. When he mates with a likewise infected female, however, her eggs remove the sperm modification and develop normally.

Researchers from Vanderbilt University in Nashville pinpointed a pair of genes, called cifA and cifB, connected to the sterility mechanism of Wolbachia. The genes are located not in the DNA of the bacterium itself, but in a virus embedded in its chromosome.

When the researchers took two genes from the Wolbachia

Microbe Transmission Tracked from Mother to Infant

There’s strong evidence that babies inherit their gut microbiomes from their mothers, but it’s been unclear if the microbiome transmission takes place in the womb, at birth, or after birth; there are likely multiple paths of transmission unfolding over time. Microbial diversity is crucial to building up many functions, including the immune system, digestion, and even combating complex diseases. Recent research has found a connection between our gut microbiomes and our mental health as well.

However, studying the direct transmission of these microbes and identifying the strains of bacteria has been difficult until recently. Now researchers at the Centre for Integrative Biology at the University of Trento (UoT), Italy, have developed methods to track this microbial “vertical transmission,” as it’s called, and made some new discoveries in their methodological study, published in mSystems, an open access journal from the American Society for Microbiology.

“We know the infant increases [its] microbial diversity after birth and will continue doing so until being an adult,” senior study author Nicola Segata, an assistant professor at UoT, tells mental_floss. “We needed to understand from where microbes are coming in the first place.”

Many microbes are likely transmitted from mother to infant at birth and just after birth through direct contact with the birth…