A virus that disrupts the sexual routines of roundworms

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Credit: Wageningen University

Viruses influence the sex life of the C. elegans roundworm. Male roundworms of this non-parasitic nematode species are less sexually attracted to females infected with Orsay virus. The virus also ultimately leads to more male offspring and therefore to an increase in mating behavior. This has been demonstrated in the doctoral research of microbiologist Lisa van Sluijs, a lecturer at the Nematology Laboratory at Wageningen University and Research (WUR). The lessons of this research are also interesting for the future protection of plants against parasitic nematodes.

The success of sexual reproduction depends on many aspects such as physical attraction, choice of mate and environmental factors. The presence of pathogens can influence reproductive success, but it was not known how this worked until now.

For her research, Lisa van Sluijs looked at the influence of the Orsay virus on Caenorhabditis elegans. It is a free (i.e. non-parasitic) roundworm (nematode) about 1 mm long that lives in the soil and is widely used for basic research.

The Orsay virus is believed to primarily infect nematodes, according to Van Sluijs, but it belongs to the larger group of nodaviruses that can infect both mammals and insects. “Pathogens have a huge influence on the biodiversity of species. But until now, we did not know how microorganisms adapt their sexual behavior to the presence of a pathogen.”

Males recognize infected females

Van Sluijs’ research (carried out with the Nematology chair group in collaboration with the Virology chair group and funded by the Netherlands Organization for Scientific Research (NWO)) shows that a virus is capable of significantly disrupting life sex of C. elegans microscopically small. . Males have been shown to be able to remotely identify females infected with the virus in the laboratory, after which they mainly focused on females not infected with the virus.






Two reproductive nematodes, accelerated sixteen times. Credit: Wageningen University

Increased mating activity

During the experiment, Van Sluijs and his colleagues also eventually observed more male offspring, indicating increased mating activity between nematodes, in a species dominated by hermaphrodite females that produce both ova and sperm. Males are only “born” after a female has mated with a male. Females seem to prefer to reproduce by self-fertilization rather than by mating with a male, but only deviate from it if they are not, or no longer, capable of producing sperm on their own.

“This is one of the reasons why males are so rare, females are overwhelmingly dominant in the population and the population shows relatively little genetic variation,” says Van Sluijs.

More male offspring

However, during her research, she discovered that the presence of the virus ultimately increased the number of males in the population. Van Sluijs says that “healthy females produce more offspring, and after mating with a male, half of that offspring will be male. If a large number of females are infected, then they will produce few female offspring, while that healthy females will mate more frequently with males, producing large numbers of both female and male offspring. And because males are less susceptible to the virus, pathogenic pressure on the population may begin to decrease again after a time.

Protect crops against parasitic nematodes

In organisms that can reproduce both by self-fertilization and by mating, males are sometimes considered “superfluous”, but research shows that male roundworms do influence the reproduction and survival of the species. This mechanism can also occur in some parasitic nematodes that cause crop damage.

Van Sluijs explains that “various plants have developed weapons to protect themselves against parasitic nematodes. But an increase in the proportion of males in a nematode species like this could speed up the genetic development of these nematodes, thus contributing to a faster breakthrough when it comes to plant resistance. If we understand this process, we should be able to step in and ensure that the development and spread of these so-called pathotypic lineages is inhibited.


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More information:
Lisa Sluijs et al, Viral infection modulates male sexual behavior in Caenorhabditis elegans, Molecular ecology (2021). DOI: 10.1111 / mec.16179

Provided by Wageningen University


Quote: A virus that disrupts the sexual routines of roundworms (2021, October 18) retrieved on October 18, 2021 from https://phys.org/news/2021-10-virus-disrupts-sex-routines-roundworms.html

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