A recent investigation reveals that horsehair worms exert control over their insect hosts by utilizing genes they have obtained from those very hosts. This research offers new insights into the impact of horizontal gene transfer on evolutionary processes.
Led by Tappei Mishina from the RIKEN Center for Biosystems Dynamics Research (BDR), the study uncovers how parasites can exert influence over their hosts using genes they have most likely obtained through a process known as horizontal gene transfer. The research has been formally published in the scientific journal Current Biology.
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Parasitic Manipulation and Host Behavior
Parasites often alter the behavior of their hosts to bolster their own survival and reproductive capabilities. Horsehair worms serve as an intricate example of this form of behavioral control. Originating in water, these worms use aquatic insects like mayflies to travel to dry land, where they wait to be consumed by terrestrial insects, such as crickets or mantises.
Upon entering these new hosts, the horsehair worm commences its growth and subsequently alters the host’s behavior. Once mature, the worm coerces the host into water, frequently resulting in the host’s death, thereby fulfilling the worm’s lifecycle and allowing for reproduction.
Chordodes horsehair worms utilize mantids as their final hosts. After reaching maturity within the mantids, they compel their hosts to venture into bodies of water where they can reproduce. Photo Credit: Takuya Sato
Prior research has suggested that horsehair worms influence their hosts to navigate towards light, thereby drawing them closer to water bodies. This is believed to be achieved through molecular substances that simulate those found in the hosts’ central nervous systems. However, the precise origins of these molecular imitations have remained elusive.
Gene Expression and Behavioral Control
To elucidate this, the research team analyzed the gene expression throughout the body of a Chordodes horsehair worm before, during, and after it had manipulated its mantis host. They discovered more than 3,000 hairworm genes that showed increased expression when hosts were under manipulation, and 1,500 that showed reduced expression. Conversely, gene expression in the brains of the mantises showed no alterations and remained indistinguishable from uninfected mantises. These findings suggest that horsehair worms generate their own proteins to interfere with their hosts’ nervous systems.
The team then consulted a protein database to investigate the origins of the genes that Chordodes horsehair worms use for manipulating their mantis hosts. “Remarkably, numerous horsehair worm genes vital for host manipulation displayed strong similarities to mantid genes, which implies that they were procured through horizontal gene transfer,” states Mishina. Horizontal gene transfer is a mechanism in which one organism transfers genes to another, unrelated organism without involving reproduction. This can significantly affect evolutionary trajectories by rapidly conferring new genes or functions.
Molecular Imitation and Evolutionary Adaptation
Subsequent analysis corroborated the hypothesis that the molecular mimicry observed in Chordodes horsehair worms likely originates from horizontal gene transfer from mantids. Specifically, over 1,400 Chordodes horsehair worm genes were identified as matches to those in mantids but were either absent or significantly different in horsehair worm species that do not utilize mantis hosts. The researchers conclude that this form of mimicry is probably the outcome of numerous horizontal gene-transfer events from various mantis species throughout the evolutionary history of the horsehair worms. Genes related to neuromodulation, light attraction, and circadian rhythms seem to be particularly involved in host manipulation.
Horizontal gene transfer is a crucial mechanism for bacterial evolution against antibiotics. Mishina contends that as more instances of horizontal gene transfer among multicellular organisms are discovered, we will deepen our understanding of this process and its role in evolution at large. “The numerous instances of horizontal gene transfer we have found in the horsehair worm could serve as an excellent model for future study,” remarks Mishina. “Utilizing this model, we aim to uncover the underlying mechanisms of horizontal gene transfer and thereby enrich our understanding of evolutionary adaptation.”
Reference: “Massive horizontal gene transfer and the evolution of nematomorph-driven behavioral manipulation of mantids” by Tappei Mishina et al., published on 19 October 2023 in Current Biology.
DOI: 10.1016/j.cub.2023.09.052
Frequently Asked Questions (FAQs) about horizontal gene transfer
What is the main discovery of the research led by Tappei Mishina?
The primary discovery is that horsehair worms manipulate their insect hosts using genes they have obtained from those hosts. This offers new insights into the role of horizontal gene transfer in evolution.
What organisms are primarily involved in the study?
The study focuses on horsehair worms and their insect hosts, specifically aquatic insects like mayflies and terrestrial insects such as crickets and mantises.
How do horsehair worms manipulate their hosts?
Horsehair worms manipulate their hosts by altering their behavior, compelling them to move towards water bodies. This is achieved through molecular substances that resemble those found in the hosts’ central nervous systems.
What is horizontal gene transfer, and how is it relevant to the study?
Horizontal gene transfer is a process where one organism transfers genes to another without involving reproduction. It is relevant because the researchers found that many genes the horsehair worms use to manipulate their hosts were likely acquired through this mechanism.
What are the implications of this study for understanding evolutionary adaptation?
The findings suggest that horizontal gene transfer can have significant implications for evolutionary adaptation, allowing organisms to acquire new genes or functions rapidly. It can serve as a mechanism for complex behaviors like host manipulation.
What was the methodology used for analyzing gene expression?
The research team analyzed whole-body gene expression in a Chordodes horsehair worm before, during, and after it had manipulated its mantis host. They identified genes that were either upregulated or downregulated during the manipulation.
Does the study provide insights into other areas like antibiotic resistance?
While the primary focus is on parasitic behavior and evolutionary adaptation, the study does note that understanding horizontal gene transfer can provide insights into other areas, such as how bacteria evolve to resist antibiotics.
Who are the target readers for the study, and where was it published?
The research is intended for experts and researchers in the fields of biology, parasitology, and evolution. It was published in the scientific journal Current Biology.
What are the next steps in this area of research?
The research team plans to use the horsehair worm as a model to further investigate the mechanisms underlying horizontal gene transfer and to deepen the understanding of evolutionary adaptation.
What is the DOI for the original publication?
The DOI for the original publication is 10.1016/j.cub.2023.09.052.
More about horizontal gene transfer
- Current Biology Journal
- RIKEN Center for Biosystems Dynamics Research
- Overview of Horizontal Gene Transfer
- Understanding Parasitic Behavior
- Gene Expression Analysis Techniques
- Evolutionary Adaptation and Natural Selection
- Antibiotic Resistance and Horizontal Gene Transfer
6 comments
I can’t help but think what this means for evolutionary theory. Makes Darwin look like child’s play. Evolution’s got some new tricks up its sleeve.
who needs science fiction when you have real-life research like this. Amazing how much these parasites can do by “borrowing” genes.
Its pretty intense how much we still don’t know about the animal kingdom. Just when you think you’ve got it figured, something like this comes along.
I’m no expert but the way these parasites manipulate other creatures is just fascinating. Gives a whole new meaning to survival of the fittest, doesn’t it?
Wow, this is mind-blowing stuff! So you’re saying that these worms can actually “steal” genes from their hosts? Nature is crazier than any sci-fi movie.
horizontal gene transfer is kinda scary if you ask me. What if this happens in other species? could lead to some unintended consequences for sure.