Amazing stuff! These worms exhibit sexually dimorphic behavior, the males are not non-binary, but they can be rewired to flip sexual behavior! 😇
One recurrent confirmation: In the battle of the sexes, males are expendable!
"But when microscopic worms faced a threatening signal in a lab at the Weizmann Institute of Science, only the females fled right away. The males stayed put until the signal grew much stronger. Puzzled at this difference between the sexes, the scientists used it to explore one of the greatest enigmas surrounding the brain: how the structure of its neural circuits shapes behavior. ...
The transparent, one-millimeter-long worm, Caenorhabditis elegans, is uniquely suited for probing this question because it has a relatively broad repertoire of behaviors, and the wiring of its nervous system, consisting of only some 300 neurons, has been mapped for both sexes. ...
the scientists found that worms exposed to harmful chemical substances sense the danger using receptors similar to those that convey the sensation of pain in humans, and the response of these receptors to the dangerous cue is similar in worms of both sexes. The researchers also found that while the neural circuit that picks up the danger signal consists of the same neurons in females and males, the wiring of these neurons – that is, how they are connected to one another – differs in several ways between the sexes. ...
The model identified a critical difference in the wiring, which boiled down to a single connection, or synapse, between two neurons. These two neurons were connected to one another in the female, but not the male, worms. ...
In a feat of molecular engineering, [researchers] inserted the missing connection into the danger-sensing circuit of male worms, so that it would mimic that of females. As the model had predicted, the males equipped with the synthetic synapse started fleeing from the danger, just like the females. ...
The researchers believe that this may be due to the evolutionary force that Darwin termed “sexual selection”: the preservation of features that help the animal find mates at the cost of creating greater exposure to predators or other dangers – a peacock’s tail being one iconic example. ...
This is in contrast to the female, which is actually a hermaphrodite: Her reproductive organs produce both eggs and sperm, so she can be inseminated either by her own sperm or by that of a male. ...
Whereas regular males rushed directly to the females – danger be damned – the engineered males with a synthetic synapse were much more hesitant, taking ten times longer to reach potential mates. ..."
The transparent, one-millimeter-long worm, Caenorhabditis elegans, is uniquely suited for probing this question because it has a relatively broad repertoire of behaviors, and the wiring of its nervous system, consisting of only some 300 neurons, has been mapped for both sexes. ...
the scientists found that worms exposed to harmful chemical substances sense the danger using receptors similar to those that convey the sensation of pain in humans, and the response of these receptors to the dangerous cue is similar in worms of both sexes. The researchers also found that while the neural circuit that picks up the danger signal consists of the same neurons in females and males, the wiring of these neurons – that is, how they are connected to one another – differs in several ways between the sexes. ...
The model identified a critical difference in the wiring, which boiled down to a single connection, or synapse, between two neurons. These two neurons were connected to one another in the female, but not the male, worms. ...
In a feat of molecular engineering, [researchers] inserted the missing connection into the danger-sensing circuit of male worms, so that it would mimic that of females. As the model had predicted, the males equipped with the synthetic synapse started fleeing from the danger, just like the females. ...
The researchers believe that this may be due to the evolutionary force that Darwin termed “sexual selection”: the preservation of features that help the animal find mates at the cost of creating greater exposure to predators or other dangers – a peacock’s tail being one iconic example. ...
This is in contrast to the female, which is actually a hermaphrodite: Her reproductive organs produce both eggs and sperm, so she can be inseminated either by her own sperm or by that of a male. ...
Whereas regular males rushed directly to the females – danger be damned – the engineered males with a synthetic synapse were much more hesitant, taking ten times longer to reach potential mates. ..."
From the highlights and abstract:
"Highlights
• C. elegans exhibits sexually dimorphic responses to nociceptive stimuli
• Computational models show that circuit topology accounts for the dimorphic behavior
• Model-based rewiring of single neurons or synapses flips sex-specific behavior
• Rewired males are compromised in finding mates when presented with aversive cues
Summary
The effect of the detailed connectivity of a neural circuit on its function and the resulting behavior of the organism is a key question in many neural systems. Here, we study the circuit for nociception in C. elegans, which is composed of the same neurons in the two sexes that are wired differently. We show that the nociceptive sensory neurons respond similarly in the two sexes, yet the animals display sexually dimorphic behaviors to the same aversive stimuli. To uncover the role of the downstream network topology in shaping behavior, we learn and simulate network models that replicate the observed dimorphic behaviors and use them to predict simple network rewirings that would switch behavior between the sexes. We then show experimentally that these subtle synaptic rewirings indeed flip behavior. Interestingly, when presented with aversive cues, rewired males were compromised in finding mating partners, suggesting that network topologies that enable efficient avoidance of noxious cues have a reproductive “cost.” Our results present a deconstruction of the design of a neural circuit that controls sexual behavior and how to reprogram it."
Reprogramming the topology of the nociceptive circuit in C. elegans reshapes sexual behavior (open access)
Neurons (red) in the worm’s danger-sensing neural circuits. Fluorescent labeling reveals active neuronal connections (bright-green dots) that are present in females (left) but not in males
Graphical abstract
Figure 1. C. elegans exhibit sexually dimorphic behaviors in response to nociceptive stimuli
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