4 ms·

From a bit ago... "but why does it infect humans?" https://www.sciencedaily.com/releases/2016/02/160209090622.htm https://www.sciencedaily.com/releases/2016/02

by shagie 2y ago

From a bit ago... "but why does it infect humans?" https://www.sciencedaily.com/releases/2016/02/160209090622.htm https://www.sciencedaily.com/releases/2016/02/160209090622.h... Toxoplasmosis: Morbid attraction to leopards in parasitized chimpanzees > Researchers have shown that chimpanzees infected with toxoplasmosis are attracted by the urine of their natural predators, leopards, but not by urine from other large felines. The study suggests that parasite manipulation by Toxoplasma gondii is specific to each host. It fuels an ongoing debate on the origin of behavioral modifications observed in humans infected with toxoplasmosis: they probably go back to a time when our ancestors were still preyed upon by large felines.

dTal 2y ago
Why do they say it's "specific to each host" and not some ultra-simple algorithm like "flip the sign on $PREDATOR_FEAR_COEFFICIENT"? One might suppose that "fear of predators" is a highly conserved, re-used mechanism across a wide variety of organisms that specialize it to different predators as an "implementation detail", and toxoplasmosis attacks some feature common to everything rather than having a huge database of different creatures and their predators. Perhaps that is what they mean, but it's an odd way to put it.
- shagie 2y ago
  > The primary mechanisms of T. gondii–induced behavioral changes in rodents occur through epigenetic remodeling in neurons that govern the relevant behaviors (e.g. hypomethylation of arginine vasopressin-related genes in the medial amygdala, which greatly decrease predator aversion). And https://en.wikipedia.org/wiki/Toxoplasma_gondii#Behavioral_differences_of_infected_hosts https://en.wikipedia.org/wiki/Toxoplasma_gondii#Behavioral_d... It's got a whole list of different things that it does. Yes, some of that could be "epigenetic tweaking a gene that looks like this" would have different effects in different species (and even different genotypes - different effects for men and women). Changing the epigenetic of the regulatory genes can do different things in different species where the regulation genes have taken on different functions. Masterpiece of epigenetic engineering – how Toxoplasma gondii reprogrammes host brains to change fear to sexual attraction - https://onlinelibrary.wiley.com/doi/10.1111/mec.13006 https://onlinelibrary.wiley.com/doi/10.1111/mec.13006

by shagie 2y ago

dTal 2y ago

Why do they say it's "specific to each host" and not some ultra-simple algorithm like "flip the sign on $PREDATOR_FEAR_COEFFICIENT"? One might suppose that "fear of predators" is a highly conserved, re-used mechanism across a wide variety of organisms that specialize it to different predators as an "implementation detail", and toxoplasmosis attacks some feature common to everything rather than having a huge database of different creatures and their predators. Perhaps that is what they mean, but it's an odd way to put it.

shagie 2y ago
> The primary mechanisms of T. gondii–induced behavioral changes in rodents occur through epigenetic remodeling in neurons that govern the relevant behaviors (e.g. hypomethylation of arginine vasopressin-related genes in the medial amygdala, which greatly decrease predator aversion). And https://en.wikipedia.org/wiki/Toxoplasma_gondii#Behavioral_differences_of_infected_hosts https://en.wikipedia.org/wiki/Toxoplasma_gondii#Behavioral_d... It's got a whole list of different things that it does. Yes, some of that could be "epigenetic tweaking a gene that looks like this" would have different effects in different species (and even different genotypes - different effects for men and women). Changing the epigenetic of the regulatory genes can do different things in different species where the regulation genes have taken on different functions. Masterpiece of epigenetic engineering – how Toxoplasma gondii reprogrammes host brains to change fear to sexual attraction - https://onlinelibrary.wiley.com/doi/10.1111/mec.13006 https://onlinelibrary.wiley.com/doi/10.1111/mec.13006