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How “Chameleons” change color
Many chameleons, and panther chameleons in particular, have the remarkable ability to exhibit complex and rapid colour changes during social interactions such as male contests or courtship. It is generally interpreted that these changes are due to dispersion/aggregation of pigment-containing organelles within dermal chromatophores.
But, combining microscopy, photometric videography and photonic band-gap modelling, we show that chameleons shift colour through active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores. In addition, we show that a deeper population of iridophores with larger crystals reflects a substantial proportion of sunlight especially in the near-infrared range.
The organization of iridophores into two superposed layers constitutes an evolutionary novelty for chameleons, which allows some species to combine efficient camouflage with spectacular display, while potentially providing passive thermal protection. -src
Giffed by: rudescience From: This video
By constantly reminding the immune system what the parasite that causes leishmaniasis looks like, a persistent infection keeps the immune system on alert against new encounters, even while it carries the risk of causing disease later in life
Which is better? Long-term immunity with the cost of persistent infection OR complete riddance at the cost of becoming infected again
I think I agree that control persistent infection probably has the most robust evolutionary advantage here as if you are in an area where you are exposed to one of these pathogens it is probably best to harbor long term immunity.
It would be interesting to determine in a follow-up study if location/exposure to conspecific external pathogens increases the duration that the immune system reserves these pathogens.
“I think we need to renew our spirit of exploration. Rather than bring nature into our laboratories and interrogate it there, we need to bring our science into the majestic laboratory that is nature, and there, with our modern technological armamentarium, interrogate every new form of life we find, and any new biological attribute that we may find. We actually need to bring all of our intelligence to becoming stupid again – clueless [before] the immensity of the unknown. Because after all, science is not really about knowledge. Science is about ignorance. That’s what we do… we scientists need to teach our students to long for the endless immensity of the sea that is our ignorance. We Homo sapiens are the only species we know of that is driven to scientific inquiry. We, like all other species on this planet, are inextricably woven into the history of life on this planet.”