A ‘toxin mantle’ as defensive barrier in a tropical bird: evolutionary exploitation of the basic permeability barrier forming organelles

Abstract

Birds in the genus Pitohui and Ifrita carry potent neurotoxins that are most abundant in skin and feathers. It was unknown precisely how or where in the skin these chemicals are stored. Here, we report high‐resolution electron microscopy using OsO4 staining to visualize the location of alkaloids. Our images suggest that toxic alkaloids accumulate in multigranular bodies of epidermal cells and are likely secreted as part of the avian epidermal barrier, where they are made available for chemical defense.

Early Dengue Virus Infection in Human Skin: A Cycle of Inflammation and Infectivity

“…Birds in the wild also have many unexpected features. An interesting recent example identified that birds in the Pitohui and Ifrita genus possess the ability to carry neurotoxins in their skin and feathers (Menon and Dumbacher, 2014). These birds accumulate the neurotoxin in their skin and feathers by ingesting neurotoxin-containing insects, similar to poison dart frogs.…”

Sodium channel toxin-resistance mutations do not govern batrachotoxin (BTX) autoresistance in poison birds and frogs

“…Pitohui is one of only a few bird genera known to carry BTX (3,4,32) and has BTX levels in its skeletal and cardiac muscles that should alter NaV function (8). To investigate possible mechanisms of BTX resistance, we used a Pitohui genomic DNA library to identify and assemble genes for two Pitohui uropygialis meridionalis NaVs, skeletal muscle Pum NaV1.4 ( Fig.…”

Deadly hairs, lethal feathers – convergent evolution of poisonous integument in mammals and birds

“…Taken together, the recent work by Menon and Dumbacher and Kingdon and Agwanda underscores the fact that skin and its various appendages in both birds and mammals can become efficient and often deadly defence tools. Moreover, it highlights that poisonousness is a common convergent evolutionary strategy that has become embedded into the complexity of vertebrate skin phenotypes.…”

“…Indeed, hairs in many mammalian species have complex shapes. On a cross‐section, hairs look like a knife blade in platypus, like a dog bone in alpine pika and like a cloud bubble in Linnaeus's two‐toed sloth (Fig. ).…”

“…While the mechanisms of bird toxicity remain obscure, in a recently published issue of the journal, Menon and Dumbacher explore an intriguing idea that to achieve efficient storage of batrachotoxins in their skin and feathers, Pitohui exploit the basic permeability barrier function of their epidermis.…”