a characteristic common to mammals?

Recent work has shown that the fur of various mammalian species glows in lovely shades of pink and red when exposed to UV light. To elucidate the cause of this unexpected phenomenon, an international collaboration involving researchers from the IPANEMA and PPSM laboratories and the company PorphyChem has identified the source of this luminescence (Luminescence is a so-called « cold » light emission, as opposed to incandescence which…). Rather than serving an ecological function, as previously assumed, the team infers that the phenomenon results from the body’s waste management of porphyrins, suggesting that this storage process is widespread in mammals. This work is published in the journal Integrative Zoology.

Nature is extremely rich in colors. Under conditions of light (Light is the set of electromagnetic waves visible to the eye…) natural, the human eye is capable of appreciating any the palette (La Palette is a café-restaurant located in the 6th arrondissement of Paris, at the crossroads…) of nature thanks to the properties ofabsorption (In optics, absorption refers to the process by which the energy of a photon is taken up…) and reflection of dyes. However, using UV light can trigger an emission that provides new visualization of some otherwise invisible dyes. In a process known as photoluminescence, certain molecules absorb UV light and re-emit light from the visible range to the near infrared (Infrared (IR) radiation is electromagnetic radiation with a wavelength…).

Photoluminescence is a well-known phenomenon in invertebrate animals; scorpions, for example, emit blue light when exposed to UV. Over the past two years, several scientists have made new observations (Observation is the action of attentive follow-up of phenomena, without the will to see them…) exciting luminescence in various mammals, such as hedgehogs, flying squirrels and even the enigmatic platypus (The Platypus (Ornithorhynchus anatinus) is a species of semi-aquatic mammal…) to beak (A beak, in the strict sense, is an external anatomical structure that allows food intake and…) of duck (Ducks are aquatic birds with characteristic beaks, domesticated or not. The…). In addition to giving rise to colorful photographs, the phenomenon has aroused the interest of the community scientific (A scientist is a person who is dedicated to the study of a science or sciences and who…) and the public. Does photoluminescence have an ecological function, as is often suggested?

An international collaboration, involving researchers from institutions in Germany, France, Switzerland, Sweden and Norway, has been working on the topic. Previous studies have observed photoluminescence in nocturnal mammals, but noted that closely related species that are active during the day are not luminescent. These studies have proposed that photoluminescence cheek (The cheek is the part of the face that covers the oral cavity, closed by the…) an ecological role, for example as a means of attracting partners and communicating with members of the same species (In the life sciences, the species (from the Latin species, « type »…)or for camouflage.

This new study rejects this hypothesis, because the conditions required to generate photoluminescence that other animals can perceive (i.e., a sufficiently intense source of UV in an otherwise dark area, as used in this work) are unlikely to occur in environment (The environment is everything that surrounds us. It is all the natural elements and…) natural.

The team sought to identify the chemical compounds generating photoluminescence by implementing the approaches ofimagery (Imagery is primarily the making and trading of physical images that…) and spectroscopy, initially designed by the IPANEMA team for the characterization of materials (A material is a material of natural or artificial origin that man shapes to…) old, to study museum specimens coupled with spectroscopy measurements available at the PPSM. Imaging allowed the team to better visualize and locate luminescent areas, while spectroscopy helped identify in situ free porphyrins as phosphors. Porphyrins serve (Servent is the contraction of the word server and client.) building blocks for several proteins vital (The Vitales are an order of dicotyledonous plants. This order has been reintroduced…) in the biology (Biology, commonly called « bio », is the science of life….) mammals, such as the hemoglobin of blood (Blood is a liquid connective tissue made up of free cell populations, including the…), and many organs readily produce them. However, overproduction of porphyrins can lead to serious skin damage, among other illnesses.

The team also observed a rapid loss of photoluminescence upon exposure to light in the laboratory. This led them to propose that mammals could remove porphyrins by using their fur as temporary storage, until the porphyrins degrade under sunlight. sun (The Sun (Sol in Latin, Helios or Ήλιος in Greek) is the star…). The observed photoluminescence would therefore be a fortuitous phenomenon with no intrinsic function, the scientists conclude.

Since the mammals studied that store porphyrins in their hair are distant relatives, the researchers deduce that this strategy (Strategy – from the Greek stratos which means « army » and ageîn which means…) storage is widespread in mammals. They therefore expect more photoluminescent mammals to be reported in the future. Furthermore, this new hypothesis helps explain why nocturnal mammals are luminescent while their diurnal relatives are not – both store porphyrins in their fur, but degradation is much faster under solar radiation (In addition to cosmic rays (animated particles of extremely high speed and energy…).

CNRS laboratories involved:
– Institute (An institute is a permanent organization created for a certain purpose. It is…) photonics for European non-destructive analysis of ancient materials (IPANEMA, CNRS / Ministry of Culture (The Culture is a pan-galactic civilization invented by Iain M. Banks through his…) /MNHN/ University (A university is an institution of higher education whose objective is the…) VSQY)
– Supramolecular and Macromolecular Photophysics and Photochemistry (PPSM, CNRS / ENS Paris-Saclay)

Reference:
Séverine LD TOUSSAINT, Jasper PONSTEIN, Mathieu THOURY, Fur (Fur is a small Danish island in the Limfjord. Fur has about 900 inhabitants. . The island…) glowing under ultraviolet (Ultraviolet (UV) radiation is electromagnetic radiation with a length…): in situ analysis of porphyrin Accumulation in the skin appendages of mammals. Integrative Zoology.

Contact:
Mathieu Thoury – European Photonic Institute for Non-Destructive Analysis of Ancient Materials (IPANEMA – CNRS/Univ Versailles St-Quentin/MNHN) – mathieu.thoury at synchrotron-soleil.fr