Models for human porphyrias: Have animals in the wild been overlooked?: Some birds and mammals accumulate significant amounts of porphyrins in the body without showing the injurious symptoms observed in human porphyrias

Photoluminescence in mammal fur: 111 years of research

Photoluminescence in the pelage of mammals, a topic that has gained considerable recent research interest, was first documented in the 1700s and reported sporadically in the literature over the last century. The first detailed species accounts were of rabbits and humans, published 111 years ago in 1911. Recent studies have largely overlooked this earlier research into photoluminescent mammalian taxa and their luminophores. Here we provide a comprehensive update on existing research on photoluminescence in mammal fur, with the intention of drawing attention to earlier pioneering research in this field. We provide an overview on appropriate terminology, explain the physics of photoluminescence, and explore pigmentation and the ubiquitous photoluminescence of animal tissues, before touching on the emerging debate regarding visual function. We then provide a chronological account of research into mammalian fur photoluminescence, from the earliest discoveries and identification of luminophores to the most recent studies. While all mammal fur is likely to have a general low-level photoluminescence due to the presence of the protein keratin, fur glows luminously under ultraviolet light if it contains significant concentrations of tryptophan metabolites or porphyrins. Finally, we briefly discuss issues associated with preserved museum specimens in studies of photoluminescence. The study of mammal fur photoluminescence has a substantial history, which provides a broad foundation on which future studies can be grounded.

Fur glowing under ultraviolet: in situ analysis of porphyrin accumulation in the skin appendages of mammals

Examples of photoluminescence (PL) are being reported with increasing frequency in a wide range of organisms from diverse ecosystems. However, the chemical basis of this PL remains poorly defined, and our understanding of its potential ecological function is still superficial. Among mammals, recent analyses have identified free-base porphyrins as the compounds responsible for the reddish ultraviolet-induced photoluminescence (UV-PL) observed in the pelage of springhares and hedgehogs. However, the localization of the pigments within the hair largely remains to be determined. Here, we use photoluminescence multispectral imaging emission and excitation spectroscopy to detect, map, and characterize porphyrinic compounds in skin appendages in situ. We also document new cases of mammalian UV-PL caused by free-base porphyrins in distantly related species. Spatial distribution of the UV-PL is strongly suggestive of an endogenous origin of the porphyrinic compounds. We argue that reddish UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable. Consequently, this phenomenon may not have a specific function in intra- or interspecific communication but rather represents a byproduct of potentially widespread physiological processes.

Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry

Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation. The method is based on capillary liquid chromatography-mass spectrometry (CLC-MS), after an extraction procedure with formic acid and acetonitrile. The resulting limits of detection (LOD) and quantification (LOQ) were 0.006–0.199 and 0.021–0.665 µg mL⁻¹, respectively. This approach enabled us to quantify porphyrins in flying squirrel hairs at concentrations of 3.6–353.2 µg g⁻¹ with 86.4–98.6% extraction yields. This method provides higher simplicity, precision, selectivity, and sensitivity than other methods used to date, presenting the potential to become the standard technique for porphyrin analysis.

Evolutionary physiology at 30+: Has the promise been fulfilled?: Advances in Evolutionary Physiology: Advances in Evolutionary Physiology

Three decades ago, interactions between evolutionary biology and physiology gave rise to evolutionary physiology. This caused comparative physiologists to improve their research methods by incorporating evolutionary thinking. Simultaneously, evolutionary biologists began focusing more on physiological mechanisms that may help to explain constraints on and trade-offs during microevolutionary processes, as well as macroevolutionary patterns in physiological diversity. Here we argue that evolutionary physiology has yet to reach its full potential, and propose new avenues that may lead to unexpected advances. Viewing physiological adaptations in wild animals as potential solutions to human diseases offers enormous possibilities for biomedicine. New evidence of epigenetic modifications as mechanisms of phenotypic plasticity that regulate physiological traits may also arise in coming years, which may also represent an overlooked enhancer of adaptation via natural selection to explain physiological evolution. Synergistic interactions at these intersections and other areas will lead to a novel understanding of organismal biology.

A Draft Genome Assembly for the Eastern Fox Squirrel, Sciurus niger

The eastern fox squirrel, Sciurus niger, exhibits marked geographic variation in size and coat color, is a model organism for studies of behavior and ecology, and a potential model for investigating physiological solutions to human porphyrias. We assembled a genome using Illumina HiSeq, PacBio SMRT, and Oxford Nanopore MinION sequencing platforms. Together, the sequencing data resulted in a draft genome of 2.99 Gb, containing 32,830 scaffolds with an average size of 90.9Kb and N50 of 183.8 Kb. Genome completeness was estimated to be 93.78%. A total of 24,443 protein-encoding genes were predicted from the assembly, and 23,079 (94.42%) were annotated. Repeat elements comprised an estimated 38.49% of the genome, with the majority being LINEs (13.92%), SINEs (6.04%), and LTR elements. The topology of the species tree reconstructed using maximum likelihood phylogenetic analysis was congruent with those of previous studies. This genome assembly can prove useful for comparative studies of genome structure and function in this rapidly diversifying lineage of mammals, for studies of population genomics and adaptation, and for biomedical research. Predicted amino acid sequence alignments for genes affecting heme biosynthesis, color vision and hibernation showed point mutations and indels that may affect protein function and ecological adaptation.