Publications by authors named "Ismael Galvan"

Article Synopsis
  • Sex-limited polymorphism, which is the presence of different traits in males and females, has been observed in various species, including humans, but its genetic and evolutionary mechanisms are not fully understood.
  • The common cuckoo is highlighted for its female-only color variation, where females can be either gray or rufous, influenced by negative frequency-dependent selection, which protects the rarer morph from male harassment and host species conflict.
  • Research indicates that this color variation is genetically linked to a female-restricted genome and shares ancestry with a closely related species, the oriental cuckoo, demonstrating how sex-specific traits can arise and persist across different species.
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Mechanisms occurring at the atomic level are now known to drive processes essential for life, as revealed by quantum effects on biochemical reactions. Some macroscopic characteristics of organisms may thus show an atomic imprint, which may be transferred across organisms and affect their evolution. This possibility is considered here for the first time, with the aim of elucidating the appearance of an animal innovation with an unclear evolutionary origin: migratory behaviour.

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Facultative colour change is widespread in the animal kingdom, and has been documented in many distantly related amphibians. However, experimental data testing the extent of facultative colour change, and associated physiological and morphological implications are comparatively scarce. Background matching in the face of spatial and temporal environmental variation is thought to be an important proximate function of colour change in aquatic amphibian larvae.

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Diurnal biting flies are strongly attracted to blue objects. This behaviour is widely exploited for fly control, but its functional significance is debated. It is hypothesized that blue objects resemble animal hosts; blue surfaces resemble shaded resting places; and blue attraction is a by-product of attraction to polarized light.

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An electrochemical sensor based on a screen-printed carbon electrode (SPCE) modified with porphyrin-functionalized magnetic graphene oxide (TCPP-MGO) was developed for the sensitive and selective determination of malondialdehyde (MDA), an important biomarker of oxidative damage, in serum samples. The coupling of TCPP with MGO allows the exploitation of the magnetic properties of the material for separation, preconcentration, and manipulation of analyte, which is selectively captured onto the TCPP-MGO surface. The electron-transfer capability in the SPCE was improved through derivatization of MDA with diaminonaphthalene (DAN) (MDA-DAN).

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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.

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Malignant melanoma (MM) is the most aggressive form of skin cancer, and around 30% of them may develop from pre-existing dysplastic nevi (DN). Diagnosis of DN is a relevant clinical challenge, as these are intermediate lesions between benign and malignant tumors, and, up to date, few studies have focused on their diagnosis. In this study, the accuracy of Raman spectroscopy (RS) is assessed, together with multivariate analysis (MA), to classify 44 biopsies of MM, DN and compound nevus (CN) tumors.

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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.

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Gene expression can be modulated by epigenetic modifications, which may lead to a rapid adaptation to environmental stress. After stress cessation, changes in gene expression could be reversed, which would allow organisms to maintain their phenotype under transient environments, but this mechanism is poorly understood. Social stress downregulates a gene directly involved in pheomelanin synthesis (Slc7a11) by changing DNA mC levels, avoiding cellular damage caused by stress.

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Humans accumulate porphyrins in the body mostly during the course of porphyrias, diseases caused by defects in the enzymes of the heme biosynthesis pathway and that produce acute attacks, skin lesions and liver cancer. In contrast, some wild mammals and birds are adapted to accumulate porphyrins without injurious consequences. Here we propose viewing such physiological adaptations as potential solutions to human porphyrias, and suggest certain wild animals as models.

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Parrots and allies (Order Psittaciformes) have evolved an exclusive capacity to synthesize polyene pigments called psittacofulvins at feather follicles, which allows them to produce a striking diversity of pigmentation phenotypes. Melanins are polymers constituting the most abundant pigments in animals, and the sulphurated form (pheomelanin) produces colors that are similar to those produced by psittacofulvins. However, the differential contribution of these pigments to psittaciform phenotypic diversity has not been investigated.

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Parrots and allies (Order Psittaciformes) have evolved an exclusive capacity to synthesize polyene pigments called psittacofulvins at feather follicles, which allows them to produce a striking diversity of pigmentation phenotypes. Melanins are polymers constituting the most abundant pigments in animals, and the sulphurated form (pheomelanin) produces colors that are similar to those produced by psittacofulvins. However, the differential contribution of these pigments to psittaciform phenotypic diversity has not been investigated.

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A novel analytical methodology for the extraction and determination of catecholamines (dopamine, epinephrine and norepinephrine) and their metabolites DL-3,4-dihydroxyphenyl glycol and DL-3,4-dihydroxymandelic acid by LC-MS is developed and validated for its application to human and animal urine and hair samples. The method is based on the preliminary extraction of the analytes by a magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) composite. This is followed by a <9 min chromatographic separation of the target compounds in an Onyx Monolithic C column using a mixture of 0.

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Some organisms can modulate gene expression to trigger physiological responses that help adapt to environmental stress. The synthesis of the pigment pheomelanin in melanocytes seems to be one of these responses, as it may contribute to cellular homeostasis. We experimentally induced environmental oxidative stress in male zebra finches Taeniopygia guttata by the administration of the herbicide diquat dibromide during feather growth to test if the expression of genes involved in pheomelanin synthesis shows epigenetic lability.

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Background: Melanoma is one of the highest metastatic cancers and its incidence is rapidly increasing. A great effort has been devoted to determine gene mutations and expression profiles in melanoma cells, but less attention has been given to the possible influence of melanin synthesis in melanocytes on melanomagenesis. SLC7A11 encodes the cystine/glutamate antiporter xCT and its expression increases the antioxidant capacity of cells by providing cysteine that may be used for glutathione (GSH) synthesis.

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Competitive environments promote high testosterone levels, produce oxidative stress and, consequently, impair cellular homeostasis. The regulation of genes involved in the synthesis of the pigment pheomelanin in melanocytes seems to help to maintain homeostasis against environmental oxidative stress. Here, we experimentally increased social interactions in some zebra finch (Taeniopygia guttata) males by keeping them in groups of six birds during feather growth, while others were kept alone, to test if melanocytes show epigenetic lability under a competitive social environment.

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The accumulation of the amino acid cysteine in lysosomes produces toxic substances, which are avoided by a gene (CTNS) coding for a transporter that pumps cystine out of lysosomes. Melanosomes are lysosome-related organelles that synthesize melanins, the most widespread pigments in animals. The synthesis of the orange melanin, termed pheomelanin, depends on cysteine levels because the sulfhydryl group is used to form the pigment.

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Pigments are largely responsible for the appearance of organisms. Most biological pigments derive from the metabolism of shikimic acid (melanins), mevalonic acid (carotenoids) or levulinic acid (porphyrins), which thus generate the observed diversity of external phenotypes. Starlings are generally dark birds despite iridescence in feathers, but 10% of species have evolved plumage pigmentation comprising bright colors that are known to be produced only by carotenoids.

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Even though plumage diversity is one of the most diverse phenotypic traits in nature, the reasons why some species exhibit more distinctive colors than others are poorly known. In the case of melanins, the most abundant pigments in birds, different chemical forms lead to different plumage colors and different amounts of those forms lead to different color intensities. However, the synthesis of some melanin forms is more physiologically limited than others.

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Cysteine plays essential biological roles, but excessive amounts produce cellular oxidative stress. Cysteine metabolism is mainly mediated by the enzymes cysteine dioxygenase and γ-glutamylcysteine synthetase, respectively coded by the genes CDO1 and GCLC. Here we test a new hypothesis posing that the synthesis of the pigment pheomelanin also contributes to cysteine homeostasis in melanocytes, where cysteine can enter the pheomelanogenesis pathway.

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Article Synopsis
  • * The study noted that a specific metabolite, DOPEG, was found in high concentrations in the deer’s dark ventral patch, which is linked to sexual signaling and fighting ability.
  • * These findings suggest that hormone production limits in animals may be much higher than understood before, and they reveal a unique way that urine can affect fur pigmentation.
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Pigments determine the appearance of organisms. However, pigment production can be associated with physiological constraints as in the case of pheomelanin, the sulphurated form of melanin whose synthesis in melanocytes consumes cysteine and consequently reduces the availability of glutathione (GSH) to exert antioxidant protection. Pheomelanogenesis may thus increase the susceptibility to suffer chronic oxidative stress.

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Animals living on the earth's surface are protected from the damaging effects of solar ultraviolet (UV) radiation by melanin pigments that color their integument. UV levels that reach the earth's surface vary spatially, but the role of UV exposure in shaping clinal variations in animal pigmentation has never been tested. Here, we show at a continental scale in Europe that golden eagles Aquila chrysaetos reared in territories with a high solar UV-B radiation exposure deposit lower amounts of the sulphurated form of melanin (pheomelanin) in feathers and consequently develop darker plumage phenotypes than eagles from territories with lower radiation exposure.

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Animal colouration is characterized by the concentration of pigments in integumentary structures and by the nanoscale arrangement of constitutive elements. However, the influence of molecular vibration on colour expression has been overlooked in biology. Molecular vibration occurs in the infrared spectral region, but vibrational and electronic properties can influence each other.

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