Biology subjects

San-Jose, L. M.

Publications and source records attributed to San-Jose, L. M..

3 recordsLinked to original sources

bioRxiv2025

Decoding ladybird's colours: structural mechanisms of colour production and pigment modulation.

This study investigates the mechanisms underlying colour production in the family Coccinellidae, focusing on two model species: A. bipunctata (L) and C. quatuordecimguttata (L). In this family, colours have traditionally been attributed primarily to pigments such as carotenoids and melanins. We propose an alternative perspective, considering the elytra as an integrated optical medium whose optical properties result from both its architectural design and the properties of its constituent materials, including matrix and pigments. In the present work, several methods were used, ranging from optical and electron microscopies, light-based techniques, to LC-HRMS analyses. Through local pigment analyses, microstructural examination of elytra, and modelling of interaction of elytra with light, we show that, while pigments are central to patterning and contribute to colour, overall colour also results from one or more physical mechanisms that may operate simultaneously. In the light of these results, we assume that the complex and diverse colouration in the Coccinellidae can only be elucidated by considering the interplay of pigments and the optical properties of the elytron cuticle.

evolutionary biology↗

bioRxiv2023

The genomic architecture of a continuous color polymorphism in the European barn owl (Tyto alba)

The maintenance of color polymorphism in populations has fascinated evolutionary biologists for decades. Studies of color variation in wild populations often focus on discrete color traits exhibiting simple inheritance patterns, while studies on continuously varying traits remain rare. Here, we studied the continuous white to rufous color polymorphism in the European barn owl (Tyto alba). Using a Genome Wide Association approach on whole-genome data of 75 barn owls sampled across Europe, we identified, in addition to a previously known MC1R mutation, two regions involved in this color polymorphism. We show that the combination of the three explains 80.37% (95% credible interval 58.45 to 100%) of the color variation. Among the two newly identified regions, the one on the sexual chromosome (Z) shows a large signal of differentiation in the Swiss population when contrasting individuals with different morph but the same MC1R genotype. We suggest it may play a role in the sexual dimorphism observed locally in the species. These results, uncovering two new genomic regions, provide keys to better understand the molecular bases of the color polymorphism as well as the mechanisms responsible for its maintenance in the European barn owl at both continental and local scales.

genomics↗

bioRxiv2019

Expression of glucocorticoid and mineralocorticoid receptor genes co-vary with a stress-related colour signal in barn owls

Glucocorticoid hormones are important intermediates between an organism and its environment. They enable an organism to adjust its behavioural and physiological processes in response to environmental changes by binding to mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) expressed in many tissues, including the integument. The regulation of glucocorticoids covaries with melanin-based colouration in numerous species, an association that might result from the melanocortin system and evolve within a signalling context. Most studies have focused on the circulating levels of glucocorticoids disregarding the receptors that mediate their action and could partly account for the covariation between the regulation of stress and melanin-based coloration. We investigated the association between melanin-based coloration and the gene expression levels of GR and MR but also of the melanocortin system and melanogenesis in the growing feathers of nestling barn owls (Tyto alba). We also considered the expression of genes related to the melanocortin system and melanogenesis to better understand the origin of the link between the expression of receptors to which corticosterone binds and melanin-based coloration. Nestling barn owls displaying larger black feather spots expressed GR and MR at lower levels than did smaller-spotted individuals. Because the expression of the GR and MR genes was positively, rather than negatively, correlated with the expression of melanogenic genes, we suggest that the link between melanin-based coloration, GR and MR is not directly associated to melanogenesis. The finding that the expression of GR and MR was positively associated with the expression of the PCSK2 gene (encoding the protein convertase responsible for post-translational modification of the proopiomelanocortin hormone) suggests that the melanocortin system may be implicated in the establishment of the covariation between melanism and the expression of receptors to which glucocorticoids bind. Together with previous studies, our results suggest that coloration is not only related to the production of glucocorticoids but also to the sensitivity of the integument to glucocorticoids.

physiology↗