Developmental mechanisms of stripe patterns in rodents

Mammalian color patterns are among the most recognizable characters found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying their formation and subsequent evolution. Here we show that, in the African striped mouse (Rhabdomys pumilio), periodic dorsal stripes result from underlying differences in melanocyte maturation, which give rise to spatial variation in 6hair color,and we identify the transcription factor Alx3 as a regulator of this process.In 7embryonic dorsal skin, patterned expression of Alx3 foreshadows pigment stripes and acts 8to directly repress Mitf, a master regulator of melanocyte differentiation, giving rise to 9light-colored hair. Moreover, Alx3 is also upregulated in the light stripes of chipmunks, 10which have independently evolved a similar dorsal pattern.Our results reveal a 11previously unappreciated mechanism for modulating spatial variation in hair color and provide new insight into the ways in which phenotypic novelty evolves.Organismic and Evolutionary Biolog

Visual cues given by humans are not sufficient for Asian elephants (Elephas maximus) to find hidden food.

Recent research suggests that domesticated species--due to artificial selection by humans for specific, preferred behavioral traits--are better than wild animals at responding to visual cues given by humans about the location of hidden food. \Although this seems to be supported by studies on a range of domesticated (including dogs, goats and horses) and wild (including wolves and chimpanzees) animals, there is also evidence that exposure to humans positively influences the ability of both wild and domesticated animals to follow these same cues. Here, we test the performance of Asian elephants (Elephas maximus) on an object choice task that provides them with visual-only cues given by humans about the location of hidden food. Captive elephants are interesting candidates for investigating how both domestication and human exposure may impact cue-following as they represent a non-domesticated species with almost constant human interaction. As a group, the elephants (n = 7) in our study were unable to follow pointing, body orientation or a combination of both as honest signals of food location. They were, however, able to follow vocal commands with which they were already familiar in a novel context, suggesting the elephants are able to follow cues if they are sufficiently salient. Although the elephants' inability to follow the visual cues provides partial support for the domestication hypothesis, an alternative explanation is that elephants may rely more heavily on other sensory modalities, specifically olfaction and audition. Further research will be needed to rule out this alternative explanation

The FERM protein yurt is a negative regulatory component of the Crumbs complex that controls epithelial polarity and apical membrane size

SummaryThe Crumbs (Crb) complex is a key regulator of epithelial cell architecture where it promotes apical membrane formation. Here, we show that binding of the FERM protein Yurt to the cytoplasmic domain of Crb is part of a negative-feedback loop that regulates Crb activity. Yurt is predominantly a basolateral protein but is recruited by Crb to apical membranes late during epithelial development. Loss of Yurt causes an expansion of the apical membrane in embryonic epithelia and photoreceptor cells similar to Crb overexpression and in contrast to loss of Crb. Analysis of yurt crb double mutants suggests that these genes function in one pathway and that yurt negatively regulates crb. We also show that the mammalian Yurt orthologs YMO1 and EHM2 bind to mammalian Crb proteins. We propose that Yurt is part of an evolutionary conserved negative-feedback mechanism that restricts Crb complex activity in promoting apical membrane formation

Developmental mechanisms of stripe patterns in rodents

Mammalian colour patterns are among the most recognizable characteristics found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying the formation and subsequent evolution of these patterns. Here we show that, in the African striped mouse (Rhabdomys pumilio), periodic dorsal stripes result from underlying differences in melanocyte maturation, which give rise to spatial variation in hair colour. We identify the transcription factor ALX3 as a regulator of this process. In embryonic dorsal skin, patterned expression of Alx3 precedes pigment stripes and acts to directly repress Mitf, a master regulator of melanocyte differentiation, thereby giving rise to light-coloured hair. Moreover, Alx3 is upregulated in the light stripes of chipmunks, which have independently evolved a similar dorsal pattern. Our results show a previously undescribed mechanism for modulating spatial variation in hair colour and provide insights into how phenotypic novelty evolves.M.Mi. and M.V. are supported by the Spanish Ministry of Economy and Competitiveness (MINECO grants BFU2011-24245 and BFU2014-52149-R) and Instituto de Salud Carlos III. CIBERDEM is an initiative of the Instituto de Salud Carlos III. H.E.H. is an Investigator of the Howard Hughes Medical Institute.Peer reviewe

Data from: Developmental mechanisms of stripe patterns in rodents

De novo assembly of Rhabdomys pumilio transcriptome and detailed differential gene expression results This dataset contains a fasta file, including the de novo assembly of Rhabdomys pumilio transcriptome (built from RNA-Seq data using the Trinity suite of de novo transcriptome assembly tools - https://github.com/trinityrnaseq/trinityrnaseq/wiki), as well as a tab separated text file indicating the gene annotations corresponding to each assembly contig, obtained by mapping the de novo assembly to the human reference transcriptome, as described in the manuscript. A third Excel file contains the detailed results of RNA-Seq differential gene expression study in skin obtained from three dorsal regions, as described in the manuscript. Rhabdomys_pumilio.zipMammalian colour patterns are among the most recognizable characteristics found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying the formation and subsequent evolution of these patterns. Here we show that, in the African striped mouse (Rhabdomys pumilio), periodic dorsal stripes result from underlying differences in melanocyte maturation, which give rise to spatial variation in hair colour. We identify the transcription factor ALX3 as a regulator of this process. In embryonic dorsal skin, patterned expression of Alx3 precedes pigment stripes and acts to directly repress Mitf, a master regulator of melanocyte differentiation, thereby giving rise to light-coloured hair. Moreover, Alx3 is upregulated in the light stripes of chipmunks, which have independently evolved a similar dorsal pattern. Our results show a previously undescribed mechanism for modulating spatial variation in hair colour and provide insights into how phenotypic novelty evolves.Peer reviewe