Novel Insights into the Bovine Polled Phenotype and Horn Ontogenesis in Bovidae

Despite massive research efforts, the molecular etiology of bovine polledness and the developmental pathways involved in horn ontogenesis are still poorly understood. In a recent article, we provided evidence for the existence of at least two different alleles at the Polled locus and identified candidate mutations for each of them. None of these mutations was located in known coding or regulatory regions, thus adding to the complexity of understanding the molecular basis of polledness. We confirm previous results here and exhaustively identify the causative mutation for the Celtic allele (PC) and four candidate mutations for the Friesian allele (PF). We describe a previously unreported eyelash-and-eyelid phenotype associated with regular polledness, and present unique histological and gene expression data on bovine horn bud differentiation in fetuses affected by three different horn defect syndromes, as well as in wild-type controls. We propose the ectopic expression of a lincRNA in PC/p horn buds as a probable cause of horn bud agenesis. In addition, we provide evidence for an involvement of OLIG2, FOXL2 and RXFP2 in horn bud differentiation, and draw a first link between bovine, ovine and caprine Polled loci. Our results represent a first and important step in understanding the genetic pathways and key process involved in horn bud differentiation in Bovidae

Isotopes of amino acids give novel insights on nitrogen sources partitioning and trophic position of invertebrates in a subtropical mangrove

Mangrove forests are characterised by a specialised fauna with low ecological redundancy. Their faunal diversity is also decreasing across the tropics, with cascading effects on the ecosystem services provided by these forests. Traditional tools often failed to assess the importance of different sources of nutrients and a reliable trophic position estimate in mangroves, although this information is crucial to better advise on effective conservation strategies. Here, we present nitrogen and carbon isotope data of individual amino acids measured in primary producers and fauna inhabiting a subtropical mangrove. We quantified the relative importance of vascular and non-vascular source of nitrogen in the mangrove food web. We found that most gastropods mostly exclusively rely on nitrogen originating from the marine environment (non-vascular) while most brachyuran crabs integrate between 8 and 50% of their nitrogen from vascular sources, most probably by processing decaying mangrove leaves. This highlights the unique role of crabs in processing the low-nutritional mangrove leaves into the food web. Moreover, we estimated the trophic position for 17 invertebrate species inhabiting the mangrove. We highlighted previously unreported difference in term of trophic position and source of food for several species, which were previously thought to have overlapping feeding preferences. Our data thus suggest that the inherent lack of ecological redundancy present in mangrove may even be more severe than predicted by recent estimates