Molecular evolution of HoxA13 and the multiple origins of limbless morphologies in amphibians and reptiles

Developmental processes and their results, morphological characters, are inherited through transmission of genes regulating development. While there is ample evidence that cis-regulatory elements tend to be modular, with sequence segments dedicated to different roles, the situation for proteins is less clear, being particularly complex for transcription factors with multiple functions. Some motifs mediating protein-protein interactions may be exclusive to particular developmental roles, but it is also possible that motifs are mostly shared among different processes. Here we focus on HoxA13, a protein essential for limb development. We asked whether the HoxA13 amino acid sequence evolved similarly in three limbless clades: Gymnophiona, Amphisbaenia and Serpentes. We explored variation in ω (dN/dS) using a maximum-likelihood framework and HoxA13sequences from 47 species. Comparisons of evolutionary models provided low ω global values and no evidence that HoxA13 experienced relaxed selection in limbless clades. Branch-site models failed to detect evidence for positive selection acting on any site along branches of Amphisbaena and Gymnophiona, while three sites were identified in Serpentes. Examination of alignments did not reveal consistent sequence differences between limbed and limbless species. We conclude that HoxA13 has no modules exclusive to limb development, which may be explained by its involvement in multiple developmental processes

Review of nanomaterials in dentistry: interactions with the oral microenvironment, clinical applications, hazards, and benefits.

Interest in the use of engineered nanomaterials (ENMs) as either nanomedicines or dental materials/devices in clinical dentistry is growing. This review aims to detail the ultrafine structure, chemical composition, and reactivity of dental tissues in the context of interactions with ENMs, including the saliva, pellicle layer, and oral biofilm; then describes the applications of ENMs in dentistry in context with beneficial clinical outcomes versus potential risks. The flow rate and quality of saliva are likely to influence the behavior of ENMs in the oral cavity, but how the protein corona formed on the ENMs will alter bioavailability, or interact with the structure and proteins of the pellicle layer, as well as microbes in the biofilm, remains unclear. The tooth enamel is a dense crystalline structure that is likely to act as a barrier to ENM penetration, but underlying dentinal tubules are not. Consequently, ENMs may be used to strengthen dentine or regenerate pulp tissue. ENMs have dental applications as antibacterials for infection control, as nanofillers to improve the mechanical and bioactive properties of restoration materials, and as novel coatings on dental implants. Dentifrices and some related personal care products are already available for oral health applications. Overall, the clinical benefits generally outweigh the hazards of using ENMs in the oral cavity, and the latter should not prevent the responsible innovation of nanotechnology in dentistry. However, the clinical safety regulations for dental materials have not been specifically updated for ENMs, and some guidance on occupational health for practitioners is also needed. Knowledge gaps for future research include the formation of protein corona in the oral cavity, ENM diffusion through clinically relevant biofilms, and mechanistic investigations on how ENMs strengthen the tooth structure

Diversity of fruits consumed by three species of bats (Chiroptera : Phyllostomidae) in the Lacandona rainforest, Chiapas, Mexico

This study examined the feeding habits of three species of frugivorous bats in relation to their role as seed dispersers in two localities, one in a Neotropical rainforest area in the southern part of the Monies Azules Biosphere Reserve (REBIMA), and the other in Ejido Playon de la Gloria (PDLG). We estimated the relative abundance of Artibeus lituratus, Carollia perspicillata and Sturnira lilium. We determined the diversity and the successional category of fruits consumed by these species in both localities through the identification of seeds in their feces. The plant species diversity based on successional category showed that A. lituratus and C. perspicillata consume fruits of pioneer species as well as persistent species, while S. lilium only feeds on pioneer species. During the dry season A. lituratus and C. perspicillata had higher diversity and richness values of plant species consumed at REBIMA, whereas in the wet season they showed higher diversity and richness at PDLG, indicating that the diversity of seeds collected by both dispersers changes with the time of year. S. lilium presented higher diversity and richness values of plant species consumed at PDLG throughout the year study, indicating preference for fruits from early stages of plant succession