Molecular convergence and transgenic evidence suggest a single origin of laryngeal echolocation in bats.

The laryngeal echolocation is regarded as one of the conspicuous traits that play major roles in flourishing bats. Whether the laryngeal echolocation in bats originated once, however, is still controversial. We here address this question by performing molecular convergence analyses between ancestral branches of bats and toothed whales. Compared with controls, the molecular convergences were enriched in hearing-related genes for the last common ancestor of bats (LCAB) and extant echolocating bats, but not for the LCA of Old World fruit bats (LCAP). And the convergent hearing gene prestin of the LCAB and the extant echolocating bats functionally converged. More importantly, the high-frequency hearing of the LCAP-prestin knock-in mice decreased with lower cochlear outer hair cell function compared with the LCAB-prestin knock-in mice. Together, our findings provide multiple lines of evidence suggesting a single origin of laryngeal echolocation in the LCAB and the subsequent loss in the LCAP.

Morphological and histological analysis on the in vivo degradation of poly (propylene fumarate)/(calcium sulfate/ß-tricalcium phosphate).

Poly (propylene fumarate)/(Calcium sulfate/ß-tricalcium phosphate) (PPF/(CaSO(4)/ß-TCP)) is a kind of biodegradable composite designed for bone tissue engineering. The in vitro degradation behavior of this composite has been investigated in our previous study. The aim of this study was to investigate the effects of PPF molecular weight and CaSO(4)/ß-TCP molar ratio on the in vivo degradation of PPF/(CaSO(4)/ß-TCP) composite and the bone tissue response to PPF/(CaSO(4)/ß-TCP). Total 36 PPF/(CaSO(4)/ß-TCP) composite samples were implanted into 15.0 mm segmental defects in tibiae of 18 Japanese rabbits, harvested at 2, 4 and 8 weeks after the operation, and analyzed using radiographic and histological analysis to assess the in vivo degradation of the composites as well as tissue response to the implants. The in vivo degradation results show that all the samples maintained their original shape. Tissues penetrated into the pores which formed by the degradation of CaSO(4)/ß-TCP spheres near the surface of the composites. The rate of in vivo degradation and pore forming increased with a decrease in PPF molecular weight and an increase in CaSO(4)/ß-TCP molar ratio. No inflammatory reaction was observed after implantation, and the composites are capable of in situ pore forming. In particular, the pore forming rate can be adjusted by varying the composition of the composites. These results may indicate that PPF/(CaSO(4)/ß-TCP) is a promising osteogenic scaffold for its controllable degradation rate and excellent biocompatibility.

Genomic and functional evidence reveals molecular insights into the origin of echolocation in whales.

Echolocation allows toothed whales to adapt to underwater habitats where vision is ineffective. Because echolocation requires the ability to detect exceptional high-frequency sounds, fossils related to the auditory system can help to pinpoint the origin of echolocation in whales. However, because of conflicting interpretations of archaeocete fossils, when and how whales evolved the high-frequency hearing correlated with echolocation remain unclear. We address these questions at the molecular level by systematically investigating the convergent evolution of 7206 orthologs across 16 mammals and find that convergent genes between the last common ancestor of all whales (LCAW) and echolocating bats are not significantly enriched in functional categories related to hearing, and that convergence in hearing-related proteins between them is not stronger than that between nonecholocating mammalian lineages and echolocating bats. However, these results contrast with those of parallel analyses between the LCA of toothed whales (LCATW) and echolocating bats. Furthermore, we reconstruct the ancestral genes for the hearing protein prestin for the LCAW and LCATW; we show that the LCAW prestin exhibits the same function as that of nonecholocating mammals, but the LCATW prestin shows functional convergence with that of extant echolocating mammals. Mutagenesis shows that functional convergence of prestin is driven by convergent changes in the prestins S392A and L497M in the LCATW and echolocating bats. Our results provide genomic and functional evidence supporting the origin of high-frequency hearing in the LCAW, not the LCATW, and reveal molecular insights into the origin and evolutionary trajectories of echolocation in whales.