Bat laryngeal echolocation is considered as one of the most complex and diverse modes of auditory sensory perception in animals and its evolutionary history has been the cause of many scientific controversies in the past two decades. To date, the majority of scientific evidence supports that bats (Chiroptera) are divided into two subordinal groups: Yinpterochiroptera, containing the laryngeal echolocating superfamily Rhinolophidae as sister taxa to the non-laryngeal echolocating family Pteropodidae; and Yangochiroptera, containing all other laryngeal echolocating lineages. This topology has led to an unanswered question in mammalian biology: was laryngeal echolocation lost in the ancestral pteropodids or gained convergently in the echolocating bat lineages? To date, there is insufficient and conflicting evidence from fossil, genomic, morphological and phylogenomic data to resolve this question. We detail an ontogenetic study of fetal cochlear development from seven species of bats and five outgroup mammals and show that in early fetal development, all bats including the non-laryngeal echolocating pteropodids have a similarly large cochlea typically associated with laryngeal echolocation abilities. The subsequent cochlear growth rate in the pteropodids is the slowest of all mammals and leads to the pteropodids and the non-echolocating lineages eventually sharing a similar cochlear morphospace as adults. The results suggest that pteropodids maintain a vestigial developmental stage indicative of past echolocation capabilities and thus support a single origin of laryngeal echolocation in bats.
BackgroundInducing beige fat from white adipose tissue (WAT) is considered to be a shortcut to weight loss and increasingly becoming a key area in research into treatments for obesity and related diseases. However, currently, animal models of beige fat are restricted to rodents, where subcutaneous adipose tissue (sWAT, benign WAT) is more liable to develop into the beige fat under specific activators than the intra-abdominal adipose tissue (aWAT, malignant WAT) that is the major source of obesity related diseases in humans.MethodsHere we induced beige fat by cold exposure in two species of bats, the great roundleaf bat (Hipposideros armiger) and the rickett's big-footed bat (Myotis ricketti), and compared the molecular and morphological changes with those seen in the mouse. Expression of thermogenic genes (Ucp1 and Pgc1a) was measured by RT-qPCR and adipocyte morphology examined by HE staining at three adipose locations, sWAT, aWAT and iBAT (interscapular brown adipose tissue).ResultsExpression of Ucp1 and Pgc1a was significantly upregulated, by 729 and 23 fold, respectively, in aWAT of the great roundleaf bat after exposure to 10°C for 7 days. Adipocyte diameters of WATs became significantly reduced and the white adipocytes became brown-like in morphology. In mice, similar changes were found in the sWAT, but much lower amounts of changes in aWAT were seen. Interestingly, the rickett's big-footed bat did not show such a tendency in beige fat.ConclusionsThe great roundleaf bat is potentially a good animal model for human aWAT browning research. Combined with rodent models, this model should be helpful for finding therapies for reducing harmful aWAT in humans.
Reduced numbers of carpal and tarsal bones (wrist and ankle joints) are extensively observed in the clade of Cetacea and Ruminantia (Cetruminantia). Homebox D11 (Hoxd11) is one of the important genes required for limb development in mammals. Mutations in Hoxd11 can lead to defects in particular bones of limbs, including carpus and tarsus. To test whether evolutionary changes in Hoxd11 underlie the loss of these bones in Cetruminantia, we sequenced and analyzed Hoxd11 coding sequences and compared them with other 59 HoxA and HoxD genes in a taxonomic coverage of Cetacea, Ruminantia and other mammalian relatives. Statistical tests on the Hoxd11 sequences found an accelerated evolution in the common ancestor of cetaceans and ruminants, which coincided with the reduction of carpal and tarsal bones in this clade. Five amino acid substitutions (G222S, G227A, G229S, A240T and G261V) and one amino acid deletion (G254Del) occurred in this lineage. In contrast, other 59 HoxA and HoxD genes do not show this same evolutionary pattern, but instead display a highly conserved pattern of evolution in this lineage. Accelerated evolution of Hoxd11, but not other 59 HoxA and HoxD genes, is probably related to the reduction of the carpal and tarsal bones in Cetruminantia. Moreover, we found two amino acid substitutions (G110S and D223N) in Hoxd11 that are unique to the lineage of Cetacea, which coincided with hindlimb loss in the common ancestor of cetaceans. Our results give molecular evidence of Hoxd11 adaptive evolution in cetaceans and ruminants, which could be correlated with limb morphological adaptation. KEYWORDS
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.