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In briefModes of reproduction across limbed vertebrates are diverse, but the molecular mechanisms required for the development and maintenance of reproductive tract tissue architecture are poorly understood. This paper describes gene expression changes across the regions of the reproductive tract of the adult female brown anole,Anolis sagrei. AbstractThe morphological diversity and functional role of the organs of the female reproductive system across tetrapods (limbed vertebrates) are relatively poorly understood. Although some features are morphologically similar, species-specific modification makes comparisons between species and inference about evolutionary origins challenging. In combination with the study of morphological changes, studying differences in gene expression in the adult reproductive system in diverse species can clarify the function of each organ. Here, we use the brown anole,Anolis sagrei, to study gene expression differences within the reproductive tract of the adult female. We generated gene expression profiles of four biological replicates of the three regions of the female reproductive tract, the infundibulum, glandular uterus, and nonglandular uterus, by RNA-sequencing. We aligned reads to the recently publishedA. sagreigenome and identified significantly differentially expressed genes between the regions using DESeq2. Each organ expressed approximately 14,600 genes, and comparison of gene expression profiles between organs revealed between 367 and 883 differentially expressed genes. We identify shared and region-specific transcriptional signatures for the three regions and compare gene expression in the brown anole reproductive tract to known gene expression patterns in other tetrapods. We find that genes in theHoxcluster have an anterior–posterior, collinear expression pattern as has been described in mammals. We also define a secretome for the glandular uterus. These data provide fundamental information for functional studies of the reproductive tract organs in the brown anole and an important phylogenetic anchor for comparative studies of the evolution of the female reproductive tract.
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Structure and evolution of the squamate major histocompatibility complex as revealed by two Anolis lizard genomes
The major histocompatibility complex (MHC) is an important genomic region for adaptive immunity and has long been studied in ecological and evolutionary contexts, such as disease resistance and mate and kin selection. The MHC has been investigated extensively in mammals and birds but far less so in squamate reptiles, the third major radiation of amniotes. We localized the core MHC genomic region in two squamate species, the green anole ( Anolis carolinensis ) and brown anole ( A. sagrei ), and provide the first detailed characterization of the squamate MHC, including the presence and ordering of known MHC genes in these species and comparative assessments of genomic structure and composition in MHC regions. We find that the Anolis MHC, located on chromosome 2 in both species, contains homologs of many previously-identified mammalian MHC genes in a single core MHC region. The repetitive element composition in anole MHC regions was similar to those observed in mammals but had important distinctions, such as higher proportions of DNA transposons. Moreover, longer introns and intergenic regions result in a much larger squamate MHC region (11.7 Mb and 24.6 Mb in the green and brown anole, respectively). Evolutionary analyses of MHC homologs of anoles and other representative amniotes uncovered generally monophyletic relationships between species-specific homologs and a loss of the peptide-binding domain exon 2 in one of two mhc2β gene homologs of each anole species. Signals of diversifying selection in each anole species was evident across codons of mhc1 , many of which appear functionally relevant given known structures of this protein from the green anole, chicken, and human. Altogether, our investigation fills a major gap in understanding of amniote MHC diversity and evolution and provides an important foundation for future squamate-specific or vertebrate-wide investigations of the MHC.
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- Award ID(s):
- 1812310
- PAR ID:
- 10386919
- Date Published:
- Journal Name:
- Frontiers in Genetics
- Volume:
- 13
- ISSN:
- 1664-8021
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fgene.2022.979746
