Molecular Evolution of the Major Arthropod Chemoreceptor Gene Families

2019 ◽  
Vol 64 (1) ◽  
pp. 227-242 ◽  
Author(s):  
Hugh M. Robertson
Keyword(s):  
Molecular Evolution ◽  
Odorant Receptor ◽  
Gene Families ◽  
Gene Family Evolution ◽  
Gustatory Receptor ◽  
Ionotropic Receptor ◽  
Closely Related Species ◽  
Evolutionary Origins ◽  
Ligand Identification ◽  
Receptor Family

The evolutionary origins of the three major families of chemoreceptors in arthropods—the odorant receptor (OR), gustatory receptor (GR), and ionotropic receptor (IR) families—occurred at the base of the Insecta, Animalia, and Protostomia, respectively. Comparison of receptor family sizes across arthropods reveals a generally positive correlation with their widely disparate complexity of chemical ecology. Closely related species reveal the ongoing processes of gene family evolution, including gene duplication, divergence, pseudogenization, and loss, that mediate these larger patterns. Sets of paralogous receptors within species reveal positive selection on amino acids in regions likely to contribute to ligand binding and specificity. Ligands of many ORs and some GRs and IRs have been identified; however, ligand identification for many more chemoreceptors is needed, as are structures for the OR/GR superfamily, to improve our understanding of the molecular evolution of these ecologically important receptors in arthropods.

scholarly journals Description of Chemosensory Genes in Unexplored Tissues of the Moth Spodoptera littoralis

2021 ◽  
Vol 9 ◽  
Author(s):  
Fotini A. Koutroumpa ◽  
Christelle Monsempes ◽  
Marie-Christine François ◽  
Dany Severac ◽  
Nicolas Montagné ◽  
...  
Keyword(s):  
Spodoptera Littoralis ◽  
Odorant Receptor ◽  
Ectopic Expression ◽  
Gustatory Receptor ◽  
Ionotropic Receptor ◽  
Mating Partner ◽  
Large Sets ◽  
Chemosensory Genes ◽  
Female Specific ◽  
Male Specific

Illumina-based transcriptome sequencing of chemosensory organs has become a standard in deciphering the molecular bases of chemical senses in insects, especially in non-model species. A plethora of antennal transcriptomes is now available in the literature, describing large sets of chemosensory receptors and binding proteins in a diversity of species. However, little is still known on other organs such as mouthparts, legs and ovipositors, which are also known to carry chemosensory sensilla. This is the case of the noctuid Spodoptera littoralis, which has been established as a model insect species in molecular chemical ecology thanks to the description of many—but not all—chemosensory genes. To fulfill this gap, we present here an unprecedented transcriptomic survey of chemosensory tissues in this species. RNAseq from male and female proboscis, labial palps, legs and female ovipositors allowed us to annotate 115 putative chemosensory gene transcripts, including 30 novel genes in this species. Especially, we doubled the number of candidate gustatory receptor transcripts described in this species. We also evidenced ectopic expression of many chemosensory genes. Remarkably, one third of the odorant receptors were found to be expressed in the proboscis. With a total of 196 non-overlapping chemosensory genes annotated, the S. littoralis repertoire is one of the most complete in Lepidoptera. We further evaluated the expression of transcripts between males and females, pinpointing sex-specific transcripts. We identified five female-specific transcripts, including one odorant receptor, one gustatory receptor, one ionotropic receptor and one odorant-binding protein, and one male-specific gustatory receptor. Such sex-biased expression suggests that these transcripts participate in sex-specific behaviors, such as host choice for oviposition in females and/or mating partner recognition in both sexes.

scholarly journals Single-Cell Transcriptomics Reveal a Correlation between Genome Architecture and Gene Family Evolution in Ciliates

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Ying Yan ◽  
Xyrus X. Maurer-Alcalá ◽  
Rob Knight ◽  
Sergei L. Kosakovsky Pond ◽  
Laura A. Katz
Keyword(s):  
Molecular Evolution ◽  
Gene Family ◽  
Single Cell ◽  
Genome Evolution ◽  
Gene Families ◽  
Gene Family Evolution ◽  
Genome Architecture ◽  
Eukaryotic Genes ◽  
Ciliate Species ◽  
Transcript Diversity

ABSTRACT Ciliates, a eukaryotic clade that is over 1 billion years old, are defined by division of genome function between transcriptionally inactive germline micronuclei and functional somatic macronuclei. To date, most analyses of gene family evolution have been limited to cultivable model lineages (e.g., Tetrahymena, Paramecium, Oxytricha, and Stylonychia). Here, we focus on the uncultivable Karyorelictea and its understudied sister class Heterotrichea, which represent two extremes in genome architecture. Somatic macronuclei within the Karyorelictea are described as nearly diploid, while the Heterotrichea have hyperpolyploid somatic genomes. Previous analyses indicate that genome architecture impacts ciliate gene family evolution as the most diverse and largest gene families are found in lineages with extensively processed somatic genomes (i.e., possessing thousands of gene-sized chromosomes). To further assess ciliate gene family evolution, we analyzed 43 single-cell transcriptomes from 33 ciliate species representing 10 classes. Focusing on conserved eukaryotic genes, we use estimates of transcript diversity as a proxy for the number of paralogs in gene families among four focal clades: Karyorelictea, Heterotrichea, extensive fragmenters (with gene-size somatic chromosomes), and non-extensive fragmenters (with more traditional somatic chromosomes), the latter two within the subphylum Intramacronucleata. Our results show that (i) the Karyorelictea have the lowest average transcript diversity, while Heterotrichea are highest among the four groups; (ii) proteins in Karyorelictea are under the highest functional constraints, and the patterns of selection in ciliates may reflect genome architecture; and (iii) stop codon reassignments vary among members of the Heterotrichea and Spirotrichea but are conserved in other classes. IMPORTANCE To further our understanding of genome evolution in eukaryotes, we assess the relationship between patterns of molecular evolution within gene families and variable genome structures found among ciliates. We combine single-cell transcriptomics with bioinformatic tools, focusing on understudied and uncultivable lineages selected from across the ciliate tree of life. Our analyses show that genome architecture correlates with patterns of protein evolution as lineages with more canonical somatic genomes, such as the class Karyorelictea, have more conserved patterns of molecular evolution compared to other classes. This study showcases the power of single-cell transcriptomics for investigating genome architecture and evolution in uncultivable microbial lineages and provides transcriptomic resources for further research on genome evolution.

scholarly journals Expansion and accelerated evolution of 9-exon odorant receptors in Polistes paper wasps

2021 ◽  
Author(s):  
Andrew W Legan ◽  
Christopher M Jernigan ◽  
Sara E Miller ◽  
Matthieu F Fuchs ◽  
Michael J Sheehan
Keyword(s):  
Gene Family ◽  
Odorant Receptor ◽  
Receptor Gene ◽  
Gene Tree ◽  
Gene Family Evolution ◽  
Paper Wasp ◽  
Gene Copy ◽  
Evolutionary Divergence ◽  
Wasp Species ◽  
Or Gene

Abstract Independent origins of sociality in bees and ants are associated with independent expansions of particular odorant receptor (OR) gene subfamilies. In ants, one clade within the OR gene family, the 9-exon subfamily, has dramatically expanded. These receptors detect cuticular hydrocarbons (CHCs), key social signaling molecules in insects. It is unclear to what extent 9-exon OR subfamily expansion is associated with the independent evolution of sociality across Hymenoptera, warranting studies of taxa with independently derived social behavior. Here we describe odorant receptor gene family evolution in the northern paper wasp, Polistes fuscatus, and compare it to four additional paper wasp species spanning ∼40 million years of evolutionary divergence. We find 200 putatively functional OR genes in P. fuscatus, matching predictions from neuroanatomy, and more than half of these are in the 9-exon subfamily. Most OR gene expansions are tandemly arrayed at orthologous loci in Polistes genomes, and microsynteny analysis shows species-specific gain and loss of 9-exon ORs within tandem arrays. There is evidence of episodic positive diversifying selection shaping ORs in expanded subfamilies. Values of omega (d  N/dS) are higher among 9-exon ORs compared to other OR subfamilies. Within the Polistes OR gene tree, branches in the 9-exon OR clade experience relaxed negative (purifying) selection relative to other branches in the tree. Patterns of OR evolution within Polistes are consistent with 9-exon OR function in CHC perception by combinatorial coding, with both natural selection and neutral drift contributing to interspecies differences in gene copy number and sequence.

scholarly journals Amynthas corticis genome reveals molecular mechanisms behind global distribution

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xing Wang ◽  
Yi Zhang ◽  
Yufeng Zhang ◽  
Mingming Kang ◽  
Yuanbo Li ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Molecular Mechanisms ◽  
Gene Families ◽  
The Body ◽  
Gene Family Evolution ◽  
Complex Environments ◽  
Protein Coding ◽  
Itraq Analysis ◽  
Rdna Sequencing ◽  
Long Read

AbstractEarthworms (Annelida: Crassiclitellata) are widely distributed around the world due to their ancient origination as well as adaptation and invasion after introduction into new habitats over the past few centuries. Herein, we report a 1.2 Gb complete genome assembly of the earthworm Amynthas corticis based on a strategy combining third-generation long-read sequencing and Hi-C mapping. A total of 29,256 protein-coding genes are annotated in this genome. Analysis of resequencing data indicates that this earthworm is a triploid species. Furthermore, gene family evolution analysis shows that comprehensive expansion of gene families in the Amynthas corticis genome has produced more defensive functions compared with other species in Annelida. Quantitative proteomic iTRAQ analysis shows that expression of 147 proteins changed in the body of Amynthas corticis and 16 S rDNA sequencing shows that abundance of 28 microorganisms changed in the gut of Amynthas corticis when the earthworm was incubated with pathogenic Escherichia coli O157:H7. Our genome assembly provides abundant and valuable resources for the earthworm research community, serving as a first step toward uncovering the mysteries of this species, and may provide molecular level indicators of its powerful defensive functions, adaptation to complex environments and invasion ability.

scholarly journals Molecular Evolution of Drosophila Odorant Receptor Genes

2007 ◽  
Vol 24 (5) ◽  
pp. 1198-1207 ◽  
Author(s):  
Sheng Guo ◽  
Junhyong Kim
Keyword(s):  
Molecular Evolution ◽  
Odorant Receptor

scholarly journals Unique structure and positive selection promote the rapid divergence of Drosophila Y chromosomes

2021 ◽  
Author(s):  
Ching-Ho Chang ◽  
Lauren E. Gregory ◽  
Kathleen E. Gordon ◽  
Colin D. Meiklejohn ◽  
Amanda M. Larracuente
Keyword(s):  
Positive Selection ◽  
Y Chromosome ◽  
Related Species ◽  
De Novo ◽  
Gene Families ◽  
Chromosome Organization ◽  
End Joining ◽  
Sexual Antagonism ◽  
Closely Related Species ◽  
Y Chromosomes

AbstractY chromosomes across diverse species convergently evolve a gene-poor, heterochromatic organization enriched for duplicated genes, LTR retrotransposable elements, and satellite DNA. Sexual antagonism and a loss of recombination play major roles in the degeneration of young Y chromosomes. However, the processes shaping the evolution of mature, already degenerated Y chromosomes are less well-understood. Because Y chromosomes evolve rapidly, comparisons between closely related species are particularly useful. We generated de novo long read assemblies complemented with cytological validation to reveal Y chromosome organization in three closely related species of the Drosophila simulans complex, which diverged only 250,000 years ago and share >98% sequence identity. We find these Y chromosomes are divergent in their organization and repetitive DNA composition and discover new Y-linked gene families whose evolution is driven by both positive selection and gene conversion. These Y chromosomes are also enriched for large deletions, suggesting that the repair of double-strand breaks on Y chromosomes may be biased toward microhomology-mediated end joining over canonical non-homologous end-joining. We propose that this repair mechanism generally contributes to the convergent evolution of Y chromosome organization.

scholarly journals Ecological correlates of gene family size: the draft genome of the redheaded pine sawfly Neodiprion lecontei

2021 ◽  
Author(s):  
Kim Vertacnik ◽  
Danielle Herrig ◽  
R Keating Godfrey ◽  
Tom Hill ◽  
Scott Geib ◽  
...  
Keyword(s):  
Gene Family ◽  
Family Size ◽  
Draft Genome ◽  
Gene Families ◽  
Gene Family Evolution ◽  
Gene Gain ◽  
Ecological Specialization ◽  
Dietary Specialization ◽  
Pine Sawfly ◽  
Neodiprion Lecontei

A central goal in evolutionary biology is to determine the predictability of adaptive genetic changes. Despite many documented cases of convergent evolution at individual loci, little is known about the repeatability of gene family expansions and contractions. To address this void, we examined gene family evolution in the redheaded pine sawfly Neodiprion lecontei, a non-eusocial hymenopteran and exemplar of a pine-specialized lineage evolved from angiosperm-feeding ancestors. After assembling and annotating a draft genome, we manually annotated multiple gene families with chemosensory, detoxification, or immunity functions and characterized their genomic distributions and evolutionary history. Our results suggest that expansions of bitter gustatory receptor (GR), clan 3 cytochrome P450 (CYP3), and antimicrobial peptide (AMP) subfamilies may have contributed to pine adaptation. By contrast, there was no evidence of recent gene family contraction via pseudogenization. Next, we compared the number of genes in these same families across insect taxa that vary in diet, dietary specialization, and social behavior. In Hymenoptera, herbivory was associated with large GR and small olfactory receptor (OR) families, eusociality was associated with large OR and small AMP families, and--unlike investigations among more closely related taxa--ecological specialization was not related to gene family size. Overall, our results suggest that gene families that mediate ecological interactions may expand and contract predictably in response to particular selection pressures, however, the ecological drivers and temporal pace of gene gain and loss likely varies considerably across gene families.

scholarly journals Complex Molecular Evolution and Expression of Expansin Gene Families in Three Basic Diploid Species of Brassica

2020 ◽  
Vol 21 (10) ◽  
pp. 3424 ◽  
Author(s):  
Weimiao Liu ◽  
Tianqi Lyu ◽  
Liai Xu ◽  
Ziwei Hu ◽  
Xingpeng Xiong ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Diploid Species ◽  
Brassica Species ◽  
Gene Families ◽  
Structural Proteins ◽  
Development Processes ◽  
Positive Correlations ◽  
Complete Genomic

Expansins are a kind of structural proteins of the plant cell wall, and they enlarge cells by loosening the cell walls. Therefore, expansins are involved in many growth and development processes. The complete genomic sequences of Brassica rapa, Brassica oleracea and Brassica nigra provide effective platforms for researchers to study expansin genes, and can be compared with analogues in Arabidopsis thaliana. This study identified and characterized expansin families in B. rapa, B. oleracea, and B. nigra. Through the comparative analysis of phylogeny, gene structure, and physicochemical properties, the expansin families were divided into four subfamilies, and then their expansion patterns and evolution details were explored accordingly. Results showed that after the three species underwent independent evolution following their separation from A. thaliana, the expansin families in the three species had increased similarities but fewer divergences. By searching divergences of promoters and coding sequences, significant positive correlations were revealed among orthologs in A. thaliana and the three basic species. Subsequently, differential expressions indicated extensive functional divergences in the expansin families of the three species, especially in reproductive development. Hence, these results support the molecular evolution of basic Brassica species, potential functions of these genes, and genetic improvement of related crops.

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