Project description:We used whole bodies of four different adult fire ant morphs (alate queens, workers, haploid males, and diploid males) from a single polygyne colony to generate single-base resolution DNA methylation maps.
Project description:Queen discrimination behavior in the red imported fire ant Solenopsis invicta maintains its two types of societies: colonies with one (monogyne) or many (polygyne) queens, yet the underlying genetic mechanism is poorly understood. This behavior is controlled by two supergene alleles, SB and Sb, with ~600 genes. Polygyne workers, having either the SB/SB or SB/Sb genotype, accept additional SB/Sb queens into their colonies but kill SB/SB queens. While monogyne workers, all SB/SB, reject all additional queens regardless of genotype. Because the SB and Sb alleles do not recombine, it is difficult to determine which genes within the supergene mediate this differential worker behavior. We hypothesized that the alternate worker genotypes sense queens differently because of different patterns of gene expression in their main sensory organ, the antennae. To identify such differentially expressed genes, we sequenced RNA from four biological replicates of pooled antennae from three groups of workers: monogyne SB/SB, polygyne SB/SB, and polygyne SB/Sb. We identified 81 differentially expressed protein coding genes with 14 encoding potential odor metabolism and perception proteins. We focused on the two differentially expressed odorant perception genes: an odorant binding protein SiOBP12 and an odorant receptor SiOR463. We found that the SiOR463 was lost in the Sb-genome. In contrast, the SiOBP12 has an Sb-specific duplication SiOBP12b’, which was expressed in the SB/Sb worker antennae, while both paralogs SiOBP12 and SiOBP12b’ were expressed in the body. This result indicates that SiOBP12b’ has gained an antennal promoter or enhancer and suggests neofunctionalization, perhaps for queen discrimination behavior.
Project description:Queen discrimination behavior in the red imported fire ant Solenopsis invicta maintains its two types of societies: colonies with one (monogyne) or many (polygyne) queens, yet the underlying genetic mechanism is poorly understood. This behavior is controlled by two supergene alleles, SB and Sb, with ~600 genes. Polygyne workers, having either the SB/SB or SB/Sb genotype, accept additional SB/Sb queens into their colonies but kill SB/SB queens. While monogyne workers, all SB/SB, reject all additional queens regardless of genotype. Because the SB and Sb alleles do not recombine, it is difficult to determine which genes within the supergene mediate this differential worker behavior. We hypothesized that the alternate worker genotypes sense queens differently because of different patterns of gene expression in their main sensory organ, the antennae. To identify such differentially expressed genes, we sequenced RNA from four biological replicates of pooled antennae from three groups of workers: monogyne SB/SB, polygyne SB/SB, and polygyne SB/Sb. We identified 81 differentially expressed protein coding genes with 14 encoding potential odor metabolism and perception proteins. We focused on the two differentially expressed odorant perception genes: an odorant binding protein SiOBP12 and an odorant receptor SiOR463. We found that the SiOR463 was lost in the Sb-genome. In contrast, the SiOBP12 has an Sb-specific duplication SiOBP12b’, which was expressed in the SB/Sb worker antennae, while both paralogs SiOBP12 and SiOBP12b’ were expressed in the body. This result indicates that SiOBP12b’ has gained an antennal promoter or enhancer and suggests neofunctionalization, perhaps for queen discrimination behavior.
Project description:Queen discrimination behavior in the red imported fire ant Solenopsis invicta maintains its two types of societies: colonies with one (monogyne) or many (polygyne) queens, yet the underlying genetic mechanism is poorly understood. This behavior is controlled by two supergene alleles, SB and Sb, with ~600 genes. Polygyne workers, having either the SB/SB or SB/Sb genotype, accept additional SB/Sb queens into their colonies but kill SB/SB queens. While monogyne workers, all SB/SB, reject all additional queens regardless of genotype. Because the SB and Sb alleles do not recombine, it is difficult to determine which genes within the supergene mediate this differential worker behavior. We hypothesized that the alternate worker genotypes sense queens differently because of different patterns of gene expression in their main sensory organ, the antennae. To identify such differentially expressed genes, we sequenced RNA from four biological replicates of pooled antennae from three groups of workers: monogyne SB/SB, polygyne SB/SB, and polygyne SB/Sb. We identified 81 differentially expressed protein coding genes with 14 encoding potential odor metabolism and perception proteins. We focused on the two differentially expressed odorant perception genes: an odorant binding protein SiOBP12 and an odorant receptor SiOR463. We found that the SiOR463 was lost in the Sb-genome. In contrast, the SiOBP12 has an Sb-specific duplication SiOBP12b’, which was expressed in the SB/Sb worker antennae, while both paralogs SiOBP12 and SiOBP12b’ were expressed in the body. This result indicates that SiOBP12b’ has gained an antennal promoter or enhancer and suggests neofunctionalization, perhaps for queen discrimination behavior.
Project description:To investigate the effect of supergene status and social environment pre- and post-pupation, we used RNA-sequencing of fire ant ant workers to assess gene expression differences.
Project description:We used whole bodies of four different adult fire ant morphs (alate queens, workers, haploid males, and diploid males) from a single polygyne colony to generate single-base resolution DNA methylation maps. DNA was extracted from whole bodies of individual males, individual queens, and pooled workers. Bisulfite conversion and sequencing was performed by Beijing Genomics Institute (Shenzhen, China). Unmethylated enterobacteria phage lambda DNA (GenBank accession: J02459.1) was added to each genomic DNA sample as a control for bisulfite conversion efficiency.
Project description:We used whole-genome fire ant microarrays to examine the molecular basis for division of labor in fire ant workers by comparing foraging and non-foraging workers from monogyne colonies. Fire ant colonies were collected in the field and transported into the lab were they were reared in standard conditions. We created a nesting chamber containing the queen, the brood and workers performing nursing tasks and a foraging area, separated from the nesting chamber and provided with food and water sources. Foraging workers were collected in the foraging area while non-foraging workers were collected in the nesting chamber. Total RNA was isolated from pools of whole workers and processed for microarrays.