Kin selection may act differently on genes inherited from parents (matrigenes and patrigenes), resulting in intragenomic conflict. This conflict can be observed as differential expression of matrigenes and patrigenes, or parent‐specific gene expression (PSGE). In honey bees (
Behavioural variation is essential for animals to adapt to different social and environmental conditions. The Kinship Theory of Intragenomic Conflict (KTIC) predicts that parent‐specific alleles can support different behavioural strategies to maximize allele fitness. Previous studies, including in honey bees (
- PAR ID:
- 10465026
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 32
- Issue:
- 21
- ISSN:
- 0962-1083
- Format(s):
- Medium: X Size: p. 5823-5837
- Size(s):
- p. 5823-5837
- Sponsoring Org:
- National Science Foundation
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Abstract Apis mellifera ), intragenomic conflict is hypothesized to occur in multiple social contexts. Previously, we found that patrigene‐biased expression in reproductive tissues was associated with increased reproductive potential in worker honey bees, consistent with the prediction that patrigenes are selected to promote selfish behaviour in this context. Here, we examined brain gene expression patterns to determine if PSGE is also found in other tissues. As before, the number of transcripts showing patrigene expression bias was significantly greater in the brains of reproductive vs. sterile workers, while the number of matrigene‐biased transcripts was not significantly different. Twelve transcripts out of the 374 showing PSGE in either tissue showed PSGE in both brain and reproductive tissues; this overlap was significantly greater than expected by chance. However, the majority of transcripts show PSGE only in one tissue, suggesting the epigenetic mechanisms mediating PSGE exhibit plasticity between tissues. There was no significant overlap between transcripts that showed PSGE and transcripts that were significantly differentially expressed. Weighted gene correlation network analysis identified modules which were significantly enriched in both types of transcripts, suggesting that these genes may influence each other through gene networks. Our results provide further support for the kin selection theory of intragenomic conflict, and provide valuable insights into the mechanisms which may mediate this process. -
Abstract Conflict between genes inherited from the mother (matrigenes) and the father (patrigenes) is predicted to arise during social interactions among offspring if these genes are not evenly distributed among offspring genotypes. This intragenomic conflict drives parent-specific transcription patterns in offspring resulting from parent-specific epigenetic modifications. Previous tests of the kinship theory of intragenomic conflict in honey bees (
Apis mellifera ) provided evidence in support of theoretical predictions for variation in worker reproduction, which is associated with extreme variation in morphology and behavior. However, more subtle behaviors – such as aggression – have not been extensively studied. Additionally, the canonical epigenetic mark (DNA methylation) associated with parent-specific transcription in plant and mammalian model species does not appear to play the same role as in honey bees, and thus the molecular mechanisms underlying intragenomic conflict in this species is an open area of investigation. Here, we examined the role of intragenomic conflict in shaping aggression in honey bee workers through a reciprocal cross design and Oxford Nanopore direct RNA sequencing. We attempted to probe the underlying regulatory basis of this conflict through analyses of parent-specific RNA m6A and alternative splicing patterns. We report evidence that intragenomic conflict occurs in the context of honey bee aggression, with increased paternal and maternal allele-biased transcription in aggressive compared to non-aggressive bees, and higher paternal allele-biased transcription overall. However, we found no evidence to suggest that RNA m6A or alternative splicing mediate intragenomic conflict in this species. -
SUMMARY Single‐parent expression (SPE) is defined as gene expression in only one of the two parents. SPE can arise from differential expression between parental alleles, termed non‐presence/absence (non‐PAV) SPE, or from the physical absence of a gene in one parent, termed PAV SPE. We used transcriptome data of diverse
Zea mays (maize) inbreds and hybrids, including 401 samples from five different tissues, to test for differences between these types of SPE genes. Although commonly observed, SPE is highly genotype and tissue specific. A positive correlation was observed between the genetic distance of the two inbred parents and the number of SPE genes identified. Regulatory analysis showed that PAV SPE and non‐PAV SPE genes are mainly regulated bycis effects, with a small fraction undertrans regulation. Polymorphic transposable element insertions in promoter sequences contributed to the high level ofcis regulation for PAV SPE and non‐PAV SPE genes. PAV SPE genes were more frequently expressed in hybrids than non‐PAV SPE genes. The expression of parentally silent alleles in hybrids of non‐PAV SPE genes was relatively rare but occurred in most hybrids. Non‐PAV SPE genes with expression of the silent allele in hybrids are more likely to exhibit above high parent expression level than hybrids that do not express the silent allele, leading to non‐additive expression. This study provides a comprehensive understanding of the nature of non‐PAV SPE and PAV SPE genes and their roles in gene expression complementation in maize hybrids. -
Honey bees (Apis mellifera) are an agriculturally important pollinator species that live in easily managed social groups (i.e., colonies). Unfortunately, annual losses of honey bee colonies in many parts of the world have reached unsustainable levels. Multiple abiotic and biotic stressors, including viruses, are associated with individual honey bee and colony mortality. Honey bees have evolved several antiviral defense mechanisms including conserved immune pathways (e.g., Toll, Imd, JAK/STAT) and dsRNA-triggered responses including RNA interference and a non-sequence specific dsRNA-mediated response. In addition, transcriptome analyses of virus-infected honey bees implicate an antiviral role of stress response pathways, including the heat shock response. Herein, we demonstrate that the heat shock response is antiviral in honey bees. Specifically, heat-shocked honey bees (i.e., 42 °C for 4 h) had reduced levels of the model virus, Sindbis-GFP, compared with bees maintained at a constant temperature. Virus-infection and/or heat shock resulted in differential expression of six heat shock protein encoding genes and three immune genes, many of which are positively correlated. The heat shock protein encoding and immune gene transcriptional responses observed in virus-infected bees were not completely recapitulated by administration of double stranded RNA (dsRNA), a virus-associated molecular pattern, indicating that additional virus–host interactions are involved in triggering antiviral stress response pathways.more » « less
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