Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 Nov 2;8(11):e1000506.
doi: 10.1371/journal.pbio.1000506.

The honey bee epigenomes: differential methylation of brain DNA in queens and workers

Affiliations

The honey bee epigenomes: differential methylation of brain DNA in queens and workers

Frank Lyko et al. PLoS Biol. .

Erratum in

  • PLoS Biol. 2011;9(1). doi: 10.1371/annotation/2db9ee19-faa4-43f2-af7a-c8aeacca8037

Abstract

In honey bees (Apis mellifera) the behaviorally and reproductively distinct queen and worker female castes derive from the same genome as a result of differential intake of royal jelly and are implemented in concert with DNA methylation. To determine if these very different diet-controlled phenotypes correlate with unique brain methylomes, we conducted a study to determine the methyl cytosine (mC) distribution in the brains of queens and workers at single-base-pair resolution using shotgun bisulfite sequencing technology. The whole-genome sequencing was validated by deep 454 sequencing of selected amplicons representing eight methylated genes. We found that nearly all mCs are located in CpG dinucleotides in the exons of 5,854 genes showing greater sequence conservation than non-methylated genes. Over 550 genes show significant methylation differences between queens and workers, revealing the intricate dynamics of methylation patterns. The distinctiveness of the differentially methylated genes is underscored by their intermediate CpG densities relative to drastically CpG-depleted methylated genes and to CpG-richer non-methylated genes. We find a strong correlation between methylation patterns and splicing sites including those that have the potential to generate alternative exons. We validate our genome-wide analyses by a detailed examination of two transcript variants encoded by one of the differentially methylated genes. The link between methylation and splicing is further supported by the differential methylation of genes belonging to the histone gene family. We propose that modulation of alternative splicing is one mechanism by which DNA methylation could be linked to gene regulation in the honey bee. Our study describes a level of molecular diversity previously unknown in honey bees that might be important for generating phenotypic flexibility not only during development but also in the adult post-mitotic brain.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. CpG (o/e) bias of protein-coding regions in the honey bee genome.
Since the profiles for both queens and workers are virtually identical, only the queen profile is shown.
Figure 2
Figure 2. Comparison of CpG methylation profiles in differentially methylated genes generated by two technologies, Solexa genome-wide shotgun sequencing and 454 sequencing of PCR produced amplicons.
The “heat maps” represent the 454 sequencing of PCR amplified segments, whereas the bars illustrate the Solexa reads. The eight nuclear genes for this experiment were chosen from the list of DMGs shown in Tables 3 and S2, taking into account the availability of convenient CpG-containing regions for primer design. Six genes are shown in this figure and the others in Figure 3. Gene annotations: GB18602 - membrane protein; GB18207 - cadherin; GB15132 - TAP42 (TOR signaling); GB14848 - clathrin assembly protein; GB15356 - syd, chromosome segregation; GB11061 - seryl-tRNA synthetase.
Figure 3
Figure 3. Detailed analysis of deep sequencing of selected genes.
The bisulfite converted amplicons of selected genes were sequenced using 454 technology. The selection was based on differential methylation in brains of queens and workers, but DNA from male brains (drones) was also used in this experiment. The panels illustrate the uniqueness of brain methylation patterns in bees. 3A: Genes showing similar methylation patterns in workers and drones, but a distinct methylation pattern in queens. 3B: Genes with similar methylation patterns in queens and drones, but a distinct pattern in workers. 3C: Gene with distinct methylation patterns in all three castes. Panel 3D shows the full methylation heatmaps of GB15356. This result is discussed in the chapter “Detailed Analysis of Methylation Patterns in Selected Amplicons by Deep Bisulfite Sequencing.” Gene annotations: GB18798 - ubiquitin conjugation factor; GB13464 - RhoGAP93B. For other genes, see Figure 2.
Figure 4
Figure 4. Expression profile of an alternatively spliced and differentially methylated gene GB18602 in queen and worker brains.
(A) The CpG methylation pattern indicating the level of methylation for individual CpGs (blue squares, workers; red squares, queens). (B) Gene model of GB18602 showing the two spliced variants S (short protein) and L (long protein) and the positions of PCR primers used for variant-specific amplifications. The green and orange arrows indicate the positions of two alternative Stop codons. (C) Relative expression of the two spliced variants in brains of queens and workers examined by real-time PCR. The level of transcript S (green) encoding the truncated protein is significantly up-regulated in the queen brain, whereas the L variant (orange) is expressed at the same level in both castes. The queen expression represents a combined set of data from three independent queen samples: 4 mo old (1 brain), 12 mo old (2 brains), and swarm queens of unknown age (2 brains). Workers were 8 d old (6 brains in 3 replicates). The reference gene was calmodulin . Whisker-box plot of expression ratio values: dotted line, median value; box, inter-quartile range of values; whiskers, outer 50% of observations. For more details, see Table S4.

Similar articles

Cited by

References

    1. Maleszka R. Epigenetic integration of environmental and genomic signals in honey bees: the critical interplay of nutritional, brain and reproductive networks. Epigenetics. 2008;3:188–192. - PubMed
    1. Kucharski R, Maleszka J, Foret S, Maleszka R. Nutritional control of reproductive status in honey bees via DNA methylation. Science. 2008;319:1827–1830. - PubMed
    1. Barchuk A. R, dos Santos Cristino A, Kucharski R, Simões Z. L. P, Maleszka R. Molecular determinants of caste differentiation in the highly eusocial honeybee Apis mellifera. BMC Dev Biol. 2007;7:70. - PMC - PubMed
    1. Cokus S. J, Feng S, Zhang X, Chen Z, et al. Shotgun bisulphite sequencing of the Arabidopsis genome reveals DNA methylation patterning. Nature. 2008;452:215–219. - PMC - PubMed
    1. Zemach A, McDaniel I. E, Silva P, Zilberman D. Genome-wide evolutionary analysis of eukaryotic DNA methylation. Science. 2010;328:916–919. - PubMed

Publication types