Peer Review #1 of "Allele specific expression and methylation in the bumblebee, Bombus terrestris (v0.2)"

Genomic imprinting is the differential expression of alleles, with the expression being dependent upon the sex of the parent from which it was inherited. Hymenopteran insects (ants, bees and wasps) are emerging as potential models for genomic imprinting and epigenetics. As a first step in establishing the possibility of genomic imprinting in the bumblebee, Bombus terrestris, we search for allele specific expression in twelve genes associated with worker reproduction. We found that the patrigene (allele from the father) is more expressed than the matrigene (allele from the mother) in Ecdysone 20 monooxygenase. This enzyme catalyses the reaction which turns the ecdysteroid ecdysone into 20-hydroxyecdysone, also an ecdysteroid. Both of these ecdysteroids are important for worker reproduction in the bumblebee.

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Allele specific expression and methylation in the bumblebee, Bombus terrestris

PeerJ ◽

10.7717/peerj.3798 ◽

2017 ◽

Vol 5 ◽

pp. e3798 ◽

Cited By ~ 9

Author(s):

Zoë Lonsdale ◽

Kate Lee ◽

Maria Kiriakidu ◽

Harindra Amarasinghe ◽

Despina Nathanael ◽

...

Keyword(s):

Bombus Terrestris ◽

Social Hymenoptera ◽

Specific Expression ◽

Allele Specific Expression ◽

Epigenetic Marker ◽

The Social ◽

Allele Specific ◽

Contradictory Evidence ◽

Allele Specific Methylation

The social hymenoptera are emerging as models for epigenetics. DNA methylation, the addition of a methyl group, is a common epigenetic marker. In mammals and flowering plants methylation affects allele specific expression. There is contradictory evidence for the role of methylation on allele specific expression in social insects. The aim of this paper is to investigate allele specific expression and monoallelic methylation in the bumblebee, Bombus terrestris. We found nineteen genes that were both monoallelically methylated and monoallelically expressed in a single bee. Fourteen of these genes express the hypermethylated allele, while the other five express the hypomethylated allele. We also searched for allele specific expression in twenty-nine published RNA-seq libraries. We found 555 loci with allele-specific expression. We discuss our results with reference to the functional role of methylation in gene expression in insects and in the as yet unquantified role of genetic cis effects in insect allele specific methylation and expression.

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Bumblebee worker castes show differences in allele-specific DNA methylation and allele-specific expression

10.1101/2020.02.07.938423 ◽

2020 ◽

Author(s):

H. Marshall ◽

A.R.C. Jones ◽

Z.N. Lonsdale ◽

E.B. Mallon

Keyword(s):

Dna Methylation ◽

Bombus Terrestris ◽

Imprinted Genes ◽

Specific Expression ◽

Allele Specific Expression ◽

Genome Wide ◽

Expression Bias ◽

Allele Specific ◽

Parent Of Origin ◽

Worker Castes

AbstractAllele-specific expression is when one allele of a gene shows higher levels of expression compared to the other allele, in a diploid organism. Genomic imprinting is an extreme example of this, where some genes exhibit allele-specific expression in a parent-of-origin manner. Recent work has identified potentially imprinted genes in species of Hymenoptera. However, the molecular mechanism which drives this allelic expression bias remains unknown. In mammals DNA methylation is often associated with imprinted genes. DNA methylation systems have been described in species of Hymenoptera, providing a candidate imprinting mechanism. Using previously generated RNA-Seq and whole genome bisulfite sequencing from reproductive and sterile bumblebee (Bombus terrestris) workers we have identified genome-wide allele-specific expression and allele-specific DNA methylation. The majority of genes displaying allele-specific expression are common between reproductive castes and the proportion of allele-specific expression bias generally varies between colonies. We have also identified genome-wide allele-specific DNA methylation patterns in both castes. There is no significant overlap between genes showing allele-specific expression and allele-specific methylation. These results indicate that DNA methylation does not directly drive genome-wide allele-specific expression in this species. Only a small number of the genes identified may be ‘imprinted’ and it may be these genes which are associated with allele-specific DNA methylation. Future work utilising reciprocal crosses to identify parent-of-origin DNA methylation will further clarify the role of DNA methylation in parent-of-origin allele-specific expression.

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