2015AmarasinghePhd.pdf (19.91 MB)
DNA methylation, genomic imprinting and polyphenism in the bumblebee, Bombus terrestris
thesis
posted on 2015-06-29, 11:41 authored by Harindra Eranthi Amarasinghe KankanamgeGenomic imprinting, the parent-of-origin specific expression of alleles is an important
area of research in evolutionary biology and human health (cancers and developmental
syndromes). Haig’s kinship theory suggests that the maternally and paternally
derived alleles of offspring resource allocation genes have evolved under different selectional
pressures. Thus within different kin related individuals they are expressed
unequally, each allele favouring their own inclusive fitness. Social insects provide
the best independent model system to study the evolution of imprinting. However,
imprinting has not been discovered in any social insect.
My PhD lays the groundwork for a social insect model of genomic imprinting.
Methylation is a common epigenetic tag of genomic imprinting in mammals and
flowering plants. I found that a functional methylation system which is involved
in the reproductive caste formation, development and social behaviour is present
in the bumblebee, Bombus terrestris. Under queenless conditions, reproducing and
non-reproducing worker castes show different brain methylome patterns. Alteration
of methylation can cause a sterile worker to turn into a reproductive worker with
increased aggressive behaviour and ovary development. Next I found monoallelic
methylation associated with monoallelic expression in genes predicted to be imprinted
by Haig’s theory. Also, differential allele specific expression that are apparently
due to parent-of-origin effects is present in reproduction loci of B. terrestris.
Reciprocal crosses at these loci is recommended as further work, to check whether
these expression patterns are due to genomic imprinting.
I assess the effects of maternally and paternally contributed sociobiological factors on
worker male production and found that the paternity or the queen mating frequency
has a significant influence on worker male production in eusocial Hymenoptera.
Finally, I also studied the polyphenism involved in phase dependent behavioural
plasticity of locusts. I found that the transition of solitarious to fully gregarious
behaviour in the desert locust, Schistocerca gregaria begins without significant
changes in the DNA methylation landscape of the CNS but subjected to the
pronounced differences at a later stage.
History
Supervisor(s)
Mallon, EamonnDate of award
2015-06-01Author affiliation
Department of BiologyAwarding institution
University of LeicesterQualification level
- Doctoral
Qualification name
- PhD