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Annual Work Seminars on Monday, Jun 28, 2021

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Digvijay Lalwani
Thesis Committee Members
WhereRemote Video Conference
When Monday, Jun 28, 2021 04:00 PM

Not disclosed yet!

The neural basis for ecological speciation in Tephritidae fruit flies (Rhagoletis pomonella)

Hinal Khaarva
Supervisors Shannon B Olsson
Thesis Committee Members Gaiti Hasan, Axel Brockmann
WhereRemote Video Conference
When Monday, Jun 28, 2021 04:00 PM

In temperate region, life history timing is one of the most important ecological barriers which separates host plant and their specific insects. We are studying the neural mechanism for ecological speciation in Rhagoletis sp. (Diptera: Tephritide). This speciation is being observed over the past 300 years in North America. The introduction of domesticated apples (Malus pumila) by European colonists around 1800-1850 caused a shift in host preference by these flies from their native host downy hawthorn (Crataegus mollis). However, the question of how such a rapid and specific change in host preferences could occur in such a short period of evolutionary time remains unanswered. In insects, metamorphosis brings profound reorganization and transformation of the nervous system. Neurotransmitters, neurohormones are known to play a vital role in development and adult behavior. 

Apple and Hawthorn fly undergoes pupal diapause during winter, and apple flies initiate and terminate diapause at a different times than hawthorn flies. Here, we hypothesize that neuromodulators, which are known to regulate different behaviors in insects, could also be responsible for affecting timing during developmental stages and potentially host preference in these races.

Using liquid chromatography-mass spectrometry (LC-MS), I quantified the levels of various neurotransmitters from the brain of developing pupal and adult R. pomonella. The quantification of neurotransmitters shows significant differences in certain chemicals, including tyrosine and octopamine. Interestingly, our data suggest apple flies exhibit adult neurogenesis nearly three weeks faster than hawthorn flies (day 20 vs. day 40), but their neurotransmitter production does not increase accordingly.

Investigating the role of RNA directed DNA Methylation pathway in rice genomic imprinting

Avik Pal
Supervisors Shivaprasad P V
Thesis Committee Members Ranabir Das, Dimple Notani, Anjana Badrinarayanan
WhereRemote Video Conference
When Monday, Jun 28, 2021 04:00 PM

Genomic imprinting is an unequal expression of maternal and paternal alleles based on the parent of origin. Unlike placental mammals, genomic imprinting is restricted in the placenta-like organ of flowering plants called endosperm. Influence of small RNA-based epigenetic modifications were thought to be the major players in genomic imprinting. However, it is not known how epigenetic modifications induced by small RNA directed DNA Methylation (RdDM) pathway initiates and maintains genomic imprinting in crop plants. In this work, I envisage to investigate the role of RdDM pathway regulators in rice genome imprinting. I identified a chromatin remodeler named OsCLSY3, that is likely to play a crucial role in rice imprinting based on whole-genome expression analysis.  This RdDM-associated gene itself is imprinted in rice endosperm and expressed only in the reproductive tissues. My analysis suggests that it is likely an upstream candidate of RdDM pathway to influence imprinting of other genes. Using genetic, genomic and biochemical approaches, the role of this yet uncharacterized RdDM player and its close homologs in rice endosperm development and genomic imprinting.

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