“The identification of candidate effectors from the genome of Striga hermonthica” and “Role of sublaterodorsal tegmental nucleus GABA neurons in sleep-wake control”

James Bradley and HanHee Lee
University of Toronto
Friday, February 14, 2020 - 11:00am
Ramsay Wright Building, Room 432
Departmental Seminar
“The identification of candidate effectors from the genome of Striga hermonthica” James Bradley Abstract: Plant parasites possess suites of genes that encode proteins capable of interacting with host biology to either facilitate host colonization or to trigger a host defence response. These proteins are popularly referred to as ‘effectors’. Striga hermonthica is a root parasitic plant that causes severe yield loss in agriculturally important cereal crops grown throughout Sub-Saharan Africa. In order to develop a durable control strategy against S. hermonthica, a better knowledge of effector-encoding genes is desired. Despite this, and in contrast with other plant parasites such as fungi and nematodes, very little is known about the nature of such genes in parasitic plants. I will describe work that investigated the genome-wide complements of effector-encoding genes from S. hermonthica. A recently assembled genome was first mined using an in silico approach to select genes encoding putative-secreted proteins, as these have the potential to be delivered from the parasite into the host plant, and thus may play a role in the host-parasite interaction. This data was then integrated with transcriptome data to identify S. hermonthica genes that were also highly upregulated during initial stages of host penetration. These analyses identified numerous putative-secreted proteins that have the potential to play a role in the S. hermonthica-host plant interaction and has facilitated the prioritisation of candidate effectors for future functional studies. “Role of sublaterodorsal tegmental nucleus GABA neurons in sleep-wake control” HanHee Lee Abstract: Rapid eye movement (REM) sleep, also known as active sleep, is characterized by elevated brain activity, loss of muscle tone with twitches and rapid eye movement. Although REM sleep has been hypothesized to play an important role in assisting learning and memory consolidation, the neuronal circuitry that controls its expression yet remains speculative. It is well documented that a brain region called the sublaterodorsal tegmental nucleus (SLD) plays an important role in controlling REM sleep; however, it is yet unclear which subtype(s) of neurons in the SLD are involved. Our lab has previously shown that glutamate neurons in the SLD play a central role in controlling REM sleep. But other published work suggests that GABA neurons in the SLD may also be involved. From this study, we used optogenetic strategies to determine if the GABA SLD neurons function to control REM sleep. We showed that optical inhibition of GABA SLD neurons terminates both REM and NREM sleep into wakefulness while optical activation of the same neurons decreases the time spent in wakefulness (p<0.05). This suggests that GABA SLD neurons function to suppress wakefulness potentially to prevent REM sleep from getting disturbed by wakefulness. Our current and previous work, therefore suggest that both glutamate and GABA SLD neurons regulate REM sleep. We propose that a glutamate-GABA microcircuit contained within the SLD functions to regulate REM sleep.
Shelley Lumba and John Peever
Dept of Cell and Systems Biology