“Secondary siRNAs from Medicago NB-LRRs modulated via miRNA-target interactions and their abundances”
Qili Fei
University of Delaware
Meyers Lab
“Exploring the diversity and ecology of viruses in the environment”
Dan Nasko
University of Delaware
Wommack Lab
“Secondary siRNAs from Medicago NB-LRRs modulated via miRNA-target interactions and their abundances”
Small RNAs are a class of noncoding RNAs which are of great importance in gene expression regulatory networks. One such family specific to plants is that of phased, secondary siRNAs (phasiRNAs). Protein-encoding genes are an important source of phasiRNAs, and the model legume Medicago truncatula generates phasiRNAs from many PHAS loci, especially disease resistance (NB-LRR) genes. We modulated miRNA abundances in transgenic tissues showing that the abundance of phasiRNAs correlates with the levels of both miRNA triggers and the target, precursor transcripts. We identified sets of phasiRNAs or PHAS loci that predominantly and substantially increase in response to miRNA overexpression. We also found that in the miRNA-mRNA target pairing, the 3’ terminal nucleotide, but not the central position, is important for phasiRNA production. Ectopic expression of Medicago NB-LRR-targeting miRNAs in Arabidopsis showed that only a few NB-LRRs are capable of phasiRNA production. Our data indicate that this might be due to target inaccessibility determined by sequences flanking target sites.
“Exploring the diversity and ecology of viruses in the environment”
There are an estimated 1031 viruses in the biosphere, making them the most abundant biological entity on Earth. That is remarkable, especially when considering the humble nature of viruses; being smaller than a wave length of light (often around 100 nm in diameter) and incapable of self-replication. Despite these limitations, viruses have a profound impact on the environment in the form of microbial host mortality and nutrient cycling. Over the last decade, DNA sequencing and methods advancements have given a greater appreciation of the diversity of viruses in the environment.
This talk will be a tour of what we know and hope to discover about viruses in the environment. Specifically, we will explore the utility of deep sequencing in discovering novel diversity of viruses from the Chesapeake Bay then discuss the role viruses may play in the human vagina and bacterial vaginosis. My goal is to provide you with a greater appreciation of the role viruses play not only in my system, but in yours as well.
Location:
University of Delaware
132 Townsend Hall
531 South College Avenue
Newark, DE 19716
Hosting Organization:
Blake Meyers
Eric Wommack
Plant & Soil Sciences
University of Delaware
Date:
September 25, 2015
Time:
12:20 - 1:15 pm