April 6, 2022

Jeffrey Staub, PhD,
Founder and Chief Scientist of Plastomics Inc.

Plastid engineering: an alternative strategy to the genetic improvements of plants

Plastid transformation technology was first developed in the model crop, tobacco, nearly 30 years ago and is routine in a small number of dicot crops. Engineering of the plastid genome has several advantages over existing technologies: introduction of transgenes via homologous recombination facilitates trait stacking, the possibility for high level transgene expression, especially in the abundant chloroplasts of leaves, and natural transgene containment due to maternal inheritance of plastids and lack of outcrossing via pollen in most crop plants. Plastomics Inc is using plastid transformation technology to introduce potentially commercial traits into soybean and is developing novel methods for monocot crops. More recently, alternative approaches to engineer plastids have been reported, including the testing of Agrobacterium or nanoparticles as delivery vehicles and base editing enzymes to create novel genetic changes. This webinar will briefly review these concepts.

Receptor-targeted next-generation bioengineered probiotics to improve gut health and prevent infectious disease

The gastrointestinal mucosa represents the first site for the dynamic interaction of the enteric pathogens with the host. Therefore, averting this critical pathogen interaction step, especially binding to host cell receptors, should help prevent infection. Two major host cell receptors, E-cadherin and Hsp60 used by Listeria monocytogenes Internalin A (InlA) and Listeria adhesion protein (LAP), respectively, were used as targets to generate our next-generation bioengineered Lactobacillus probiotics. Though the InlA-expressing probiotic was effective in vitro, LAP-expressing probiotic significantly dampened NF-?B signaling and myosin light-chain kinase (MLCK) activity and protected intestinal epithelial barrier integrity, reduced inflammatory response, and modulated immune response in mice. This probiotic also prevented fetoplacental transmission of Listeria in pregnant guinea pigs. The rational design of bioengineered probiotics targeting host cell receptors could be useful for not only improving gut health due to intimate contact of probiotics with enterocytes but also preventing infectious disease.

Dr. Adam Sowalsky, PhD
Investigator in the Laboratory of Genitourinary Cancer Pathogenesis at the National Cancer Institute

Like most human solid tumors, localized prostate is readily curable if treated early but metastatic disease is invariably lethal. The Androgen Receptor (AR) transcription factor is well established as the molecular driver of prostate cancer, and efforts to target AR show tremendous therapeutic efficacy. Nonetheless, resistance to AR-targeted therapies always develop with time. For the last decade, our laboratory examined the relationship between prostate tumor aggressivity and intratumoral heterogeneity, using patient specimens from phase two clinical trials as human model systems of tumor evolution. Although evolutionary processes related to diversity are known to be associated with increased fitness, our laboratory has recently established a direct correlation between treatment response to AR-targeted therapies and the extent of within-patient diversity prior to therapy. In this presentation, I will describe the historical context of treatment for prostate cancer, recent advances in understanding genomic alterations driving prostate cancer progression, and how the timing of these events sets the fate of a tumor to progress or respond to therapy. I will also describe efforts to improve in vitro models of prostate cancer that recapitulate the genomic complexity of disease and recent progress to target mechanisms of resistance to AR-targeted therapies.

Dr. Stanton Gelvin, PhD
H. Edwin Umbarger Distinguished Professor of Biological Sciences at Purdue University

Agrobacterium-mediated plant genetic transformation is a core technology for basic plant science and for the agricultural biotechnology industry. More than 40 years of intensive research has given us a good, if not complete, understanding of early transformation events that occur within the bacterium. This understanding has guided the research community in generating novel Agrobacterium strains with increased virulence. However, many plant species, or particular varieties/cultivars, remain highly recalcitrant to Agrobacterium-mediated transformation. To some extent, this recalcitrance is a tissue culture problem, but our understanding of the molecular events that occur in the plant cell, and plant genes/proteins contributing to transformation, lag far behind our knowledge of the events that occur within the bacterium. For the past ~25 years, our laboratory has investigated transformation processes that occur within the plant cell. Our emphasis has been on identifying plant proteins, often interacting with transferred Agrobacterium virulence (vir) effector proteins, that mediate T-strand cytoplasmic trafficking, nuclear entry, and integration into the plant genome. In this webinar, I shall discuss our current knowledge of processes which occur within the plant cell that underlie successful transformation. I shall emphasize our current understanding of how T-DNA integrates into plant chromosomes.