The COP9 signalosome controls jasmonic acid synthesis and plant responses to herbivory and pathogens.

The COP9 signalosome (CSN) is a multi-protein complex that regulates the activities of cullin-RING E3 ubiquitin ligases (CRLs). CRLs ubiquitinate proteins in order to target them for proteasomal degradation. The CSN is required for proper plant development. Here we show that the CSN also has a profound effect on plant defense responses. Silencing of genes for CSN subunits in tomato plants resulted in a mild morphological phenotype and reduced expression of wound-responsive genes in response to mechanical wounding, attack by Manduca sexta larvae, and Prosystemin over-expression. In contrast, expression of pathogenesis-related genes was increased in a stimulus-independent manner in these plants. The reduced wound response in CSN-silenced plants corresponded with reduced synthesis of jasmonic acid (JA), but levels of salicylic acid (SA) were unaltered. As a consequence, these plants exhibited reduced resistance against herbivorous M. sexta larvae and the necrotrophic fungal pathogen Botrytis cinerea. In contrast, susceptibility to tobacco mosaic virus (TMV) was not altered in CSN-silenced plants. These data demonstrate that the CSN orchestrates not only plant development but also JA-dependent plant defense responses.

Incorporating Scientific Publishing into an Undergraduate Neuroscience Course: A Case Study Using IMPULSE.

The journal IMPULSE offers undergraduates worldwide the opportunity to publish research and serve as peer reviewers for the submissions of others. Undergraduate faculty have recognized the journal's value in engaging students working in their labs in the publication process. However, integration of scientific publication into an undergraduate laboratory classroom setting has been lacking. We report here on a course at Ursinus College where 20 students taking Molecular Neurobiology were required to submit manuscripts to IMPULSE. The syllabus allowed for the laboratory research to coincide with the background research and writing of the manuscript. Students completed their projects on the impact of drugs on the Daphnia magna nervous system while producing manuscripts ready for submission by week 7 of the course. Findings from a survey completed by the students and perceptions of the faculty member teaching the course indicated that students spent much more time writing, were more focused on completing the assays, completed the assays with larger data sets, were more engaged in learning the scientific concepts and were more thorough with their revisions of the paper knowing that it might be published. Further, the professor found she was more thorough in critiquing students' papers knowing they would be externally reviewed. Incorporating journal submission into the course stimulated an in depth writing experience and allowed for a deeper exploration of the topic than students would have experienced otherwise. This case study provides evidence that IMPULSE can be successfully used as a means of incorporating scientific publication into an undergraduate laboratory science course. This approach to teaching undergraduate neuroscience allows for a larger number of students to have hands-on research and scientific publishing experience than would be possible with the current model of a few students in a faculty member's laboratory. This report illustrates that IMPULSE can be incorporated as an integral part of an academic curriculum with positive outcomes on student engagement and performance.

The tomato brassinosteroid receptor BRI1 increases binding of systemin to tobacco plasma membranes, but is not involved in systemin signaling.

The tomato wound signal systemin is perceived by a specific high-affinity, saturable, and reversible cell surface receptor. This receptor was identified as the receptor-like kinase SR160, which turned out to be identical to the brassinosteroid receptor BRI1. Recently, it has been shown that the tomato bri1 null mutant cu3 is as sensitive to systemin as wild type plants. Here we explored these contradictory findings by studying the responses of tobacco plants (Nicotiana tabacum) to systemin. A fluorescently-labeled systemin analog bound specifically to plasma membranes of tobacco suspension-cultured cells that expressed the tomato BRI1-FLAG transgene, but not to wild type tobacco cells. On the other hand, signaling responses to systemin, such as activation of mitogen-activated protein kinases and medium alkalinization, were neither increased in BRI1-FLAG-overexpressing tobacco cells nor decreased in BRI1-silenced cells as compared to levels in untransformed control cells. Furthermore, in transgenic tobacco plants BRI1-FLAG became phosphorylated on threonine residues in response to brassinolide application, but not in response to systemin. When BRI1 transcript levels were reduced by virus-induced gene silencing in tomato plants, the silenced plants displayed a phenotype characteristic of bri1 mutants. However, their response to overexpression of the Prosystemin transgene was the same as in control plants. Taken together, our data suggest that BRI1 can function as a systemin binding protein, but that binding of the ligand does not transduce the signal into the cell. This unusual behavior and the nature of the elusive systemin receptor will be discussed.