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How Global Change Shapes Our World: Nitrogen and Salt Addition Affect Phytoplankton Morphology in a Small Freshwater Lake
(2024) Rodgers, Amanda;
Global environmental change has accelerated the deposition of nitrogen and salt into freshwaters. These changes affect the morphology of freshwater microbes, especially phytoplankton, which serve as primary producers for these ecosystems. Morphology reflects a microbe’s response to energy demands, selection, and environmental disturbance. In this pilot experiment, a handmade suspension device held samples from Cedar Bog Lake (East Bethel, MN) in three nitrogen conditions (17.6 mM NaNO3, 9 mM NaNO3, 0 mM NaNO3) crossed with two salt conditions (10 mM of NaCl or 0 mM of NaCl) plus a DI water control for BG11 media in triplicate on the surface of the lake for three weeks. I used flow cytometry to quantify community-level within-sample morphology using circle fit, area-based diameter (ABD) volume, aspect ratio, elongation, ABD area, compactness, particles/mL, and perimeter. A principal components analysis (PCA) revealed trait correlations between ABD area and ABD volume, and between circle fit, elongation, and compactness. A two-way analysis of variance (ANOVA) on the first three principal components (highly significant, accounting for 94.89% of the total variance) revealed a significant effect of nitrogen and a marginally significant effect of salt on principal component three, but no effect of treatment on the first two principal components. Nitrogen had a significant effect on particles/mL but treatment did not affect any of the other morphological traits individually. These results indicate that climate change has a complicated effect on freshwater microbial morphology at the community level. Future studies should focus on long-term changes in morphology in the field, focusing on the effects of nitrogen.
Homoeolog expression divergence contributes to time of day changes in transcriptomic and glucosinolate responses to prolonged water limitation in B. napus
(2024-07-12) Ricono, Angela; Ludwig, Ella; Casto, Anna L; Zorich , Stevan; Sumner, Joshua; Bird, Kevin; Edger, Patrick P; Hegeman, Adrian D; Gehan, Malia A; Greenham , Kathleen;; Ricono, Angela; University of Minnesota Greenham Lab
Prolonged water limitation is a recurring stress experienced by many crops, yet we have limited understanding of the mechanisms genetically complex (polyploid) crop species use to adjust growth and metabolism under these conditions. Here, we profile 16 diverse Brassica napus accessions under prolonged water limitation and uncover unique, diel homoeolog responses on the subgenome level associated with transcriptome regulation of photosynthesis, carbohydrate and sulfur metabolism, and accumulation of glucosinolate levels.
Oral History Interview with Steven M. Bellovin
(Charles Babbage Institute, 0024-07-11) Bellovin, Steven M.
This oral history interview is sponsored by and a part of NSF 2202484 “Mining a Useable Past: Perspectives, Paradoxes, and Possibilities with Security and Privacy,” at the Charles Babbage Institute, University of Minnesota. It is an interview with Percy K. and Vida L. W. Hudson Professor of Computer Science, and affiliate faculty member of the Law School Steven M. Bellovin, Columbia University, a pioneer and expert in security as well as a leading scholar in technology and law. The interview starts with Bellovin’s recollections of his pre-college and college education and how he encountered programming. He then discusses his graduate education, his mentors and professors—Fred Brooks, David Parnas, and Brian Kernighan—and their influences on him. Bellovin briefly describes and summarizes contexts to his dissertation in formal methods, “Verifiable Correct Code Generation Using Predicate Transformers.” Then the interview shifts to focus on USENET during his graduate school days and beyond. This includes sharing his thoughts on the personal computer revolution, democratizing computing, important concepts growing out of USENET such as “flame,” “sock puppet,” “trolling,” “spam,” “FAQ.” Bellovin offers context to his joining AT&T Labs and his professional focus on computer security research. He shares the context of Morris Worm, as well as the origin of cryptographic authentication, the idea of firewalls, and his work serving on the Internet Engineering Task Force or the IETF. He discusses joining Columbia University and his research and teaching. The latter part of the interview focuses on his growing focus on technology and law.