Session VIIA

Wednesday, May 18th

Session VIIA


Identification of Photosynthetic and Microbial Communities in Freshwater Microbialites of Fayetteville Green Lake Using Biomarker Analysis

Tyler Shields and Mark Teece


Freshwater microbialites are living carbonate structures that grow in a small number of lakes throughout the world.  Microbialites are composed of an outer active microbial mat that is contains various autotrophic and heterotrophic microbial communities. These organisms precipitate carbonate to produce the skeleton of the microbialites structure. We used biomarker analysis to determine the composition of autotrophic and heterotrophic organisms within the microbialites of Fayetteville Green Lake, near Syracuse NY. Autotrophic and heterotrophic biomarkers were detected in the microbialites.  Bacterial biomarkers were identified and included odd length C15 and C17 fatty acids and trace amounts of hopanoids were also identified in shallow water microbialites.  Autotrophic biomarkers were identified and included all even carbon chain length fatty acids from C16-C24.  Phytol which is present in chlorophyll was also detected. A wide range of steroidal compounds were identified that are typically present in photosynthetic organisms and included cholesterol and brassicasterol. The biomarker compositions of microbialites are hypothesized to change as a function of spatial location and depth within the water column of Green Lake. We hypothesize that light is a major factor determining the composition of the heterotrophic and autotrophic communities in freshwater microbialites.         


Synthesis of Pancratistatin from Narciclasine by Reductive Transposition

Ringaile Lapinskaite, Chelsea Rintelmann, and Tomas Hudlicky

Brock University, Department of Chemistry

Narciclasine and pancratistatin are biologically active alkaloids from the Amaryllidaceae family. This presentation will focus on the application of a reductive transposition strategy for the transformation of natural or synthetic narciclasine to the less abundant alkaloid, pancratistatin. Selective inversion of the allylic alcohol and subsequent reductive transposition yields the required stereochemistry at the benzylic position and an olefin, which can be used as the chemical handle for the installation of pancratistatin's Trans diol moiety.


Novel Selenorhodamine Dyes as Photosensitizers in Extracorporeal Photopheresis

Jacqueline Hill, Dr. Michael Detty, Dr. Gregory Schamerhorn, and Dr. Mark Kryman

University at Buffalo, Department of Chemistry

Rhodamine dyes have found wide use as fluorescent probes due to their preferential uptake in the mitochondria and selective accumulation in carcinoma cells. One of the most well-known rhodamines, Rhodamine-123, utilizes a xanthylium core with an oxygen heteroatom. The Detty lab has focused on synthesizing analogues of Rhodamine-123 with varying heavy chalcogens (S, Se, and Te), core modifications (half-julolidyl, julolidyl, and bis compounds), as well as amide and thioamide substituents at the 9-position of the core. These compounds have been tested as photosensitizers in the photodynamic therapy (PDT) of cancer and, more recently, in extracorporeal photopheresis (ECP) following hematopoietic stem cell transplantations (HSCT). Current synthesis is focused on improving upon the half-julolidyl and bis half-julolidyl cores by way of novel selenorhodamine dyes with a bis gem-dimethyl julolidine core. Following the completed synthesis, these dyes will be tested as photosensitizers in ECP with improved patient outcomes predicted.


The Role of Life History Strategy on PCB Bioaccumulation and Biomagnification in Finger Lakes Mysis Diluviana Populations

Caitlin Slife and Dr. Gordon Paterson


The freshwater mysid shrimp (Mysis diluviana) is a glacial relict species that is native throughout the Great Lakes basin.  With lipid contents ranging up to 40% of dry weight and relatively large body sizes (20mm), mysids represent an important prey resource for multiple fish species.  Mysid populations can have life history strategies ranging from 1 – 4 years which greatly contrasts the shorter seasonal lifespans of smaller pelagic zooplankton species.  During daytime feeding, mysids will consume sediment materials which also represent the primary sink of persistent organic pollutants such as polychlorinated biphenyls (PCBs) in freshwater ecosystems.  The mysid’s diel vertical migration patterns then link benthic and pelagic food webs and transport these organic contaminants.  PCBs are highly hydrophobic pollutants that bioaccumulate and biomagnify in the lipid fraction of biota.  Mysid’s high fat content, vertical migration behavior, and long life relative to other zooplankton suggest that they represent a significant source of these pollutants to higher trophic level consumers.  We hypothesize that PCB bioaccumulation and biomagnification in mysid populations will be positively correlated with population life history strategy, with increased bioaccumulation and biomagnification observed in ecosystems where mysids have longer life history strategies.


Central Role of the Copper-Binding Motif in the Complex Mechanism of Action of Ixosin: Enhancing Oxidative Damage and Promoting Synergy with Ixosin B

M. Daben Libardo, Vitaliy Gorbatyuk, and Alfredo Angeles-Boza

University of Connecticut

Ticks transmit multiple pathogens to different hosts without compromising their health. Their ability to evade microbial infections are largely a result of their effective innate immune response including various antimicrobial peptides. Therefore, a deep understanding of how ticks (and other arthropod vectors) control microbial loads could lead to the design of broad-spectrum antimicrobial agents. In this report we study the role of the Amino Terminal Copper- and Nickel- (ATCUN) binding sequence in the peptide Ixosin, isolated from the salivary glands of the hard tick Ixodes sinensis. Our results indicate that the ATCUN motif is not essential to the potency of Ixosin, but is indispensable to its oxidative mechanism of action. Specifically, the ATCUN motif promotes dioxygen- and copper-dependent lipid (per) oxidation of bacterial membranes in a temporal fashion coinciding with the onset of bacterial death. Microscopy and studies on model membranes indicate that the oxidized phospholipids are utilized as potential targets of Ixosin B (another tick salvary gland peptide) involving its delocalization to the bacterial membrane, thus resulting in a synergistic effect. Our proposed mechanism of action highlights the centrality of the ATCUN motif to ixosin’s mechanism of action and demonstrate a novel way in which (tick) AMPs utilize metal ions in its activity. This study suggests that ticks employ a variety of effectors to generate an amplified immune response, possibly justifying its vector competence.