Phylogenetic Diversity of Microbial Isolates from the Mars Pathfinder

As spacecraft are sent to different planets, they take with them microscopic pieces of life from Earth. It is the task of the Biotechnology and Planetary Protection Group to keep as much of this life off other planets as possible as well as document any life that may have been sent. During the construction of the Mars Pathfinder, samples were collected from various locations on the spacecraft to test for contamination. These samples were then isolated, grown, documented, preserved and their 16S rRNA genes were sequenced for identification. The 16S rRNA gene sequence is utilized because it is a highly conserved portion of the transcriptional machinery of bacteria but also has known variable regions allowing it to be and amplified and used for distinguishing different genera and species of microbial life. All of the bacterial strains analyzed from this study were members of the genus Bacillus. Seventeen strains were sequenced and identified at greater than 98% homology to known type strains. After identifying the bacterial contaminant types, the National Aeronautics and Space Administration’s Jet Propulsion Laboratory will be able to better determine cleanliness protocols to maintain the international standard and protect Mars from Earth contamination on future missions

Zooplankton Trophic Ecology in the San Francisco Estuary During Summer as Determined by Stable Isotope Analysis

Declines in the abundance of several pelagic fish species in the upper San Francisco Estuary have prompted investigation into food web interactions within the estuary and delta (the lower Sacramento and San Joaquin Rivers). This area is characterized by low primary production and pelagic food webs much longer and reticulated than previously thought, implying low efficiency in the energy transfers from primary producers to planktivorous fish. We determined the carbon and nitrogen stable isotope (SI) composition of zooplankton samples collected monthly between June 2012 and February 2013 at eight stations along the salinity gradient. As consumers SI composition reflects that of their food, we use it to identify the sources of organic matter and to describe trophic relationships among the different species. Our preliminary results indicate that most species have SI compositions consistent with a diet based on phytoplankton in June and July and that they do not seem to consume Microcystis (toxic cyanobacteria developing in large blooms in the low salinity/freshwater part of the system). Nevertheless, the overlap between phytoplankton SI composition and the one expected for vascular/C3 plants prevents us from definitely ruling out organic detritus-bacteria-microzooplankton-zooplankton as an alternative trophic pathway

Discovery of an Apoptosis Inducing Ligand for Burkitt Lymphoma

One-bead two-compound (OB2C) combinatorial chemistry libraries enable the discovery of novel synthetic compounds which can be used to evoke specific signaling response in cells. The library configuration is composed of a fixed known cell adhesion ligand and a random chemical library displayed on the surface of Tentagel beads. The cell adhesion ligand binds to specific receptors located on the surface of cells enabling the random immobilized chemical molecules on each bead resin bead to evoke specific cellular responses such as apoptosis or cell death. To validate this concept, a OB2C combinatorial library comprised of an α4β1 integrin targeting ligand, LLP2A, and a novel self-folding tricyclic branched hexamer random library were screened against various hematological and epithelial cancer cell lines: Raji, Molt4, Jurkat, TK6, and PC3N. These cells were incubated with library beads for 48 hours in 6 well tissue culture plates. Propidium iodide, a DNA intercalating agent, is then added to each well to evaluate cell viability. When visualized under a fluorescent microscope, with wavelength excited at 488 nm, cells bound to the OB2C libraries will fluoresce red, indicating apoptosis. From the Raji cell line screening, one bead from the LDO2A-LLP2A library was selected for invoking apoptosis. The morphological appearance of the cells bound to this bead were: blebbing, cell shrinkage, nuclear fragmentation, chromatin fragmentation, and chromosomal DNA fragmentation. Further sequencing via Edman degradation will be performed to identify the amino acid sequence. This chemical approach has the potential to target and kill Burkitt lymphoma