Carbon Cycles and Microbial Activity: Weixin Cheng is a soil ecologist whose research addresses issues of global environmental change. Cheng specializes in below ground carbon cycles and microbial activity. He began an NSF-funded pilot project to test a new technique of measuring the movement of carbon in a forest ecosystem, which promises to aid efforts to ameliorate global warming.

Plant-associated Microbes in Natural Ecosystems: Greg Gilbert's research focuses on the understanding the roles of plant-associated microorganisms in the dynamics of natural ecosystems. Ongoing research in the evolutionary ecology plant pathogens includes studies on the role of diseases in determining whether introduced plants become invasive weeds; the role of fungal diseases in regulating population and community dynamics in tropical forests; large-scale epidemiology of an invasive phytoplasma disease of coconuts, and the integration of disease ecology into conservation ecology. Additional research focuses on the diversity and structure of fungal communities across a wide range of spatial scales. Research sites include California coastal prairies, as well as lowland rain forests and mangrove forests in Central America and Australia.

Examining Chromatin and Transcription in the Yeast, Saccharomyces cerevisiae: For over a century, scientists have employed yeast as a model system to understand how basic biological systems operate. Most often, the information gained from the yeast system provides us with insights into how similar processes occur in humans. Grant Hartzog's laboratory uses biochemical and genetic techniques on the yeast Saccharomyces cerevisiae to examine the role chromatin, which consists of the DNA of our genomes and the proteins that associate with the DNA, plays in gene expression and the mechanisms by which chromatin structure is manipulated to regulate transcription. The group focuses on two proteins, Spt4 and Spt5, which form a complex and appear to modulate transcription by interacting with chromatin.

Large-scale Approaches to Study Whole-genome Archaeal Biology: Research in the Lowe laboratory combines computational and experimental approaches to investigate the biology and genetics of Archea. Archaea are microorganisms that live in some of the most extreme environments on Earth, including hot springs, thermal vents in the deep sea, and highly acidic or alkaline water. Lowe and his colleagues use high-throughput methods, such as DNA microarrays, to test and refine theoretical gene function predictions of these microorganisms and to understand how they are able to survive in such extreme conditions. Large scale collaborative approaches are used to generate leads that suggest new biology, which are then examined more closely using traditional molecular biology techniques. Current projects involve two of the most extreme hyperthermophilic Archaea sequenced to date - Pyrococcus spp. and Pyrobaculum aerophilum - both of which natively grow at boiling temperatures.

How Bacterial Pathogens Sense and Respond to Host Environments: Professor Karen Ottemann's laboratory investigates how bacteria translate chemical and physical cues in their host environment into adaptive responses. Mistakes in sensation and subsequent gene expression by bacteria may result in their elimination by the host immune response or peristaltic flow. Elucidation of such processes will hopefully lead to identification of anti-bacterial drug targets. Ottemann is particularly interested in the role of chemoreceptors and chemotaxis associated with the bacterium Helicobacter pylori. This pathogen infects some 3 billion humans and can lead to serious disease, including ulcers and cancer. Ottemann and her colleagues have discovered two of the first chemoreceptors known to aid in the process of bacterial colonization.

Novel Plant-pathogen Interactions and Invasive Species: Professor Ingrid Parker studies the ecological and evolutionary dynamics of novel interactions between plant hosts and their pathogens, primarily fungal pathogens. She is interested in understanding patterns of spread in novel epidemics. She also has several projects testing the "natural enemies hypothesis" of invasion, that biological invasions occur because introduced species are released from pest/pathogen pressure.

Microbes and Arsenic Contamination of Drinking Water: By converting the form chemical form of arsenic in the ground, natually occuring microbes have been shown to exacerbate ground water contamination by arsenic. Professor Chad Saltikov investigates the molecular biology of these microbial processes. This data promises to help divise strategies that be used to ameleorate contamination of drinking water. (Keywords: genetics, molecular biology and bioinformatics)

Genetic and Cellular Analysis of Bacteria-Host Interactions: Interactions between microbes and eukaryotic hosts have independently evolved numerous times during the history of life on our planet. Professor Sullivan's laboratory is interested in Wolbachia, an obligate intracellular bacterial endosymbiont that is present in millions of insect species. The success of these bacteria is in large part due to their ability to manipulate their host's development and germ-line processes to efficiently reproduce and transmit themselves through the host female germ-line. This has resulted in the global spread of Wolbachia. The presence of Wolbachia often has important biological consequences for the host as well. Sullivan and his colleagues are particularly interested in how Wolbachia use and manipulate host cell machinery. Specifically, they examine host cellular events involved Wolbachia-induced cytoplasmic incompatibility, replication, maternal-transmission, and centrosome-based somatic inheritance. Two species of fruit flies - Drosophila melanogaster and Drosophila simulans - are used as model systems for their investigations due to their amenability to both molecular genetic and cellular approaches.

Toxic Microalgae in Coastal Marine Systems: Toxic eukaryotic protists, including species giving rise to "harmful algal blooms" appear to be increasing world wide in the coastal oceans. Silver's lab studies various aspects of the biology and ecology of these organisms, working both on toxic diatoms in the genus Pseudo-nitzschia and on toxic dinoflagellates, including Alexandrium and Dinophysis species. Her lab is studying regional patterns of abundance of these microorganisms and the spread of the toxins through pelagic food chains, including into plankton and marine vertebrates. Additionally, she continues to do some work on eukaryotic microorganisms that, along with marine bacteria, control decomposition of organic detritus that settles from surface layers of the open ocean into water depths of 500m or more, organisms best known as inhabitants of "marine snow."

Ex-vivo Survival Mechanisms Used by Vibrio cholerae between Epidemics: Fitnat Yildiz's laboratory investigates signaling and regulatory networks of Vibrio cholerae, the causative agent of the Asiatic cholera. She and her colleagues are particularly interested in those mechanisms that allow the pathogen to adapt to changes in its habitat. The bacteria's ability to survive in different growth modes in aquatic environments is closely linked to seasonal epidemics of cholera. Yildiz's laboratory is attempting to identify and characterize genes and processes associated with phase variations of the pathogen. Their results will be useful for prediction and control of epidemics of this devastating disease.

The Roles of Microorganisms in Aquatic Ecosystems: Microbes play critical roles in the cycling of organic matter and in the biogeochemical cycles of nutrients and trace elements. Many studies involve the nitrogen cycle, with an emphasis on biological nitrogen fixation. Nitrogen fixation is an important source of biologically available nitrogen in the world's oceans. Using molecular biology approaches, including the polymerase chain reaction (PCR) and reverse-transcriptase PCR, novel nitrogen fixing cyanobacteria have been discovered in the North Pacific. Zehr's interests include the fundamental basis for the distribution of microorganisms and genetic information in the environment. Many microorganisms in the environment cannot be easily cultivated, and thus cultivation-independent approaches are needed in order to study biodiversity and biocomplexity of microbial populations. Zehr's laboratory studies the patterns of distribution of genes and genomes in aquatic systems ranging from the open ocean, to estuaries and freshwater lakes.