Viruses were defined as one of the two principal types of organisms
in the biosphere, namely, as capsid-encoding organisms in
contrast to ribosome-encoding organisms, i.e., all cellular life
forms. Structurally similar, apparently homologous capsids are
present in a huge variety of icosahedral viruses that infect bacteria,
archaea, and eukaryotes. These...
Studies reporting on potentially toxic interactions between aqueous fullerene nanoparticles (nC₆₀) and
microorganisms have been contradictory. When known confounding factors were avoided, growth yields of
Saccharomyces cerevisiae and Escherichia coli cultured in the presence and absence of independently prepared
lots of underivatized nC₆₀ were found not to be significantly different.
Vibrio cholerae, an etiological agent of cholera, circulates between aquatic reservoirs and the human gastrointestinal tract. The
type II secretion (T2S) system plays a pivotal role in both stages of the lifestyle by exporting multiple proteins, including cholera
toxin. Here, we studied the kinetics of expression of genes encoding the...
Cryptococcus, a major cause of disseminated infections in immunocompromised patients, kills over 600,000 people per year
worldwide. Genes involved in the virulence of the meningitis-causing fungus are being characterized at an increasing rate, and to
date, at least 648 Cryptococcus gene names have been published. However, these data are scattered...
Successful host cell colonization by the Q fever pathogen, Coxiella burnetii, requires translocation of effector proteins into
the host cytosol by a Dot/Icm type 4B secretion system (T4BSS). In Legionella pneumophila, the two-component system (TCS)
PmrAB regulates the Dot/Icm T4BSS and several additional physiological processes associated with pathogenesis. Because PmrA...
Quantitative real-time PCR (qPCR) assays that target the human-associated HF183 bacterial cluster within members of the genus Bacteroides are among the most widely used methods for the characterization of human fecal pollution in ambient surface waters. In this study, we show that a current TaqMan HF183 qPCR assay (HF183/BFDrev) routinely...
Many bacteria possess cell density-dependent quorum-sensing (QS) systems that often regulate cooperative secretions involved
in host-microbe or microbe-microbe interactions. These secretions, or “public goods,” are frequently coregulated by stress and
starvation responses. Here we provide a physiological rationale for such regulatory complexity in the opportunistic pathogen
Pseudomonas aeruginosa. Using minimal-medium...
Engaging large numbers of undergraduates in authentic scientific discovery is desirable but difficult to achieve. We
have developed a general model in which faculty and teaching assistants from diverse academic institutions are trained to teach a
research course for first-year undergraduate students focused on bacteriophage discovery and genomics. The course...
We used metatranscriptomics to study the gene transcription patterns of microbial plankton (0.2 to 64 μm) at a mesohaline station
in the Chesapeake Bay under transitions from oxic to anoxic waters in spring and from anoxic to oxic waters in autumn.
Samples were collected from surface (i.e., above pycnocline) waters...
The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first
is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional,
dominant-negative mutant located in an operon that is inducible by the...