Summary Because viruses of eukaryotic algae are incredibly diverse, sweeping generalizations about their ecology are rare. These obligate parasites infect a range of algae and their diversity can be illustrated by considering that isolates range from small particles with ssRNA genomes to much larger particles with 560 kb dsDNA genomes. Molecular research has also provided clues about the extent of their diversity especially co...

Summary To determine if different algal viruses ( Phycodnaviridae ) share common patterns of seasonal abundance, quantitative PCR methods were developed and applied to monitor the abundances of three different viruses in Lake Ontario, Canada over 13 months. Throughout the year, the abundances of two different phycodnavirus polB gene fragments (LO1b‐49 and LO1a‐68) varied by more than two orders of magnitude, peaked during the...

Summary Like many estuaries, the Chesapeake Bay has pronounced gradients in salinity and nutrients. Previous studies have shown that there is a high diversity of nitrogenase ( nifH ) genes in the estuary, and that there are specific distributions of individual nifH phylotypes. In contrast to previous work that revealed the remarkable diversity of nifH phylotypes in the Chesapeake estuary, in this study of nifH expression we on...

Summary Biological nitrogen fixation is an important source of fixed nitrogen for the biosphere. Microorganisms catalyse biological nitrogen fixation with the enzyme nitrogenase, which has been highly conserved through evolution. Cloning and sequencing of one of the nitrogenase structural genes, nifH , has provided a large, rapidly expanding database of sequences from diverse terrestrial and aquatic environments. Comparison of...