Summary Oceanic photosynthetic picoeukaryotes ( 40% of total primary production at low latitudes such as the North‐Eastern tropical Atlantic. In the world ocean, warmed by climate changes, the expected gradual shift towards smaller primary producers could render the role of photosynthetic picoeukaryotes even more important than they are today. Little is still known, however, about how the taxonomic composition of this highly d...

Summary The vast majority of cyanophages isolated to date are cyanomyoviruses, a group related to bacteriophage T4. Comparative genome analysis of five cyanomyoviruses, including a newly sequenced cyanophage S‐RSM4, revealed a ‘core genome’ of 64 genes, the majority of which are also found in other T4‐like phages. Subsequent comparative genomic hybridization analysis using a pilot microarray showed that a number of ‘host’ gene...

Summary Marine cyanobacteria of the genera Prochlorococcus and Synechococcus are important contributors to global primary production occupying a key position at the base of marine food webs. The genetically diverse nature of each genus is likely an important reason for their successful colonization of vast tracts of the world's oceans, a feature that has led to detailed analysis of the distribution of these genetic lineages at...

Summary Marine picocyanobacteria of the genera Prochlorococcus and Synechococcus are major contributors to oceanic primary production. The genera are genetically diverse, comprising several known ecotypes or lineages. However, little is known of the distribution of these lineages over large geographic areas. Here, we analysed the relative abundance of Prochlorococcus ecotypes and Synechococcus lineages at the ocean basin scale...