The entomopathogenic bacterial endosymbionts Xenorhabdus and Photorhabdus: convergent lifestyles from divergent genomes.

Members of the genus Xenorhabdus are entomopathogenic bacteria that associate with nematodes. The nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. The nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal.

The genome sequence of the leaf-cutter ant Atta cephalotes reveals insights into its obligate symbiotic lifestyle.

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies.

An insect herbivore microbiome with high plant biomass-degrading capacity.

Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity.

Genome sequences of three agrobacterium biovars help elucidate the evolution of multichromosome genomes in bacteria.

The family Rhizobiaceae contains plant-associated bacteria with critical roles in ecology and agriculture. Within this family, many Rhizobium and Sinorhizobium strains are nitrogen-fixing plant mutualists, while many strains designated as Agrobacterium are plant pathogens. These contrasting lifestyles are primarily dependent on the transmissible plasmids each strain harbors.

The effect of chromosome geometry on genetic diversity.

Although organisms with linear chromosomes must solve the problem of fully replicating their chromosome ends, this chromosome configuration has emerged repeatedly during bacterial evolution and is evident in three divergent bacterial phyla. The benefit usually ascribed to this topology is the ability to boost genetic variation through increased recombination. But because numerous processes can impact linkage disequilibrium, such an effect is difficult to assess by comparing across bacterial taxa that possess different chromosome topologies.

Biochemical limitations to high-level expression of humanized monoclonal antibodies in transgenic maize seed endosperm.

Transgenic plants are potentially valuable systems for the large scale manufacture of therapeutic proteins. To improve this technology, determining the importance of transgene transcript levels on protein accumulation in sink tissues during their development is crucial. In transgenic maize (Zea mays L.

Application of the Synechococcus nirA promoter to establish an inducible expression system for engineering the Synechocystis tocopherol pathway.

Tocopherols are important antioxidants in lipophilic environments. They are synthesized by plants and some photosynthetic bacteria. Recent efforts to analyze and engineer tocopherol biosynthesis led to the identification of Synechocystis sp.

Global mutational analysis of NtrC-like activators in Myxococcus xanthus: identifying activator mutants defective for motility and fruiting body development.

The multicellular developmental cycle of Myxococcus xanthus requires large-scale changes in gene transcription, and recent findings indicate that NtrC-like activators play a prominent role in regulating these changes. In this study, we made insertions in 28 uncharacterized ntrC-like activator (nla) genes and found that eight of these insertions cause developmental defects. Hence, these results are consistent with the idea that M.