Azospirillum Genomes Reveal Transition of Bacteria from Aquatic to Terrestrial Environments

Fossil records indicate that life appeared in marine environments ∼3.5 billion years ago (Gyr) and transitioned to terrestrial ecosystems nearly 2.5 Gyr. Sequence analysis suggests that “hydrobacteria” and “terrabacteria” might have diverged as early as 3 Gyr. Bacteria of the genus Azospirillum are associated with roots of terrestrial plants; however, virtually all their close relatives are aquatic. We obtained genome sequences of two Azospirillum species and analyzed their gene origins. While most Azospirillum house-keeping genes have orthologs in its close aquatic relatives, this lineage has obtained nearly half of its genome from terrestrial organisms. The majority of genes encoding functions critical for association with plants are among horizontally transferred genes. Our results show that transition of some aquatic bacteria to terrestrial habitats occurred much later than the suggested initial divergence of hydro- and terrabacterial clades. The birth of the genus Azospirillum approximately coincided with the emergence of vascular plants on land

From Sea to Sea: Canada's Three Oceans of Biodiversity

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage

Enucleation and Techniques of Orbital Implant Placement

Enucleation is a surgical procedure that involves removal of the eye and anterior optic nerve, most commonly with retention of the extraocular muscles which are then sewn to the implant. Meticulous surgical technique is essential to prevent long-term complications and ensure optimal long-term function and cosmesis of the anophthalmic socket. When appropriate surgical technique is used, the patient often has a significant improvement in both function and cosmesis after an enucleation, and is quite grateful for the relief of pain they can achieve. It is critical that the surgeon approach this surgery keeping the long term view of the anophthalmic socket in mind. Generally, this involves providing the patient with the largest implant that will fit the socket without undue tension during Tenon’s capsule and conjunctival closure, thereby minimizing socket and eyelid asymmetry and preventing future forniceal and eyelid issues. This chapter reviews basics of enucleation surgery, with a focus on methods to achieve optimal results. Also, the chapter discusses implant placement techniques and provides a brief review of enucleation implants. Additionally, it describes how enucleation implants have evolved and improved over time

Role for Rhizobium rhizogenes K84 Cell Envelope Polysaccharides in Surface Interactions

Rhizobium rhizogenes strain K84 is a commercial biocontrol agent used worldwide to control crown gall disease. The organism binds tightly to polypropylene substrate and efficiently colonizes root surfaces as complex, multilayered biofilms. A genetic screen identified two mutants in which these surface interactions were affected. One of these mutants failed to attach and form biofilms on the abiotic surface although, interestingly, it exhibited normal biofilm formation on the biological root tip surface. This mutant is disrupted in a wcbD ortholog gene, which is part of a large locus predicted to encode functions for the biosynthesis and export of a group II capsular polysaccharide (CPS). Expression of a functional copy of wcbD in the mutant background restored the ability of the bacteria to attach and form normal biofilms on the abiotic surface. The second identified mutant attached and formed visibly denser biofilms on both abiotic and root tip surfaces. This mutant is disrupted in the rkpK gene, which is predicted to encode a UDP-glucose 6-dehydrogenase required for O-antigen lipopolysaccharide (LPS) and K-antigen capsular polysaccharide (KPS) biosynthesis in rhizobia. The rkpK mutant from strain K84 was deficient in O-antigen synthesis and exclusively produced rough LPS. We also show that strain K84 does not synthesize the KPS typical of some other rhizobia strains. In addition, we identified a putative type II CPS, distinct from KPS, that mediates cell-surface interactions, and we show that O antigen of strain K84 is necessary for normal cell-cell interactions in the biofilms