The association of phytoplankton with bacteria is ubiquitous in nature and the bacteria that associate with different phytoplankton species are very diverse. The influence of these bacteria in the physiology and ecology of the host and the evolutionary forces that shape the relationship are still not understood. In this study, we used the Pseudo-nitzschia-microbiota association to determine (1) if algal species with distinct domoic acid (DA) production are selection factors that structures the bacterial community, (2) if host-specificity and co-adaptation govern the association, (3) the functional roles of isolated member of microbiota on diatom-hosts fitness and (4) the influence of microbiota in changing the phenotype of the diatom hosts with regards to toxin production. Analysis of the pyrosequencing-derived 16S rDNA data suggests that the three tested species of Pseudo-nitzschia, which vary in toxin production, have phylogenetically distinct bacterial communities, and toxic Pseudo-nitzschia have lower microbial diversity than non-toxic Pseudonitzschia. Transplant experiments showed that isolated members of the microbiota are mutualistic to their native hosts but some are commensal or parasitic to foreign hosts, hinting at co-evolution between partners. Moreover, Pseudo-nitzschia host can gain protection from algalytic bacteria by maintaining association with its microbiota. Pseudo-nitzschia also exhibit different phenotypic expression with regards to DA production, and this depends on the bacterial species with which the host associates. Hence, the influences of the microbiota on diatom host physiology should be considered when studying the biology and ecology of marine diatoms.

A 2-year-old male pediatric patient experienced a partial occlusion of the internal carotid and subsequent asphyxiation resulting in hypoxic brain injury that was later misdiagnosed as primary attention deficient hyperactivity disorder (ADHD). Imaging analyses using diffusion tensor imaging (DTI), positron emission tomography (PET), and magnetic resonance imaging (MRI) quantitative volumetrics (QV) were used nine years following the incident to identify whether his development of ADHD is of a primary heritability or secondary hypoxic brain injury sequelae. The patient's DTI analysis generated decreases in fractional anisotropy (FA) values in the anterior corpus callosum, bilateral internal capsule, and hippocampus. Decreases in FA are seen in ADHD patients, but the degree of FA decrease in the patient under study is several orders of magnitude greater than in ADHD patients. Also, not normally observed in ADHD patients were decreases in the metabolism of the orbitofrontal cortex, anterior cingulate, left anterior insular cortex, and left striatum. Additionally, QV showed enlargements of various regions of the brain including the amygdala which is often cited in the literature to be reduced in ADHD patients. The diagnosis of this patient despite having non-characteristic neuroimaging data suggests a unique specificity of the hypoxic injury to the development of a secondary hypoxic brain injury caused ADHD.