Microbial communities in developmental stages of lucinid bivalves.

Bivalves from the family Lucinidae host sulfur-oxidizing bacterial symbionts, which are housed inside specialized gill epithelial cells and are assumed to be acquired from the environment. However, little is known about the Lucinidae life cycle and symbiont acquisition in the wild. Some lucinid species broadcast their gametes into the surrounding water column, however, a few have been found to externally brood their offspring by the forming gelatinous egg masses. So far, symbiont transmission has only been investigated in one species that reproduces via broadcast spawning. Here, we show that the lucinid Loripes orbiculatus from the West African coast forms egg masses and these are dominated by diverse members of the Alphaproteobacteria, Clostridia, and Gammaproteobacteria. The microbial communities of the egg masses were distinct from those in the environments surrounding lucinids, indicating that larvae may shape their associated microbiomes. The gill symbiont of the adults was undetectable in the developmental stages, supporting horizontal transmission of the symbiont with environmental symbiont acquisition after hatching from the egg masses. These results demonstrate that L. orbiculatus acquires symbionts from the environment independent of the host's reproductive strategy (brooding or broadcast spawning) and reveal previously unknown associations with microbes during lucinid early development.

Correction: Host and environmental determinants of microbial community structure in the marine phyllosphere.

[This corrects the article DOI: 10.1371/journal.pone.0235441.].

Composition of seagrass phyllosphere microbial communities suggests rapid environmental regulation of community structure.

Recent studies have revealed that seagrass blade surfaces, also known as the phyllosphere, are rich habitats for microbes; however, the primary drivers of composition and structure in these microbial communities are largely unknown. This study utilized a reciprocal transplant approach between two sites with different environmental conditions combined with 16S rRNA gene sequencing (iTag) to examine the relative influence of environmental conditions and host plant on phyllosphere community composition of the seagrass Thalassia testudinum. After 30 days, identity of phyllosphere microbial community members was more similar within the transplant sites than between despite differences in the source of host plant. Additionally, the diversity and evenness of these communities was significantly different between the two sites. These results indicated that local environmental conditions can be a primary driver in structuring seagrass phyllosphere microbial communities over relatively short time scales. Composition of microbial community members in this study also deviated from those in previous seagrass phyllosphere studies with a higher representation of candidate bacterial phyla and archaea than previously observed. The capacity for seagrass phyllosphere microbial communities to shift dramatically with environmental conditions, including ecosystem perturbations, could significantly affect seagrass-microbe interactions in ways that may influence the health of the seagrass host.

Host and environmental determinants of microbial community structure in the marine phyllosphere.

Although seagrasses are economically and ecologically critical species, little is known about their blade surface microbial communities and how these communities relate to the plant host. To determine microbial community composition and diversity on seagrass blade surfaces and in the surrounding seawater,16S rRNA gene sequencing (iTag) was used for samples collected at five sites along a gradient of freshwater input in the northern Gulf of Mexico on three separate sampling dates. Additionally, seagrass surveys were performed and environmental parameters were measured to characterize host characteristics and the abiotic conditions at each site. Results showed that Thalassia testudinum (turtle grass) blades hosted unique microbial communities that were distinct in composition and diversity from the water column. Environmental conditions, including water depth, salinity, and temperature, influenced community structure as blade surface microbial communities varied among sites and sampling dates in correlation with changes in environmental parameters. Microbial community composition also correlated with seagrass host characteristics, including growth rates and blade nutrient composition. There is some evidence for a core community for T. testudinum as 21 microorganisms from five phyla (Cyanobacteria, Proteobacteria, Planctomycetes, Chloroflexi, and Bacteroidetes) were present in all blade surface samples. This study provides new insights and understanding of the processes that influence the structure of marine phyllosphere communities, how these microbial communities relate to their host, and their role as a part of the seagrass holobiont, which is an important contribution given the current decline of seagrass coverage worldwide.

Building biases in infancy: the influence of race on face and voice emotion matching.

Early in the first year of life infants exhibit equivalent performance distinguishing among people within their own race and within other races. However, with development and experience, their face recognition skills become tuned to groups of people they interact with the most. This developmental tuning is hypothesized to be the origin of adult face processing biases including the other-race bias. In adults the other-race bias has also been associated with impairments in facial emotion processing for other-race faces. The present investigation aimed to show perceptual narrowing for other-race faces during infancy and to determine whether the race of a face influences infants' ability to match emotional sounds with emotional facial expressions. Behavioral (visual-paired comparison; VPC) and electrophysiological (event-related potentials; ERPs) measures were recorded in 5-month-old and 9-month-old infants. Behaviorally, 5-month-olds distinguished faces within their own race and within another race, whereas 9-month-olds only distinguish faces within their own race. ERPs were recorded while an emotion sound (laughing or crying) was presented prior to viewing an image of a static African American or Caucasian face expressing either a happy or a sad emotion. Consistent with behavioral findings, ERPs revealed race-specific perceptual processing of faces and emotion/sound face congruency at 9 months but not 5 months of age. In addition, from 5 to 9 months, the neural networks activated for sound/face congruency were found to shift from an anterior ERP component (Nc) related to attention to posterior ERP components (N290, P400) related to perception.