Biology subjects

Carlson, D. E.

Publications and source records attributed to Carlson, D. E..

3 recordsLinked to original sources

bioRxiv2020

The relationship between microbiomes and selective regimes in the sponge genus Ircinia.

Sponges are often densely populated by microbes that benefit their hosts through nutrition and bioactive secondary metabolites; however, sponges must simultaneously contend with the toxicity of microbes and thwart microbial overgrowth. Despite these fundamental tenets of sponge biology, the patterns of selection in the host sponges genomes that underlie tolerance and control of their microbiomes are still poorly understood. To elucidate these patterns of selection, we performed a population genetic analysis on multiple species of Ircinia from Belize, Florida, and Panama using an FST-outlier approach on transcriptome-annotated RADseq loci. As part of the analysis, we delimited species boundaries among seven growth forms of Ircinia. Our analyses identified balancing selection in immunity genes that have implications for the hosts tolerance of high densities of microbes. Additionally, our results support the hypothesis that each of the seven growth forms constitutes a distinct Ircinia species that is characterized by a unique microbiome. These results illuminate the evolutionary pathways that promote stable associations between host sponges and their microbiomes, and that potentially facilitate ecological divergence among Ircinia species.

evolutionary biology↗

bioRxiv2020

Comparative metagenomics evidence distinct evolutionary trends of genome evolution in sponge-dwelling bacteria and their pelagic counterparts

Prokaryotic associations with sponges are among the oldest host-microbiome relationships on Earth. In this study, we investigated how bacteria from several phyla have independently adapted to the sponge interior by comparing metagenome-assembled genomes of sponge-dwelling and pelagic bacteria sourced from broad phylogenetic and geographic samplings. We discovered that sponge-dwelling bacteria have more energetically expensive genomes and share patterns of depletion and enrichment for functional categories of genes that evidence evolution towards lower pathogenicity. We also identified a new defining genomic characteristic of sponge-dwelling bacteria that is virtually absent from pelagic bacteria, the presence of cassettes that contain eukaryotic steroid biosynthesis genes. Collectively, these results illuminate the trends in genome evolution that are associated with a sponge-dwelling life history strategy and have implications for furthering our understanding of how sponge-microbial symbioses have persisted through deep evolutionary time. ImportanceMuch attention has recently been devoted to investigating the evolution of microbes that live in symbiosis with sponge hosts using microbial metagenomic data. However, several biological questions regarding this symbiosis remain unanswered. Two questions that we address here are: 1) what are the long-term consequences of the symbiosis on the evolution of microbial symbiont genome size, protein content, and nucleotide content, and 2) how is the evolution of virulence in sponge-dwelling microbial symbionts, which generally undergo a mixed transmission modes (e.g. horizontal and vertical), related to long-term stability of the symbiosis? By employing the largest comparative metagenomic analysis to date in terms of host sponge species and geographic representation, we address these questions and provide further resolution into the evolutionary processes that are involved in mediating the crosstalk between sponge hosts and their microbial symbionts.

genomics↗

bioRxiv2020

Brain-wide electrical dynamics encode an appetitive socioemotional state

Many cortical and subcortical regions contribute to complex social behavior; nevertheless, the network level architecture whereby the brain integrates this information to encode appetitive socioemotional behavior remains unknown. Here we measure electrical activity from eight brain regions as mice engage in a social preference assay. We then use machine learning to discover an explainable brain network that encodes the extent to which mice chose to engage another mouse. This socioemotional network is organized by theta oscillations leading from prelimbic cortex and amygdala that converge on ventral tegmental area, and network activity is synchronized with brain-wide cellular firing. The network generalizes, on a mouse-by-mouse basis, to encode socioemotional behaviors in healthy animals, but fails to encode an appetitive socioemotional state in a high confidence genetic mouse model of autism. Thus, our findings reveal the architecture whereby the brain integrates spatially distributed activity across timescales to encode an appetitive socioemotional brain state in health and disease.

neuroscience↗