ABSTRACT: Population genomics and connectivity of Vazella pourtalesii sponge grounds of the northwest Atlantic: conservation implications of deep- sea Vulnerable Marine Ecosystems
Project description:To investigate the activity of sponge enhancers in vertebrates transgenic experiments was performed where sponge enhancers were inserted into zebrafish embryos and stable lines generated abstract: Transcription factors (TFs) bind DNA enhancer sequences to regulate gene transcription in animals. Unlike TFs, the evolution of enhancers has been difficult to trace because of their fast evolution. Here, we take enhancers in the sponge Amphimedon queenslandica and test their activity in zebrafish and mouse. Of the five sponge enhancers assessed, three were located in conserved syntenic gene regions that are unique to animals (Islet–Scaper, Ccne1–Uri, Tdrd3–Diaph3). Despite diverging over 700 million years ago and a dearth of sequence identity, sponge enhancers are able to drive cell type-specific reporter gene expression in vertebrates. Analysis of the type and frequency of TF binding motifs in the sponge Islet enhancer allowed for the identification of homologous enhancers in human and mouse, which show remarkably similar reporter expression patterns to the sponge enhancer. These findings uncover an unexpected deep conservation of enhancers and suggest that enhancers established early in metazoan evolution can remain functional through retention of combinations of transcription factor binding motifs despite substantial sequence divergence.
Project description:Tropical lagoon-inhabiting organisms live in highly irradiated ecosystems and are particularly susceptible to thermal stress resulting from climate change. However, despite living close to their thermal maxima, stress response mechanisms found in these organisms are poorly understood. We used a novel physiological-proteomic approach for sponges to describe the stress response mechanisms of the lagoon-inhabiting sponge Amphimedon navalis, when exposed to elevated seawater temperatures of +2 oC and +4 oC relative to a 26 oC ambient temperature for four weeks. After four weeks of thermal exposure, the buoyant weight of the sponge experienced a significant decline, while its pumping rates and oxygen consumption rates significantly increased. Proteome dynamics revealed 50 differentially abundant proteins in sponges exposed to elevated temperature, suggesting that shifts in the sponge proteome were potential drivers of physiological dysfunction. Thermal stress promoted an increase in detoxification proteins, such as catalase and glutathione-S-transferase, suggesting that an excess of reactive oxygen species in sponge cells were likely responsible for the significant increase in oxygen consumption. Elevated temperature also disrupted cellular growth and cell proliferation, promoting the loss of sponge biomass, and the high abundance of multiple alpha-tubulin chain proteins also indicated an increase in cytoskeletal activities within sponge cells, which may have induced the increase in sponge pumping rate. Our results show that sustained thermal exposure in susceptible lagoonal sponges may induce significant disruption of cellular homeostasis leading to physiological dysfunction, and that a combined physiological-proteomic approach may provide new insights into physiological functions and cellular processes occurring in sponges.
Project description:We genotyped 45 new samples from 4 populations of Northwest India and combined it with previously published data to characterize the population structure of modern Northwest Indian populations in the context of their geographic neighbors across South Asia and West Eurasia.
Project description:We are using a minimal model of interacting multispecies ecological communities that incorporates competition, immigration, and demographic noise. Importantly, the dynamics of the system are described by a birth-death process with interactions, whereby the abundance (the number of individuals) of any species is discrete, where the number of individuals from a given species increases or decreases by one following given birth or death rates (respectively).
We find rich behavior with many unexpected regimes. We apply the insights and implications of our model to the range of behaviors observed experimentally in different ecosystems—from bacteria to the immune system.
This repository stores the code used to study the population dynamics described in the PNAS publication: Phenomenology and Dynamics of Competitive Ecosystems Beyond the Niche-Neutral Regimes by Nava Leibovich, Jeremy Rothschild, Sidhartha Goyal and Anton Zilman. See more at (https://github.com/jbRothschild/project-abundance/tree/PNAS)