In this paper we describe the gut microbiome of the Puerto Rican keystone sea urchin Diadema antillarum. We also used next generation sequencing of the cytochrome b region to examine the phylogenetic relationships among ...

The increased of Antibiotic Resistance (AR) is currently one of the most important public health threats faced worldwide. Increasing rates on AR has been observed globally. The use and analysis of non-traditional techniques ...

The microbiota, the set of microorganisms associated with a particular environment or host, has acquired a prominent role in the study of many physiological and developmental processes. Here I explore a possible role of the microbiota in regeneration, focusing primarily on the regeneration of the intestine in the sea cucumber Holothuria glaberrima, an echinoderm common in local waters. In CHAPTER 1, I review the involvement of the microbiota in regeneration-related cellular events, providing examples of regenerative models that extend from the repair of tissue layers to the regeneration of complete organs or animals. In addition, I highlight the role of the microbiota in the digestive tract, in echinoderms, primarily holothuroids, which are models for regeneration studies. As a first step in these studies, I characterize the microbiota of normal and regenerating animals (CHAPTER 2). In this chapter the microbial community of sea cucumbers undergoing intestinal regeneration was studied using 16S rRNA amplicon sequencing. For this, sea cucumbers were eviscerated and left to regenerate in seawater aquaria for up to 21 days. Among the findings reported are: (i) the existence of microbial compartmentalization in normal animals which changes in regenerating animals. (ii) a strong effect of the environment, in this case the closed aquarium system, on the normal and regenerating microbiota, (iii)) an increase in species richness and evenness in regenerating animals and (iv) differential abundance of specific bacterial taxa. To determine the role of the microbiota in the regeneration process an initial approach was executed in the following chapters. CHAPTER 3, shows the experiments where the effects of various antibiotics on intestinal regeneration of H. glaberrima were evaluated. For this, eviscerated holothurians were exposed to different antibiotic cocktails and left to regenerate for 10 days. Immunohistological and histochemical analyses were performed to analyze regenerative processes, including rudiment size, extracellular matrix (ECM) remodeling, cell proliferation, and muscle dedifferentiation. Reduction in muscle dedifferentiation, ECM remodeling, and the size of their regenerating rudiments were observed in antibiotic-treated animals in comparison to untreated ones. Our results demonstrate a negative effect of antibiotics on intestinal regeneration and strongly suggest that these effects are due to alterations in the microbial community. To discard the possibility that the antibiotics directly affect holothurian metabolic activity, their effect on the metabolism of H. glaberrima tissues was assayed. A second approach to test the effect of microbiota on intestinal regeneration is shown on CHAPTER 4. Here I utilized fecal microbial transplants (FMT) to validate the effectiveness of microbial transplants in enhancing intestinal regeneration. For this, eviscerated holothuroids, exposed to antibiotics prior to evisceration, were subjected to FMT from non-eviscerated donors. Control animals received no FMT or autoclaved FMT. Bacterial samples were cultured from each group to verify if antibiotics could induce changes in the animal microbiota. Histological analysis revealed that different combinations of antibiotics, along with FMT, have specific effects on various regeneration processes. These findings support the role of the microbiota in the sea cucumber's intestinal regeneration process, reveal factors contributing to organ regeneration, and provide insight into little studied functions of the gut microbiota....