Synthesis of RNA by dissociated cells of the sea urchin embryo

The Effect of Co-Culture of Two Coral Species on Their Bacterial Composition Under Captive Environments

Coral symbionts are important members of the coral holobiont, and coral bacterial flora are essential in host health maintenance and coral conservation. Coral symbionts are affected by various environmental factors, such as seawater temperature, pH, and salinity. Although physicochemical and chemical factors have been highlighted as possible causes of these effects, the effects of water flow and the co-culture of different species corals have not been elucidated. In this study, we designed an artificial rearing environment to examine the impact of environmental and biological factors on Acropora tenuis, one of the major coral species in Okinawa, and Montipora digitata, during their co-culture. We intervened with the water flow to reveal that the movement of the rearing environment alters the bacterial flora of A. tenuis. During the rearing under captive environment, the alpha diversity of the coral microbiota increased, suggesting the establishment of rare bacteria from the ocean. No differences in the bacterial composition between the control and water flow groups were observed under the rearing conditions. However, the structure of the bacterial flora was significantly different in the co-culture group. Comparison of bacterial community succession strongly suggested that the differences observed were due to the suppressed transmission of bacteria from the ocean in the co-culture group. These results enhance our understanding of interactions between corals and shed light on the importance of regional differences and bacterial composition of coral flora.

Single-cell metabolite detection and genomics reveals uncultivated talented producer

The production of bioactive metabolites is increasingly recognized as an important function of host-associated bacteria. An example is defensive symbiosis that might account for much of the chemical richness of marine invertebrates including sponges (Porifera), 1 of the oldest metazoans. However, most bacterial members of sponge microbiomes have not been cultivated or sequenced, and therefore, remain unrecognized. Unequivocally linking metabolic functions to a cellular source in sponge microbiomes is, therefore, a challenge. Here, we report an analysis pipeline of microfluidic encapsulation, Raman microscopy, and integrated digital genomics (MERMAID) for an efficient identification of uncultivated producers. We applied this method to the chemically rich bacteriosponge (sponge that hosts a rich bacterial community) Theonella swinhoei, previously shown to contain 'Entotheonella' symbionts that produce most of the bioactive substances isolated from the sponge. As an exception, the antifungal aurantosides had remained unassigned to a source. Raman-guided single-bacterial analysis and sequencing revealed a cryptic, distinct multiproducer, 'Candidatus Poriflexus aureus' from a new Chloroflexi lineage as the aurantoside producer. Its exceptionally large genome contains numerous biosynthetic loci and suggested an even higher chemical richness of this sponge than previously appreciated. This study highlights the importance of complementary technologies to uncover microbiome functions, reveals remarkable parallels between distantly related symbionts of the same host, and adds functional support for diverse chemically prolific lineages being present in microbial dark matter.

Metabolic and evolutionary origin of actin-binding polyketides from diverse organisms

Actin-targeting macrolides comprise a large, structurally diverse group of cytotoxins isolated from remarkably dissimilar micro- and macroorganisms. In spite of their disparate origins and structures, many of these compounds bind actin at the same site and exhibit structural relationships reminiscent of modular, combinatorial drug libraries. Here we investigate biosynthesis and evolution of three compound groups: misakinolides, scytophycin-type compounds and luminaolides. For misakinolides from the sponge Theonella swinhoei WA, our data suggest production by an uncultivated 'Entotheonella' symbiont, further supporting the relevance of these bacteria as sources of bioactive polyketides and peptides in sponges. Insights into misakinolide biosynthesis permitted targeted genome mining for other members, providing a cyanobacterial luminaolide producer as the first cultivated source for this dimeric compound family. The data indicate that this polyketide family is bacteria-derived and that the unusual macrolide diversity is the result of combinatorial pathway modularity for some compounds and of convergent evolution for others.

Membrane fractions display different lipid and enzyme content in three cell types in 16-cell stage embryos of sea urchins

Three cell types were isolated from dissociated 16-cell sea urchin embryos. Four membrane density fractions from discontinuous gradients have different proportions of lipids, surfacer markers and enzymes for the three cell types. Assays of lipid content, CH/PLIPID and SPH/PC ratios, acyl chain length, level of unsaturation by proton NMR and assays of enzyme activity revealed variation at the same density between the three cell types and among different densities from one cell type. There were also differences between whole embryos and dissociated embryo cells. There was no typical membrane domain at a particular density common to the cell types. Cell surface characteristics and polarity of adult cells rely on which lipid domains and enzymes are present, their association with cytoskeleton and how they are localized. At the 16-cell stage these characteristics are still very dynamic as revealed by cytochemical localization of Na+/K(+)-ATPase which varied with cell type and suggests endocytosis at set times in the division cycle. Polarity has not been permanently set for Na+/K(+)-ATPase yet. Membrane enzyme and lipid distributions unique to the three cell types seen in this study suggest parcelling out or insertion of new membrane domains occurs during early sea urchin cleavage. Perturbation of membrane density distribution and lipid content occurs after treatment of embryos with animalizing and vegetalizing teratogens which alter development.

Composition of the nucleotides pool in a morphogenetic compartment in eggs of Nassarius reticulatus (Mollusca) analysed by capillary isotachophoresis

The spectrum of low molecular weight compounds, in particular of ribonucleotides, within first cleavage stage embryos of the polar lobe-forming mollusc Nassarius reticulatus and the distribution of the compounds within the embryo at the trefoil stage of first cleavage are analysed by means of capillary isotachophoresis after 0.5 M PCA extraction. The compounds which are found in the whole trefoil embryo (T), the lobeless part (LL), and the polar lobe (PL) respectively, and the mean quantities (nmol. microliter-1; n = 6) are: UTP (11.5, 4.8, 5.6), ITP (8.5, 3.6, 5.0), GTP (10.3, 3.0, 9.0), ATP (29.8, 13.4, 18.8), UDP (11.8, 3.4, 8.7), CTP (8.0, 3.1, 4.5), GDP (5.3, 2.6, 3.4), ADP (16.5, 6.1, 11.6), CDP (4.0, 1.4, 2.6), GMP (4.7, 2.7, 4.3), glucose-6-phosphate (G6P) (53.5, 38.8, 13.0). These compounds appear to be localized in the non-yolk cytoplasmic pool. As the volume ratio of PL/LL for total volume and for non-yolk cytoplasmic volume is about 0.74 and 0.60 respectively, the concentration of all nucleotides in PL as compared to LL is significantly higher (HO, p less than 0.001), both relative to the total volume and to the non-yolk cytoplasmic volume. The G6P concentration is considerably higher in the lobeless part. The morphogenetic role of the vegetal pole compartment of the egg apparently is correlated with a relatively high level of its nucleotide contents.

Mass isolation and culture of sea urchin micromeres

A procedure is described for large-scale isolation of micromeres from 16-cell stage sea urchin embryos. One to two grams of greater than 99% pure, viable micromeres (2.3 to 4.6 X 10(8) cells) are routinely isolated in a single preparation. In culture, these cells uniformly proceed through their normal development, in synchrony with micromeres in whole embryos, ultimately differentiating typical larval skeletal structures. The attributes of this procedure are: (a) the very early time of isolation of the cells, directly after the division that establishes the cell line; (b) the large yield of cells; (c) the purity of the preparation of cell; and (d) their synchronous development in culture through skeletogenesis. The procedure greatly aids in making sea urchin micromeres a favorable material for molecular analysis of development.

Chemical messengers in development: a hypothesis

The hypothesis that physiological and developmental regulatory mechanisms are similar has been presented. Well-known developmental systems chosen illustrate the capability of the model to suggest a simple mechanism underlying the effects on development of a diverse group of chemicals. This hypothesis might be applied to other systems including the induction of the lens, limb regeneration, and the induction of the head of hydra (124). I have proposed this hypothesis not only because it permits consideration of a complex and varied array of experimental observations as reflections of a simple basic biochemical mechanism, but because recent technical advances in instrumentation and methods allow it to be directly tested. The fluorescent antibody method for the cytochemical measurement of cyclic nucleotides provides a means for investigating changes in the concentrations of cyclic nucleotides in developing cells and could also be used to detect neurotransmitters in developing cells. Similarly, the scanning electron microscope in the emitted x-ray mode provides a method for measuring changes in the content and distribution of cations within developing cells. The hypothesis presented here suggests pleasing asceticism on the part of eukaryotes. It suggests that simple derivatives of metabolites, including neurotransmitters and cyclic nucleotides, are linked together as regulatory molecules throughout the eukaryotes. The neurotransmitters are suggested to have a more general role in information transmission in eukaryotes than is generally accepted. They are hypothesized to have progressed during evolution from being intracellular messengers to a role as intercellular messengers for the relatively slow communication of developmental informatbn; and, finally, this process has culminated with their participation in the rapid intercellular communication mediated by nerves. The thought that the complex pictures of physiological regulation and of the construction of a complex multicellular organism like man might be painted with so few colors is quite satisfying.