Molecular evolution of calcification genes in morphologically similar but phylogenetically unrelated scleractinian corals

Seasonal Proteome Variations in Orbicella faveolata Reveal Molecular Thermal Stress Adaptations

Although seasonal water temperatures typically fluctuate by less than 4 °C across most tropical reefs, sustained heat stress with an increase of even 1 °C can alter and destabilize metabolic and physiological coral functions, leading to losses of coral reefs worldwide. The Caribbean region provides a natural experimental design to study how corals respond physiologically throughout the year. While characterized by warm temperatures and precipitation, there is a significant seasonal component with relative cooler and drier conditions during the months of January to February and warmer and wetter conditions during September and October. We conducted a comparative abundance of differentially expressed proteins with two contrasting temperatures during the cold and warm seasons of 2014 and 2015 in Orbicella faveolata, one of the most important and affected reef-building corals of the Caribbean. All presented proteoforms (42) were found to be significant in our proteomics differential expression analysis and classified based on their gene ontology. The results were accomplished by a combination of two-dimensional gel electrophoresis (2DE) to separate and visualize proteins and mass spectrometry (MS) for protein identification. To validate the differentially expressed proteins of Orbicella faveolata at the transcription level, qRT-PCR was performed. Our data indicated that a 3.1 °C increase in temperature in O. faveolata between the cold and warm seasons in San Cristobal and Enrique reefs of southwestern Puerto Rico was enough to affect the expression of a significant number of proteins associated with oxidative and heat stress responses, metabolism, immunity, and apoptosis. This research extends our knowledge into the mechanistic response of O. faveolata to mitigate thermal seasonal temperature variations in coral reefs.

How corals made rocks through the ages

Hard, or stony, corals make rocks that can, on geological time scales, lead to the formation of massive reefs in shallow tropical and subtropical seas. In both historical and contemporary oceans, reef-building corals retain information about the marine environment in their skeletons, which is an organic-inorganic composite material. The elemental and isotopic composition of their skeletons is frequently used to reconstruct the environmental history of Earth's oceans over time, including temperature, pH, and salinity. Interpretation of this information requires knowledge of how the organisms formed their skeletons. The basic mechanism of formation of calcium carbonate skeleton in stony corals has been studied for decades. While some researchers consider coral skeletons as mainly passive recorders of ocean conditions, it has become increasingly clear that biological processes play key roles in the biomineralization mechanism. Understanding the role of the animal in living stony coral biomineralization and how it evolved has profound implications for interpreting environmental signatures in fossil corals to understand past ocean conditions. Here we review historical hypotheses and discuss the present understanding of how corals evolved and how their skeletons changed over geological time. We specifically explain how biological processes, particularly those occurring at the subcellular level, critically control the formation of calcium carbonate structures. We examine the different models that address the current debate including the tissue-skeleton interface, skeletal organic matrix, and biomineralization pathways. Finally, we consider how understanding the biological control of coral biomineralization is critical to informing future models of coral vulnerability to inevitable global change, particularly increasing ocean acidification.

Montastraea cavernosa corallite structure demonstrates distinct morphotypes across shallow and mesophotic depth zones in the Gulf of Mexico

This study assessed morphological variation of the depth-generalist coral Montastraea cavernosa across shallow and mesophotic coral ecosystems in the Gulf of Mexico (GOM) using thirteen corallite metrics. While corallite structure differed significantly across sites, we observed that mean corallite diameters were smaller and spacing was greater in mesophotic corals as compared to shallow corals. Additional corallite variation, including greater mean corallite height of mesophotic samples, are hypothesized to be photoadaptive responses to low light environments. Multivariate analyses also revealed two distinct morphotypes identified by significant variation in corallite spacing with >90% accuracy. A 'shallow' morphotype was characterized by larger, more closely-spaced corallites, while a 'depth-generalist' type exhibited smaller, further-spaced corallites. Variable presence of morphotypes within some sites suggests genotypic influence on corallite morphology as there was a slight, but significant, impact of morphotype on genetic structure within shallow zones in the Flower Garden Banks. Patterns of increased algal symbiont (Symbiodiniaceae) density and chlorophyll concentration were retained in the depth-generalist morphotype even in shallow zones, identifying multiple photoadaptive strategies between morphotypes. The results of this study suggest that morphological variation among M. cavernosa represents a combination of genotypic variation and phenotypic plasticity rather than responses to environmental stimuli alone.

Medicinal Purposes: Bioactive Metabolites from Marine-derived Organisms

The environment of marine occupies about 95% biosphere of the world and it can be a critical source of bioactive compounds for humans to be explored. Special environment such as high salt, high pressure, low temperature, low nutrition and no light, etc. has made the production of bioactive substances different from terrestrial organisms. Natural ingredients secreted by marine-derived bacteria, fungi, actinomycetes, Cyanobacteria and other organisms have been separated as active pharmacophore. A number of evidences have demonstrated that bioactive ingredients isolated from marine organisms can be other means to discover novel medicines, since enormous natural compounds from marine environment were specified to be anticancer, antibacterial, antifungal, antitumor, cytotoxic, cytostatic, anti-inflammatory, antiviral agents, etc. Although considerable progress is being made within the field of chemical synthesis and engineering biosynthesis of bioactive compounds, marine environment still remains the richest and the most diverse sources for new drugs. This paper reviewed the natural compounds discovered recently from metabolites of marine organisms, which possess distinct chemical structures that may form the basis for the synthesis of new drugs to combat resistant pathogens of human life. With developing sciences and technologies, marine-derived bioactive compounds are still being found, showing the hope of solving the problems of human survival and sustainable development of resources and environment.

Carbonic Anhydrases in Cnidarians: Novel Perspectives from the Octocorallian Corallium rubrum

Although the ability to elaborate calcium carbonate biominerals was apparently gained independently during animal evolution, members of the alpha carbonic anhydrases (α-CAs) family, which catalyze the interconversion of CO2 into HCO3-, are involved in the biomineralization process across metazoans. In the Mediterranean red coral Corallium rubrum, inhibition studies suggest an essential role of CAs in the synthesis of two biominerals produced in this octocoral, the axial skeleton and the sclerites. Hitherto no molecular characterization of these enzymes was available. In the present study we determined the complete set of α-CAs in C. rubrum by data mining the genome and transcriptome, and measured their differential gene expression between calcifying and non-calcifying tissues. We identified six isozymes (CruCA1-6), one cytosolic and five secreted/membrane-bound among which one lacked two of the three zinc-binding histidines and was so referred to as a carbonic anhydrase related protein (CARP). One secreted isozyme (CruCA4) showed specific expression both by qPCR and western-blot in the calcifying tissues, suggesting its involvement in biomineralization. Moreover, phylogenetic analyses of α-CAs, identified in six representative cnidarians with complete genome, support an independent recruitment of α-CAs for biomineralization within anthozoans. Finally, characterization of cnidarian CARPs highlighted two families: the monophyletic cytosolic CARPs, and the polyphyletic secreted CARPs harboring a cnidarian specific cysteine disulfide bridge. Alignment of the cytosolic CARPs revealed an evolutionary conserved R-H-Q motif in place of the characteristic zinc-binding H-H-H necessary for the catalytic function of α-CAs.

Proteomic analysis of bleached and unbleached Acropora palmata, a threatened coral species of the Caribbean

There has been an increase in the scale and frequency of coral bleaching around the world due mainly to changes in sea temperature. This may occur at large scales, often resulting in significant decline in coral coverage. In order to understand the molecular and cellular basis of the ever-increasing incidence of coral bleaching, we have undertaken a comparative proteomic approach with the endangered Caribbean coral Acropora palmata. Using a proteomic tandem mass spectrometry approach, we identified 285 and 321 expressed protein signatures in bleached and unbleached A. palmata colonies, respectively, in southwestern Puerto Rico. Overall the expression level of 38 key proteins was significantly different between bleached and unbleached corals. A wide range of proteins was detected and categorized, including transcription factors involved mainly in heat stress/UV responses, immunity, apoptosis, biomineralization, the cytoskeleton, and endo-exophagocytosis. The results suggest that for bleached A. palmata, there was an induced differential protein expression response compared with those colonies that did not bleach under the same environmental conditions.

The phylogenetic diversity of Spirometra erinaceieuropaei isolates from southwest China revealed by multi genes

The larval plerocercoid of Spirometra erinaceieuropaei can parasitize humans, causing a serious food borne parasitic zoonosis known as sparganosis. Sparganosis have increased in China in recent years. In this study, the prevalence of sparganum infection in wild frogs in 9 geographical areas in southwest China was firstly investigated. Of 276 caught frogs, 55 frogs were found to be infected with sparganum. Then, the population genetic structure of these sparganum isolates was explored based on four molecular markers (cytb, cox1, rrnS and 28S rDNA D1). Highly genetic diversity and the genetic differentiation among sparganum isolates from different sites were revealed in the DNA polymorphism analyses. Both the phylogenetic inference and the analysis of the median-joining network supported two clades in the southwest S. erinaceieuropaei population. However, none demographic population expansion of the southwest S. erinaceieuropaei population was observed in the neutrality test, mismatch distribution analysis and Bayesian skyline plot analysis. Finally, the phylogenetic diversity of S. erinaceieuropaei from eastern, central, southern and southwest China was analyzed, the result suggested that Chinese S. erinaceieuropaei population should be divided into two groups (Group I and Group II), and they started to divergence in the middle Pliocene.