One-year survey of a single Micronesian reef reveals extraordinarily rich diversity of Symbiodinium types in soritid foraminifera

Recent molecular studies of symbiotic dinoflagellates (genus Symbiodinium) from a wide array of invertebrate hosts have revealed exceptional fine-scale symbiont diversity whose distribution among hosts, regions and environments exhibits significant biogeographic, ecological and evolutionary patterns. Here, similar molecular approaches using the internal transcribed spacer-2 (ITS-2) region were applied to investigate cryptic diversity in Symbiodinium inhabiting soritid foraminifera. Approximately 1,000 soritid specimens were collected and examined during a 12-month period over a 40m depth gradient from a single reef in Guam, Micronesia. Out of 61 ITS-2 types distinguished, 46 were novel. Most types found are specific for soritid hosts, except for three types (C1, C15 and C19) that are common in metazoan hosts. The distribution of these symbionts was compared with the phylotype of their foraminiferal hosts, based on soritid small subunit ribosomal DNA sequences, and three new phylotypes of soritid hosts were identified based on these sequences. Phylogenetic analyses of 645 host-symbiont pairings revealed that most Symbiodinium types associated specifically with a particular foraminiferal host genus or species, and that the genetic diversity of these symbiont types was positively correlated with the genetic diversity found within each of the three host genera. Compared to previous molecular studies of Symbiodinium from other locations worldwide, the diversity reported here is exceptional and suggests that Micronesian coral reefs are home to a remarkably large Symbiodinium assemblag

Limits to the cellular control of sequestered cryptophyte prey in the marine ciliate Mesodinium rubrum

The marine ciliate Mesodinium rubrum is famous for its ability to acquire and exploit chloroplasts and other cell organelles from some cryptophyte algal species. We sequenced genomes and transcriptomes of free-swimming Teleaulax amphioxeia, as well as well-fed and starved M. rubrum in order to understand cellular processes upon sequestration under different prey and light conditions. From its prey, the ciliate acquires the ability to photosynthesize as well as the potential to metabolize several essential compounds including lysine, glycan, and vitamins that elucidate its specific prey dependency. M. rubrum does not express photosynthesis-related genes itself, but elicits considerable transcriptional control of the acquired cryptophyte organelles. This control is limited as light-dependent transcriptional changes found in free-swimming T. amphioxeia got lost after sequestration. We found strong transcriptional rewiring of the cryptophyte nucleus upon sequestration, where 35% of the T. amphioxeia genes were significantly differentially expressed within well-fed M. rubrum. Qualitatively, 68% of all genes expressed within well-fed M. rubrum originated from T. amphioxeia. Quantitatively, these genes contributed up to 48% to the global transcriptome in well-fed M. rubrum and down to 11% in starved M. rubrum. This tertiary endosymbiosis system functions for several weeks, when deprived of prey. After this point in time, the ciliate dies if not supplied with fresh prey cells. M. rubrum represents one evolutionary way of acquiring photosystems from its algal prey, and might represent a step on the evolutionary way towards a permanent tertiary endosymbiosis

Nonlinear Structural Analysis of the Elliptical Dome of the Church in the Universidad Laboral, Gijon, Spain

The Church of the Laboral University of Gijón has the world's largest elliptical masonry roof with 40.8 meters of mayor axis. This big structure is vertically supported with no columns using twenty pairs of masonry ribs crossing each other, and horizontally supported by means of two elliptical ring beams located at the top of the Church. In order to study this historical building, this paper presents the overall three-dimensional structural numerical analysis of the Church, taking into account different material nonlinearities - including masonry and reinforced concrete - as well as geometrical nonlinearities, such as contact effects among the different structural components of the building. Furthermore, a coupled thermal-structural analysis was carried out considering the summer temperature distribution and the Spanish standard rule dead and live loads. The most relevant results, in terms of maximum displacement, stress and, cracking and crushing phenomena are presented. Finally, valuable information from the interaction among the structural elements of the Church are discussed and the most critical points of the building are located, giving place to the most important conclusions of the nonlinear numerical analysis of this interesting structure

Asymmetric Synthesis of Primary and Secondary β-Fluoro-arylamines using Reductive Aminases from Fungi

The synthesis of chiral amines is of central importance to pharmaceutical chemistry, and the inclusion of fluorine atoms in drug molecules can both increase potency and slow metabolism. Optically enriched β-fluoroamines can be obtained by the kinetic resolution of racemic amines using amine transaminases (ATAs), but yields are limited to 50%, and also secondary amines are not accessible. In order to overcome these limitations, we have applied NADPH-dependent reductive aminase enzymes (RedAms) from fungal species to the reductive amination of β-fluoroacetophenones with ammonia, methylamine and allylamine as donors, to yield β-fluoro primary or secondary amines with >90% conversion and between 85 and 99% ee. In addition, the effect of the progressive introduction of fluorine atoms to the β-position of the acetophenone substrate reveals the effect of mono-, di- and tri-fluorination on the proportion of amine and alcohol in product mixtures, shedding light on the promiscuous ability of imine reductase (IRED)-type dehydrogenases to reduce fluorinated acetophenones to alcohols

On the origin and evolution of RNA editing in metazoans

Extensive adenosine-to-inosine (A-to-I) editing of nuclear-transcribed mRNAs is the hallmark of metazoan transcriptional regulation. Here, by profiling the RNA editomes of 22 species that cover major groups of Holozoa, we provide substantial evidence supporting A-to-I mRNA editing as a regulatory innovation originating in the last common ancestor of extant metazoans. This ancient biochemistry process is preserved in most extant metazoan phyla and primarily targets endogenous double-stranded RNA (dsRNA) formed by evolutionarily young repeats. We also find intermolecular pairing of sense-antisense transcripts as an important mechanism for forming dsRNA substrates for A-to-I editing in some but not all lineages. Likewise, recoding editing is rarely shared across lineages but preferentially targets genes involved in neural and cytoskeleton systems in bilaterians. We conclude that metazoan A-to-I editing might first emerge as a safeguard mechanism against repeat-derived dsRNA and was later co-opted into diverse biological processes due to its mutagenic nature

Defining Planktonic Protist Functional Groups on Mechanisms for Energy and Nutrient Acquisition: Incorporation of Diverse Mixotrophic Strategies

Arranging organisms into functional groups aids ecological research by grouping organisms (irrespective of phylogenetic origin) that interact with environmental factors in similar ways. Planktonic protists traditionally have been split between photoautotrophic “phytoplankton” and phagotrophic “microzoo-plankton”. However, there is a growing recognition of the importance of mixotrophy in euphotic aquatic systems, where many protists often combine photoautotrophic and phagotrophic modes of nutrition. Such organisms do not align with the traditional dichotomy of phytoplankton and microzooplankton. To reflect this understanding,we propose a new functional grouping of planktonic protists in an eco- physiological context: (i) phagoheterotrophs lacking phototrophic capacity, (ii) photoautotrophs lacking phagotrophic capacity,(iii) constitutive mixotrophs (CMs) as phagotrophs with an inherent capacity for phototrophy, and (iv) non-constitutive mixotrophs (NCMs) that acquire their phototrophic capacity by ingesting specific (SNCM) or general non-specific (GNCM) prey. For the first time, we incorporate these functional groups within a foodweb structure and show, using model outputs, that there is scope for significant changes in trophic dynamics depending on the protist functional type description. Accord- ingly, to better reflect the role of mixotrophy, we recommend that as important tools for explanatory and predictive research, aquatic food-web and biogeochemical models need to redefine the protist groups within their frameworks