Coverage,Diversity, and Functionality of a High-Latitude Coral Community (Tatsukushi,Shikoku Island,Japan)

Background

Seawater temperature is the main factor restricting shallow-water zooxanthellate coral reefs to low latitudes. As temperatures increase, coral species and perhaps reefs may move into higher-latitude waters, increasing the chances of coral reef ecosystems surviving despite global warming. However, there is a growing need to understand the structure of these high-latitude coral communities in order to analyze their future dynamics and to detect any potential changes.

Methodology/Principal Findings

The high-latitude (32.75°N) community surveyed was located at Tatsukushi, Shikoku Island, Japan. Coral cover was 60±2% and was composed of 73 scleractinian species partitioned into 7 functional groups. Although only 6% of species belonged to the ‘plate-like’ functional group, it was the major contributor to species coverage. This was explained by the dominance of plate-like species such as Acropora hyacinthus and A. solitaryensis. Comparison with historical data suggests a relatively recent colonization/development of A. hyacinthus in this region and a potential increase in coral diversity over the last century. Low coverage of macroalgae (2% of the benthic cover) contrasted with the low abundance of herbivorous fishes, but may be reasonably explained by the high density of sea urchins (12.9±3.3 individuals m⁻²).

Conclusions/Significance

The structure and composition of this benthic community are relatively remarkable for a site where winter temperature can durably fall below the accepted limit for coral reef development. Despite limited functionalities and functional redundancy, the current benthic structure might provide a base upon which a reef could eventually develop, as characterized by opportunistic and pioneer frame-building species. In addition to increasing seawater temperatures, on-going management actions and sea urchin density might also explain the observed state of this community. A focus on such ‘marginal’ communities should be a priority, as they can provide important insights into how tropical corals might cope with environmental changes.     

Overexpression of the CT GalNAc transferase inhibits muscular dystrophy in a cleavage-resistant dystroglycan mutant mouse

Transgenic mice that express dystroglycan containing a serine to alanine point mutation at the normal site of cleavage (DG(S654A)) in their skeletal muscles fail to express endogenously cleaved dystroglycan and have muscular dystrophy [Neuromusc. Disord., in press]. Dystrophic DG(S654A) muscles have reduced binding of antibodies, including VIA4-1, that recognize carbohydrate antigens on alpha dystroglycan, a finding similar to muscles in some forms of congenital muscular dystrophy. Here we describe one DG(S654A) transgenic line where VIA4-1 antibody binding is absent in skeletal muscle. In theory, the absence of this carbohydrate antigen should inhibit later glycosylation events that would occur on the structure or structures this antibody binds to. One such modification is likely to be the CT carbohydrate antigen, which is present on alpha dystroglycan in muscles overexpressing the CT GalNAc transferase [Dev. Biol. 242 (2002) 58]. To test the relationship between the VIA4-1 and CT carbohydrate antigens, we made DG(S654A)/CT GalNAc transferase (DG(S654A)/CT) transgenic mice. Surprisingly, dystroglycan was cleaved, and alpha dystroglycan was glycosylated with the VIA4-1 antigen, in DG(S654A)/CT muscles. In addition, muscles in DG(S654A)/CT transgenic mice had little or no evidence of muscular dystrophy when compared to DG(S654A) littermates. These experiments demonstrate that the CT GalNAc transferase can affect the post-translational processing of dystroglycan and the extent of muscular dystrophy even in muscles where the VIA4-1 antigen is not present.     

Guiding the folding of G-quadruplexes through loop residue interactions

A G-rich sequence was designed to allow folding into either a stable parallel or hybrid-type topology. With the parent sequence featuring coexisting species, various related sequences with single and double mutations and with a shortened central propeller loop affected the topological equilibrium. Two simple modifications, likewise introduced separately to all sequences, were employed to lock folds into one of the topologies without noticeable structural alterations. The unique combination of sequence mutations, high-resolution NMR structural information, and the thermodynamic stability for both topological competitors identified critical loop residue interactions. In contrast to first loop residues, which are mostly disordered and exposed to solvent in both propeller and lateral loops bridging a narrow groove, the last loop residue in a lateral three-nucleotide loop is engaged in stabilizing stacking interactions. The propensity of single-nucleotide loops to favor all-parallel topologies by enforcing a propeller-like conformation of an additional longer loop is shown to result from their preference in linking two outer tetrads of the same tetrad polarity. Taken together, the present studies contribute to a better structural and thermodynamic understanding of delicate loop interactions in genomic and artificially designed quadruplexes, e.g. when employed as therapeutics or in other biotechnological applications.     

Identification of Scleractinian Coral Recruits Using Fluorescent Censusing and DNA Barcoding Techniques

The identification of coral recruits has been problematic due to a lack of definitive morphological characters being available for higher taxonomic resolution. In this study, we tested whether fluorescent detection of coral recruits used in combinations of different DNA-barcoding markers (cytochrome oxidase I gene [COI], open reading frame [ORF], and nuclear Pax-C intron [PaxC]) could be useful for increasing the resolution of coral spat identification in ecological studies. One hundred and fifty settlement plates were emplaced at nine sites on the fringing reefs of Kenting National Park in southern Taiwan between April 2011 and September 2012. A total of 248 living coral spats and juveniles (with basal areas ranging from 0.21 to 134.57 mm²) were detected on the plates with the aid of fluorescent light and collected for molecular analyses. Using the COI DNA barcoding technique, 90.3% (224/248) of coral spats were successfully identified into six genera, including Acropora, Isopora, Montipora, Pocillopora, Porites, and Pavona. PaxC further separated I. cuneata and I. palifera of Isopora from Acropora, and ORF successfully identified the species of Pocillopora (except P. meandrina and P. eydouxi). Moreover, other cnidarian species such as actinarians, zoanthids, and Millepora species were visually found using fluorescence and identified by COI DNA barcoding. This combination of existing approaches greatly improved the taxonomic resolution of early coral life stages, which to date has been mainly limited to the family level based on skeletal identification. Overall, this study suggests important improvements for the identification of coral recruits in ecological studies.     

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation

Percutaneous electrical nerve stimulation is a non-invasive method commonly used to evaluate neuromuscular function from brain to muscle (supra-spinal, spinal and peripheral levels). The present protocol describes how this method can be used to stimulate the posterior tibial nerve that activates plantar flexor muscles. Percutaneous electrical nerve stimulation consists of inducing an electrical stimulus to a motor nerve to evoke a muscular response. Direct (M-wave) and/or indirect (H-reflex) electrophysiological responses can be recorded at rest using surface electromyography. Mechanical (twitch torque) responses can be quantified with a force/torque ergometer. M-wave and twitch torque reflect neuromuscular transmission and excitation-contraction coupling, whereas H-reflex provides an index of spinal excitability. EMG activity and mechanical (superimposed twitch) responses can also be recorded during maximal voluntary contractions to evaluate voluntary activation level. Percutaneous nerve stimulation provides an assessment of neuromuscular function in humans, and is highly beneficial especially for studies evaluating neuromuscular plasticity following acute (fatigue) or chronic (training/detraining) exercise.     

Purification, characterization and subunits identification of the diol dehydratase of Lactobacillus collinoides.

The three genes pduCDE encoding the diol dehydratase of Lactobacillus collinoides, have been cloned for overexpression in the pQE30 vector. Although the three subunits of the protein were highly induced, no activity was detected in cell extracts. The enzyme was therefore purified to near homogeneity by ammonium sulfate precipitation and gel filtration chromatography. In fractions showing diol dehydratase activity, three main bands were present after SDS/PAGE with molecular masses of 63, 28 and 22 kDa, respectively. They were identified by mass spectrometry to correspond to the large, medium and small subunits of the dehydratase encoded by the pduC, pduD and pduE genes, respectively. The molecular mass of the native complex was estimated to 207 kDa in accordance with the calculated molecular masses deduced from the pduC, D, E genes (61, 24.7 and 19,1 kDa, respectively) and a alpha2beta2gamma2 composition. The Km for the three main substrates were 1.6 mm for 1,2-propanediol, 5.5 mm for 1,2-ethanediol and 8.3 mm for glycerol. The enzyme required the adenosylcobalamin coenzyme for catalytic activity and the Km for the cofactor was 8 micro m. Inactivation of the enzyme was observed by both glycerol and cyanocobalamin. The optimal reaction conditions of the enzyme were pH 8.75 and 37 degrees C. Activity was inhibited by sodium and calcium ions and to a lesser extent by magnesium. A fourth band at 59 kDa copurified with the diol dehydratase and was identified as the propionaldehyde dehydrogenase enzyme, another protein involved in the 1,2-propanediol metabolism pathway.     

Mcl-1 and YY1 inhibition and induction of DR5 by the BH3-mimetic Obatoclax (GX15-070) contribute in the sensitization of B-NHL cells to TRAIL apoptosis

The pan Bcl-2 family antagonist Obatoclax (GX15-070), currently in clinical trials, was shown to sensitize TRAIL-resistant tumors to TRAIL-mediated apoptosis via the release of Bak and Bim from Mcl-1 or Bcl-2/Bcl-X_L complexes or by the activation of Bax, though other mechanisms were not examined. Herein, we hypothesize that Obatoclax-mediated sensitization to TRAIL apoptosis may also result from alterations of the apoptotic pathways. The TRAIL-resistant B-cell line Ramos was used as a model for investigation. Treatment of Ramos cells with obatoclax significantly inhibited the expression of several members of the Bcl-2 family, dissociated Bak from Mcl-1 and inhibited the NFκB activity. Cells treated with Mcl-1 siRNA were sensitized to TRAIL apoptosis. We examined whether the sensitization of Ramos to TRAIL by Obatoclax resulted from signaling of the DR4 and/or DR5. Transfection with DR5 siRNA, but not with DR4 siRNA, sensitized the cells to apoptosis following treatment with Obatoclax and TRAIL. The signaling via DR5 correlated with Obatoclax-induced inhibition of the DR5 repressor Yin Yang 1 (YY1). Transfection with YY1 siRNA sensitized the cells to TRAIL apoptosis following treatment with Obatoclax and TRAIL. Overall, the present findings reveal a new mechanism of Obatoclax-induced sensitization to TRAIL apoptosis and the involvement of the inhibition of NFκB activity and downstream Mcl-1 and YY1 expressions and activities.Key words: Obatoclax, TRAIL, YY1, DR5, lymphoma, immunosensitization     

CRTAM: A molecule involved in epithelial cell adhesion

Class I‐restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin‐like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell–cell contacts and cell–substrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell–cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti‐CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co‐cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans‐interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion. J. Cell. Biochem. 111: 111–122, 2010. © 2010 Wiley‐Liss, Inc.     

Humoral Immunity Links Candida albicans Infection and Celiac Disease

Objective

The protein Hwp1, expressed on the pathogenic phase of Candida albicans, presents sequence analogy with the gluten protein gliadin and is also a substrate for transglutaminase. This had led to the suggestion that C. albicans infection (CI) may be a triggering factor for Celiac disease (CeD) onset. We investigated cross-immune reactivity between CeD and CI.

Methods

Serum IgG levels against recombinant Hwp1 and serological markers of CeD were measured in 87 CeD patients, 41 CI patients, and 98 healthy controls (HC). IgA and IgG were also measured in 20 individuals from each of these groups using microchips sensitized with 38 peptides designed from the N-terminal of Hwp1.

Results

CI and CeD patients had higher levels of anti-Hwp1 (p=0.0005 and p=0.004) and anti-gliadin (p=0.002 and p=0.0009) antibodies than HC but there was no significant difference between CeD and CI patients. CeD and CI patients had higher levels of anti-transglutaminase IgA than HC (p=0.0001 and p=0.0039). During CI, the increase in anti-Hwp1 paralleled the increase in anti-gliadin antibodies. Microchip analysis showed that CeD patients were more reactive against some Hwp1 peptides than CI patients, and that some deamidated peptides were more reactive than their native analogs. Binding of IgG from CeD patients to Hwp1 peptides was inhibited by γIII gliadin peptides.

Conclusions

Humoral cross-reactivity between Hwp1 and gliadin was observed during CeD and CI. Increased reactivity to Hwp1 deamidated peptide suggests that transglutaminase is involved in this interplay. These results support the hypothesis that CI may trigger CeD onset in genetically-susceptible individuals.     

Lymphocytic Proliferative Response to Outer-Membrane Proteins Isolated from Salmonella

Porins isolated from Salmonella typhi have been demonstrated to protect against the challenge with this bacteria in mice. The mechanism has not been clarified, but could be associated with activation of both humoral and cellular immunity. In order to evaluate the induction of specific T cell responses, the lymphocytic proliferation to porins isolated from Salmonella typhimurium, Salmonella typhi and Escherichia coli was examined by ³H-thymidine incorporation assay in mice immunized with three different antigens: acetone-killed S. typhimurium, its porins, or outer-membrane proteins (OMPs) isolated from S. typhi. Higher proliferative responses were observed in mice immunized with porins and OMPs compared with those which received the acetone-killed bacteria. Although cross-reactivity was observed between porins, they were not mitogenic. Moreover, porins were able to activate T lymphocytes isolated from mice immunized with S. typhi OMPs. These results suggest that T cell activation, through the release of lymphokines, may play a role in the induction of protective immunity with porins.