Rapid biodiversity assessment and monitoring method for highly diverse benthic communities: a case study of mediterranean coralligenous outcrops

Increasing anthropogenic pressures urge enhanced knowledge and understanding of the current state of marine biodiversity. This baseline information is pivotal to explore present trends, detect future modifications and propose adequate management actions for marine ecosystems. Coralligenous outcrops are a highly diverse and structurally complex deep-water habitat faced with major threats in the Mediterranean Sea. Despite its ecological, aesthetic and economic value, coralligenous biodiversity patterns are still poorly understood. There is currently no single sampling method that has been demonstrated to be sufficiently representative to ensure adequate community assessment and monitoring in this habitat. Therefore, we propose a rapid non-destructive protocol for biodiversity assessment and monitoring of coralligenous outcrops providing good estimates of its structure and species composition, based on photographic sampling and the determination of presence/absence of macrobenthic species. We used an extensive photographic survey, covering several spatial scales (100s of m to 100s of km) within the NW Mediterranean and including 2 different coralligenous assemblages: Paramuricea clavata (PCA) and Corallium rubrum assemblage (CRA). This approach allowed us to determine the minimal sampling area for each assemblage (5000 cm(2) for PCA and 2500 cm(2) for CRA). In addition, we conclude that 3 replicates provide an optimal sampling effort in order to maximize the species number and to assess the main biodiversity patterns of studied assemblages in variability studies requiring replicates. We contend that the proposed sampling approach provides a valuable tool for management and conservation planning, monitoring and research programs focused on coralligenous outcrops, potentially also applicable in other benthic ecosystems.     

RhoE deficiency produces postnatal lethality, profound motor deficits and neurodevelopmental delay in mice

Rnd proteins are a subfamily of Rho GTPases involved in the control of actin cytoskeleton dynamics and other cell functions such as motility, proliferation and survival. Unlike other members of the Rho family, Rnd proteins lack GTPase activity and therefore remain constitutively active. We have recently described that RhoE/Rnd3 is expressed in the Central Nervous System and that it has a role in promoting neurite formation. Despite their possible relevance during development, the role of Rnd proteins in vivo is not known. To get insight into the in vivo function of RhoE we have generated mice lacking RhoE expression by an exon trapping cassette. RhoE null mice (RhoE gt/gt) are smaller at birth, display growth retardation and early postnatal death since only half of RhoE gt/gt mice survive beyond postnatal day (PD) 15 and 100% are dead by PD 29. RhoE gt/gt mice show an abnormal body position with profound motor impairment and impaired performance in most neurobehavioral tests. Null mutant mice are hypoactive, show an immature locomotor pattern and display a significant delay in the appearance of the hindlimb mature responses. Moreover, they perform worse than the control littermates in the wire suspension, vertical climbing and clinging, righting reflex and negative geotaxis tests. Also, RhoE ablation results in a delay of neuromuscular maturation and in a reduction in the number of spinal motor neurons. Finally, RhoE gt/gt mice lack the common peroneal nerve and, consequently, show a complete atrophy of the target muscles. This is the first model to study the in vivo functions of a member of the Rnd subfamily of proteins, revealing the important role of Rnd3/RhoE in the normal development and suggesting the possible involvement of this protein in neurological disorders.     

Mechanisms Governing the Endosomal Membrane Recruitment of the Core Retromer in Arabidopsis

The retromer complex localizes to endosomal membranes and is involved in protein trafficking. In mammals, it is composed of a dimer of sorting nexins and of the core retromer consisting of vacuolar protein sorting (VPS)26, VPS29, and VPS35. Although homologs of these proteins have been identified in plants, how the plant retromer functions remains elusive. To better understand the role of VPS components in the assembly and function of the core retromer, we characterize here Arabidopsis vps26-null mutants. We show that impaired VPS26 function has a dramatic effect on VPS35 levels and causes severe phenotypic defects similar to those observed in vps29-null mutants. This implies that functions of plant VPS26, VPS29, and VPS35 are tightly linked. Then, by combining live-cell imaging with immunochemical and genetic approaches, we report that VPS35 alone is able to bind to endosomal membranes and plays an essential role in VPS26 and VPS29 membrane recruitment. We also show that the Arabidopsis Rab7 homolog RABG3f participates in the recruitment of the core retromer to the endosomal membrane by interacting with VPS35. Altogether our data provide original information on the molecular interactions that mediate assembly of the core retromer in plants.     

An integrative systematic approach to species diversity and distribution in the genus Mesophyllum (Corallinales,Rhodophyta) in Atlantic and Mediterranean Europe

For the first time, a comprehensive assessment of Mesophyllum species diversity and their distribution in Atlantic Europe and the Mediterranean Sea is presented based on molecular (COI-5P, psbA) and morphological data. The distribution ranges were redefined for the four species collected in this study: M. alternans, M. expansum, M. macroblastum and M. sphaericum. Mesophyllum sphaericum, which was previously known only from a single maerl bed in Galicia (NW Spain), is reported from the Mediterranean Sea. The known range of M. expansum (Mediterranean and Macaronesia) was extended to the Atlantic Iberian Peninsula. The occurrence of M. alternans was confirmed along the Atlantic French coast south to Algarve (southern Portugal). Mesophyllum lichenoides was only recorded from the Atlantic, whereas M. macroblastum appears to be restricted to the Mediterranean Sea. A positive correlation was observed between maximum Sea Surface Temperature (SSTmax) and the depth at which M. expansum was collected, suggesting that this species may compensate for higher SST by growing in deeper habitats where the temperature is lower. The latter indicates that geographic shifts in the distribution of coastal species as a result of global warming can possibly be mitigated by changes in the depth profile at which these species occur. Mesophyllum expansum, an important builder of Mediterranean coralligenous habitats, may be a good target species to assess its response to climate change.     

A2A adenosine receptor ligand binding and signalling is allosterically modulated by adenosine deaminase

A2ARs (adenosine A2A receptors) are highly enriched in the striatum, which is the main motor control CNS (central nervous system) area. BRET (bioluminescence resonance energy transfer) assays showed that A2AR homomers may act as cell-surface ADA (adenosine deaminase; EC 3.5.4.4)-binding proteins. ADA binding affected the quaternary structure of A2ARs present on the cell surface. ADA binding to adenosine A2ARs increased both agonist and antagonist affinity on ligand binding to striatal membranes where these proteins are co-expressed. ADA also increased receptor-mediated ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation. Collectively, the results of the present study show that ADA, apart from regulating the concentration of extracellular adenosine, may behave as an allosteric modulator that markedly enhances ligand affinity and receptor function. This powerful regulation may have implications for the physiology and pharmacology of neuronal A2ARs.     

Effect of dietary selenite on development and intestinal absorption in offspring rats

AimThe present study aims to compare selenium (Se) status in offspring rats born to selenium-deficient and selenium supplemented dams and to analyse Se's influence on intestinal parameters and the intestinal absorption of selenomethionine (Se-Met).Main methodsMale and female Wistar rats (150–200 g) were randomised in: control (C) (0.1 ppm Se), Se-deficient (SD) (0.01 ppm Se) and Se-supplemented (SS) (0.5 ppm Se) groups; and were mated to obtain their offspring. Se levels in serum, urine and faeces in offspring and in mothers' milk were measured by graphite-furnace atomic absorption spectrometry. Duodenal transport studies in offspring were performed using an in vivo perfusion of different Se-Met concentrations (2, 5, 10, 25, 75 and 150 μM).Key findingA Se-deficient diet provoked a decrease in the offspring's body weight and intestinal parameters, while the supplemented diet increased these values. Serum Se levels were similar between Se-deficient and control offspring because the urinary excretion of Se was smaller to compensate for Se homeostasis. Intestinal Se-Met absorption obeys the Michaellis–Menten equation with lower apparent constant (K_m) and maximal velocity (V_max) in the SD group. However, the C and SS groups presented similar K_m and different V_max. The V_max showed greater values in the following order of rank: SS > C > SD groups.SignificanceSelenium intake deficiencies in offspring lead to the development of compensatory mechanisms in order to normalise serum selenium levels. These mechanisms, however, do not permit normal body development; nor do they regulate intestinal parameters and Se-Met transport.     

Signalling through kinase-defective domains: the prevalence of atypical receptor-like kinases in plants

The structure of plant receptor-like kinases (RLKs) is similar to that of animal receptor tyrosine kinases (RTKs), and consists of an extracellular domain, a transmembrane span, and a cytoplasmic domain containing the conserved kinase domain. The mechanism by which animal RTKs, and probably plant RLKs, signal includes the dimerization of the receptor, their intermolecular phosphorylation, and the phosphorylation of downstream signalling proteins. However, atypical RTKs with a kinase-dead domain that signal through phosphorylation-independent mechanisms have also been described in animals. In the last few years, some atypical RLKs have also been reported in plants. Here these examples and their possible signalling mechanisms are reviewed. Plant genomes contain a much larger number of genes coding for receptor kinases than other organisms. The prevalence of atypical RLKs in plants is analysed here. A sequence analysis of the Arabidopsis kinome revealed that 13% of the kinase genes do not retain some of the residues that are considered as invariant within kinase catalytic domains, and are thus putatively kinase-defective. This percentage rises to close to 20% when analysing RLKs, suggesting that phosphorylation-independent mechanisms mediated by atypical RLKs are particularly important for signal transduction in plants.     

Simvastatin and atorvastatin enhance gene expression of collagen type 1 and osteocalcin in primary human osteoblasts and MG-63 cultures

To clarify the mechanism of the stimulatory effect of statins on bone formation, we have assessed the effect of simvastatin and atorvastatin on osteoblast activity by analysing cell proliferation, as well as collagen, osteocalcin, and bone morphogenetic protein-2 (BMP2) gene expression in primary human osteoblast (hOB) and MG-63 cell line cultures. Explants of bone from patients without any metabolic disease under orthopedic hip procedures were used to obtain hOB. Cell cultures were established, synchronized, and different concentrations of simvastatin or atorvastatin were added (10(-9) M, 10(-8) M, 10(-7) M, 10(-6) M) during the experiment. Cell proliferation was analyzed after 24 h. Collagen polypeptide alpha1 type 1 (COL1A1) gene expression, osteocalcin, and BMP2 expression levels were quantified by real-time PCR after 24 h incubation with statins. There was a statistically significant decrease in cell proliferation related to simvastatin or atorvastatin addition at all concentrations in primary hOB compared with those not treated. A significant increase in COL1A1, osteocalcin, and BMP2 gene expression was detected when hOB cultures were treated with simvastatin or atorvastatin at different concentrations. Similar but less significant effects were found on MG-63 cells. After statin treatment we observed both an arrest of proliferation in hOB cells and an increase in collagen, osteocalcin, and BMP2 gene expression, consistent with a stimulatory effect towards mature osteoblast differentiation. These findings support the bone-forming effect of statins, probably through the BMP2 pathway.     

Catheter ablation of atrial incisional tachycardia mistaken for atrial flutter

Incisional sustained tachycardias are frequent in patients who have undergone a surgical repair of interatrial defect. A 43-year-old woman with drug refractory, highly symptomatic, persistent atrial tachycardia in the last year, was referred to our unit for catheter ablation. The patient had undergone a cardiac operation for repairing interatrial secundum ostium type defect with a patch five years before. A previous radiofrequency ablation procedure had been performed for common atrial flutter. We describe a case of incisional atrial tachycardia ablation guided by the new EnSite NavX system equipped with a new electroanatomic mapping system.