QUANTITATIVE REAL‐TIME POLYMERASE CHAIN REACTION FOR COCHLODINIUM FULVESCENS (DINOPHYCEAE), A HARMFUL DINOFLAGELLATE FROM CALIFORNIA COASTAL WATERS1

Harmful blooms formed by species of the dinoflagellate Cochlodinium have caused massive fish kills and substantial economic losses in the Pacific Ocean. Recently, prominent blooms of Cochlodinium have occurred in central and southern California (2004–2008), and Cochlodinium cells are now routinely observed in microscopical analysis of algal assemblages from Californian coastal waters. The first documented economic loss due to a Cochlodinium bloom in California occurred in Monterey Bay and resulted in the mortality of commercially farmed abalone. Increasing occurrences of Cochlodinium blooms, the fact that these cells preserve poorly using standard techniques, and the difficulty of identifying preserved specimens using morphological criteria make Cochlodinium species prime candidates for the development of a quantitative real‐time polymerase chain reaction (qPCR) approach. The 18S rDNA gene sequenced from Cochlodinium cells obtained from California coastal waters, as well as GenBank sequences of Cochlodinium, were used to design and test a Molecular Beacon^® approach. The qPCR method developed in this study is species specific, sensitive for the detection of C. fulvescens that has given rise to the recent blooms in the eastern Pacific Ocean, and spans a dynamic abundance range of seven orders of magnitude. Initial application of the method to archived field samples collected during blooms in Monterey Bay revealed no statistically significant correlations between gene copy number and environmental parameters. However, the onset of Cochlodinium blooms in central California was consistent with previously reported findings of correlations to decreased surface temperature and increased inputs of nitrogenous nutrients.     

Homo- and heterodimeric Smac mimetics/IAP inhibitors as in vivo-active pro-apoptotic agents. Part I: Synthesis

Novel pro-apoptotic, homo- and heterodimeric Smac mimetics/IAPs inhibitors based on the N-AVPI-like 4-substituted 1-aza-2-oxobicyclo[5.3.0]decane scaffold were prepared from monomeric structures connected through a head–head (8), tail–tail (9) or head–tail (10) linker. The selection of appropriate decorating functions for the scaffolds, and of rigid and flexible linkers connecting them, is described. The synthesis, purification and analytical characterization of each prepared dimer 8–10 is thoroughly described.     

Gastric cancer prevention targeted on risk assessment: Gastritis OLGA staging

Gastric cancer (GC) ranks among the most lethal epithelial malignancies, and its striking mortality rate prompts a global prevention strategy. Helicobacter pylori (H. pylori) gastritis is the main GC promoter, and the 2014 Global Kyoto conference recognized H. pylori gastritis as a (treatable) infectious disease. It is therefore plausible that any large‐scale intervention for H. pylori eradication would result in cleansing the world of the fifth cause of cancer‐related death. Atrophic gastritis is the cancerization field in which GCs (both intestinal and diffuse histotypes) mainly develop. Discontinuing the inflammatory cascade triggered by H. pylori is tantamount to preventing GC. For patients (still infected or eradicated) who have already developed gastric atrophy, the severity/topography of the atrophic changes correlates with their cancer risk. Gastritis OLGA (Operative Link for Gastritis Assessment) staging consistently ranks the atrophy‐associated cancer risk, providing a solid clinical/biological rationale for establishing patient‐specific surveillance programs. By combining primary and secondary prevention strategies, gastric cancer is a preventable disease.     

Novel biochemical pathways of endoglin in vascular cell physiology

The broad role of the transforming growth factor beta (TGFbeta) signaling pathway in vascular development, homeostasis, and repair is well appreciated. Endoglin is emerging as a novel, complex, and poorly understood regulatory component of the TGFbeta receptor complex, whose importance is underscored by its recognition as the site of mutations causing hereditary hemorrhagic telangiectasia (HHT) [McAllister et al., 1994]. Extensive analyses of endoglin function in normal developmental mouse models [Bourdeau et al., 1999; Li et al., 1999; Arthur et al., 2000] and in HHT animal models [Bourdeau et al., 2000; Torsney et al., 2003] exemplify the importance of understanding endoglin's biochemical functions. However, novel mechanisms underlying the regulation of these pathways continue to emerge. These mechanisms include modification of TGFbeta receptor signaling at the ligand and receptor activation level, direct effects of endoglin on cell adhesion and migration, and emerging roles for endoglin in the determination of stem cell fate and tissue patterning. The purpose of this review is to highlight the cellular and molecular studies that underscore the central role of endoglin in vascular development and disease.     

The limited spatial scale of dispersal in soil arthropods revealed with whole‐community haplotype‐level metabarcoding

Soil arthropod communities are highly diverse and critical for ecosystem functioning. However, our knowledge of spatial structure and the underlying processes of community assembly are scarce, hampered by limited empirical data on species diversity and turnover. We implement a high‐throughput sequencing approach to generate comparative data for thousands of arthropods at three hierarchical levels: genetic, species and supra‐specific lineages. A joint analysis of the spatial arrangement across these levels can reveal the predominant processes driving the variation in biological assemblages at the local scale. This multihierarchical approach was performed using haplotype‐level COI metabarcoding of entire communities of mites, springtails and beetles from three Iberian mountain regions. Tens of thousands of specimens were extracted from deep and superficial soil layers and produced comparative phylogeographic data for >1,000 codistributed species and nearly 3,000 haplotypes. Local assemblage composition differed greatly between grasslands and forests and, within each habitat, showed strong spatial structure and high endemicity. Distance decay was high at all levels, even at the scale of a few kilometres or less. The local distance decay patterns were self‐similar for the haplotypes and higher hierarchical entities, and this fractal structure was similar in all regions, suggesting that uniform processes of limited dispersal determine local‐scale community assembly. Our results from whole‐community metabarcoding provide insight into how dispersal limitations constrain mesofauna community structure within local spatial settings over evolutionary timescales. If generalized across wider areas, the high turnover and endemicity in the soil locally may indicate extremely high richness globally, challenging our current estimations of total arthropod diversity on Earth.     

The role of heterogenous environmental conditions in shaping the spatiotemporal distribution of competing Aedes mosquitoes in Panama: implications for the landscape of arboviral disease transmission

Monitoring the invasion process of the Asian tiger mosquito Aedes albopictus and its interaction with the contender Aedes aegypti, is critical to prevent and control the arthropod-borne viruses (i.e., Arboviruses) they transmit to humans. Generally, the superior ecological competitor Ae. albopictus displaces Ae. aegypti from most geographic areas, with the combining factors of biology and environment influencing the competitive outcome. Nonetheless, detailed studies asserting displacement come largely from sub-tropical areas, with relatively less effort being made in tropical environments, including no comprehensive research about Aedes biological interactions in Mesoamerica. Here, we examine contemporary and historical mosquito surveillance data to assess the role of shifting abiotic conditions in shaping the spatiotemporal distribution of competing Aedes species in the Republic of Panama. In accordance with prior studies, we show that Ae. albopictus has displaced Ae. aegypti under suboptimal wet tropical climate conditions and more vegetated environments within the southwestern Azuero Peninsula. Conversely, in the eastern Azuero Peninsula, Ae. aegypti persists with Ae. albopictus under optimal niche conditions in a dry and more seasonal tropical climate. While species displacement was stable over the course of two years, the presence of both species generally appears to fluctuate in tandem in areas of coexistence. Aedes albopictus was always more frequently found and abundant regardless of location and climatic season. The heterogenous environmental conditions of Panama shape the competitive outcome and micro-geographic distribution of Aedes mosquitoes, with potential consequences for the transmission dynamics of urban and sylvatic zoonotic diseases.

     

Phylogenetic relationships,morphological variation,and toxin patterns in the Alexandrium ostenfeldii (Dinophyceae) complex: implications for species boundaries and identities

Alexandrium ostenfeldii (Paulsen) Balech and Tangen and A. peruvianum (Balech and B.R. Mendiola) Balech and Tangen are morphologically closely related dinoflagellates known to produce potent neurotoxins. Together with Gonyaulax dimorpha Biecheler, they constitute the A. ostenfeldii species complex. Due to the subtle differences in the morphological characters used to differentiate these species, unambiguous species identification has proven problematic. To better understand the species boundaries within the A. ostenfeldii complex we compared rDNA data, morphometric characters and toxin profiles of multiple cultured isolates from different geographic regions. Phylogenetic analysis of rDNA sequences from cultures characterized as A. ostenfeldii or A. peruvianum formed a monophyletic clade consisting of six distinct groups. Each group examined contained strains morphologically identified as either A. ostenfeldii or A. peruvianum. Though key morphological characters were generally found to be highly variable and not consistently distributed, selected plate features and toxin profiles differed significantly among phylogenetic clusters. Additional sequence analyses revealed a lack of compensatory base changes in ITS2 rRNA structure, low to intermediate ITS/5.8S uncorrected genetic distances, and evidence of reticulation. Together these data (criteria currently used for species delineation in dinoflagellates) imply that the A. ostenfeldii complex should be regarded a single genetically structured species until more material and alternative criteria for species delimitation are available. Consequently, we propose that A. peruvianum is a heterotypic synonym of A. ostenfeldii and this taxon name should be discontinued.     

Tempo and mode of the multiple origins of salinity tolerance in a water beetle lineage

Salinity is one of the most important drivers of the distribution, abundance and diversity of organisms. Previous studies on the evolution of saline tolerance have been mainly centred on marine and terrestrial organisms, while lineages inhabiting inland waters remain largely unexplored. This is despite the fact that these systems include a much broader range of salinities, going from freshwater to more than six times the salinity of the sea (i.e. >200 g/L). Here, we study the pattern and timing of the evolution of the tolerance to salinity in an inland aquatic lineage of water beetles (Enochrus species of the subgenus Lumetus, family Hydrophilidae), with the general aim of understanding the mechanisms by which it was achieved. Using a time‐calibrated phylogeny built from five mitochondrial and two nuclear genes and information about the salinity tolerance and geographical distribution of the species, we found that salinity tolerance appeared multiple times associated with periods of global aridification. We found evidence of some accelerated transitions from freshwater directly to high salinities, as reconstructed with extant lineages. This, together with the strong positive correlation found between salinity tolerance and aridity of the habitats in which species are found, suggests that tolerance to salinity may be based on a co‐opted mechanism developed originally for drought resistance.