Amphidoma languida (Amphidomatacea,Dinophyceae) with a novel azaspiracid toxin profile identified as the cause of molluscan contamination at the Atlantic coast of southern Spain

Azaspiracids (AZA) are a group of food poisoning phycotoxins that are known to accumulate in shellfish. They are produced by some species of the planktonic dinophycean taxon Amphidomataceae. Azaspiracids have been first discovered in Ireland but are now reported in shellfish from numerous global sites thus showing a wide distribution. In shellfish samples collected in 2009 near Huelva (Spain), AZA was also found along the Andalusian Atlantic coast for the first time. Analysis using LC–MS/MS revealed the presence of two different AZA analogues in different bivalve shellfish species (Chamelea gallina, Cerastoderma edule, Donax trunculus, and Solen vagina). In a number of samples, AZA levels exceeded the EU regulatory level of 160 μg AZA-1 eq. kg⁻¹ (reaching maximum levels of >500 μg AZA-1 eq. kg⁻¹ in Chamelea gallina and >250 μg AZA-1 eq. kg⁻¹ in Donax trunculus) causing closures of some local shellfish production areas. One dinophyte strain established from the local plankton during the AZA contamination period and determined as Amphidoma languida was in fact toxigenic, and its AZA profile disclosed it as the causative species: it contained AZA-2 as the main compound and the new compound AZA-43 initially detected in the shellfish. AZA-43 had the same mass as AZA-3, but produced different collision induced dissociation (CID) spectra. High resolution mass spectrometric measurements indicated that there is an unsaturation in the H, I ring system of AZA-43 distinguishing it from the classical AZA such as AZA-1, -2, and -3. Furthermore, the Spanish strain was different from the previously reported AZA profile of the species that consist of AZA-38 and AZ-39. In molecular phylogenetics, the Andalusian strain formed a monophyletic group together with other strains of Am. languida, but ITS sequences data revealed surprisingly high intragenomic variability. The first Andalusian case of AZA contamination of shellfish above the EU regulatory limit reported here clearly revealed the risk of azaspiracid poisoning (AZP) for this area and also for the Atlantic coast of Iberia and North Africa. The present study underlines the need for continuous monitoring of AZA and the organisms producing such toxins.     

Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

Intrinsic processes are assumed to underlie life history expression and trade‐offs, but extrinsic inputs are theorised to shift trait expression and mask trade‐offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass‐specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade‐off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade‐offs across species.     

Lysine Succinylation of VBS Contributes to Sclerotia Development and Aflatoxin Biosynthesis in Aspergillus flavus

Aspergillus flavus is a common saprophytic and pathogenic fungus, and its secondary metabolic pathways are one of the most highly characterized owing to its aflatoxin (AF) metabolite affecting global economic crops and human health. Different natural environments can cause significant variations in AF synthesis. Succinylation was recently identified as one of the most critical regulatory post-translational modifications affecting metabolic pathways. It is primarily reported in human cells and bacteria with few studies on fungi. Proteomic quantification of lysine succinylation (Ksuc) exploring its potential involvement in secondary metabolism regulation (including AF production) has not been performed under natural conditions in A. flavus. In this study, a quantification method was performed based on tandem mass tag labeling and antibody-based affinity enrichment of succinylated peptides via high accuracy nano-liquid chromatography with tandem mass spectrometry to explore the succinylation mechanism affecting the pathogenicity of naturally isolated A. flavus strains with varying toxin production. Altogether, 1240 Ksuc sites in 768 proteins were identified with 1103 sites in 685 proteins quantified. Comparing succinylated protein levels between high and low AF-producing A. flavus strains, bioinformatics analysis indicated that most succinylated proteins located in the AF biosynthetic pathway were downregulated, which directly affected AF synthesis. Versicolorin B synthase is a key catalytic enzyme for heterochrome B synthesis during AF synthesis. Site-directed mutagenesis and biochemical studies revealed that versicolorin B synthase succinylation is an important regulatory mechanism affecting sclerotia development and AF biosynthesis in A. flavus. In summary, our quantitative study of the lysine succinylome in high/low AF-producing strains revealed the role of Ksuc in regulating AF biosynthesis. We revealed novel insights into the metabolism of AF biosynthesis using naturally isolated A. flavus strains and identified a rich source of metabolism-related enzymes regulated by succinylation.     

A neutron activation technique for manganese measurements in humans

Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Studies show that Mn metabolism is similar to that of iron, therefore, increased Mn levels in humans could interfere with the absorption of dietary iron leading to anemia. Also, excess exposure to Mn dust, leads to nervous system disorders similar to Parkinson's disease. Higher exposure to Mn is essentially related to industrial pollution. Thus, there is a benefit in developing a clean non-invasive technique for monitoring such increased levels of Mn in order to understand the risk of disease and development of appropriate treatments.To this end, the feasibility of Mn measurements with their minimum detection limits (MDL) has been reported earlier from the McMaster group. This work presents improvement to Mn assessment using an upgraded system and optimized times of irradiation and counting for induced gamma activity of Mn. The technique utilizes the high proton current Tandetron accelerator producing neutrons via the ⁷Li(p,n)⁷Be reaction at McMaster University and an array of nine NaI (Tl) detectors in a 4π geometry for delayed counting of gamma rays. The neutron irradiation of a set of phantoms was performed with protocols having different proton energy, current and time of irradiation. The improved MDLs estimated using the upgraded set up and constrained timings are reported as 0.67 μgMn/gCa for 2.3 MeV protons and 0.71 μgMn/gCa for 2.0 MeV protons. These are a factor of about 2.3 times better than previous measurements done at McMaster University using the in vivo set-up. Also, because of lower dose-equivalent and a relatively close MDL, the combination of: 2.0 MeV; 300 μA; 3 min protocol is recommended as compared to 2.3 MeV; 400 μA; 45 s protocol for further measurements of Mn in vivo.     

Ensembles of endothelial and mural cells promote angiogenesis in prenatal human brain

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Angiotensin converting enzyme gene polymorphism studies: A case-control study

Mild gestational hyperglycemia (MGH) is a very common complication of pregnancy that is characterized by intolerance to glucose. The association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism to MGH has been previously reported. In this study, we evaluated the association between ACE polymorphism and the risk of MGH in a Saudi population. We conducted a case-control study in a population of 100 MGH patients and 100 control subjects. ACE gene polymorphism was analyzed by the novel approach of tetraprimer amplification refractory mutation system (ARMS)-polymerase chain reaction (PCR). The frequency of ACE polymorphism was not associated with either alleles or genotypes in MGH patients. Glucose concentration was found to be significantly associated with the MGH group. Our study suggests that ACE genotypes were not associated with ACE polymorphism in a Saudi population.     

New triterpene saponins from the seed cake of Camellia Oleifera and their cytotoxic activity

Two new oleanane-type triterpene saponins, identified as 16α-hydroxy-22-O-angeloyl-23-formyl-28,31-dihydroxymethylene-olean-12-ene-3β-O-{β-d-galactopyranosyl-(1 → 2)[β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl(1 → 3)]-β-d-glucopyranosiduronic acid} (oleiferasaponin B₁, 1) and 22-O-hydrocinnamoyl-23-formyl-28-dihydroxymethylene-olean-12-ene-3β-O-{β-d-glucopyranosyl-(1 → 2)[β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl(1 → 3)]-β-d-glucopyranosiduronic acid} (oleiferasaponin B₂, 2), were isolated from the seed cake of Camellia oleifera Abel. Their structures were established by extensive 1D- and 2D-NMR experiments along with TOF-MS analysis and acid hydrolysis. The cytotoxicity of the isolated compounds was evaluated in four human carcinoma cell lines: A 549, SK-OV-3, SK-MEL-2 and HCT15. Both compounds 1 and 2 exhibited significantly cytotoxic activity with IC₅₀ values of 18.5 μM (A549), 11.3 μM (SK-OV-3), 13.9 μM (SK-MEL-2) and 1.6 μM (HCT15) for 1 and IC₅₀ values of 8.4 μM (A549), 6.3 μM (SK-OV-3), 9.2 μM (SK-MEL-2) and 0.8 μM (HCT15) for 2. In addition, compound 2 showed more effective cytotoxic activity than compound 1.     

Pay attention to membrane tension: Mechanobiology of the cell surface

The cell surface is a mechanobiological unit that encompasses the plasma membrane, its interacting proteins, and the complex underlying cytoskeleton. Recently, attention has been directed to the mechanics of the plasma membrane, and in particular membrane tension, which has been linked to diverse cellular processes such as cell migration and membrane trafficking. However, how tension across the plasma membrane is regulated and propagated is still not completely understood. Here, we review recent efforts to study the interplay between membrane tension and the cytoskeletal machinery and how they control cell form and function. We focus on factors that have been proposed to affect the propagation of membrane tension and as such could determine whether it can act as a global or local regulator of cell behavior. Finally, we discuss the limitations of the available tool kit as new approaches that reveal its dynamics in cells are needed to decipher how membrane tension regulates diverse cellular processes.