Cyanobacterial dominance in Brazil: distribution and environmental preferences

Based on a literature survey, we evaluated the periods of cyanobacterial dominance in Brazil. We hypothesized that variability of environmental forces along the country will promote or facilitate temporal and spatial mosaic in cyanobacterial dominance. The most striking outcomes are related to the dominance of Cylindrospermopsis, Dolichospermum, and Microcystis. Although they share important adaptive strategies (e.g., aerotopes, large size and toxins production), our findings suggest that they have different environmental preferences. Dolichospermum and Microcystis dominated mainly in warm-rainy periods whereas Cylindrospermopsis was more common during dry periods and in mixed systems, or formed perennial dominance. Maximum phosphorus concentrations were observed in reservoirs dominated by Cylindrospermopsis. Although the main genera reached high biomass levels individually, different abilities to form dominance and co-dominance were observed. The number of co-dominance of Chroococales and Nostocales was almost the same as the individual occurrence of the main genera from these groups. This dataset reveals patterns of dominance of these cyanobacteria and also indicates that physiological features will cause differences in the mechanisms of interactions between species. The understanding of these processes and their relationship to environmental conditions will promote better understanding of cyanobacterial dominance and increase our ability to predict and manage these events.     

Impact of Obstructive Sleep Apnea on the Levels of Placental Growth Factor (PlGF) and Their Value for Predicting Short-Term Adverse Outcomes in Patients with Acute Coronary Syndrome

Background

Placental growth factor (PlGF) induces angiogenesis and promotes tissue repair, and plasma PlGF levels change markedly during acute myocardial infarction (AMI). Currently, the impact of obstructive sleep apnea (OSA) in patients with AMI is a subject of debate. Our objective was to evaluate the relationships between PlGF levels and both the severity of acute coronary syndrome (ACS) and short-term outcomes after ACS in patients with and without OSA.

Methods

A total of 538 consecutive patients (312 OSA patients and 226 controls) admitted for ACS were included in this study. All patients underwent polygraphy in the first 72 hours after hospital admission. The severity of disease and short-term prognoses were evaluated during the hospitalization period. Plasma PlGF levels were measured using an electrochemiluminescence immunoassay.

Results

Patients with OSA were significantly older and more frequently hypertensive and had higher BMIs than those without OSA. After adjusting for age, smoking status, BMI and hypertension, PlGF levels were significantly elevated in patients with OSA compared with patients without OSA (19.9 pg/mL, interquartile range: 16.6–24.5 pg/mL; 18.5 pg/mL, interquartile range: 14.7–22.7 pg/mL; p<0.001), and a higher apnea-hypopnea index (AHI) was associated with higher PlGF concentrations (p<0.003). Patients with higher levels of PlGF had also an increased odds ratio for the presence of 3 or more diseased vessels and for a Killip score>1, even after adjustment.

Conclusions

The results of this study show that in patients with ACS, elevated plasma levels of PlGF are associated with the presence of OSA and with adverse outcomes during short-term follow-up.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01335087","term_id":"NCT01335087"}}NCT01335087     

Inhibition of Phosphoinositide 3-Kinase p110delta Does Not Affect T Cell Driven Development of Type 1 Diabetes Despite Significant Effects on Cytokine Production

Type 1 diabetes is caused by the destruction of insulin producing beta cells by the immune system. The p110δ isoform of PI3K is expressed primarily in cells of haematopoietic origin and the catalytic activity of p110δ is important for the activation of these cells. Targeting of this pathway offers an opportunity to reduce immune cell activity without unwanted side effects. We have explored the effects of a specific p110δ isoform inhibitor, IC87114, on diabetogenic T cells both in vitro and in vivo, and find that although pharmacological inhibition of p110δ has a considerable impact on the production of pro-inflammatory cytokines, it does not delay the onset of diabetes after adoptive transfer of diabetogenic cells. Further, we demonstrate that combination treatment with CTLA4-Ig does not improve the efficacy of treatment, but instead attenuates the protective effects seen with CTLA4-Ig treatment alone. Our results suggest that decreased IL-10 production by Foxp3⁺ CD4⁺ T cells in the presence of IC87114 negates individual anti-inflammatory effects of IC8114 and CTLA4-Ig.     

Salinity tolerance is related to cyanide‐resistant alternative respiration in Medicago truncatula under sudden severe stress

Salt respiration is defined as the increase of respiration under early salt stress. However, the response of respiration varies depending on the degree of salt tolerance and salt stress. It has been hypothesized that the activity of the alternative pathway may increase preventing over‐reduction of the ubiquinone pool in response to salinity, which in turn can increase respiration. Three genotypes of Medicago truncatula are reputed as differently responsive to salinity: TN1.11, A17 and TN6.18. We used the oxygen‐isotope fractionation technique to study the in vivo respiratory activities of the cytochrome oxidase pathway (COP) and the alternative oxidase pathway (AOP) in leaves and roots of these genotypes treated with severe salt stress (300 mM) during 1 and 3 days. In parallel, AOX capacity, gas exchange measurements, relative water content and metabolomics were determined in control and treated plants. Our study shows for first time that salt respiration is induced by the triggered AOP in response to salinity. Moreover, this phenomenon coincides with increased levels of metabolites such as amino and organic acids, and is shown to be related with higher photosynthetic rate and water content in TN6.18.     

Regime shifts of Mediterranean forest carbon uptake and reduced resilience driven by multidecadal ocean surface temperatures

The mechanisms translating global circulation changes into rapid abrupt shifts in forest carbon capture in semi‐arid biomes remain poorly understood. Here, we report unprecedented multidecadal shifts in forest carbon uptake in semi‐arid Mediterranean pine forests in Spain over 1950–2012. The averaged carbon sink reduction varies between 31% and 37%, and reaches values in the range of 50% in the most affected forest stands. Regime shifts in forest carbon uptake are associated with climatic early warning signals, decreased forest regional synchrony and reduced long‐term carbon sink resilience. We identify the mechanisms linked to ocean multidecadal variability that shape regime shifts in carbon capture. First, we show that low‐frequency variations of the surface temperature of the Atlantic Ocean induce shifts in the non‐stationary effects of El Niño Southern Oscillation (ENSO) on regional forest carbon capture. Modelling evidence supports that the non‐stationary effects of ENSO can be propagated from tropical areas to semi‐arid Mediterranean biomes through atmospheric wave trains. Second, decadal changes in the Atlantic Multidecadal Oscillation (AMO) significantly alter sea–air heat exchanges, modifying in turn ocean vapour transport over land and land surface temperatures, and promoting sustained drought conditions in spring and summer that reduce forest carbon uptake. Third, we show that lagged effects of AMO on the winter North Atlantic Oscillation also contribute to the maintenance of long‐term droughts. Finally, we show that the reported strong, negative effects of ocean surface temperature (AMO) on forest carbon uptake in the last decades are unprecedented over the last 150 years. Our results provide new, unreported explanations for carbon uptake shifts in these drought‐prone forests and review the expected impacts of global warming on the profiled mechanisms.     

The chromosome-scale assembly of the Canary Islands endemic spider Dysdera silvatica (Arachnida,Araneae) sheds light on the origin and genome structure of chemoreceptor gene families in chelicerates

Here, we present the chromosome-level genome assembly of Dysdera silvatica Schmidt, 1981, a nocturnal ground-dwelling spider endemic from the Canary Islands. The genus Dysdera has undergone a remarkable diversification in this archipelago mostly associated with shifts in the level of trophic specialization, becoming an excellent model to study the genomic drivers of adaptive radiations. The new assembly (1.37 Gb; scaffold N50 of 174.2 Mb), was performed using the chromosome conformation capture scaffolding technique, represents a continuity improvement of more than 4500 times with respect to the previous version. The seven largest scaffolds or pseudochromosomes, which cover 87% of the total assembly size, probably correspond with the seven chromosomes of the karyotype of this species, including a characteristic large X chromosome. To illustrate the value of this new resource we performed a comprehensive analysis of the two major arthropod chemoreceptor gene families (i.e., gustatory and ionotropic receptors). We identified 545 chemoreceptor sequences distributed across all pseudochromosomes, with a notable underrepresentation in the X chromosome. At least 54% of them localize in 83 genomic clusters with a significantly lower evolutionary distances between them than the average of the family, suggesting a recent origin of many of them. This chromosome-level assembly is the first high-quality genome representative of the Synspermiata clade, and just the third among spiders, representing a new valuable resource to gain insights into the structure and organization of chelicerate genomes, including the role that structural variants, repetitive elements and large gene families played in the extraordinary biology of spiders.     

A field portable method for the semi‐quantitative estimation of dehydration tolerance of photosynthetic tissues across distantly related land plants

Desiccation tolerant (DT) plants withstand complete cellular dehydration, reaching relative water contents (RWC) below 30% in their photosynthetic tissues. Desiccation sensitive (DS) plants exhibit different degrees of dehydration tolerance (DHT), never surviving water loss >70%. To date, no procedure for the quantitative evaluation of DHT extent exists that is able to discriminate DS species with differing degrees of DHT from truly DT plants. We developed a simple, feasible and portable protocol to differentiate between DT and different degrees of DHT in the photosynthetic tissues of seed plants and between fast desiccation (< 24 h) tolerant (FDT) and sensitive (FDS) bryophytes. The protocol is based on (1) controlled desiccation inside Falcon tubes equilibrated at three different relative humidities that, consequently, induce three different speeds and extents of dehydration and (2) an evaluation of the average percentage of maximal photochemical efficiency of PSII (F_v/fm) recovery after rehydration. Applying the method to 10 bryophytes and 28 tracheophytes from various locations, we found that (1) imbibition of absorbent material with concentrated salt‐solutions inside the tubes provides stable relative humidity and avoids direct contact with samples; (2) for 50 ml capacity tubes, the optimal plant amount is 50–200 mg fresh weight; (3) the method is useful in remote locations due to minimal instrumental requirements; and (4) a threshold of 30% recovery of the initial F_v/fm upon reaching RWC ≤ 30% correctly categorises DT species, with three exceptions: two poikilochlorophyllous species and one gymnosperm. The protocol provides a semi‐quantitative expression of DHT that facilitates comparisons of species with different morpho‐physiological traits and/or ecological attributes.     

Helminths in the wolf, Canis lupus, from north-western Spain

Fifteen helminth species were collected from 47 wolves (Canis lupus ) which were surveyed from 1993 to 1999 in northwestern Spain. These included the trematode Alaria alata (2.1%); the cestodes Taenia hydatigena (44.7%), T. multiceps (29.8%), T. serialis (2.1%), Dipylidium caninum (6.4%) and Mesocestoides sp. aff. litteratus (4.2%); and the nematodes Pearsonema plica (7.4%), Trichuris vulpis (10.6%), Trichinella britovi (12.8%), Ancylostoma caninum (8.5%), Uncinaria stenocephala (51.1%), Toxocara canis (6.4%) Toxascaris leonina (4.2%), Angiostrongylus vasorum (2.1%) and Dirofilaria immitis (2.1%). Only two wolves were not infected. A single infection occurred in 28.9% of the cases, but the commonest infracommunity (31.1%) involved three species. The helminths Alaria alata, Taenia hydatigena, Mesocestoides sp. aff. litteratus, P. plica, Trichuris vulpis, and Ancylostoma caninum parasitizing C. lupus are reported for the first time in Spain. Taenia serialis and D. immitis are reported for the first time in wolves in Europe. Angiostrongylus vasorum represents a new host record for wolves. The helminth fauna of Spanish wolves is compared with that of other European wolf populations. Some epidemiological considerations of the helminth fauna of wolves in Spain and the health risk to humans are also discussed.     

An easy NMR method to study the formation of parallel β-sheets in peptide aggregates

There is currently great interest in the study of peptide aggregation by -sheet formation because of its relevance in pathological states or in the design of self-assembling systems of technological interest. NMR studies of -sheet aggregates are difficult because of their long correlation times and spectral degeneracy. In this communication we demonstrate the combination of a semiselective TOCSY-NOESY experiment with partial deuterium exchange of labile protons to assign inter-molecular NOE cross peaks and prove the presence of a soluble parallel -sheet in fast exchange with monomeric Ac-ASTTTNYT-NH₂ (Ac-T-NH₂) in solution.     

Preliminary studies of the 2D crystallization of Omp1 of Serratia marcescens: observation by atomic force microscopy in native membranes environment and reconstituted in proteolipid sheets

In this work the porin Omp1 of Serratia marcescens was expressed in a porin deficient mutant (Escherichia coli UH302) and its functionality studied following the accumulation of ciprofloxacin in bacteria. The protein was extracted, purified and reconstituted in proteoliposomes of different composition (lipopolysaccharide (LPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)). Maximum extraction of the detergent was achieved applying different steps of dialysis and centrifugation. Proteolipid sheets with different composition were spread onto mica and observed by atomic force microscopy. Two-dimensional crystal of Omp1 was not observed in any case due to low resolution achieved. Judging from the images features POPC is the most suitable phospholipid to enhance 2D lattice formation for Omp1.