Photobiont selectivity and specificity in Caloplaca species in a fog-induced community in the Atacama Desert, northern Chile

Little is known about the nature of the association between mycobionts and photobionts in isolated lichen communities. Here we studied the photobiont diversity of different Caloplaca species in a fog-induced community in the Atacama Desert. We compared nrDNA ITS sequences of both symbionts, photobionts and mycobionts, along with morphological characters of the different lichen thalli, to investigate the diversity and to assess the degree of selectivity and specificity of photobiont species in a community of Caloplaca species. Specimens of six fungal species (C. orthoclada, C. fernandeziana, and four undescribed species) were sampled along an altitudinal gradient on a coastal bluff with a strong fog presence, 60 km south of Iquique, Chile. The photobiont species in this community belong to three species of the genus Trebouxia in the strict sense: T. arboricola, T. decolorans, and T. gigantea. Most of the fungal species were lichenized with photobionts belonging to different haplotypes of T. arboricola and T. decolorans, although the algae of three specimens, associated with two fungal species (C. orthoclada and C. sp1), were related to representatives of T. gigantea. These results indicate that members of the genus Caloplaca in northern Chile have moderate photobiont selectivity and appear to be selective to members of the T. arboricola group. Also, at high altitudes, changes in the photobiontal haplotype composition were observed in comparison to lower altitudes, probably generated by a higher water availability given higher fog condensation and precipitation in the upper areas of the bluff. This may suggest that ecological factors, such as altitude and water availability could result in a local shift of the associated photobiont and specialization as a product of local adaptation.     

Coupling of fully automated chip-based electrospray ionization to high-capacity ion trap mass spectrometer for ganglioside analysis

NanoMate robot was coupled to a high-capacity ion trap (HCT) mass spectrometer to create a system merging automatic chip-based electrospray ionization (ESI) infusion, ultrafast ion detection, and multistage sequencing at superior sensitivity. The interface between the NanoMate and HCT mass spectrometer consists of an in-laboratory constructed mounting device that allows adjustment of the robot position with respect to the mass spectrometer inlet. The coupling was optimized for ganglioside (GG) high-throughput analysis in the negative ion mode and was implemented in clinical glycolipidomics for identification and structural characterization of anencephaly-associated species. By NanoMate HCT mass spectrometry (MS), data corroborating significant differences in GG expression in anencephalic versus age-matched normal brain tissue were collected. The feasibility of chip-based nanoESI HCT multistage collision-induced dissociation (CID MSⁿ) for polysialylated GG fragmentation and isomer discrimination was tested on a GT1 (d18:1/18:0) anencephaly-associated structure. MS²-MS⁴ obtained by accumulating scans at variable fragmentation amplitudes gave rise to the first fragmentation patterns from which the presence of GT1b structural isomer could be determined unequivocally without the need for supplementary investigation by any other analytical or biochemical methods.     

Anthraquinones from in vitro root culture of <Emphasis Type="Italic">Morinda royoc</Emphasis> L.

Morinda royoc L. (Rubiaceae) root cultures were established for the production of anthraquinones (AQs). Three independent experiments were performed to evaluate the effects of different levels of indole-3-acetic acid (0–22.8 μM), culture duration (15–75 days) and subculture number (0–4). The following indicators were recorded: root fresh weight per Erlenmeyer and intracellular and extracellular AQ production. The experiments performed in this study allowed an increase of intracellular AQ content up to a maximum of 4.5 mg g⁻¹ of fresh mass, after 30 days of culture in a medium 5.7 μM of IAA. In addition, isolation and identification of seven AQs from M. royoc L. roots is described, one of them being reported for the first time for this species. The structures of isolated compounds were determined from ¹H-NMR data. To the best of our knowledge, this is the first report on AQ production from root culture of this plant.     

Morphometry of the midgut epithelium of Diatraea saccharalis Fabricius, 1794 (Lepidoptera) parasitized by Cotesia flavipes Cameron, 1891 (Hymenoptera)

The morphometric study of the midgut in Diatraea saccharalis (Lepidoptera) larvae parasitized by the Cotesia flavipes (Hymenoptera) showed that there was significant increase in the columnar, goblet and regenerative cells and their nuclei; the midgut lumen diameter and the epithelial height were also increased in the parasitized larvae. The multivariate analysis showed that parasitism affected the columnar cell only in the posterior region, and the goblet cells along the midgut length (anterior and posterior regions).     

Complementary pathways of dissolved organic carbon removal pathways in clear-water Amazonian ecosystems: photochemical degradation and bacterial uptake

Dissolved organic carbon (DOC) photochemical reactions establish important links between DOC and planktonic bacteria. We hypothesize that seasonal changes in DOC quality, related to the flood pulse, drive the effects of light-DOC interactions on uptake by planktonic bacteria uptake in clear-water Amazonian ecosystems. Water samples from two ecosystems (one lake and one stream) were incubated in sunlight during different hydrological periods and were then exposed to bacterial degradation. Photochemical and bacterial degradation were driven by seasonal DOC inputs. Bacterial mineralization was the main degradation pathway of autochthonous DOC in the lake, while allochthonous DOC was more available for photochemical oxidation. We suggest that sunlight enhances the bacterial uptake of refractory DOC but does not alter uptake of labile forms. We also observed a positive relationship between sunlight and bacterial degradation of DOC, instead of competition. We conclude that photochemical reactions and bacteria complementarily degrade the different sources of DOC during the flood pulse in Amazonian clear-water aquatic ecosystems.     

NMR structures and molecular dynamics simulation of hylin‐a1 peptide analogs interacting with micelles

Antimicrobial peptides are recognized candidates with pharmaceutical potential against epidemic emerging multi‐drug resistant bacteria. In this study, we use nuclear magnetic resonance spectroscopy and molecular dynamics simulations to determine the unknown structure and evaluate the interaction with dodecylphosphatidylcholine (DPC) and sodium dodecylsulphate (SDS) micelles with three W⁶‐Hylin‐a1 analogs antimicrobial peptides (HyAc, HyK, and HyD). The HyAc, HyK, and HyD bound to DPC micelles are all formed by a unique α‐helix structure. Moreover, all peptides reach the DPC micelles' core, which thus suggests that the N‐terminal modifications do not influence the interaction with zwiterionic surfaces. On the other hand, only HyAc and HyK peptides are able to penetrate the SDS micelle core while HyD remains always at its surface. The stability of the α‐helical structure, after peptide‐membrane interaction, can also be important to the second step of peptide insertion into the membrane hydrophobic core during permeabilization. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

A 4.2 kDa synthetic peptide as a potential probe to evaluate the antibacterial activity of coumarin drugs.

The coumarin antibiotics are potent inhibitors of DNA replication whose target is the enzyme DNA gyrase, an ATP-dependent bacterial type II topoisomerase. The coumarin drugs inhibit gyrase action by competitive binding to the ATP-binding site of DNA gyrase B protein. The production of new biologically active products has stimulated additional studies on coumarin-gyrase interactions. In this regard, a 4.2 kDa peptide mimic of DNA gyrase B protein from Escherichia coli has been designed and synthesized. The peptide sequence includes the natural fragment 131-146 (coumarin resistance-determining region) and a segment containing the gyrase-DNA interaction region (positions 753-770). The peptide mimic binds to novobiocin (Ka = 1.4+/-0.3 x 10(5) M(-1)), plasmid (Ka = 1.6+/-0.5 x 10(6) M(-1)) and ATP (Ka = 1.9+/-50.4 x 10(3) M(-1)), results previously found with the intact B protein. On the other hand, the binding to novobiocin was reduced when a mutation of Arg-136 to Leu-136 was introduced, a change previously found in the DNA gyrase B protein from several coumarin-resistant clinical isolates of Escherichia coli In contrast, the binding to plasmid and to ATP was not altered. These results suggest that synthetic peptides designed in a similar way to that described here could be used as mimics of DNA gyrase in studies which seek a better understanding of the ATP, as well as coumarin, binding to the gyrase and also the mechanism of action of this class of antibacterial drugs.     

Calcium Efflux from Internally Dialyzed Squid Giant Axons

Calcium efflux has been studied in squid giant axons under conditions in which the internal composition was controlled by means of a dialysis perfusion technique. The mean calcium efflux from axons dialyzed with 0.3 µM calcium and 5 mM ATP was 0.26 pmol/cm²·s at 22°C. The curve relating the Ca efflux with the internal Ca concentration had a slope of about one for [Ca]_i lower than 0.3µM and a slope smaller than one for higher concentrations. Under the above conditions replacement of [Na]_o and [Ca]_o by Tris and Mg causes an 80% fall in the calcium efflux. When the axons were dialyzed with a medium free of ATP and containing 2 mM cyanide plus 5µg/ml oligomycin, analysis of the perfusion effluent gave values of 1–4 µM ATP. Under this low ATP condition, replacement of external sodium and calcium causes the same drop in the calcium efflux. The same effect was observed at higher [Ca]_i, (80 µM). These results suggest that the Na-Ca exchange component of the calcium efflux is apparently not dependent on the amounts of ATP in the axoplasm. Axons previously depleted of ATP show a significant transient drop in the calcium efflux when ATP is added to the dialysis medium. This effect probably represents the sequestering of calcium by the mitochondrial system. The consumption of calcium by the mitochondria of the axoplasm in dialyzed axons was determined to be of the order of 6.0 x 10^-7 mol Ca⁺⁺/mg of protein with an initial rate of 2.6 x 10^-8 mol Ca⁺⁺/min·mg of protein. Axons dialyzed with 2 mM cyanide after 8–10-min delays show a rise in the calcium efflux in the presence of "normal" amounts of exogenous ATP. This effect seems to indicate that cyanide, per se, can release calcium ions from internal sources.     

A rapid and efficient method for purifying high quality total RNA from peaches (Prunus persica) for functional genomics analyses

Prunus persica has been proposed as a genomic model for deciduous trees and the Rosaceae family. Optimized protocols for RNA isolation are necessary to further advance studies in this model species such that functional genomics analyses may be performed. Here we present an optimized protocol to rapidly and efficiently purify high quality total RNA from peach fruits (Prunus persica). Isolating high-quality RNA from fruit tissue is often difficult due to large quantities of polysaccharides and polyphenolic compounds that accumulate in this tissue and co-purify with the RNA. Here we demonstrate that a modified version of the method used to isolate RNA from pine trees and the woody plant Cinnamomun tenuipilum is ideal for isolating high quality RNA from the fruits of Prunus persica. This RNA may be used for many functional genomic based experiments such as RT-PCR and the construction of large-insert cDNA libraries.