Spatio-temporal mapping of local soil pH changes induced by roots of lupin and soft-rush

Aims

The rhizosphere is a dynamic system strongly influenced by root activity. Roots modify the pH of their surrounding soil causing the soil pH to vary as a function of distance from root surface, location along root axes, and root maturity. Non-invasive imaging techniques provide the possibility to capture pH patterns around the roots as they develop.

Methods

We developed a novel fluorescence imaging set up and applied to the root system of two lupin (Lupinus albus L., Lupinus angustifolius L.) and one soft-rush (Juncus effusus L.) species. We grew plants in glass containers filled with soil and equipped with fluorescence sensor foils on the container side walls. We gained highly-resolved data on the spatial distribution of H⁺ around the roots by taking time-lapse images of the samples over the course of several days.

Results

We showed how the soil pH in the vicinity of roots developed over time to different values from that of the original bulk soil. The soil pH in the immediate vicinity of the root surface varied greatly along the root length, with the most acidic point being at 0.56–3.36 mm behind the root tip. Indications were also found for temporal soil pH changes due to root maturity.

Conclusion

In conclusion, this study shows that this novel optical fluorescence imaging set up is a powerful tool for studying pH developments around roots in situ.     

Phosphorylation of Serine 1137/1138 of Mouse Insulin Receptor Substrate (IRS) 2 Regulates cAMP-dependent Binding to 14-3-3 Proteins and IRS2 Protein Degradation

Insulin receptor substrate (IRS) 2 as intermediate docking platform transduces the insulin/IGF-1 (insulin like growth factor 1) signal to intracellular effector molecules that regulate glucose homeostasis, β-cell growth, and survival. Previously, IRS2 has been identified as a 14-3-3 interaction protein. 14-3-3 proteins can bind their target proteins via phosphorylated serine/threonine residues located within distinct motifs. In this study the binding of 14-3-3 to IRS2 upon stimulation with forskolin or the cAMP analog 8-(4-chlorophenylthio)-cAMP was demonstrated in HEK293 cells. Binding was reduced with PKA inhibitors H89 or R_p-8-Br-cAMPS. Phosphorylation of IRS2 on PKA consensus motifs was induced by forskolin and the PKA activator N⁶-Phe-cAMP and prevented by both PKA inhibitors. The amino acid region after position 952 on IRS2 was identified as the 14-3-3 binding region by GST-14-3-3 pulldown assays. Mass spectrometric analysis revealed serine 1137 and serine 1138 as cAMP-dependent, potential PKA phosphorylation sites. Mutation of serine 1137/1138 to alanine strongly reduced the cAMP-dependent 14-3-3 binding. Application of cycloheximide revealed that forskolin enhanced IRS2 protein stability in HEK293 cells stably expressing IRS2 as well as in primary hepatocytes. Stimulation with forskolin did not increase protein stability either in the presence of a 14-3-3 antagonist or in the double 1137/1138 alanine mutant. Thus the reduced IRS2 protein degradation was dependent on the interaction with 14-3-3 proteins and the presence of serine 1137/1138. We present serine 1137/1138 as novel cAMP-dependent phosphorylation sites on IRS2 and show their importance in 14-3-3 binding and IRS2 protein stability.     

Distinct population structure for co-occurring Anopheles goeldii and Anopheles triannulatus in Amazonian Brazil

To evaluate whether environmental heterogeneity contributes to the genetic heterogeneity in Anopheles triannulatus, larval habitat characteristics across the Brazilian states of Roraima and Pará and genetic sequences were examined. A comparison with Anopheles goeldii was utilised to determine whether high genetic diversity was unique to An. triannulatus. Student t test and analysis of variance found no differences in habitat characteristics between the species. Analysis of population structure of An. triannulatus and An. goeldii revealed distinct demographic histories in a largely overlapping geographic range. Cytochrome oxidase I sequence parsimony networks found geographic clustering for both species; however nuclear marker networks depicted An. triannulatus with a more complex history of fragmentation, secondary contact and recent divergence. Evidence of Pleistocene expansions suggests both species are more likely to be genetically structured by geographic and ecological barriers than demography. We hypothesise that niche partitioning is a driving force for diversity, particularly in An. triannulatus.     

Mutations in BICD2, which Encodes a Golgin and Important Motor Adaptor,Cause Congenital Autosomal-Dominant Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a heterogeneous group of neuromuscular disorders caused by degeneration of lower motor neurons. Although functional loss of SMN1 is associated with autosomal-recessive childhood SMA, the genetic cause for most families affected by dominantly inherited SMA is unknown. Here, we identified pathogenic variants in bicaudal D homolog 2 (Drosophila) (BICD2) in three families afflicted with autosomal-dominant SMA. Affected individuals displayed congenital slowly progressive muscle weakness mainly of the lower limbs and congenital contractures. In a large Dutch family, linkage analysis identified a 9q22.3 locus in which exome sequencing uncovered c.320C>T (p.Ser107Leu) in BICD2. Sequencing of 23 additional families affected by dominant SMA led to the identification of pathogenic variants in one family from Canada (c.2108C>T [p.Thr703Met]) and one from the Netherlands (c.563A>C [p.Asn188Thr]). BICD2 is a golgin and motor-adaptor protein involved in Golgi dynamics and vesicular and mRNA transport. Transient transfection of HeLa cells with all three mutant BICD2 cDNAs caused massive Golgi fragmentation. This observation was even more prominent in primary fibroblasts from an individual harboring c.2108C>T (p.Thr703Met) (affecting the C-terminal coiled-coil domain) and slightly less evident in individuals with c.563A>C (p.Asn188Thr) (affecting the N-terminal coiled-coil domain). Furthermore, BICD2 levels were reduced in affected individuals and trapped within the fragmented Golgi. Previous studies have shown that Drosophila mutant BicD causes reduced larvae locomotion by impaired clathrin-mediated synaptic endocytosis in neuromuscular junctions. These data emphasize the relevance of BICD2 in synaptic-vesicle recycling and support the conclusion that BICD2 mutations cause congenital slowly progressive dominant SMA.     

Protein conformational exchange measured by 1H R1ρ relaxation dispersion of methyl groups

Activated dynamics plays a central role in protein function, where transitions between distinct conformations often underlie the switching between active and inactive states. The characteristic time scales of these transitions typically fall in the microsecond to millisecond range, which is amenable to investigations by NMR relaxation dispersion experiments. Processes at the faster end of this range are more challenging to study, because higher RF field strengths are required to achieve refocusing of the exchanging magnetization. Here we describe a rotating-frame relaxation dispersion experiment for ¹H spins in methyl ¹³CHD₂ groups, which improves the characterization of fast exchange processes. The influence of ¹H–¹H rotating-frame nuclear Overhauser effects (ROE) is shown to be negligible, based on a comparison of R _1ρ relaxation data acquired with tilt angles of 90° and 35°, in which the ROE is maximal and minimal, respectively, and on samples containing different ¹H densities surrounding the monitored methyl groups. The method was applied to ubiquitin and the apo form of calmodulin. We find that ubiquitin does not exhibit any ¹H relaxation dispersion of its methyl groups at 10 or 25 °C. By contrast, calmodulin shows significant conformational exchange of the methionine methyl groups in its C-terminal domain, as previously demonstrated by ¹H and ¹³C CPMG experiments. The present R _1ρ experiment extends the relaxation dispersion profile towards higher refocusing frequencies, which improves the definition of the exchange correlation time, compared to previous results.     

Antioxidant efficacy and adhesion rescue by a recombinant mussel foot protein‐6

Mytilus foot protein type 6 (mfp‐6) is crucial for maintaining the reducing conditions needed for optimal wet adhesion in marine mussels. In this report, we describe the expression and production of a recombinant Mytilus californianus foot protein type 6 variant 1 (rmfp‐6.1) fused with a hexahistidine affinity tag in Escherichia coli and its purification by affinity chromatography. Recombinant mfp‐6 showed high purification yields of 5–6 mg L^?1 cell culture and excellent solubility in low pH buffers that retard oxidation of its many thiol groups. Purified rmfp‐6.1 protein showed high 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity when compared with vitamin C. Using the highly sensitive surface forces apparatus (SFA) technique to measure interfacial surface forces in the nano‐Newton range, we show that rmfp‐6.1 is also able to rescue the oxidation‐dependent adhesion loss of mussel foot protein 3 (mfp‐3) at pH 3. The adhesion rescue is related to a reduction of dopaquinone back to 3,4‐dihydroxyphenyl‐l ‐alanine in mfp‐3, which is the reverse reaction observed during the detrimental enzymatic browning process in fruits and vegetables. Broadly viewed, rmfp‐6.1 has potential as a versatile antioxidant for applications ranging from personal products to antispoilants for perishable foods during processing and storage. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1587–1593, 2013     

Affective Computing and the Impact of Gender and Age

Affective computing aims at the detection of users’ mental states, in particular, emotions and dispositions during human-computer interactions. Detection can be achieved by measuring multimodal signals, namely, speech, facial expressions and/or psychobiology. Over the past years, one major approach was to identify the best features for each signal using different classification methods. Although this is of high priority, other subject-specific variables should not be neglected. In our study, we analyzed the effect of gender, age, personality and gender roles on the extracted psychobiological features (derived from skin conductance level, facial electromyography and heart rate variability) as well as the influence on the classification results. In an experimental human-computer interaction, five different affective states with picture material from the International Affective Picture System and ULM pictures were induced. A total of 127 subjects participated in the study. Among all potentially influencing variables (gender has been reported to be influential), age was the only variable that correlated significantly with psychobiological responses. In summary, the conducted classification processes resulted in 20% classification accuracy differences according to age and gender, especially when comparing the neutral condition with four other affective states. We suggest taking age and gender specifically into account for future studies in affective computing, as these may lead to an improvement of emotion recognition accuracy.     

Closed-Cell Stent-Assisted Coiling of Intracranial Aneurysms: Evaluation of Changes in Vascular Geometry Using Digital Subtraction Angiography

BackgroundStent-assisted coil embolization (SACE) plays an important role in the treatment of intracranial aneurysms. The purpose of this study was to investigate geometrical changes caused by closed-cell design stents in bifurcation and sidewall aneurysms.Methods31 patients with 34 aneurysms underwent SACE with closed-cell design stents. Inflow angle α, determined by aneurysm neck and afferent vessel, and angle between afferent and efferent vessel close to (δ₁), respectively, more remote from the aneurysm neck (δ₂) were graphically determined in 2D angiography projections.ResultsStent assisted coiling resulted in a significant increase of all three angles from a mean value (±SEM) of α = 119° (±6.5°) pretreatment to 130° (±6.6°) posttreatment (P ≤ .001), δ₁ = 129° (±6.4°) to 139° (±6.1°), (P ≤ .001) and δ₂ = 115° (±8.4°) to 126° (±7.5°), (P ≤ .01). Angular change of δ₁ in AcomA aneurysms was significant greater compared to sidewall aneurysms (26°±4.9° versus 8°± 2.3°, P ≤ .05). The initial angle of δ₁ and δ₂ revealed a significantly inverse relationship to the angle increase (δ₁: r = -0.41, P ≤ .05 and δ₂: r = -0.47, P ≤ .01). Moreover, angle δ₁ was significantly higher in unruptured compared to ruptured aneurysms (135°±7.1° versus 103°±10.8°, P ≤ .05).ConclusionStent deployment modulates the geometry of the aneurysm-vessel complex, which may lead to favorable hemodynamic changes more similar to unruptured than to ruptured aneurysms. Our findings also suggest that the more acute-angled aneurysm-vessel anatomy, the larger the angular change. Further studies are needed to investigate whether these changes improve the clinical outcome.