pH gradient across the lysosomal membrane generated by selective cation permeability and Donnan equilibrium.

The pH within isolated Triton WR 1339-filled rat liver lysosomes was determined by measuring the distribution of [14C]methylamine between the intra- and extralysosomal space. The intralysosomal pH was found to be approximately one pH unit lower than that of the surrounding medium. Increasing the extralysosomal cation concentration lowered the pH gradient by a cation exchange indicating the presence of a Donnan equilibrium. The lysosomal membrane was found to be significantly more permeable to protons than to other cations. The relative mobility of cations through the lysosomal membrane is H+ greater than Cs+ greater than Rb+ greater than K greater than Na+ greater than Li+ greater than Mg2+, Ca2+. The presented data suggest that the acidity within isolated Triton WR 1339-filled lysosomes is maintained by: (1) a Donnan equilibrium resulting from the intralysosomal accumulation of nondiffusible anions and (2) a selective permeability of the lysosomal membrane to cations.     

Recovery of nitrogen fertilizer by traditional and improved rice cultivars in the Bhutan Highlands

The recovery of soil derived nitrogen (N_DFS) and fertilizer N (N_DFF) was investigated in highland rice (Oryza sativa L.) fields in Bhutan, characterized by high inputs of farmyard manure (FYM). The effect of 60 kg N ha^?1 (60 N) applied in two splits to a traditional and an improved cultivar, popular among the farmers, was investigated using the ¹⁵N isotope dilution technique. No differences were found between cultivars with respect to the uptake of N_DFS and N_DFF, but the improved cultivar yielded 27% more (P?≤?0.05) grain compared with the traditional cultivar. This was largely due to its greater harvest index (HI). The mean percentage recovery of fertilizer N (REN) applied at 45 days after transplanting (DAT) was 34% compared to 22% at 7 DAT, resulting in 56% greater uptake of N_DFF at 45 DAT. The overall REN for both the improved and the traditional cultivars were 25.7% and 30% respectively, with no difference between cultivars, but REN decreased with increasing FYM inputs. Fertilizer N recommendations that allow for previous FYM inputs combined with applications timed to coincide with maximum crop demand (45 DAT), and the use of improved cultivars, could enhance N fertilizer recoveries (REN) and increase rice yields in the Bhutan Highlands.     

Eosin staining of gelatine

Summary The mechanism of gelatine staining with four selected fluorone derivative dyes (eosin y, ethyl eosin, methyl eosin, uranin) was investigated. Gelatine films were stained in dye-buffer-ethanol solutions at varying pH and in the presence of NaCl and urea. Dye binding was recorded spectrophotometrically. Ionization constants of auxochromic phenolic groups were determined from pH-absorbance curves of dye-buffer-ethanol solutions. Dyebinding was greatest at pH below pK_OH and decreased with increasing pH. The addition of NaCl reduced dye binding slightly below pK_OH but markedly above pK_OH. The addition of 8 M urea decreased dyebinding regardless of pH. Comparing the pH dependence of dyebinding for eosin y and esterified eosins with ionization constants revealed that ionic bonding is unlikely to occur at the carboxyl group as well as at the phenolic group. Dye binding is intimately related to the presence of Br-groups. These results are discussed in conjunction with the functional structure of the dye ions and current concepts of dyebinding mechanisms.     

Innate immunity orchestrates the mobilization and homing of hematopoietic stem/progenitor cells by engaging purinergic signaling—an update

Purinergic Signalling - Bone marrow (BM) as an active hematopoietic organ is highly sensitive to changes in body microenvironments and responds to external physical stimuli from the surrounding...     

Decoupling of impact factors reveals the response of German winter wheat yields to climatic changes

Yield development of agricultural crops over time is not merely the result of genetic and agronomic factors, but also the outcome of a complex interaction between climatic and site‐specific soil conditions. However, the influence of past climatic changes on yield trends remains unclear, particularly under consideration of different soil conditions. In this study, we determine the effects of single agrometeorological factors on the evolution of German winter wheat yields between 1958 and 2015 from 298 published nitrogen (N)‐fertilization experiments. For this purpose, we separate climatic from genetic and agronomic yield effects using linear mixed effect models and estimate the climatic influence based on a coefficient of determination for these models. We found earlier occurrence of wheat growth stages, and shortened development phases except for the phase of stem elongation. Agrometeorological factors are defined as climate covariates related to the growth of winter wheat. Our results indicate a general and strong effect of agroclimatic changes on yield development, in particular due to increasing mean temperatures and heat stress events during the grain‐filling period. Except for heat stress days with more than 31°C, yields at sites with higher yield potential were less prone to adverse weather effects than at sites with lower yield potential. Our data furthermore reveal that a potential yield levelling, as found for many West‐European countries, predominantly occurred at sites with relatively low yield potential and about one decade earlier (mid‐1980s) compared to averaged yield data for the whole of Germany. Interestingly, effects related to high precipitation events were less relevant than temperature‐related effects and became relevant particularly during the vegetative growth phase. Overall, this study emphasizes the sensitivity of yield productivity to past climatic conditions, under consideration of regional differences, and underlines the necessity of finding adaptation strategies for food production under ongoing and expected climate change.     

SANS (USH1G) regulates pre-mRNA splicing by mediating the intra-nuclear transfer of tri-snRNP complexes

Splicing is catalyzed by the spliceosome, a compositionally dynamic complex assembled stepwise on pre-mRNA. We reveal links between splicing machinery components and the intrinsically disordered ciliopathy protein SANS. Pathogenic mutations in SANS/USH1G lead to Usher syndrome—the most common cause of deaf-blindness. Previously, SANS was shown to function only in the cytosol and primary cilia. Here, we have uncovered molecular links between SANS and pre-mRNA splicing catalyzed by the spliceosome in the nucleus. We show that SANS is found in Cajal bodies and nuclear speckles, where it interacts with components of spliceosomal sub-complexes such as SF3B1 and the large splicing cofactor SON but also with PRPFs and snRNAs related to the tri-snRNP complex. SANS is required for the transfer of tri-snRNPs between Cajal bodies and nuclear speckles for spliceosome assembly and may also participate in snRNP recycling back to Cajal bodies. SANS depletion alters the kinetics of spliceosome assembly, leading to accumulation of complex A. SANS deficiency and USH1G pathogenic mutations affects splicing of genes related to cell proliferation and human Usher syndrome. Thus, we provide the first evidence that splicing dysregulation may participate in the pathophysiology of Usher syndrome.     

Analysing the yeast complexome—the Complex Portal rising to the challenge

The EMBL-EBI Complex Portal is a knowledgebase of macromolecular complexes providing persistent stable identifiers. Entries are linked to literature evidence and provide details of complex membership, function, structure and complex-specific Gene Ontology annotations. Data are freely available and downloadable in HUPO-PSI community standards and missing entries can be requested for curation. In collaboration with Saccharomyces Genome Database and UniProt, the yeast complexome, a compendium of all known heteromeric assemblies from the model organism Saccharomyces cerevisiae, was curated. This expansion of knowledge and scope has led to a 50% increase in curated complexes compared to the previously published dataset, CYC2008. The yeast complexome is used as a reference resource for the analysis of complexes from large-scale experiments. Our analysis showed that genes coding for proteins in complexes tend to have more genetic interactions, are co-expressed with more genes, are more multifunctional, localize more often in the nucleus, and are more often involved in nucleic acid-related metabolic processes and processes where large machineries are the predominant functional drivers. A comparison to genetic interactions showed that about 40% of expanded co-complex pairs also have genetic interactions, suggesting strong functional links between complex members.