Vanadate and phosphate ions reduce tension and increase cross-bridge kinetics in chemically skinned heart muscle

Tension development, immediate stiffness and ATPase of chemically skinned myocardial strips were measured in solutions with varying concentrations of phosphate (Pi) or vanadate (predominantly H2VO4 at pH 7) ion. Vanadate and Pi decreased stiffness in proportion to tension. The results show that, like Pi, vanadate accelerates the turnover rate of cross-bridges, but is effective at about 1/500 the concentration required for the Pi effect. Both Pi and vanadate increased the energy cost of isometric tension maintenance (that is, the ratio of ATPase to tension) and increased the velocity of delayed tension development following quick stretch of the chemically skinned myocardial strips. The results also show that changes in the rate of rise of delayed tension during stretch activation probably reflect changes in the kinetics of the biochemical cycle of the cross-bridges.     

Interactions between soil properties,agricultural management and cultivar type drive structural and functional adaptations of the wheat rhizosphere microbiome to drought

Rhizosphere microbial communities adapt their structural and functional compositions to water scarcity and have the potential to substantially mitigate drought stress of crops. To unlock this potential, it is crucial to understand community responses to drought in the complex interplay between soil properties, agricultural management and crop species. Two winter wheat cultivars, demanding and non-demanding, were exposed to drought stress in loamy Chernozem and sandy Luvisol soils under conventional or organic farming management. Structural and functional adaptations of the rhizosphere bacteria were assessed by 16S amplicon sequencing, the predicted abundance of drought-related functional genes in the bacterial community based on 16S amplicon sequences (Tax4Fun) and the activity potentials of extracellular enzymes involved in the carbon cycle. Bacterial community composition was strongly driven by drought and soil type. Under drought conditions, Gram-positive phyla became relatively more abundant, but either less or more diverse in Luvisol and Chernozem soil respectively. Enzyme activities and functional gene abundances related to carbon degradation were increased under drought in the rhizosphere of the demanding wheat cultivar in organic farming. We demonstrate that soil type, farming system and wheat cultivar each constitute important factors during the structural and/or functional adaptation of rhizobacterial communities in response to drought.     

Über Nebenkerne,Basalfilamente, Kristalloide und ähnliche Gebilde im Plasma verschiedener Zellen

Ohne Zusammenfassung     

Oxalate Extraction of Pb and Zn from Polluted Soils: Solubility Limitations

Oxalate (Ox) was used to extract Pb and Zn from industrially contaminated soils. Although Ox effectively releases metals bound by hydrous oxide soil components, it forms insoluble salts with some heavy metals unlike conventional extractants (e.g., EDTA). The insolubility of PbOx(s) (K_sp=2.74 × 10^?11) precluded the use of Ox as a single-step extractant even for soils mildly contaminated with Pb. The usefulness of Ox as a Zn extractant, however, depends on the level of soil contamination. A Zn solubility model, based on published equilibrium constants, was developed to assess Ox suitability as a function of system conditions. Precipitation of ZnOx(s) hindered Zn recovery under acidic conditions where formation of soluble oxalato complexes was small. For pH<3, the presence of 1?M Ox actually reduced Zn release compared to simple acid washing. Although Ox displaces oxide-bound metals and thus is potentially useful in soil washing, solubility limitations must be defined for effective remediation of metal-laden soils.     

Correlative 3D‐imaging of Pipistrellus penis micromorphology: Validating quantitative microCT images with undecalcified serial ground section histomorphology

Detailed knowledge of histomorphology is a prerequisite for the understanding of function, variation, and development. In bats, as in other mammals, penis and baculum morphology are important in species discrimination and phylogenetic studies. In this study, nondestructive 3D‐microtomographic (microCT, µCT) images of bacula and iodine‐stained penes of Pipistrellus pipistrellus were correlated with light microscopic images from undecalcified surface‐stained ground sections of three of these penes of P. pipistrellus (1 juvenile). The results were then compared with µCT‐images of bacula of P. pygmaeus, P. hanaki, and P. nathusii. The Y‐shaped baculum in all studied Pipistrellus species has a proximal base with two club‐shaped branches, a long slender shaft, and a forked distal tip. The branches contain a medullary cavity of variable size, which tapers into a central canal of variable length in the proximal baculum shaft. Both are surrounded by a lamellar and a woven bone layer and contain fatty marrow and blood vessels. The distal shaft consists of woven bone only, without a vascular canal. The proximal ends of the branches are connected with the tunica albuginea of the corpora cavernosa via entheses. In the penis shaft, the corpus spongiosum‐surrounded urethra lies in a ventral grove of the corpora cavernosa, and continues in the glans under the baculum. The glans penis predominantly comprises an enlarged corpus spongiosum, which surrounds urethra and baculum. In the 12 studied juvenile and subadult P. pipistrellus specimens the proximal branches of the baculum were shorter and without marrow cavity, while shaft and distal tip appeared already fully developed. The present combination with light microscopic images from one species enabled a more reliable interpretation of histomorphological structures in the µCT‐images from all four Pipistrellus species. J. Morphol. 276:695–706, 2015. © 2015 Wiley Periodicals, Inc.     

Single-Channel Resolution of the Interaction between C-Terminal CaV1.3 Isoforms and Calmodulin

Voltage-dependent calcium (Ca_V) 1.3 channels are involved in the control of cellular excitability and pacemaking in neuronal, cardiac, and sensory cells. Various proteins interact with the alternatively spliced channel C-terminus regulating gating of Ca_V1.3 channels. Binding of a regulatory calcium-binding protein calmodulin (CaM) to the proximal C-terminus leads to the boosting of channel activity and promotes calcium-dependent inactivation (CDI). The C-terminal modulator domain (CTM) of Ca_V1.3 channels can interfere with the CaM binding, thereby inhibiting channel activity and CDI. Here, we compared single-channel gating behavior of two natural Ca_V1.3 splice isoforms: the long Ca_V1.3₄₂ with the full-length CTM and the short Ca_V1.3_42A with the C-terminus truncated before the CTM. We found that CaM regulation of Ca_V1.3 channels is dynamic on a minute timescale. We observed that at equilibrium, single Ca_V1.3₄₂ channels occasionally switched from low to high open probability, which perhaps reflects occasional binding of CaM despite the presence of CTM. Similarly, when the amount of the available CaM in the cell was reduced, the short Ca_V1.3_42A isoform showed patterns of the low channel activity. CDI also underwent periodic changes with corresponding kinetics in both isoforms. Our results suggest that the competition between CTM and CaM is influenced by calcium, allowing further fine-tuning of Ca_V1.3 channel activity for particular cellular needs.