STED nanoscopy of KK114‐stained pathogenic bacteria

Super‐resolution microscopy techniques can provide answers to still pending questions on prokaryotic organisms but are yet to be used at their full potential for this purpose. To address this, we evaluate the ability of the rhodamine‐like KK114 dye to label various types of bacteria, to enable imaging of fine structural details with stimulated emission depletion microscopy (STED). We assessed fluorescent labeling with KK114 for eleven Gram‐positive and Gram‐negative bacterial species and observed that this contrast agent binds to their cell membranes. Significant differences in the labeling outputs were noticed across the tested bacterial species, but importantly, KK114‐staining allowed the observation of subtle nanometric cell details in some cases. For example, a helix pattern resembling a cytoskeleton arrangement was detected in Bacillus subtilis. Furthermore, we found that KK114 easily penetrates the membrane of bacterial microorganism that lost their viability, which can be useful to discriminate between living and dead cells.     

Synthesis, crystal structure and magnetic properties of a 1D mixed-metal-mixed-ligand Ni(II)/Fe(II) coordination polymer built on the nitroprusside anion

A new complex [Ni(L)Fe(CN)₅NO] · 2H₂O (L = 4,6,6-trimethyl-1,9-diamino-3,7-di-aza-nona-3-ene) has been obtained and characterized by means of X-ray crystallographic analysis and magnetochemistry. The Fe(CN)₅NO²⁻ anion links to the Ni(L)²⁺ cation through two bridging cyanide groups in a bent fashion. The intrachain Ni?Ni and interchain Ni?Ni distances are equal to 9.81(8) and 7.75(1) Å, respectively. The magnetic behaviour of the complex indicates the zero field splitting parameter D higher than 3 cm⁻¹ and the average exchange parameter (intra- and interchain) corresponding to direct Ni-Ni magnetic interaction in the crystal lattice equals ∼−0.2 cm⁻¹.     

Dynamics of indirect symptoms of skeletal muscle damage after stretch-shortening exercise

Healthy untrained men (age 20.4 ± 1.7 years, n = 20) volunteered to participate in an experiment in order to establish dynamics of indirect symptoms of skeletal muscle damage (ISMD) (decrease in maximal isometric voluntary contraction torque (MVCT) and torque evoked by electrostimulation at different frequencies and at different quadriceps muscle length, height (H) of drop jump (DJ), muscle soreness and creatine kinase (CK) activity in the blood) after 100 DJs from 0.75 m height performed with maximal intensity with an interval of 20 s between the jumps (stretch-shortening exercise, SSE). All ISMDs remained even 72 h after SSE (P < 0.01–0.001). The muscle experienced greater decrease (P < 0.01) in torque evoked by electrostimulation (at low stimulation frequencies and at short muscle length in particular) after SSE than neuromuscular performance (MVCT and H of DJ) which demonstrated secondary decrease (P < 0.01) in neuromuscular performance during the first 48 h after SSE. Within 24–72 h after the SSE the subjects felt an acute muscle pain (5–7 points approximately) and the CK activity in the blood was significantly increased up to 1200 IU/L (P < 0.001). A significant correlation between decrease in MVCT and H of DJ 24–48 h after SSE on the one hand and muscle soreness registered within 24–48 h after SSE on the other was observed, whereas correlation between the other indirect symptoms of skeletal muscle damage was not significant.     

The influence of Trisenox on actin organization in HL-60 cells

The aim of this study was to show the influence of Trisenox (arsenic trioxide, ATO) on cytoplasmic and nuclear F-actin organization in HL-60 human leukemia cell line. Changes in localization were determined with the use of fluorescence microscopy and flow cytometry. Alterations, in both cytoplasmic and nuclear actin, were observed in cells exposed to ATO. F-actin network underwent accumulation and formed aggregates, that were very often placed under the cell membrane in whole cells and at the periphery of isolated nuclei. Addition of ATO also induced apoptosis and a decrease in G2 phase cells. These results suggest the influence of actin on the formation of apoptotic bodies and also participation of this protein in apoptotic alterations within nuclei, i.e. chromatin reorganization.     

Water stress injuries and tolerance as related to potassium efflux from winter rape hypocotyls

Desiccation- or immersion-induced injuries in isolated winter rape ( Brassica napus L. var. oleifera cv. Górczański) hypocotyls were highly correlated with potassium efflux and were reversible if the tissue damage was not severe (i.e. when less than 20% of electrolytes leaked from stressed tissue). The time-course of leakage of potassium and other electrolytes showed that increased membrane permeability might result from stress-induced disturbances in membrane integrity. Increased stress tolerance in hypocotyls predehydrated to a water saturation deficit of about 60% seemed to be due to stabilization of membrane structure rather than to promotion of a repair mechanism. The hardening effect of predehydration was more effective for potassium efflux than for efflux of other electrolytes.