High-throughput metal susceptibility testing of microbial biofilms

BACKGROUND: Microbial biofilms exist all over the natural world, a distribution that is paralleled by metal cations and oxyanions. Despite this reality, very few studies have examined how biofilms withstand exposure to these toxic compounds. This article describes a batch culture technique for biofilm and planktonic cell metal susceptibility testing using the MBEC assay. This device is compatible with standard 96-well microtiter plate technology. As part of this method, a two part, metal specific neutralization protocol is summarized. This procedure minimizes residual biological toxicity arising from the carry-over of metals from challenge to recovery media. Neutralization consists of treating cultures with a chemical compound known to react with or to chelate the metal. Treated cultures are plated onto rich agar to allow metal complexes to diffuse into the recovery medium while bacteria remain on top to recover. Two difficulties associated with metal susceptibility testing were the focus of two applications of this technique. First, assays were calibrated to allow comparisons of the susceptibility of different organisms to metals. Second, the effects of exposure time and growth medium composition on the susceptibility of E. coli JM109 biofilms to metals were investigated. RESULTS: This high-throughput method generated 96-statistically equivalent biofilms in a single device and thus allowed for comparative and combinatorial experiments of media, microbial strains, exposure times and metals. By adjusting growth conditions, it was possible to examine biofilms of different microorganisms that had similar cell densities. In one example, Pseudomonas aeruginosa ATCC 27853 was up to 80 times more resistant to heavy metalloid oxyanions than Escherichia coli TG1. Further, biofilms were up to 133 times more tolerant to tellurite (TeO(3)(2-)) than corresponding planktonic cultures. Regardless of the growth medium, the tolerance of biofilm and planktonic cell E. coli JM109 to metals was time-dependent. CONCLUSION: This method results in accurate, easily reproducible comparisons between the susceptibility of planktonic cells and biofilms to metals. Further, it was possible to make direct comparisons of the ability of different microbial strains to withstand metal toxicity. The data presented here also indicate that exposure time is an important variable in metal susceptibility testing of bacteria

AN EMG PROFILE OF LOWER LIMB MUSCLES DURING LINEAR GLIDE AND STANDING SHOT PUTTING

The purpose of this study was to provide a descriptive analysis of the phasic muscle activity of 8 lower limb muscles during performance of the shot put field event in track and field athletics. Six shot putters performed 3 standing and 3 full linear glide technique throws. Electromyography (EMG) of 8 lower limb muscles was recorded during the trials and the distance thrown was also measured. A comparison between standing and glide techniques are important from a coaching perspective. An increase in peak muscle activity of the Rectus Femoris was observed between the glide and standing throw, all other lower limb muscles showed no significant increases between the techniques. Results show significant increases between performances of standing and glide throws in female athletes however the mean differences were smaller in the male athletes

A METHOD COMPARISON OF FORCE PLATFORM AND ACCELEROMETER MEASURES IN JUMPING

The purpose of this study was to compare force calculated using accelerometer data from the SHIMMER device, with force platform data on countermovement and drop jumps. Twelve physically active adults performed 5 counter movement jumps and 5 drop jumps from a height of 0.30 m. An accelerometer was attached near the participant’s centre of mass and simultaneous force and acceleration data were obtained for the jumps. Minimum eccentric force and peak concentric force were calculated concurrently for countermovement jumps and peak landing forces were calculated concurrently for drop jumps. The results showed moderate to poor levels of agreement in forces and a consistent systematic bias between the results from the force platform and accelerometer

A COMPARSION OF METHODS TO EXAMINE DOUBLE AND SINGLE LEG DROP JUMP PERFORMANCE

The purpose of this study was to compare the use of both a force platform and Optojump photocell system (Microgate, Bolzano, Italy) to examine double leg and single leg drop jumps. Thirteen physically active individuals performed 5 double leg drop jumps and 5 single leg drop jumps from a height of 0.3 m. Ground contact time (CT), flight height (FH) and reactive strength index (RSI) were calculated concurrently for both jump types. Despite intraclass correlation coefficients for all variables being very close to 1, a significant systematic difference was consistently observed between both devices with the Optojump system overestimating CT and underestimating both FH and RSI for both jump types. Both devices demonstrated excellent test- retest reliability with all ICCs for CT, FH and RSI above 0.940

Plasma microRNA levels following resection of metastatic melanoma

Melanoma remains the leading cause of skin cancer–related deaths. Surgical resection and adjuvant therapies can result in disease-free intervals for stage III and stage IV disease; however, recurrence is common. Understanding microRNA (miR) dynamics following surgical resection of melanomas is critical to accurately interpret miR changes suggestive of melanoma recurrence. Plasma of 6 patients with stage III (n = 2) and stage IV (n = 4) melanoma was evaluated using the NanoString platform to determine pre- and postsurgical miR expression profiles, enabling analysis of more than 800 miRs simultaneously in 12 samples. Principal component analysis detected underlying patterns of miR expression between pre- vs postsurgical patients. Group A contained 3 of 4 patients with stage IV disease (pre- and postsurgical samples) and 2 patients with stage III disease (postsurgical samples only). The corresponding preoperative samples to both individuals with stage III disease were contained in group B along with 1 individual with stage IV disease (pre- and postsurgical samples). Group A was distinguished from group B by statistically significant analysis of variance changes in miR expression ( P < .0001). This analysis revealed that group A vs group B had downregulation of let-7b-5p, miR-520f, miR-720, miR-4454, miR-21-5p, miR-22-3p, miR-151a-3p, miR-378e, and miR-1283 and upregulation of miR-126-3p, miR-223-3p, miR-451a, let-7a-5p, let-7g-5p, miR-15b-5p, miR-16-5p, miR-20a-5p, miR-20b-5p, miR-23a-3p, miR-26a-5p, miR-106a-5p, miR-17-5p, miR-130a-3p, miR-142-3p, miR-150-5p, miR-191-5p, miR-199a-3p, miR-199b-3p, and miR-1976. Changes in miR expression were not readily evident in individuals with distant metastatic disease (stage IV) as these individuals may have prolonged inflammatory responses. Thus, inflammatory-driven miRs coinciding with tumor-derived miRs can blunt anticipated changes in expression profiles following surgical resection

Group-theoretical analysis of structural instability, vacancy ordering and magnetic transitions in the system troilite (FeS)-pyrrhotite (Fe<inf>1-x</inf>S)

© International Union of Crystallography 2019. A group-theoretical framework to describe vacancy ordering and magnetism in the Fe 1-x S system is developed. This framework is used to determine the sequence of crystal structures consistent with the observed magnetic structures of troilite (FeS), and to determine the crystallographic nature of the low-temperature Besnus transition in Fe 0.875 S. It is concluded that the Besnus transition is a magnetically driven transition characterized by the rotation of the moments out of the crystallographic plane to which they are confined above the transition, accompanied by small atomic displacements that lower the symmetry from monoclinic to triclinic at low temperatures. Based on the phase diagram, magnetically driven phase transitions at low temperatures are predicted in all the commensurate superstructures of pyrrhotite. Based on the phase diagram, magnetically driven spin reorientations at low temperatures are predicted in all the commensurate superstructures of pyrrhotite. The exact nature of the spin rotation is determined by the symmetry of the vacancy-ordered state and based on this spin-flop transitions in 3C and 5C pyrrhotite and a continuous rotation akin to that seen in 4C pyrrhotite are predicted. A Besnus-type transition is also possible in 6C pyrrhotite. Furthermore, it is clarified that 3C and 4C pyrrhotite carry a ferrimagnetic moment whereas 5C and 6C are antiferromagnetic

What is the true nature of blinkers?

Aims. The aim of this work is to identify the true nature of the transient EUV brightenings, called blinkers. Methods. Co-spatial and co-temporal multi-instrument data, including imaging (EUVI/STEREO, XRT and SOT/Hinode), spectroscopic (CDS/SoHO and EIS/Hinode) and magnetogram (SOT/Hinode) data, of an isolated equatorial coronal hole were used. An automatic program for identifying transient brightenings in CDS O v 629 Å, EUVI 171 Å and XRT was applied. Results. We identified 28 blinker groups in the CDS O v 629 Å raster images. All CDS O v 629 Å blinkers showed counterparts in EUVI 171 Å and 304 Å images. We classified these blinkers into two categories, one associated with coronal counterparts and other with no coronal counterparts as seen in XRT images and EIS Fe xii 195.12 Å raster images. Around two-thirds of the blinkers show coronal counterparts and correspond to various events like EUV/X-ray jets, brightenings in coronal bright points or foot-point brightenings of larger loops. These brightenings occur repetitively and have a lifetime of around 40 min at transition region temperatures. The remaining blinker groups with no coronal counterpart in XRT and EIS Fe xii 195.12 Å appear as point-like brightenings and have chromospheric/transition region origin. They take place only once and have a lifetime of around 20 min. In general, lifetimes of blinkers are different at different wavelengths, i.e. different temperatures, decreasing from the chromosphere to the corona. Conclusions. This work shows that the term blinker covers a range of phenomena. Blinkers are the EUV response of various transient events originating at coronal, transition region and chromospheric heights. Hence, events associated with blinkers contribute to the formation and maintenance of the temperature gradient in the transition region and the corona