On chip optofluidic low-pressure monitoring device

We present an on chip optofluidic surface deformable liquid Dove prism (LDP) based low-fluid flow pressure monitoring device. The unique design of the device in combination with liquid and soft solid enabled by the total internal reflection of light makes the sensor highly sensitive and compatible with the integration of a microfluidic and/or Lab-on-a-chip device. A layer-by-layer soft lithographic (LSL) and 3D printing technique are exploited to make the device. We have used Polydimethylsiloxane (PDMS) as the layer material and two variety of liquids (a) immersion oil (IO) and (b) di-iodomethane (DI) as refracting medium to construct the LDP sensor. Optical ray tracing simulation is performed to optimize the sensor. The pressure sensor shows sensitivity as high as ±28.5 mV per 50 Pa pressure with an error ± 2.5 mV and repeatability of ~99.56% at full scale. We have shown the applicability of the sensor by capturing and analyzing respiratory pressure signals of some human subjects at numerous conditions.     

Pheromone monitoring in the field using single sensillum recording

In order to obtain direct information of stimulus dynamics perceived by a male moth under field conditions a portable device was constructed which enables continuous recording of responses from individual pheromone receptors. The device is suitable for tip recording by means of micro-knives as well as for recording with tungsten electrodes making it applicable for a wide range of insects. A micro thermistor air velocity sensor is placed within 2 mm from the preparation to record the momentary air flow. The signal conditioning electronic circuits are battery powered, and the signals can be stored on a portable tape recorder. Field recordings were made from individual male antennal pheromone receptors ofAegeria myopaeformis andAdoxophyes orana. In all recordings the instantaneous firing frequency of the receptor cells was strongly modulated by the air velocity. Analysis of the data may provide information about the average pheromone concentration and the fine structure of pheromone plumes under various conditions.     

cbb3-Type Cytochrome c Oxidases,Aerobic Respiratory Enzymes,Impact the Anaerobic Life of Pseudomonas aeruginosa PAO1

For bacteria, many studies have focused on the role of respiratory enzymes in energy conservation; however, their effect on cell behavior is poorly understood. Pseudomonas aeruginosa can perform both aerobic respiration and denitrification. Previous studies demonstrated that cbb₃-type cytochrome c oxidases that support aerobic respiration are more highly expressed in P. aeruginosa under anoxic conditions than are other aerobic respiratory enzymes. However, little is known about their role under such conditions. In this study, it was shown that cbb₃ oxidases of P. aeruginosa PAO1 alter anaerobic growth, the denitrification process, and cell morphology under anoxic conditions. Furthermore, biofilm formation was promoted by the cbb₃ oxidases under anoxic conditions. cbb₃ oxidases led to the accumulation of nitric oxide (NO), which is produced during denitrification. Cell elongation induced by NO accumulation was reported to be required for robust biofilm formation of P. aeruginosa PAO1 under anoxic conditions. Our data show that cbb₃ oxidases promote cell elongation by inducing NO accumulation during the denitrification process, which further leads to robust biofilms. Our findings show that cbb₃ oxidases, which have been well studied as aerobic respiratory enzymes, are also involved in denitrification and influence the lifestyle of P. aeruginosa PAO1 under anoxic conditions.     

Portable wireless neurofeedback system of EEG alpha rhythm enhances memory

Background

Effect of neurofeedback training (NFT) on enhancement of cognitive function or amelioration of clinical symptoms is inconclusive. The trainability of brain rhythm using a neurofeedback system is uncertainty because various experimental designs are used in previous studies. The current study aimed to develop a portable wireless NFT system for alpha rhythm and to validate effect of the NFT system on memory with a sham-controlled group.

Methods

The proposed system contained an EEG signal analysis device and a smartphone with wireless Bluetooth low-energy technology. Instantaneous 1-s EEG power and contiguous 5-min EEG power throughout the training were developed as feedback information. The training performance and its progression were kept to boost usability of our device. Participants were blinded and randomly assigned into either the control group receiving random 4-Hz power or Alpha group receiving 8–12-Hz power. Working memory and episodic memory were assessed by the backward digital span task and word-pair task, respectively.

Results

The portable neurofeedback system had advantages of a tiny size and long-term recording and demonstrated trainability of alpha rhythm in terms of significant increase of power and duration of 8–12 Hz. Moreover, accuracies of the backward digital span task and word-pair task showed significant enhancement in the Alpha group after training compared to the control group.

Conclusions

Our tiny portable device demonstrated success trainability of alpha rhythm and enhanced two kinds of memories. The present study suggest that the portable neurofeedback system provides an alternative intervention for memory enhancement.

     

A New Method To Monitor Airborne Inoculum of the Fungal Plant Pathogens Mycosphaerella brassicicola and Botrytis cinerea

We describe a new microtiter immunospore trapping device (MTIST device) that uses a suction system to directly trap air particulates by impaction in microtiter wells. This device can be used for rapid detection and immunoquantification of ascospores of Mycosphaerella brassicicola and conidia of Botrytis cinerea by an enzyme-linked immunosorbent assay (ELISA) under controlled environmental conditions. For ascospores of M. brassicicola correlation coefficients (r²) of 0.943 and 0.9514 were observed for the number of MTIST device-impacted ascospores per microtiter well and the absorbance values determined by ELISA, respectively. These values were not affected when a mixed fungal spore population was used. There was a relationship between the number of MTIST device-trapped ascospores of M. brassicicola per liter of air sampled and the amount of disease expressed on exposed plants of Brassica oleracea (Brussels sprouts). Similarly, when the MTIST device was used to trap conidia of B. cinerea, a correlation coefficient of 0.8797 was obtained for the absorbance values generated by the ELISA and the observed number of conidia per microtiter well. The relative collection efficiency of the MTIST device in controlled plant growth chambers with limited airflow was 1.7 times greater than the relative collection efficiency of a Burkard 7-day volumetric spore trap for collection of M. brassicicola ascospores. The MTIST device can be used to rapidly differentiate, determine, and accurately quantify target organisms in a microflora. The MTIST device is a portable, robust, inexpensive system that can be used to perform multiple tests in a single sampling period, and it should be useful for monitoring airborne particulates and microorganisms in a range of environments.     

Testing limits to airflow perturbation device (APD) measurements

Background  

The Airflow Perturbation Device (APD) is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated.     

“Oxygen regulation” of the respiratory chain composition in the yeast Debaryomyces hansenii under multiple stress

It was shown that two stress factors, hypoxia and hyperosmotic shock, if applied simultaneously to the yeast Debaryomyces hansenii, display an antagonistic mode of interaction, which results in an increased degree of halophily of this microorganism under microaerobic conditions. Studies of the effects of respiration inhibitors (sodium azide and salicyl hydroxamic acid, SHA) and of the pattern of changes in the composition of the respiratory chain of Debaryomyces hansenii under the stated stress conditions led to the suggestion of three (or four) chains of electron transfer functioning simultaneously in the cell: the classical respiratory chain involving cytochrome-c oxidase, an alternative respiratory chain involving a cyanide-and azide-resistant oxidase, and additional respiratory chains involving oxidases resistant to salt, azide and SHA. Thus, the antagonistic mode of interaction between hypoxia and hyperosmotic shock results from the redirection of the electron flow from the salt-susceptible respiratory systems to the salt-unsusceptible ones encoded by “the hypoxia genes” and activated (induced) under microaerobic conditions.     

Respiratory Chain of Plant Mitochondria: XVIII. Point of Interaction of the Alternate Oxidase with the Respiratory Chain

Oxidation of the respiratory chain carriers of anaerobic, CO-saturated skunk cabbage (Symplocarpus foetidus) mitochondria, by means of an O₂ pulse, proceeds primarily through the cyanide-insensitive alternate oxidase, since the oxidation of cytochromes a and a₃ takes place with a half-time of 3 seconds, corresponding to the rate of dissociation of CO from reduced cytochrome a₃. Ubiquinone and part of the flavoprotein are oxidized within 1 second under these conditions, and this rapid rate of oxidation is strongly inhibited by m-chlorobenzhydroxamic acid (mCLAM), a specific inhibitor of the alternate oxidase of plant mitochondria. The rate of ubiquinone oxidation under these conditions in white potato (Solanum tuberosum) mitochondria, which have no alternate oxidase, is the same as that in skunk cabbage mitochondria treated with mCLAM. Ubiquinone, thus identified as the carrier common to both the cytochrome and alternate oxidase pathways, is linked to the alternate oxidase by a flavoprotein of midpoint potential 50 millivolts more negative with which it is in equilibrium. This arrangement provides a switch for diverting electron transport primarily through the cytochrome pathway under state 3 conditions and primarily through the alternate oxidase pathway under state 4 conditions.     

Land Surface Reflectance Retrieval from Hyperspectral Data Collected by an Unmanned Aerial Vehicle over the Baotou Test Site

To evaluate the in-flight performance of a new hyperspectral sensor onboard an unmanned aerial vehicle (UAV-HYPER), a comprehensive field campaign was conducted over the Baotou test site in China on 3 September 2011. Several portable reference reflectance targets were deployed across the test site. The radiometric performance of the UAV-HYPER sensor was assessed in terms of signal-to-noise ratio (SNR) and the calibration accuracy. The SNR of the different bands of the UAV-HYPER sensor was estimated to be between approximately 5 and 120 over the homogeneous targets, and the linear response of the apparent reflectance ranged from approximately 0.05 to 0.45. The uniform and non-uniform Lambertian land surface reflectance was retrieved and validated using in situ measurements, with root mean square error (RMSE) of approximately 0.01–0.07 and relative RMSE of approximately 5%–12%. There were small discrepancies between the retrieved uniform and non-uniform Lambertian land surface reflectance over the homogeneous targets and under low aerosol optical depth (AOD) conditions (AOD = 0.18). However, these discrepancies must be taken into account when adjacent pixels had large land surface reflectance contrast and under high AOD conditions (e.g. AOD = 1.0).     

Investigation of the electrostatic charge of basidiospores of the Phellinus igniarius group

The polarity and magnitude of primary electric charges carried by basidiospores in the airborne state were investigated in living fungal fruiting bodies under natural forest conditions using a portable experimental device designed by the author. The operating principle was the falling of spores in the homogeneous horizontal electric field. The vertical and horizontal components of the trajectories of the spores were determined according to their deposition sites on electrodes (vertical metal plates). Altogether 33 samples of spores were examined for polarity, 10 of these samples (with 10⁴–10⁶ spores per sample) also were used to calculate the mean spore charge-to-mass quotient and the mean spore charge. The detection limits of spore charge-to-mass quotient varied in the range from (4.9±2.3)×10^?5 to (1.36±0.33)×10^?4 C kg^?1. Basidiospores (subglobose, smooth, diameter of 4–6 μm) of the closely related (sibling) species Phellinus alni, P. nigricans, P. populicola and P. tremulae (Hymenochaetales, Basidiomycota) carried positive electrical charges that have mean values from 48 to 305 elementary charges. The intraspecies variation of the spore charge could depend on the natural variation in spore size.     

Evaluation and application potential of an accelerometer-based collar device for measuring grazing behavior of dairy cows

The commercially available collar device MooMonitor+ was evaluated with regards to accuracy and application potential for measuring grazing behavior. These automated measurements are crucial as cows feed intake behavior at pasture is an important parameter of animal performance, health and welfare as well as being an indicator of feed availability. Compared to laborious and time-consuming visual observation, the continuous and automated measurement of grazing behavior may support and improve the grazing management of dairy cows on pasture. Therefore, there were two experiments as well as a literature analysis conducted to evaluate the MooMonitor+ under grazing conditions. The first experiment compared the automated measurement of the sensor against visual observation. In a second experiment, the MooMonitor+ was compared to a noseband sensor (RumiWatch), which also allows continuous measurement of grazing behavior. The first experiment on n = 12 cows revealed that the automated sensor MooMonitor+ and visual observation were highly correlated as indicated by the Spearman’s rank correlation coefficient (r_s) = 0.94 and concordance correlation coefficient (CCC) = 0.97 for grazing time. An r_s-value of 0.97 and CCC = 0.98 was observed for rumination time. In a second experiment with n = 12 cows over 24-h periods, a high correlation between the MooMonitor+ and the RumiWatch was observed for grazing time as indicated by an r_s-value of 0.91 and a CCC-value of 0.97. Similarly, a high correlation was observed for rumination time with an r_s-value of 0.96 and a CCC-value of 0.99. While a higher level of agreement between the MooMonitor+ and both visual observation and RumiWatch was observed for rumination time compared to grazing time, the overall results showed a high level of accuracy of the collar device in measuring grazing and rumination times. Therefore, the collar device can be applied to monitor cow behavior at pasture on farms. With regards to the application potential of the collar device, it may not only be used on commercial farms but can also be applied to research questions when a data resolution of 15 min is sufficient. Thus, at farm level, the farmer can get an accurate and continuous measurement of grazing behavior of each individual cow and may then use those data for decision-making to optimize the animal management.     

A Multimodal,SU-8 - Platinum - Polyimide Microelectrode Array for Chronic In Vivo Neurophysiology

Utilization of polymers as insulator and bulk materials of microelectrode arrays (MEAs) makes the realization of flexible, biocompatible sensors possible, which are suitable for various neurophysiological experiments such as in vivo detection of local field potential changes on the surface of the neocortex or unit activities within the brain tissue. In this paper the microfabrication of a novel, all-flexible, polymer-based MEA is presented. The device consists of a three dimensional sensor configuration with an implantable depth electrode array and brain surface electrodes, allowing the recording of electrocorticographic (ECoG) signals with laminar ones, simultaneously. In vivo recordings were performed in anesthetized rat brain to test the functionality of the device under both acute and chronic conditions. The ECoG electrodes recorded slow-wave thalamocortical oscillations, while the implanted component provided high quality depth recordings. The implants remained viable for detecting action potentials of individual neurons for at least 15 weeks.     

Lon-Mediated Proteolysis of the FeoC Protein Prevents Salmonella enterica from Accumulating the Fe(II) Transporter FeoB under High-Oxygen Conditions

The Salmonella Feo system consists of the FeoA, FeoB, and FeoC proteins and mediates ferrous iron [Fe(II)] import. FeoB is an inner membrane protein that, along with contributions from two small hydrophilic proteins, FeoA and FeoC, transports Fe(II). We previously reported that FeoC binds to and protects the FeoB transporter from FtsH-mediated proteolysis. In the present study, we report proteolytic regulation of FeoC that occurs in an oxygen-dependent fashion. While relatively stable under low-oxygen conditions, FeoC was rapidly degraded by the Lon protease under high-oxygen conditions. The putative Fe-S cluster of FeoC seemed to function as an oxygen sensor to control FeoC stability, as evidenced by the finding that mutation of the putative Fe-S cluster-binding site greatly increased FeoC stability under high-oxygen conditions. Salmonella ectopically expressing the feoB and feoC genes was able to accumulate FeoB and FeoC only under low-oxygen conditions, suggesting that FeoC proteolysis prevents Salmonella from accumulating the FeoB transporter under high-oxygen conditions. Finally, we propose that Lon-mediated FeoC proteolysis followed by FtsH-mediated FeoB proteolysis helps Salmonella to avoid uncontrolled Fe(II) uptake during the radical environmental changes encountered when shifting from low-iron anaerobic conditions to high-iron aerobic conditions.     

Characterization of the biochemical properties of Campylobacter jejuni RNase III

Campylobacter jejuni is a foodborne bacterial pathogen, which is now considered as a leading cause of human bacterial gastroenteritis. The information regarding ribonucleases in C. jejuni is very scarce but there are hints that they can be instrumental in virulence mechanisms. Namely, PNPase (polynucleotide phosphorylase) was shown to allow survival of C. jejuni in refrigerated conditions, to facilitate bacterial swimming, cell adhesion, colonization and invasion. In several microorganisms PNPase synthesis is auto-controlled in an RNase III (ribonuclease III)-dependent mechanism. Thereby, we have cloned, overexpressed, purified and characterized Cj-RNase III (C. jejuni RNase III). We have demonstrated that Cj-RNase III is able to complement an Escherichia coli rnc-deficient strain in 30S rRNA processing and PNPase regulation. Cj-RNase III was shown to be active in an unexpectedly large range of conditions, and Mn²⁺ seems to be its preferred co-factor, contrarily to what was described for other RNase III orthologues. The results lead us to speculate that Cj-RNase III may have an important role under a Mn²⁺-rich environment. Mutational analysis strengthened the function of some residues in the catalytic mechanism of action of RNase III, which was shown to be conserved.     

An analysis of the control of phosphorylation-coupled respiration in isolated plant mitochondria

The control of phosphorylation-coupled respiration in isolated turnip (Brassica rapa) mitochondria was investigated according to the principles of metabolic control analysis as developed by H. Kacser and J. A. Burns ([1973] Symp Soc Exp Biol 32: 65-104) and R. Heinrich and T. A. Rapoport ([1974] Eur J Biochem 42: 97-105). Inhibitor titration studies were used to determine quantitatively the amount of control exerted by four individual processes—cytochrome bc₁, cytochrome oxidase, H⁺-ATPase, and the adenine nucleotide carrier—on respiratory flux under ADP-excess (state 3) and ADP-limited (state 4) conditions with a range of respiratory substrates. Under state 3 conditions control strength was found to be distributed between cytochrome oxidase, cytochrome bc₁, and H⁺-ATPase in decreasing order of importance. The adenine nucleotide carrier exerted no control on respiratory flux under these conditions. Control strength at each step was found to vary with different substrates and with the respiratory flux as altered by ADP supply, i.e. virtually zero control strength at cytochrome oxidase and cytochrome bc₁ under state 4 conditions.     

Effects of hypoxia and body size on the oxygen consumption of the bivalve Arctica islandica (L.)

The relationship between oxygen consumption and body weight has been examined in Arctica islandica (L.).Large Arctica exhibit a high degree of respiratory independence under hypoxic conditions; like other species studied, respiratory independence increases markedly with increasing body size. Respiratory independence can also be modified by temperature and physiological condition and it is concluded that the division of species per se into oxygen regulators and oxygen conformers is not merited. These terms describe only the extremes of what is a variable capacity to maintain respiratory independence during hypoxia.     

Evidence for a Chemiosmotic Model of Dehalorespiration in Desulfomonile tiedjei DCB-1

Desulfomonile tiedjei DCB-1, a sulfate-reducing bacterium, conserves energy for growth from reductive dehalogenation of 3-chlorobenzoate by an uncharacterized chemiosmotic process. Respiratory electron transport components were examined in D. tiedjei cells grown under conditions for reductive dehalogenation, pyruvate fermentation, and sulfate reduction. Reductive dehalogenation was inhibited by the respiratory quinone inhibitor 2-heptyl-4-hydroxyquinoline N-oxide, suggesting that a respiratory quinoid is a component of the electron transport chain coupled to reductive dehalogenation. Moreover, reductive dehalogenation activity was dependent on 1,4-naphthoquinone, a possible precursor for a respiratory quinoid. However, no ubiquinone or menaquinone could be extracted from D. tiedjei. Rather, a UV-absorbing quinoid which is different from common respiratory quinones in chemical structure according to mass spectrometric and UV absorption spectroscopic analyses was extracted. ATP sulfurylase, adenosine phosphosulfate reductase, and desulfoviridin sulfite reductase, enzymes involved in sulfate reduction, were constitutively expressed in the cytoplasm of D. tiedjei cells grown under all three metabolic conditions. A periplasmic hydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. A membrane-bound, periplasm-oriented formate dehydrogenase was detected only in cells grown with formate as electron donor, while a cytoplasmic formate dehydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. Results from dehalogenation assays with D. tiedjei whole-cell suspensions and cell extracts suggest that the membrane-bound reductive dehalogenase is cytoplasm oriented. The data clearly demonstrate an enzyme topology in D. tiedjei which produces protons directly in the periplasm, generating a proton motive force by a scalar mechanism.     

A Lab Assembled Microcontroller-Based Sensor Module for Continuous Oxygen Measurement in Portable Hypoxia Chambers

Background

Hypoxia-based cell culture experiments are routine and essential components of in vitro cancer research. Most laboratories use low-cost portable modular chambers to achieve hypoxic conditions for cell cultures, where the sealed chambers are purged with a gas mixture of preset O₂ concentration. Studies are conducted under the assumption that hypoxia remains unaltered throughout the 48 to 72 hour duration of such experiments. Since these chambers lack any sensor or detection system to monitor gas-phase O₂, the cell-based data tend to be non-uniform due to the ad hoc nature of the experimental setup.

Methodology

With the availability of low-cost open-source microcontroller-based electronic project kits, it is now possible for researchers to program these with easy-to-use software, link them to sensors, and place them in basic scientific apparatus to monitor and record experimental parameters. We report here the design and construction of a small-footprint kit for continuous measurement and recording of O₂ concentration in modular hypoxia chambers. The low-cost assembly (US$135) consists of an Arduino-based microcontroller, data-logging freeware, and a factory pre-calibrated miniature O₂ sensor. A small, intuitive software program was written by the authors to control the data input and output. The basic nature of the kit will enable any student in biology with minimal experience in hobby-electronics to assemble the system and edit the program parameters to suit individual experimental conditions.

Results/Conclusions

We show the kit’s utility and stability of data output via a series of hypoxia experiments. The studies also demonstrated the critical need to monitor and adjust gas-phase O₂ concentration during hypoxia-based experiments to prevent experimental errors or failure due to partial loss of hypoxia. Thus, incorporating the sensor-microcontroller module to a portable hypoxia chamber provides a researcher a capability that was previously available only to labs with access to sophisticated (and expensive) cell culture incubators.