Low Level of Cystic Fibrosis Transmembrane Conductance Regulator Is Associated with Human Sperm Autophagy and Vitality

Low sperm motility is one of the main causes of male infertility. Cystic fibrosis transmembrane conductance regulator (CFTR, an anion channel protein) is related to the progressive motility of sperm. CFTR disruptor CFTRinh-172 or forskolin (FSK) in this study were used to treat human sperm separately, and the rates of sperm autophagy and progressive motility, mitochondrial membrane potential (MMP) and ATP concentration, and the expression levels of related factors were detected to explore their relationship. It was showed that sperms treated with CFTRinh-172 or FSK reduced the levels of cAMP, CFTR and PKA, but increased sperm autophagy rate, expression levels of AMPK and LC3B. However, reactive oxygen species content had no significant difference. It was indicated that low level of CFTR performed with cAMP and its downstream effectors such as PKA and AMPK to regulate mitochondrial structure and function, leading to increased autophagy rate and reduced vitality of sperm.

Variations in chlorophyll content, stomatal conductance, and photosynthesis in Setaria EMS mutants

Chlorophyll (Chl) content,especially Chl b content,and stomatal conductance (G_s) are the key factors affecting the net photosynthetic rate (P_n).Setaria italica,a diploid C_4 panicoid species with a simple genome and high transformation efficiency,has been widely accepted as a model in photosynthesis and drought-tolerance research.The current study characterized Chl content,G_s,and P_n of 48 Setaria mutants induced by ethyl methanesulfonate.A total of 24,34,and 35 mutants had significant variations in Chl content,G_s,and P_n,respectively.Correlation analysis showed a positive correlation between increased G_s and increased P_n,and a weak correlation between decreased Chl b content and decreased P_n was also found.Remarkably,two mutants behaved with significantly decreased Chl b content but increased P_n compared to Yugu 1.Seven mutants behaved with significantly decreased G_s but did not decrease P_(n )compared to Yugu 1.The current study thus identified various genetic lines,further exploration of which would be beneficial to elucidate the relationship between Chl content,G_s,and P_n and the mechanism underlying why C_4 species are efficient at photosynthesis and water saving.

Hall conductance of a non-Hermitian two-band system with k-dependent decay rates

Two-band model works well for Hall effect in topological insulators. It turns out to be non-Hermitian when the system is subjected to environments, and its topology characterized by Chern numbers has received extensive studies in the past decades. However, how a non-Hermitian system responses to an electric field and what is the connection of the response to the Chern number defined via the non-Hermitian Hamiltonian remains barely explored. In this paper, focusing on a k-dependent decay rate, we address this issue by studying the response of such a non-Hermitian Chern insulator to an external electric field. To this aim, we first derive an effective non-Hermitian Hamiltonian to describe the system and give a specific form of k-dependent decay rate. Then we calculate the response of the non-Hermitian system to a constant electric field.We observe that the environment leads the Hall conductance to be a weighted integration of curvature of the ground band and hence the conductance is no longer quantized in general. And the environment induces a delay in the response of the system to the electric field. A discussion on the validity of the non-Hermitian model compared with the master equation description is also presented.

Responses of leaf stomatal and mesophyll conductance to abiotic stress factors

Plant photosynthesis assimilates CO_(2)from the atmosphere,and CO_(2)diffusion efficiency is mainly constrained by stomatal and mesophyll resistance.The stomatal and mesophyll conductance of plants are sensitive to abiotic stress factors,which affect the CO_(2)concentrations at carboxylation sites to control photosynthetic rates.Early studies conducted relevant reviews on the responses of stomatal conductance to the environment and the limitations of mesophyll conductance by internal structure and biochemical factors.However,reviews on the abiotic stress factors that systematically regulate plant CO_(2)diffusion are rare.Therefore,in this review,the rapid and long-term responses of stomatal and mesophyll conductance to abiotic stress factors(such as light intensity,drought,CO_(2)concentration and temperature)and their physiological mechanisms are summarized.Finally,future research trends are also investigated.

Fractal Prediction Model of Thermal Contact Conductance of Rough Surfaces

The thermal contact conductance problem is an important issue in studying the heat transfer of engineering surfaces, which has been widely studied since last few decades, and for predicting which many theoretical models have been established. However, the models which have been existed are lack of objectivity due to that they are mostly studied based on the statistical methodology characterization for rough surfaces and simple partition for the deformation formats of contact asperity. In this paper, a fractal prediction model is developed for the thermal contact conductance between two rough surfaces based on the rough surface being described by three-dimensional Weierstrass and Mandelbrot fractal function and assuming that there are three kinds of asperity deformation modes： elastic, elastoplastic and fully plastic. Influences of contact load and contact area as well as fractal parameters and material properties on the thermal contact conductance are investigated by using the presented model. The investigation results show that the thermal contact conductance increases with the increasing of the contact load and contact area. The larger the fractal dimension, or the smaller the fractal roughness, the larger the thermal contact conductance is. The thermal contact conductance increases with decreasing the ratio of Young＇s elastic modulus to the microhardness. The results obtained indicate that the proposed model can effectively predict the thermal contact conductance at the interface, which provide certain reference to the further study on the issue of heat transfer between contact surfaces.

Predicted interfacial thermal conductance and thermal conductivity of diamond/Al composites with various interfacial coatings

The interfacial thermal conductance （ITC） and thermal conductivity （TC） of diamond/Al composites with various coatings were theoretically studied and discussed. A series of predictions and numerical analyses were performed to investigate the effect of thickness, sound velocity, and other parameters of coating layers on the ITC and TC. It is found that both the ITC and TC decline with increasing coating thickness, especially for the coatings with relatively low thermal conductivity. Nevertheless, if the coating thickness is close to zero, or quite a small value, the ITC and TC are mainly determined by the constants of the coating material. Under this condition, coatings such as Ni, TiC, Mo 2 C, SiC, and Si can significantly improve the ITC and TC of diamond/Al composites. By contrast, coatings like Ag will exert the negative effect. Taking the optimization of interfacial bonding into account, conductive carbides such as TiC or Mo 2 C with low thickness can be the most suitable coatings for diamond/Al composites.

Response of stomatal conductance of two tree species to vapor pressure deficit in three climate zones

Stomatal behavior is a central topic of plant ecophysiological research under global environmental change. However, the physiological mechanism controlling the response of stomata to vapor pressure deficit （VPD） or relative humidity （RH） has been inadequately understood till now. In this study, responses of stomatal conduc- tance （gs） to VPD in two species of trees （Fraxinus chinensis Roxb., Populus alba L. var. pyramidalis Bge.）in three different climate zones （Jinan with typical warm humid/semi-humid climate, Urumqi with temperate continental arid climate and Turpan with extreme arid desert climate） were measured. Levels of two phytohormones （abscisic acid, ABA; indole-3-acetic acid, IAA） in the leaves of the two tree species at these three sites were also measured by high performance liquid chromatography. The results showed that the responses of gs to an increasing VPD in these two tree species at the three sites had peak curves which could be fitted with a Log Normal Model （gs=a.exp（-O.5（In（DIc）lb）2）. The VPD/RH values corresponding to the maximum g, can be calculated using the fitting models for the two tree species in the three sites. We found that the calculated g, -VPD correlated nega- tively with relative air humidity in the three sites during the plant growth period （April to October 2010）, which showed the values of g,-max-VPD were related to the climate conditions. The prevailing empirical stomatal model （Leuning model） and optimal stomatal behavior model could not properly simulate our measured data. The water use efficiency in the two tree species did not show obvious differences under three very different climatic conditions, but the highest gs, photosynthetic and transpiration rates occurred in P. alba var. of Turpan. The sensitivity in re- sponse of g~ to VPD in leaves of the two trees showed positive correlations with the concentration of ABA, which implied that ABA level could be used as an indicator of the sensitivity of stomatal response to VPD. Our results confirmed that the prediction of the response of gs to VPD might be incomplete in the two current popular models. Therefore, an improved g, model which is able to integrate the results is needed. Also, the stomatal response mechanism of single peak curves of g~ to VPD should be considered.

Inhibitory Effects of Blockage of Intermediate Conductance Ca^(2+) -Activated K^+ Channels on Proliferation of Hepatocellular Carcinoma Cells

The roles of intermediate conductance Ca2＋-activated K＋ channel （IKCal） in the pathogene- sis of hepatocellular carcinoma （HCC） were investigated. Immunohistochemistry and Western blotting were used to detect the expression of IKCal protein in 50 HCC and 20 para-carcinoma tissue samples. Real-time PCR was used to detect the transcription level of IKCal mRNA in 13 HCC and 11 para-carcinoma tissue samples. The MTT assay was used to measure the function of IKCal in human HCC cell line HepG2 in vitro. TRAM-34, a specific blocker of IKCal, was used to intervene with the function of IKCal. As compared with para-carcinoma tissue, an over-expression of IKCal protein was detected in HCC tissue samples （P〈0.05）. The mRNA expression level of IKCal in HCC tissues was 2.17 times higher than that in para-carcinoma tissues. The proliferation of HepG2 cells was suppressed by TRAM-34 （0.5, 1.0, 2.0 and 4.0 pxnol/L） in vitro （P〈0.05）. Our results suggested that IKCal may play a role in the proliferation of human HCC, and IKCal blockers may represent a potential therapeutic strategy for HCC.

Emerging role of cystic fibrosis transmembrane conductance regulator- an epithelial chloride channel in gastrointestinal cancers

Cystic fibrosis transmembrane conductance regulator(CFTR), a glycoprotein with 1480 amino acids, has been well established as a chloride channel mainly expressed in the epithelial cells of various tissues and organs such as lungs, sweat glands, gastrointestinal system, and reproductive organs. Although defective CFTR leads to cystic fibrosis, a common genetic disorder in the Caucasian population, there is accumulating evidence that suggests a novel role of CFTR in various cancers, especially in gastroenterological cancers, such as pancreatic cancer and colon cancer. In this review, we summarize the emerging findings that link CFTR with various cancers, with focus on the association between CFTR defects and gastrointestinal cancers as well as the underlying mechanisms. Further study of CFTR in cancer biology may help pave a new way for the diagnosis and treatment of gastrointestinal cancers.

Quantized Conductance of Majorana Zero Mode in the Vortex of the Topological Superconductor(Li_(0.84)Fe_(0.16))OHFeSe

The Major ana zero mode(MZM), which manifests as an exotic neutral excitation in superconductors, is the building block of topological quantum computing. It has recently been found in the vortices of several iron-based superconductors as a zero-bias conductance peak in tunneling spectroscopy. In particular, a clean and robust MZM has been observed in the cores of free vortices in(Li_(0.84)Fe_(0.16))OHFeSe. Here using scanning tunneling spectroscopy, we demonstrate that Major ana-induced resonant Andreev reflection occurs between the STM tip and this zero-bias bound state,and consequently, the conductance at zero bias is quantized as 2e^2/h. Our results present a hallmark signature of the MZM in the vortex of an intrinsic topological superconductor, together with its intriguing behavior.

Cystic fibrosis transmembrane conductance regulator chloride channel blockers:Pharmacological,biophysical and physiological relevance

Dysfunction of the cystic fibrosis transmembrane con-ductance regulator(CFTR) chloride channel causes cys-tic fibrosis, while inappropriate activity of this channeloccurs in secretory diarrhea and polycystic kidney dis-ease. Drugs that interact directly with CFTR are there-fore of interest in the treatment of a number of diseasestates. This review focuses on one class of small mol-ecules that interacts directly with CFTR, namely inhibi-tors that act by directly blocking chloride movementthrough the open channel pore. In theory such com-pounds could be of use in the treatment of diarrheaand polycystic kidney disease, however in practice allknown substances acting by this mechanism to inhibitCFTR function lack either the potency or specificity forin vivo use. Nevertheless, this theoretical pharmaco-logical usefulness set the scene for the developmentof more potent, specific CFTR inhibitors. Biophysically,open channel blockers have proven most useful as ex-perimental probes of the structure and function of theCFTR chloride channel pore. Most importantly, the useof these blockers has been fundamental in developing afunctional model of the pore that includes a wide innervestibule that uses positively charged amino acid sidechains to attract both permeant and blocking anionsfrom the cell cytoplasm. CFTR channels are also subjectto this kind of blocking action by endogenous anionspresent in the cell cytoplasm, and recently this blocking effect has been suggested to play a role in the physio-logical control of CFTR channel function, in particular as a novel mechanism linking CFTR function dynamically to the composition of epithelial cell secretions. It has also been suggested that future drugs could target this same pathway as a way of pharmacologically increasing CFTR activity in cystic fibrosis. Studying open channel blockers and their mechanisms of action has resulted in significant advances in our understanding of CFTR as a pharmacological target in disease states, of CFTR chan-nel structure and function, and of how CFTR activity is controlled by its local environment.

Cystic fibrosis transmembrane conductance regulator prevents ischemia/reperfusion induced intestinal apoptosis via inhibiting PI3K/AKT/NF-κB pathway

BACKGROUND Intestinal ischemia/reperfusion(I/R)injury is a fatal syndrome that occurs under many clinical scenarios.The apoptosis of intestinal cells caused by ischemia can cause cell damage and provoke systemic dysfunction during reperfusion.However,the mechanism of I/R-induced apoptosis remains unclear.Cystic fibrosis transmembrane conductance regulator(CFTR)is a cAMP-activated chloride channel.Few researchers have paid attention to its role in intestinal I/R injury,or the relationship between CFTR and intestinal apoptosis induced by hypoxia/reoxygenation(H/R).AIM To investigate the effects of CFTR on I/R-induced intestinal apoptosis and its underlying molecular mechanisms.METHODS An intestinal I/R injury model was established in mice with superior mesenteric artery occlusion, and Caco2 cells were subjected to H/R for the simulation of I/R in vivo.RESULTSThe results suggested that CFTR overexpression significantly increased the Caco2 cell viability anddecreased cell apoptosis induced by the H/R. Interestingly, we found that the translocation of p65,an NF-κB member, from the cytoplasm to the nucleus after H/R treatment can be reversed by theoverexpression of CFTR, the NF-κB P65 would return from the nucleus to the cytoplasm asdetermined by immunostaining. We also discovered that CFTR inhibited cell apoptosis in theH/R-treated cells, and this effect was significantly curbed by the NF-κB activator BA, AKTinhibitor GSK690693 and the PI3K inhibitor LY294002. Moreover, we demonstrated that CFTRoverexpression could reverse the decreased PI3K/AKT expression induced by the I/R treatment invivo or H/R treatment in vitro.CONCLUSIONThe results of the present study indicate that the overexpression of CFTR protects Caco2 cells fromH/R-induced apoptosis;furthermore, it also inhibits H/R-induced apoptosis through thePI3K/AKT/NF-κB signaling pathway in H/R-treated Caco2 cells and intestinal tissues.

Multi-objective Optimal Design of High Frequency Probe for Scanning Ion Conductance Microscopy

Scanning ion conductance microscopy（SICM） is an emerging non-destructive surface topography characterization apparatus with nanoscale resolution. However, the low regulating frequency of probe in most existing modulated current based SICM systems increases the system noise, and has difficulty in imaging sample surface with steep height changes. In order to enable SICM to have the capability of imaging surfaces with steep height changes, a novel probe that can be used in the modulated current based bopping mode is designed. The design relies on two piezoelectric ceramics with different travels to separate position adjustment and probe frequency regulation in the Z direction. To fiarther improve the resonant frequency of the probe, the material and the key dimensions for each component of the probe are optimized based on the multi-objective optimization method and the finite element analysis. The optimal design has a resonant frequency of above 10 kHz. To validate the rationality of the designed probe, microstructured grating samples are imaged using the homebuilt modulated current based SICM system. The experimental results indicate that the designed high frequency probe can effectively reduce the spike noise by 26% in the average number of spike noise. The proposed design provides a feasible solution for improving the imaging quality of the existing SICM systems which normally use ordinary probes with relatively low regulating frequency.

Large-conductance Ca^2＋-activated K^＋ channel involvement in suppression of cerebral ischemia/reperfusion injury after electroacupuncture at Shuigou(GV26) acupoint in rats

Excess activation and expression of large-conductance Ca^2＋-activated K^＋ channels（BKCa channels） may be an important mechanism for delayed neuronal death after cerebral ischemia/reperfusion injury. Electroacupuncture can regulate BKCa channels after cerebral ischemia/reperfusion injury, but the precise mechanism remains unclear. In this study, we established a rat model of cerebral ischemia/reperfusion injury. Model rats received electroacupuncture of 1 m A and 2 Hz at Shuigou（GV26） for 10 minutes, once every 12 hours for a total of six times in 72 hours. We found that in cerebral ischemia/reperfusion injury rats, ischemic changes in the cerebral cortex were mitigated after electroacupuncture. Moreover, BKCa channel protein and m RNA expression were reduced in the cerebral cortex and neurological function noticeably improved. These changes did not occur after electroacupuncture at a non-acupoint（5 mm lateral to the left side of Shuigou）. Thus, our findings indicate that electroacupuncture at Shuigou improves neurological function in rats following cerebral ischemia/reperfusion injury, and may be associated with down-regulation of BKCa channel protein and m RNA expression. Additionally, our results suggest that the Shuigou acupoint has functional specificity.

Modulation of leaf conductance by root to shoot signaling under water stress in Arabidopsis

Signal communication between root and shoot plays a crucial role in plant resistance to water stress. While many studies on root to shoot signals have been carried out in many plant species, no information is available for the model plant, Arabidopsis, whose adoption has great significance for further probing the molecular aspects of long distance stress signals. Here, we introduced the es- tablishment of techniques for investigations of root to shoot signals in Arabidopsis. Stomata! movements in relation to root signals were probed by using these techniques. The results show that Arabidopsis is a suitable plant species for partial roots drying （PRD） experiments. In the PRD system, while no significant differences were found in leaf water potential between well-watered and stressed plants, water stress led to a decrease in leaf conductance, which suggests a regulation of stomatal movements by root to shoot signals. While water stress caused a significant increase in the concentration of sap abscisic acid （ABA） of xylem, no increase in xylem sap pH was observed. Moreover, the increase in the ABA content of xylem coincided with the decrease in leaf conductance, which suggests a possible role of ABA in the regulation of stomatal movements. Infrared temperature images showed that leaf tem- peratures of PRD plant were higher compared with those of well-watered plants, which further indicates that stomatal movements can be modulated by root signals. The confirmation of root to shoot signaling in Arabidopsis has established a basis for further inves- tigation into the molecular mechanisms of the root to shoot signaling under water stress.

Observation of hopping transitions for delocalized electrons by temperature-dependent conductance in silicon junctionless nanowire transistors

We demonstrate transitions of hopping behaviors for delocalized electrons through the discrete dopant-induced quantum dots in n-doped silicon junctionless nanowire transistors by the temperature-dependent conductance characteristics.There are two obvious transition platforms within the critical temperature regimes for the experimental conductance data,which are extracted from the unified transfer characteristics for different temperatures at the gate voltage positions of the initial transconductance gm peak in Vg1 and valley in Vg2. The crossover temperatures of the electron hopping behaviors are analytically determined by the temperature-dependent conductance at the gate voltages Vg1 and Vg2. This finding provides essential evidence for the hopping electron behaviors under the influence of thermal activation and long-range Coulomb interaction.

Stem radial CO_2 conductance affects stem respiratory CO_2 fluxes in ash and birch trees

The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes together provides an estimate of actual stem respiration(R_S).We know that the relative proportion of CO_2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO_2 conductance(g_c).A high g_c would favor the E_A pathway and a low g_cwould favor the F_Tpathway.However,g_chas only been measured once in situ and only in a single tree species.We measured g_cusing two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with R_S,E_A,F_T and DS.Stem radial CO_2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,E_Aconstituted the entire flux of respired CO_2 ,and F_Twas negative,indicating that additional CO_2 ,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,F_T was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO_2 to E_A caused E_Ato be 9% higher than the actual R_Sover the diel measurement period.Birch trees,which had lower g_c,also had a more commonly seen pattern,with E_A accounting for about 80% of the CO_2 released from local cell respiration and F_T accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L^(-1),respectively.Our results indicate that stem CO_2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO_2 that remains in the xylem or diffuses into the atmosphere.

EFFECT OF RARE EARTH ON CONDUCTANCE OF ALUMINUM WIRE

Effects of Rare Earth(Hereafter RE)on the conductance of high-purity and industrial-purity aluminum wires have been studied.RE increases the resistivity of the high-purity aluminum.No evidence has been found that RE will decrease the resistivity of industrial-pure aluminum under various RE content including 0.3%Ce.The individual role of RE and its combined effects with Fe and Si have been discussed too.

AC Conductance Through a Vibrating Molecular Dot in Kondo Regime

In the present paper,by applying the Lang-Firsov canonical transformation and the so-called non-crossingapproximation technique,we investigate the joint effects of the electron-phonon interaction and an external alternatinggate voltage on the transport of a quantum dot system in the Kondo regime.We find that,while the satellite Kondoresonant peaks appear in both the averaged local density of states and the differential conductance,the main Kondopeak at the Fermi energy is greatly suppressed.These results confirm the previous ones derived by other methods,suchas the equation of motion solution.Furthermore,based on the picture of virtual transition between quasi-eigenstates inthe system,we also give a slightly different explanation on these phenomena.

Size effect of quantum conductance in carbon nanotube Y-Junctions

This paper studies the quantum conductance properties of three-terminated carbon nanotube Y-junctions, which are built by connecting three （5,5） single-walled carbon nanotubes. The results show that the quantum conductance at the Fermi energy oscillates periodically with the junction＇s size, and the number of oscillating periodic layers is 3 which is the same as that in the two terminated （10, 0）/m（5, 5）/（10, 0） junctions. Moreover, this Y-junction with different size exhibits an obviously different distribution of electron current in the two drain branches, called shunt valve effect of electronic current. Thus the degree of this effect can be controlled and modulated directly by constructing the three branches＇ sizes or the distribution of defect. The results show in detail that the difference between the two drain currents can be up to two times for some constructions with special sizes. In addition, the uniform distribution of defects in the Y-junction leads to lower quantum conductance than that of other defect configurations.