Social interactions and cortisol treatment increase the production of aggressive electrocommunication signals in male electric fish,Apteronotus leptorhynchus

Brown ghost knife fish, Apteronotus leptorhynchus, continually emit a weakly electric discharge that serves as a communication signal and is sensitive to sex steroids. Males modulate this signal during bouts of aggression by briefly (approximately 15 ms) increasing the discharge frequency in signals termed "chirps." The present study examined the effects of short-term (1-7 days) and long-term (6-35 days) male-male interaction on the continuous electric organ discharge (EOD), chirping behavior, and plasma levels of cortisol and two androgens, 11-ketotestosterone (11KT) and testosterone. Males housed in isolation or in pairs were tested for short-term and long-term changes in their EOD frequency and chirping rate to standardized sinusoidal electrical stimuli. Within 1 week, chirp rate was significantly higher in paired fish than in isolated fish, but EOD frequency was equivalent in these two groups of fish. Plasma cortisol levels were significantly higher in paired fish than in isolated fish, but there was no difference between groups in plasma 11KT levels. Among paired fish, cortisol levels correlated positively with chirp rate. To determine whether elevated cortisol can cause changes in chirping behavior, isolated fish were implanted with cortisol-filled or empty Silastic tubes and tested for short-term and long-term changes in electrocommunication signals and steroid levels. After 2 weeks, fish that received cortisol implants showed higher chirp rates than blank-implanted fish; there were no difference between groups in EOD frequency. Cortisol implants significantly elevated plasma cortisol levels compared to blank implants but had no effect on plasma 11KT levels. These results suggest that male-male interaction increases chirp rate by elevating levels of plasma cortisol, which, in turn, acts to modify neural activity though an 11KT-independent mechanism.     

Changes in physico-chemical properties of human large intestine tumour cells membrane

Tumour cells produce and excrete to blood many substances which are present in the cell itself in trace amounts only. Our work has been aimed at the determination of changes in electric charge and in phospholipid composition of large intestine normal mucosa and colorectal cancer cells.Surface charge density of tumour unaffected mucosa and of tissue sections from tumours, was measured by electrophoresis. The measurements were carried out at various pH of solution. Membrane isoelectric point was determined by measuring its electric charge in function of pH as well as total positive charge at low pH and total negative charge at high pH. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC. Four phospholipid classes were identified: PI, PS, PE and PC and their surface concentrations were determined.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.Tumour changes provoke an increase in surface charge density of large intestine membrane, whereas the content of individual phospholipids increased or decreased depending on a patient.     

The secretory response through electric stimulation of differentiated PC12 rat pheochromocytoma cells transfected with neuropeptide Y fused with enhanced green fluorescent protein

Exocytosis in pheochromocytoma cells was induced by electric stimulation. To chase the movement of vesicles by electric stimulation, dense-core secretory vesicles were visualized by expression of the fusion protein between neuropeptide Y and enhanced green fluorescent protein (EGFP) in these differentiated PC12 rat pheochromocytoma cells. When the cells were stimulated with constant voltage potential at –300 mV, the movement of dense-core secretory vesicles could be regulated.     

Photoactivation of Electrogenic Activity in Chloroplasts and Its Relation to Photoinduced Swelling of Thylakoids

In patch-clamp experiments on isolated chloroplasts of Peperomia metallica Lind. et Rodig. (Piperaceae), the replacement of 50 mM KCl in a medium with 50 mM NH₄Cl strongly influenced the parameters of photocurrent known to reflect the generation of electric potential in thylakoids. The addition of NH⁺ ₄to the medium modified the induction curves of the photocurrent as well as the currents induced by single-turnover flashes in preilluminated chloroplasts. Under the action of a prolonged light pulse (1 s), the steady-state current was much higher in the ammonium-containing medium than in the presence of K⁺. Preillumination of a dark-adapted chloroplast with a 1-s light pulse suppressed the current induced by a single-turnover flash (6 s) in the presence of K⁺ but caused an elevation (by 50–150%) of the flash-induced current and shortening of its relaxation time in the presence of NH⁺ ₄. The origin of different induction kinetics for the photocurrent in K⁺ and NH⁺ ₄ media is partly clear, because ammonium prevents generation of the pH gradient and, subsequently, eliminates the pH-dependent suppression of the electron transport rate. However, this does not explain the origin of NH⁺ ₄-dependent photostimulation of the current generated by single-turnover flashes. This phenomenon arises from the thylakoid swelling caused by the accumulation of NH⁺ ₄ in the lumen and from the respective changes in the network resistances. The network element most sensitive to thylakoid swelling is the lateral resistance of the lumen: it decreases upon enlargement of the cross-section area. Stimulation of the flash-induced current by preillumination in the presence of NH⁺ ₄ was accompanied by accelerated relaxation of the current, indicating that the phenomena observed are caused by the reduction of network resistance involved in the discharge of the membrane capacity. Thus, the light-induced structural changes in the thylakoid system have a marked effect on the currents measured with the patch-clamp technique.     

TESTING HYPOTHESES OF NEURAL EVOLUTION IN GYMNOTIFORM ELECTRIC FISHES USING PHYLOGENETIC CHARACTER DATA

In this paper, we propose a method to test alternative hypotheses of phenotypic evolution. The method compares patterns observed in phylogenetic character data with patterns expected by explicit models of evolutionary process. Observed patterns of character-state diversity are assessed from four properties of character-state change derived from a phylogenetic analysis: the sequence and correlation of transformations on a cladogram and the spatial and functional localization of these transformations to parts of an organism. Patterns expressed in terms of the localization of transformations are compared with the expectations of null models that the number of transformations is proportional to measures of size or complexity. Deviations from the values expected by the null models are then compared with qualitative expectations of the models. The method is applied to characters in the nervous system of gymnotiform electric fishes. Patterns in the diversity of 63 reconstructed character-state changes are compared with the expectations of 10 published models of neural evolution. A total of 63 expectations are reviewed, of which 33 (52%) are found to be consistent with the gymnotiform neural data. In general, the models reviewed are not successful at making global predictions, in part because they have been cast in excessively general terms. The data support the conclusion that evolution in the nervous system of gymnotiforms has involved a mosaic of processes, each operating differentially on functional and developmental systems and at different spatial and temporal scales. The results also indicate that more refined models are required, each making more explicit predictions.     

Sustainability Indicators at the Firm Level

After reviewing recent attempts to develop sustainability indicators, this article shows how the principles of productive efficiency can be used to elaborate such indicators at the firm level. The theory of productive efficiency is somewhat expanded to incorporate fundamental issues of sustainable development: environment, equity, and futurtty. Efficiency, in the expanded notion of productive efficiency, is viewed as a necessary condition for sustainability. Working with aggregate performance indicators, it is important not to lose track of the relevant basic information. Therefore, instead of elaborating one unique indicator; we propose to implement several kinds of indicators, each of which stresses one particular focus (e.g., environmental vs. social concems). The definition of sustainable development indicators is illustrated with reference to a small data set of U.S. fossil fuel-fired electric utilities. In a sustainabiltty perspective, two important aspects are stressed, namely, the use of nonmewable resources and the inclusion of employment as a variable to maximize rather than an input to minimize. The article ends with a discussion of the significance of, and limits to, the proposed indicators.     

经皮椎板间内镜与椎板小开窗术治疗腰椎间盘突出症临床疗效比较

目的：分析和比较椎板间内镜与椎板小开窗术治疗腰椎间盘突出症的临床疗效和安全性指标。方法：使用回顾性分析的方法 对2012-2014 年共计126 例在我科行椎板间内镜手术或椎板小开窗手术的腰椎间盘突出患者进行分析和比较。通过纳入和排除 标准的筛选,经皮椎板间内镜组纳入48例,椎板小开窗组纳入78 例。结合详实的术后随访,对两组患者在花费,住院时间等一般 性指标,疼痛指标,功能指标,并发症等数据进行分析和比较。结果：两组患者在术后均取得明显的治疗疗效,在疼痛、功能等指标 中都有明显的改善。但两组之间并无明显统计学差异(P>0.05)。而椎板间内镜组在住院时间,出血量,切口长度及并发症等方面明 显的优于小开窗组,具有统计学意义(P<0.05)。结论：经皮椎板间内镜手术作为一种脊柱微创手术,治疗效果确切,安全性好,能体 现微创的优势,可作为椎间孔镜技术在治疗椎间盘突出症的有益补充,在临床中进一步的开展和推广。     

Crosstalk of cardiomyocytes and fibroblasts in co-cultures

Electromechanical function of cardiac muscle depends critically on the crosstalk of myocytes with non-myocytes. Upon cardiac fibrosis, fibroblasts translocate into infarcted necrotic tissue and alter their communication capabilities. In the present in vitro study, we determined a multiple parameter space relevant for fibrotic cardiac tissue development comprising the following essential processes: (i) adhesion to substrates with varying elasticity, (ii) dynamics of contractile function, and (iii) electromechanical connectivity. By combining electric cell-substrate impedance sensing (ECIS) with conventional optical microscopy, we could measure the impact of fibroblast–cardiomyocyte ratio on the aforementioned parameters in a non-invasive fashion. Adhesion to electrodes was quantified via spreading rates derived from impedance changes, period analysis allowed us to measure contraction dynamics and modulations of the barrier resistance served as a measure of connectivity. In summary, we claim that: (i) a preferred window for substrate elasticity around 7 kPa for low fibroblast content exists, which is shifted to stiffer substrates with increasing fibroblast fractions. (ii) Beat frequency decreases nonlinearly with increasing fraction of fibroblasts, while (iii) the intercellular resistance increases with a maximal functional connectivity at 75% fibroblasts. For the first time, cardiac cell–cell junction density-dependent connectivity in co-cultures of cardiomyocytes and fibroblasts was quantified using ECIS.