External Membranes Research Articles

Investigation of lactate productivity in membrane bioreactors on C5/C6 carbohydrates

The aim of this work was to investigate the productivity of continuous lactate fermentations at increased cell densities on simulated lignocellulosic hydrolyzate and wheat straw hydrolyzates using Ca(OH)2 suspensions as base. To this end, a semi-automated membrane bioreactor prototype with external tubular membranes was designed and constructed. Long-term continuous fermentations were run in membrane bioreactor mode and compared to batch and continuous mode. Fouling of the membranes proved to be the major bottleneck in the process. The semi-automated membrane module switch elegantly circumvented this problem, allowing constant operating conditions throughout extended periods of time. Maximal productivities of 30.5gkg−1.h−1 could be reached in the prototype during 30.5h combined with an average lactate concentration of 85.4gkg−1 and complete consumption of C5 and C6 carbohydrates. In this fermentation zone, the (liquid) residence time was 2.8h. These numbers demonstrate significant performance improvements in comparison with batch and (regular) continuous conditions.

Plant signaling pathways activating defence response and interfering mechanisms by pathogen effectors, protein decoys and bodyguards

Plants activate an immune response in defense against microbial pathogens. The first layer of immunity consists in the recognition of microbial fingerprints, called Pathogen Associated Molecular Pattern (PAMP), by a set of Pattern Recognition Receptors (PRR). In addition, the degradation products from fungi, bacteria and plant cells are recognised as Damage Associated Molecular Pattern (DAMP). The first layer of plant defence is based on Pattern Recognition Receptors (PRR) on the membrane. These receptors, either receptor kinases or receptor-like proteins (RLPs), associating with cytoplasmic kinases, recognize the presence of PAMPs, thus activating a local response named PAMP-triggered immunity (PTI), that is not strong but effective towards many pathogen species. Here we discuss and focus on Elongation Factor Tu Receptors (EFR) and flagellin sensing (FLS) receptors. In leucine-rich repeat (LRR) receptor proteins, the hydrophobic LLR domains are exposed on external membranes, providing the protein-protein interaction modules. Plants evolved this protein-protein interaction domain several times during the development of mechanisms to defend themselves from viruses, virulence factors, enzymes and effectors of bacterial and fungal pathogens. Pathogens in addition evolved proteins and enzymes that are injected in the plant cell to counterfight plant immune signaling pathways. These effectors are recognised by plant receptors sensing their presence of their cognate avirulence genes. These receptors originated from recombination during evolution and only occur in some specific tomato genotypes, instead of the widely occurring PPRs. Effector Triggered Immunity (ETI) allows a plant response to effector proteins that is more strong, but is race specific. It leads to local necrosis and apoptosis, and to the establishment of the hypersensitive response (HR). For biotrophic or hemibiotrophic pathogens, necrosis is an effective way to limit their spread, while for necrotrophic pathogens this is not efficient and sufficient way to limit their spread, since depends on the timing of infection and on the plant development phase. Pathogenic fungi strategy relies on the formation of specialised structures, or haustoria, that facilitate the nutrient uptake form plant cells. In this review, we summarize the most recent knowledge on plant pathogens and the mechanisms they evolved to circumvent plant defences among which pathogen effectors, protein decoys inactivating plant defence signals. Effectors are recognised through their binding to plant proteins by means of plant receptors, that activate the Effector Triggered Immunity (ETI). In particular, we focus on the Solanaceae, discussing general mechanisms and specific pathways that confer resistance to various pathogens. There is an arm race between plants and fungal and bacterial pathogens that has led to new protein variants and protein decoys (pseudokinases, inhibitors and sponges blocking glucanases, and Transcription Activator Like Effectors). Advances in understanding the function of pathogen effectors will provide new ways to improve plant immunity and mechanisms of defence against their pests. Finally, we present possible combinations of interventions, from gene engineering to chemical priming, acting on signaling pathways regulated by jasmonate and salicylate hormones, to increase plant resistance and activate plant defences without affecting crop yields.

One-Step Detection of Major Lipid Components in Submicroliter Volumes of Unpurified Liposome and Cell Suspensions.

Liposomes and cells have high lipid contents, which are the main components of the external and internal membranes. Mass spectrometry (MS) is widely used in the analysis of the lipids present in the biological matrixes. However, MS analysis of liposome and cell suspensions is challenging due to the presence of other high-abundance matrix components (e.g., salts, buffers, and growth media) that cause ion suppression. These interfering species would normally be removed by dialysis or centrifugation. Here we propose a simple and fast method to detect major lipid components in cells and cell suspensions by MS while circumventing dialysis and centrifugation. Capillary hydrodynamic chromatography (HDC) has been coupled online with the aid of an electrospray ionization (ESI) interface to an ion-trap mass spectrometer. Complex samples containing bioparticles and a large amount of potential interferences (buffer, inorganic salts, amino acids) were separated hydrodynamically, detected optically (by light absorption/scattering), and immediately transferred to the MS interface. Liposomes and animal cells are disintegrated during electrospray, and the constituent lipids are ionized. The signal-to-noise ratios are ∼10× higher in HDC-ESI-MS than in direct infusion ESI-MS experiments (with or without dilution). This method has been tested on liposomes (containing phosphatidylcholine and phosphatidylglycerol) and four types of animal/human cells, i.e., mouse macrophages (RAW 264.7), human breast cancer cells (T47D and Hs578T), and mouse preadipocyte cells (3T3-L1). We suggest that HDC-ESI-MS can be used in quality control analyses of bioparticle suspensions in the fields of biotechnology, molecular biology, drug discovery, and cosmetics.

Low energy anaerobic membrane bioreactor for municipal wastewater treatment

Achieving low effluent BOD5 concentrations and stable performance while treating municipal wastewater at ambient temperature has been difficult for anaerobic biotechnology without using membranes. Membrane operation has typically required energy inputs greater than traditionally needed for activated sludge aeration, thus defeating one main objective of utilizing anaerobic biotechnology. However, new low-energy membrane operational strategies are being evaluated to make anaerobic membrane bioreactors (AnMBR) more energy efficient. In this study, four 3.3 L bench-scale AnMBRs using external crossflow tubular membranes were fed synthetic and real municipal wastewater at 10 and 25°C and evaluated on the basis of energy demand and organic removal. The membranes were operated at atypically low crossflow velocities of 0.018–0.3m/s, and with or without fluidized GAC, to reduce AnMBR energy demand. Use of GAC in membranes allowed for significant reduction in crossflow velocity without reducing membrane run-time between cleanings and resulted in energy demands of 0.05–0.13kWh/m3. The AnMBRs were able to produce permeate BOD5≤10mg/L at bioreactor HRTs of 4.2–9.8h, even at 10°C. When factoring in theoretical energy production, the AnMBR described herein is estimated to require 70–100% less energy compared to activated sludge, indicating net neutral energy demand may be feasible for BOD5 and nutrient removal from municipal wastewater.

DNA-based biosensors with polyvinyl alcohol external membrane as a tool for the evaluation of antioxidant activity of white wines

Abstract Electrochemical DNA-based biosensors with external protective membranes were prepared for the evaluation of antioxidant properties of white wines against pro-oxidant hydroxyl radicals. A glassy carbon working electrode (GCE) was modified using a layer-by-layer deposition technique with low molecular weight double stranded DNA and an outer sphere polymer film membrane of Nafion, chitosan or polyvinylalcohol. The composition of a working procedure with membrane-covered DNA biosensors were optimized with respect to their voltammetric response in solution of the DNA redox indicator [Fe(CN)6]3-/4- after the incubation in white wines. Polyvinylalcohol (PVA) film was proved to be the suitable membrane. The PVA/DNA/GCE biosensor was used for the detection of a deep degradation of the surface-attached DNA at the incubation in the cleavage agent and for the evaluation of antioxidant properties of white wines at the incubation in mixtures of cleavage agent and wine. The investigation of the biosensors with protective membranes represents a significant contribution to utilization of the electrochemical DNA based biosensors for practical purposes.

Surface hydrophilicity modification of PVDF membranes with an external electric field in the phase inversion process

To increase the surface hydrophilicity of PVDF membranes, in this paper, an electric enhancing method was adopted to treat PVDF nascent membranes during the phase inversion process. It was found that when PEG 600 was taken as the additive, the surface water contact angle of the PVDF membrane treated under 2 kV electric field was decreased from 84.0o to 65.7o. The reason for the surface elements change of the PVDF membranes prepared under the electric field was analyzed in detail with the dielectric parameters of the polymer dope solutions. Results from BSA adsorption experiment showed that the antifouling ability of the external electric field-treated membranes was distinctly enhanced when compared with that of the untreated membranes. The amount of BSA adsorbed by the treated membranes was lower by 38-43%. Compared with the common chemical reaction methods to synthesize hydrophilic additives or membrane materials, the electric field-assisted processing method did not involve any additional chemical synthesis process and it was capable of realizing better hydrophilicity.

Incomplete punctal canalization -a balloon variant of the external membrane: a case report

IntroductionIncomplete punctal canalization is an uncommon congenital disorder characterized by a dysgenetic punctum with membranes. External membranes, the most common type of incomplete punctal canalization are flat and overlie the punctum as a veil. We describe a newer variant of incomplete punctal canalization, its clinical profile, diagnostic criteria and management.Case presentationA 9-year-old Indian boy presented with watering of his right eye since birth. His right eye lower punctal area showed an avascular translucent elevation that appeared to have a smooth dome shape. An examination at high magnification showed the slopes of the dome gradually merging and contiguous with the tarsal conjunctiva. Based on a very high degree of suspicion, an impression of atypical external membrane variety of incomplete punctal canalization was made. Membranotomy was successful in the management of his condition.ConclusionsA high degree of suspicion is the key point in the diagnosis of this variant, keeping in mind the other features described for incomplete punctal canalization- external membrane. It is possible that ballooning of these membranes may represent an evolutionary stage in the process of complete canalization and this could be the starting point for further dacryo-embryologic exploration and correlations.

Changes in Ultrastructure and Expression of Steroidogenic Factor-1 in Ovaries of Zebrafish Danio rerio Exposed to Glyphosate

Glyphosate is a broad-spectrum organophosphate (OP) herbicide, highly soluble in water, and when applied in terrestrial systems it penetrates into soil, eventually reaching the aquatic community and affecting nontarget organisms. The aim of this study was to evaluate the toxicity of glyphosate on ovaries of zebrafish (Danio rerio). Ovaries (n = 18 per triplicate) were exposed to 65 μg/L of glyphosate [N-(phosphonomethyl) glycine] for 15 d. This concentration was determined according to Resolution 357/2005/CONAMA/Brazil, which establishes the permissible concentration of glyphosate in Brazilian inland waters. Nonexposed ovaries (n = 18 per triplicate) were used as control. Subsequently, morphology and expression of steroidogenic factor-1 (SF-1) of exposed and nonexposed ovaries was determined. No apparent changes were noted in general morphology of exposed and nonexposed ovaries. However, a significant increase in diameter of oocytes was observed after exposure to glyphosate. When ovarian ultrastructure was examined the presence of concentric membranes, appearing as myelin-like structures, associated with the external membranes of mitochondria and with yolk granules was found. After glyphosate exposure, immunohistochemistry and immunoblotting revealed greater expression of SF-1 in the oocytes, which suggests a relationship between oocyte growth and SF-1 expression. These subtle adverse effects of glyphosate on oocytes raised a potential concern for fish reproduction. These results contribute to understanding glyphosate-induced toxicity to nontarget organisms, showing subcellular and molecular impairments that may affect reproduction in +female fish.

Activation of Small Conductance Calcium-Activated Potassium Channels by Sarcoplasmic Reticulum Calcium Release Attenuates Delayed Afterdepolarizations in Ventricular Myocytes

Small conductance calcium-activated potassium (SK) channels are upregulated in ventricular myocytes from human patients and animal models of heart failure (HF). However, their activation mechanism and function in ventricular myocytes remain elusive. We overexpressed SK2 channels in adult rat ventricular myocytes using adenovirus gene transfer to test the hypotheses that activation of SK channels in ventricular myocytes requires calcium release from sarcoplasmic reticulum (SR), and that upregulation of SK currents contributes to reducing triggered activity. Simultaneous voltage clamp and confocal calcium imaging experiments in SK2-overexpressing cells demonstrated that depolarizing voltage steps resulted in transient outward currents sensitive to the specific SK channel inhibitor apamin. SR calcium release induced by rapid application of 10 mM caffeine evoked repolarizing SK currents, whereas complete exhaustion of SR calcium stores eliminated SK currents in response to depolarizing voltage steps, despite intact calcium influx through L-type calcium channels. Furthermore, apamin-sensitive SK currents were activated by pro-arrhythmic global spontaneous SR calcium release events (calcium waves, SCWs). Current-clamp experiments demonstrated that SK overexpression reduced the amplitude of delayed afterdepolarizations (DADs) resulting from SCWs and shortened action potential duration (APD). Immuno-localization studies revealed that overexpressed SK channels were distributed both at external sarcolemmal membranes and along the Z-lines, resembling the distribution of endogenous SK channels. In summary, SR calcium release is both necessary and sufficient for the activation of SK channels in rat ventricular myocytes. SK currents contribute to repolarization during action potentials and attenuate DADs driven by SCWs. Thus, SK upregulation in HF may have an anti-arrhythmic effect by shortening APD and reducing triggered activity.

Sarcoplasmic reticulum Ca²⁺ release is both necessary and sufficient for SK channel activation in ventricular myocytes.

SK channels are upregulated in human patients and animal models of heart failure (HF). However, their activation mechanism and function in ventricular myocytes remain poorly understood. We aim to test the hypotheses that activation of SK channels in ventricular myocytes requires Ca(2+) release from sarcoplasmic reticulum (SR) and that SK currents contribute to reducing triggered activity. SK2 channels were overexpressed in adult rat ventricular myocytes using adenovirus gene transfer. Simultaneous patch clamp and confocal Ca(2+) imaging experiments in SK2-overexpressing cells demonstrated that depolarizations resulted in Ca(2+)-dependent outward currents sensitive to SK inhibitor apamin. SR Ca(2+) release induced by rapid application of 10 mM caffeine evoked repolarizing SK currents, whereas complete depletion of SR Ca(2+) content eliminated SK currents in response to depolarizations, despite intact Ca(2+) influx through L-type Ca(2+) channels. Furthermore, voltage-clamp experiments showed that SK channels can be activated by global spontaneous SR Ca(2+) release events Ca(2+) waves (SCWs). Current-clamp experiments revealed that SK overexpression reduces the amplitude of delayed afterdepolarizations (DADs) resulting from SCWs and shortens action potential duration. Immunolocalization studies showed that overexpressed SK channels are distributed both at external sarcolemmal membranes and along the Z-lines, resembling the distribution of endogenous SK channels. In summary, SR Ca(2+) release is both necessary and sufficient for the activation of SK channels in rat ventricular myocytes. SK currents contribute to repolarization during action potentials and attenuate DADs driven by SCWs. Thus SK upregulation in HF may have an anti-arrhythmic effect by reducing triggered activity.

Superresolution Imaging—Caveolae, Caveolins, Mitochondria, and Function in Heart

Our ability to investigate questions improves as methods advance. Such advances may permit some issues to be resolved while other questions develop a new complexion and engender new and/or refined questions. Here experiments that combine superresolution optical imaging (or stochastic optical reconstruction microscopy, STORM (1,2)) and electron microscopy (EM) tomography are presented in a study on cardiac structures by Wong et al. (3). The focus is primarily on the spatial organization of the cardiac transverse tubular (TT) system, also called the transverse-axial tubular system (TATS). While the transverse character of the TT/TATS system clearly dominates in healthy mammalian adult ventricular myocytes, heart failure leads to disorganization and dedifferentiation of this tubular system (4). In addition, the organization of caveolin-3 and the ryanodine receptors (RyR2 or the Ca2+ release channel in the junctional sarcoplasmic reticulum) are presented and discussed. The work seeks to link dynamic cellular structures and nanoscopic organization to cellular function. This work is also a very nice demonstration of the value of combining superresolution optical microscopy (STORM, PALM, and STED—see below (1,2,5–7)) and EM tomography (8,9). The name of the protein caveolin comes from the name of structures with which they are reported to be associated: the caveolae (10). The caveolae are omega-shaped invaginations of the surface membrane (10,11) of cells with localized function and organization (12). In cardiac and skeletal muscle cells, the caveolae are thought to be associated with both the external sarcolemmal membrane and the membranes of the TATS. In some cases, caveolae are associated with mitochondria (13) and in adipocytes with lipid metabolism (14). It is thus often thought that the spatial organization of the caveolae as well as the specific array of proteins and lipids in the very small omega-shaped structure underlie caveolar function. There is, however, a distinction of the concept between caveolin-rich membranes and caveolae as presented in the work by Wong et al. (3). The authors show that the majority of the surface membrane (external SL and TATS membranes) containing caveolin-3 does not include caveolar invaginations. Although there are TT dilations in the region of the junctional sarcoplasmic reticulum, they are not caveolae. This suggests that some quantitative reexamination of a number of hypotheses may be in order. Perhaps the exciting recent findings by Makarewich et al. (15), for example, would be recast if caveolae were not present. Nevertheless, the findings of Wong et al. (3) serve mainly to draw attention to a critical question: What exactly do the caveolins do? In addition, the work demonstrates both the power and utility of superresolution optical imaging combined with EM tomography.

The Senescence Process of Internal Thoracic Artery

OBJECTIVE. The Internal Thoracic Artery (ITA) is the most widely used arterial conduit for coronary artery by-pass, because it is very rarely affected by atherosclerosis. However, the state of its wall at the time of grafting procedure could influence the long-term outcome of coronary artery by-pass. METHODS. We have investigated 20 specimens of distal human ITA, derived from 14 male patients and 6 female patients, aged between 68 and 77 years, operated for atherosclerotic coronary artery disease. The specimens, collected after surgical skeletonization during coronary artery by-pass procedures, were fixed in 10% neutral buffered formalin and then paraffin embedded. Besides to haematoxylin-eosin, histochemistry for elastic fibers (Weigert‘s staining, Van Gieson‘s staining, Verhoeff‘s staining) and immunohistochemistry for muscle cells (smooth muscle actin, caldesmon, desmin) and CD34 have been performed, applying the standard avidin-biotin complex (ABC) method. RESULTS. A degenerative pathology, most likely due to aging, characterized by the fragmentation of the internal and external elastic membranes and by the consumption of the elastic network of the tunica media has been microscopically observed in a quarter of our patients, without the achievement of classical signs of overt atherosclerosis (cholesterol deposition, lipidic infiltration, endothelial ulceration, intimal calcification), which could compromise the long-term patency of the graft. CONCLUSIONS. The degenerative change is followed by a remodelling process, based on the proliferation of unspecialized muscle like cells, able to preserve the architecture and the stability of the arterial wall and consequently its functional long-term behaviour.

Incomplete punctal canalisation: the external and internal punctal membranes. Outcomes of membranotomy and adjunctive procedures

AimsTo study the clinical and diagnostic profile of punctal dysgenesis with membranes, to classify and correlate the membranes clinicopathologically and study the outcomes of membranotomy.MethodsA prospective interventional study involving 55...

Comparative performance evaluation of microfiltration submerged and pressurized membrane treatment of wastewater

Continuous microfiltration (CMF) submerged or pressurized membranes, has been widely used recently as a treatment process for the removal of particles and pathogens from water and wastewater. The CMF technology has great potential for wide ranging applications including treatment of surface seawater, municipal and industrial wastewater treatment, groundwater and drinking water. The technical feasibility of this process has been demonstrated through a number of pilot and bench scale research studies in the Kuwait Institute for Scientific Research, Kuwait. Full scale systems are operational in various parts of the world. The CMF process is already considered as a viable alternative for many waste treatments. The emergence of submerged membranes that utilize fairly economical polymer-based membranes and require less energy than external membranes has revolutionized municipal wastewater treatment and has tremendous potential in larger scale, high volume throughput facilities across the globe. This paper discusses the technical and analytical performance of two types of microfiltration system, one with submerged membranes and the other with pressurized membranes. The paper covers performance data and discusses the technical parameters of water productivity and filtrate quality. It also covers the evaluation of membrane performance, system availability and techno-economic study for both systems.

THE INFLUENCE OF THE CHONDROITINE SULPHATE ON THE SERTOLI AND LEYDIG CELLS ULTRASTRUCTURE

The peculiarities of the Sertoli and Leydig cells ultrastructure testis of rats under influenceof the chondroitine sulphate after destructive influence of the serotonin hydrochloride have beenstudied. It determined that chondroitine sulphate furthers to retrieve of the typical architectonics ofthe testis of rats Sertoli and Leydig cells have been undergone of destructive impact of serotoninhydrochloride. Chondroitine sulphate furthers to normalization of submicroscopic mitochondrialorganization manifesting by absence of the lysis areas of the external membranes and crysts andby appearance of the dividing forms. The adequate cells bioenergy consumption is renewing. TheSertoli and Leydig cells bioenergy correction under the influence of chondroitine sulphate lead toactivation of the synthetic processes and to the reparation of intracellular structure.

Cu(GlyGlyHis) effects on MCF7 cells: Copper uptake, reactive oxygen species generation and membrane topography changes

Elevated levels of copper have been detected in various types of human cancer cells, such as breast cancer cells, and a number of mechanisms have been proposed to explain the action and influence of copper on tumor progress. In this work, we found that stimulating the proliferation of mammary epithelial MCF7 cells with the high-redox-potential copper complex Cu (GlyGlyHis) is associated with the copper-induced intracellular generation of reactive oxygen species (ROS) that induces lipid peroxidation and causes increased roughness of external cell membranes, which leads to the formation of larger cell domes. The results presented herein provide new insights into the molecular link between copper and the proliferation of breast cancer cells and, consequently, into the mechanism by which changes in redox balance and ROS accumulation regulates cell membrane roughness.

Investigation of the sludge thickening potential of waste activated sludge using membranes

Abstract Sludge thickening with membranes, especially external membranes, is recently emerging. In this study the feasibility of external membranes for thickening of waste activated sludge up to 30 g l−1 was studied using a test cell. In batch-wise thickening experiments, the characteristics of the filtration process under various operating conditions (w = 0.8–2 m s−1, TMP = 1–1.8 bar) and with different membranes (four UF membranes, one MF membrane) were investigated. For the different membranes no considerable difference in the sludge thickening behaviour was observed, despite huge variations in membrane pore size and water permeability. By increasing the cross-flow velocity, significant improvements in permeability could be achieved, whereas an increase in TMP at constant cross-flow velocity slightly deteriorated the permeability during the sludge thickening. The obtained permeabilities of 15–20 l m−2 h−1 bar−1 at MLSS concentrations higher than 30 g l−1 are economical and, therefore this process is an...

Морфолого-цитологІчнІ змінИ клітиН дріжджіВ зА низькиХ темпеРатуР

Yeast Saccharomyces is widely used in food industry, in particular at fermentation products production. The preservation of yeast taxonomical and technological characteristics is important and may be carried out by different methods, among which cryopreservation is the most prospective. Thus, the target of the research was to study the morphological and cytological changes of yeast cells at low temperatures applying light and electron microscopes according to the standard procedure. The results show that freezing at -17 oС and -50oС results in partial modification of the cell’s form, damage of the cell membrane, outlet of cell material, modification of karyosomes and external membranes of yeast ascospores. Some cells remain undamaged and do not undergo essential changes. Yeast spores are more resistant to the cryopreservation in comparison with vegetative cells. The results obtained may be used in food industry and biotechnology when choosing the optimal modes of cryopreservation of industrial cultures of yeast.

青岛沿岸水体原生生物群落与水质状况的关系

Protistan communities are characterized by high ecological and species diversity due to their short life cycles and by a quick response to environmental changes. Many species respond rapidly to pollutants and often inhabit environments that are unfavorable to most of metazoans and some can even tolerate extremes of environmental conditions to macrofauna. As predominant components of protistan communities, ciliates and flagellates may react more quickly to environmental changes than any other eukaryotic organisms because of their rapid growth and delicate external membranes and can thus serve as bioindicators of water pollution. Polyurethane foam unit (PFU) is an artificial substrate able to host planktonic, periphytic and benthic protistan assemblages. The PFU method has been widely and successfully employed to evaluate freshwater quality all over the world. However, as far as we know, this method has not been used in marine habitats as effective as in freshwater biotopes because of the influence of tidal current and circulation in near-shore area. In order to evaluate the feasibility of using the PFU method to assess coastal water quality, Xu et al. modified the conventional PFU method and presented a bottled PFU (BPFU) system and successfully used to evaluate the water quality in Korean coastal waters. Our study is the first to use the BPFU method for bioassessment in Chinese offshore areas. Three stations in the coastal waters off Qingdao, China were selected as study area from September to October in 2007. Margalef diversity index was calculated by d = (S-1) / lnN. The relationship between the protistan community parameters and marine water quality was analyzed. MacArthur and Wilson equilibrium model: St =Seq(1-e-Gt ) was applied to assess the colonizing process of protistan communities. A total of 263 species of protists were identified during the survey. Among these were 83 diatoms, 59 flagellates, 31 sarcodines, and 90 ciliates. In terms of species composition, site 1 was dominated mainly by bacterivores (e. g. , Euplotes parabalteatus, Uronema marinum and Pleuronema coronatum ), site 3 mainly by algivores ( e. g. , Strombidinopsis minima, Strombidium apolatum and Hartmannula augustipilosa), and site 2 was in an intermediate status. These results are consistent with the environmental conditions: site 3 had the best water quality, site 1 was the most eutrophic site, and site 2 was the moderate one. Furthermore, the colonization processes and functional parameters (i. e. Seq, G and T90% ) of communities correlated with the pollution status and could thus clearly discriminate the different classes of water quality as measured by physicochemical indicators. But the Margalef diversity index did not coincide with the water conditions: site 1 had the highest index value (on average 4. 16), while site 2 had the lowest (on average 3． 00). Nonetheless, this work further suggests the practicability of the BPFU method for biomonitoring of coastal water pollution. Our study also indicates that protistan communities are more effective and accurate than protozoan communities in reflecting water quality.

Experimental Modeling and Discussion of Syncytial Connections in the Nervous System

To solve the problem of the possibility of syncytial connection in the nervous system, this paper for the first time presents the evidence of experimental syncytial fusion of neurons. Neurons, isolated from the ganglia of the mollusc Lymnaea stagnalis and freed from the surrounding glia by pronase treatment, were drawn together by centrifugation and were kept in the culture medium for two days in the aggregated state. The neurons preserved the ability to generate normal processes. At the borders of adjacent cells, contacting mutual protrusions (feet) were formed that were separated from each other by vacuole-like enlargements of the intercellular clefts. Using the electron microscope, it was shown that at the borders of contacting feet the external cell membranes were destroyed. Only residual fragments of the destroyed membranes were detected. The cytoplasm of one adjacent cell was continuous with the cytoplasm of the other. Thus, the experiments confirm once more the correctness of the cell theory concerning the common main properties of all the cells and expand the concepts of the neuronal theory by the statement that in the nervous system, along with chemical synapses and electrical membrane contacts, the syncytial interneuronal connections are also possible.