Analysis of interaction of bacterial cells and bacteriophages in conducting suspensions with an acoustic sensor

The possibility of analyzing bacterial cells infected by a specific bacteriophage, using Escherichia coli as an example, with an acoustic sensor directly in suspensions with different initial electrical conductivities was studied. The analysis was based on measurement of the time dependence of phase and the complete loss of output sensor signals of fixed frequency before and after biological interaction of microbial cells and bacteriophages. The aforementioned sensor makes it possible to detect bacterial cells and assess their viability in conducting suspensions. It was shown that the conductivity of the buffer solution should not exceed 10 μS/cm and the minimum detectable concentration of microbial cells was ~10⁴ cells/mL.     

Specific Features of Digestive Function Development in Larvae of Some Salmonid Fish

We studied the activities of digestive enzymes responsible for the digestion of food carbohydrate and protein components in plant-eating fish at various stages of larval development. The activities of all digestive enzymes tend to rise during larval development. Species specific features of the alimentary canal functioning have been described.     

Immunochemical and single molecule force spectroscopy studies of specific interaction between the laminin binding protein and the West Nile virus surface glycoprotein E domain II

ELISA and Western blot immunochemical data attest an effective and highly specific interaction of the surface glycoprotein E domain II (DII) of the tick born encephalitis and Dengue viruses with the laminin binding protein (LBP). Based on a highly conservative structure of the DII in different flaviviruses we propose a similarly effective interaction between the LBP and the DII of the surface glycoprotein E of the West Nile virus. We report the results of studies of this interaction by immunochemical and single molecule force spectroscopy methods. The specific binding between these species is confirmed by both methods.     

Interstitial Ciliates: Benthic Microaerophiles or Planktonic Anaerobes?

We observed marine benthic interstitial ciliates Geleia sp. and Tracheloraphis sp. inhabiting the water column of a chemically stratified salt pond. This habitat is uncharacteristic for interstitial ciliates, yet they displayed active and abundant planktonic populations (up to 800 and 250 cells/liter, respectively) and a well-defined pattern of vertical distribution. Completely absent from the oxygenated epilimnion, they first appeared at the oxic/anoxic interface and were present throughout the anoxic hypolimnion. The data could not be explained by a passive removal (e.g. by currents) of these ciliates from their conventional habitat (soft sediments) to water column. The results suggest that 1) these ciliates favored an anoxic environment, and 2) they switched to a planktonic lifestyle as appropriate conditions (seasonal anoxia) developed in the water column. This sharply contrasts the classic view of these ciliates as specifically benthic and aerobic (albeit microaerophilic) organisms. We hypothesize that Geleia sp. and Tracheloraphis sp. can readily grow in either water column or benthos, but are typically found in sediments simply because they contain their preferred (anoxic) niche.     

Spatial propagation of interictal discharges along the cortex

Interictal discharges (IIDs) accompany epileptic seizures and highlight the mechanisms of pathological activity. The propagation of IIDs along the neural tissue is not well understood. To simulate IID propagation, this study proposes a new mathematical model that uses the conductance-based refractory density approach for glutamatergic and GABAergic neuronal populations. The mathematical model is found to be consistent with experimental double-patch registrations in the 4-aminopyridine in vitro model of epilepsy. In slices, the spontaneous activity of interneurons leads to their synchronization by means of the depolarizing GABAmediated response, thus initiating IIDs. Modeling reveals a clustering of interneuronal synchronization followed by IIDs with activity fronts that propagate along the cortex. The GABA-mediated depolarization either remains to be subthreshold for the principal neurons and thus results in pure GABAergic IIDs (IID1s) or leads to glutamatergic excitation, thus resulting in another type of IIDs (IID2s). In both the model and experiment, IIDs propagate as waves, with constant activity profiles and velocity. The speed of IIDs is of the order of tens of mm/s and is larger for IID2s than for IID1s (40 and 20?mm/s, respectively). The simulations, consistent with experimental observations, show that the wavelike propagation of IIDs initiated by interneurons is determined by local synaptic connectivity under the conditions of depolarizing GABA.     

A Study of the Effect of Terahertz Electromagnetic Radiation on Microbial Cell Viability

Biophysics - Abstract—The effect of pulsed terahertz radiation at a wavelength of 66 μm, a pulse duration of 100 ns, and a pulse energy of 200 mJ on a suspension of microbial cells was...     

Desiccation and zinc binding induce transition of tomato abscisic acid stress ripening 1, a water stress- and salt stress-regulated plant-specific protein, from unfolded to folded state

Abscisic acid stress ripening 1 (ASR1) is a low molecular weight plant-specific protein encoded by an abiotic stress-regulated gene. Overexpression of ASR1 in transgenic plants increases their salt tolerance. The ASR1 protein possesses a zinc-dependent DNA-binding activity. The DNA-binding site was mapped to the central part of the polypeptide using truncated forms of the protein. Two additional zinc-binding sites were shown to be localized at the amino terminus of the polypeptide. ASR1 protein is presumed to be an intrinsically unstructured protein using a number of prediction algorithms. The degree of order of ASR1 was determined experimentally using nontagged recombinant protein expressed in Escherichia coli and purified to homogeneity. Purified ASR1 was shown to be unfolded using dynamic light scattering, gel filtration, microcalorimetry, circular dichroism, and Fourier transform infrared spectrometry. The protein was shown to be monomeric by analytical ultracentrifugation. Addition of zinc ions resulted in a global change in ASR1 structure from monomer to homodimer. Upon binding of zinc ions, the protein becomes ordered as shown by Fourier transform infrared spectrometry and microcalorimetry, concomitant with dimerization. Tomato (Solanum lycopersicum) leaf soluble ASR1 is unstructured in the absence of added zinc and gains structure upon binding of the metal ion. The effect of zinc binding on ASR1 folding and dimerization is discussed.     

Incubation of environmental samples in a diffusion chamber increases the diversity of recovered isolates

The majority of microorganisms from natural environments cannot be grown in the laboratory. The diffusion-chamber-based approach is an alternative method that allows microorganisms to grow in their natural environment. An inoculum is sandwiched between semipermeable (0.03-mum-pore-size) membranes of the chamber, which is then returned to the source environment. The chamber allows for a free exchange of chemicals with the external milieu by diffusion while restricting the movement of cells. We used freshwater pond sediment to inoculate diffusion chambers and petri dishes. The diffusion chambers were incubated on top of the sediment for 4 weeks. Both chamber and petri dish cultivation resulted in the isolation of numerous representatives of Alpha-, Beta-, and Gammaproteobacteria; Actinobacteria; Firmicutes; and Bacteroidetes. However, the diffusion-chamber-based approach also led to the isolation of species from rarely cultivated groups, such as Deltaproteobacteria, Verrucomicrobia, Spirochaetes, and Acidobacteria. Material from the chambers was also transferred to new chambers in order to learn whether this will increase the recovery of isolates. Several isolates could be obtained only from material transferred through multiple diffusion chambers. This suggests that continuous cultivation in diffusion chambers adapts some microorganisms for growth under otherwise prohibitive in vitro conditions.