Long-term Hg pollution-induced structural shifts of bacterial community in the terrestrial isopod (Porcellio scaber) gut.

In previous studies we detected lower species richness and lower Hg sensitivity of the bacteria present in egested guts of Porcellio scaber (Crustacea, Isopoda) from chronically Hg polluted than from unpolluted environment. Basis for such results were further investigated by sequencing of 16S rRNA genes of mercury-resistant (Hgr) isolates and clone libraries. We observed up to 385 times higher numbers of Hgr bacteria in guts of animals from polluted than from unpolluted environment.

Real-time visualization of oxidative stress in a floating macrophyte Lemna minor L. exposed to cadmium, copper, menadione, and AAPH.

An ultra-sensitive digital imaging system was employed to visualize oxidative stress in intact L. minor plants exposed to Cd, Cu, menadione, AAPH, and ascorbate in real time. The increase of ROS production was assessed by measuring the rate of fluorescence intensity increases of the test medium supplemented with a fluorescing probe (dichlorofluorescein diacetate).

Growth, delayed fluorescence and pigment composition of four Prorocentrum minimum strains growing at two salinities.

Prorocentrum minimum is a potentially harmful and widely distributed marine dinoflagellate. Several P. minimum strains have already been studied, showing phylogenetical relations of strains isolated from the same geographical regions.

Delayed fluorescence as a measure of nutrient limitation in Dunaliella tertiolecta.

The applicability of the delayed fluorescence (DF) for the purpose of distinguishing the cells growing in different nutrient conditions was researched on the marine unicellular algae Dunaliella tertiolecta Butcher (Chlorophyta). The DF intensity (DFI), as a measure of living algal biomass, was compared with other biomass measures--the cell concentration, chlorophyll a and fluorescence. The photosynthetic activity index (PhAI), a non-dimensional physiological index of photosynthesis calculated from a combination of DFI and F(0) was introduced.

Imaging of intracellular spherical lamellar structures and tissue gross morphology by a focused ion beam/scanning electron microscope (FIB/SEM).

We report the use of a focused ion beam/scanning electron microscope (FIB/SEM) for simultaneous investigation of digestive gland epithelium gross morphology and ultrastructure of multilamellar intracellular structures. Digestive glands of a terrestrial isopod (Porcellio scaber, Isopoda, Crustacea) were examined by FIB/SEM and by transmission electron microscopy (TEM). The results obtained by FIB/SEM and by TEM are comparable and complementary.

Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure.

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500microM. High accumulation of cadmium was observed (12,320+/-2155microgg(-1) at 500microM CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence.

Antioxidative responses of duckweed (Lemna minor L.) to short-term copper exposure.

Goal, Scope And Background: Elevated concentrations of copper in the environment result in accumulation of the metal in plants and cause an increase in reactive oxidative species (ROS). The first response to elevated amounts of ROS is increased levels of enzymatic and non-enzymatic antioxidants that reduce oxidative stress. The aim of our study was to evaluate the early stages of antioxidative responses to the low copper concentrations usually present in moderately polluted environments.

Read-out of soft X-ray contact microscopy microradiographs by focused ion beam/scanning electron microscope.

A novel focused ion beam-based technique is presented for the read-out of microradiographs of Caenorhabditis elegans nematodes generated by soft x-ray contact microscopy (SXCM). In previous studies, the read-out was performed by atomic force microscopy (AFM), but in our work SXCM microradiographs were imaged by scanning ion microscopy (SIM) in a focused ion beam/scanning electron microscope (FIB/SEM). It allows an ad libitum selection of a sample region for gross morphologic to nanometric investigations, with a sequence of imaging and cutting.

Focused ion beam/scanning electron microscopy studies of Porcellio scaber (Isopoda, Crustacea) digestive gland epithelium cells.

The focused ion beam (FIB) was used to prepare cross sections of precisely selected regions of the digestive gland epithelium of a terrestrial isopod P. scaber (Isopoda, Crustacea) for scanning electron microscopy (SEM). The FIB/SEM system allows ad libitum selection of a region for gross morphologic to ultrastructural investigation, as the repetition of FIB/SEM operations is unrestricted.

Focused ion beam for microscopy and in situ sample preparation: application on a crustacean digestive system.

We prove that the focused ion beam (FIB) machine can be used as a microscope and as an in situ cutting device for tissue and cells. For the first time we obtain high-resolution ion images, complemented by electron imaging of different animal tissues both from uncoated and coated samples. In our study, we select the digestive system of Porcellio scaber (isopoda, crustacea) as a test system for FIB microscopy and in situ sample preparation.

Screening for antibacterial activity in 72 species of wood-colonizing fungi by the Vibrio fisheri bioluminescence method.

Resistance of pathogenic bacteria to antibiotics leads scientists to discover new antibacterial drugs. Ninety samples of wood-colonizing fungi were cultivated on agar plates, and their extracts tested for antibacterial activity using the Vibrio fischeri bioluminescence test. Two fungi species, Serpula lacrymans and Nectria vilior, were found to be a potential new source of thermostable antibiotics.

Alternating electric fields stimulate ATP synthesis in Escherichia coli.

External alternating electric fields of low intensity stimulated membrane bound ATP synthesis in starving Escherichia coli cells with electric field amplitudes of 2.5-50 V/cm and a frequency optimum at 100 Hz. The model of electrocon-formational coupling was used to analyze the frequency and amplitude responses of ATP synthesis.