The Dutch N-cascade in the European perspective

The Netherlands is "well known" for its nitrogen problems; it has one of the highest reactive nitrogen (Nr) emission densities in the world. It is a small country at the delta of several large European rivers. Ever since the industrial revolution, there has been a growing excess of nutrients and related emissions into the atmosphere (ammonia, nitrogen oxides and nitrous oxide) and into groundwater and surface water (nitrate), leading to a large range of cascading environmental impacts. Vehicular traffic, sewage and animal husbandry are the main sources of oxidized and reduced forms of Nr. This paper provides an overview of the origin and fate of nitrogen in the Netherlands, the various reported impacts of nitrogen, the Dutch and European policies to reduce nitrogen emissions and related impacts. In addition, ways are presented to go forward to potentially solve the problems in a European perspective. Solutions include the improvement of nitrogen efficiencies in different systems, technological options and education.     

Population structure of the Baikalian amphipod Gmelinoides fasciatus (Stebbing)

Using the data on 71 individual sequences of the gene for the mitochondrial cytochrome-c-oxidase subunit one, molecular and phylogenetic characterization of the Baikalian amphipod, Gmelinoides fasciatus (Crustacea, Amphipoda), was performed. Interspecific polymorphism was demonstrated. Four main amphipod populations, Southeastern, Southwestern, Northern, and Central, were distinguished. A low level of genetic diversity typical of Southwestern population was revealed. For its explanation, the bottleneck hypothesis was proposed.     

Phylogenetic relationships of typical antbirds (Thamnophilidae) and test of incongruence based on Bayes factors

Background  

The typical antbirds (Thamnophilidae) form a monophyletic and diverse family of suboscine passerines that inhabit neotropical forests. However, the phylogenetic relationships within this assemblage are poorly understood. Herein, we present a hypothesis of the generic relationships of this group based on Bayesian inference analyses of two nuclear introns and the mitochondrial cytochrome b gene. The level of phylogenetic congruence between the individual genes has been investigated utilizing Bayes factors. We also explore how changes in the substitution models affected the observed incongruence between partitions of our data set.     

Effects of p-nitrophenol and organophosphorous nitroaromatic insecticides on the respiratory activity of free and immobilized cells of strains S-11 and BA-11 of Pseudomonas putida

The possibility of using the respiratory activity (RA) of microbial cells (of strains S-11 and BA-11 of Pseudomonas putida) as an instrument for quantitative determination of organophosphorous nitroaromatic insecticides, metaphors and sumithion, and their hydrolysis product, p-nitrophenol (PNP), has been explored. The dependences of RA on the concentrations of the three compounds were linear within the range 0.5-2.5 microM. The cells of the strain BA-11 exhibited maximum selectivity in the determination of the compounds. The RA of microbial cells differing in the modes of immobilization (adsorption to carrier surfaces vs. incorporation into gels) have been compared. Prospects of development of the microbial cell-based sensor system for determining metaphors, sumithion, and PNP in aqueous media are discussed.     

Voltage-induced nonconductive pre-pores and metastable single pores in unmodified planar lipid bilayer

Electric fields promote pore formation in both biological and model membranes. We clamped unmodified planar bilayers at 150-550 mV to monitor transient single pores for a long period of time. We observed fast transitions between different conductance levels reflecting opening and closing of metastable lipid pores. Although mean lifetime of the pores was 3 +/- 0.8 ms (250 mV), some pores remained open for up to approximately 1 s. The mean amplitude of conductance fluctuations (approximately 500 pS) was independent of voltage and close for bilayers of different area (40,000 and 10 microm(2)), indicating the local nature of the conductive defects. The distribution of pore conductance was rather broad (dispersion of approximately 250 pS). Based on the conductance value and its dependence of the ion size, the radius of the average pore was estimated as approximately 1 nm. Short bursts of conductance spikes (opening and closing of pores) were often separated by periods of background conductance. Within the same burst the conductance between spikes was indistinguishable from the background. The mean time interval between spikes in the burst was much smaller than that between adjacent bursts. These data indicate that opening and closing of lipidic pores proceed through some electrically invisible (silent) pre-pores. Similar pre-pore defects and metastable conductive pores might be involved in remodeling of cell membranes in different biologically relevant processes.     

The oncogenic action of nonfibrous mineral dusts]

Nonfibrous mineral dusts antigorite, basalt, cement, zeolite-klinoptilolite and gamma-alumina were tested for carcinogenic activity in rat experiments. Intraperitoneal injections of zeolite-klinoptilolite and gamma-alumina led to development of peritoneal mesotheliomas, whereas antigorite and cement had no carcinogenic potential. There is no differences in physicochemical and chemical properties between carcinogenically active and inactive nonfibrous dusts. A new class of carcinogenic substances is defined including basalt, zeolite-klinoptilolite and quartz which belong to nonfibrous mineral dusts.     

Evolutionary relationships of endemic Draparnaldioides simplex C. Meyer et Skabitch. Green alga from Lake Baikal with non-Baikalian taxa of chaetophoraceae (Chlorophyta) family

The phylogenetic relationships between Baikalian endemic green alga Draparnaldioides simplex C. Meyer et Skabitch., 1976 and holarctic taxa of green algae have been studied using the 18S rDNA gene fragment and internal transcribed ITS1 and ITS2 spacers of nuclear DNA. The Baikalian genus Draparnaldioides was shown to be a separate taxon. The level of genetic difference between the studied species and non-Baikalian taxa of sister groups of green algae is insignificant, which indicates the young age of the genus Draparnaldioides and its recent radiation from the common ancestor with genera Draparnaldia and Chaetophora.     

Direct exchange of vitamin B12 is demonstrated by modelling the growth dynamics of algal–bacterial cocultures

The growth dynamics of populations of interacting species in the aquatic environment is of great importance, both for understanding natural ecosystems and in efforts to cultivate these organisms for industrial purposes. Here we consider a simple two-species system wherein the bacterium Mesorhizobium loti supplies vitamin B₁₂ (cobalamin) to the freshwater green alga Lobomonas rostrata, which requires this organic micronutrient for growth. In return, the bacterium receives photosynthate from the alga. Mathematical models are developed that describe minimally the interdependence between the two organisms, and that fit the experimental observations of the consortium. These models enable us to distinguish between different mechanisms of nutrient exchange between the organisms, and provide strong evidence that, rather than undergoing simple lysis and release of nutrients into the medium, M. loti regulates the levels of cobalamin it produces, resulting in a true mutualism with L. rostrata. Over half of all microalgae are dependent on an exogenous source of cobalamin for growth, and this vitamin is synthesised only by bacteria; it is very likely that similar symbiotic interactions underpin algal productivity more generally.