Receptivity to transformative change in the Dutch urban water management sector.

Worldwide, the need for transformative change in urban water management is acknowledged by scientists and policy makers. The effects of climate change and developments such as urbanization, the European Water Framework Directive, and societal concerns about the sustainability of urban water system force the sector to adapt. In The Netherlands, a shift towards integration of spatial planning and water management can be observed. Despite major changes in water management policy and approach, changes in the physical urban water management infrastructure remain limited to incremental solutions and demonstration projects. Policy studies show that institutional factors and professional perceptions are important factors for application of innovations in urban water management. An online survey among Dutch urban water management professionals demonstrates that according to most respondents, optimization of the current system is sufficient to achieve both European and national objectives for sustainable urban water management. The respondents are most concerned with the effects of climate change on urban water systems. In contrast to current policy of the national government, priority factors that should be addressed to achieve a more sustainable urban water system are improving knowledge of local urban water systems, capacity building, developing trust between stakeholders, and improving involvement of elected officials and citizens.

GTRAP3-18 serves as a negative regulator of Rab1 in protein transport and neuronal differentiation.

Glutamate transporter associated protein 3-18 (GTRAP3-18) is an endoplasmic reticulum (ER)-localized protein belonging to the prenylated rab-acceptor-family interacting with small Rab GTPases, which regulate intracellular trafficking events. Its impact on secretory trafficking has not been investigated. We report here that GTRAP3-18 has an inhibitory effect on Rab1, which is involved in ER-to-Golg trafficking. The effects on the early secretory pathway in HEK293 cells were: reduction of the rate of ER-to-Golgi transport of the vesicular stomatitis virus glycoprotein (VSVG), slowed accumulation of a Golgi marker plasmid in pre-Golgi structures after Brefeldin A treatment and inhibition of cargo concentration of the neuronal glutamate transporter excitatory amino-acid carrier 1 (EAAC1) into transpor complexes in HEK293 cells, an effect that could be completely reversed in the presence of an excess of Rab1. In accordance with the known role of Rab1 in neurite formation, overexpression of GTRAP3-18 significantly inhibited the length of outgrowing neurites in differentiated CAD cells. The inhibitory effect of GTRAP3-18 on neurite growth was rescued by co-expression with Rab1, supporting the conclusion that GTRAP 3-18 acted by inhibiting Rab1 action. Finally, we hypothesized that expression of GTRAP3-18 in the brain shoul be lower at stages of active synaptogenesis compared to early developmental stages. This was the case as expression of GTRAP3-18 declined from E17 to P0 and adult rat brains. Thus, we propose a model where protein trafficking and neuronal differentiation are directly linked by the interaction of Rab1 and its regulator GTRAP3-18.

Identification of a novel intercellular structure in late-stage differentiating lens cells.

This study describes a novel intercellular structure in the adult bovine lens. In differential interference contrast images, the structure has the shape of a thickened torus or 'bagel' of 3-9 micrometer diameter and is contributed equally by 2 adjacent fibre cells. Due to its shape and location reaching into 2 neighbouring cells, the novel structure was termed 'intercellular torus' or 'bagel'. Intercellular bagels are present in a subset of late-stage lens fibre cells of the intermediate cortex, a considerable time after the cytoplasmic organelles have been broken down and the pyknotic nuclear remnants have disappeared. They are not present in deeper fibres. Our experiments show that intercellular bagels do not stain positive for DNA or RNAs, but are rich in lipids. Preliminary data indicate that the intercellular bagels contain calcium, suggesting that they might act as a place of transient Ca(2+) storage or sequestration after the intracellular organelles, such as the endoplasmatic reticulum, nuclear envelope, Golgi apparatus and mitochondria have been eliminated from the lens fibres during terminal differentiation.

Gap junctions containing alpha8-connexin (MP70) in the adult mammalian lens epithelium suggests a re-evaluation of its role in the lens.

A missense mutation in one of the three lens connexins, alpha8-connexin, has been recently shown to be the genetic basis of the zonular pulverant lens cataract. This connexin had been considered to be expressed only in lens fibre cells. The present studies show that alpha8-connexin is also expressed in the lens epithelial cell layer. For this study, the distribution of gap junctions in the adult bovine lens has been investigated by confocal immunofluorescence microscopy using antibodies against alpha8-connexin (MP70) and alpha1-connexin (Cx43). In addition to the anticipated localisation of alpha8-connexin to the broad faces of lens fibre cells as reported in other species, alpha8-connexin was also found colocalized with alpha1-connexin at plaques in the lateral epithelial-epithelial plasma membranes of the bovine lens. These data suggest that mixed alpha8-connexin/alpha1-connexin plaques are between epithelial cells at their apico-lateral plasma membranes, rather than between epithelial and fibre cells. Indeed, freeze fracture analyses of the epithelial-fibre cell interface failed to reveal gap junctions connecting the epithelium and the underlying fibre cells. Importantly, microdissection and subsequent immunoblotting of lens epithelium samples confirmed the immunolocalisation results. The data suggest mature mammalian lens epithelial cells could form either heteromeric, heterotypic and/or mixed homomeric-homotypic gap junctional complexes with unique physiological properties, an important point when considering the role of epithelial cell connexins in cataractogenesis.

Lens fibre cell differentiation - A link with apoptosis?

During the process of terminal differentiation, the fibre cells in the eye lens undergo many changes that are reminiscent of apoptotic/necrotic changes. Mitochondria, for instance, undergo permeability transition and nuclear degradation is accompanied by chromatin condensation, disintegration of the nucleolus, dissolution of the nuclear lamina, nuclear pore clustering and fragmentation of the DNA into oligonucleosomal fragments. As during apoptosis, members of the caspase family of proteases were shown to be active during fibre cell differentiation and Bcl-2 overexpression was demonstrated to block normal differentiation of lens cells. In this review, the current knowledge of the sequence of events during cell death is summarised and contrasted with events during lens fibre cell differentiation. Due to the numerous similarities between these processes, lens fibre cell differentiation is suggested to represent an attenuated form of cell death.

The eye lens cytoskeleton.

During lens cell differentiation there are a number of very characteristic morphological changes that occur. These include a 50- to 100-fold increase in cell length as the equatorial lens epithelial cells differentiate into fibre cells and the loss of the cellular organelles such as mitochondria, nuclei, Golgi apparatus and endoplasmic reticulum. Coincident with these changes are dramatic alterations in the organisation of the lens fibre cell cytoskeleton and in particular the lens-specific intermediate filament network comprising CP49 and filensin. Cell shape and cell polarisation as well as tissue integrity are all processes that depend upon the cytoskeleton and are therefore important to the lens. The unique aspects of the lenticular cytoskeleton are the subject of this review.

Changes in the nucleolar and coiled body compartments precede lamina and chromatin reorganization during fibre cell denucleation in the bovine lens.

Nuclear elimination accompanies differentiation in such specialized cell types such as erthyrocytes and lens fibre cells. It also accompanies apoptosis which has suggested that similar processes could operate in both. Denucleation occurs in the lens in order to reduce light scatter and this process is often disrupted in cataract. Using the adult bovine lens as a model system, nuclear changes accompanying denucleation are described with particular emphasis on the lamina, nucleolar and coiled body compartments in lens nuclei. Nuclear shape, chromatin reorganization and chromatin breakdown were also monitored to correlate the timing of events. Rearrangement of both A- and B-type nuclear lamins occurred in parallel with chromatin condensation and preceded changes in nuclear shape. The earliest changes detected in this study occurred in the coiled body and nucleolar compartments using coilin and fibrillarin antibodies respectively, suggesting that a shutdown in transcription is an early event in denucleation. Fibrillarin redistributed from an open floret pattern to several condensed spots which gradually decreased in intensity and eventually disappeared. Coilin, however, was localized in several microfoci prior to being reorganized into fewer larger foci. Prior to chromatin condensation, coilin redistributed to the nucleolar compartment and was absent from nuclei where chromatin had begun to condense. Such nuclei were positive by TUNEL staining. In contrast to the nucleus, mitochondrial degradation in lens fibre cells was a rapid process and involved a relatively sharp transition between positive and negative fibre cells for two mitochondrial specific markers, BAP 37 and prohibitin. A link between the changes in the nuclear lamina and chromatin with the initiation of mitochondrial fragmentation was also observed. Therefore, it is possible that the signal for the initiation of denucleation could originate from the mitochondria as proposed for apoptosis. Differences between apoptosis and lens fibre cell denucleation were noted and included the timescale of nuclear changes as well as the persistence of a nuclear remnant. These studies suggest that transcriptional shutdown precedes lamina reorganization and chromatin breakdown during lens fibre cell denucleation.

Identification of dihydrothiazoles in urine of male mice.

The compounds 2-isopropyl-4,5-dihydrothiazole and 2-sec-butyl-4,5-dihydrothiazole were identified in urine of male mice. Their excretion in mouse urine is sex-dependent. In the urine of female mice the two dihydrothiazoles are either absent or present only in trace amounts. The analytical procedure includes the adsorption of the volatile mouse urine constituents on Tenax GC, their gas chromatographic separation and the detection of the sulfur compounds by the sulfur-specific detector. The identified compounds were synthesized. Natural and synthetic compounds had the same mass spectrometric properties and retention data.