Targeted mutagenesis of the Sap47 gene of Drosophila: Flies lacking the synapse associated protein of 47 kDa are viable and fertile

Background  

Conserved proteins preferentially expressed in synaptic terminals of the nervous system are likely to play a significant role in brain function. We have previously identified and molecularly characterized the Sap47 gene which codes for a novel synapse associated protein of 47 kDa in Drosophila. Sequence comparison identifies homologous proteins in numerous species including C. elegans, fish, mouse and human. First hints as to the function of this novel protein family can be obtained by generating mutants for the Sap47 gene in Drosophila.     

Production of certified reference materials for the detection of genetically modified organisms

Certified reference materials (CRMs) are an essenIial tool in the quality assurance of analytical measurements. They are produced, certified, and used in accordance with relevant ISO (International Organization for Standardization) and BCR (Community Bureau of Reference) guidelines. The Institute for Reference Materials and Measurements (IRMM; Geel, Belgium) has produced the first powdery genetically modified organism (GMO) CRMs in cooperation with the Institute for Health and Consumer Protection (Ispra, Italy). Until now, different weight percentages in the range of 0-5% for 4 GMOs in Europe were produced and certified: Bt (Bacillus thuringiensis)-11 and Bt-176 maize, Roundup Ready soybean, and MON810 maize. Bt-11 and Bt-176 maize and Roundup Ready soybean were produced by IRMM on behalf of Fluka Chemie AG (Buchs, Switzerland). Characterization of used base material is the first step in production and is especially important for GMO CRMs. The production of powdery GMO CRMs and methods used for production control are described. Thorough control of homogeneity and stability are essential for certification of reference materials and ensure validity of the certificate for each bottle of a batch throughout a defined shelf-life. Because production of reference materials and their maintenance are very labor- and cost-intensive tasks, the usefulness of new types of GMO CRMs must be estimated carefully.     

The nexus between alternatives assessment and green chemistry: supporting the development and adoption of safer chemicals

ABSTRACT

Alternatives assessment and green chemistry share a common goal of supporting the transition to safer, more sustainable chemicals, materials, and products. Yet the two fields, and their respective scientific communities, are not well integrated. To better understand the nexus between alternatives assessment and green chemistry as complementary approaches to support the development and adoption of safer, more sustainable chemicals for specific functional uses, this article discusses the foundations of the two fields and examines two case examples in which companies have utilized the tools and approaches of both disciplines in developing safer chemical solutions. This research demonstrates the importance and utility of the overlapping skillsets and tools of the two disciplines and the potential benefit of educational opportunities and collaborative spaces in jointly strengthening both fields. Additionally, the literature and case examples identify a number of research and practice needs that would bolster the application of both alternatives assessment and green chemistry in supporting the transition to safer, more sustainable chemistry, including: clearer definitions and criteria of what is ‘safer’; improved approaches to evaluate potential unintended consequences of chemical applications; and more effective tools to evaluate toxicity, consider inherent exposure trade-offs, and combine multiple attributes to make an informed decision.     

Gas chromatography-olfactometry analysis of the volatile compounds of two commercial Irish beef meats

The volatile flavour compounds of two commercial Irish beef meats (labelled as conventional and organic) were evaluated by gas chromatography-olfactometry and were identified by gas chromatography-mass spectrometry. The volatile compounds were isolated in a model mouth system. Gas chromatography-olfactometry was performed by a group of eight assessors using the detection frequency methodology. The odours of the detected compounds were described as well. Eighty-one volatile compounds were identified, 11 compounds of which possessed odour activity in the first beef sample and 14 of which in the second meat sample. Ten volatile flavour compounds were common to both: methanethiol, dimethyl sulphide, 2-butanone, ethyl acetate, 2- and 3-methylbutanal, an unknown compound, 2-octanone, decanal and benzothiazole. Two unknown compounds were only detected in the first sample while 2,3-pentanedione, 4-methyl-3-penten-2-one, 2-heptanone, dimethyl trisulphide and nonanal were only perceived in the second beef. Significant differences in terms of detection frequency, odour characteristics and in nature of the volatile flavour compounds were emphasised between the two samples.     

Vacuum-ultraviolet photochemically initiated modification of polystyrene surfaces: chemical changes

Fourier-Transform infrared (FTIR) spectroscopy and surface energy analysis (contact angle measurements) have been performed as a means of identification and quantification of the functionalization of polystyrene surfaces upon vacuum ultraviolet- (VUV-) photochemically initiated oxidation. Photochemical oxidation was performed in the presence of water vapor and molecular oxygen using a pulsed Xe2-excimer radiation source (lambda(exc): 172 nm). Surface oxidation was studied as a function of two parameters: irradiation time and distance between sample and radiation source. During the first 1-2 min of irradiation, an increase of the concentrations of hydroxyl (OH) and carbonyl (C=O) groups on the surface was observed, both reaching limiting values. As expected, the rate of oxidation diminished exponentially with increasing distance between the radiation source and the surface of the polystyrene film. Changes in the surface energy due to the introduction of these polar (i.e. OH and C=O) groups were also determined. The densities of the functional groups decreased upon washing with acetonitrile, and analysis of the washing solution by means of gas chromatography-mass spectrometry (GC-MS) revealed the presence of a large number of products. The application of pulsed Xe2-excimer radiation sources as a valuable alternative to conventional means (i.e. laser and plasma) for the photochemical oxidation and surface modification of polystyrene is discussed.     

Microstructure analysis of a carbon-carbon composite using argon ion etching.

The microstructure of carbon-carbon composites obtained by chemical vapor infiltration of a carbon fiber felt was comparatively studied by reflection light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and laser scanning confocal microscopy (LSCM). Ar+ ion etching was used to reveal and distinguish structural units of the pyrolytic carbon matrix. Mechanically polished samples, polished and subsequently ion etched samples, and fractured samples were compared. The values of surface roughness and surface height after polishing or after polishing and subsequent etching determined by AFM and LSCM correlate well with the degree of texture of the matrix layers obtained by polarized light microscopy and selected area electron diffraction. The carbon matrix is composed of structural units or "cells," which contain a carbon fiber and a sequence of several differently textured layers around each fiber. Within high-textured layers columnar grains are well recognizable using polarized reflection light microscopy and confocal microscopy. The size of depressions within high-textured carbon layers found by AFM after ion etching correlates well with the size of differently tilted domains detected by both TEM and SEM.     

Ion trap MS/MS of polychlorinated dibenzo-p-dioxins and dibenzofurans: confirming the concept of the molar response

It has been shown that the concept of molar response, which is applicable to single ion monitoring of M⁺, can also be employed for ion trap MS/MS measurements, simplifying the determination of PCDD/PCDF by an extended IDA approach.     

Ion trap MS/MS of polychlorinated dibenzo-p-dioxins and dibenzofurans: confirming the concept of the molar response

It has been shown that the concept of molar response, which is applicable to single ion monitoring of M⁺, can also be employed for ion trap MS/MS measurements, simplifying the determination of PCDD/PCDF by an extended IDA approach. Received: 22 April 1997 / Revised: 16 June 1997 / Accepted: 18 June 1997     

The influence of the molecular weight distribution of network chains on the mechanical properties of polymer networks

End-linked poly(dimethylsiloxane) (PDMS) networks with different molecular weight distributions (MWD) of the primary chains were prepared and investigated by isothermal stress-strain measurements. We found a lowering of the elastic modulus with increasing broadness of the MWD. The observed range of the moduli seems not to be restricted to the region limited by the classical models of rubber elasticity. This result is based on our own experimental investigations and on a reanalysis of data taken from the literature. In the case of nearly monodisperse distributions (M _n /M _w 1) the effect of configurational restrictions of the network strands probably dominates. In the opposite case (M _n /M _w 1), we discuss that spatial clustering of the crosslinks may reduce the effective number of elastically active network junctions.