The light-harvesting antenna of Chlorobium tepidum: Interactions between the FMO protein and the major chlorosome protein CsmA studied by surface plasmon resonance

Green sulfur bacteria possess two external light-harvesting antenna systems, the chlorosome and the FMO protein, which participate in a sequential energy transfer to the reaction centers embedded in the cytoplasmic membrane. However, little is known about the physical interaction between these two antenna systems. We have studied the interaction between the major chlorosome protein, CsmA, and the FMO protein in Chlorobium tepidum using surface plasmon resonance (SPR). Our results show an interaction between the FMO protein and an immobilized synthetic peptide corresponding to 17 amino acids at the C terminal of CsmA. This interaction is dependent on the presence of a motif comprising six amino acids that are highly conserved in all the currently available CsmA protein sequences.     

Synthesis and optical resolution of an allenoic acid by diastereomeric salt formation induced by chiral alkaloids

A synthetic procedure for the preparation of 4-cyclohexyl-2-methyl-buta-2,3-dienoic acid in the two optically active forms has been developed. Synthesis of the racemic allenoic acid was made by an efficient route with good overall yield. Resolution of the enantiomers was achieved by forming the cinchonidine and cinchonine diastereomeric salt, respectively, and the enantiomers were isolated in up to 95% enantiomeric excess. The absolute configuration of the allenoic acid was determined by X-ray crystallography.     

Experiences of Borna disease virus infection in Sweden

In the early 1970s a fatal neurological disorder in cats was reported in the areas around Lake M?laren in central Sweden. The major signs were hind-leg ataxia, as well as absence or marked decrease in postural reactions and in some cases behavioural changes. The pathology of the disorder was characterized as a non-suppurative meningoencephalomyelitis, but the etiology was not determined. Almost twenty years later, the disorder now known as staggering disease (SD), was further characterized both clinically and pathologically. The same histopathological picture was seen as in the previous study, with inflammatory nodules, neuronal degeneration and perivascular cuffs mainly consisting of lymphocytes. The most severe inflammatory changes were seen in the grey matter of the brain stem, basal ganglia and hippocampus. Clinically the same major neurological signs were seen. Although the cats were examined for several known infectious agents causing central nervous system (CNS) disturbances, no etiological cause of SD was determined.     

Genetic manipulation of adult mouse neurogenic niches by in vivo electroporation

Targeted ectopic expression of genes in the adult brain is an invaluable approach for studying many biological processes. This can be accomplished by generating transgenic mice or by virally mediated gene transfer, but these methods are costly and labor intensive. We devised a rapid strategy that allows localized in vivo transfection of plasmid DNA within the adult neurogenic niches without detectable brain damage. Injection of plasmid DNA into the ventricular system or directly into the hippocampus of adult mice, followed by application of electrical current via external electrodes, resulted in transfection of neural stem or progenitor cells and mature neurons. We showed that this strategy can be used for both fate mapping and gain- or loss-of-function experiments. Using this approach, we identified an essential role for cadherins in maintaining the integrity of the lateral ventricle wall. Thus, in vivo electroporation provides a new approach to study the adult brain.     

Simultaneous use of electrochemistry and chemiluminescence to detect reactive oxygen species produced by human neutrophils

A novel approach for the simultaneous optical and electrochemical detection of biologically produced reactive oxygen species has been developed and applied. The set-up consists of a luminol-dependent chemiluminescence assay combined with two amperometric biosensors sensitive to superoxide anion radicals (O(2)(-)) and hydrogen peroxide (H(2)O(2)), respectively. The method permits direct, real-time in vitro determination of both extra- and intracellular O(2)(-) and H(2)O(2) produced by human neutrophil granulocytes. The rate of O(2)(-) production by stimulated neutrophils was calculated to about 10(-17)mol s(-1) per single cell. With inhibited NADPH oxidase, a distinct extracellular release of H(2)O(2) instead of O(2)(-) was obtained from stimulated neutrophils with the rate of about 3 x 10(-18)mol s(-1) per single cell. When the H(2)O(2) release was discontinued, fast H(2)O(2) utilisation was observed. Direct interaction with and possibly attachment of neutrophils to redox protein-modified gold electrodes, resulted in a spontaneous respiratory burst in the population of cells closely associated to the electrode surface. Hence, further stimulation of human neutrophils with a potent receptor agonist (fMLF) did not significantly increase the O(2)(-) sensitive amperometric response. By contrast, the H(2)O(2) sensitive biosensor, based on an HRP-modified graphite electrode, was able to reflect the bulk concentration of H(2)O(2), produced by stimulated neutrophils and would be very useful in modestly equipped biomedical research laboratories. In summary, the system would also be appropriate for assessment of several other metabolites in different cell types, and tissues of varying complexity, with only minor electrode modifications.     

An analysis of hatching success in the great reed warbler Acrocephalus arundinaceus

Hatching success is a potentially important fitness component for avian species. Previous studies of hatching success in natural populations have primarily focused on effects of inbreeding but a general understanding of variation in hatching success is lacking. We analyse data on hatching success in a population of great reed warblers Acrocephalus arundinaceus in Lake Kvismaren in south central Sweden. The effects of a range of covariates, including three measures of inbreeding as well as effects of classifications in the data (such as identities of individuals), on hatching success are analysed simultaneously. This is done by means of fitting Bayesian binomial mixed models using Markov chain Monte Carlo methods. Using random effects for each individual parent we check for unexplained variation in hatching success among male and female individuals and compare it to effects of covariates such as degree of inbreeding. Model selection showed that there was a significant amount of unexplained variation in hatching probability between females. This was manifested by a few females laying eggs with a substantially lower hatching success than the majority of the females. The deviations were of the same order of magnitude as the significant effect of parent relatedness on hatching success. Whereas the negative effect of parent relatedness on hatchability is an expression of inbreeding, the female individual effect is not due to inbreeding and could reflect maternal effects, that females differ in fertilisation and/or incubation ability, or an over representation of genetic components from the female acting on the early developing embryo.