Nonlinear mirror modelocking of a bounce geometry laser.

We present the investigation of nonlinear mirror modelocking (NLM) of a bounce amplifier laser. This technique, a potential rival to SESAM modelocking, uses a nonlinear crystal and a dichroic mirror to passively modelock a Nd:GdVO(4) slab bounce amplifier operating at 1063nm. At 11.3W, we present the highest power achieved using the NLM technique, using type-II phase-matched KTP, with a pulse duration of 57ps. Using type-I phase-matched BiBO, modelocking was achieved with a shorter pulse duration of 5.7ps at an average power of 7.1W.

Size and cell number of the utricle in kinetotically swimming fish: a parabolic aircraft flight study.

Humans taking part in parabolic aircraft flights (PAFs) may suffer from space motion sickness (SMS, a kinetosis). Since it has been repeatedly shown earlier that some fish of a given batch also reveal a kinetotic behavior during PAFs (especially so-called spinning movements and looping responses) and due to the homology of the vestibular apparatus among all vertebrates, fish can be used as model systems to investigate the origin of susceptibility to motion sickness. Therefore, we examined the utricular maculae (they are responsible for the internalization of gravity in teleosteans) of fish swimming kinetotically at microgravity in comparison with animals from the same batch who swam normally. On the histological level, it was found that the total number of both sensory and supporting cells of the utricular maculae did not differ between kinetotic animals as compared to normally swimming fish. Cell density (sensory and supporting cells/100 micrometers2), however, was reduced in kinetotic animals (p<0.0001), which seemed to be due to malformed epithelial cells (increase in cell size) of the kinetotic specimens. Susceptibility to kinetoses may therefore originate in malformed sensory epithelia.

Susceptibility to motion sickness in fish: a parabolic aircraft flight study.

Juvenile swordtail fish and larval cichlids were subjected to parabolic aircraft flights (PAFs) and individually observed. After the PAFs, inner ear otoliths and sensory epithelia were examined on the light microscopical level. Otolith asymmetry (differences in otolith size between the left and the right side) was especially pronounced in those fish, who exhibited a kinetotic behaviour (e.g., spinning movements) during microgravity. This speaks in favour of a theoretical concept according to which susceptibility to space motion sickness in humans may be based on asymmetric inner ear stones. The cell density of sensory epithelia was lower in kinetotic animals as compared to normally swimming fish. Thus, asymmetric otoliths can cause kinetosis in fish during PAFs, but susceptibility to kinetosis may also be based on an aberrative inner ear morphology.

Nucleotide sequence of the gene for ribosomal protein S17 from Dictyostelium discoideum.

The nucleotide sequence of the gene for the Dictyostelium homologue of eukaryotic ribosomal protein S17 has been assembled from cDNA and genomic DNA clones. The predicted primary structure of the S17 protein displays a similar level of sequence identity with its counterparts from higher eukaryotes (53%) as other Dictyostelium ribosomal proteins. Although Dictyostelium genes usually are organized in a rather simple manner, the rps17 gene harbors two introns. One of them, located immediately 3' from the ATG initiator codon, appears to be ubiquitously conserved in eukaryotic rps17 genes.

Morphogenetic differentiation of the brain of the cichlid fish, Oreochromis mossambicus.

In the present study, the morphogenetic brain differentiation of the cichlid fish, Oreochromis mossambicus, is described using conventional histological methods. Cross sections through the developing brain of fish larvae aged 2, 8, 10, 12 and 20 days post hatch, and of adults, were investigated in order to characterize individual brain regions and nuclei, especially parts of the diencephalon, brainstem and cerebellum during critical phases of early larval development. The above age stages conform to the following developmental (larval) stages: 2 days = stage 7, 8 days = stage 10, 10 days = stage 11, 12 days = stage 12 and 20 days = stage 15. An increasing number of nuclei and a volumetric increase in size of individual brain parts in older fish larvae and in adult fish were registered. In the optic tectum, an extreme lateral extension was found in contrast to an insignificant increase in stratification at this developmental time. In one part of the brainstem, the Area octavolateralis (AOL) of 2-day-old larvae, only a few undifferentiated perikarya were found and in the AOL of 20-day-old animals up to 5 nuclei, versus 7 AOL-nuclei in adult fish brain, could be discriminated. Variations in the position of the Mauthner cell versus the surrounding and corresponding brain nuclei were shown during the ontogenetic development. The results were presented by cartoon portrayals of the relationships between characteristic nuclei and by drawings of specific brain cross sections in different aged larval stages.

A ribosomal calmodulin-binding protein from Dictyostelium.

Using 125I-calmodulin as a probe, we have recently identified specific Ca2+/calmodulin-binding proteins in cell extracts from the cellular slime mold, Dictyostelium discoideum: a major 22-kDa activity, a soluble 78/80-kDa protein, and several membrane-associated high Mr proteins (Winckler, T., Dammann, H., and Mutzel, R. (1991) Res. Microbiol. 142, 509-519). cDNA clones for at least two of these proteins have been isolated by ligand screening of a lambda gt11 prophage expression library. Antibodies directed against the lacZ-cDNA-encoded fusion protein from one of the clones recognized a single 22-kDa component in D. discoideum extracts which comigrated with the endogenous 22-kDa calmodulin-binding protein. The cDNA-derived nucleotide sequence predicts a protein of Mr 21,659 with 56% sequence identity (69% homology) with rat ribosomal protein L19. The endogenous 22-kDa calmodulin-binding activity was associated with ribosomes. It was found to be an integral constituent of the large ribosomal subunit, since it cosedimented with 60 S ribosomal subunits in sucrose density gradients in the presence of 0.5 M NH4Cl. Our observations point to a physiological role for calmodulin in the Ca2+ regulation of eukaryotic protein synthesis. Support for this comes from recent studies showing inhibition of protein synthesis by calmodulin antagonists in Ehrlich ascites tumor cells (Kumar, R. V., Panniers, R., Wolfman, A., and Henshaw, E.C. (1991) Eur. J. Biochem. 195, 313-319).

Determination of hippuric acid and furanic acid in serum of dialysis patients and control persons by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanic acid) and hippuric acid in human serum is described. Quantitative data were obtained from 20 blood donors, 26 non-dialysis patients and 41 dialysis patients. In healthy persons hippuric acid ranged from 0.2 to 0.6 mg/dl, furanic acid from 0.13 to 0.53 mg/dl. In dialysis patients the mean concentration of hippuric acid was elevated to 17.2 mg/dl (range 1.7-50.8 mg/dl) and the mean concentration of furanic acid was elevated to 1.89 mg/dl (range 0.17-6.45 mg/dl). In patients without renal insufficiency the concentrations were not elevated. These data are in accordance with previous data obtained by gas chromatographic methods. Preliminary results indicate that hippuric acid and furanic acid may be more specific parameters than other uremic retention products, and better indicators for the need for dialysis treatment than urea or creatinine.