| 31. |
- Bras, H., et al.
(författare)
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An investigation of local actions of ionophoretically applied DOPA in the spinal cord
- 1988
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 71, s. 447-449
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Tidskriftsartikel (refereegranskat)abstract
- Methyl-L-DOPA (L-beta-3,4-dihydroxyphenylalanine methyl ester, hydrochloride) was applied ionophoretically to investigate its effects on neurones at various locations in the cat spinal cord. Its actions were tested on monosynaptic field potentials evoked from group I and group II muscle afferents in midlumbar segments. Methyl-L-DOPA has been found to depress field potentials evoked from group II afferents in the ventral horn and in the intermediate zone but not in the dorsal horn, nor field potentials evoked from group I afferents. Its effects were the same as those of systemically applied L-DOPA (L-beta-3,4-dihydroxyphenylalanine), although weaker. © 1998 Springer-Verlag.
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| 32. |
- Breidbach, Olaf, et al.
(författare)
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Proctolin-immunoreactive neurons persist during metamorphosis of an insect: A developmental study of the ventral nerve cord of Tenebrio molitor(Coleoptera)
- 1989
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Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 257:1, s. 217-225
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Tidskriftsartikel (refereegranskat)abstract
- Proctolin-immunoreactive neurons in all neuromers of the ventral nerve cord of Tenebrio molitor L. have been quantitatively demonstrated and mapped throughout metamorphosis. Each neuromer contains an anterior and a posterior group of neurons with light and dark staining properties as revealed by peroxidase-antiperoxidase labeling. Serial homologous subsets of dark staining neurons with central and peripheral projections have been identified and found to persist during morphogenetic changes from the larva to the adult. Most neurons maintain their topological and structural characteristics throughout metamorphosis. The identified proctolin-immunoreactive neurons exhibit structures similar to those described in other insect species; some may correspond known motoneurons.
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| 33. |
- Brodelius, Peter, et al.
(författare)
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Permeabilization of Cultivated Plant Cells by Electroporation for Release of Intracellularly Stored Secondary Products
- 1988
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Ingår i: Plant Cell Reports. - 0721-7714 .- 1432-203X. ; 7:3, s. 186-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant cell suspension cultures producing secondary metabolites have been permeabilized for product release by electroporation. The two cell cultures studied, i.e. Thalictrum rugosum and Chenopodium rubrum, require about 5 and 10 kV cm–1, respectively, for complete permeabilization (release of all the intracellularly stored product). The number of electrical pulses and capacitance used had a relatively limited effect on product release while the viability of the cells was strongly influenced by the latter. Conditions for complete product release resulted in total loss of viability of the cells after treatment. The release of product from immobilized cells was also achieved by electroporation. Cells entrapped in alginate required less voltage for permeabilization than free or agarose entrapped cells.
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| 34. |
- Brodelius, Peter
(författare)
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Permeabilization of Plant Cells for Release of Intracellularly Stored Products: Viability Studies
- 1988
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Ingår i: Applied Microbiology and Biotechnology. - 0175-7598 .- 1432-0614. ; 27, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- The effects of various chemical substanceson the permeability of plasma membranesand tonoplasts of three suspension cultures (Catharanthusroseus, Thalictrum rugosum and Chenopodiumrubrum) have been studied. The permeabilityof the plasma membrane is monitoredby measuring the activity of the cytosolic enzymeisocitrate dehydrogenase and the permeability ofthe tonoplast is measured by determining the releaseof substances stored in the vacuoles (inorganicphosphate, berberine and betanin for thethree cell lines, respectively). The minimum concentrationrequired for quantitative release of vacuolarproducts have been established for five differentpermeabilization agents. Cell viability islost upon permeabilization except for treatmentof Catharanthus roseus with DMSO and Triton X-100.
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| 35. |
- Burström, Lage, et al.
(författare)
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Mechanical energy absorption in human hand-arm exposed to sinusoidal vibration
- 1988
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Ingår i: International Archives of Occupational and Environmental Health. - 0340-0131 .- 1432-1246. ; 61:3, s. 213-216
-
Tidskriftsartikel (refereegranskat)abstract
- A possible basis for risk assessment of human exposure to vibration when using hand-held tools may be to determine the amount of mechanical energy that is absorbed by the hand-arm system. The aim of this investigation was to study the absorption of mechanical energy in the human hand-arm system during exposure to sinusoidal vibration within the frequency range of 20 to 1500 Hz. A handle, specially designed for this type of experiments, was used during the measurements. The influence of various experimental conditions, such as three different hand-arm postures, grip force (25–75 N) and vibration levels (27–53 mm/srms), were studied on eight subjects. The outcome clearly shows that the energy absorption properties of the human hand-arm system are more or less dependent on all of the experimental conditions studied, but mainly to the frequency of the vibration stimuli. Furthermore, the results indicate a non-linear relationship between the energy absorbed and all other variables studies.
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| 36. |
- Byström, Anders S., et al.
(författare)
-
A functional analysis of the repeated methionine initiator tRNA genes (IMT) in yeast
- 1989
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Ingår i: Molecular General Genetics. - 0026-8925 .- 1432-1874. ; 216:2-3, s. 276-286
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Tidskriftsartikel (refereegranskat)abstract
- Standard laboratory yeast strains have from four to five genes encoding the methionine initiator tRNA (IMT). Strain S288C has four IMT genes with identical coding sequences that are colinear with the RNA sequence of tRNA(IMet). Each of the four IMT genes from strain S288C is located on a different chromosome. A fifth IMT gene with the same coding sequence is present in strain A364A but not in S288C. By making combinations of null alleles in strain S288C, we show that each of the four IMT genes is functional and that tRNA(IMet) is not limiting in yeast strains with three or more intact genes. Strains containing a single IMT2, 3 or 4 gene grow only after amplification of the remaining IMT gene. Strains with only the IMT1 gene intact are viable but grow extremely slow; normal growth is restored by the addition of another IMT gene by transformation, providing a direct test for IMT function.
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| 37. |
- Byström, Anders S, et al.
(författare)
-
The structural gene (trmD) for the tRNA(m1G)methyltransferase is part of a four polypeptide operon in Escherichia coli K-12
- 1982
-
Ingår i: Molecular General Genetics. - : Springer-Verlag New York. - 0026-8925 .- 1432-1874. ; 188:3, s. 447-454
-
Tidskriftsartikel (refereegranskat)abstract
- The trmD gene, which is the structural gene for the tRNA(m1G)-methyltransferase, is shown to be part of a polycistronic operon. A 4.6 kb SalI-EcoRI chromosomal DNA fragment contains the trmD gene (Byström and Björk 1982). Subclonings, deletion mapping and Tn5 insertions into plasmid pBY03 have established the gene organization of the trmD area on the Escherichia coli chromosome. The different plasmid derivatives were analysed for expression of protein products using the minicell system. Such analyses established the organisation of genes encoding six polypeptides to be SalI1-48 K-13 K-25 K-31 K-15 K-16 K-EcoRI1. The 31 K polypeptide was shown to be the tRNA(m1G)methyltransferase. The trmD operon encodes for four polypeptides; 13 K-25 K-31 K(trmD)-15 K and the direction of transcription is from 13 K (promoter proximal) to 15 K (promoter distal). However, there might be a weak internal promoter between the trmD gene and the gene encoding the 15 K product. The level of expression from this operon in the minicell system does not seem to follow normal polarity since we observed high expression of 13 K, 25 K, and 15 K products but low expression of the internal trmD gene.
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| 38. |
- Bååth, Erland, et al.
(författare)
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Fungal populations in podzolic soil experimentally acidified to simulate acid-rain
- 1984
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Ingår i: Microbial Ecology. - 1432-184X. ; 10:3, s. 197-203
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe effect of experimental acidification on the soil microfungalcommunity was studied in the humus layer of a coniferous forest in northern Sweden. The study was made 4 years after the last application of sulfuric acid. Fungal species composition was altered by treatments of 100 and 150 kg sulfuric acid ha-1 each year for 6 years, yet no differences were found between the control treatment and an application of 50 kg ha-1. The abundance of Penicillium spinulosum and Oidiodendron cf. echinulatum II increased with increasing rates of acid application, whereas only small changes were found for other isolated fungal taxa. Soil respiration rate and fluorescein diacetate (FDA)-active fungal biomass were significantly different from the control treatment at all 3 levels of acidification.
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| 39. |
- Bååth, L.B. 1948-, et al.
(författare)
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The Radio Fine Structure of the BL Lacertae Objects AO0235+164, 0735+178, BL Lac, 1749+701, Mk 421 and 3C 66 A at 5 GHz
- 1981
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 96:1-2, s. 316-324
-
Tidskriftsartikel (refereegranskat)abstract
- Very long baseline interferometer observations at 4997 MHz (lambda = 6 cm) on European and intercontinental baselines with lengths up to 1.35 108lambda have been used to probe the milliarc s structure of the BL Lacertae objects AO 0235+164, 0735+178, BL Lac, 1749+701, Mk 421, and 3C 66A. Two sets of observations are reported, made in November 1978 and March 1979. AO 0235+164 and 0735+178 both showed structures consisting of a very bright, unresolved core and a jet-like component extending ˜5".4 10-3 along position angle ˜20° and ˜4".2 10-3 along position angle ˜45°, respectively. AO 0235+164 contained more than 98% of the total flux density within a diameter of ≲ 36" 10-3. BL Lac, 1749+701 and Mk 421 all showed evidence for a complex structure of several components, including an unresolved core. 3 C 66A was elongated along position angle ˜ -45°.
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| 40. |
- Bååth, L.B. 1948-, et al.
(författare)
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Time-Dependent Radio Fine Structure of the Compact Sources NRAO 150 and 4C 39.25
- 1980
-
Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 86:3, s. 364-372
-
Tidskriftsartikel (refereegranskat)abstract
- Very long baseline interferometer observations at 7.85 GHz have been used to probe the milliarcsecond structure of the unidentified, very compact radio source NRAO 150 and QSO 4 C 39.25. NRAO 150 exhibited no structural variations from 1972 to the end of 1974. A model with two circular Gaussian components fits the data well. NRAO 150 had a flux density of 7.6 plus or minus 0.5 Jy in the compact component; 4 C 39.25 showed a two-component structure, the components having a separation of (2.02 plus or minus 0.05 arc sec) x 10 to the -3rd power. The upper bound on the speed of transverse separation is 0.0001 arc sec per year or less than 2.7 c. From the spectrum there are also indications of a third, larger component.
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