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31.
Andrea Schmidt Stephanie Bringer-Meyer Karl Poralla Hermann Sahm 《Applied microbiology and biotechnology》1989,30(2):170-175
Summary The influence of different primary aliphatic alcohols on the activities of two key enzymes in hopanoid biosynthesis of Zymomonas mobilis was investigated. By use of 14C- and 3H-labelled substrates the enzymes 3-hydroxy-3-methylglutaryl-CoA-reductase and squalene-hopenecyclase were detected with activities of 1.6 pmol x (min x mg protein)-1 and 2.3 pmol x- (min x mg protein)-1, respectively. Cells grown in the presence of 6% (v/v) ethanol did not show higher activities of these enzymes than cells grown in the presence of 1% (v/v) ethanol. Furthermore, 3-hydroxy-3-methylglutaryl-CoA-reductase was not activated by ethanol. However, ethanol activated the squalene-hopene-cyclase when added to the enzyme test system. Besides ethanol, propanol also had a positive effect on the squalene-hopene-cyclase: the enzyme's activity increased 1.7-fold in the presence of either alcohol at a concentration of 6% (v/v). This corresponded with a similar increase of hopanoid content of whole cells when grown in the presence of 6% (v/v) added ethanol or propanol. These results indicated that the squalene-hopene-cyclase has a regulatory function in the alcohol dependent hopanoid biosynthesis of Z. mobilis.Abbreviation HMG-CoA-reductase
3-hydroxy-3-methylglutaryl-coenzyme A-reductase 相似文献
32.
J R López L E Brice?o G Cordovez V Sánchez N Linares 《General physiology and biophysics》1989,8(2):91-98
Carnitine is required for the transport of activated long chain fatty acids through the mitochondrial inner membrane. We measured the intracellular free calcium concentration [( Ca2+]i) by means of a calcium selective microelectrode in skeletal muscle biopsies obtained from nine patients in which myopathic carnitine deficiency (MCD) was diagnosed, and from six subjects with no evidence of neuromuscular disease. Intact intercostal muscle bundles were dissected and then split for electron microscopic studies and electrophysiological measurements. The [Ca2+]i in muscle fibers from MCD patients was 0.46 +/- 0.02 mumol.l-1 (mean +/- SEM) and 0.10 +/- 0.01 mumol.l-1 in control subjects. At the electron microscopic level, the predominant abnormality was the presence of lipid vacuoles between the myofibrils. These results show that in patients with myopathic carnitine deficiency there is a significant increase in the resting myoplasmic calcium concentration which might be related to a malfunction of some mechanisms responsible for the homeostasis of intracellular calcium. 相似文献
33.
Dr. Andrea Novicki 《Cell and tissue research》1989,255(3):641-644
Summary The singing muscles of the katydid Neoconocephalus robustus develop adult ultrastructure late in the last nymphal instar and during the first few days of adult life. The ultrastructural changes during early adulthood were not affected by unilateral axotomy shortly after the adult molt. Both denervated and innervated muscles developed adult proportions of mitochondria, myofibril, and sarcoplasmic reticulum and transverse tubules. 相似文献
34.
35.
Daniele Arobba Andrea Quaglia Paolo Panagia Paolo Minuti Sergio Innocenti Pier Luigi Odda 《Aerobiologia》1988,4(1-2):38-46
Riassunto Sono state rilevate durante un monitoraggio aerobiologico effettuato a Pietra Ligure (Savona) nel corso del 1987 le concentrazioni
polliniche di 50 taxa ed è stata valutata l'influenza relativa dei fattori meteorologici. Le osservazioni palinologiche sono
state rapportate alle concentrazioni sieriche delle IgE specifiche, alla reattività bronchiale specifica ed aspecifica valutate
in 101 pazienti allergici (rinitici ed asmatici), sensibilizzati a Graminaceae ed Urticaceae (Parietaria) al fine di riconoscere
correlazioni tra le caratteristiche aerobiologiche di questi allergeni edi meccanismi patogenetici che sostengono la reattività
bronchiale.
相似文献
36.
beta-Methyleneaspartate, a specific inhibitor of aspartate aminotransferase (EC 2.6.1.1.), was used to investigate the role of the malate-aspartate shuttle in rat brain synaptosomes. Incubation of rat brain cytosol, "free" mitochondria, synaptosol, and synaptic mitochondria, with 2 mM beta-methyleneaspartate resulted in inhibition of aspartate aminotransferase by 69%, 67%, 49%, and 76%, respectively. The reconstituted malate-aspartate shuttle of "free" brain mitochondria was inhibited by a similar degree (53%). As a consequence of the inhibition of the aspartate aminotransferase, and hence the malate-aspartate shuttle, the following changes were observed in synaptosomes: decreased glucose oxidation via the pyruvate dehydrogenase reaction and the tricarboxylic acid cycle; decreased acetylcholine synthesis; and an increase in the cytosolic redox state, as measured by the lactate/pyruvate ratio. The main reason for these changes can be attributed to decreased carbon flow through the tricarboxylic acid cycle (i.e., decreased formation of oxaloacetate), rather than as a direct consequence of changes in the NAD+/NADH ratio. Malate/glutamate oxidation in "free" mitochondria was also decreased in the presence of 2 mM beta-methyleneaspartate. This is probably a result of decreased glutamate transport into mitochondria as a result of low levels of aspartate, which are needed for the exchange with glutamate by the energy-dependent glutamate-aspartate translocator. 相似文献
37.
Summary The presence of house dust mites and storage mites in dumpsters was investigated in 3 different areas of Venice hinterland. The aim of this study was to find a relationship between some reported respiratory symptoms among 6 workers who were responsible for moving the dumpsters to the truck and the bio-aerosol released from such operation. These symptoms were closely related to the work and after allergological evaluation we found sensitisation to house dust mites in all 6 employees. The mine exposure in the workplace was assessed by a standardized sampling and analysis of dust obtained after brushing the inside surfaces of dumpsters. In 50% of the specimens (10/20) we found mites belonging to the following families: Pyroglyphidae (Dermatophagoides spp.), Acaridae (Acarus siro) and a lower amount of Cheyletidae (Cheyletus spp.). An indirect test (guanine test) was also performed and gave positivity in 16 dust samples (80%). The insides of dumpsters showed to be an optimal environment for mites survival and reproduction because of cracks and grooves on the walls, the high humidity level and the presence of mould. These mites probably come from dwelling places and other environments (markets, slaughters-houses, farms, etc.). This suggests that mites allergens can be released during rubbish discharging from the dumpsters and represent a possible risk for the employees. 相似文献
38.
Andrea Abelmann 《Polar Biology》1992,12(3-4):357-372
Summary The study of radiolarians collected during sediment trap experiments in the Drake Passage, the northern Powell Basin, and the King George Basin of the Bransfield Strait provides new information on the fluxes of radiolarian shells in Antarctic waters, on the annual flux pattern, the species distribution and its ecological significance, and on alteration processes of the radiolarian shells in the water column and at the sediment/water interface. A 28-month monitoring with time-series sediment traps in the Bransfield Strait indicates an annual flux pattern characterized by short-term flux pulses during austral summer, which reach daily fluxes of up to 5 × 103 shells m–2 and which account for more than 90% of the total annual flux. The distinct seasonal variations are linked to variations in the sea ice coverage. Other controlling factors are the production of phytoplankton and the impact by zooplankton grazers, e.g., krill. During the summer flux pulses the vertical fluxes of radiolarians range between ca. 3 and 21 × 104 shells m–2, values that are one or more orders of magnitudes lower than fluxes observed at sites in the tropical and northern high-latitude ocean. Significant lateral transport of radiolarians was documented during the austral summer in the Bransfield Strait by a factor of 10 increase of the radiolarian flux in the lower portion of the water column and the species composition trapped in deeper waters. Radiolarian assemblages associated with pelagic and neritic environments characterized by typical Antarctic taxa (Antarctissa spp.) and a group of species with bipolar distribution (e.g. Plectacantha oikiskos, Phormacantha hystrix), respectively, are distinguished. While the signal of polycystine radiolarians is relatively well recorded in the sediments, the shells of phaeodarians, which were observed at fluxes of up to 1 × 103 shells m–2day–1 in the upper portion of the water column, are almost completely dissolved during settling through the water column. 相似文献
39.
Valeria Cavaliere Franco Graziani Silvia Andone Andrea Manzi Carla Malva 《Molecular & general genetics : MGG》1991,230(3):433-441
Summary The abnormal oocyte phenotype is characterized by instability, as shown by the loss and reappearance of the abo maternal effect under specific genetic conditions. Our previous finding that a correlation exists between the abo phenotype and the presence of a blood transposon in region 32E, led us to perform an extensive genetic and molecular analysis of the most significant aspects of the abo phenotype in different genetic backgrounds. The results of these experiments can be summarized as follows: Complete reversion occurs only when the blood transposon is lost, thus definitively demonstrating that the insertion of the blood transposon in region 32E is the molecular event that causes the pleiotropic abo phenotype. Partial reversion can also occur without loss of the transposon, indicating that different molecular pathways may be involved in the loss of the abo phenotype. Reappearance of the full abo phenotype can occur only in heterozygous lines constructed from partially revertant abo homozygous lines that have not lost the blood transposon. 相似文献
40.