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Sigrun Feldmann Georg A. Sprenger Hermann Sahm 《Applied microbiology and biotechnology》1989,31(2):152-157
Summary Grown anaerobically on d-xylose, Klebsiella planticola ATCC 33531 produced acetate, formate, lactate, CO2 and ethanol as major end-products. A Mu-insertion mutant which lacked pyruvate-formate-lyase showed among its fermentation products more than 70% d-lactate with residual acetate, 2,3-butanediol, and traces of ethanol, formate, and CO2. After the introduction of a plasmid carrying the gene for the enzyme pyruvate decarboxylase from Zymomonas mobilis, this Klebsiella mutant became an efficient ethanol producer. The recombinant strain produced 387 mM ethanol from 275 mM xylose in 80 h, about 83% of the theoretical maximal yield. Furthermore, this mutant consumed more than double the amount of xylose (41 g/l) compared to the wild-type, due to reduced production of inhibiting acids during growth.Dedicated to Professor Dr. Zähner on the occasion of his 60th birthday 相似文献
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The uterine acetylcholinesterase and total cholinesterase (acetylcholinesterase plus butyrylcholinesterase) activities in normal and fenchlorphos treated blue fox vixens were determined during various reproductive states. AChE and Total-ChE of non-medicated vixens in oestrus were about one half of those in anoestrus. In pregnant uteri (luteal phase) the activities were 25 % and 30% compared to anoestrus. In vixens given 100 mg/kg fenchlorphos for 3 weeks during anoestrus, the remaining activity of AChE in uterus were in average 37%. Pregnant and non-pregnant vixens in the luteal phase medicated prior to mating and during time of implantation, displayed AChE activities which were only moderabely reduced (remaining activities 83% and 72% compared to medicated animals in anoestrus: remaining activity 37%). Plasma ChE-activity increased during pregnancy in the controls while enzyme activity was strongly reduced in animals given 100 mg/kg fenchlorphos daily through the whole pregnancy. It was concluded that the previous reported embryotoxic effect of fenchlorphos in the blue fox did not seem to be directed towards the moderate inhibition of the uterine cholinesterases. 相似文献
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Sigrun Machemer-Röhnisch Richard Bräucker Hans Machemer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,171(6):779-790
Summary In the statocystoid-bearing, flat ciliate Loxodes, the peculiar steady locomotion on submersed substrates (called gliding) was investigated between 1 g and 5.4 g under controlled environmental conditions in a centrifuge microscope. Videorecordings of the movements of large cell populations were processed with an automated analysis procedure. At 1 g, possible sedimentation was fully compensated, and vertical shifts of the population were neutralized because upward and downward orientations of the cells occurred at equal proportions (neutral gravitaxis). With rising gravity the resultant velocity of upward-gliding cells remained unchanged, whereas the velocity of downward-gliding cells increased continuously. Long-term exposure to hypergravity did not generate detectable signs of adaptation. The bipolar orientation of Loxodes persisted even under fivefold normal gravity, but the axis of orientation rotated from the gravity axis in the counterclockwise direction. The data suggest that both gravikinesis and graviorientation of gliding Loxodes are instrumental in perfect neutralization of sedimentation at terrestrial conditions. 相似文献
6.
With regards to pollination there exist several mutualistic relationships between Hadena -species and Caryophyllaceae. As mutualists have both negative and positive effects on their partners, mutualism is often betoken as reciprocative exploitation which may shift to parasitism if the exploitation of one partner becomes prevalent.
Several Silene - and Saponaria -species are considered to be larval host plants of Hadena bicruris . Although Silene latifolia ssp. alba and S. dioica are frequently cited as hosts of the seed eating larvae, field and laboratory observations at Ulm were suggestive for only S. latifolia ssp. alba being a suitable host. Records of the oviposition behavior of H. bicruris made it evident that in fact a considerable number of eggs could be found in planted stands of both species. On the other hand, phenological data of the flowering periods and of the oviposition behavior of H. bicruris showed that S. latifolia ssp. alba is clearly preferred for oviposition if host selection is possible due to contemporaneous flowering of individuals of both plant species growing at close range. In addition, the flowering periods of S. latifolia ssp. alba and the periods of moth activity overlap to a large extent. This is not the case in S. dioica . Feeding experiences first indicated that the caterpillars may not prefer one of the species to the other, but comparison of the pupal weight of the animals reared on fruits of exclusively one of the species showed that the seeds of S. latifolia ssp. alba were more profitable for nutrition than those of S. dioica ; the pupal weight of animals reared on seeds of the former species significantly exceeded that of animals reared on seeds of the latter one. The question arises if the symbiosis of H. bicruris and its hosts constitutes a stable situation or if an evolutionary shift to mutualism or parasitism will take place. 相似文献
Several Silene - and Saponaria -species are considered to be larval host plants of Hadena bicruris . Although Silene latifolia ssp. alba and S. dioica are frequently cited as hosts of the seed eating larvae, field and laboratory observations at Ulm were suggestive for only S. latifolia ssp. alba being a suitable host. Records of the oviposition behavior of H. bicruris made it evident that in fact a considerable number of eggs could be found in planted stands of both species. On the other hand, phenological data of the flowering periods and of the oviposition behavior of H. bicruris showed that S. latifolia ssp. alba is clearly preferred for oviposition if host selection is possible due to contemporaneous flowering of individuals of both plant species growing at close range. In addition, the flowering periods of S. latifolia ssp. alba and the periods of moth activity overlap to a large extent. This is not the case in S. dioica . Feeding experiences first indicated that the caterpillars may not prefer one of the species to the other, but comparison of the pupal weight of the animals reared on fruits of exclusively one of the species showed that the seeds of S. latifolia ssp. alba were more profitable for nutrition than those of S. dioica ; the pupal weight of animals reared on seeds of the former species significantly exceeded that of animals reared on seeds of the latter one. The question arises if the symbiosis of H. bicruris and its hosts constitutes a stable situation or if an evolutionary shift to mutualism or parasitism will take place. 相似文献
7.
Sigrun Skjelseth Arne Moksnes Eivin Røskaft H. Lisle Gibbs Michael Taborsky Barbara Taborsky Marcel Honza Oddmund Kleven 《Journal of avian biology》2003,35(1):21-24
Microsatellite DNA markers were used to investigate parentage relationships in a population of common cuckoo Cuculus canorus . Thirty adults and 55 nestlings were genotyped at six loci from blood samples collected over a four-year period. To test whether each cuckoo female specialises in parasitising one single host species (Host Preference Hypothesis), the maternal relationships were used to record each female's host choice. The results supported the Host Preference Hypothesis since no female (N=3) was recorded to have parasitised more than one of four congeneric host species breeding in the area. In contrast, the males (N=4) did not show such specialisation since two of them sired offspring reared by different host species. 相似文献
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Developmental changes of nerve growth factor and its mRNA in the rat hippocampus: Comparison with choline acetyltransferase 总被引:4,自引:0,他引:4
Georg Auburger Rolf Heumann Rainer Hellweg Sigrun Korsching Hans Thoenen 《Developmental biology》1987,120(2):322-328
Previous experiments have demonstrated that in the septo-hippocampal system choline acetyltransferase (ChAT) is induced by nerve growth factor (NGF) (Gnahn et al. (1983) Dev. Brain Res. 9, 45-52) and that hippocampal NGF and mRNANGF levels are correlated with the density of cholinergic innervation (Korsching et al. (1985) EMBO J. 4, 1389-1393). In the present investigation we have compared the developmental changes of ChAT, NGF, and mRNANGF levels in this system. During the postnatal development of the hippocampus the time courses of NGF and ChAT were well correlated including the most rapid increase between P12 and P14. This increase in hippocampal NGF was preceded by a corresponding increase in mRNANGF. The developmental changes in hippocampal NGF levels were also closely reflected by corresponding changes in the septum. This, together with previous observations (Korsching et al., 1985) that the adult septum, in spite of relatively high NGF levels, does not contain measurable quantities of mRNANGF, suggests that the NGF levels in the septum are determined by the quantity of NGF transported retrogradely from the field of innervation rather than by local synthesis. During the prenatal period hippocampal NGF levels were relatively high, whereas the mRNANGF was below the level of detection. Since the ingrowth of septal fibers, and with that also the removal of NGF by retrograde transport, begins around birth, the relatively high prenatal NGF levels probably result from an accumulation produced by a small copy number of mRNANGF prior to the removal of NGF by retrograde axonal transport. It is concluded that the correlation of the developmental changes in NGF and mRNANGF with the ChAT activity in the hippocampus further supports the concept of a physiological role of NGF in the central nervous system. 相似文献
10.
Václav Brázda Jana Čechová Jan Coufal Sigrun Rumpel Eva B. Jagelská 《Journal of biomolecular structure & dynamics》2013,31(4):371-378
The 14-3-3 protein family is a highly conserved and widely distributed group of proteins consisting of multiple isoforms in eukaryotes. Ubiquitously expressed, 14-3-3 proteins play key roles in DNA replication, cell cycle regulation, and apoptosis. The function of 14-3-3 proteins is mediated by interaction with a large number of other proteins and with DNA. It has been demonstrated that 14-3-3γ protein binds strongly to cruciform structures and is crucial for initiating replication. In this study, we analyzed DNA binding properties of the 14-3-3γ isoform to linear and supercoiled DNA. We demonstrate that 14-3-3γ protein binds strongly to long DNA targets, as evidenced by electrophoretic mobility shift assay on agarose gels. Binding of 14-3-3γ to DNA target results in the appearance of blurry, retarded DNA bands. Competition experiments with linear and supercoiled DNA on magnetic beads show very strong preference for supercoiled DNA. We also show by confocal microscopy that 14-3-3 protein in the HCT-116 cell line is co-localized with DNA cruciforms. This implies a role for the 14-3-3γ protein in its binding to local DNA structures which are stabilized by DNA supercoiling. 相似文献