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2.
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
3.
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
4.
Levels of nerve growth factor and its mRNA in the central nervous system of the rat correlate with cholinergic innervation. 总被引:49,自引:6,他引:43
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The levels of nerve growth factor (NGF) and its mRNA in the rat central nervous system were determined by two-site enzyme immunoassay and quantitative Northern blots, respectively. Relatively high NGF levels (0.4-1.4 ng NGF/g wet weight) were found both in the regions innervated by the magnocellular cholinergic neurons of the basal forebrain (hippocampus, olfactory bulb, neocortex) and in the regions containing the cell bodies of these neurons (septum, nucleus of the diagonal band of Broca, nucleus basalis of Meynert). Comparatively low, but significant NGF levels (0.07-0.21 ng NGF/g wet weight) were found in various other brain regions. mRNANGF was found in the hippocampus and cortex but not in the septum. This suggests that magnocellular cholinergic neurons of the basal forebrain are supplied with NGF via retrograde axonal transport from their fields of innervation. These results, taken together with those of previous studies showing that these neurons are responsive to NGF, support the concept that NGF acts as trophic factor for magnocellular cholinergic neurons. 相似文献
5.
6.
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
7.
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
8.
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
9.
Relationship between levels of nerve growth factor (NGF) and its messenger RNA in sympathetic ganglia and peripheral target tissues. 总被引:29,自引:6,他引:23
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We have developed a sensitive assay for the quantification of nerve growth factor mRNA (mRNANGF) in various tissues of the mouse using in vitro transcribed RNANGF. Probes of both polarities were used to determine the specificity of the hybridization signals obtained. Comparison of NGF levels with its mRNA revealed that both were correlated with the density of sympathetic innervation. Thus, vas deferens contained high levels of both NGF and mRNANGF, whereas skeletal muscle levels were barely detectable, indicating that in peripheral tissues NGF levels are primarily regulated by the quantity of mRNANGF and not by the rate of processing of NGF precursor to NGF. However, although superior cervical ganglia contained the highest levels of NGF, its mRNA was barely detectable. Thus, the high levels of NGF in sympathetic ganglia result from retrograde axonal transport rather than local synthesis. The quantity of NGF found in the submandibular glands of female animals was three orders of magnitude higher than expected from their mRNA levels. This observation is discussed in the context of the difference between the mechanism of storage and exocytosis of exocrine glands versus the constitutive release from other tissues. 相似文献