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801.
Abstract Starvation for different individual nutrients revealed various morphotypes of Vibrio sp. strain S14. Carbon or multiple-nutrient starved cells formed ultramicrocells with low respiratory activity and high culturability. In contrast, cells starved for nitrogen or phosphorus formed filaments or swollen rods with large inclusion bodies of PHB. These cells exhibited a 3–4 log decrease in culturability, nevertheless many were actively respiring and direct viable counts equalled at least 80% of the original number of cells. After 2–3 days of prolonged incubation, microcolonies appeared at approximately the same number of cells as at the onset of starvation. A nutrient-induced increase in respiratory activity, after 120 h of starvation, was instantaneous for cells starved for carbon or multiple-nutrients, but cells depleted of nitrogen or phosphorus exhibited a lag period of at least 3 h. 相似文献
802.
803.
Staffan Tamm 《Behavioural processes》1977,2(3):293-299
Social hierarchy was studied in two flocks (14 and 10 individuals, respectively) of captive jackdaws. Parent birds acquired high-ranking positions during the nesting period. Outside the breeding season the hierarchy seemed to be stable. Males generally dominated females. When the top-ranking male arrived at the feeding place it tended to supplant one of the feeding birds rather than choose an unoccupied site. 相似文献
804.
Anna K Jönsson Olav Spigset Micaela Tjäderborn Henrik Druid Staffan Hägg 《BMC clinical pharmacology》2009,9(1):7-5
Background
Pharmaceutical drug poisonings have previously been reported using single sources of information, either hospital data or forensic data, which might not reveal the true incidence. We therefore aimed to estimate the incidence of suspected fatal drug poisonings, defined as poisonings by pharmaceutical agents, by using all relevant case records from various sources in a Swedish population. 相似文献805.
Dryas octopetala has heliotropic flowers, whose petals reflect the light on the pistils, thus warming them up. The effects of this reflection on seed formation and development were studied by measuring the pistil temperature of intact flowers, of flowers with petals removed, of shaded flowers, and of flowers constrained in such a way as always to be directed towards the zenith. In August, the seeds of these flowers were collected, counted and weighed. The temperature differences between the differently treated flowers were greates about noon, the flowers ranking as follows in ascending order of temperature: shaded flowers, flowers without petals, constrained flowers and intact flowers. The mean temperature differences between the gynoecia and the air, in degrees Celsius, were: 1.1, 1.8, 2.5 and 3.2, respectively. The same ranking was obtained for the different treatments, when arranged in order of ascending weight per seed, except that the positions of the shaded flowers and the flowers without petals were interchanged. The mean values of the weight per seed in milligrams were: 0.42, 0.48, 0.53 and 0.61 for the groups flowers without petals, shaded flowers, constrained flowers and intact flowers, respectively. 相似文献
806.
807.
Mihaela Ilieva David P.L. Toews Staffan Bensch Christoffer Sjöholm Susanne Åkesson 《Behavioural processes》2012
Topography and historical range expansion has formed a so-called migratory divide between two subspecies of willow warbler (Phylloscopus trochilus) in central Scandinavia. The autumn migratory directions of individuals assigned molecularly to both subspecies and possible hybrids were recorded using orientation cage experiments in southwest and southeast Sweden. We found pronounced differences in willow warblers’ orientation in respect to genotype. The mean directions registered in the control experiments were in accordance with the ringing recoveries and analyses of stable isotopes for Scandinavian willow warblers. With the same individuals we performed displacement experiments between both sites. They resulted in non-significant orientation, which could be explained by the intermediate distance of the displacement or reactions to housing, transportation and location. On a separate set of birds we tested whether stress following transportation could explain the disorientation and found that orientation before and after transport was unchanged. Experimental studies of effects of intermediate displacements across longitudes and studies of orientation of hybrid individuals in the zones of migratory divides are crucial for understanding the mechanisms underlying orientation behaviour. Our work further stresses the importance of knowing the migration genotype of a particular bird under study, in order to correctly evaluate expected migration routes. 相似文献
808.
Samantha J Emery-Corbin Joshua J Hamey Brendan R E Ansell Balu Balan Swapnil Tichkule Andreas J Stroehlein Crystal Cooper Bernie V McInerney Soroor Hediyeh-Zadeh Daniel Vuong Andrew Crombie Ernest Lacey Melissa J Davis Marc R Wilkins Melanie Bahlo Staffan G Svrd Robin B Gasser Aaron R Jex 《Molecular biology and evolution》2020,37(12):3525
Methylation is a common posttranslational modification of arginine and lysine in eukaryotic proteins. Methylproteomes are best characterized for higher eukaryotes, where they are functionally expanded and evolved complex regulation. However, this is not the case for protist species evolved from the earliest eukaryotic lineages. Here, we integrated bioinformatic, proteomic, and drug-screening data sets to comprehensively explore the methylproteome of Giardia duodenalis—a deeply branching parasitic protist. We demonstrate that Giardia and related diplomonads lack arginine-methyltransferases and have remodeled conserved RGG/RG motifs targeted by these enzymes. We also provide experimental evidence for methylarginine absence in proteomes of Giardia but readily detect methyllysine. We bioinformatically infer 11 lysine-methyltransferases in Giardia, including highly diverged Su(var)3-9, Enhancer-of-zeste and Trithorax proteins with reduced domain architectures, and novel annotations demonstrating conserved methyllysine regulation of eukaryotic elongation factor 1 alpha. Using mass spectrometry, we identify more than 200 methyllysine sites in Giardia, including in species-specific gene families involved in cytoskeletal regulation, enriched in coiled-coil features. Finally, we use known methylation inhibitors to show that methylation plays key roles in replication and cyst formation in this parasite. This study highlights reduced methylation enzymes, sites, and functions early in eukaryote evolution, including absent methylarginine networks in the Diplomonadida. These results challenge the view that arginine methylation is eukaryote conserved and demonstrate that functional compensation of methylarginine was possible preceding expansion and diversification of these key networks in higher eukaryotes. 相似文献
809.
Propylthiouracil and thyroxine were given daily to rats for 4 weeks. Samples of colloid were collected in vivo from the superficial thyroid follicles during this period and their protein composition was analysed by gel electrophoresis.It was observed that the aggregates of thyroglobulin, i.e., the 27-S thyroid iodoprotein and the heavier fractions, were reduced to 50% after 1 week and were almost absent after 2 weeks.A faster migrating thyroglobulin fraction was observed in the samples of colloid and in the homogenate of the whole gland after 48 h of treatment. During the following period of treatment there was an increase in the relative amount of the faster migrating thyroglobulin fraction compared to 19-S thyroglobulin in the colloid, the former comprising approx. 75% of the globulins after 4 weeks, It can be concluded that propylthiouracil inhibits the formation of the 27-S iodoprotein and that a structurally altered and iodine-poor thyroglobulin fraction is accumulated in the follicle lumen. 相似文献
810.
Green fluorescent protein as a reporter system in the transformation of barley cultivars 总被引:5,自引:0,他引:5
Staffan Ahlandsberg P. Sathish Chuanxin Sun Christer Jansson 《Physiologia plantarum》1999,107(2):194-200
A cereal transformation vector, pN1473, containing the strong constitutive rice actin promoter Act-1 , a multiple cloning site, and the nos terminator, was constructed. Fusion of a plant-optimized gfp gene to Act-1 in pN1473 resulted in the vector pN1473GFP. To assess the suitability of pN1473, and GFP as a reporter system in barley transformation, two barley cultivars (Baronesse and Golden Promise) were transformed by microprojectile bombardment. Transient gfp expression in transformed embryogenic callus material was detectable by fluorescence microscopy less than 12 h after transformation. The presence of the gfp gene in callus and regenerated plantlets was confirmed by PCR amplification and DNA gel-blot analysis. 相似文献