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951.
Josef Urban Kateřina Holušová Ladislav Menšík Jan Čermák Petr Kantor 《Trees - Structure and Function》2013,27(1):97-110
Research related to the allometric relationships of tree height and projected tree crown area to diameter at breast height was conducted to look at the biological suitability and timber production potential of Douglas fir under the conditions present in central Europe. The dependence of allometric relationships on soil nutrient conditions were described in forest stands of Douglas fir and Norway spruce. The studied sites were climatically similar but differed in soil nutrient availability. A significant difference was found in the allometric relationships of Norway spruce trees from the nutrient poor and nutrient rich site. In contrast to the Norway spruce, there was no significant effect of site fertility on allometric relationships for Douglas fir suggesting that its allocation patterns were less sensitive to site nutrient conditions. Stem growth increment, which was measured weekly during two consecutive seasons for both species, was related to the weather conditions and available soil moisture. Stem growth of Douglas fir began about 2 weeks earlier than in the Norway spruce at both sites. At the nutrient rich site, most of the stem growth of both species occurred at the beginning of the season, while growth at the other site was more evenly distributed throughout the season. Data obtained in this study will be useful for modeling stem growth and analysis of water use efficiency of these two tree species. 相似文献
952.
Simon Renny‐Byfield Ales Kovarik Laura J. Kelly Jiri Macas Petr Novak Mark W. Chase Richard A. Nichols Mahesh R. Pancholi Marie‐Angele Grandbastien Andrew R. Leitch 《The Plant journal : for cell and molecular biology》2013,74(5):829-839
Recent advances have highlighted the ubiquity of whole‐genome duplication (polyploidy) in angiosperms, although subsequent genome size change and diploidization (returning to a diploid‐like condition) are poorly understood. An excellent system to assess these processes is provided by Nicotiana section Repandae, which arose via allopolyploidy (approximately 5 million years ago) involving relatives of Nicotiana sylvestris and Nicotiana obtusifolia. Subsequent speciation in Repandae has resulted in allotetraploids with divergent genome sizes, including Nicotiana repanda and Nicotiana nudicaulis studied here, which have an estimated 23.6% genome expansion and 19.2% genome contraction from the early polyploid, respectively. Graph‐based clustering of next‐generation sequence data enabled assessment of the global genome composition of these allotetraploids and their diploid progenitors. Unexpectedly, in both allotetraploids, over 85% of sequence clusters (repetitive DNA families) had a lower abundance than predicted from their diploid relatives; a trend seen particularly in low‐copy repeats. The loss of high‐copy sequences predominantly accounts for the genome downsizing in N. nudicaulis. In contrast, N. repanda shows expansion of clusters already inherited in high copy number (mostly chromovirus‐like Ty3/Gypsy retroelements and some low‐complexity sequences), leading to much of the genome upsizing predicted. We suggest that the differential dynamics of low‐ and high‐copy sequences reveal two genomic processes that occur subsequent to allopolyploidy. The loss of low‐copy sequences, common to both allopolyploids, may reflect genome diploidization, a process that also involves loss of duplicate copies of genes and upstream regulators. In contrast, genome size divergence between allopolyploids is manifested through differential accumulation and/or deletion of high‐copy‐number sequences. 相似文献
953.
Yongming Du Gefei Liu Yinxia Yan Dongyang Huang Wenhong Luo Marketa Martinkova Petr Man Toru Shimizu 《Biometals》2013,26(5):839-852
The heme-based oxygen-sensor phosphodiesterase from Escherichia coli (Ec DOS), is composed of an N-terminal heme-bound oxygen sensing domain and a C-terminal catalytic domain. Oxygen (O2) binding to the heme Fe(II) complex in Ec DOS substantially enhances catalysis. Addition of hydrogen sulfide (H2S) to the heme Fe(III) complex in Ec DOS also remarkably stimulates catalysis in part due to the heme Fe(III)–SH and heme Fe(II)–O2 complexes formed by H2S. In this study, we examined the roles of the heme distal amino acids, M95 (the axial ligand of the heme Fe(II) complex) and R97 (the O2 binding site in the heme Fe(II)–O2 complex) of the isolated heme-binding domain of Ec DOS (Ec DOS-PAS) in the binding of H2S under aerobic conditions. Interestingly, R97A and R97I mutant proteins formed an oxygen-incorporated modified heme, verdoheme, following addition of H2S combined with H2O2 generated by the reactions. Time-dependent mass spectroscopic data corroborated the findings. In contrast, H2S did not interact with the heme Fe(III) complex of M95H and R97E mutants. Thus, M95 and/or R97 on the heme distal side in Ec DOS-PAS significantly contribute to the interaction of H2S with the Fe(III) heme complex and also to the modification of the heme Fe(III) complex with reactive oxygen species. Importantly, mutations of the O2 binding site of the heme protein converted its function from oxygen sensor to that of a heme oxygenase. This study establishes the novel role of H2S in modifying the heme iron complex to form verdoheme with the aid of reactive oxygen species. 相似文献
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955.
Petr Pyek Jan uda Petr milauer Hana Sklov Zuzana Chumov Carla Lambertini Magdalena Lu
anov Hana Ryav Pavel Trvní
ek Kristýna emberov Laura A. Meyerson 《Ecology and evolution》2020,10(3):1106-1118
Among the traits whose relevance for plant invasions has recently been suggested are genome size (the amount of nuclear DNA) and ploidy level. So far, research on the role of genome size in invasiveness has been mostly based on indirect evidence by comparing species with different genome sizes, but how karyological traits influence competition at the intraspecific level remains unknown. We addressed these questions in a common‐garden experiment evaluating the outcome of direct intraspecific competition among 20 populations of Phragmites australis, represented by clones collected in North America and Europe, and differing in their status (native and invasive), genome size (small and large), and ploidy levels (tetraploid, hexaploid, or octoploid). Each clone was planted in competition with one of the others in all possible combinations with three replicates in 45‐L pots. Upon harvest, the identity of 21 shoots sampled per pot was revealed by flow cytometry and DNA analysis. Differences in performance were examined using relative proportions of shoots of each clone, ratios of their aboveground biomass, and relative yield total (RYT). The performance of the clones in competition primarily depended on the clone status (native vs. invasive). Measured in terms of shoot number or aboveground biomass, the strongest signal observed was that North American native clones always lost in competition to the other two groups. In addition, North American native clones were suppressed by European natives to a similar degree as by North American invasives. North American invasive clones had the largest average shoot biomass, but only by a limited, nonsignificant difference due to genome size. There was no effect of ploidy on competition. Since the North American invaders of European origin are able to outcompete the native North American clones, we suggest that their high competitiveness acts as an important driver in the early stages of their invasion. 相似文献
956.
Marcel Honza Petr Procházka Klára Morongová Miroslav Čapek Václav Jelínek 《Ethology : formerly Zeitschrift fur Tierpsychologie》2011,117(6):539-546
Discrimination of foreign eggs is one of the most studied aspects of host defences against avian brood parasites. Although many factors affecting host egg‐recognition processes have already been evaluated, only a few attempts have been made to test the importance of light conditions in microhabitats of host nests. Here, we examined whether the objectively measured nest light environment affects great reed warbler (Acrocephalus arundinaceus) responses towards real common cuckoo (Cuculus canorus) eggs. More specifically, we predicted that parasitic eggs will be rejected with a lower frequency from nests placed in darker conditions than those in lighter conditions. However, we found no effect of the ambient light on egg‐rejection behaviour alone, but the photosynthetically active radiation exhibited a positive interactive effect with chromatic contrast between cuckoo and host eggs. Most rejection events were accomplished when cuckoo eggs of poor mimicry were laid in well‐lit nests. Our study suggests that this phenomenon may have important implications for the evolution of egg mimicry and host egg discrimination. We encourage further testing of the light environment hypothesis in other host species breeding in variable nest microhabitats and light conditions. 相似文献
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