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41.
The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat. 相似文献
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High and dry: post‐fire tree seedling establishment in subalpine forests decreases with post‐fire drought and large stand‐replacing burn patches 下载免费PDF全文
Brian J. Harvey Daniel C. Donato Monica G. Turner 《Global Ecology and Biogeography》2016,25(6):655-669
Aim Climate warming and increased wildfire activity are hypothesized to catalyse biogeographical shifts, reducing the resilience of fire‐prone forests world‐wide. Two key mechanisms underpinning hypotheses are: (1) reduced seed availability in large stand‐replacing burn patches, and (2) reduced seedling establishment/survival after post‐fire drought. We tested for regional evidence consistent with these mechanisms in an extensive fire‐prone forest biome by assessing post‐fire tree seedling establishment, a key indicator of forest resilience. Location Subalpine forests, US Rocky Mountains. Methods We analysed post‐fire tree seedling establishment from 184 field plots where stand‐replacing forest fires were followed by varying post‐fire climate conditions. Generalized linear mixed models tested how establishment rates varied with post‐fire drought severity and distance to seed source (among other relevant factors) for tree species with contrasting post‐fire regeneration adaptations. Results Total post‐fire tree seedling establishment (all species combined) declined sharply with greater post‐fire drought severity and with greater distance to seed sources (i.e. the interior of burn patches). Effects varied among key species groups. For conifers that dominate present‐day subalpine forests (Picea engelmannii, Abies lasiocarpa), post‐fire seedling establishment declined sharply with both factors. One exception was serotinous Pinus contorta, which did not vary with either factor. For montane species expected to move upslope under future climate change (Larix occidentalis, Pseudotsuga menziesii, Populus tremuloides) and upper treeline species (Pinus albicaulis), establishment was unrelated to either factor. Greater post‐fire tree seedling establishment on cooler/wetter aspects suggested local topographic refugia during post‐fire droughts. Main conclusions If future drought and wildfire patterns manifest as expected, post‐fire tree seedling establishment of species that currently characterize subalpine forests could be substantially reduced. Compensatory increases from lower montane and upper treeline species may partially offset these reductions, but our data suggest important near‐ to mid‐term shifts in the composition and structure of high‐elevation forests under continued climate warming and increased wildfire activity. 相似文献
44.
Activation of retrotransposon is a pivotal factor in the genesis of genetic polymorphism. Retrotransposon-based molecular markers are excellent tools for detecting genetic diversity and genomic changes associated with their activity. The objective of this study was to use IRAP markers to detect integration events of retrotransposon in Opuntia, and to compare IRAP and ISSR polymorphisms. To achieve these aims, five IRAP and five ISSR markers were analyzed on three varieties and their progenies. All IRAP primers showed an increase in the percentage of polymorphism, number of total bands, and polymorphic bands in the seedlings compared to their mother plants; that is, the offspring showed 13, 24 and 27 more bands than the mother plants from Tobarito, Montesa and Copena varieties, respectively. Conversely, sexual reproduction did not proportionally affect the variation in the number of ISSR bands, and neither did polymorphisms between mother plants and their offspring. Cluster and multivariate analyses based on IRAP and ISSR data revealed a clear separation between varieties, and there was no overlapping between seedlings of different varieties. The activation of retrotransposons in seedlings of opuntia with variable frequencies was evidenced. The presence of insertion and active retrotransposons may help to undertake studies on genetic diversity and evolution of Opuntia. 相似文献
46.
将水培后盆栽的花生幼苗,置于培养箱42℃高温培养,定时测定幼苗叶光合速率、叶绿素含量和叶绿体Ca2 -ATPase、Mg2 -ATPase的相对活性,并观察幼叶细胞内Ca2 分布的变化。试验结果表明:高温胁迫过程中,光合速率及叶绿素含量都随处理时间的延伸而下降,并呈显著正相关;叶绿体Ca2 -ATPase和Mg2 -ATPase高温胁迫过程中相对活性呈先升后降趋势,Ca2 -ATPase热敏性高于Mg2 -ATPase;高温胁迫过程中,Ca2 具有从胞外转运到胞质内和叶绿体中的趋势,Ca2 能够稳定高温胁迫下叶肉细胞膜和叶绿体的超微结构。 相似文献
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Growth, metabolic profiling and enzymes activities of Catharanthus roseus seedlings treated with plant growth regulators 总被引:1,自引:0,他引:1
The effect of different growth regulators on growth and the production of terpenoid indole alkaloids as well as some enzymes involved in the biosynthesis were studied in Catharanthus roseus seedlings. The seedlings were grown on MS solid medium containing different concentrations of each growth regulator for a period of one month. Extracted alkaloids were analyzed by HPLC for determination of terpenoid indole alkaloid quantities. Continuous availability of growth regulators induced different alkaloids with variable effects among the regulators. Gibberellic acid at concentration of either 5.8 M or 11.6 M resulted in elongation of shoots with lowering the number of leaves. Abscisic acid has a retardant effect on growth. Ethylene did not effect the growth pattern at concentration of 100 M but seedlings were not tolerant to higher concentrations. Methyljasmonate reduced the growth of the root system. Methyljasmonate was a general inducer for all alkaloids and increased the activity of strictosidine glucosidase. Ethylene applications promoted the pathways towards ajmalicine, serpentine, tabersonine and vindoline. Similar effect as for ethylene was observed for abscisic acid. Salicylic acid treatment increased the production of serpentine, tabersonine and higher concentration of salicylic acid induced vindoline accumulation. Peroxidase activity was also induced by salicylic acid. Gibberellic acid has little effect on alkaloid levels. 相似文献
49.
昆明地区香石竹病毒病流行状况调查及脱病毒苗的制备 总被引:3,自引:0,他引:3
对昆明地区3种不同生产模式下的香石竹(Dianthus caryophyllus L.)进行了调查,采集样本146号,利用酶联免疫法和电镜检测法对样本感染香石竹病毒的情况进行检测,结果表明昆明地区主要流行的香石竹为香石竹斑驳病毒和香石竹坏死斑点病毒,以带香石竹斑驳病毒的香石竹品种“俏新朗”为实验材料,研究了直接剥茎尖法,高温处理结合剥茎尖法和病毒痤处理结合剥茎尖法3种方法在脱病毒效率和茎尖成苗率的差异,实验结果表明以加热处理结合剥茎尖法脱病毒效果最好,0.2mm茎尖脱病毒率可达77.78%,加5%病毒座处理对脱病毒有一定的影响,直接剥茎尖法脱病毒效果最差。 相似文献
50.
Spleen cells of mice immunized with cis, trans (±) abscisic acid (ABA) conjugated to bovine serum albumin (BSA) were fused with myeloma cells to produce hybridomas. Hybridomas secreting antibodies to cis, trans (+) ABA were detected by enzyme-linked immunoassay and injected into the peritoneal cavity of mice to produce ascites fluid. Antibodies purified by size-exclusion chromatography were linked to cyanogen bromide-activated Sepharose beads and used to prepare immunoaffinity columns (IAC). Semi-purified conifer seedling (Douglas-fir [ Pseudotsuga menziesii (Mirb) Franco] lodgepole pine ( Pinus contorta Dougl), cedar ( Thuja plicata D. Don), and spruce [ Picea glauca (Moench) Voss)]) extracts were passed through IAC, washed thoroughly with water and then eluted with methanol. ABA in the methanol eluate was analysed by high performance liquid chromatography with UV detection. UV absorption of extracts before and after purification through IAC indicated an excellent purification of extract by IAC. The identity of the ABA peak was confirmed by gas chromatography-mass spectrometry. 相似文献