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991.
992.
The average height of 31-aged Robinia pseudoacacia plantation in west mountain of Beijing is 7 in and the mean breastheight diameter of tree is 8.3 cm. The number of tree per hectare appears 1750. The canopy coverage of plantation shows 0.5. Using tile diameter square at tree breast height times tree height (D2H), as an independing variable, to estimate the dry weight of various parts of trees, between them the significient correlations occur. According to the modle of Wstem=58.88(D2H)0.88 (WBranch)=e7.77+0.001(D2H) (Wleaf)=e5.71+0.0008(D2H) (Wroot)=e7.67+0.0009(D2H) 28.45 t/ha of the stem biomass, 11.6 t/ha of the branch biomass. 0.97 t/ha of the leaf biomass, 7.6 t/ha of the root biomass are estimated in arbor layer. The aboveground and belowground biomass of shrub and herb layers axe 13.71 t/ha and 10.72 t/ha respectively in September, the biomass of shrub and herb layer is 24.43 t/ha. 73.05 t/ha of the total biomass in Robinia pseudoacacia plantation is obtained. 相似文献
993.
湖北省三品种猪27个微卫星座位的遗传变异 总被引:41,自引:2,他引:41
采用国际动物遗传学会(ISAG)和联合国粮农组织(FAO)共同推荐的27个微卫星标记,对湖北省3个主要地方猪种(通城猪、清平猪和阳新猪)的遗传变异进行了检测。计算出各个品种的基因杂合度、各个座位的多态信息含量及品种间的遗传距离。结果表明,3个地方猪种的平均基因杂合度分别为0.7489、0.6987和0.6273,遗传多样性比较丰富;通城猪和清平猪亲缘关系较近,而两者与阳新猪亲缘关系略远。 相似文献
994.
995.
996.
Li YZ Pan YH Sun CB Dong HT Luo XL Wang ZQ Tang JL Chen B 《Plant molecular biology》2010,74(6):573-590
A cDNA library was constructed from the root tissues of cassava variety Huanan 124 at the root bulking stage. A total of 9,600
cDNA clones from the library were sequenced with single-pass from the 5′-terminus to establish a catalogue of expressed sequence
tags (ESTs). Assembly of the resulting EST sequences resulted in 2,878 putative unigenes. Blastn analysis showed that 62.6%
of the unigenes matched with known cassava ESTs and the rest had no ‘hits’ against the cassava database in the integrative
PlantGDB database. Blastx analysis showed that 1,715 (59.59%) of the unigenes matched with one or more GenBank protein entries
and 1,163 (40.41%) had no ‘hits’. A cDNA microarray with 2,878 unigenes was developed and used to analyze gene expression
profiling of Huanan 124 at key growth stages including seedling, formation of root system, root bulking, and starch maturity.
Array data analysis revealed that (1) the higher ratio of up-regulated ribosome-related genes was accompanied by a high ratio
of up-regulated ubiquitin, proteasome-related and protease genes in cassava roots; (2) starch formation and degradation simultaneously
occur at the early stages of root development but starch degradation is declined partially due to decrease in UDP-glucose
dehydrogenase activity with root maturity; (3) starch may also be synthesized in situ in roots; (4) starch synthesis, translocation,
and accumulation are also associated probably with signaling pathways that parallel Wnt, LAM, TCS and ErbB signaling pathways
in animals; (5) constitutive expression of stress-responsive genes may be due to the adaptation of cassava to harsh environments
during long-term evolution. 相似文献
997.
We investigated the effect of enhanced atmospheric ammonia (NH3) in combination with low and high nitrogen (LN and HN, respectively) growth medium on photosynthetic characteristics of two maize (Zea mays L.) cultivars (NE5 with high- and SD19 with low N-use efficiency) across long-term growth period and their diurnal change patterns exposed to 10 nl l−1 and 1,000 nl l−1 NH3 fumigation in open-top chambers (OTCs). Regardless of the level of N in medium, increased NH3 concentration promoted maximum net photosynthetic rate (P max) and apparent quantum yield (AQY) of both cultivars at earlier growth stages, but inhibited P max of NE5 from silking to maturity stage and that of SD19 at maturity stage only above the ambient concentration. Greater positive/less negative responses were predominant in the LN than in the HN treatment, especially for SD19. Dark respiration rate (R D) remained more enhanced in the LN than in the HN treatment for SD19 as well as increased in the LN while decreased in the HN treatment for NE5 at their silking stage, following exposure to elevated NH3 concentration. Additionally, enhanced atmospheric NH3 increased net photosynthetic rate (P N) and stomatal conductance (g s) but reduced intercellular CO2 concentration (C i) of both cultivars with either the LN or HN treatment during the diurnal period at tasseling stage. The diurnal change patterns of P N and g s showed bimodal curve type and those of C i presented single W-curve type for NE5, when NH3 concentration was enhanced. As for SD19, single-peak curve type was showed for both P N and g s while single V-curve type for C i. All results supported the hypothesis that appropriately enhanced atmospheric NH3 can increase assimilation of CO2 by improving photosynthesis of maize plant, especially at earlier growth stages and after photosynthetic “noon-break” point. These impacts of elevated NH3 concentration were more beneficial for SD19 as compared to those for NE5, especially in the LN supply environment. 相似文献
998.
Qi-Feng Wang Yue Zhao Qiong Yi Kun-Zhi Li Yong-Xiong Yu Li-Mei Chen 《Acta Physiologiae Plantarum》2010,32(6):1209-1220
Numerous studies with transgenic plants have demonstrated that overexpression of enzymes related to organic acid metabolism under the control of CaMV 35S promoter increased organic acid exudation and Al-resistance. The synthesis of organic acids requires a large carbon skeleton supply from leaf photosynthesis. Thus, we produced transgenic tobacco overexpressing cytosolic malate dehydrogenase (MDH) cDNA from Arabidopsis thaliana (amdh) and the MDH gene from Escherichia coli (emdh), respectively, under the control of a leaf-specific light-inducible promoter (Rubisco small subunit promoter, PrbcS) in the present study. Our data indicated that an increase (120–130%) in MDH-specific activity in leaves led to an increase in malate content in the transgenic tobacco leaves and roots as well as a significant increase in root malate exudation compared with the WT plants under the acidic (pH 4.5) conditions irrespective of 300 μM Al3+ stress absence or presence. After being exposed to 25 μM Al3+ in a hydroponic solution, the transgenic plants exhibited stronger Al-tolerance than WT plants and the degree of A1 tolerance in the transgenic plants corresponded with the amount of malate secretion. When grown in an Al-stress perlite medium, the transgenic tobacco lines showed better growth than the WT plants. The results suggested that overexpression of MDH driven by the PrbcS promoter in transgenic plant leaves enhanced malate synthesis and improved Al-resistance. 相似文献
999.
Inorganic nanoparticles (NPs) including semiconductor quantum dots (QDs), iron oxide NPs and gold NPs have been developed as contrast agents for diagnostics by molecular imaging. Compared with traditional contrast agents, NPs offer several advantages: their optical and magnetic properties can be tailored by engineering the composition, structure, size and shape; their surfaces can be modified with ligands to target specific biomarkers of disease; the contrast enhancement provided can be equivalent to millions of molecular counterparts; and they can be integrated with a combination of different functions for multimodal imaging. Here, we review recent advances in the development of contrast agents based on inorganic NPs for molecular imaging, and also touch on contrast enhancement, surface modification, tissue targeting, clearance and toxicity. As research efforts intensify, contrast agents based on inorganic NPs that are highly sensitive, target-specific and safe to use are expected to enter clinical applications in the near future. 相似文献
1000.
Shihong Zhang Yi Wei Huimei Yu Jinliang Liu Hongyu Pan 《Russian Journal of Plant Physiology》2010,57(5):670-675
Most monocotyledons like cereals accumulate antifreeze proteins in the apoplast during cold acclimation, but it is still uncertain
whether dicotyledons do. Here we report the isolation and characterisation of a 33-kD apoplastic chitinase extracted from
the corolla of wintersweet (Chinmonanthus praecox communis L.), which was purified using successive column chromatography on Phenyl-Sepharose, DEAE-Sepharose, and CM-Sepharose. Antifreezing
activity of chitinase was confirmed in terms of the formation of bipyramidal ice crystals and high thermal-hysteresis values.
Interestingly, chitinase was also found to affect germination of fungal spores of four major plant pathogens. From these data,
we hypothesize that, under natural conditions, wintersweet as one of the overwintering dicotyledons also accumulates apoplastic
antifreeze proteins like monocotyledons. To our knowledge, this is the first report on the isolation of dicotyledon apoplastic
chitinase with high-level antifreeze and antifungal activities. 相似文献