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121.
122.
The multifunctional trans-activator Tat is an essential regulatory protein for HIV-1 replication and is characterized by high sequence diversity. Numerous experimental studies have examined Tat in HIV-1 subtype B, but research on subtype C Tat is lacking, despite the high prevalence of infections caused by subtype C worldwide. We hypothesized that amino acid differences contribute to functional differences among Tat proteins. In the present study, we found that subtype B NL4-3Tat and subtype C isolate HIV1084 i Tat exhibited differences in stability by overexpressing the fusion protein Tat-Flag. In addition, 1084 i Tat can activate LTR and NF-κB more efficiently than NL4-3 Tat. In analyses of the activities of the truncated forms of Tat, we found that the carboxylterminal region of Tat regulates its stability and transactivity. According to our results, we speculated that the differences in stability between B-Tat and C-Tat result in differences in transactivation ability. 相似文献
123.
黄土丘陵区小流域土地利用对土壤有机碳和全氮的影响 总被引:14,自引:0,他引:14
通过野外调查和室内分析,研究了黄土丘陵沟壑区燕沟流域农地、果园、林地和草地0~20cm表层土壤的有机碳(SOC)和全氮(TSN)积累特征.结果表明:该区SOC含量平均值为7·56g·kg-1,TSN平均值为0·71g·kg-1.其中,农地SOC和TSN平均值分别为4·67和0·48g·kg-1,且梯田较低,川坝地较高.与农地相比,果园SOC(4·33g·kg-1)和TSN(0·46g·kg-1)平均值略有降低,草地较高.林地SOC和TSN平均值较农地高117·7%和89·4%.该区SOC和TSN含量的变异系数为69·7%和58·4%,以林地最大(62·8%和54·5%),草地和农地次之,果园最小(18·0%和22·9%).土壤C/N依果园、农地、草地和林地的顺序递增.该区各类土地利用方式下的SOC和TSN都呈极显著正相关(r=0·9791).黄土丘陵沟壑区基本农田建设和果园建设对SOC和TSN积累作用不明显;退耕还林还草、封山育林等土地利用优化措施明显促进了SOC和TSN的积累. 相似文献
124.
Comparison of APRI and Hydrus-2D models to simulate soil water dynamics in a vineyard under alternate partial root zone drip irrigation 总被引:2,自引:0,他引:2
Alternate partial root zone irrigation (APRI) is a new water-saving irrigation technique. It can reduce irrigation water and
transpiration without reduction in crop yield, thus increase water and nutrient use efficiency. Understanding of soil moisture
distribution and dynamic under the alternate partial root zone drip irrigation (APDI) can help to develop the efficient irrigation
schemes. In this paper, a two-dimensional (2D) root water uptake model was proposed based on soil water dynamic and root distribution
of grape vine, and a function of soil evaporation related to soil water content was defined under the APDI. Then the soil
water dynamic model of APDI (APRI-model) was developed based on the 2D root water uptake model and soil evaporation function
combined with average measured soil moisture content at 0–10 cm soil layer. Soil water dynamic in APDI was respectively simulated
by Hydrus-2D model and APRI-model. The simulated soil water contents by two models were compared with the measured value.
The results showed that the values of root-mean-square-error (RMSE) range from 0.01 to 0.022 cm3/cm3 for APRI-model, and from 0.012 to 0.031 cm3/cm3 for Hydrus-2D model. The average relative error between the simulated and measured soil water content is about 10% for APRI-model,
and from 11% to 29% for Hydrus-2D model, indicating that two models perform well in simulating soil moisture dynamic under
the APDI, but the APRI-model is more suitable for modeling the soil water dynamic in the arid region with greater soil evaporation
and uneven root distribution. 相似文献
125.
Enrichment of a common wheat genetic map and QTL mapping for fatty acid content in grain 总被引:2,自引:0,他引:2
Ying-ying Wang Xian-yin Sun Yan Zhao Fan-mei Kong Ying Guo Gui-zhi Zhang Yan-yan Pu Ke WuSi-shen Li 《Plant science》2011,181(1):65-75
DArT and SSR markers were used to saturate and improve a previous genetic map of RILs derived from the cross Chuan35050 × Shannong483. The new map comprised 719 loci, 561 of which were located on specific chromosomes, giving a total map length of 4008.4 cM; the rest 158 loci were mapped to the most likely intervals. The average chromosome length was 190.9 cM and the marker density was 7.15 cM per marker interval. Among the 719 loci, the majority of marker loci were DArTs (361); the rest included 170 SSRs, 100 EST-SSRs, and 88 other molecular and biochemical loci. QTL mapping for fatty acid content in wheat grain was conducted in this study. Forty QTLs were detected in different environments, with single QTL explaining 3.6-58.1% of the phenotypic variations. These QTLs were distributed on 16 chromosomes. Twenty-two QTLs showed positive additive effects, with Chuan35050 increasing the QTL effects, whereas 18 QTLs were negative with increasing effects from Shannong483. Six sets of co-located QTLs for different traits occurred on chromosomes 1B, 1D, 2D, 5D, and 6B. 相似文献
126.
D. Przybyl E. Fritzsche K. Edwards H. Kössel H. Falk J. A. Thompson G. Link 《Plant molecular biology》1984,3(3):147-158
Summary The genes coding for rRNAs from mustard chloroplasts were mapped within the inverted repeat regions of intact ctDNA and on ctDNA fragments cloned in pBR322. R-loop analysis and restriction endonuclease mapping show that the genes for 16S rRNA map at distances of 17 kb from the junctions of the repeat regions with the large unique region. The genes for 23S rRNA are located at distances of 2.8 kb from the junctions with the small unique region. Genes for 4.5S and 5S rRNA are located in close proximity to the 23S rRNA genes towards the small unique region. DNA sequencing of portions of the 5 terminal third from the mustard 16S rRNA gene shows 96–99% homology with the corresponding regions of the maize, tobacco and spinach chloroplast genes. Sequencing of the region proximal to the 16S rRNA gene reveals the presence of a tRNAVal gene in nearly the same position and with identical sequence as in maize, tobacco and spinach. Somewhat less but still strong homology is also observed for the tDNA Val/16S rDNA intercistronic regions and for the regions upstream of the tRNAVal gene. However, due to many small and also a few larger deletions and insertions in the leader region, common reading frames coding for homologous peptides larger than 44 amino acids can not be detected; it is therefore unlikely that this region contains a protein coding gene. 相似文献
127.
The planthopper genus Neodurium Fennah is reviewed and Neodurium
fennahi Chang & Chen, sp. n. (Hemiptera: Fulgoromorpha: Issidae) from China (Yunnan), is described and illustrated. A checklist of the species of Neodurium is given and a key provided for their separation. The female genitalia of Neodurium species are described for the first time. 相似文献
128.
129.
黄土沟壑区狼牙刺群落优势种群生态位研究 总被引:11,自引:3,他引:11
运用Levin公式和百分率相似公式,对狼牙刺群落中13个优势种群的生态位宽度、生态位相似性比例及其生态位重叠值进行了研究.结果表明,生态位宽度依次为狼牙刺(0.964)、茭蒿(0.77)、铁杆蒿(0.664)、黄背草(0.08)、远志(0.48)、狗尾草(0.472)、狗牙根(0.399)、白羊草(0.393)、达乌里胡枝子(0.327)、长芒草(0.321)、杠柳(0.292)、灌木铁线莲(0.21)、糙隐子草(0.234).狼牙刺与其他种群的生态位相似比在0.21~0.76之间,生态位重叠值较高,其他种群与狼牙刺之间的重叠值较低,表明狼牙刺与其他种群之间对资源的竞争并不十分激烈,因而能成为黄土沟壑区狼牙刺群落中利用资源能力和生态适应性最强的优势种群,并在维持群落的物种多样性和相对稳定性中发挥重要作用. 相似文献
130.
不同干扰对黄土区典型草原物种多样性和生物量的影响 总被引:3,自引:0,他引:3
对黄土区典型草原进行封育+施肥(EF)、封育+火烧(EB)、封育(E)和放牧(G)处理,实地调查分析群落盖度、高度、密度、地上现存量和物种多样性,以研究不同干扰对黄土区典型草原群落物种多样性和生物量的影响.结果表明:在4种干扰类型中,施肥+封育草地群落盖度和地上生物量最高,且优势度指数最高,这与禾本科草占优势地位有关,群落均匀度指数和多样性指数最低,符合“生态位理论”;放牧地群落高度、盖度、密度和地上现存量最低,群落丰富度指数和多样性指数最高,支持“中度干扰理论”;封育地密度和均匀度指数最高;具体表现为:4种干扰类型地上生物量的变化趋势为封育+施肥>封育+火烧>封育>放牧;说明长时间的封育对草地是一种严重干扰.群落丰富度指数(R和Ma)的排列顺序为放牧>封育+施肥>封育+火烧>封育,群落物种多样性指数(H'和D)的排列顺序为放牧>封育>封育+火烧>封育+施肥,优势度指数与多样性指数相反,群落均匀度指数(Jsw和Ea)的排列顺序为封育>放牧>封育+火烧>封育+施肥.不同干扰样地群落生产力与Shannon-Wiener和Simpson 多样性指数间呈负相关关系,这个结论可以用地上/地下竞争的相互作用来解释. 相似文献