侯运高速公路上边坡绿化方案

高速公路上边坡由于适宜绿色植物生长发育的环境生态条件和其它绿化地面相比,立地条件更差、绿化难度更大、绿化效果更难保证,为了给高速公路上边坡成功绿化提供理论实践依据、技术支持,本文对侯运高速公路绿化绿化栽植地条件、栽植方法、苗木成活关键问题进行了讨论,结果表明:营养载体栽植是最好的绿化栽植方法,它较好解决了、苗木成活、土壤养分储存、土壤水分储存、苗木生长发育所需生态环境条件问题;建议主要的绿化树种应采用柠条、沙地柏、酸枣、油松、侧柏、四刺槟栗;高速公路上边坡用营养钵小苗,较宽阔地带用大树苗;绿化苗木栽植成功的关键问题在于维持苗木体内水分平衡。     

Crossing the nuclear envelope: hierarchical regulation of nucleocytoplasmic transport

Transport of macromolecules between the nucleus and cytoplasm is a critical cellular process for eukaryotes, and the machinery that mediates nucleocytoplasmic exchange is subject to multiple levels of control. Regulation is achieved by modulating the expression or function of single cargoes, transport receptors, or the transport channel. Each of these mechanisms has increasingly broad impacts on transport patterns and capacity, and this hierarchy of control directly affects gene expression, signal transduction, development, and disease.     

Blurring the boundary: the nuclear envelope extends its reach

The past decade has seen a complete rethinking of the traditional view of the nuclear envelope as simply a passive enclosure for the chromosomes. The convergence of several lines of clinical and basic research has revealed additional roles in both signaling and mitotic progression. It is becoming apparent that the nuclear envelope defines not only nuclear organization but also that of the cytoskeleton and, in this way, integrates both nuclear and cytoplasmic architecture.     

马里亚纳海沟东西两侧海域中尺度涡的海面高度计观测研究

使用2001—2006年的卫星海面高度计数据,对马里亚纳海沟东西两侧(15°～25°N,120°～160°E)海域中尺度涡的传播特性及其强度变化进行了研究。结果表明:在马里亚纳海沟以东形成的很多涡旋,都具有明显的西向传播特性,传播速度与第一斜压模式的Rossby长波的传播速度基本一致;反气旋式涡旋(暖涡)的面积大于气旋式涡旋(冷涡)的面积,并且呈现面积交替变化的特征,即冷涡面积大时暖涡面积小,反之亦然;以海面高度距平均方根值为指标的中尺度涡强度呈春夏季大、秋冬季小的季节性变化,但2004年出现了相反的现象;夏季和秋季,台湾岛和菲律宾群岛东侧的水深与中尺度涡的强度分布有着较好的对应关系,水深越大,强度也越大。     

马里亚纳海沟东西两侧海域中尺度涡的海面高度计观测研究

使用2001—2006年的卫星海面高度计数据,对马里亚纳海沟东西两侧(15°～25°N,120°～160°E)海域中尺度涡的传播特性及其强度变化进行了研究。结果表明:在马里亚纳海沟以东形成的很多涡旋,都具有明显的西向传播特性,传播速度与第一斜压模式的Rossby长波的传播速度基本一致;反气旋式涡旋(暖涡)的面积大于气旋式涡旋(冷涡)的面积,并且呈现面积交替变化的特征,即冷涡面积大时暖涡面积小,反之亦然;以海面高度距平均方根值为指标的中尺度涡强度呈春夏季大、秋冬季小的季节性变化,但2004年出现了相反的现象;夏季和秋季,台湾岛和菲律宾群岛东侧的水深与中尺度涡的强度分布有着较好的对应关系,水深越大,强度也越大。     

Plant Chimeras Used to Establish de novo Origin of Shoots

When African violet leaf explants are cultured in vitro, buds and shoots develop directly from the upper leaf surfaces. Three developmentally different African violet chimeras were cultured, and in each case adventitious shoots that developed into plants had the parent chimera pattern. A multicellular origin of the adventitious buds accounts for these results.     

Strong association of de novo copy number mutations with autism

We tested the hypothesis that de novo copy number variation (CNV) is associated with autism spectrum disorders (ASDs). We performed comparative genomic hybridization (CGH) on the genomic DNA of patients and unaffected subjects to detect copy number variants not present in their respective parents. Candidate genomic regions were validated by higher-resolution CGH, paternity testing, cytogenetics, fluorescence in situ hybridization, and microsatellite genotyping. Confirmed de novo CNVs were significantly associated with autism (P = 0.0005). Such CNVs were identified in 12 out of 118 (10%) of patients with sporadic autism, in 2 out of 77 (3%) of patients with an affected first-degree relative, and in 2 out of 196 (1%) of controls. Most de novo CNVs were smaller than microscopic resolution. Affected genomic regions were highly heterogeneous and included mutations of single genes. These findings establish de novo germline mutation as a more significant risk factor for ASD than previously recognized.     

Role of the glutathione redox cycle in acquired and de novo multidrug resistance

Drug resistance represents a major obstacle to successful cancer chemotherapy. However, the specific biochemical mechanisms responsible for clinical drug resistance are unknown. In these studies resistance to the antitumor agent adriamycin was found to involve two mechanisms, one that decreased drug accumulation by the P170 mechanism and another that altered the glutathione redox cycle, an important pathway in the detoxification of reactive oxygen. This dual mechanism of drug resistance was demonstrated in cell lines that had acquired the multidrug-resistant phenotype and in human colorectal cancer cells with de novo resistance. These studies support a model of acquired and de novo multidrug resistance that includes alterations in both drug accumulation and the glutathione redox cycle.     

Reversible compartmentalization of de novo purine biosynthetic complexes in living cells

Purines are synthesized de novo in 10 chemical steps that are catalyzed by six enzymes in eukaryotes. Studies in vitro have provided little evidence of anticipated protein-protein interactions that would enable substrate channeling and regulation of the metabolic flux. We applied fluorescence microscopy to HeLa cells and discovered that all six enzymes colocalize to form clusters in the cellular cytoplasm. The association and dissociation of these enzyme clusters can be regulated dynamically, by either changing the purine levels of or adding exogenous agents to the culture media. Collectively, the data provide strong evidence for the formation of a multi-enzyme complex, the "purinosome," to carry out de novo purine biosynthesis in cells.     

Nuclear winter: global consequences of multple nuclear explosions

The potential global atmospheric and climatic consequences of nuclear war are investigated using models previously developed to study the effects of volcanic eruptions. Although the results are necessarily imprecise due to wide range of possible scenaros and uncertainty in physical parameters, the most probable first-order effects are serious. Significant hemispherical attenuation of the solar radiation flux and subfreezing land temperatures may be caused by fine dust raised in high-yield nuclear surface bursts and by smoke from city and forest fires ignited by airbursts of all yields. For many simulated exchanges of several thousand megatons, in which dust and smoke are generated and encircle the earth within 1 to 2 weeks, average light levels can be reduced to a few percent of ambient and land temperatures can reach -15 degrees to -25 degrees C. The yield threshold for major optical and climatic consequences may be very low: only about 100 megatons detonated over major urban centers can create average hemispheric smoke optical depths greater than 2 for weeks and, even in summer, subfreezing land temperatures for months. In a 5000-megaton war, at northern mid-latitude sites remote from targets, radioactive fallout on time scales of days to weeks can lead to chronic mean doses of up to 50 rads from external whole-body gamma-ray exposure, with a likely equal or greater internal dose from biologically active radionuclides. Large horizontal and vertical temperature gradients caused by absorption of sunlight in smoke and dust clouds may greatly accelerate transport of particles and radioactivity from the Northern Hemisphere to the Southern Hemisphere. When combined with the prompt destruction from nuclear blast, fires, and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion, long-term exposure to cold, dark, and radioactivity could pose a serious threat to human survivors and to other species.     

Role of delayed nuclear envelope breakdown and mitosis in Wolbachia-induced cytoplasmic incompatibility

The bacterium Wolbachia manipulates reproduction in millions of insects worldwide; the most common effect is cytoplasmic incompatibility (CI). We found that CI resulted from delayed nuclear envelope breakdown of the male pronucleus in Nasonia vitripennis. This caused asynchrony between the male and female pronuclei and, ultimately, loss of paternal chromosomes at the first mitosis. When Wolbachia were present in the egg, synchrony was restored, which explains suppression of CI in these crosses. These results suggest that Wolbachia target cell cycle regulatory proteins. A striking consequence of CI is that it alters the normal pattern of reciprocal centrosome inheritance in Nasonia.