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排序方式: 共有98条查询结果,搜索用时 468 毫秒
1.
叶?在我国原记载2种,作者查看了采自江南7省区的标本30多件。共鉴定为8种,加上原有纪录的一未见种,我国总计9种,其中包括5新种和2种我国新纪录,本文主要记述4新种,属于丽叶?亚属的一新种已另文发表;并编制了我国产叶?的种检索表。 叶?多分布在雨量充沛地区,特别是热带岛屿,而本文中的泛叶?却采自远离海岸1200多km的贵州北部,以及藏叶?乃发现于北纬 29.2°的西藏墨脱,这对世界有关分类区系的研究,提供了新的资料。  相似文献   
2.
The plant defense hormone salicylic acid (SA) is perceived by two classes of receptors, NPR1 and NPR3/NPR4. They function in two parallel pathways to regulate SA-induced defense gene expression. To better understand the roles of the SA receptors in plant defense, we systematically analyzed their contributions to different aspects of Arabidopsis (Arabidopsis thaliana) plant immunity using the SA-insensitive npr1-1 npr4-4D double mutant. We found that perception of SA by NPR1 and NPR4 is required for activation of N-hydroxypipecolic acid biosynthesis, which is essential for inducing systemic acquired resistance. In addition, both pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are severely compromised in the npr1-1 npr4-4D double mutant. Interestingly, the PTI and ETI attenuation in npr1-1 npr4-4D is more dramatic compared with the SA-induction deficient2-1 (sid2-1) mutant, suggesting that the perception of residual levels of SA in sid2-1 also contributes to immunity. Furthermore, NPR1 and NPR4 are involved in positive feedback amplification of SA biosynthesis and regulation of SA homeostasis through modifications including 5-hydroxylation and glycosylation. Thus, the SA receptors NPR1 and NPR4 play broad roles in plant immunity.  相似文献   
3.
Reliable identification of individual chromosomes in eukaryotic species is the foundation for comparative chromosome synteny and evolutionary studies. Unfortunately, chromosome identification has been a major challenge for plants with small chromosomes, such as the Citrus species. We developed oligonucleotide‐based chromosome painting probes for all nine chromosomes in Citrus maxima (Pummelo). We were able to identify all C. maxima chromosomes in the same metaphase cells using multiple rounds of sequential fluorescence in situ hybridization with the painting probes. We conducted comparative chromosome painting analysis in six different Citrus and related species. We found that each painting probe hybridized to only a single chromosome in all other five species, suggesting that the six species have maintained a complete chromosomal synteny after more than 9 million years of divergence. No interchromosomal rearrangement was identified in any species. These results support the hypothesis that karyotypes of woody species are more stable than herbaceous plants because woody plants need a longer period to fix chromosome structural variants in natural populations.  相似文献   
4.
Radiotherapy is the first-line treatment for all stages of cervical cancer, whether it is used for radical or palliative therapy. However, radioresistance of cervical cancer remains a major therapeutic problem. Consequently, we explored if E-cadherin (a marker of epithelial-mesenchymal transition) and osteopontin could predict radioresistance in patients with locally advanced cervical squamous cell carcinoma (LACSCC). Patients were retrospectively reviewed and 111 patients divided into two groups (radiation-resistant and radiation-sensitive groups) according to progression-free survival (PFS). In pretreated paraffin-embedded tissues, we evaluated E-cadherin and osteopontin expression using immunohistochemical staining. The percentage of patients with high osteopontin but low E-cadherin expression in the radiation-resistant group was significantly higher than those in the radiation-sensitive group (p<0.001). These patients also had a lower 5-year PFS rate (p<0.001). Our research suggests that high osteopontin but low E-cadherin expression can be considered as a negative, independent prognostic factor in patients with LACSCC ([Hazard ratios (95% CI) 6.766 (2.940, 15.572)], p<0.001).  相似文献   
5.
Abstract.  1. The codling moth Cydia pomonella , one of the most important pest insects of apple fruit orchards worldwide, is regarded as a 'sedentary' insect, but the natural populations consist of both mobile and sedentary genotypes that display different dispersal capacity in the field. The current study investigated whether there is a fitness consequence of being mobile in this species by comparing two strains with contrasting levels of mobility obtained through bi-directional selection.
2. Female moths of the sedentary strain were significantly larger, laid more eggs during their lifespan, and both male and female moths of this strain lived longer, when compared with the mobile strain.
3. The age-specific fecundity of female moths from the sedentary strain was significantly greater, in particular between 3 and 5 days after emergence when the peaks of both oviposition and flight capacity occur, relative to the mobile moths, thereby leading to a greater reproductive function.
4. These differences resulted in different demographic parameters between the two strains. The sedentary strain had a significantly greater net reproductive rate ( R o ) and a higher intrinsic rate of natural increase ( r m ), although the generation time ( T ) was similar, hence requiring a shorter time to double the population size, in comparison to the mobile strain.
5. This study provides empirical evidence for the cost of being mobile in C. pomonella . Trade-offs between mobility and fitness might have contributed to the existence of genetic variance for dispersal behaviour in the natural populations and the maintenance of relative sedentariness in the species.  相似文献   
6.
Vallat A  Gu H  Dorn S 《Phytochemistry》2005,66(13):1540-1550
Headspace volatiles from apple-bearing twigs were collected in the field with a Radiello sampler during three different diurnal periods over the complete fruit growing season. Analyses by thermal desorption-GC-MS identified a total of 62 compounds in changing quantities, including the terpenoids alpha-pinene, camphene, beta-pinene, limonene, beta-caryophyllene and (E,E)-alpha-farnesene, the aldehydes (E)-2-hexenal, benzaldehyde and nonanal, and the alcohol (Z)-3-hexen-1-ol. The variations in emission of these plant odours were statistically related to temperature, humidity and rainfall in the field. Remarkably, rainfall had a significant positive influence on changes in volatile release during all three diurnal periods, and further factors of significance were temperature and relative humidity around noon, relative humidity in the late afternoon, and temperature and relative humidity during the night. Rainfall was associated consistently with an increase in the late afternoon in terpene and aldehyde volatiles with a known repellent effect on the codling moth, one of the key pests of apple fruit. During the summer of 2003, a season characterized by below-average rainfall, some postulated effects of drought on trees were tested by establishing correlations with rainfall. Emissions of the wood terpenes alpha-pinene, beta-pinene and limonene were negatively correlated with rainfall. Another monoterpene, camphene, was only detected in this summer but not in the previous years, and its emissions were negatively correlated with rainfall, further supporting the theory that drought can result in higher formation of secondary metabolites. Finally, the two green leaf volatiles (E)-2-hexenal and (Z)-3-hexen-1-ol were negatively correlated with rainfall, coinciding well with the expectation that water deficit stress increases activity of lipoxygenase. To our knowledge, this work represents the first empirical study concerning the influence of abiotic factors on volatile emissions from apple trees in situ.  相似文献   
7.
8.
Radiation‐induced lung injury (RILI) is one of the most common and fatal complications of thoracic radiotherapy. It is characterized with two main features including early radiation pneumonitis and fibrosis in later phase. This study was to investigate the potential radioprotective effects of polydatin (PD), which was shown to exert anti‐inflammation and anti‐oxidative capacities in other diseases. In this study, we demonstrated that PD‐mitigated acute inflammation and late fibrosis caused by irradiation. PD treatment inhibited TGF‐β1‐Smad3 signalling pathway and epithelial–mesenchymal transition. Moreover, radiation‐induced imbalance of Th1/Th2 was also alleviated by PD treatment. Besides its free radical scavenging capacity, PD induced a huge increase of Sirt3 in culture cells and lung tissues. The level of Nrf2 and PGC1α in lung tissues was also elevated. In conclusion, our data showed that PD attenuated radiation‐induced lung injury through inhibiting epithelial–mesenchymal transition and increased the expression of Sirt3, suggesting PD as a novel potential radioprotector for RILI.  相似文献   
9.
The present work developed a novel technique to treat chromite ore processing residue (COPR). The process involved mixing the COPR with sewage sludge followed by pyrolysis. The gaseous organic fraction generated during pyrolysis of sludge was beneficial to Cr(VI) reduction. Process variables, such as the amount of sludge added to COPR (sludge-to-COPR (S/C) ratio), heating temperature, reaction time and particle size, were systematically varied, and their influences on the Cr(VI) reduction in COPR were investigated. Cr(VI) content had decreased greatly, from 3384 mg kg−1 for untreated COPR to less than 30 mg kg−1 for COPR treated at 600 °C.  相似文献   
10.
In reservoirs or lakes, mixing depth affects growth and loss rates of phytoplankton populations. Based on 1-year data from the Zeya reservoir, China, we scaled the mixing depth throughout a whole year by utilizing cluster analysis, and then investigated its influence on phytoplankton dynamics and other physical and chemical parameters. Over the whole year, all physical and chemical parameters except TN and temperature had significant correlations with mixing depth, indicating that mixing depth is one of the important driving factors influencing water environment. According to mixing depth, a year can be divided into three different periods, including the thermally stratified period, isothermally mixed period, and transition period between them. When considering the former two different periods separately, mixing depth had no correlation with the phytoplankton biovolume. However, over the whole year a significant correlation was observed, which indicated that the influence of mixing depth on phytoplankton growth in the Zeya reservoir still followed Diehl’s theory. Furthermore, according to the steady-state assumption, a unimodal curve (mixing depth—phytoplankton biovolume) with a significant peak appearing at a mixing depth of 2 m was observed, closely agreeing with Diehl’ prediction.  相似文献   
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