Leaf anatomical structures of <Emphasis Type="Italic">Paphiopedilum</Emphasis> and <Emphasis Type="Italic">Cypripedium</Emphasis> and their adaptive significance

Paphiopedilum and Cypripedium are closely related in phylogeny, but have contrasting leaf traits and habitats. To understand the divergence in leaf traits of Paphiopedilum and Cypripedium and their adaptive significance, we analyzed the leaf anatomical structures, leaf dry mass per area (LMA), leaf lifespan (LL), leaf nitrogen concentration (N _mass), leaf phosphorus concentration (P _mass), mass-based light-saturated photosynthetic rate (A _mass), water use efficiency (WUE), photosynthetic nitrogen use efficiency (PNUE) and leaf construction cost (CC) for six species. Compared with Cypripedium, Paphiopedilum was characterized by drought tolerance derived from its leaf anatomical structures, including fleshy leaves, thick surface cuticles, huge adaxial epidermis cells, lower total stoma area, and sunken stomata. The special leaf structures of Paphiopedilum were accompanied by longer LL; higher LMA, WUE, and CC; and lower N _mass, P _mass, A _mass, and PNUE compared with Cypripedium. Leaf traits in Paphiopedilum helped it adapt to arid and nutrient-poor karst habitats. However, the leaf traits of Cypripedium reflect adaptations to an environment characterized by rich soil, abundant soil water, and significant seasonal fluctuations in temperature and precipitation. The present results contribute to our understanding of the divergent adaptation of leaf traits in slipper orchids, which is beneficial for the conservation of endangered orchids.     

三种高山杜鹃的光合生理生态研究

对大白花杜鹃（Rhododendron decorum）、云南杜鹃（R.yunnanense）和红棕杜鹃（R.rubiginosum）进行了气体交换、叶片性状等研究,以期了解三种杜鹃的光合生理特性及其对环境的适应。结果表明,三种杜鹃的光饱和光合速率（Pmax）与RuBP饱和最大羧化速率（Vc max）、光饱和最大电子传递速率（Jmax）和气孔导度（gs）呈极显著正相关（P≤0.01）,但仅Vc max存在显著的种间差异,说明三种杜鹃的光合能力主要受Vc max影响。叶氮含量、叶片氮在电子传递和在Rubisco中的分配均显著影响Vc max和Jmax。大白花杜鹃的LSP最低,LCP较高,对强光和弱光利用能力都不强,光适应范围较窄。云南杜鹃LCP最低,LSP和Pmax相对较高,对弱光或较强的光照均能利用,光照适应范围相对最广,光合适应能力最强;红棕杜鹃LSP和LCP均为最高,对强光环境的适应性最强。     

Effect of structural modification on the inhibitory selectivity of rutaecarpine derivatives on human CYP1A1, CYP1A2, and CYP1B1

Derivatives of a CYP1A2 inhibitor rutaecarpine were synthesized to have potent and selective inhibition of human CYP1 members. Structural modelling shows a good fitting of rutaecarpine with the putative active site of human CYP1A2. Among the derivatives, 10- and 11-methoxyrutaecarpine are the most selective CYP1B1 inhibitors. 1-Methoxyrutaecarpine and 1,2-dimethoxyrutaecarpine are the most selective CYP1A2 inhibitors.     

The extent of sequence complementarity correlates with the potency of cellular miRNA-mediated restriction of HIV-1

MicroRNAs (miRNAs) are 22-nt non-coding RNAs involved in the regulation of cellular gene expression and potential cellular defense against viral infection. Using in silico analyses, we predicted target sites for 22 human miRNAs in the HIV genome. Transfection experiments using synthetic miRNAs showed that five of these miRNAs capably decreased HIV replication. Using one of these five miRNAs, human miR-326 as an example, we demonstrated that the degree of complementarity between the predicted viral sequence and cellular miR-326 correlates, in a Dicer-dependent manner, with the potency of miRNA-mediated restriction of viral replication. Antagomirs to miR-326 that knocked down this cell endogenous miRNA increased HIV-1 replication in cells, suggesting that miR-326 is physiologically functional in moderating HIV-1 replication in human cells.     

Integration of molecular biology tools for identifying promoters and genes abundantly expressed in flowers of Oncidium Gower Ramsey

Background  

Orchids comprise one of the largest families of flowering plants and generate commercially important flowers. However, model plants, such as Arabidopsis thaliana do not contain all plant genes, and agronomic and horticulturally important genera and species must be individually studied.     

Mycorrhizal Fungi Promote Growth and Nitrogen Utilization by Dendrobium nobile (Orchidaceae)

Mycorrhizal associations play a key role in the life cycle and evolutionary history of orchids. Although most orchid species are tropical and epiphytic, their mycorrhizae are poorly understood compared with those of temperate, terrestrial orchids. To investigate the influences of such fungi on photosynthetic, epiphytic orchids, we inoculated seedlings of Dendrobium nobile with Epulorhiza sp. (S1) or Tulasnella sp. (S3). These fungi had been identified based on their morphological and molecular characters. Both S1 and S3 formed symbiotic associations with our seedlings, promoting their growth and development to various degrees. Results from signature experiments with the 15N stable isotope suggested that the utilization of organic nitrogen by orchid seedlings was significantly improved by S1, but not by S3. Dendrobine contents were significantly higher in all inoculated seedlings. Our findings demonstrate that these mycorrhizal fungi enhance plant growth, their utilization of organic nitrogen, and the accumulation of secondary metabolites in this epiphytic orchid species.