Triterpenoids and Flavonoids from the Leaves of Astragalus membranaceus and Their Inhibitory Effects on Nitric Oxide Production

Four new cycloartane triterpenes, named huangqiyegenins V and VI and huangqiyenins K and L ( 1 – 4 , resp.), together with nine known triterpenoids, 5 – 13 , and eight flavonoids, 14 – 21 , were isolated from a 70%‐EtOH extract of Astragalus membranaceus leaves. The structures of the new compounds were elucidated by detailed spectroscopic analyses, and the compounds were identified as (9β,11α,16β,20R,24S)‐11,16,25‐trihydroxy‐20,24‐epoxy‐9,19‐cyclolanostane‐3,6‐dione ( 1 ), (9β,16β,24S)‐16,24,25‐trihydroxy‐9,19‐cyclolanostane‐3,6‐dione ( 2 ), (3β,6α,9β,16β,20R,24R)‐16,25‐dihydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐20,24‐epoxy‐9,19‐cyclolanostan‐6‐yl acetate ( 3 ), and (3β,6α,9β,16β,24E)‐26‐(β‐D ‐glucopyranosyloxy)‐16‐hydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐9,19‐cyclolanost‐24‐en‐6‐yl acetate ( 4 ). All isolated compounds were evaluated for their inhibitory activities against LPS‐induced NO production in RAW264.7 macrophage cells. Compounds 1 – 3, 14, 15 , and 18 exhibited strong inhibition on LPS‐induced NO release by macrophages with IC₅₀ values of 14.4–27.1 μM .     

Identification and fine mapping of a mutant gene for palealess spikelet in rice

In grass, the evolutionary relationship between lemma and palea, and their relationship to the flower organs in dicots have been variously interpreted and wildely debated. In the present study, we carried out morphological and genetic analysis of a palealess mutant (pal) from rice (Oryza sativa L.), and fine mapping the gene responsible for the mutated trait. Together, our findings indicate that the palea is replaced by two leaf-like structures in the pal flowers, and this trait is controlled by one recessive gene, termed palealess1 (pal1). With a large F2 segregating population, the pal1 gene was finally mapped into a physical region of 35 kb. Our results also suggest that the lemma and palea of rice are not homologous organs, palea is likely evolutionarily equivalent to the eudicot sepal, and the pal1 should be an A function gene for rice floral organ identity.     

Octylphenol stimulates resistin gene expression in 3T3-L1 adipocytes via the estrogen receptor and extracellular signal-regulated kinase pathways

Resistin is known as an adipocyte-specific secretory hormone that can cause insulin resistance and decrease adipocyte differentiation. It can be regulated by sexual hormones. Whether environmental estrogens regulate the production of resistin is still not clear. Using 3T3-L1 adipocytes, we found that octylphenol upregulated resistin mRNA expression in dose- and time-dependent manners. The concentration of octylphenol that increased resistin mRNA levels by 50% was approximately 100 nM within 6 h of treatment. The basal half-life of resistin mRNA induced by actinomycin D was lengthened by octylphenol treatment, suggesting that octylphenol decreases the rate of resistin mRNA degradation. In addition, octylphenol stimulated resistin protein expression and release. The basal half-life of resistin protein induced by cycloheximide was lengthened by octylphenol treatment, suggesting that octylphenol decreases the rate of resistin protein degradation. While octylphenol was shown to increase activities of the estrogen receptor (ER) and MEK1, signaling was demonstrated to be blocked by pretreatment with either ICI-182780 (an ERalpha antagonist) or U-0126 (a MEK1 inhibitor), in which both inhibitors prevented octylphenol-stimulated phosphorylation of ERK. These results imply that ERalpha and ERK are necessary for the octylphenol stimulation of resistin mRNA expression. Moreover, U-0126 antagonized the octylphenol-increased resistin protein expression and release. These data suggest that the way octylphenol signaling increases resistin protein levels is similar to that by which it increases resistin mRNA levels; it is likely mediated through an ERK-dependent pathway. In vivo, octylphenol increased adipose resistin mRNA expression and serum resistin and glucose levels, supporting its in vitro effect.     

Wld(S) reduces paraquat-induced cytotoxicity via SIRT1 in non-neuronal cells by attenuating the depletion of NAD

Wld(S) is a fusion protein with NAD synthesis activity, and has been reported to protect axonal and synaptic compartments of neurons from various mechanical, genetic and chemical insults. However, whether Wld(S) can protect non-neuronal cells against toxic chemicals is largely unknown. Here we found that Wld(S) significantly reduced the cytotoxicity of bipyridylium herbicides paraquat and diquat in mouse embryonic fibroblasts, but had no effect on the cytotoxicity induced by chromium (VI), hydrogen peroxide, etoposide, tunicamycin or brefeldin A. Wld(S) also slowed down the death of mice induced by intraperitoneal injection of paraquat. Further studies demonstrated that Wld(S) markedly attenuated mitochondrial injury including disruption of mitochondrial membrane potential, structural damage and decline of ATP induced by paraquat. Disruption of the NAD synthesis activity of Wld(S) by an H112A or F116S point mutation resulted in loss of its protective function against paraquat-induced cell death. Furthermore, Wld(S) delayed the decrease of intracellular NAD levels induced by paraquat. Similarly, treatment with NAD or its precursor nicotinamide mononucleotide attenuated paraquat-induced cytotoxicity and decline of ATP and NAD levels. In addition, we showed that SIRT1 was required for both exogenous NAD and Wld(S)-mediated cellular protection against paraquat. These findings suggest that NAD and SIRT1 mediate the protective function of Wld(S) against the cytotoxicity induced by paraquat, which provides new clues for the mechanisms underlying the protective function of Wld(S) in both neuronal and non-neuronal cells, and implies that attenuation of NAD depletion may be effective to alleviate paraquat poisoning.     

昆虫病原线虫对非生物胁迫的响应机制

昆虫病原线虫是农林害虫生物防治中重要的生防因子之一。它对非生物胁迫的耐受能力决定着线虫在田间的个体生存及控制害虫效果。线虫对环境胁迫的响应是一个整体性的复杂过程, 体现在群体遗传、发育阶段、生理生化和抗逆相关基因的表达调控等不同层次、不同水平上。本文综述了昆虫病原线虫抗逆相关领域的主要研究进展, 重点介绍线虫响应非生物胁迫的生理生化机制和相关抗性基因的分离鉴定, 并对该研究领域发展趋势进行了讨论和展望, 期望为我国研究线虫抗逆机理提供一些新的信息。     

Isolation and molecular characterization of herpesvirus from cultured European eels Anguilla anguilla in Taiwan

A herpesvirus has been isolated for the first time from a population of European eels Anguilla anguilla cultured in a recirculated system in Taiwan. Syncytia formation was detected in EP-1 (eel epidermis) cell cultures inoculated with cell-free homogenates prepared from both integument and visceral organs of moribund fish. Inoculation of homogenates onto EK (eel kidney) cell cultures induced giant cell formation. Subsequent passages produced a consistent and progressive cytopathic effect (CPE) in cell cultures. In this study, EP-1 cell cultures infected with EEHV (European eel herpesvirus) were examined using an electron microscope. Numerous nucleocapsids of about 100 nm in diameter were found within the nucleus of infected cells, whereas enveloped particles were observed within the cytoplasm. The mature viral particle, about 235 nm in diameter, had an electron-dense core with a hexagonal nucleocapsid surrounded by a coarse capsule. Histopathological examination of moribund fish showed epithelial hyperplasia with intracytoplasmic metabolic inclusions in the skin. Macrophage aggregates were found in liver, spleen, and kidney. A pair of primers designed from channel catfish virus and salmonid herpesvirus 1 was used in a polymerase chain reaction. A 402 bp fragment was amplified and cloned from genomic DNA of EEHV. The nucleotide homology was 99% (298 of 300) with DNA polymerase of eel herpesvirus (anguillid herpesvirus). EEHV nucleic acids were detected within melanomacrophages in the skin, liver, spleen and kidney by in situ hybridization (ISH).     

Vaccinia virus N1L protein resembles a B cell lymphoma-2 (Bcl-2) family protein

Poxviruses encode immuno-modulatory proteins capable of subverting host defenses. The poxvirus vaccinia expresses a small 14-kDa protein, N1L, that is critical for virulence. We report the crystal structure of N1L, which reveals an unexpected but striking resemblance to host apoptotic regulators of the B cell lymphoma-2 (Bcl-2) family. Although N1L lacks detectable Bcl-2 homology (BH) motifs at the sequence level, we show that N1L binds with high affinity to the BH3 peptides of pro-apoptotic Bcl-2 family proteins in vitro, consistent with a role for N1L in modulating host antiviral defenses.     

Automatic annotation of protein motif function with Gene Ontology terms

Background  

Conserved protein sequence motifs are short stretches of amino acid sequence patterns that potentially encode the function of proteins. Several sequence pattern searching algorithms and programs exist foridentifying candidate protein motifs at the whole genome level. However, amuch needed and importanttask is to determine the functions of the newly identified protein motifs. The Gene Ontology (GO) project is an endeavor to annotate the function of genes or protein sequences with terms from a dynamic, controlled vocabulary and these annotations serve well as a knowledge base.     

不同降水条件下沙鞭种群非生殖株丛空间格局分析

植物空间分布格局是物种自身生物学特性与环境因素共同作用的结果,非生殖株丛空间分布格局能够揭示物种无性繁殖与种群扩张过程对异质生境的生态学适应机制。利用基于完全随机、泊松聚块和嵌套双聚块模型的点格局方法和群落学调查,分析了沙鞭(Psammochloa villosa)种群非生殖株丛空间分布格局,探讨了空间格局对降水梯度的响应和适应过程。结果表明：(1)聚集分布是沙鞭种群非生殖株丛的主要类型。在89 mm/a、107.8 mm/a、117.4 mm/a、186 mm/a、191.1 mm/a、363 mm/a降水梯度上聚集尺度分别为3—126 cm、9—200 cm、9—129 cm、6—77 cm、2—95 cm、2—96 cm;(2)基于完全随机模型的空间分布格局对降水的响应规律显著,整体表现为随干旱程度加剧,沙鞭种群非生殖株丛聚集尺度从2—96 cm下降至6—77 cm;(3)在107.8 mm/a、117.4 mm/a、191.1 mm/a、363 mm/a降水梯度上,基于泊松聚块模型的空间分布格局分别在15—19 cm、2—6 cm、2—4 cm、9—25 cm尺度正向偏离泊松聚...