Stereochemistry of Pyrethrosin,Cyclopyrethrosin Acetate and Isocyclopyrethrosin Acetate

The acid cyclization product from pyrethrosin has been proved to be a (1:1)-mixture of cyclopyrethrosin acetate containing a Δ³⁽⁴⁾-double bond and isocyclopyrethrosin acetate with a Δ⁴⁽¹⁵⁾-double bond through the reinvestigation. NMR and ORD studies on their derivatives led us to assign revised stereochemistry to pyrethrosin and its related compounds.     

Ostreol A: A new cytotoxic compound isolated from the epiphytic dinoflagellate Ostreopsis cf. ovata from the coastal waters of Jeju Island,Korea

Ostreol A was isolated from cultures of the epiphytic dinoflagellate Ostreopsis cf. ovata from the coastal waters of Jeju Island, Korea. The compound, a non-palytoxin derivative, has a polyhydroxy chain ending with the primary amino group and contains an amide bond, along with two tetrahydropyran rings in the chain. Its chemical structure was elucidated by nuclear magnetic resonance (NMR) spectroscopy methods and confirmed by mass analysis. The compound exhibited significant cytotoxicity in the brine shrimp lethality test at a concentration of 0.9 μg/mL.     

Tribolium castaneum Transformer-2 regulates sex determination and development in both males and females

Tribolium castaneum Transformer (TcTra) is essential for female sex determination and maintenance through the regulation of sex-specific splicing of doublesex (dsx) pre-mRNA. In females, TcTra also regulates the sex-specific splicing of its own pre-mRNA to ensure continuous production of functional Tra protein. Transformer protein is absent in males and hence dsx pre-mRNA is spliced in a default mode. The mechanisms by which males inhibit the production of functional Tra protein are not known. Here, we report on functional characterization of transformer-2 (tra-2) gene (an ortholog of Drosophila transformer-2) in T. castaneum. RNA interference-mediated knockdown in the expression of gene coding for tra-2 in female pupae or adults resulted in the production of male-specific isoform of dsx and both female and male isoforms of tra suggesting that Tra-2 is essential for the female-specific splicing of tra and dsx pre-mRNAs. Interestingly, knockdown of tra-2 in males did not affect the splicing of dsx but resulted in the production of both female and male isoforms of tra suggesting that Tra-2 suppresses female-specific splicing of tra pre-mRNA in males. This dual regulation of sex-specific splicing of tra pre-mRNA ensures a tight regulation of sex determination and maintenance. These data suggest a critical role for Tra-2 in suppression of female sex determination cascade in males. In addition, RNAi studies showed that Tra-2 is also required for successful embryonic and larval development in both sexes.     

Solid-state NMR structures of integral membrane proteins

Abstract

Solid-state NMR is unique for its ability to obtain three-dimensional structures and to measure atomic-resolution structural and dynamic information for membrane proteins in native lipid bilayers. An increasing number and complexity of integral membrane protein structures have been determined by solid-state NMR using two main methods. Oriented sample solid-state NMR uses macroscopically aligned lipid bilayers to obtain orientational restraints that define secondary structure and global fold of embedded peptides and proteins and their orientation and topology in lipid bilayers. Magic angle spinning (MAS) solid-state NMR uses unoriented rapidly spinning samples to obtain distance and torsion angle restraints that define tertiary structure and helix packing arrangements. Details of all current protein structures are described, highlighting developments in experimental strategy and other technological advancements. Some structures originate from combining solid- and solution-state NMR information and some have used solid-state NMR to refine X-ray crystal structures. Solid-state NMR has also validated the structures of proteins determined in different membrane mimetics by solution-state NMR and X-ray crystallography and is therefore complementary to other structural biology techniques. By continuing efforts in identifying membrane protein targets and developing expression, isotope labelling and sample preparation strategies, probe technology, NMR experiments, calculation and modelling methods and combination with other techniques, it should be feasible to determine the structures of many more membrane proteins of biological and biomedical importance using solid-state NMR. This will provide three-dimensional structures and atomic-resolution structural information for characterising ligand and drug interactions, dynamics and molecular mechanisms of membrane proteins under physiological lipid bilayer conditions.     

HPLC法测定新疆阿魏不同部位阿魏酸的含量

建立新疆阿魏中不同部位阿魏酸的高效液相色谱含量测定方法.采用PLATISIL ODS(250 mm×4.6mm,5μm)色谱柱,甲醇～0.1％冰醋酸水溶液(35∶ 65)为流动相,流速1.0 mL/min,检测波长320 nm,柱温30℃.测得阿魏酸进样量在0.440～5.396μg/mL(r=0.9997)范围内与峰面积有良好的线性关系,平均回收率达97.8％,RSD为1.79％(n=9).新疆阿魏胶、根、茎和叶中的阿魏酸含量分别为0.2600、0.0362、0.0225和0.0275 mg/g,胶中阿魏酸的含量远高于根、茎和叶.该方法简便、准确、重复性好,可用于新疆阿魏中不同部位阿魏酸含量的测定.     

荧光高效液相色谱法测定三种失眠模型大鼠脑组织氨基酸类神经递质的含量

目的测定睡眠剥夺大鼠脑组织氨基酸类神经递质的含量。方法复制药物诱导失眠动物模型、平台水环境诱导失眠动物模型、刺激诱导失眠动物模型,以Agilent 1100荧光检测器高效液相系统为检测工具,Agilent ZORBAX SB-Aq(250 mm×4.6 mm,5μm)为色谱柱,柱温25℃,激发波长λex=357 nm,发射波长λem=455 nm,甲醇-50 mmoL/L醋酸钠缓冲液(pH=6.5)为流动相,采取梯度洗脱,测定正常组及模型组大鼠脑组织中谷氨酸(Glu)、甘氨酸(Gly)、γ-氨基丁酸(γ-GABA)、牛磺酸(Tau)的含量。结果谷氨酸、甘氨酸、γ-氨基丁酸、牛磺酸分别在10.06～0.0503、10.13～0.0506、10.05～0.0502、10.03～0.0501μg/mL范围内,其浓度与峰面积呈良好的线性关系(r分别为0.99995、0.99995、0.99985、0.99990)。测得药物诱导失眠大鼠脑组织中Glu、Gly、Tau、γ-GABA的含量为(0.2042±0.0145)、(0.0086±0.0005)、(0.0919±0.0024)、(0.0421±0.0011)μg;平台水环境诱导失眠大鼠脑组织中Glu、Gly、Tau、γ-GABA的含量为(0.2144±0.0159)、(0.0085±0.0004)、(0.0966±0.0035)、(0.0433±0.0012)μg;刺激诱导失眠大鼠脑组织中Glu、Gly、Tau、γ-GABA的含量为(0.1818±0.0043)、(0.0084±0.0005)、(0.0824±0.0033)、(0.0414±0.0018)μg;正常大鼠脑组织中Glu、Gly、Tau、γ-GABA的含量为(0.1744±0.0038)、(0.0085±0.0004)、(0.0791±0.0022)、(0.0406±0.0012)μg。结论本实验建立的方法能满足同时测定大鼠脑组织中谷氨酸、甘氨酸、γ-氨基丁酸、牛磺酸的含量测定的需要,Glu、Tau、γ-GABA与失眠可能存在一定的量效关系,三种失眠动物模型均能较好的反映出脑内氨基酸类神经递质的变化。     

Two androecious mutations reveal the crucial role of ethylene receptors in the initiation of female flower development in Cucurbita pepo

Ethylene is the key regulator of sex determination in monoecious species of the family Cucurbitaceae. This hormone determines which individual floral meristems develop as female or male flowers and the female flowering transition. The sex determination genes discovered so far code for ethylene biosynthesis enzymes, but little is known about the importance of ethylene signaling components. In this paper we characterize two novel ethylene‐insensitive mutations (etr1a‐1 and etr1b) which block the female flowering transition of Cucurbita pepo; this makes plants produce male flowers indefinitely (androecy). Two missense mutations in the ethylene‐binding domain of the ethylene receptors CpETR1A or CpETR1B were identified as the causal mutations of these phenotypes by using whole‐genome resequencing. The distinctive phenotypes of single and double mutants for four etr mutations have demonstrated that the final level of ethylene insensitivity depends upon the strength and dosage of mutant alleles for at least three cooperating ETR genes, and that the level of ethylene insensitivity determines the final sex phenotype of the plant. The sex phenotype ranges from monoecy in ethylene‐sensitive wild‐type plants to androecy in the strongest ethylene‐insensitive ones, via andromonoecy in partially ethylene‐insensitive plants. The induction of female flowering transition was found to be associated with upregulation of CpACS11, CpACO2 and CpACS27, three ethylene biosynthesis genes required for female flower development. A model is proposed herein, integrating both ethylene biosynthesis and receptor genes into the genetic network which regulates sex determination in C. pepo.