南方红豆杉和东北红豆杉中的15种单体化合物对乳腺癌MCF-7细胞增殖的影响

采用MTT法测定南方红豆杉和东北红豆杉中的15种紫杉宁(Taxinine)衍生物对乳腺癌MCF-7细胞增殖的作用.化合物1～15(10-9～10-5mol/L)处理MCF-7细胞48h和72 h后,化合物1(紫杉宁)、2、5、6和10在10-5mol/L显著抑制细胞增殖(P＜0.05,P＜0.01),处理细胞72 h后抑制率分别为44%、30.1%、20.1%、13.3%和23.3%,且在24～72 h范围内具有时间依赖性.     

Polysialic acid limits choline acetyltransferase activity induced by brain-derived neurotrophic factor

Choline acetyltransferase (ChAT), the enzyme synthesizing acetylcholine, is known to be activated by brain derived neurotrophic factor (BDNF). We found that the specific removal of the carbohydrate polysialic acid (PSA) significantly increased BDNF-induced ChAT-activity in embryonic septal neurons. Using a p75 neurotrophin receptor (p75(NTR)) function-blocking antibody and K252a, a-pan tropomyosin related kinase (Trk) inhibitor, we demonstrate that BDNF-induced ChAT activity requires the stimulation of p75(NTR) and TrkB. PSA removal drastically increased radioactive iodinated ([(125)I])BDNF's maximal binding capacity (Bmax), derived from concentrations of [(125)I]BDNF ranging from 1 pM to 3.2 nM. In the presence of unlabeled nerve growth factor to prevent the binding of [(125)I]BDNF to p75(NTR) sites, the impact of PSA removal on the binding capacity of [(125)I]BDNF was greatly reduced. In conclusion, PSA limits BDNF-induced ChAT activity and BDNF-receptor interactions. BDNF-induced ChAT activity is TrkB and p75(NTR) dependent, and upon PSA removal the additional binding of BDNF to its receptors, especially p75(NTR), likely contributes to the maximal ChAT activity observed. In vivo, the ontogenetic loss of PSA in the postnatal period may allow more interactions between BDNF and its receptors to increase ChAT activity and assure the proper development of the cholinergic septal neurons.     

Volatiles released from bean plants in response to agromyzid flies

Liriomyza sativae Blanchard and Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) are two invasive flies in China that have caused economical damage on vegetables and ornamental plants. In this article, we report the profiles of emitted volatiles from healthy, mechanically damaged, and leafminer-damaged bean, Phaseolus vulgaris L., plants. Among 25 emitted volatiles identified, (E)-2-hexen-1-al, (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, (syn)- and (anti)-2-methylpropanal oxime, (syn)-2-methylbutanal oxime, linalool, and (E,E)-α-farnesene were consistently released from damaged bean plants. Combined amounts of these nine compounds made up more than 70% of the total volatiles emitted from each treatment. No qualitative differences in volatile emission were found between bean plants damaged by the two fly species; however, amounts of several major compounds induced by L. huidobrensis damage were significantly higher than those from plants damaged by L. sativae. The mechanically damaged plants released a higher proportion of green leaf volatiles than plants in the other treatments, whereas leafminer-damaged plants produced more terpenoids and oximes. Furthermore, the volatile profiles emitted from plants, damaged by adult leafminers, by second instar larvae, and even the plants with empty mines left by leafminer larvae (the pupal stage) were significantly different. The identification of volatile oximes released from damaged plants was confirmed and is discussed in a behavioral and biological control context.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

A pathogenesis related protein, AhPR10 from peanut: an insight of its mode of antifungal activity

A pathogenesis related protein (AhPR10) is identified from a clone of 6-day old Arachis hypogaea L. (peanut) cDNA library. The clone expressed as a ∼20 kDa protein in E. coli. Nucleotide sequence derived amino acid sequence of the coding region shows its homology with PR10 proteins having Betv1 domain and P loop motif. Recombinant AhPR10 has ribonuclease activity, and antifungal activity against the peanut pathogens Fusarium oxysporum and Rhizoctonia solani. Mutant protein AhPR10-K54N where lys54 is mutated to asn54 loses its ribonuclease and antifungal activities. FITC labeled AhPR10 and AhPR10-K54N are internalized by hyphae of F. oxysporum and R. solani but the later protein does not inhibit the fungal growth. This suggests that the ribonuclease function of AhPR10 is essential for its antifungal activity. Energy and temperature dependent internalization of AhPR10 into sensitive fungal hyphae indicate that internalization of the protein occurs through active uptake.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .The nucleotide sequence of AhPR10 reported in this paper is submitted to NCBI Nucleotide Sequence Database under the Accession number AY726607.     

Protein related to DAN and cerberus (PRDC) inhibits osteoblastic differentiation and its suppression promotes osteogenesis in vitro

Protein related to DAN and cerberus (PRDC) is a secreted protein characterized by a cysteine knot structure, which binds bone morphogenetic proteins (BMPs) and thereby inhibits their binding to BMP receptors. As an extracellular BMP antagonist, PRDC may play critical roles in osteogenesis; however, its expression and function in osteoblastic differentiation have not been determined. Here, we investigated whether PRDC is expressed in osteoblasts and whether it regulates osteogenesis in vitro. PRDC mRNA was found to be expressed in the pre-osteoblasts of embryonic day 18.5 (E18.5) mouse calvariae. PRDC mRNA expression was elevated by treatment with BMP-2 in osteoblastic cells isolated from E18.5 calvariae (pOB cells). Forced expression of PRDC using adenovirus did not affect cell numbers, whereas it suppressed exogenous BMP activity and endogenous levels of phosphorylated Smad1/5/8 protein. Furthermore, PRDC inhibited the expression of bone marker genes and bone-like mineralized matrix deposition in pOB cells. In contrast, the reduction of PRDC expression by siRNA elevated alkaline phosphatase activity, increased endogenous levels of phosphorylated Smad1/5/8 protein, and promoted bone-like mineralized matrix deposition in pOB cells. These results suggest that PRDC expression in osteoblasts suppresses differentiation and that reduction of PRDC expression promotes osteogenesis in vitro. PRDC is accordingly identified as a potential novel therapeutic target for the regulation of bone formation.     

Structural Analysis of a Multifunctional, Tandemly Repeated Inositol Polyphosphatase

Mitsuokella multacida expresses a unique inositol polyphosphatase (PhyAmm) that is composed of tandem repeats (TRs). Each repeat possesses a protein tyrosine phosphatase (PTP) active-site signature sequence and fold. Using a combination of structural, mutational, and kinetic studies, we show that the N-terminal (D1) and C-terminal (D2) active sites of the TR have diverged and possess significantly different specificities for inositol polyphosphate. Structural analysis and molecular docking calculations identify steric and electrostatic differences within the substrate binding pocket of each TR that may be involved in the altered substrate specificity. The implications of our results for the biological function of related PTP-like phytases are discussed. Finally, the structures and activities of PhyAmm and tandemly repeated receptor PTPs are compared and discussed. To our knowledge, this is the first example of an inositol phosphatase with tandem PTP domains possessing substrate specificity for different inositol phosphates.     

The multi-year effects of repeatedly growing cotton with moderate resistance to Meloidogyne incognita

Meloidogyne incognita causes more damage to cotton in the US than any other pathogen. The objective of this study was to document the cumulative effect of moderate resistance on M. incognita population density, root galling, and yield suppression in the southern United States on a moderately resistant cotton genotype grown continuously for three years. Cotton genotypes were Phytogen PH98-3196 (77% suppression of M. incognita), Acala NemX (85% suppression of M. incognita), and Delta and Pine Land DP458 B/R (susceptible standard, 0% suppression). Cotton was grown in fumigated and non-fumigated plots to measure yield loss. Each genotype and nematicide combination was planted in the same place for three years at two sites to document cumulative effects. In 2006, following three years of the different genotypes, all plots at one site were planted with susceptible cotton to document residual effects of planting resistant genotypes. Root galling and nematode population densities in the soil were significantly lower, and percentage yield suppression was numerically lower, when moderately resistant cotton was grown compared to the susceptible standard in both fields in all three years. Differences between susceptible and moderately resistant genotypes are established quickly (after only one season) and then either maintained at similar levels or slightly increased in subsequent years depending on initial nematode levels. However, when susceptible cotton was grown following three years of the moderately resistant genotypes, the nematode suppression provided by moderate resistance was undetectable by the end of the first season. Moderately resistant cotton genotypes are more beneficial than previously reported and should be pursued for nematode management. Rotation of moderately resistant and susceptible cotton could be used along with nematicides to manage root-knot nematodes in a continuous cotton cropping system and reduce selection pressure on the nematodes.     

BEHAVIORAL EVIDENCE FOR FRUIT ODOR DISCRIMINATION AND SYMPATRIC HOST RACES OF RHAGOLETIS POMONELLA FLIES IN THE WESTERN UNITED STATES

The recent shift of Rhagoletis pomonella (Diptera: Tephritidae) from its native host downy hawthorn, Crataegus mollis, to introduced domesticated apple, Malus domestica, in the eastern United States is a model for sympatric host race formation. However, the fly is also present in the western United States, where it may have been introduced via infested apples within the last 60 years. In addition to apple, R. pomonella also infests two hawthorns in the West, one the native black hawthorn, C. douglasii, and the other the introduced English ornamental hawthorn, C. monogyna. Here, we test for behavioral evidence of host races in the western United States. through flight tunnel assays of western R. pomonella flies to host fruit volatile blends. We report that western apple, black hawthorn, and ornamental hawthorn flies showed significantly increased levels of upwind‐directed flight to their respective natal compared to nonnatal fruit volatile blends, consistent with host race status. We discuss the implications of the behavioral results for the origin(s) of western R. pomonella, including the possibility that western apple flies were not introduced, but may represent a recent shift from local hawthorn fly populations.     

MicroRNA-145 suppresses mouse granulosa cell proliferation by targeting activin receptor IB

MicroRNAs (miRNAs) are a class of 21- to 25-nucleotide non-coding RNAs, some of which are important gene regulators involved in folliculogenesis. In this study, we used CCK-8, real-time PCR and Western blot assays to demonstrate that miR-145 inhibits mouse granulosa cell (mGC) proliferation. Combined with the results of luciferase reporter assays that studied the 3′-untranslated region of ACVRIB mRNA, these assays identified ACVRIB as a direct target of miR-145. The ectopic expression of miR-145 reduced the levels of both ACVRIB mRNA and protein and also interfered with activin-induced Smad2 phosphorylation. Altogether, this study revealed that miR-145 suppresses mGC proliferation by targeting ACVRIB.     

TPCK inhibits AGC kinases by direct activation loop adduction at phenylalanine-directed cysteine residues

N-alpha-tosyl-l-phenylalanyl chloromethyl ketone (TPCK) has anti-tumorigenic properties, but its direct cellular targets are unknown. Previously, we showed TPCK inhibited the PDKl-dependent AGC kinases RSK, Akt and S6K1 without inhibiting PKA, ERK1/2, PI3K, and PDK1 itself. Here we show TPCK-inhibition of the RSK-related kinases MSK1 and 2, which can be activated independently of PDK1. Mass spectrometry analysis of RSK1, Aktl, S6K1 and MSK1 immunopurified from TPCK-treated cells identified TPCK adducts on cysteines located in conserved activation loop Phenylalanine-Cysteine (Phe-Cys) motifs. Mutational analysis of the Phe-Cys residues conferred partial TPCK resistance. These studies elucidate a primary mechanism by which TPCK inhibits several AGC kinases, inviting consideration of TPCK-like compounds in chemotherapy given their potential for broad control of cellular growth, proliferation and survival.