New criteria on global exponential stability of bam neural networks with distributed delays and reaction-diffusion terms

This paper presents new theoretical results on global exponential stability of bi-directional associative memory neural networks with distributed delays and reaction-diffusion terms based on the inequality technique, Lyapunov functional, and analysis technique. The results remove the usual assumption that the activation functions are of monotonous or differential character. Exponential converging velocity index is estimated, which depends on the delay kernel functions and system parameters. Finally, two numerical examples are given to show the validity and feasibility of our results.     

RNAi knockdown of Oryza sativa root meander curling gene led to altered root development and coiling which were mediated by jasmonic acid signalling in rice

Jasmonic acid (JA) is a well-known defence hormone, but its biological function and mechanism in rice root development are less understood. Here, we describe a JA-induced putative receptor-like protein (OsRLK, AAL87185) functioning in root development in rice. RNA in situ hybridization revealed that the gene was expressed largely in roots, and a fusion protein showed its localization on the plasma membrane. The primary roots in RNAi transgenic rice plants meandered and curled more easily than wild-type (WT) roots under JA treatment. Thus, this gene was renamed Oryza sativa root meander curling (OsRMC). The transgenic primary roots were shorter, the number of adventitious roots increased and the number of lateral roots decreased as compared to the WT. As well, the second sheath was reduced in length. Growth of both primary roots and second sheaths was sensitive to JA treatment. No significant change of JA level appeared in the roots between the transgenic rice line and WT. Expression of RSOsPR10, involved in the JA signalling pathway, was induced in transgenic rice. Western blotting revealed OsRMC induced by JA. Our results suggest that OsRMC of the DUF26 subfamily involved in JA signal transduction mediates root development and negatively regulates root curling in rice.     

Regeneration of doubled haploid plants by androgenesis of cucumber (<Emphasis Type="Italic">Cucumis sativus </Emphasis>L.)

Six experiments (including pretreatment, embryonic callus induction media, preculture conditions, embryo induction media, embryo germination media, and genotypic effects) were conducted to develop an efficient cucumber (Cucumis sativus L., 2n = 2x = 14) anther culture protocol. Pretreatment and embryo induction were key factors for successful anther culture. Suitable temperature stress depended on the ecotype, i.e., cucumbers from cold areas responded well to cold shock whereas those from temperate areas responded well to heat treatment. The best medium for embryonic callus induction was MS medium supplemented with 4.44 μM BA, 2.26 μM 2, 4-D, 4.64 μM KIN, 3% sucrose and 0.8% agar. For embryo induction, MS medium supplemented with 0.54 μM NAA, 13.32 μM BA, 3% sucrose and 0.8% agar was optimal, and for embryo germination MS medium containing 2.22 μM BA, 6% sucrose and 1.2% agar was best. Using this protocol, we produced callus from 16 genotypes and regenerated plants from three of 20 evaluated. Three embryos per anther and 42 DH per 45 anthers (93% success) were obtained for cv. Ningjia No. 1, which was an improved result over a previous report. The origin of regenerants from microspores was determined by cytological, morphological and AFLP analyses.     

ent-Abietane diterpenoids from Isodon rubescens var. rubescens

ent-Abietane diterpenoids, hebeiabinins A-F (1-5), together with seven known diterpenoids were isolated from leaves of Isodon rubescens var. rubescens. The structures of 1-5 were established on the basis of spectroscopic analyses, including application of 2D NMR spectroscopic techniques. The diterpenoids isolated were evaluated for the cytotoxicity against A549, HT-29, and K562 tumor cells. Compound 5 was the most active with IC(50) value of 0.91 microM against A549 cells.     

Secondary metabolites from Commiphora opobalsamum and their antiproliferative effect on human prostate cancer cells

A cycloartane-type triterpenoid (1), an aliphatic alcohol glycoside (2), an eudesmane-type sesquiterpenoid (3), and a guaiane-type sesquiterpenoid (4) were isolated from the resinous exudates of Commiphora opobalsamum along with six known sesquiterpenoids (5-10). Their structures were established by extensive analysis of their 1D and 2D NMR spectroscopic data and chemical methods. The isolated compounds 1-3 and 5-9 were tested against human prostate cancer cell PC 3 and LNCaP. Among them, 1 and 2 showed moderate antiproliferative effects on human prostate cancer cell lines with IC50 values ranging from 5.7 to 23.6 microM; they were also able to inhibit the expression of androgen receptor (AR) in LNCaP cells. The six sesquiterpenoids were inactive in the bioassays.     

Cytological diploidization and rapid genome changes of the newly synthesized allotetraploids <Emphasis Type="Italic">Cucumis × hytivus</Emphasis>

We used a newly synthesized allotetraploid between C. sativus (2n = 2x = 14, n gametic chromosome number, x haploid chromosome number) and C. hystrix (2n = 2x = 24) to study the genomic events in its early generations. Results from cytological characterization of the F₁ and the allotetraploid progenies showed that the rate of bivalents in meiotic metaphase I of the F₁ was greatly improved by chromosome doubling, and further improved during the selfing process of allopolyploid resulting into relatively diploid-like meiosis. Extensive genomic changes were detected by amplified fragment length polymorphism analysis. The changes mainly involved loss of parental restriction fragments and gaining of novel fragments. The total detectable changes were from 11.1 to 32.1%, and the frequency of losing parental fragments was much higher than that of gaining novel fragments. Some of the changes were initiated as early as in the F₁ hybrid, whereas others occurred after chromosome doubling (polyploid formation). No significant differences were detected in the reciprocal F₁ hybrids and S₀ generations. But the data showed that the frequency of sequence losing in C. sativus was about two times higher than in the C. hystrix. Our results demonstrated that the sequence elimination was the major event of genomic changes, and it might provide the physical basis for the diploid-like meiotic behavior in the diploidization of the newly formed allopolyploids. Moreover, the results suggest that the sequence elimination was not caused by cytoplasmic factors, and might relate to genomic recombination and to the numbers of parental chromosome.     

Effects of venom/calyx fluid from the endoparasitic wasp Cotesia plutellae on the hemocytes of its host Plutella xylostella in vitro

Crude venom and calyx fluid from Cotesia plutellae (Hymenoptera Braconidae) were assayed for biological activity toward hemocytes of Plutella xylostella (Lepidoptera Plutellidae). Venom from C. plutellae displayed high activity toward the spreading of plasmatocytes of P. xylostella early in the incubation period, and the inhibition was more severe as the concentration of venom increased. However, most inhibited hemocytes spread normally after being incubated for 4h. No effects were found toward granular cells from the host. Additionally, the venom from C. plutellae had some lethal effects on hemocytes of P. xylostella at high concentrations. In contrast, when incubated with different concentrations of calyx fluid, the spreading of some hemocytes was inhibited, some began to disintegrate, and some were badly damaged with only the nucleus left. After 4h, the majority of hemocytes died. The same results were observed when hemocytes were incubated in calyx fluid together with venom. These results show that calyx fluid from C. plutellae may play a major role in the suppression of the host immune system, whereas venom from C. plutellae has a limited effect on hemocytes and probably synergizes the effect of calyx fluid or polydnavirus.     

CD99 is a key mediator of the transendothelial migration of neutrophils

Transendothelial migration of leukocytes is a critical event for inflammation, but the molecular regulation of this event is only beginning to be understood. PECAM (CD31) is a major mediator of monocyte and neutrophil transmigration, and CD99 was recently defined as a second mediator of the transmigration of monocytes. Expression of CD99 on the surface of circulating polymorphonuclear cells (PMN) is low compared with expression of CD99 on monocytes or expression of PECAM on PMN. We demonstrate here that, despite low expression of CD99, Fab of Abs against CD99 blocked over 80% of human neutrophils from transmigrating across HUVEC monolayers in an in vitro model of inflammation. Blocking CD99 on either the neutrophil or endothelial cell side resulted in a quantitatively equivalent block, suggesting a homophilic interaction between CD99 on the neutrophil and CD99 on the endothelial cell. Blocking CD99 and PECAM together resulted in additive effects, suggesting the two molecules work at distinct steps. Confocal microscopy confirmed that CD99-blocked neutrophils lodged in endothelial cell junctions at locations distal to PECAM-blocked neutrophils. The CD99-blocked PMN exhibited dynamic lateral movement within endothelial cell junctions, indicating that only the diapedesis step was blocked by interference with CD99. Anti-CD99 mAb also blocked PMN transmigration in a second in vitro model that incorporated shear stress. Taken together, the evidence demonstrates that PECAM and CD99 regulate distinct, sequential steps in the transendothelial migration of neutrophils during inflammation.     

Interactions of phage Mu enhancer and termini that specify the assembly of a topologically unique interwrapped transpososome

The higher-order DNA-protein complex that carries out the chemical steps of phage Mu transposition is organized by bridging interactions among three DNA sites, the left (L) and right (R) ends of Mu, and an enhancer element (E), mediated by the transposase protein MuA. A subset of the six subunits of MuA associated with their cognate sub-sites at L and R communicate with the enhancer to trigger the stepwise assembly of the functional transpososome. The DNA follows a well-defined path within the transpososome, trapping five supercoil nodes comprising two E-R crossings, one E-L crossing and two L-R crossings. The enhancer is a critical DNA element in specifying the unique interwrapped topology of the three-site LER synapse. In this study, we used multiple strategies to characterize Mu end-enhancer interactions to extend, modify and refine those inferred from earlier analyses. Directed placement of transposase subunits at their cognate sub-sites at L and R, analysis of the protein composition of transpososomes thus obtained, and their characterization using topological methods define the following interactions. R1-E interaction is essential to promote transpososome assembly, R3-E interaction contributes to the native topology of the transpososome, and L1-E and R2-E interactions are not required for assembly. The data on L2-E and L3-E interactions are not unequivocal. If they do occur, either one is sufficient to support the assembly process. Our results are consistent with two R-E and perhaps one L-E, being responsible for the three DNA crossings between the enhancer and the left and right ends of Mu. A 3D representation of the interwrapped complex (IW) obtained by modeling is consistent with these results. The model reveals straightforward geometric and topological relationships between the IW complex and a more relaxed enhancer-independent V-form of the transpososome assembled under altered reaction conditions.