Aviglycine and propargylglycine inhibit conidial germination and mycelial growth of <Emphasis Type="Italic">Fusarium oxysporum</Emphasis>f. sp. <Emphasis Type="Italic">luffae</Emphasis>

Two inhibitors, aviglycine and propargylglycine, were tested for their ability to suppress methionine synthesis thus inhibit conidial germination and mycelial growth of Czapek-Dox liquid medium grown Fusarium oxysporum f. sp. luffae μM. The linear inhibition range for mycelial growth was about 7.6–762.9 μM. Although aviglycine did not completely inhibit both conidial germination and mycelial growth, it showed significant inhibitory effect at 1.5 μM. The inhibition range for propargylglycine against conidial germination and mycelial growth were from 0.08 to 8841 μM and from 0.8 to 884.1 μM, respectively. Propargylglycine inhibited conidial germination and mycelial growth at a concentration of 8841 μM. The EC₅₀ values of aviglycine were 1 μM for conidial growth and 122 μM for mycelial growth, and the EC₅₀ values of propargylglycine were 47.7 μM for conidial growth and 55.6 μM for mycelial growth. Supplement of methionine released inhibition of aviglycine or propargylglycine to conidial germination. In addition, a mixture of aviglycine (1.5 μM) and propargylglycine (8841 μM) showed additive inhibitive effect than applied alone on 10 isolates. From these results, both aviglycine and propargylglycine exhibited inhibitory activity, and suggest that they can provide potential tools to design novel fungicide against fungal pathogens.     

Extraction,Antioxidant Activity and Identification of Flavonoids from Root Tubers of <i>Kosteletzkya virginica</i>

Kosteletzkya virginica (K. virginica) is used for revegetation of salt-affected coastal tidal flats and as a raw material of biodiesel. K. virginica root tuber, a biowaste with low economic value, is rich in bioactive compounds. This study aimed to extract and identify flavonoids from K. virginica root tubers. The optimal extraction conditions were 1/25 (w/v) solid/liquid ratio, 40% ethanol concentration at 40°C for 60 min. Under these conditions, 65.2 ± 3.7 mg/g total flavonoid content was extracted from the roots, which were collected from salinized soil in late autumn of the third year. Antioxidant activity was evaluated through 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radical, and superoxide anion scavenging assays. The extracted flavonoids exhibited antioxidant activity in a dose-dependent manner. Five flavonoids, glucoliquiritin apioside, licoisoflavone B, 5-methoxy-7,8-diprenyl- flavone, 7,2′-dihydroxy-6,8-dimethyl-4′,5′-methylenedioxyflavan, and 5,7,4′-trihydroxy-3′-methoxy-6,8-di-Cmethylflavanone, were identified by ultra-performance liquid chromatography–tandem mass spectrometry. Our results suggest that the flavonoids of K. virginica root tubers might be potent antioxidants and can be effectively applied as an ingredient in food and natural medicine.     

Comparative study on direction selectivity and functional organization of the primary visual cortical cells in monkeys and cats

Although the directionally selective cells in many visual cortical areas are organized in columnar manner, the functional organization of direction selectivity of area VI in the monkey still remains unclear. We quantitatively studied the proportion of directionally selective cells, direction selectivity and the functional organization of the striate cortical cells in the monkey and compared those with the cat. The results show that the direction selectivity and directional organization of striate cortical cells in the monkey are significantly weaker than those in the cat, suggesting that the species difference between the two kinds of animal is related to their different anatomic pathways.     

Investigation of low-frequency waves in plasma-filled microwave oscillators

The excitation of microwave oscillations by an electron beam in a hybrid plasma waveguide—a slow-wave structure (a sequence of inductively coupled resonators) with a plasma-filled transport channel—is studied both experimentally and theoretically. It is shown that the governing role in the generation of microwaves and their transmission to a feeder line is played by the spatial and temporal plasma-density variations associated with low-frequency ion plasma oscillations. The microwave pressure gives rise to low-frequency plasma oscillations with a rise time shorter than their period. This nonlinear mechanism for the excitation of low-frequency oscillations has a threshold in terms of the microwave power. The unsteady character of the spatial distribution of the plasma density results in intermittent microwave generation and shortens the duration of microwave pulses.     

Effects of FGF2 and TGFbeta1 on the differentiation of human dental pulp stem cells in vitro

Two crucial growth factors, FGF2 and TGFbeta1, were investigated in this study to determine their inductive effects on the odontoblastic differentiation of human dental pulp stem cells (DPSCs) in vitro. DPSCs were isolated by immunomagnetic bead selection using the STRO-1 antibody, and then co-cultured respectively with FGF2, TGFbeta1 and FGF2+TGFbeta1. The results showed that FGF2 can exert a significant effect on the cell proliferation, while TGFbeta1 or FGF2+TGFbeta1 can initiate an odontoblast-like differentiation of DPSCs. Moreover, FGF2 can synergistically upregulate the effects of TGFbeta1 on the odontoblastic differentiation of DPSCs, as indicated by the increased alkaline phosphatase activity, the polarized cell appearance and secretary ultrastructural features, the formation of mineralized nodules and the gene/protein expression of dentin sialoprotein and dentin matrix protein-1. Together, FGF2 acted primarily on the cell proliferation, while TGFbeta1 and FGF2+TGFbeta1 mainly stimulated the odontoblastic differentiation of DPSCs. This study provides interesting progress in the odontoblastic differentiation of DPSCs induced by FGF2 and TGFbeta1.     

Molecular Characterization of Phytoplasma Associated with Rose Witches'-Broom in China

In 2005, rose plants (Rosa rugosa cv. ‘Plena’) exhibiting typical phytoplasma disease symptoms of stunting, yellowing, witches’‐broom and dieback were observed in Pingyin, Shandong Province, China. The disease, rose witches’‐broom (RoWB), is progressively destructive and can be graft‐transmitted. Polymerase chain reaction (PCR), sequencing of PCR products and electron microscopy were used to investigate the possible association of phytoplasma with RoWB. All results indicated that presence of phytoplasma in the symptomatic rose plants. Sequence alignment of 16S rRNA gene, tuf gene and rp gene confirmed that the phytoplasma associated with RoWB is the causal agent of Paulownia witches’‐broom disease, which might be transmitted from the paulownia tree that is several meters away. To our knowledge, this is the first report of the molecular characterization of phytoplasma infecting rose in China.     

Intensity and Importance of Competition for a Grass (Festuca rubra) and a Legume (Trifolium pratense) Vary with Environmental Changes

How plant competition varies across environmental gradients has been a long debate among ecologists. We conducted a growth chamber experiment to determine the intensity and importance of competition for plants grown in changed environmental conditions. Festuca rubra and Trifolium pratense were grown in monoculturs and in two- and/or three-species mixtures under three environmental treatments. The measured competitive variations in terms of growth (height and biomass) were species-dependent. Competition intensity for Festuca increased with decreased productivity, whilst competition importance displayed a humpback response. However, significant response was detected in neither competition intensity nor importance for Trifolium. Intensity and importance of competition followed different response patterns, suggesting that they may not be correlated along an environmental gradient. The biological and physiological variables of plants play an important role to determine the interspecific competition associated with competition intensity and importance. However, the competitive feature can be modified by multiple environmental changes which may increase or hinder how competitive a plant is.     

Effects of sheep urine on growth characteristics of different life form plants in a Chinese steppe grassland

The effects of sheep urine deposition volume (0, 1, 2 or 4 L/m²) and deposition stage of plant growth (vegetative or reproductive) on the number and size of tillers/branches and the biomass of Stipa bungeana, Artemisia capillaries and Lespedeza davurica in a Chinese steppe grassland were determined. The results indicate that the response of the three plant species to sheep urine deposition differs, and is influenced by both urine deposition volume and deposition stage of plant growth. Urine deposition had a short-term scorch effect on grassland plants, which mainly occurred in the inner zone of urine patches. Urine application had a long-term positive effect on S. bungeana and a long-term negative effect on A. capillaries and L. davurica, which lasted at least two years and decreased with decrease in urine deposition volume. All species growing in the inner zone of urine patches were scorched by sheep urine deposition, some species in the marginal zone of patches were also scorched, while no species were scorched in the outer zones. The reproductive and vegetative stages of A. capillaries and the reproductive stages of S. bungeana and L. davurica were sensitive to sheep urine deposition.