Studies. were undertaken to investigate the cause of the bacteriostatic activity of spinach leaves against Listeria monocytogenes. Listeria monocytogenes was inoculated at the concentration 104 cells/ml in raw, autoclaved and vacuum filtration sterilized spinach macerates as well as in tryptic soy broth used as control. The concentrations after 24 h at 28C were 105, 5 × l06 and 105 cells/ml in respective spinach macerates and 4 × l08 cells/ml in tryptic soy broth. The anti-Listeria activity was still present in spinach macerates sterilized by vacuum filtration but strongly reduced in autoclaved macerates. Serial dilutions of freeze-dried spinach were tested on the growth of Listeria monocytogenes in tryptic soy broth. The minimum concentration for maximum inhibition was 10 mg·ml–1. The growth of Listeria monocytogenes in tryptic soy broth in mixed cultures with different microbial species isolated from spinach was not inhibited. In conclusion, the bacteriostatic activity against Listeria monocytogenes might be due to antimicrobial compounds present in spinach leaves.
Aspergillus niger B-1 (CMI CC 324626) extracellular RNase (RNase B1) was purified to homogeneity. It was found to contain two isoforms of 32- and 40-kDa glycoproteins, sharing a 29-kDa protein moiety. Optimal RNase activity was observed at 60 °C and pH 3.5. In `Almog' peach [Prunus persica (L.) Batsch (Peach Group) `Almog'] and `Murcott' tangerine (Citrus reticulata Blanco `Murcott') the enzyme inhibited pollen germination and pollen tube growth in vitro as well as in vivo. In field experiments, spray application of the RNase caused a reduction in `Fantasia' nectarine [Prunus persica (L.) Batsch (Nectarine Group) `Fantasia'] fruit set and interfered with embryo development. The biological effect of the RNase may be of horticultural value, due to its potential to control fertilization.
The effects of lingonberry (Vaccinium vitis-idaea L.) extracts on activator protein-1 (AP-1), nuclear factor-kappaB (NF-κB), and mitogen-activated protein kinases (MAPKs) were evaluated. Pretreatment of JB6 P+ mouse epidermal cells with lingonberry extracts produced a dose-dependent inhibition of AP-1 and NF-κB induced by either 12-O-tetradecanoylphorbol-13-acetate (TPA) or ultraviolet-B (UVB) light. Lingonberry extracts blocked UVB-induced phosphorylation of MAPK family members ERK1, ERK2, and p38, but not JNK. Lingonberry extracts also prevented TPA-induced phosphorylation of ERK1 and ERK2. Results of soft agar assays indicated that lingonberry extracts suppressed TPA-induced neoplastic transformation of JB6 P+
cells in a dose-dependent manner. Lingonberry extracts also induced the apoptosis of human leukemia HL-60 cells in a dose-independent manner. These results suggest that ERK1 and ERK2 may be inhibited by lingonberries, which results in suppression of AP-1 and neoplastic transformation in JB6 P+ cells and causes cancer cell death by an apoptotic mechanism in human leukemia HL-60 cells.
Allelopathy has traditionally been defined as the inhibitory effect of compounds released by one plant on another plant. A broader but less accepted definition of the term includes effects of plants on microorganisms that are mediated by
). In addition, the inhibitory effects showed an obvious dose-dependent manner; when the concentration of fungicide increased, the colony diameter decreased ( Fig. 1 ). Table 1. Inhibitory effect of five fungicides on mycelium growth of B. cinerea
and 4 ). The 4 and 10 mmol·L −1 strontium treatments had a significant inhibitory effect on the growth of Chinese cabbage seedlings. The RFW and leaf number of Chinese cabbage seedlings were reduced, and the photosynthetic activity was slightly
Alexa-488, we generated protoplasts after tissue incubation. At 5 m m sucrose, latrunculin-B, but not phloridzin, exerted a strong inhibitory effect on Alexa-488 accumulation ( Fig. 3 ). The low levels of Alexa-488 accumulated at this concentration (and
incubation under alternating light (16-h photoperiod) at a room temperature of 22 ± 2 °C (n = 25). Effect of temperature and light on germination. At all the temperatures tested, alternating light (16-h photoperiod) was inhibitory for seed germination of 9
development ( Dennis and Nitsch, 1966 ) led to the assumption that seed-derived GAs inhibit flower formation in apple ( Chan and Cain, 1967 ). Dennis and Neilsen (1999) suggested that the inhibitory effect of GAs from the seeds on flower formation is not
revealed that 3,5-DCQA was the most inhibitory component (EC 50 = 2.2 g·L −1 ) in an extract of the outer tissues of ‘Beauregard’ sweetpotato storage roots ( Stange et al., 2001 ). Concentrations were greatest in cortex tissue, indicating that 3,5-DCQA