The smell and odorous components of dried shiitake mushroom, Lentinula edodes VI: increase in odorous compounds of dried shiitake mushroom cultivated on bed logs

Odor is one of the most important characteristics affecting consumer preference for dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler]. In our previous studies, we found that the odor content of commercial dried products was too weak for most people, and that the odorous compound content could be increased by adding amino acids to sawdust media. Currently, however, bed-log cultivation is used to produce fruiting bodies for dried products. The purpose of this study was to fi nd a method to increase the content of odorous compounds in dried products cultivated on bed logs. Pressure injection of amino acids from the side of the bed log was the most effi cient method, but it had some problems. Hence, a simpler and less troublesome method was developed, i.e., injecting amino acid solution from small bottles set in deep holes bored in the sides of the bed logs. In fruiting bodies cultivated on bed logs injected with amino acid solution by the improved method, the mean contents of lentinic acid, a precursor of the odorous compound lenthionine, approximately doubled compared to that in the untreated logs, although the infi ltration area of the solution injected by the improved method was smaller than that by the former method.     

Isolation and characterization of a low molecular weight peptide contained in sourdough

To investigate a sourdough-specific peptide, low molecular weight peptides were extracted from sourdough. The peptide fraction was subjected to two kinds of chromatography to separate the peptides. Reverse-phase chromatography of the peptide fraction in the sourdough showed certain specific peptides. The specific peptide fraction was further separated by gel filtration chromatography. Liquid chromatography tandem mass spectrometry analysis identified one of the peptides as VPFGVG (six-mer). This sequence was estimated to occur at the 287-292 position of a low molecular weight glutenin subunit. The peptide (designed as SDP1) was produced by proteases derived from wheat flour. SDP1 showed angiotensin-converting enzyme (ACE) inhibitory activity, and the 50% inhibitory peptide concentration (IC50) was 336 microM. It is possible that the SDP1 peptide partially confers ACE inhibitory activity in sourdough.     

Avian predation on wild and cultured sea urchin <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis> in a rocky shore habitat

ABSTRACT:   The present study reports the annual variation in consumption of the sea urchin Strongylocentrotus intermedius by avian predators on a rocky shore where the culture of sea urchins has been conducted. Carrion crow and a few gull species were the most abundant avian predators and consumed a large number of sea urchins. Crows consumed mostly natural sea urchins, approximately 36 kg ww/ha per year on the intertidal rocky bench, but the gull species consumed mostly cultured sea urchins, approximately 100 kg ww/ha per year in the culture area. The seasonal variation in the amount of sea urchins consumed by crows was higher than that by the gull species, presumably because of the difference in foraging behavior in association with the seasonal tidal cycle. The natural sea urchins consumed are an allochthonous input from the subtidal to the intertidal habitat, and thus, crow predation may not affect the natural and the cultured populations of the sea urchin. The gull species consumed much of the cultured sea urchin, and thus, may be regarded as an effective predator causing damage to sea urchin culture. The results suggest that further studies are needed to determine why the gull species selectively feed on cultured sea urchins.     

Assessing raindrop impact energy at the forest floor in a mature Japanese cypress plantation using continuous raindrop-sizing instruments

The raindrop size distribution of throughfall and open rainfall was monitored continuously during a rainfall event using laser raindrop-sizing instruments (LD gauges), in order to calculate the raindrop impact energy in a plantation of mature Japanese cypress (Chamaecyparis obtusa), where surface erosion at the forest floor had been a problem. Data from two rainfall events were analyzed. The LD gauges recorded qualitative raindrop size distribution, and the capture rate during each rainfall event was used to manipulate raindrop data quantitatively. Throughfall and open rainfall comparisons revealed several important differences. First, throughfall raindrops were fewer in number and larger in size than open rainfall drops. In one rainfall event, for example, throughfall raindrops were less than one-fifth as frequent as open rainfall raindrops; in addition, the maximum throughfall raindrop diameter was 6.35mm compared to 3.31mm for open rainfall raindrops. Second, throughfall raindrops that were larger than the largest open rainfall raindrops comprised 63.8% of the throughfall precipitation by volume. Third, total raindrop impact energy from throughfall was over twice that of open rainfall. Moreover, comparison of throughfall events implied that throughfall raindrops did not always have a uniform distribution between different events or among different periods of time in one rainfall event, in contrast to findings in previous studies which showed that throughfall raindrops had a uniform size distribution independent of rainfall intensity. It is possible that an abrupt transition of throughfall intensity from low to high changes the distribution of throughfall raindrops.     

An avirulence gene to rice cultivar K60 is located on the 1.6-Mb chromosome in <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis> isolate 84R-62B

A Japanese differential rice cultivar K60 was tested with 114 F₁ cultures of Magnaporthe oryzae from a cross between isolates 84R-62B and Y93-245c-2. Segregation patterns of avirulence and virulence in the progeny suggested that avirulence on cv. K60 was controlled by a single gene derived from 84R-62B and tentatively named AvrK60. In the F₁ population, AvrK60 cosegregated with avirulence gene AvrPik on a small 1.6-Mb chromosome of 84R-62B and with the 1.6-Mb chromosome itself. Therefore, we suggest that, along with AvrPik, AvrK60 is also located on the 1.6-Mb chromosome of 84R-62B.     

Interference with cell-to-cell movement of <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> by transient overexpression of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> KELP homologs from different plant species

The KELP protein of Arabidopsis thaliana (AtKELP), which binds to the Tomato mosaic virus (ToMV) movement protein in vitro, can interfere with cell-to-cell movement of the virus under transient overexpression conditions. In this study, we constructed expression plasmids encoding a fluorescent protein fused to AtKELP or to its homolog from Brassica, Nicotiana, Solanum, or Oryza species. When expressed transiently, all the AtKELP homologs inhibited the cell-to-cell movement of ToMV with different efficiencies. The results of domain swapping between two selected AtKELP homologs suggest the importance of combination between the N- and C-terminal half regions for high inhibitory function.     

Glucosinolate metabolism,functionality and breeding for the improvement of Brassicaceae vegetables

Unique secondary metabolites, glucosinolates (S-glucopyranosyl thiohydroximates), are naturally occurring S-linked glucosides found mainly in Brassicaceae plants. They are enzymatically hydrolyzed to produce sulfate ions, D-glucose, and characteristic degradation products such as isothiocyanates. The functions of glucosinolates in the plants remain unclear, but isothiocyanates possessing a pungent or irritating taste and odor might be associated with plant defense from microbes. Isothiocyanates have been studied extensively in experimental in vitro and in vivo carcinogenesis models for their cancer chemopreventive properties. The beneficial isothiocyanates, glucosinolates that are functional for supporting human health, have received attention from many scientists studying plant breeding, plant physiology, plant genetics, and food functionality. This review presents a summary of recent topics related with glucosinolates in the Brassica family, along with a summary of the chemicals, metabolism, and genes of glucosinolates in Brassicaceae. The bioavailabilities of isothiocyanates from certain functional glucosinolates and the importance of breeding will be described with emphasis on glucosinolates.     

Characterization of cadmium-tolerant carrot cells in response to cadmium stress

Non-tolerant (CW) and Cd-tolerant (CCdl) carrot (Daucus carota L.) cells were compared for their response to cadmium (Cd). The CCdl cells were induced by selection from the CW cells on a B5 medium containing 100 µM Cd. The CCdl cells were more tolerant to Cd than the CW cells. In an 80 µM Cd treatment, the growth rate (8 d/O d) based on the fresh weight of the CCdl cells and CW cells was 69 and 24%, respectively, compared to the controls. Cd stress led to the decrease of the total glutathione content and to the increase of the contents of non-protein thiols (t-SH, phytochelatins) and Cd in both types of cells. Under Cd stress, the contents of t-SH and Cd of the CW cells were higher than those of the CCdl cells. The CW cells in the 80 and 160 µM Cd treatments accumulated Cd with the increase in time. In contrast, the Cd content in the CCdl cells in all the treatments and in the CW cells in the 40 µM Cd treatment gradually decreased after 1 d. In an additional experiment, both types of cells pretreated with 20–80 µM Cd for 1 d were transferred to a Cd-free medium. The CCdl cells in all the pretreatments continuously excluded Cd over a 4-d period, unlike the CW cells. Therefore, a larger depletion of Cd was found in the CCdl cells, which may be partially attributed to Cd tolerance.