An analysis of age-and size-dependent flowering: A critical-production model

Three critical phenomena of flowering can be recognized in nature: critical age, critical initial size and critical switchover size. In order to understand the ecological significance of these flowering phenomena from the viewpoint of matter production, a simple model of flowering phenomean (critical-production model) was studied, assuming that plant flowering is controlled by the productive capacity of the plant (critical-production model, under the condition that plants forecast environmental conditions affecting matter production. Thus, we concluded that all three critical phenomena are various manifestation of the same critical-production principle. Then, using the model simulation, the reliability of each critical phenomenon for securing a given critical production was investigated in relation to the photosynthetic productivity of the habitat. The main predictions obtained from the simulation were as follows: 1) Only annual and biennial plants will show critical age phenomena, and most biennials will be facultative. 2) Among perennials, the critical initial size phenomenon will appear in low productive habitats, whereas in high productive habitats the critical switchover size phenomenon will be observed.     

Optimum Culture Conditions for Production of Exfoliative Toxin by Staphylococcus hyicus

Optimum culture conditions for the production of exfoliative toxin by Staphylococcus hyicus (shET) were examined. High shET activity was obtained from the culture filtrate of HI and TY broth inoculated with S. hyicus. The pH in these two media ranged from 7 to 8.5 during bacterial culture, while the lowest pH in TS and BHI broth was less than 6. shET activity in the culture filtrate from TY broth inoculated with 10⁷ CFU of S. hyicus per ml was higher than that in TY broth inoculated with 10⁶ and 10⁸ CFU of bacteria per ml. When shET activity in the culture filtrate was measured under various shaking conditions, the culture filtrate shaken at 75 oscillations per min had the highest shET activity of the five shaking conditions. shET activity of the culture filtrate of TY broth to which protease inhibitor had been added was the same as that of TY broth without inhibitor. shET activity in a shaking culture in an Erlenmeyer flask was also the same as that in sac culture and that in shaking culture using a shaking (Sakaguchi) flask. shET activity in TY broth supplemented with 100 mM glucose was significantly lower than that in TY broth without glucose. Based on the above results, the optimum culture conditions for the production of shET were as follows: inoculation of 3 × 10⁹ CFU of S. hyicus strain P-1 into 300 ml of TY broth in a 2,000-ml Erlenmeyer flask, and incubation at 37 C with shaking at 75 oscillations per min. Then shET activity of the culture filtrate under appropriate culture conditions was measured after various incubation periods. shET activity was detected 6 hr after inoculation, reached the maximum (2⁵³ exfoliative unit/0.1 ml) at 16 hr and decreased between 20 and 48 hr. Thus, the optimum incubation period was determined to be 16 hr. Then the optimum concentration of ammonium sulfate for isolation of shET from the culture filtrate under appropriate culture conditions was examined. The greatest shET activity was obtained from the fraction salted out with 90% saturated ammonium sulfate. Thus, the optimum concentration of ammonium sulfate for the isolation of shET was determined to be 90% saturation.     

Puccinia carici-adenocauli, a new rust fungus onCarex, and its anamorph,Aecidium adenocauli

Field observations and inoculation experiments showed thatAecidium adenocauli onAdenocaulon himalaicum was an anamorph of aPuccinia onCarex hakonensis andC. uda. From comparative morphology with caricicolous puccinias, the rust on theseCarex species was considered as a new species and was named asPuccinia carici-adenocauli. Contribution No. 142, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba     

Monoamine metabolites,iron induced seizures,and the anticonvulsant effect of tannins

Intracortical injections of iron ions have been shown to induce recurrent seizures and epileptic discharges in the EEG. (–)-Epigallocatechin (EGC) and (–)-epigallocatecatechin-3-O-gallate (EGCG), isolated from green tea leaves, have been reported to prevent or diminish the occurrence of epileptic discharges induced by iron ions, and to inhibit catechol-O-methyltransferase. Iron ions significantly increased DOPAC and HVA levels in the intrastriatal perfusate 140 and 180 minutes, respectively, after injection. EGC and EGCG inhibited the increases induced by iron ions. Furthermore, EGCG decreased the HVA level in the perfusate 200 minutes after injection whether or not iron ions were injected. Iron ions had no effect on the 5-HIAA level, and EGC and EGCG raised it. These results suggest that formation of an epileptic focus induced by iron ions might be accompanied by activation of dopaminergic neurons, and that EGC and EGCG inhibit that hyperactivity.     

H2 production from starch by a mixed culture of Clostridium butyricum and Rhodobacter sp. M[h]19

A photosynthetic bacterium having ability to produce H2 from acetic, butyric and lactic acids, Rhodobacter sp. M-19 was isolated. H2 was produced from starch in a batch culture by Clostridium butyricum and in a two-step batch culture by C. butyricum and Rhodobacter sp. M-19 in yields of 1.9 and 3.6 mol H2/mol glucose, respectively. A mixed culture of C. butyricum and Rhodobacter sp. M-19 produced H2 from starch with a yield of 6.6 mol H2/mol glucose in a fed-batch culture. © Rapid Science Ltd. 1998     

H2 production from starch by a mixed culture of Clostridium butyricum and Enterobacter aerogenes

A mixed continuous culture of Clostridium butyricum and Enterobacter aerogenes removed O2 in a reactor and produced H2 from starch with yield of more than 2 mol H2/mol glucose without any reducing agents in the medium. Co-immobilized cells of the bacteria on porous glass beads evolved H2 from starch at 1.3 l/l.h, with H2 yield of 2.6 mol H2/ mol glucose at dilution rate of 1.0 h–1 in a continuous culture.     

Native Trichoderma strains isolated from Bangladesh with broad spectrum antifungal action against fungal phytopathogens

Nineteen Trichoderma isolates, collected from different locations in Bangladesh, were characterised through phenotypic, biochemical and molecular means. Besides, they were assessed for their antifungal action in vitro. The isolates were divided into three groups: T. asperellum, T. virens and T. harzianum. A dual culture assay and a culture filtrate assay against 6 phytopathogens revealed that 9 of the 19 isolates showed significant antifungal activities. The isolate T. harzianum TR05 showed the highest inhibition against Fusarium oxysporum, Rhizoctonia solani, Fusarium circinatum and Phomopsis vexans, followed by T. asperellum TR08 and T. virens TR06. TR08 had the highest inhibition against Sclerotium rolfsii and Pythium aphanidermatum, followed by TR05 and TR06. These findings were in agreement with their activities of extracellular hydrolytic enzymes, including chitinase, β-1,3-glucanase, and proteinase. Our results suggest that isolates TR05, TR06 and TR08 have the potential to be effective biocontrol agents against the phytopathogenic fungi.