Influence of Temperature on Growth and Production of Pectenotoxin-2 by a Monoclonal Culture of Dinophysis caudata

The effects of temperature on growth and production of Lipophilic Toxins (LT) by a monoclonal culture of Dinophysis caudata was studied. The cell density of D. caudata increased significantly with increasing temperature, and was the highest under 27, 30, and 32.5 °C. Temperature affected the average specific growth rate (µ) during the exponential growth phase (EG), which increased from 15 °C to 30 °C, and then decreased at 32.5 °C. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed that this strain of D. caudata produced only pectenotoxin-2 (PTX-2) whose concentration increased significantly with incubation period, except at 32.5 °C. It was significantly different between temperatures ≤18 °C, ≥21 °C, and 32.5 °C. The cellular toxin production (CTP, pg·cell⁻¹·day⁻¹) showed variation with growth phase and temperature, except at 32.5 °C. The average net toxin production (R_tox) was not affected by temperature. During EG, the average specific toxin production rate (µ_tox) increased significantly with increase in temperature, reaching a peak of 0.66 ± 0.01 day⁻¹ at 30 °C, and then decreased. Over the entire growth span, µ_tox was significantly correlated to µ, and this correlation was most significant at 27 and 30 °C. During EG, µ_tox was affected by both temperature and growth. This study shows that temperature affects growth and toxin production of this strain of D. caudata during EG. In addition, a positive correlation was found between toxin production and growth.     

Anthracnose of sweet pepper caused by Colletotrichum scovillei in Japan

Severe fruit rot of sweet pepper was found in Shimane, Hyogo, Chiba, Toyama, and Nagano prefectures, Japan from 2005 to 2011. Dark, sunken spots with concentric rings of orange conidial masses appeared on fruits. Pathogenic isolates from diseased fruits in the prefectures were identified as Colletotrichum scovillei. This species was added to the pathogens of sweet pepper anthracnose in Japan. The representative isolate was pathogenic to sweet pepper, tomato and chili pepper fruits, kidney bean pod, azuki bean, pea and strawberry leaves, but a caused no symptoms on cucumber or carrot in inoculation tests.     

High levels of sugars and fructan in mature seed of sweet wheat lacking GBSSI and SSIIa enzymes

Sweet wheat (SW), which lacks functional granule-bound starch synthase I (GBSSI) and starch synthase IIa (SSIIa), accumulates high levels of free sugars in immature seeds. Here, we examined the effects of the lack of these two enzymes on mature kernel composition. Whole grain flour of SW had higher levels of sugars, particularly maltose, slightly higher ash and protein content, approximately two to three times higher lipid levels, and about twice as much total dietary fiber as parental or wild-type lines. Considerably higher levels of low-molecular-weight soluble dietary fiber (LMW-SDF), largely consisting of fructan, were also detected in SW. Although there were no differences in total amino acid levels, the free amino acid content of SW was approximately 4-fold higher than that of wild type, and the levels of certain free amino acids such as proline were particularly high. Thus, we were able to clearly demonstrate that the lack of GBSSI and SSIIa caused dramatic changes in mature seed composition in SW. These compositional changes suggest that SW flour may provide health benefits when used as a food ingredient.     

Specific and non-specific adsorption of inorganic ions I. Evaluation of specific adsorbability by means of minimum concentration for specific adsorption

The Minimum Concentration for Specific Adsorption (MCSA) was defined as a reversal of the charge concentration of the ion at the infinite dilution of sol (adsorbent), or practically at such concentration of sol that equilibrium of the ion Is but negligibly affected by adsorption of the ion.

The MCSAs of 15 species of cations were measured with respect to SiO₂ at pH 4,6,5, and 10; the MCSAs of 10 species of anions were measured with respect to Fe(OH)₃ at pH 4, and 6.5; and the MCSAs of 10 species of anions were measured with respect to Al-coated-SiO₂ at pH 6.5. Relative specificities of the inorganic ions based on the MCSAs at pH 6.5 were as follows:

The MCSAs of cations with respect to SiO₂ and of anions to Fe(OH)₃ and Al-coated-SiO₂ at pH 6.5 had close relationships to ionic potentials and general solubility of the elements in water. Based on these results, the authors concluded that the MCSA could be used u an index of specificity (i.e. covalent bond-forming tendency) of an Jon at adsorption reactions.

The values corresponding to the apparent stability constants of surface complexes formed by adsorption reaction with SiO₂ and cations at pH 4 were calculated from the values of the MCSAs.     

Metyltetraprole activity against plant pathogens with relatively rare cytochrome b haplotypes for azoxystrobin resistance

Journal of General Plant Pathology - Metyltetraprole is a novel quinone outside inhibitor (QoI) fungicide designed to avoid cross-resistance in cytochrome b G143A-harboring QoI-resistant...     

Sulfonylurea-resistant biotypes of Monochoria vaginalis generate higher ultraweak photon emissions than the susceptible ones

All living organisms spontaneously generate ultraweak photon emissions, which originate from biochemical reactions in cells. Current research uses the ultraweak photon emission from organisms as a novel indicator in nondestructive analyses of an organisms living state. This study indicates that ultraweak photon emissions from Monochoria vaginalis are different between resistant biotypes (R) to sulfonylurea (SU) and susceptible biotypes (S). In SU-R biotypes, distinct increases in photon emissions were observed, but there was little increase in SU-S biotypes. In addition, photon emissions from the resistant biotypes of M. vaginalis were suppressed by treatment with P450 inhibitors. This suggests that cytochrome P450 monooxygenase, which plays a crucial role in the metabolic detoxification of SUs, could be associated with the generation of ultraweak photon emissions. Ultraweak photon emissions have a potential use in a novel diagnosis system as an indicator in a nondestructive testing of weeds resistant to SUs.     

Asexual fungus <Emphasis Type="Italic">Verticillium dahliae</Emphasis> is potentially heterothallic

Verticillium dahliae, a soilborne plant pathogen, causes wilt disease in many important crops. We reported previously that the mating type gene MAT1-2-1 is spread to isolates of this asexual fungus. However, we did not determine whether V. dahliae is homothallic or heterothallic because the opposite mating type gene, MAT1-1-1, had not been identified. In the present study, we identified the MAT1-1-1 gene from an isolate lacking MAT1-2-1 and the mating type idiomorphs of V. dahliae. Each isolate we tested contained either the MAT1-1 or MAT1-2 idiomorph, indicating that the asexual fungus V. dahliae is potentially heterothallic.     

Comparative study of the Nicotiana species with respect to water deficit tolerance during early growth

Sixty Nicotiana species were examined for tolerance against various osmotica for seed germination and seedling growth in vitro. The species showed a wide variety of tolerance, and based on the results of the in vitro tests, 31 species were selected and further evaluated for salt and drought tolerance in a glasshouse. The degrees of tolerance of germination among the 57 species toward NaCl were approximately related to those toward mannitol, indicating that the osmolarity plays a majorrole in seed germination. However, the responses during the seedling growth differed in NaCl and mannitol or drought, and there was no correlation between salt and drought tolerance. Based on the responses in vitro and in the glasshouse, N. paniculata and N. excelsior were selected as the salt tolerant species, and N. arentsii as the salt sensitive species. The degrees of accumulation of dry matter and of Na⁺ in the leaves were different in the two tolerant species; during NaCl treatment, N. paniculata and N. arentsii accumulated less dry matter relative to the control plants than N. excelsior, and N. paniculata accumulated more Na⁺ in its leaves than N. excelsior and N. arentsii. It is assumed that the two salt tolerant species have different mechanisms for tolerance to the salt. This revised version was published online in July 2006 with corrections to the Cover Date.