A prodrug approach towards the development of tricyclic-based FBPase inhibitors

For the purpose of reducing the strong CYP3A4 inhibitory potency of diamide prodrug 4, cyclic prodrugs of tricyclic-based FBPase inhibitors were synthesized. Extensive SAR studies led to the discovery of pyridine-containing cyclic prodrug 20, which strongly inhibited glucose production in monkey hepatocytes and also showed weak CYP3A4 inhibitory potency.     

Rotation angle of stem cell division plane controls spiral phyllotaxis in mosses

Journal of Plant Research - The spiral arrangement (phyllotaxis) of leaves is a shared morphology in land plants, and exhibits diversity constrained to the Fibonacci sequence. Phyllotaxis in...     

Activation of SnRK2 by Raf-like kinase ARK represents a primary mechanism of ABA and abiotic stress responses

The Raf-like protein kinase abscisic acid (ABA) and abiotic stress-responsive Raf-like kinase (ARK) previously identified in the moss Physcomitrium (Physcomitrella) patens acts as an upstream regulator of subgroup III SNF1-related protein kinase2 (SnRK2), the key regulator of ABA and abiotic stress responses. However, the mechanisms underlying activation of ARK by ABA and abiotic stress for the regulation of SnRK2, including the role of ABA receptor-associated group A PP2C (PP2C-A), are not understood. We identified Ser1029 as the phosphorylation site in the activation loop of ARK, which provided a possible mechanism for regulation of its activity. Analysis of transgenic P. patens ark lines expressing ARK-GFP with Ser1029-to-Ala mutation indicated that this replacement causes reductions in ABA-induced gene expression, stress tolerance, and SnRK2 activity. Immunoblot analysis using an anti-phosphopeptide antibody indicated that ABA treatments rapidly stimulate Ser1029 phosphorylation in the wild type (WT). The phosphorylation profile of Ser1029 in ABA-hypersensitive ppabi1 lacking protein phosphatase 2C-A (PP2C-A) was similar to that in the WT, whereas little Ser1029 phosphorylation was observed in ABA-insensitive ark missense mutant lines. Furthermore, newly isolated ppabi1 ark lines showed ABA-insensitive phenotypes similar to those of ark lines. Therefore, ARK is a primary activator of SnRK2, preceding negative regulation by PP2C-A in bryophytes, which provides a prototype mechanism for ABA and abiotic stress responses in plants.

Phosphorylation in the activation loop of the Raf-like kinase ARK is critical for SNF1-related protein kinase2 regulation during abscisic acid responses in the moss Physcomitrium (Physcomitrella) patens.     

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.     

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.