The effect of the formulation on the shelf-life of biopesticides based on two colombian isolates of Trichoderma koningiopsis Th003 and Trichoderma asperellum Th034

BackgroundFour biopesticide prototypes formulated as dispersible granules and dry powders based on 2 Colombian isolates of Trichoderma koningiopsis (Th003) and T. asperellum (Th034) were developed. These microorganisms have antagonist activity against Fusarium oxysporum f. sp. lycopersici and Rhizoctonia solani with a reduction in incidence of between 70 and 100% in tomato crops and potato crops, respectively.AimTo determine the effect of the formulation on the shelf-life of 4 biopesticides based on T. koningiopsis Th003 and Trichoderma asperellum Th034 at 3 different temperatures.MethodsThe formulation effect was determined by evaluating the germination of unformulated and formulated conidia (dispersible granules and dry powder) stored at 8, 18 and 28 °C for 18 months. Germination kinetics were used to estimate the shelf-life by using different mathematical models (zero order, first order, second order, Higuchi model, Korsmeyer-Peppas model and polynomial model).ResultsThe products showed high stability of the conidia germination when they were stored at 8 and 18° C, with shelf-lives of 14.4 and 13.9 months for dry powder based on Th003, and 12.0 and 10.8 months for dry powder based on Th034, respectively. Prototypes formulated as dispersible granules stored at the same temperatures (8 and 18 °C) showed lower shelf-lives, with values of 11.6 and 10.9 months for the Th003 product, and 10.7 and 7.2 months for the dispersible granules based on Th034. Significant reductions in germination were observed on unformulated conidia at all storage temperatures evaluated.ConclusionsThe formulation type affected the conidia stability of the 2 Trichoderma spp. Colombian isolates. Dry powder was the prototype with the highest stability and shelf-life at all temperatures evaluated.     

Stimulated production of diosgenin in Dioscorea galeottiana cell suspension cultures by abiotic and biotic factors

Dioscorea deltoidea cell suspension cultures were established in modified Murashige and Skoog medium. The diosgenin production increased from 0.10 g^–1 to 3.98 g^–1 dry cell weight when cells were cultivated in the light and in a growth medium limited in phosphate and sucrose. The addition of 1.3 g of autoclaved fungal mycelium of Alternaria tenuis per litre of cell culture growing in the dark induced the production of 0.04 mg diosgenin g^–1 dry cell weight. In both cases, the production of diosgenin was preceded by a transient induction of isopentenyl diphosphate isomerase activity.     

Determination of new 2,3-benzodiazepines in rat plasma using high-performance liquid chromatography with ultraviolet detection

A method for the analysis of [1-(4-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one] (CFM-2) and its analogues CFM-3, CFM-4 and CFM-5 in rat plasma was developed. The 2,3-benzodiazepines (2,3-BZs) were extracted by liquid–liquid extraction and analyzed using high-performance liquid chromatography (HPLC) with ultraviolet detection (UV) at 240 nm. The method exhibited a large linear range from 0.05 to 2 μg/ml with an intra-assay accuracy for all studied compounds ranging from 92 to 105.5%; whereas the intra-assay precision ranged from 0.59 to 8.16% in rat plasma. The inter-assay accuracy of CFM-2, CFM-4 and their 3-methyl derivatives, CFM-3 and CFM-5 ranged from 92.2 to 107% and the inter-assay precision ranged from 2.17 to 11.9% in rat plasma. The lower limit of detection was 5.5 ng/ml for CFM-2, 6.5 ng/ml for CFM-3, 7 ng/ml for CFM-4 and 8.5 ng/ml for CFM-5 in rat plasma. The pharmacokinetic study demonstrated that 2,3-BZs achieved a peak plasma concentration between 45 and 75 min after drug administration. Moreover, we observed that plasma chromatograms of rats treated with CFM-3, CFM-4 and CFM-5, respectively, showed a peak consistent with CFM-2. Our study suggests that CFM-4, CFM-5 and CFM-3 are prodrugs of CFM-2, in which they are biotransformed in vivo via different metabolic pathways. In particular, CFM-2 has been proven to possess anticonvulsant activity in various models of seizures, acting as α-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor antagonist.     

Phospholipid base exchange enzyme activity in sarcolemmal membranes from the heart of cardiomyopathic hamsters

The activity of phospholipid base exchange enzymes has been evaluated in cardiac sarcolemmal membranes from Syrian Golden hamsters and from a hamster strain (UM-X7.1) characterized by a genetic form of hypertrophic cardiomyopathy. No choline base exchange activity and only a little serine base exchange activity were detected, whereas the ethanolamine base exchange enzyme was found highly active in membranes from both strains. For this reason, the present study is focussed on the ethanolamine base exchange enzyme. The apparent Km for ethanolamine of ethanolamine base exchange enzyme from Syrian Golden membranes and from UM-X7.1 strain membranes are 18 and 32 μM, respectively. The specific activity of the sarcolemmal ethanolamine base exchange enzyme is lower in the UM-X7.1 strain than in Syrian Golden hamsters. The calcium-dependence of the enzyme appears different when the membranes from the two strains are compared. Indeed, after removal of the membrane-bound divalent cations, comparable activities are found in both membrane preparations, whereas, upon addition of Ca²⁺ to the incubation mixtures, the activity of the enzyme is enhanced in the membranes from Syrian Golden strain more than in those from UM-X7.1 strain. The cholesterol content of sarcolemmal membranes is higher in the cardiomyopathic strain than in the Syrian Golden hamsters. A possible relation between changes of the membrane lipid composition and of the ethanolamine base exchange activity is discussed.     

Myosin light chain kinase regulates cell polarization independently of membrane tension or Rho kinase

Cells polarize to a single front and rear to achieve rapid actin-based motility, but the mechanisms preventing the formation of multiple fronts are unclear. We developed embryonic zebrafish keratocytes as a model system for investigating establishment of a single axis. We observed that, although keratocytes from 2 d postfertilization (dpf) embryos resembled canonical fan-shaped keratocytes, keratocytes from 4 dpf embryos often formed multiple protrusions despite unchanged membrane tension. Using genomic, genetic, and pharmacological approaches, we determined that the multiple-protrusion phenotype was primarily due to increased myosin light chain kinase (MLCK) expression. MLCK activity influences cell polarity by increasing myosin accumulation in lamellipodia, which locally decreases protrusion lifetime, limiting lamellipodial size and allowing for multiple protrusions to coexist within the context of membrane tension limiting protrusion globally. In contrast, Rho kinase (ROCK) regulates myosin accumulation at the cell rear and does not determine protrusion size. These results suggest a novel MLCK-specific mechanism for controlling cell polarity via regulation of myosin activity in protrusions.     

Two new species and new records for Pteris (Pteridaceae) from Colombia

A systematic review of the Colombian species of the tribe Pterideae (Pteridaceae) resulted in the discovery of two new species ofPteris:P. muricatopedata andP. albertiae, both in the Deflexa group. Two species are reported for the first time from Colombia:P. bakeri C. Chr. andP. lechleri Mett.     

Drought stress memory in the photosynthetic mechanisms of an invasive CAM species, <Emphasis Type="Italic">Aptenia cordifolia</Emphasis>

Plants are known for their high capacity to acclimatise to fluctuating environmental conditions. A wide range of environmental conditions can lead to suboptimal physiological efficiency. However, recent studies have shown that plants can withstand repeated periods of stress. To find out how they do it, we studied photosynthetic adjustments to repeated water stress in Aptenia cordifolia: a facultative, invasive CAM species. Plants were subjected to three cycles of water deficit, and photosynthetic parameters and chloroplast antioxidants were quantified to gain an understanding of the mechanisms by which they cope with repeated stress periods. Significant modification of the photosystems’ antenna and reaction centres was observed in plants subjected to previous water stress cycles, and this led to higher PSII efficiency than in plants challenged with drought for the first time. These findings underline the biological significance of stress memory and show how plants can adjust their photosynthetic apparatus to fluctuating environmental conditions and thus optimise photosynthesis and photoprotection under drought conditions.     

Gastroduodenal lesions and Helicobacter pylori infection in dyspeptic patients with and without chronic renal failure

BACKGROUND: Patients with chronic renal failure (CRF) often have dyspeptic symptoms and may develop peptic disease or digestive disorders leading to severe gastrointestinal complications. The primary aim of this study was to evaluate the prevalence of peptic lesions and Helicobacter pylori infection, and the severity of dyspeptic symptoms, in dyspeptic patients with and without CRF. Our secondary aim was to investigate whether uremic status may affect the diagnostic efficiency of the [13]C-urea breath test ([13]C-UBT). PATIENTS AND METHODS: We consecutively enrolled in the study 50 dyspeptic patients with chronic kidney failure (mean age 52 +/- 5 years), of whom 11 were on hemodialysis treatment (HD), and 93 subjects (mean age 54 +/- 7 years) with chronic dyspepsia and normal renal function (NRF). All patients completed an oriented and validated questionnaire scoring the severity of nine dyspeptic symptoms (i.e. epigastric pain, epigastric burning, postprandial fullness, early satiety, bloating, belching, nausea and vomiting) and underwent upper endoscopy with multiple bioptic sampling for rapid urease test and histological examination, [13]C-UBT and HpSA test. RESULTS: The prevalences of peptic lesions and H. pylori infection and mean symptom score were 74%, 52% and 3.5 +/- 3, respectively, in dyspeptic patients with CRF and 18%, 36% and 8 +/- 5, respectively, in dyspeptic patients with NRF. The diagnostic accuracy of [13]C-UBT with respect to histological diagnosis was 94% and 97% for dyspeptic patients with and without renal failure, respectively. CONCLUSIONS: 1, A high frequency of peptic lesions and low symptom scores were observed in uremic patients in spite of H. pylori infection; 2, uremic status did not affect the diagnostic accuracy of [13]C-UBT.