Modelling flowering of plants using time-to-event methods

Climate and environmental factors are known to influence the propensity of plants to flower. In order to capture the time dynamics in the underlying biological processes, this paper proposes to use a grouped-data survival analysis methodology. We formulate a semi-parametric model for the hazard rate of flowering, which allows all available climatic and environmental data to be included. Estimation can be carried using a generalized linear model approach. In addition, the model can be validated by means of recently developed residual-based model-checking procedures similar to what is available for ordinary regression models. The main finding is that the model proposed captures the major trends and is a first step in the direction of a model-based quantification of some climatic and environmental factors that influence the flowering of plants.     

Morphological patterns in a world collection of <Emphasis Type="Italic">Cleome gynandra</Emphasis>

Cleome gynandra L. is a leafy vegetable native to sub-Saharan Africa and Asia and cultivated on dry areas. The plant plays an important role in the food and nutrition security of local communities. The objective of this study was to illustrate variation and diversity in the Cleome collection held at the World Vegetable Center. In total, 242 accessions were cultivated and morphologically characterized and analyzed. The gynophore and filament, both important organs of the flower, played a key role in taxonomical identification. High morphological variation was detected in traits including plant height, pod length, leaf size, flower color, and earliness. Distinct morphological differentiation was detected between Asian and African accessions. On average, the African accessions were larger, less uniform and later in flowering and seed maturation than the Asian accessions. The results were used to establish a core collection of 49 Cleome accessions. Gaps in the current collection were detected. High within-accessions diversity challenges the existing ex situ conservation system; to maintain diversity, seed should be collected from a large number of plants, both during the collection mission and in ex situ regeneration. The results are relevant for germplasm collection strategies and regeneration protocols for good genebank practices.     

Induction of morphogenesis,branching and conidiogenesis in Fomes annosus

In Fomes annosus the addition of L-threonine induces specifically branching and septum formation in the leading hyphae of the mycelium. The formation of conidia is stimulated by the combination of light and dark phases and starvation.     

Conformational analysis of the fungicide fenpropimorph by molecular mechanics calculations and NMR spectroscopy

Fenpropimorph is an inhibitor of Δ8→Δ7-isomerase and Δ14-reductase in fungi and cycloeucalenol-obtusifoliol-isomerase and Δ8→Δ7-isomerase in higher plants. A detailed conformational analysis of the most potent enantiomer (S)-fenpropimorph is described. The conformational analysis is based on three different methods: molecular mechanics calculations. NMR spectroscopy and X-ray crystallography. In solution several conformations coexist. The molecular mechanics calculations using MM2(85) show a folded conformation of the unprotonated form of fenpropimorph to be stabilized by at least 3 kcal mol^?1 relative to the next lowest energy conformer, suggesting only one conformation of fenpropimorph to be present. A corresponding stabilization of the protonated form (5.4 kcal mol^?1) is obtained. However, this stabilization is found partly to be due to attractive steric interactions and may be a phenomenon occurring only in vacuum. In the solid state, fenpropimorph exists in an L-shaped conformation resembling one of the low-energy conformers obtained with MM2(85). Based on comparison with the natural substrate, a totally extended conformation of fenpropimorph is suggested to be the biologically active conformation for interaction with the Δ8 → Δ7-isomerase in fungi.     

Use of chromametry and digital photography for objective measurement of skin color in clinically normal dogs

OBJECTIVE: To evaluate whether skin erythema in clinically normal dogs can be quantified by use of chromametry and image analysis of digital photographs. ANIMALS: 9 German Shepherd Dogs and 10 mixed-breed dogs. PROCEDURE: Hair was clipped at 7 sites on the body. Skin erythema was evaluated at the axillary region, right and left lateral aspect of thorax, right and left loin area (ie, part of the back between the thorax and pelvis), right and left groin area (ie, the junctional region between the abdomen and thigh), metatarsal digital pad, and on the nose. Replicate measurements were done by use of chromametry and image analysis of digital photographs, using erythema values in accordance with the Committee International d'Eclairage (CIE)-Lab color system. RESULTS: Repeatability was high for both techniques. Within-dog variation was lower than between-dog variation. Between-dog variation was high for both groups of dogs. Interregional variation was significant in German Shepherd Dogs and mixed-breed dogs. Erythema values revealed symmetry between the right and left lateral aspects of the thorax and loin and groin areas. CONCLUSIONS AND CLINICAL RELEVANCE: Precise objective methods are available for skin erythema quantification. Chromametric and photographic erythema values had a high within-dog reproducibility. Between-dog variability was high for German Shepherd Dogs and mixed-breed dogs as was regional variation, indicating differences in color among dogs.     

Evaluation of skin erythema by use of chromametry and image analysis of digital photographs after intradermal administration of histamine in dogs

OBJECTIVE: To investigate whether the degree of erythema during an induced erythematous reaction, the histamine skin test reaction, can be assessed objectively by use of chromametry and image analysis of digital photographs. ANIMALS: 9 pet dogs (6 Golden Retrievers and 3 yellow Labrador Retrievers). PROCEDURE: Histamine phosphate was injected intradermally, and erythema of the wheal reaction was evaluated during the hour that followed. This was done by use of clinical scores, chromametry, and image analysis of digital photographs. Method reproducibility was tested for visual evaluation of printouts of digital photographs and for image analysis of the same photographs. RESULTS: The coefficient of variation of the technically derived erythema values was < 10%. The reproducibility of image analysis was high and the range of agreement between observers narrow. Using chromametry, it was not possible to differentiate between various degrees of erythema intensity as visually perceived. In contrast, use of image analysis of digital photographs enabled discrimination of slight erythema from moderate and marked erythema. The dynamics of reaction measured by chromametry followed the clinical observation. CONCLUSIONS AND CLINICAL RELEVANCE: Chromametric values are comparable to those obtained by visual inspection. As the result of standardized conditions, chromametry is preferred over digital photography.     

Evaluation of binary solvent mixtures for efficient monoacylglycerol production by continuous enzymatic glycerolysis

This study was aimed at evaluating different binary solvent mixtures for efficient industrial monoacylglycerol (MAG) production by enzymatic glycerolysis. Of all investigated cases, the binary mixture of tert-butanol:tert-pentanol (TB:TP) 80:20 vol % was the most suitable organic medium for continuous enzymatic glycerolysis, ensuring high MAG formation in a short time, reasonable solvent price, and easy handling during distillation/condensation processing. A minimum solvent dosage of 44-54 wt % of the reaction mixture was necessary to achieve high MAG yields of 47-56 wt %, within 20 min. The melting and boiling points of the TB:TP mixture were estimated to be 7 and 85 degrees C, respectively, using thermodynamic models. These predictions were in good agreement with experimentally determined values. In spite of the high reaction efficiency in the binary TB:TP system, the mixture of glycerol and sunflower oil (containing 97.1% triacylglycerol) yielded surprisingly a liquid/liquid phase split behavior even at high temperatures (>80 degrees C). This in contrast to thermodynamic model calculations suggested full miscibility in all proportions. These findings suggest that enhanced reaction efficiency in organic solvent also depends upon aspects other than the system homogeneity such as reduced viscosity, reduced mass transfer limitations, and the accessibility of the substrate to the active site of the enzyme.     

Toxicity of Peracetic Acid to Fish: Variation among Species and Impact of Water Chemistry

There has been strong interest in the use of peracetic acid (PAA) in aquaculture as it can be used to disinfect water and hard surfaces and thereby eliminate or lower the burden of fish pathogens. Unfortunately, there has been little research on the toxicity of PAA to fish. Twelve species of fingerling fish that are important to aquaculture were exposed to PAA for 24 h in static toxicity bioassays in well water. These fish were: fathead minnow, Pimephales promelas; black‐nose crappie, Pomoxis nigromaculatus; bluegill, Lepomis macrochirus; blue tilapia, Oreochromis aureus; channel catfish, Ictalurus punctatus; golden shiner, Notemigonus crysoleucas; goldfish, Carassius auratus; grass carp, Ctenopharyngodon idella; largemouth bass, Micropterus salmoides; rainbow trout, Oncorhynchus mykiss; sunshine bass, Morone chrysops × M. saxatilis; and walleye, Sander vitreus. Median lethal concentration (LC₅₀) values were estimated with the trimmed Spearman–Karber method using nominal PAA concentrations. The mean 24‐h LC₅₀ values ranged from 2.8 to 9.3 mg/L PAA. Fathead minnow were very sensitive and blue tilapia were very tolerant to PAA exposure; LC₅₀ values of other species tested were within the range of 4.1–6.2 mg/L PAA. More importantly, the 24‐h no‐observed‐effect concentration (NOEC) ranged from 1.9 to 5.8 mg/L PAA; the NOEC would be considered as the safe range for culturists to investigate the use of PAA. Decreased alkalinity/hardness increased the toxicity of PAA, while a small increase of dissolved organic content had no effect on PAA toxicity. Results of the present study are important information on the safe application of PAA for the aquaculture industry.     

The role of interstitial sites in the Ti3d defect state in the band gap of titania

Titanium dioxide (TiO2) has a number of uses in catalysis, photochemistry, and sensing that are linked to the reducibility of the oxide. Usually, bridging oxygen (Obr) vacancies are assumed to cause the Ti3d defect state in the band gap of rutile TiO2(110). From high-resolution scanning tunneling microscopy and photoelectron spectroscopy measurements, we propose that Ti interstitials in the near-surface region may be largely responsible for the defect state in the band gap. We argue that these donor-specific sites play a key role in and may dictate the ensuing surface chemistry, such as providing the electronic charge required for O2 adsorption and dissociation. Specifically, we identified a second O2 dissociation channel that occurs within the Ti troughs in addition to the O2 dissociation channel in O(br) vacancies. Comprehensive density functional theory calculations support these experimental observations.