Cytotoxic pentacyclic triterpenes from Combretum nigricans

A new pentacyclic triterpene, 11alpha-acetoxy-20,24-epoxy-25-hydroxy-dammar-3-one (1), has been isolated from the African tree Combretum nigricans, together with the known corresponding diol, 20,24-epoxy-11alpha, 25-dihydroxy-dammar-3-one (2). They are responsible, at least in part, for the cytotoxic activity of the methanolic extract of the plant.     

First results on synchrony between seasonal pattern of pheromone trap captures of cotton bollworm, <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> and appearance of freshly emerged larvae on developing cobs of corn hybrids

Synchrony between development of five corn hybrid varieties of various seasonal growing rates (FAO numbers), seasonal flight pattern of male cotton bollworm, Helicoverpa armigera Hb. (Lepidoptera: Noctuidae), as monitored by pheromone traps, and the subsequent appearance of newly hatched larvae on developing cobs were studied at Mezőhegyes, South-Hungary, in 2003 and 2004. The phenological stages of corn hybrids were evaluated using the Iowa State University Scale (R₁–R₅), the flight of male moths was monitored by large capacity, funnel type of pheromone traps and the appearance of freshly hatched larvae on developing cobs were counted by visual inspection. The synchrony between the flight peak of male moths and the peak apperance of L₁ larvae on cobs was investigated by cross-correlation. In 2003 (average daily temperatures 20.7°C, average daily relative humidity 59.9% for the period of 4–18 July) “DK 391”, “DK 443” and “Maraton” hybrid varieties already reached silking stage (R₁) by the time when pheromone traps indicated a peak, at 7 July (peak capture at 3-day intervals 755.5 males/traps). The number of L₁ larvae peaked on developing cobs of these varieties also at 7 July (7.0, 4.0 and 3.8 larvae/50 cobs, respectively). The synchrony between the flight peak of male moths and the peak appearance of L₁ larvae on cobs was proven (LAG = 0). A rather similar trend was observed in “Vilma” hybrid variety: it reached R₁ stage at 7 July, and L₁ larvae appeared only a few days later (11 July, 3.8 larvae/50 cobs) (LAG = −1). However, “Maxima” hybrid variety reached R₁ stage 1 week later (14 July) than the time of peak captures. Here L₁ larvae peaked as late as at 18 July (0.8 larvae/50 cobs), i.e., only after the cob had reached R₁ stage (LAG = −3). A reverse order of dates of R₁ stage and peak capture was observed in “Maxima” in 2004 (average daily temperatures; 22.5°C, average daily relative humidities 72.6% for the period of 15 July–6 August): it reached R₁ stage at 19 July, while peak trap captures were recorded at 6 August (peak capture at 3-day intervals 20.5 males/traps). L₁ larvae were found in the highest numbers on 2 August (1.5 larvae/50 cobs), practically in synchrony with peak caputres (LAG = 0). “Káma” reached R₁ stage in 16 July, and L₁ larvae peaked at 2 August (1.3 larvae/50 cobs) (LAG = 0). On the rest of the corn varieties larvae were found only in too numbers for performing statistical analysis. We conclude that in order to predict the appearance of L₁ larvae, the phenological stage of the corn variety and the seasonal flight pattern of moths, as measured by large capacity pheromone traps, should be considered in combination. If the corn variety already reached R₁ stage, L₁ larvae appear on cobs as early as the time of peak flight of moths. However, no young larvae appear on cobs despite of high trap captures, until the corn reaches the R₁ stage. These findings are discussed in the view of specifying optimal timing of a pesticide application.     

Segmentation of 3D images of plant tissues at multiple scales using the level set method

Background

Developmental biology has made great strides in recent years towards the quantification of cellular properties during development. This requires tissues to be imaged and segmented to generate computerised versions that can be easily analysed. In this context, one of the principal technical challenges remains the faithful detection of cellular contours, principally due to variations in image intensity throughout the tissue. Watershed segmentation methods are especially vulnerable to these variations, generating multiple errors due notably to the incorrect detection of the outer surface of the tissue.

Results

We use the level set method (LSM) to improve the accuracy of the watershed segmentation in different ways. First, we detect the outer surface of the tissue, reducing the impact of low and variable contrast at the surface during imaging. Second, we demonstrate a new edge function for a level set, based on second order derivatives of the image, to segment individual cells. Finally, we also show that the LSM can be used to segment nuclei within the tissue.

Conclusion

The watershed segmentation of the outer cell layer is demonstrably improved when coupled with the LSM-based surface detection step. The tool can also be used to improve watershed segmentation at cell-scale, as well as to segment nuclei within a tissue. The improved segmentation increases the quality of analysis, and the surface detected by our algorithm may be used to calculate local curvature or adapted for other uses, such as mathematical simulations.

     

Protection of originality of Tokaji Aszú: amines and organic acids in botrytized wines by high-performance liquid chromatography

Amine and organic acid composition of Aszú wines from the Tokaj region of Hungary, nonbotrytized Hungarian wines from different regions, and foreign botrytized wines were analyzed by high-performance liquid chromatography. Hungarian and foreign wines (36 Hungarian and seven foreign botrytized wines) were compared in different ways by calculation of ratios of given amine compounds, analyses of variance, principal component, and discriminant analysis. In wines, putrescine and in some samples 3-methyl-butylamine and/or phenyl ethylamine were found in remarkable concentrations, while in botrytized wines four other amines were verified in high concentration. Good separation between Aszú and foreign botrytized wines was found by calculation of the amine component's ratio. The first two principal components of the principal component analysis accounted for 77 and 84% of the total variance in the data of amines and acids, respectively. The component scores of samples grouped according to Aszú, foreign botrytized, and nonbotrytized wines. Linear discriminant analysis was used for differentiation of Aszú, foreign botrytized, and normal wines. Using nine amines and two acids as variables, the correct classification was 97.6%. On the basis of results, an objective evaluation method can be elaborated for quality control in order to protect the authenticity and origin of wine specialties made from botrytized grapes.     

Bioactivity-guided fractionation for the butyrylcholinesterase inhibitory activity of furanocoumarins from Angelica archangelica L. roots and fruits

Isolation and identification of the inhibitors of butyrylcholinesterase (BChE), obtained from the extracts of roots and fruits of Angelica archangelica L., are reported. Our results confirmed the weak inhibitory effect of Angelica roots on acetylcholinesterase activity. BChE inhibition was much more pronounced at a concentration of 100 μg/mL for hexane extracts and attained a higher rate than 50%. The TLC bioautography guided fractionation and spectroscopic analysis led to the isolation and identification of imperatorin from the fruit's hexane extract and of heraclenol-2'-O-angelate from the root's hexane extract. Both compounds showed significant BChE inhibition activity with IC(50) = 14.4 ± 3.2 μM and IC(50) = 7.5 ± 1.8 μM, respectively. Only C8-substituted and C5-unsubstituted furanocoumarins were active, which could supply information about the initial structures of specific BChE inhibitors.     

The composite genome of the legume symbiont Sinorhizobium meliloti

The scarcity of usable nitrogen frequently limits plant growth. A tight metabolic association with rhizobial bacteria allows legumes to obtain nitrogen compounds by bacterial reduction of dinitrogen (N2) to ammonium (NH4+). We present here the annotated DNA sequence of the alpha-proteobacterium Sinorhizobium meliloti, the symbiont of alfalfa. The tripartite 6.7-megabase (Mb) genome comprises a 3.65-Mb chromosome, and 1.35-Mb pSymA and 1.68-Mb pSymB megaplasmids. Genome sequence analysis indicates that all three elements contribute, in varying degrees, to symbiosis and reveals how this genome may have emerged during evolution. The genome sequence will be useful in understanding the dynamics of interkingdom associations and of life in soil environments.     

Emerging coherence in a population of chemical oscillators

Coherence of interacting oscillating entities has importance in biological, chemical, and physical systems. We report experiments on populations of chemical oscillators and verify a 25-year-old theory of Kuramoto that predicts that global coupling in a set of smooth limit-cycle oscillators with different frequencies produces a phase transition in which some of the elements synchronize. Both the critical point and the predicted dependence of order on coupling are seen in the experiments. We extend the studies both to relaxation and to chaotic oscillators and characterize the quantitative similarities and differences among the types of systems.