Cytotoxic allelochemicals induce ultrastructural modifications in Cassia tora L. and mitotic changes in Allium cepa L.: a weed versus weed allelopathy approach.

The stress induced by allelochemicals present in stem aqueous extract (SAE) of Nicotiana plumbaginifolia on alterations in growth, ultrastructure on Cassia tora L., and mitotic changes on Allium cepa L. were inspected. Application of SAE at different concentrations (0.5, 1, 2, and 4%) expressively reduced the growth of C. tora in terms of seedling length and dry biomass. Moreover, the ultrastructural variations induced in the epidermis of Cassia leaf (adaxial and abaxial surface) of 15-day-old saplings were analyzed through scanning electron microscopy (SEM). The variations noticed are rupturing and shrinking of cells along epidermis; damaged margins, extensively curled leaf apex along with the appearance of puff-like structures, grooves, and thread-like structures on the leaf surface. The epidermal cells of samples exposed to treatment no longer appear smooth relative to control, besides showing necrosis as well. Upon exposure to different concentrations of extract, A. cepa root tip cells showed aberrations in chromosome arrangement and disparity in the shape of the interphase and prophase nuclei along various phases of mitotic cycle as compared to control. The mitotic index (MI) showed a concentration-dependent decline in onion root tips exposed to SAE. The aberrations appearing frequently were formation of multinucleated cells, sticky metaphase and anaphase with bridges, sticky telophase, disturbed polarity, etc. The results also show the induction of elongated cells, giant cells, and cells with membrane damage by extract treatment. To our knowledge, this is the first gas chromatography-mass spectrometry (GC-MS) analysis of the methanolic extract of N. plumbaginifolia stem. Overall, 62 compounds were reported, covering 99.61% of the entire constituents, which can be considered responsible for the allelopathic suppression of C. tora. The chief component was 4-tert-butylcalix[4]arene with the highest composition of 19.89%, followed by palmitic acid (12.25%), palmitoleic acid (8.23%), precocene 2 (7.53%), isophytyl acetate (4.01%), and betastigmasterol (3.95%).

MorphoGraphX: A platform for quantifying morphogenesis in 4D.

Morphogenesis emerges from complex multiscale interactions between genetic and mechanical processes. To understand these processes, the evolution of cell shape, proliferation and gene expression must be quantified. This quantification is usually performed either in full 3D, which is computationally expensive and technically challenging, or on 2D planar projections, which introduces geometrical artifacts on highly curved organs. Here we present MorphoGraphX ( www.MorphoGraphX.org), a software that bridges this gap by working directly with curved surface images extracted from 3D data. In addition to traditional 3D image analysis, we have developed algorithms to operate on curved surfaces, such as cell segmentation, lineage tracking and fluorescence signal quantification. The software's modular design makes it easy to include existing libraries, or to implement new algorithms. Cell geometries extracted with MorphoGraphX can be exported and used as templates for simulation models, providing a powerful platform to investigate the interactions between shape, genes and growth.

Microscopic evaluation and seasonal variations of anthraquinone glycosides of cultivated Cassia fistula Linn.

In this report, we present the results of the microscopy, seasonal variations and spectrophotometric estimation of hydroxy-anthraquinone glycosides of culitivated Cassia fistula Linn. The total glycoside contents ofthe morphological parts of this species at different stages of growth are also presented. The study shows that anthraquinone glycosides are concentrated in the leaves (1.75%) and flowers (1.58%) at peak flowering. Notable seasonal variations were observed in the cultivated species. Hydroxyanthraquinones reached peak levels druing the months of September (1.08%) and October (2.20%). There was a significant drop (P < 0.05) in glycoside content during most part of the rainy season. It has been established that anthraquinone glycosides, rather than the aglycones, are the active forms and hence an estimation of the total glycoside content of a sample is a reliable indication of biological activity. The advantages of using the natural anthraquinone laxative when the glycoside content is highest are discussed. The study has provided useful information on the best period for harvesting the morphological parts of C. fistula for drug development.

Seasonal variations of hydroxyanthraquinone content of cultivated Cassia spectabilis DC.

Seasonal variations and spectrophotometric estimation of the anthraquinone content of cultivated Cassia spectabilis DC are presented. Concentrations of anthraquinones peaked in the leaves (1.03%) at flowering Significant (P < 0.05) variations in anthraquinone content were observed in the cultivated species. Anthraquinones reached peak levels during the months of September to January (dry season). There was a significant (P < 0.05) drop in anthraquinone content during the rainy season. The diagnostic microscopic features of this little studied species are also described. This study has provided vital information on the best period of harvest and seasonal distribution of anthraquinones in the leaves of the species.