Genotoxic activity of 1,2,3-triazolyl modified furocoumarins and 2,3-dihydrofurocoumarins.

The furocoumarin backbone is a promising platform for chemical modifications aimed at creating new pharmaceutical agents. However, the high level of biological activity of furocoumarins is associated with a number of negative effects. For example, some of the naturally occurring ones and their derivatives can show genotoxic and mutagenic properties as a result of their forming crosslinks with DNA molecules. Therefore, a particularly important area for the chemical modification of natural furocoumarins is to reduce the negative aspects of their bioactivity. By studying a group of 21 compounds-1,2,3-triazolyl modified derivatives of furocoumarin and peucedanin-using the SOS chromotest, the Ames test, and DNA-comet assays, we revealed modifications that can neutralize the structure's genotoxic properties. Theoretical aspects of the interaction of the compound library were studied using molecular modeling and this identified the leading role of the polyaromatic molecular core that takes part in stacking-interactions with the pi-systems of the nitrogenous bases of DNA.

Cytotoxicity testing of aqueous extract of bitter leaf (Vernonia amygdalina Del) and sniper 1000EC (2,3 dichlorovinyl dimethyl phosphate) using the Alium cepa test.

BACKGROUND: The unrefined nature of the herbal preparations from Vernonia amygdalina (VA) and toxicity potentials of Sniper may both have severe consequences on the biochemical and genetic systems. OBJECTIVES: To assess the microscopic and macroscopic effects of these substances. METHODS: VA leafs and Sniper were prepared and dissolved in distilled water to give different concentrations. Series of baseline tests were carried out to establish concentration range for root growth. Series of twelve onion bulbs of three per series was prepared, with a series of three onion bulbs serving as control. Chromosomal aberrations were statistically analysed using chi- squared test. Root bundle mean length was obtained after 96 hours and EC50 values at 95% confidence interval was determined from a plot of root length against sample concentrations using Microsoft Excel software. RESULTS: Total cytotoxic effect was induced by 2% sniper and 70% VA. EC50 for VA and sniper were 33.07 and 0.346 respectively. The two substances induced chromosomal aberrations and the effect was concentration dependent. CONCLUSION: There are risks of these widely used substances for therapeutic and environmental purposes.

Intra- and intertissular cytomictic interactions in mic-rosporogenesis of mono- and dicotyledonous plants.

A comparative cytological analysis of intra- and intertissular cytomictic interactions in early micro-sporogenesis of mono- and dicotyledonous plants was performed by the example of the two cellular systems - microsporocytes and tapetum. It is found that cytomixis is the component of intratissular interactions mainly. In the tapetum cells cytomixis is notable for structural and temporary taxon specific features. The nuclear migration in microsporocytes is confined mainly to zygotene-pachytene meiotic stages and characterized by a certain synchronism with cytomixis at the tapetum. Intertissular cytomictic interactions (tapetum - microsporocytes) were found in the monocot anthers only. Intertissular interactions are likely to reflect the intensification of competitive relations between the tapetum and microsporocytes for area in the process of anther tissue differentiation. Polyploid tapetum nucleus and syncytia being powerful acceptors are able to compete with microsporocytes and direct the chromatin translocation to their favor. The absence of intertissular interactions in dicots probably reflects a better balance between the processes of differentiation at somatic and generative tissues into microsporangium compared to monocots.

Pressure-volume curves: revisiting the impact of negative turgor during cell collapse by literature review and simulations of cell micromechanics.

The Scholander-Hammel pressure chamber has been used in thousands of papers to measure osmotic pressure, πc , turgor pressure, Pt , and bulk modulus of elasticity, ε, of leaf cells by pressure-volume (PV) curve analysis. PV analysis has been questioned in the past. In this paper we use micromechanical analysis of leaf cells to examine the impact on PV curve analysis of negative turgor in living cells (Pt ). Models predict negative Pt (-0.1 to -1.8 MPa) depending on leaf cell size and shape in agreement with experimental values reported by J. J. Oertli. Modeled PV curves have linear regions even when Pt is quite negative, contrary to the arguments of M.T. Tyree. Negative Pt is totally missed by PV curve analysis and results in large errors in derived πc and Pt but smaller errors in ε. A survey of leaf cell sizes vs habitat (arid, temperate, and rainforest), suggests that the majority of published PV curves result in errors of 0.1-1.8 MPa in derived πc and Pt , whereby the error increases with decreasing cell size. We propose that small cell size in leaves is an ecological adaptation that permits plants to endure negative values of water potential with relatively little water loss.

Characterization of callase (ß-1,3-D-glucanase) activity during microsporogenesis in the sterile anthers of Allium sativum L. and the fertile anthers of A. atropurpureum.

We examined callase activity in anthers of sterile Allium sativum (garlic) and fertile Allium atropurpureum. In A. sativum, a species that produces sterile pollen and propagates only vegetatively, callase was extracted from the thick walls of A. sativum microspore tetrads exhibited maximum activity at pH 4.8, and the corresponding in vivo values ranged from 4.5 to 5.0. Once microspores were released, in vitro callase activity peaked at three distinct pH values, reflecting the presence of three callase isoforms. One isoform, which was previously identified in the tetrad stage, displayed maximum activity at pH 4.8, and the remaining two isoforms, which were novel, were most active at pH 6.0 and 7.3. The corresponding in vivo values ranged from pH 4.75 to 6.0. In contrast, in A. atropurpureum, a sexually propagating species, three callase isoforms, active at pH 4.8-5.2, 6.1, and 7.3, were identified in samples of microsporangia that had released their microspores. The corresponding in vivo value for this plant was 5.9. The callose wall persists around A. sativum meiotic cells, whereas only one callase isoform, with an optimum activity of pH 4.8, is active in the acidic environment of the microsporangium. However, this isoform is degraded when the pH rises to 6.0 and two other callase isoforms, maximally active at pH 6.0 and 7.3, appear. Thus, factors that alter the pH of the microsporangium may indirectly affect the male gametophyte development by modulating the activity of callase and thereby regulating the degradation of the callose wall.

Evaluation of cytotoxicity and genotoxicity of Inula viscosa leaf extracts with Allium test.

I. viscosa has been used for years in folk medicine for its anti-inflammatory, antipyretic, antiseptic, and paper antiphlogistic activities. In this study, cytotoxic and genotoxic effects of I. viscosa leaf extracts on the root meristem cells of Allium cepa have been examined. Onion bulbs were exposed to 2.5 mg/ml, 5 mg/ml, and 10 mg/ml concentrations of the extracts for macroscopic and microscopic analysis. Tap water has been used as a negative control and Ethyl methanesulfonate (EMS) (2 * 10(-2) M) has been used as a positive control. The test concentrations have been determined according to doses which are recommended for use in alternative medicine. There has been statistically significant (P < .05) inhibition of root growth depending on concentration by the extracts when compared with the control groups. All the tested extracts have been observed to have cytotoxic effects on cell division in A. cepa. I. viscosa leaf extract induces the total number of chromosomal aberrations and micronuclei (MNC) formations in A. cepa root tip cells significantly when compared with control groups. Also, this paper shows for the first time the induction of cell death, ghost cells, cells with membrane damage, and binucleated cells by extract treatment. These results suggest the cytotoxic and genotoxic effects of the I. viscosa leaf extracts on A. cepa.

[Isolation of sperm cells of Allium tub rosum Roxb].

Pollen grains of Allium tuberosum Roxb broke and released their content including generative cells using osmotic shock method. In a medium containing 0.05% CaCl2, 0.01% Boric acid, 0.01%KH2PO4, 15%PEG 10% sucrose (710 mOsmol/kg H2O) 86% pollen grains germinated and grew out pollen tubes, which broke after transferred into 6% mannitol solution, and released tube content including generative cell. When pollen grains were cultured in the same medium but adding 0.1% casein, a few generative cells divided into two sperm cells. Stigmas of Allium tuberosum Roxb were pollinated at second day after anthesis and the styles grow 3 h in vivo. Then the styles were cut and cultured in a medium for about 6-8 h, some pollen tubes grew out of the cut end of the style. The cut end of the style was transferred into a solution containing 6% mannitol to burst pollen tubes. Pairs of sperm cells of Allium tuberosum Roxb were released and collected using a micromanipulator.

Aloe L.--a second plant family without (TTTAGGG)n telomeres.

The physical ends of chromosomes are protected and stabilised by telomeres. The sequence of telomeric DNA normally consists of a simple repeating unit that is conserved in many organisms. Most plants examined have been shown to possess Arabidopsis-type telomeres consisting of many repeat copies of the sequence 5'-TTTAGGG-3'. Using fluorescent in situ hybridisation, slot blotting and the asymmetric polymerase chain reaction we demonstrate an absence of Arabidopsis-type telomeres in the genus Aloe (family Asphodelaceae). The only other plant genera so far reported without such telomeres are Allium, Nothoscordum, and Tulbaghia (family Alliaceae). As these genera and Aloe are petaloid monocots in the Asparagales, it is suggested that an absence of Arabidopsis-type telomeres may be characteristic of this related group of plants.