The impact of copper ions on growth, lipid peroxidation, and phenolic compound accumulation and localization in lentil (Lens culinaris Medic.) seedlings

Changes in phenolics (PhC) measured as UV-absorbing compounds (UVAC) and their localization as well as growth, lipid peroxidation (TBARS level), H(2)O(2) and Cu accumulation and other ions content in roots of two lentil cultivars (cv. Krak and cv. Tina) contrasting in Cu sensitivity were examined. The aim of this study was to reveal the importance of PhC in Cu tolerance. During Cu treatment, inhibition of growth and increases in lipid peroxidation in roots of both cultivars were observed, but the effects were more pronounced in cv. Tina (more sensitive) than in cv. Krak (less sensitive). Cu at 0.5 mM caused higher Cu and H(2)O(2) accumulation, but lower K(+) content and UVAC levels in the root tips of cv. Tina. Opposite changes were recorded in cv. Krak. Fluorescence microscopic analyses confirmed greater PhC accumulation in cv. Krak (less sensitive) than in cv. Tina (more sensitive) after Cu treatment and showed that these compounds accumulated particularly in vacuoles and the cell wall. Taken together, these results show that, in spite of the high concentration of Cu-stimulated PhC accumulation in cv. Krak, it was not sufficient to counteract the amount of ROS generated by the metal. The role of PhC in different reactions to Cu stress in lentil roots is discussed.

Effects of antheridial peptides derived from Chara on cell cycle-regulated processes in human and yeast cells

Previous experiments have shown that extracts obtained from maturing male sex organs of Chara tomentosa, containing a low molecular weight peptide (termed antheridial chromatin condensation factor--ACCF) are capable to induce structural and functional effects in root meristems and fern gametophytes. Our present data point to a number of resemblances between the phenotypic characters of antheridial filaments (a.f.) and the properties of ACCF-treated human lymphocytes and HeLa cells; these comprise primarily a number of morphological changes at the nuclear/chromosomal levels. Mitotic chromosomes become shortened and the relative duration of prophase is reduced, while duration of telophase is prolonged. Nucleolar profiles in ACCF-treated HeLa cells become reduced. Significant decrease in mitotic activity was found in human and yeast cells (Schizosaccharomyces pombe). All the above similarities between the "innate" processes within a.f. and those induced by ACCF provide positive evidence for the presence of a highly specific factor that contributes to nuclear re-patterning of cells undergoing morphogenetic transformations before the onset of spermiogenesis.

Extract from maturing antheridia of Chara induces increased condensation of mitotic chromosomes in root meristem cells

Serving as the incubation medium for root meristems of Allium cepa and Melandrium noctiflorum, crude extracts obtained from maturing male sex organs of Chara tomentosa induce: (1) increased condensation (with both shortening and thickening) of prophase, metaphase and anaphase chromosomes, (2) disarrangement of metaphase plates and aberrant segregation of chromosomes during anaphase, and (3) abnormal decondensation of chromosomes at telophase. Numerous resemblances that exist between the natural processes occurring in male sex organs of Chara and root meristem cells from antheridial extract-treated seedlings suggest the existence of a diffusible condensation-promoting factor, responsible for the reorganization of chromatin.

Cell cycle arrest in antheridial extract-treated root meristems of Allium cepa and Melandrium noctiflorum

Previous results have demonstrated that extracts derived from maturing male sex organs of Chara tomentosa are capable of inducing profound structural and functional effects upon M-phase cells in the primary root meristems of Melandrium noctiflorum and Allium cepa. Evident changes produced by a putative factor engaged in morphogenesis of antheridial filaments are manifested by: (1) significant shortening of chromosomes, (2) decreased mitotic indices, and (3) altered proportions estimated for the prophase and telophase transit times. The present image analysis of late G2 phase nuclei in antheridial filaments of C. tomentosa supports the concepts that progressive changes of their functional activities correspond closely to the increasing proportion of condensed chromatin. Cytophotometric measurements of Feulgen-stained cell nuclei in root meristems after a prolonged incubation in antheridial extracts revealed that cells which previously divided asynchronously became preferentially arrested in G1 (M. noctiflorum) and G2 (A. cepa). The stages at which the cells arrest are supposed to counterpart restriction checkpoints that prevent the initiation of DNA synthesis and mitosis. This assumption has been confirmed by autoradiographic studies using 3H-thymidine. In terms of the "Principal Control Points" (PCP) hypothesis, the obtained results suggest that two PCPs regulate G1-->S and G2-->M transition in a nuclear structure-dependent and a species-specific manner. Although in antheridial extract-treated roots of both M. noctiflorum and A. cepa there are only slight changes in the levels of chromatin condensation, the relative proportions of G1- and G2-arrested cells and their nuclear density profiles differ, as compared with the control and carbohydrate-starved plants.

ANTHERIDIAL CHROMATIN CONDENSATION FACTOR FROM MALE SEX ORGANS OF CHARA TOMENTOSA

Incubation of roots (Melandrium noctiflorum) in crude extracts obtained from maturing male sex organs of Chara tomentosa results in supercondensation of mitotic chromosomes. The observed changes, including a number of 'secondary effects', confirm precisely with all those kinds of alterations which are typical of M-phase cells in antheridial filaments during their progression from the proliferative period of development towards terminal differentiation into sperm cells. Biological assays performed with proteinaceous extracts of maturing antheridia indicate that the activity is confined merely to a fraction containing low molecular (4.5 kDa) peptides, termed as ACCF (antheridial chromatin condensation factor). Microchemical tests showed the acidic character of ACCF and its apparent ability to form cross-links with histones and DNA-histone complexes, mediated presumably by disulfide bridges. The characteristic punctate distribution of vesicles within the cytoplasm suggests the internalization of rhodamine-isothiocyanate labelled ACCF (ACCF-TRITC) by endocytosis, implying possible sequestering and nuclear translocation upon release from the endosomal/lysosomal compartment of the cell. Copyright 1998 Academic Press.

Transport of glutathione S-conjugates in the yeasts Saccharomyces cerevisiae

Transport of 2,4-dinitrophenyl-S-glutathione (DNP-SG) and a fluorescent glutathione S-conjugate, bimane-S-glutathione (B-SG) was studied in the baker's yeasts (S. cerevisiae). Both conjugates were exported from the cells; the transport was inhibited by fluoride and vanadate like in mammalian cells. B-SG was also found to be accumulated in the vacuoles. The transport rate of DNP-SG outside the cell was higher in a vacuolar-deficient strain. A significant ATP-dependent uptake of (3H)-DNP-SG by vacuoles was found. These results indicate that S. cerevisiae transport glutathione S-conjugates both outside the cells and into the vacuoles.

Nucleolar patterns in antheridial filaments of mono- and dioecious Chara spp. (Characeae) with different DNA C-values

Using NOR-silver-staining technique, nucleolar arrangements have been studied in antheridial filaments among 5 taxa of Chara with different genome sizes: monoecious Chara vulgaris L., C. fragilis Desv., C. contraria Kütz, and dioecious: Chara aspera Willd., and Chara tomentosa L. It is argued that due to a chain-series of regulatory processes establishing correlations between nucleolar cycles and consecutive cell growth cycles, the diminution of nucleoli observed throughout the development of antheridial filaments is a common and widespread feature of spermatogenesis shared by all the studied species. It is probably a controlling mechanism acting over the morphogenetic reduction of cell dimensions and cessation of mitotic divisions.

Changes in ultrastructure of plasmodesmata during spermatogenesis in Chara vulgaris L

Two types of plasmodesmata are found within an antheridium of Chara vulgaris: open plasmodesmata filled with electron-transparent cytoplasm, and plugged plasmodesmata, filled with an osmiophilic dense substance. Open plasmodesmata occur only between cells synchronized completely in respect of their advancement in cell-cycle progression or differentiation. Plugged plasmodesmata connect different types of cells or cells of the same type at various stages of the cell cycle. Open plasmodesmata may become plugged, and vice versa. These changes are connected with the limitation or extension of synchronization of cellular divisions and differentiation within the groups of cells in the antheridium.