Barbara Gabara

Changes in the ultrastructure of chloroplasts and mitochondria and antioxidant enzyme activity in Lycopersicon esculentum Mill. leaves sprayed with acid rain

Abstract The effects of simulated acid rain (AR) on the ultrastructure of chloroplasts and mitochondria as well as the antioxidant defence system were investigated in Lycopersicon esculentum Mill. leaves. Analyses carried out 0.5, 3.0, 24, 48, 72 and 96 h after a single spraying of AR (pH 1.8) indicated alterations in 13% of chloroplasts and 95% of mitochondria, at the end of experiment. Disturbances in the structure of these organelles were accompanied by changes in activities of catalase (CAT), ascorbate peroxidase (APx), superoxide dismutase (SOD), including CuZnSOD, glutathione peroxidase (GSH-Px) and glutathione transferase (GST). AR caused a decrease in GSH-Px and CAT activities starting 24 h after treatment but an increase in SOD and its izoenzyme CuZnSOD activities at 72 and 96 h. On the other hand, GST activity significantly increased at 0.5–3 and after 48–72 h while APx activity increased at all experimental times. These data suggest that high APx and GST activities in L. esculentum were not sufficient to protect mitochondria but they might have been sufficient to prevent ultrastructural damage of chloroplasts.

Use of polyamidoamine dendrimers to engineer BDNF-producing human mesenchymal stem cells

We report the use of polyamidoamine (PAMAM-NH2) dendrimers along with other non-viral vehicles for the in vitro transfection of human bone marrow mesenchymal stem cells (hMSCs) and for engineering MSCs to secrete brain-derived neurotrophic factor (BDNF). Different generations of cationic polyamidoamine dendrimers (generations 3–6) were tested on HEK 293T cells. hMSCs were then transfected with PAMAM-NH2 G4 dendrimers and Lipofectamine 2000, which elicited the expression of GFP reporter in around 6 and 20% of the cells, respectively. Both vehicles were then shown to elicit the expression of BDNF in MSCs from a bicistronic cassette. Non-virally induced neurotrophin expression may be a safe and easy method for adapting autologous stem cells for therapeutic treatment of diseases and neural system injuries.

Characterization of complexes formed by polypropylene imine dendrimers and anti-HIV oligonucleotides

Current anti-HIV therapies are capable of controlling viral infection but do not represent a definitive cure. They rely on the administration of antiretroviral nucleoside analogues, either alone or in combination with vectors. Dendrimers are branched, synthetic polymers with layered architectures, promising non-viral vectors in gene therapy. The aim of the paper was to study the interactions between three anti-HIV antisense oligonucleotides (ODNs): SREV, ANTI TAR, GEM91 and different generation polypropylene imine dendrimers (PPI) by monitoring changes in the fluorescence polarization of fluorescein attached to the ends of the ODNs when increasing concentrations of dendrimers were added. Laser Doppler electrophoresis, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to characterize, respectively, zeta potential, particle size and morphology of dendriplexes formed in different molar ratios. Antisense oligonucleotides interacted with polypropylene imine dendrimers in different molar ratios depending on generation. Zeta potential of dendriplexes varied from (-25 to -21) mV to -5 mV (for PPIG3 and PPIG4 complexes) and to zero (for PPIG2 complexes). The structures presented a polydisperse size from about 50 nm to even 700-800 nm by TEM and about 250 nm by DLS. It means that besides single dendriplexes, aggregates were also present.

Effects of NaCl on the response of Mesembryanthemum crystallinum callus to Botrytis cinerea infection

Callus of the halophyte Mesembryanthemum crystallinum was used to study the effect of NaCl on the response to Botrytis cinerea infection. The fungus easily colonized the callus surface and the intercellular spaces. However, in the NaCl-adapted tissues the incidence of penetration was 67 % lower than in the inoculated control tissue. The modification of the infection pattern found in the salt-adapted callus could be related to metabolic adaptations to salinity. This was manifested by the enhanced antioxidant potential of ascorbate, the up-regulated activities of ascorbate peroxidase, as well as guaiacol and syringaldazine peroxidases together with the increased detoxification capacity of glutathione transferase in the NaCl-adapted callus. The post-inoculation changes in NaCl-adapted and non-adapted calli were roughly similar and supported the prooxidative nature of B. cinerea infection.

The effects of the anthocyanin-rich extract from red cabbage leaves on Allium cepa L. root tip cell ultrastructure

The effect of exogenously applied 250 μM anthocyanin-rich (ATH-rich) extract from red cabbage leaves on the ultrastructure of Allium cepa root meristematic cells was investigated. The tested extract slightly affected mitochondria, endoplasmic reticulum (ER), Golgi apparatus and vacuoles. In the presence of ATH, 62% of mitochondria converted to condensed type. In addition swollen, circular ER cisternae were sporadically observed. In the ATH-treated roots, one third of Golgi structures was characterized by the reduced number of vesicles. Moreover in 54% of vacuoles, the electron-dense granular and circular material appeared. Additionally, in the cytoplasm, the presence of numerous multivesicular bodies (MVB) was noticed. The observed ultrastructural modifications of mitochondria, and presumably also ER, probably resulted from the ability of an ATH to affect mitochondrial respiratory activity. The other changes in A. cepa root meristematic cell ultrastructure were connected with the transport of exogenously applied ATH into vacuoles. It seems that they are transported from the plasmolemma to the vacuole by multivesicular bodies (MVB), and there trapped by anthocyanic vacuolar inclusions (AVIs). However, none of the observed ultrastructural changes seemed to disturb cell functions, therefore the ATH-rich extract from red cabbage leaves may be regarded as cell-friendly and can be safely used as a detoxifying agent against heavy metal poisoning, as it is more and more often postulated.

Effects of chilling on the root cell ultrastructure of two soybean cultivars

Two soybean [Glycine max (L.) Merr.] cultivars: Aldana (more resistant) and Essor (less resistant to low temperature) were subjected to chilling at 5°C for 24 h, and then the ultrastructure of the root meristem cells was investigated. The ultrastructure of control root cells of the tested cultivars differed in the number of condensed mitochondria, plastids with phytoferritin, deformed vacuoles, as well as multivesicular bodies (MB) in cytoplasm and vacuoles. Chilling induced concentric endoplasmic reticulum (ER) arrangement in both soybean cultivars, while the circular Golgi apparatus (GA) occurred only in cv. Essor and MB in the cytoplasm of cv. Aldana cells. Additionally, in cv. Aldana chilling increased the number of condensed mitochondria, MB in vacuoles and multilamellar structures (MS) in cytoplasm whereas in cv. Essor it enlarged the population of plastids with phytoferritin and the number of MB in cytoplasm. After chilling treatment the population of deformed vacuoles with phenolic compounds in the form of electron dense granules increased but the number of multilamellar structures (MS) in the vacuoles of both cultivars decreased. The ultrastructural changes induced by the chilling stress were not lethal but rather adaptive, especially in more resistant cv. Aldana.

Genetic analysis and plastid ultrastructure of three chlorophyll lethal mutants in winter rye (Secale cereale L.)

SUMMARYChlorophyll mutants selected after winter rye self-fertilization were the object of the studies. Genetic analysis of F1 and F2 generations has shown that pink, orange and light violet colours of young seedlings (L 69, L 98, I 10) are determined by three recessive, non-allelic genes: cl1, cl2 and cl3. All three genes are lethal and in the homozygotic state cause the death of the seedlings four weeks after germination. In contrast to plastids of green plants, whose internal membrane system differentiates into grana and intergrana thylakoids, the mutated plastids were characterized by the reduction of this system. Besides the lack of internal membranes (I 10), concentric thylakoids arrangement and their fragmentation to vesicles (L 69), or parallely positioned thylakoids accompanied by aggregation of plastoglobuli (L 98) have been observed. Rudimentary grana have been noticed only in orange seedlings (L 98).

Yellowish—brown changes on leaves of winter rye (Secale cereale L.)

SUMMARYTwo mutants of winter rye (Secale cereale L.) (hs1 and hs2) with yellowish-brown changes on leaves are described. Both forms were characterized by a lower number of tillers, but the heigth of plants and length of ears were similar to those in control plants. In mesophyll cells of these mutants the number of chloroplasts and grana and the chlorophull content were lower than those in dark green plants. Genetic analysis of F1, F2 and backcross generations have proved that the trait of yellowish-brown changes is determined by the same recessive gene. This gene is designated yns after term “yellow necrotic spots”.

Characterization of fibrous compound of Golgi vesicles in tapetal cells ofDelphinium

SummaryIt was shown that Golgi structures abundantly appearing in tapetal cells ofDelphinium Ajacis L. developing anthers, prior to meiocytes meiosis, show a fine fibrous material within their vesicles. At the time of the formation of tapetal cell wall this fibrous component, released by an exocytotic process, is incorporated into the cell wall. The membrane of dictyosomes derived vesicles participates in the development of plasma membrane. Fibrous material appears to be morphologically similar to the fibrils of tapetal cell wall; this cell wall gives a positive reaction for cellulose and pectins, as visible in the light microscope. Moreover, the fibrous and pectinase resistant compound of dictyosomes derived vesicles and the fibrils of cell wall disappear partly after cellulase digestion which proves their cellulosic character. On the other hand pectinase treatment as well as ruthenium red staining suggest associated with cellulose pectins within Golgi vesicles.

The trait of transversal, yellow stripes on leaves of rye (Secale cereale L.)

Abstract The lethal chlorophyll mutant is described in this work. It is characterized by irregular, transversal, yellow stripes of equal width on the leaf blade of seedlings. Those seedlings usually produced 2 leaves (though at times 3 or 4), however they did not propagate and some of them died out by the end of November. The way of inheritance of this trait was defined on the basis of segregation of plants with a normal green colour of leaves (491) and plants with yellow, transversal stripes on leaves (167) in the segregating population. The obtained segregation is close to the theoretical ratio 3:1 which shows that the feature is determined by a recessive gene denoted by the symbol tys (transversal, yellow stripes). The expression of gene tys was observed on the level of chloroplast ultrastructure in the shape of a reduction of the number of thylakoids and grana as well as lesser the net photosynthesis of intensity. Moreover, the tys gene caused a significant decrease of chlorophyll a and b content as well as a + b in leaves of the mutant in comparison with control. The chlorophyll mutant characterized above was first described in this work.