Impact of abscisic acid in overcoming the problem of albinism in horse chestnut androgenic embryos

Horse chestnut (Aesculus hyppocastanum L., Hyppocastanacea) is a relict species with a slow and complex reproductive cycle considered to have horticultural and medical importance. The cycle maybe circumvented via in vitro androgenesis. Androgenesis of horse chestnut was induced in microspores and anther culture on MS media. Some of the horse chestnut androgenic embryos were albinos. Addition of abscisic acid in media (in concentrations of 0.01, 0.1, 0.5, 1, 2, 5, 10, and 20 mg l^?1) with horse chestnut androgenic embryos has circumvented the reproduction cycle barriers. The best results were achieved on medium with the lowest abscisic acid concentration (0.01 mg l^?1) in microspore culture. The microspore culture proved to be a better model system for embryo production and albino embryo reduction than anther culture. Flow cytometry analysis after maturation treatments induced by ABA showed that 88 % of green embryos originating from microspore culture were haploid. However, 50 % of green embryos from anther culture were haploid. The remaining analyzed androgenic embryos, from both types of cultures were diploid.     

Cutting edge: CD8+ T cell priming in the absence of NK cells leads to enhanced memory responses

It is uncertain whether NK cells modulate T cell memory differentiation. By using a genetic model that allows the selective depletion of NK cells, we show in this study that NK cells shape CD8(+) T cell fate by killing recently activated CD8(+) T cells in an NKG2D- and perforin-dependent manner. In the absence of NK cells, the differentiation of CD8(+) T cells is strongly biased toward a central memory T cell phenotype. Although, on a per-cell basis, memory CD8(+) T cells generated in the presence or the absence of NK cells have similar functional features and recall capabilities, NK cell deletion resulted in a significantly higher number of memory Ag-specific CD8(+) T cells, leading to more effective control of tumors carrying model Ags. The enhanced memory responses induced by the transient deletion of NK cells may provide a rational basis for the design of new vaccination strategies.     

Quality of chemically modified hemp fibers

Hemp fibers are very interesting natural material for textile and technical applications now. Applying hemp fibers to the apparel sector requires improved quality fibers. In this paper, hemp fibers were modified with sodium hydroxide solutions (5% and 18% w/v), at room and boiling temperature, for different periods of time, and both under tension and slack, in order to partially extract noncellulosic substances, and separate the fiber bundles. The quality of hemp fibers was characterised by determining their chemical composition, fineness, mechanical and sorption properties. The modified hemp fibers were finer, with lower content of lignin, increased flexibility, and in some cases tensile properties were improved. An original method for evaluation of tensile properties of hemp fibers was developed.     

Comparative study of the antimutagenic potential of Vitamin E in different E. coli strains

The antimutagenic potential of Vitamin E due to its antioxidative properties was studied. The new Escherichia coli K12 assay-system designed in our laboratory was employed in order to detect the antimutagenic potential of Vitamin E and to determine its molecular mechanisms of action. The assay is composed of three tests. In Test A, we examine the influence of the antioxidant on induced oxidative mutagenesis in a repair-proficient strain. Spontaneous mutagenesis is monitored in Test B, which is performed with two mutator strains, one mismatch repair-deficient (mutS) and another deficient in 8-oxo-dGTP-ase activity (mutT). In Test M, a repair-proficient strain and its mismatch repair-deficient counterpart (mutH), both carrying a plasmid with microsatellite sequences, are used to measure the level of microsatellite instability. To examine the antimutagenic potential of Vitamin E we also used the WP2 antimutagenicity test. Protective properties of Vitamin E against oxidative mutagenesis were detected in all tests with the E. coli K12 assay-system as well as in the WP2 antimutagenicity test. This study confirms that mismatch repair is essential for repair of oxidative DNA damage. The results obtained indicate that Vitamin E prevents the formation of DNA adducts by lipid peroxidation products rather than those formed by direct oxidation of DNA bases. Moreover, it can reduce microsatellite instability. After further validation, the new E. coli K12 assay-system can be used to test the antimutagenic potential of antioxidants.     

The Effects of Growth Regulators on Flowering of Chenopodium murale Plants in vitro

In vitro culture of Chenopodium murale L. (ecotype 197) green and herbicide SAN 9789 - treated "white" plants was established and the effects of benzylaminopurine (BAP), indole-3-acetic acid (IAA) and gibberellic acid (GA₃) on growth and flowering were tested. Green plants did not flower on glucose free media, while 17 % of plants flowered on 5 % glucose-containing medium. SAN 9789 (10^–5 M) inhibited growth and flowering. BAP and IAA (0.1 – 5 mg dm^–3) also inhibited growth and flowering of green and "white" plants. GA₃ (10 mg dm^–3) stimulated leaf development in green plants, but had no significant effect on "white" plants, and stimulated flowering of green (41 %) and "white" (33 %) plants.     

The Engineering of a Novel Ligand in gH Confers to HSV an Expanded Tropism Independent of gD Activation by Its Receptors

Herpes simplex virus (HSV) enters cells by means of four essential glycoproteins - gD, gH/gL, gB, activated in a cascade fashion by gD binding to one of its receptors, nectin1 and HVEM. We report that the engineering in gH of a heterologous ligand – a single-chain antibody (scFv) to the cancer-specific HER2 receptor – expands the HSV tropism to cells which express HER2 as the sole receptor. The significance of this finding is twofold. It impacts on our understanding of HSV entry mechanism and the design of retargeted oncolytic-HSVs. Specifically, entry of the recombinant viruses carrying the scFv-HER2–gH chimera into HER2⁺ cells occurred in the absence of gD receptors, or upon deletion of key residues in gD that constitute the nectin1/HVEM binding sites. In essence, the scFv in gH substituted for gD-mediated activation and rendered a functional gD non-essential for entry via HER2. The activation of the gH moiety in the chimera was carried out by the scFv in cis, not in trans as it occurs with wt-gD. With respect to the design of oncolytic-HSVs, previous retargeting strategies were based exclusively on insertion in gD of ligands to cancer-specific receptors. The current findings show that (i) gH accepts a heterologous ligand. The viruses retargeted via gH (ii) do not require the gD-dependent activation, and (iii) replicate and kill cells at high efficiency. Thus, gH represents an additional tool for the design of fully-virulent oncolytic-HSVs retargeted to cancer receptors and detargeted from gD receptors.     

Antioxidative defense organization in retroperitoneal white adipose tissue during acclimation to cold—The involvement of l-arginine/NO pathway

1. Retroperitoneal white adipose tissue (RpWAT) antioxidative defense was investigated in untreated, l-arginine-treated and N^ω-nitro-l-arginine methyl ester (l-NAME)-treated rats kept at 4±1 °C (1, 3, 7, 12, 21 and 45 days) and compared to control rats at 22±1 °C.

2. Cold-acclimation-induced RpWAT weight decrease was accompanied by a decline in glutathione level and increased activity of manganese superoxide dismutase (MnSOD), glutathione S-transferase (GST), catalase, glutathione peroxidase and glutathione reductase at different time-points.

3. l-arginine accelerated RpWAT weight decrease, the increase in MnSOD and GST activities and the prolonged increase of catalase, MnSOD and GST activities. l-NAME delayed cold-induced catalase activity increase and tissue weight decrease. Prolonged l-NAME-treatment had a similar effect on RpWAT as l-arginine.

4. Results suggest the involvement of l-arginine/NO pathway in RpWAT oxidative metabolic augmentation induced by cold-acclimation.

Terpene chemodiversity of relict conifers Picea omorika, Pinus heldreichii, and Pinus peuce, endemic to Balkan

Terpenes are often used as ecological and chemotaxonomic markers of plant species, as well as for estimation of geographic variability. Essential oils of relic and Balkan endemic/subendemic conifers, Picea omorika, Pinus heldreichii, and P. peuce, in central part of Balkan Peninsula (Serbia and Montenegro), on the level of terpene classes and common terpene compounds were investigated. In finding terpene combinations, which could show the best diversity between species and their natural populations, several statistical methods were applied. Apart from the content of different terpene classes (P. omorika has the most abundant O-containing monoterpenes and sesquiterpenes; P. heldreichii and P. peuce have the largest abundance of sesquiterpene and monoterpene hydrocarbons, resp.), the species are clearly separated according to terpene profile with 22 common compounds. But, divergences in their populations were established only in combination of several compounds (specific for each species), and they were found to be the results of geomorphologic, climatic, and genetic factors. We found similarities between investigated species and some taxa from literature with respect to terpene composition, possibly due to hybridization and phylogenetic relations. Obtained results are also important regarding to chemotaxonomy, biogeography, phylogeny, and evolution of these taxa.