Disease intensity of some tomato viroses in Serbia

In this paper we present the data on the disease intensity of the tomato plants grown in glass and plastic-houses, and in the open field. The infection was caused by the following viruses: Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV), Alfalfa mosaic virus (AMV), Potato virus X (PVX), Potato virus Y (PVY), Tomato black ring virus (TBRV), Tomato ringspot virus (ToRSV), Tomato aspermy virus (TAV), and Cucumber mosaic virus (CMV). These viruses represented most frequent tomato pathogens in Serbia. According to the obtained results, it could be concluded that 92.94% of the tested tomato plants grown in glass and plastic-houses, and 89.82% grown in the open field were infected by one of the above viruses. Most of the plant samples were infected by two or more viruses. The most frequent viruses — tomato pathogens in Serbia were ToMV, PVY and TMV.     

Carbonic anhydrase activity and biomineralization process in embryos, larvae and adult blue mussels Mytilus edulis L.

To decide whether a physiological role can be attributed to enzymatic activity with respect to crystal formation and biomineralization of the first larval shell, carbonic anhydrase (CA) activity was measured in embryos and larvae of the blue mussels Mytilus edulis L. Also, CA activity was determined in the mantle edge and gonads of adult mussels with different shell length and condition index. The intention was to find a possible correlation between CA activity and adult shell calcification, i.e. gonadal maturation. The comparison of CA activity in different developmental stages of mussels and the results of an X-ray diffraction study of biomineralization processes in embryonic and larval shells indicate that CA activity is maximal at the end of several developmental stages. Consequently, the increase in CA activity precedes some physiological changes, i.e. the somatoblast 2d formation and the occurrence of the first calcite and quartz crystals in embryos, shell field formation in the gastrula stage, shell gland and periostracum production in trochophores, and rapid aragonite deposition in larval prodissoconch I and prodissoconch II shells. Furthermore, it was found that in adult mussels CA activity was quite variable and that in the mantle edge it was frequently inversely related to the activity in the gonad. Received: 28 November 1998 / Received in revised form: 30 August 1999 / Accepted: 31 August 1999     

The influence of coumestrol,zearalenone, and genistein administration on insulin receptors and insulin secretion in ovariectomized rats

The influence of phytoestrogens (genistein and coumestrol) and mycoestrogen (zearalenone) on insulin secretion, liver insulin receptors and some aspects of lipid and carbohydrate metabolism were investigated in this study. Ovariectomized rats were injected s.c. with the above mentioned compounds in the amount of 1 mg for three days. Coumestrol and zearalenone caused a significant increase in uterus weight, similar to the effects observed after estrone action, while this effect was not observed after the genistein injection. Blood insulin level was not changed after phyto- or mycoestrogen treatment. However, coumestrol and genistein significantly decreased the binding capacity of liver insulin receptors. These changes corresponded with alterations in glucose and free fatty acids profiles in blood, as well as with glycogen content in liver. The effects observed after genistein and coumestrol injections differed from those noticed in rats treated with zearalenone or estrone. On the basis of these results we conclude that metabolic effects of high doses of coumestrol and genistein in ovariectomized rats are partly mediated by changes in insulin sensitivity of the liver and that the action of plant estrogens on metabolism is, at least to the some degree, independent of their estrogen activity.     

Agrobacterium rhizogenes-mediated transformation and plant regeneration of four Gentiana species

Shoots of micropropagated Gentiana acaulis, G. cruciata, G. lutea, and G. purpurea were inoculated with suspensions of Agrobacterium rhizogenes cells, strains ATCC 15834 or A4M70GUS. Adventitious roots appeared at the sites of inoculation in all 4 species. Root tips were excised and cultured on growth regulator-free media for 2-6 years. They exhibited very high branching and plagiotropism. Spontaneous bud initiation occurred in roots of G. cruciata. Roots of G. lutea, G. acaulis and G. purpurea were cultured on media with high kinetin concentration, which induced the formation of friable callus tissues. Only in G. purpurea were these calluses organogenic. Regenerated shoots of G. cruciata and G. purpurea gave rise to plants, that displayed the typical phenotypes of A. rhizogenes-transformed plants: short internodes and rolled leaves. In the roots of G. acaulis and G. cruciata, transformed with A. rhizogenes A4M70GUS, a positive reaction with X-gluc indicated the activity of β-glucuronidase. The DNA extracted from hairy roots and from the roots of transgenic plants hybridized with the appropriate genomic probes in Southern blotting. This is taken as evidence of the stable genetic transformation in the 4 Gentiana species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sucrose effects on in vitro fruiting and seed production of Centaurium pulchellum

The effect of sucrose on fruiting, seed production, and seed germination of lesser centaury [Centaurium pulchellum (Sw.) Druce] was examined using explants of flowers and flower buds. Sucrose concentrations in the culture medium ranged from 0.003 to 0.3 M. It has been shown that the number of auxiliary buds, capsules dimension, number of viable seeds per capsule and seed dimensions increased with the increase of sucrose concentrations. The highest values were recorded at sucrose concentrations higher than 0.03 M, except for seeds size, which were larger at sucrose concentration ranging from 0.003 to 0.1 M. The germination of in vitro produced seeds was affected by previous culture history: a higher germination percentage was obtained in seeds that were raised from explants originally grown on medium with sucrose concentrations higher than 0.003 M.     

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.     

Intravenous thrombolysis for acute ischemic stroke--our experiences

Intravenous (i.v.) thrombolysis with recombinant tissue plasminogen activator (rt-PA) is the only available pharmacological therapy to improve the outcome of acute ischemic stroke. We compared 71 patients presenting with ischaemic stroke and given intravenous rt-PA (0.9 mg/kg total dose) within 3 h with 71 patients who present to the hospital more than 3 hours after stroke symptom onset. The primary endpoint was the modified Rankin scale (mRS) at 90 days, dichotomised for favourable and unfavourable (score 2-6). Outcome measures were symptomatic intracerebral haemorrhage within 36 h (haemorrhage associated with National Institutes of Health Stroke Scale [NIHSS] > or = 4 points deterioration), and mortality at 3 months. More patients had favourable outcome with the rt-PA-treated group than with the control group (64.79% vs. 22.54%; p = 0.0001). The greater proportion of patients left with minimal or no deficit 90 days after rt-PA treatment, as compared with the control group. In the treated group symptomatic intracranial hemorrhage occurred in 1 patient who recovered to a level of functional independence, and asymptomatic intracranial hemorrhage was observed in 2 patients. Our experience of an acute stroke thrombolysis service shows that we are able to provide this treatment safely and in accordance with established treatment guidelines. We recommend thrombolytic treatment in acute ischemic stroke for selected population.     

Specific sensing of poly G by the aluminum-salophen complex

The Al(III)-salophen complex 1 exhibited strong spectroscopic changes specifically upon addition of polyG and GpG, while double stranded DNA and RNA, and single stranded polyA, polyU and polyC induced negligible spectral changes of 1. Titrations with mono-nucleotides yielded no spectroscopic changes, revealing that there must be at least two consecutive guanines in single stranded oligonucleotide structure for a measurable spectroscopic change of 1. Preliminary results show that 1 has moderate antiproliferative effect on a number of human tumour cell lines.     

Influence of different Sinorhizobium meliloti inocula on abundance of genes involved in nitrogen transformations in the rhizosphere of alfalfa (Medicago sativa L.)

Inoculation of leguminous seeds with selected rhizobial strains is practised in agriculture to ameliorate the plant yield by enhanced root nodulation and nitrogen uptake of the plant. However, effective symbiosis between legumes and rhizobia does not only depend on the capacity of nitrogen fixation but also on the entire nitrogen turnover in the rhizosphere. We investigated the influence of seed inoculation with two indigenous Sinorhizobium meliloti strains exhibiting different efficiency concerning plant growth promotion on nitrogen turnover processes in the rhizosphere during the growth of alfalfa. Quantification of six target genes (bacterial amoA, nirK, nirS, nosZ, nifH and archaeal amoA) within the nitrogen cycle was performed in rhizosphere samples before nodule formation, at bud development and at the late flowering stage. The results clearly demonstrated that effectiveness of rhizobial inocula is related to abundance of nifH genes in the late flowering phase of alfalfa. Moreover, other genes involved in nitrogen turnover had been affected by the inocula, e.g. higher numbers of amoA copies were observed during flowering when the more effective strain had been inoculated. However, the respective gene abundances differed overall to a greater extent between the three plant development stages than between the inoculation variants.