Urban tree root systems and their survival near houses analyzed using ground penetrating radar and sap flow techniques

Root systems of two mature Field maple trees (Acer campestre L.) growing in both shaded and non-shaded sites, on clay soil in an urban environment, were analyzed by ground penetrating radar (GPR), light microscope and sap flow techniques. The ground surface above the root systems was covered by asphalt. However, a small piece of garden existed near the non-shaded tree, and root area of roots growing in this direction increased significantly, due to a presumed increase in available water and nutrients. However, no garden was present near the shaded tree, therefore roots remaining under the asphalt surface did not increase in area in any particular direction. Maximum rooting depth of shaded and exposed trees, as determined by GPR, was approximately 1.4 and 1.7 m, respectively. The trees utilized relatively large amounts of water for transpiration, i.e. 65–140 l per fine summer day and in average 10 m³ per growing season. However, transpiration expressed per root surface area (and/or whole root system enveloping area) was practically the same in both trees, i.e. 1 dm³ m^-2 d^-1 or almost 100 dm³ m^-2 per growing season. These figures represented about 50% of potential evapotranspiration when considering projected crown areas. Increased transpiration under long-term high evaporation demands may cause occasional local drying of soil around roots, associated with soil shrinking in clay, which can be followed by serious damage to buildings.     

Development of a genetic composite map of Vicia faba using F2 populations derived from trisomic plants

 Seven F₂ families of faba bean descendent from plants trisomic for chromosomes 3, 4, 5 and 6 were analyzed for isozyme markers and two of these were also studied for morphological and RAPD markers and seed-protein genes. Linkage analysis revealed 14 linkage groups, 8 of which were unambiguously assigned to specific chromosomes. Several QTLs for seed weight were identified, the most important of which, located on chromosome 6, explained approximately 30% of the total phenotypic variation. Comparison of results from Vicia faba with the maps of the related species Pisum sativum L. and Cicer arietinum L. revealed one possible new case of linkage conservation. A composite linkage analysis based on 42 markers analyzed in this and previous studies, where line Vf 6 was also used as the female parental, allowed the new assignment of previously independent linkage groups and/or markers to specific chromosomes. Thus, the number of linkage groups was reduced to 13, each comprising an increased number of markers. No contradictory results were detected, indicating the suitability of the statistical procedure and methodology used so far in the development of the map of this species. Received: 30 April 1998 / Accepted: 24 August 1998     

Distinct conformers of amyloid beta accumulate in the neocortex of patients with rapidly progressive Alzheimer's disease

Amyloid beta (Aβ) deposition in the neocortex is a major hallmark of Alzheimer''s disease (AD), but the extent of deposition does not readily explain phenotypic diversity and rate of disease progression. The prion strain–like model of disease heterogeneity suggests the existence of different conformers of Aβ. We explored this paradigm using conformation-dependent immunoassay (CDI) for Aβ and conformation-sensitive luminescent conjugated oligothiophenes (LCOs) in AD cases with variable progression rates. Mapping the Aβ conformations in the frontal, occipital, and temporal regions in 20 AD patients with CDI revealed extensive interindividual and anatomical diversity in the structural organization of Aβ with the most significant differences in the temporal cortex of rapidly progressive AD. The fluorescence emission spectra collected in situ from Aβ plaques in the same regions demonstrated considerable diversity of spectral characteristics of two LCOs—quatroformylthiophene acetic acid and heptaformylthiophene acetic acid. Heptaformylthiophene acetic acid detected a wider range of Aβ deposits, and both LCOs revealed distinct spectral attributes of diffuse and cored plaques in the temporal cortex of rapidly and slowly progressive AD and less frequent and discernible differences in the frontal and occipital cortex. These and CDI findings indicate a major conformational diversity of Aβ accumulating in the neocortex, with the most notable differences in temporal cortex of cases with shorter disease duration, and implicate distinct Aβ conformers (strains) in the rapid progression of AD.     

A phosphatase‐centric mechanism drives stress signaling response

Changing environmental cues lead to the adjustment of cellular physiology by phosphorylation signaling networks that typically center around kinases as active effectors and phosphatases as antagonistic elements. Here, we report a signaling mechanism that reverses this principle. Using the hyperosmotic stress response in Saccharomyces cerevisiae as a model system, we find that a phosphatase‐driven mechanism causes induction of phosphorylation. The key activating step that triggers this phospho‐proteomic response is the Endosulfine‐mediated inhibition of protein phosphatase 2A‐Cdc55 (PP2A^Cdc55), while we do not observe concurrent kinase activation. In fact, many of the stress‐induced phosphorylation sites appear to be direct substrates of the phosphatase, rendering PP2A^Cdc55 the main downstream effector of a signaling response that operates in parallel and independent of the well‐established kinase‐centric stress signaling pathways. This response affects multiple cellular processes and is required for stress survival. Our results demonstrate how a phosphatase can assume the role of active downstream effectors during signaling and allow re‐evaluating the impact of phosphatases on shaping the phosphorylome.     

Evaluation of natural antioxidants of Leuzea carthamoides as a result of a screening study of 88 plant extracts from the European Asteraceae and Cichoriaceae

In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC(50) parameter. 29 extracts exhibited IC(50) value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC(50) = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4',5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3', 4'- tetrahydroxyflavanone (eriodictyol) (2), 3',4',5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-beta-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6'-O-acetyl-beta-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.     

A comparison of the therapeutic and reactivating efficacy of newly developed bispyridinium compounds (K206, K269) with currently available oximes against tabun in rats and mice

The potency of newly developed bispyridinium compounds (K206, K269) in reactivating tabun-inhibited acetylcholinesterase and eliminating tabun-induced lethal toxic effects was compared with commonly used oximes (obidoxime, trimedoxime, the oxime HI-6) using in vivo methods. Studies which determined percentage of reactivation of tabun-inhibited blood and tissue AChE in poisoned rats showed that the reactivating efficacy of both newly developed oximes is comparable with obidoxime and trimedoxime in blood but lower than the reactivating potency of trimedoxime and obidoxime in the diaphragm and brain. Nevertheless, the differences in reactivating efficacy of obidoxime, trimedoxime and K206 was not significant while the potency of K269 to reactivate tabun-inhibited acetylcholinesterase was significantly lower. Both newly developed oximes were also found to be relatively efficacious in elimination of the lethal toxic effects in tabun-poisoned mice. Their therapeutic efficacy corresponds to the therapeutic potency of obidoxime. The oxime HI-6, relatively efficacious against soman, did not seem to be an adequately effective oxime in reactivation of tabun-inhibited AChE and to counteract lethal effects of tabun. Both newly developed oximes (K206, K269) are significantly more efficacious in reactivating tabun-inhibited AChE in rats and to eliminate lethal toxic effects of tabun in mice than the oxime HI-6 but their reactivating and therapeutic potency does not prevail over the effectiveness of currently available obidoxime and trimedoxime and, therefore, they are not suitable for their replacement of commonly used oximes for the treatment of acute tabun poisoning.     

Monitoring of dimethyl sulphate-induced N3-methyladenine, N7-methylguanine and O(6)-methylguanine DNA adducts using reversed-phase high performance liquid chromatography and mass spectrometry

This work describes the determination of N3-methyladenine, N7-methylguanine and O(6)-methylguanine adducts in dimethyl sulphate-treated salmon-testes DNA employing reversed-phase high performance liquid chromatography (RP-HPLC) with UV-vis detection, followed by mass-spectrometric verification using electrospray ionisation in positive mode ESI(+). Within validation parameters, accuracy, precision, calibration parameters, limit of detection (LOD) and quantitation (LOQ) as well as stability of standard stock solutions were tested and presented for UV/vis detection. The limit of detection (LOD) was found to be 0.1 ng/mL for N3-methyladenine and 0.2 ng/mL for both N7-methylguanine and O(6)-methylguanine (S/N=3). The limit of quantitation (LOQ) was found to be 0.5 ng/mL for all measured compounds, (S/N=10). Quantitative results were obtained for each substance based on eight-point calibration. Intra- and inter-day precisions were within 1.73-6.96 and 2.26-7.58%, respectively, and correlation coefficients of calibration curves (R(2)) ranged from 0.9992 to 0.9997. Relative proportion of N7-methylguanine was accounted for 61.53+/-2.97% (R.S.D.=4.8), N3-methyladenine for 38.19+/-2.99% (R.S.D.=9.6) and O(6)-methylguanine for 0.29+/-0.02% (R.S.D.=5.1), respectively. The application of the above-mentioned techniques provides a valuable contribution for simultaneous determination of methylated DNA adducts, and may represent a suitable approach for similar monitoring/screening studies.     

Vascular endothelial growth factor in astroglioma stem cell biology and response to therapy

Malignant astrogliomas are among the most aggressive, highly vascular and infiltrating tumours bearing a dismal prognosis, mainly due to their resistance to current radiation treatment and chemotherapy. Efforts to identify and target the mechanisms that underlie astroglioma resistance have recently focused on candidate cancer stem cells, their biological properties, interplay with their local microenvironment or 'niche', and their role in tumour progression and recurrence. Both paracrine and autocrine regulation of astroglioma cell behaviour by locally produced cytokines such as the vascular endothelial growth factor (VEGF) are emerging as key factors that determine astroglioma cell fate. Here, we review these recent rapid advances in astroglioma research, with emphasis on the significance of VEGF in astroglioma stem-like cell biology. Furthermore, we highlight the unique DNA damage checkpoint properties of the CD133-marker-positive astroglioma stem-like cells, discuss their potential involvement in astroglioma radioresistance, and consider the implications of this new knowledge for designing combinatorial, more efficient therapeutic strategies.     

Effect of protein degradation on spot M(r) distribution in 2-D gels--a case study of proteolysis during development of Streptomyces coelicolor cultures

Proteolysis, a regulated biological process, is reflected by protein spot molecular weight distribution in 2-D gel electrophoretograms. Here we report studies of Streptomyces cultures as they undergo two different developmental processes involving proteolysis. Systematic changes in protein molecular weight distribution between the control samples and those with high activity of proteases were demonstrated. The observations were supported by a numerical model of degradation and its influence on the M(r) distribution. Simple statistics could be used to distinguish between normal and degradative 2-D gel electrophoretic patterns.