Microarray Analysis of Late Response to Boron Toxicity in Barley (Hordeum vulgare L.) Leaves

DNA microarrays, being high-density and high-throughput, allow quantitative analyses of thousands of genes and their expression patterns in parallel. In this study, Barley1 GereChip was used to investigate transcriptome changes associated with boron (B) toxicity in a sensitive barley cultivar (Hordeum vulgare L. cv. Hamidye). Eight-day-old aseptically grown seedlings were subjected to 5 or 10 mM boric acid (B(OH)(3)) treatments for 5 days and expression profiles were determined with DNA microarrays using total RNA from leaf tissues. Among the 22,840 transcripts - each represented with a probe set on the GeneChip - 19,424 probe sets showed intensity values greater than 20(th) percentile in at least one of the hybridizations. Compared to control (10 mu M B(OH)(3)), 5 mM B(OH)(3) treatment resulted in differential expression of 168 genes at least by twofold. Moreover, 10 mM B(OH)(3) treatment resulted in at least twofold induction or reduction in expression of 312 transcripts. Among these genes, 37 and 61 exhibited significantly (P <0.05) altered levels of expression under 5 and 10 mM B(OH)(3) treatments, respectively. Differentially expressed genes were characterized using expression-based clustering and HarvEST:Barley. Investigations of expression profiles revealed that B toxicity results in global changes in the barley transcriptome and networks of signaling or molecular responses. A noticeable feature of response to 8 was that it is highly interconnected with responses to various environmental stresses. Additionally, induction of jasmonic acid related genes was found to be an important late response to B toxicity. Determination of responsive genes will shed light on successive studies aiming to elucidate molecular mechanism of B toxicity or tolerance. To the best of our knowledge, this is the first report on global expression analysis of barley seedlings under B toxicity

Anatomy of a microearthquake sequence on an active normal fault

The analysis of similar earthquakes, such as events in a seismic sequence, is an effective tool with which to monitor and study source processes and to understand the mechanical and dynamic states of active fault systems. We are observing seismicity that is primarily concentrated in very limited regions along the 1980 Irpinia earthquake fault zone in Southern Italy, which is a complex system characterised by extensional stress regime. These zones of weakness produce repeated earthquakes and swarm-like microearthquake sequences, which are concentrated in a few specific zones of the fault system. In this study, we focused on a sequence that occurred along the main fault segment of the 1980 Irpinia earthquake to understand its characteristics and its relation to the loading-unloading mechanisms of the fault system

Scattering and anelastic attenuation of seismic energy in the vicinity of north anatolian fault zone, eastern Turkey

Erzincan basin, eastern Turkey, is seismically very active pull-apart basin and developed in between the eastern segments of the north anatolian fault zone. A study of the regional and site attenuation of seismic waves of earthquakes in this area will contribute in predicting earthquake generated ground-motion and becomes vital in making decisions for earthquake regulations and building codes, especially for the cities on the north anatolian fault zone

Frequency-dependent attenuation of S and coda waves in Erzincan region (Turkey)

The attenuation structure of the Erzincan region is studied using the single scattering model of the coda wave generation and coda normalization method for S waves. We have determined the seismic quality factors Q(s)(f) (for S waves) and Q(c)(f) (for coda waves) as a function of frequency for the frequency range 1.5-24 Hz. The quality factors were derived for 161 seismograms that were registered in a 7-day period after the 13 March 1992 Erzincan earthquake (M(s) = 6.8). Digital recordings from six stations at epicentral distances ranging from 5 to 40 km were used, Frequency-dependent attenuation of s waves according to Q(s)(f) = Q(o)fn in the crust beneath Erzincan was obtained as Q(s)(f) = 35f(0.83) by analysing seismograms of 161 local earthquakes which were selected on the basis of good signal to noise ratios, Coda Q values were calculated from the amplitude decay rate of the S-wave coda in seven frequency bands from 1.5 to 24 Hz. In order to investigate a possible lapse time dependence of the estimated coda Q, we have carried out the analysis of each seismogram using four coda lengths which correspond to four different lapse times 20, 30, 40, 50 s measured from the origin time of the earthquake, Q(c) averages about 46 and 766 at 1.5 Hz and 24 Hz, respectively, at 20 s lapse time and has a frequency dependence of the form Q(c) = 29f(1.03), For large lapse time data, t(c) = 50 s, Q(c)(f) was found to vary from 84 at 1.5 Hz to 783 at 24 Hz with the degree of the frequency dependence, n = 0.81

Site attenuation and source parameters on the North Anatolian Fault zone, eastern Turkey estimated from the aftershocks of 13 March 1992 Erzincan earthquake

Site attenuation and source characteristics of 45 aftershocks of the 13 March 1992 Erzincan, eastern Turkey earthquake have been determined from SH-wave spectra using a least-squares best-fit method. Although the most of the seismograms were recorded on the ophiolitic rock sites and the average regional attenuation correction of Q(s)(f) = 35 f(0.83) was applied, the high fall-off rates gamma ranging between 3.0 and 4.5 beyond the corner frequencies of 8-13 Hz were observed on the SH spectra. The site attenuation value, kappa, has been calculated from the slope of the high frequency part of the SH spectra. It was found that kappa varied in the range of 0.0124-0.0364 s and the average was 0.0246 s with a standard deviation of 0.0047 s. The high fall-off rates of observed spectra have decreased considerably as a result of site attenuation corrections and converged to an average value of 2.3. We concluded that the high fall-off rates of SH wave spectra are mainly controlled by highly deformed Miocene ophiolitic formations which covers a wide area in the North Anatolian Fault zone in the vicinity of Erzincan region. Using the spectra that were corrected for regional and site attenuation, and assuming a Brune's source model; seismic moment, source radius, and stress-drops of the aftershocks were computed. We found that stress-drops for some of the aftershocks in Erzincan area have slightly decreased after removal of site attenuation over SH wave observed spectra

Effect of salinity on antioxidant responses of chickpea seedlings

The changes in the activity of antioxidant enzymes, like superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase, and growth parameters such as length, fresh and dry weight, proline and H2O2 contents, chlorophyll fluorescence (Fv/Fm), quantum yield of PSII and the rate of lipid peroxidation in terms of malondialdehyde in leaf and root tissues of a chickpea cultivar (Cicer arietinum L. cv. Gokc,e)under salt treatment were investigated. Plants were subjected to 0.1, 0.2 and 0.5 M NaCl treatments for 2 and 4 days. Compared to controls, salinity resulted in the reduction of length and of the fresh and dry weights of shoot and root tissues. Salinity caused significant ( P < 0.05) changes in proline and MDA levels in leaf tissue. In general, a dose-dependent decrease was observed in H2O2 content, Fv/Fm and quantum yield of photosynthesis under salt stress. Leaf tissue extracts exhibited three activity bands, of which the higher band was identified as MnSOD and the others as FeSOD and Cu/ZnSOD. A significant enhancement was detected in the activities of Cu/ZnSOD and MnSOD isozymes in both tissues. APX and GR activities exhibited significant increases ( P < 0.05) in leaf tissue under all stress treatments, whereas no significant change was observed in root tissue. The activity of CAT was significantly increased under 0.5 M NaCl stress in root tissue, while its activity was decreased in leaf tissue under 0.5 MNaCl stress for 4 days. These results suggest that CAT and SOD activities play an essential protective role against salt stress in chickpea seedlings

Site amplification of S-waves in Bursa City and its vicinity, Northwestern Turkey: comparison of different approaches

Microearthquake recordings of local events have been used to quantify the site effects in the vicinity of Bursa City, northwest Turkey. Since the city is located near the southwest branch of the western extension of the North Anatolian Fault (NAF) zone, the importance of the seismic hazard in the region becomes progressively more important. The accelerograms of 69 earthquakes that were recorded on different geologic units, massive limestone, slope deposit and Quaternary sediment were analyzed to estimate the response of the recording sites. Site amplification functions were obtained by using three different approaches (standard spectral ratio, SSR; horizontal to vertical, H/V ratio and generalized inversion method, GIM) and the differences between the methods were also evaluated. We found large discrepancies between the SSR and H/V ratio methods, specifically; the former yields almost three times higher amplitudes than those obtained in the latter approach. Station located within the Bursa Quaternary basin (SCKR) is characterized by the largest estimates of the amplification amplitudes (8.0, 4.5 and 4.0 for SSR, H/V ratio and GIM, respectively) in all the three methods. On the other hand, stations located on deep limestone geological unit (SIGD and SKAY) show the least amplification level, ranging between 1.0 and 1.6. Three methods are able to identify resonant frequencies of the sites, although the absolute amplitudes of the amplification function are obtained different from each method