Atmospheric deposition, mineralization and leaching of nitrogen in subtropical forested catchments, South China

In recent years, China has conducted considerable research focusing on the emission and effects of sulphur (S) on human health and ecosystems. By contrast, there has been little emphasis on anthropogenic nitrogen (N) so far, even though studies conducted abroad indicate that long-range atmospheric transport of N and ecological effects (e.g. acidification of soil and water) may be significant. The Sino-Norwegian project IMPACTS, launched in 1999, has established monitoring sites at five forest ecosystems in the southern part of PR China to collect comprehensive data on air quality, acidification status and ecological effects. Here we present initial results about N dynamics at two of the IMPACTS sites located near Chongqing and Changsha, including estimation of atmospheric deposition fluxes of NOx and NHx and soil N transformations. Nitrogen deposition is high at both sites when compared with values from Europe and North America (25-38 kg ha(-1) yr(-1)). About 70% of the deposited N comes as NH4, probably derived from agriculture. Leaching of N from soils is high and nearly all as NO3-. Transformation of N to NO3- in soils results in acidification rates that are high compared to rates found elsewhere. Despite considerable leaching of NO3- from the root zone of the soils, little NO3- appears in streamwater. This indicates that N retention or denitrification, both causing acid neutralization, may be important and probably occur in the groundwater and groundwater discharge zones. The soil flux density of mineral N, which is the sum of N deposition and N mineralization, and which is dominated by the N mineralization flux, may be a good indicator for leaching of NO3- in soils. However, this indicator seems site specific probably due to differences in land-use history and current N requirement.

Study on the ecological distribution of alveolar Echinococcus in Hulunbeier Pasture of Inner Mongolia, China

A study on the ecological distribution of alveolar Echinococcus was carried out in the Hulunbeier Pasture of Inner Mongolia, China during 1998 and 1999. Animals examined included wolves (Canis lupus), red foxes (Vulpes vulpes), sand foxes (Vulpes corsac), domestic dogs (Canis familiaris), Microtus brandti, Meriones unguiculatus, Citellus dauricus, Allactaga sibirica, Phodopus sungorus and Ochotona daurica. Three wolves were found to be infected with E. granulosus. Two sand foxes were infected with E. multilocularis. The majority of infections of alveolar echinococcus was found in M. brandti. Based on the structure of metacestodes found in the livers of naturally infected M. brandti, 3 main variants were observed. Type I had small alveolar cysts with thin cyst walls. Type II had a larger cyst with a thick cyst wall. Infection of laboratory mice with the gravid segments isolated from the naturally infected sand foxes led to the formation of mature Type I alveolar metacestodes in the lungs and Type II metacestodes in the livers of infected animals, respectively.

Endovascular treatment of brain-stem arteriovenous malformations: safety and efficacy

Our purpose was to evaluate the safety and efficacy of endovascular treatment of brain-stem arteriovenous malformations (AVMs), reviewing six cases managed in the last 5 years. There were four patients who presented with bleeding, one with a progressive neurological deficit and one with obstructive hydrocephalus. Of the six patients, one showed 100%, one 90%, two 75% and two about 50% angiographic obliteration of the AVM after embolisation; the volume decreased about 75% on average. Five patients had a good outcome and one an acceptable outcome, with a mild postprocedure neurological deficit; none had further bleeding during midterm follow-up. Endovascular management of a brain-stem AVM may be an alternative to treatment such as radiosurgery and microsurgery in selected cases. It may be not as risky as previously thought. Embolisation can reduce the size of the AVM and possibly make it more treatable by radiosurgery and decrease the possibility of radiation injury.

A mixture model-based cluster analysis of DNA microarray gene expression data on Brahman and Brahman composite steers fed high-, medium-, and low-quality diets

The objective of this study is to explore aspects of the statistical analysis of gene expression response at the muscle tissue level to varying levels of energy and protein in the diet. Eleven Brahman and Brahman composite steers (weighing 302 +/- 9.8 kg, on average) were allocated randomly into high- (HIGH), medium- (MED), and low- (LOW) quality forage diets for 27 d. After this period, a biopsy of the longissimus dorsi muscle was taken from each animal and total RNA was extracted to generate the labeled target for microarray experimentation. These targets were hybridized to a complementary DNA (cDNA) microarray of 9,274 probes from cattle muscle and subcutaneous fat cDNA libraries. After edits, 151,904 expression intensity levels of 4,747 genes were analyzed. Emphasis was given to the choice of power transformation of the intensity channel readings and to the consistency of readings within each diet quality group. The statistical approach to isolate differentially expressed genes was based on model-based clustering via a mixture of normal distributions estimated through maximal likelihood. The base-2 logarithm was found to be the optimal power transformation to normalize gene intensity levels. A two-sample t-statistic was defined as a measure of possible differential expression. For each of the three diet contrasts, HIGH vs. LOW, HIGH vs. MED, and MED vs. LOW, three clusters were found, two of which contained more than 94% genes with almost no altered gene expression levels, whereas the third cluster contained the remaining genes with a differential expression. Results from the HIGH vs. LOW contrast identified 27 genes with a greater than 95% posterior probability of belonging to the cluster of differentially expressed genes.

The high value of high-resolution computed tomography in predicting the activity of pulmonary tuberculosis

SETTING

A 2500-bed medical centre in southern Taiwan.

OBJECTIVE

To study the clinical value of high-resolution computed tomography (HRCT) in predicting the activity of pulmonary tuberculosis (TB).

DESIGN

HRCTs were performed prospectively in 148 patients whose chest radiographs (CXRs) showed highly suspicious signs of pulmonary TB, predominantly upper lung field infiltration. The HRCT findings, interpreted independently by a pulmonologist and a radiologist, were used to predict the activity of pulmonary TB.

RESULTS

Pulmonologist-interpreted and radiologist-interpreted HRCTs showed high sensitivity (both 93%), specificity (83 vs. 88%), accuracy (86 vs. 90%), positive predictive values (76 vs. 83%) and negative predictive values (both 95%). Kappa statistic indicates good inter-reader agreement.

CONCLUSION

HRCT has a high value in predicting the activity of pulmonary TB. It is a useful tool in this regard when a patient with suspected pulmonary TB lacks microbiologic proof, when clinical condition makes invasive diagnosis impossible or when a patient has completed anti-tuberculosis treatment with no compatible unequivocal CXR.

Improvement in the performance of automated spike detection using dipole source features for artefact rejection

OBJECTIVE

We evaluated the use of an efficient dipole source algorithm to improve performance of automated spike detection by identifying false detections caused by artefacts.

METHODS

Automated spike detections were acquired from 26 patients undergoing prolonged electroencephalograph (EEG) monitoring. Data from 6 patients were used to develop the method and data from 20 patients were used to test the method. To provide a standard against which to evaluate the results, an electroencephalographer (EEGer) visually categorized all automated detections before the dipole models were calculated for all events. The event categories (as defined by the EEGer) were then combined with properties of the dipole model and features were identified that differentiated spike and artefact detections. The resulting method was then applied to the testing data set.

RESULTS

Residual variance and eccentricity of the dipole models differentiated artefact and spike detections. A separate set of rules defining eye blink artefact was also developed. The combined criteria removed a mean of 53.2% of artefact from the testing data set. Some spike detections (4.3%) were also lost.

CONCLUSIONS

The features of the dipole source of a detected event can be used to differentiate artefacts from spikes. This algorithm is computationally light and could be implemented on-line.

Correlation relationships between physico-chemical properties and gas chromatographic retention index of polychlorinated-dibenzofurans

Correlation relationships between physico-chemical properties including vapor pressures (P), water solubilities (S), Henry's law constants (H(c)), n-octanol-water partition coefficients (K(ow)), sediment-water partition coefficient (K(pw)) and biotic lipid-water partition coefficient (K(bw), bioconcentration factor) of polychlorinated-dibenzofurans (PCDFs) and their gas chromatographic retention indices (GC-RIs) were established. A model equation between GC-RIs (= RI) and these physico-chemical properties (K) of PCDFs was in a form of log K = aRI2 + bRI + c with correlation coefficients (R2) greater than 0.94, except H(c). These equations were derived from six experimental data (five experimental data for log K(bw)) in each physico-chemical properties of PCDFs reported previously. The values of log P, log S, log H(c), log K(ow), log K(pw) and log K(bw) of PCDFs predicted by these equations based on their GC-RIs in the present study derviated from those calculated by the solubility parameters for fate analysis method in a previous study by 0.49, 0.32, 0.11, 0.34, 0.14 and 0.22 log units, respectively.

Heat stress prevents mitochondrial injury in ATP-depleted renal epithelial cells

The events that precipitate cell death and the stress proteins responsible for cytoprotection during ATP depletion remain elusive. We hypothesize that exposure to metabolic inhibitors damages mitochondria, allowing proapoptotic proteins to leak into the cytosol, and suggest that heat stress-induced hsp72 accumulation prevents mitochondrial membrane injury. To test these hypotheses, renal epithelial cells were transiently ATP depleted with sodium cyanide and 2-deoxy-D-glucose in the absence of medium dextrose. Recovery from ATP depletion was associated with the release into the cytosol of cytochrome c and apoptosis-inducing factor (AIF), proapoptotic proteins that localize to the intermitochondrial membrane space. Concomitant with mitochondrial cytochrome c leak, a seven- to eightfold increase in caspase 3 activity was observed. In controls, state III mitochondrial respiration was reduced by 30% after transient exposure to metabolic inhibitors. Prior heat stress preserved mitochondrial ATP production and significantly reduced both cytochrome c release and caspase 3 activation. Despite less cytochrome c release, prior heat stress increased binding between cytochrome c and hsp72. The present study demonstrates that mitochondrial injury accompanies exposure to metabolic inhibitors. By reducing outer mitochondrial membrane injury and by complexing with cytochrome c, hsp72 could inhibit caspase activation and subsequent apoptosis.

Hsp72 expression enhances survival in adenosine triphosphate-depleted renal epithelial cells

Although prior heat stress (HS) inhibits apoptosis in adenosine phosphate (ATP)-depleted renal epithelial cells (REC), the specific stress protein(s) responsible for cytoprotection have not been identified. The present study evaluated the hypothesis that Hsp72, the major inducible member of the Hsp70 family, protects REC against ATP depletion injury. In the presence of isopropyl-beta-D-thiogalactoside (IPTG), a stable line of transfected opossum kidney cells was induced to overexpress human Hsp72 tagged with the flag epitope. Transfected cells from 2 clones that expressed Hsp72 at a level comparable with wild-type cells were subjected to transient heat stress (43 degrees C for 1 hour). To assess the cytoprotective effect of Hsp72, transfected cells were subjected to transient ATP depletion followed by recovery in the presence vs the absence of IPTG. ATP depletion resulted in nuclear chromatin condensation without cell membrane injury (ie, minimal leak of lactate dehydrogenase) and activation of caspase-3, confirming that apoptosis is the major cause of cell death. In both clones cell survival 1-3 days after ATP depletion was significantly improved in the presence of IPTG. Selective overexpression of Hsp72 reproduced nearly 60% of the protective effect on the survival afforded by prior heat stress. In transfected cells subjected to ATP depletion, Hsp72 overexpression significantly inhibited caspase activation. In native renal cells brief ATP depletion markedly induced the expression of native Hsp72, a finding identical to that observed after renal ischemia in vivo. These studies are the first to directly show that Hsp72 per se mediates acquired resistance to ischemic injury in REC.

Effect of loading on the development of nerve fibers around oral implants in the dog mandible

Occlusal forces cause stress which morphologically affects the supporting tissues of implants. The aim of this study was to examine the effects of occlusal forces on the distribution of neurofilament protein (NFP)-positive nerve fibers in the tissue of peri-implant bone. The bilateral 2nd, 3rd and 4th mandibular premolars and the 1st molars were extracted from three mongrel dogs. After 4 months of healing, 4 screw-type implants were inserted in the oral cavity. Three months after insertion, the implants on the molar site were loaded by occlusal forces, while those on the premolar site were unloaded. After a further 3 months, the dogs were sacrificed, and specimens were prepared for immunohistochemical NFP-positive staining by the labeled-streptavidin-biotin method. Many NFP-positive nerve fibers were found in the tissues of the loaded site when compared with the unloaded site. These fibers were localized in both the bone marrow space and in the peri-implant fibrous tissue. They had two types of nerve endings: simple free nerve endings, and nerve endings with tree-like ramifications. The present results suggest that loading by occlusal force causes an increase in the number of NFP-positive nerve fibers, many of which have free nerve endings in the peri-implant tissue. The possible role of these NFP-positive nerve fibers is discussed.

[Effects of Rholida on the free radical metabolism and serum creatine kinase after exercise at plateau]

Objective. To study the effect of Rholida on free radical metabolism and serum creatine kinase CK) after exercise at plateau. Method. After staying at high altitude (4100 m) for 20 d, 40 healthy young men were divided into 4 groups randomly (Rholida, Acetazolamide, Xi' s capsule and control, 10 men each group). And their SOD, MDA, GSH-Px CK, and CK-MB were determined respectively. Before, after taking drugs and after finishing the 5 min-stair-exercise. Result. Before taking drugs and after exercise, MAD GSH-Px, CK, CK-MB, increased as compared with quiet state (P<0.05, P<0.01), but SOD showed no significant chang (P>0.05). After taking drugs for 6 d, those who took Rholida, Acetazolamide and Xi's capsule, their MAD, GSH-Px CK, CK-MB increased after exercise as compared with quiet state (P<0.05). In Rholida group SOD increased and had significant change (P<0.05); but there was no significant change in Acetazolamide, Xi' s capsule group, SOD increased, MDA decreased (P<0.05), CK, CK-MB had no significant change (P>0.05), GSH-Px increased in Xi's group (P<0.05), but not in Acetazolamide group (P>0.05). SOD, GSH-Px increased, MDA, CK-MB decreased in Rholida group after taking drugs and the changes were significant (P<0.01). In Acetazolamide and Xi's capsule group, GSH-Px increased significantly, MDA, CK, CK-MB decreased significantly (P<0.05), but SOD didn't (P>0.05). Conclusion. Rholida, Acetazolamide, Xi's capsule could regulate the disorder of free radical metabolism at plateau and Rholida had advantage over the others.

Differential responses of regional vascular beds to local injection of agmatine in rats

In 66 anaesthetized rats, the effects of local injection of agmatine on femoral, renal, and mesenteric vascular beds were investigated respectively by constant flow perfusion method. The results are as follows. (1) Agmatine (0.1, 0.5, 1 mg/kg) increased the perfusion pressure (PP) of femoral vascular bed in a dose dependent manner. The effect of agmatine (1 mg/kg) was completely blocked by pretreatment with idazoxan (0.5 mg/kg), an antagonist for imidazoline receptors (IR) and alpha(2)-adrenergic receptors (alpha(2)-AR), and yohimbine (1 mg/kg), a selective alpha(2)-AR antagonist. (2) Agmatine also increased the PP of renal vascular bed in a dose-dependent manner, and agmatine at high dose (1 mg/kg) caused a biphasic increase of PP in renal vascular bed. Idazoxan blocked these effects completely, while yohimbine led the agmatine induced effect to a decrease in the PP of renal vascular bed. (3) Agmatine decreased the PP of mesenteric vascular bed in a dose-dependent manner, an effect which was completely blocked by idazoxan, but unaffected by yohimbine. From the results obtained, it is concluded that agmatine differentially affects the vascular tone in the femoral, renal, and mesenteric vascular beds.

Emission of M2X+ cluster ions in thermal ionization mass spectrometry in the presence of graphite

The emission of M2X+ cluster ions in thermal ionization mass spectrometry when graphite is loaded on the heating filaments was studied. The emission model of non-reductive thermal ionization of graphite was preliminarily discussed and factors influencing the thermal emission of M2X+ ions were investigated. The results show that the intensities of M2X+ cluster ions are related to ionic radius and crystal lattice energy, and possibly also to the solvation energies of ions. The intensities of M2Cl+ (M stands for K, Rb, and Cs) cluster ions, the M2Cl+/M+ ratios, and the 37Cl/35Cl ratios determined from M2Cl+ ion measurement usually increase with measurement time. The variation of the 37Cl/35Cl ratios determined from Cs2Cl+ ion measurement is lower than those based on K2Cl+ and Rb2Cl+ ion measurement, indicating the lowest isotopic fractionation.

Sensation seeking correlates of passive auditory P3 to a single stimulus

A single auditory stimulus in a passive ignore condition elicits a P3 potential (passive P3) that shares similar morphology with the classical P3 (P300 or P3b) in the active auditory 'oddball' paradigm. Since the classical P3 is correlated with introversion, anxiety, or sensation seeking, it was hypothesized that the passive P3 is correlated with sensation seeking personality. Therefore, 39 healthy subjects aged from 15 to 57 years and free from depression, were asked to answer Zuckerman's sensation seeking scales (SSS), and undergo an auditory event-related potential procedure with a single stimulus. In all subjects, a clear passive P3 appeared at three midline electrodes that shared similar latency and amplitude to the classical P3. The SSS total and experience seeking subscale scores were positively correlated with N1 amplitude at Fz. In contrast, the SSS total and some subscale scores were negatively correlated with the passive P3 amplitudes at the three electrodes. The sensation seeking personality effects on the passive P3 might be via a cortical inhibition process during memory updating, which are considered to be involved in the classical P3.

Long-term clinical outcome of spontaneous carotid cavernous sinus fistulae supplied by dural branches of the internal carotid artery

We report the long-term clinical outcome of spontaneous carotid cavernous sinus fistulae (CCF) originally supplied by branches arising from the internal carotid artery (Barrow's type B), or type-D lesion that became type B after particulate embolization. A total of 55 patients was included in this study. Their angiography revealed that cortical drainage was absent, and that the arteries supplying the fistulae originated in the dural branches of the internal carotid artery. Thirty-two patients had type-D lesions, which became type-B lesions after obliteration of the external carotid supply by endovascular treatment. The other 23 patients had type-B lesions documented by angiography, and had no embolization. The follow-up period ranged from 8 to 144.5 months. Clinical cure was achieved in 39 patients (70.9%), improvement in eight patients (14.5%), the lesion remained stable in four patients (7.3%), and was aggravated in four patients (7.3%). The number of drainage veins is the only radiographic factor that could predict the outcome. Those patients with single draining veins had a better chance of complete remission. The outcome between the group with original type D lesions after embolization and the group with original type B revealed no statistically significant difference. The time-course to complete cure was significantly shorter in the group with embolization of the external carotid supply. In the four patients whose symptoms were aggravated, embolization was performed, and the result was excellent. The clinical outcome of type-B CCF, or type D converted to type B, is good. Previous external carotid artery embolization can significantly shorten the time to complete cure. Aggressive treatment should be reserved for those who have aggravated symptoms.

c-Src and HSP72 interact in ATP-depleted renal epithelial cells

Disruption of cell contact sites during ischemia contributes to the loss of organ function in acute renal failure. Because prior heat stress protects cell contact sites in ATP-depleted renal epithelial cells in vitro, we hypothesized that heat shock protein 72 (HSP72), the major inducible cytoprotectant in mammalian cells, interacts with protein kinases that regulate cell-cell and cell-matrix interactions. ATP depletion increased the content of Tyr(416) Src, the activated form of this kinase. c-Src activation was associated with an increase in the tyrosine phosphorylation state of beta-catenin, paxillin, and vinculin, three c-Src substrate proteins that localize to and regulate cell contact sites. Prior heat stress inhibited c-Src activation and decreased the degree of tyrosine phosphorylation of all three Src substrates during ATP depletion and/or early recovery. HSP72 coimmunoprecipitated with c-Src only in cells subjected to heat stress. ATP depletion markedly increased the interaction between HSP72 and c-Src, supporting the hypothesis that HSP72 regulates Src kinase activity. These results suggest that alterations in the tyrosine phosphorylation state of proteins located at the cell-cell and cell-matrix interface mediate, at least in part, the functional state of these structures during ATP depletion and may be modulated by interactions between HSP72 and c-Src.

Reconstitution of recombinant chromatin establishes a requirement for histone-tail modifications during chromatin assembly and transcription

The human ISWI-containing factor RSF (remodeling and spacing factor) was found to mediate nucleosome deposition and, in the presence of ATP, generate regularly spaced nucleosome arrays. Using this system, recombinant chromatin was reconstituted with bacterially produced histones. Acetylation of the histone tails was found to play an important role in establishing regularly spaced nucleosome arrays. Recombinant chromatin lacking histone acetylation was impaired in directing transcription. Histone-tail modifications were found to regulate transcription from the recombinant chromatin. Acetylation of the histone tails by p300 was found to increase transcription. Methylation of the histone H3 tail by Suv39H1 was found to repress transcription in an HP1-dependent manner. The effects of histone-tail modifications were observed in nuclear extracts. A highly reconstituted RNA polymerase II transcription system was refractory to the effect imposed by acetylation and methylation.

Stilbenoids from the lianas of Gnetum pendulum

Two stilbenoids, gnetupendin A and B, were isolated from the lianas of Gnetum pendulum C. Y. Cheng, together with four known compounds, resveratrol, isorhapontigenin, shegansu B and beta-daucosterol. Their structures were determined on the basis of analysis of spectral evidence, especially 2D NMR spectroscopic techniques.

Mapping of 12 bovine ribosomal protein genes using a bovine radiation hybrid panel

Twelve bovine ribosomal protein genes, for which sequence data had been acquired from complementary deoxyribonucleic acid (cDNA) clones isolated from a cattle skin cDNA library, were mapped. As ribosomal protein genes are a group of highly conserved house keeping genes, specific primers were designed to span the intron-exon splice sites and to amplify intronic sequences, in order to obtain bovine-specific polymerase chain reaction (PCR) products. Two of 12 ribosomal protein genes were genotyped in this way and the remaining 10 were mapped using additional primers designed from within the intron. Eleven previously unmapped ribosomal protein genes were localized and one previously reported ribosomal protein gene localization was confirmed. The 12 ribosomal protein genes mapped in this study are spread over 10 chromosomes, including the X chromosome. The locations show conservation of comparative map position in cattle and human.

[Molecular candidates for capacitative calcium entry channel]

The emptying of intracellular calcium store generates a putative signal that induces the opening of the store-operated calcium channel (SOC) at the level of the cell membrane, also known as the capacitative calcium entry (CCE), or the calcium release-activated calcium channel (CRAC), which allows entry of calcium into the cells from the extracellular space. Drosophila transient receptor potential (trp) and trp-like(trpl) genes have been identified and reported to code cation channels(TRP and TRPL). The mechanism of coupling between store depletion and channel opening is unknown. Three fundamental mechanisms have been proposed for transmitting the signal from intracellular stores to the plasma membrane: (1) a diffusible message; (2) protein-protein interactions; and (3) vesicle secretion. This review focuses primarily on the recent studies on the TRP homologues, the possible mechanisms and electrophysiological phenotypes of capacitative calcium entry.

[Two new glycosides from Erigeron breviscapus (Vant.) Hand.-Mazz]

OBJECTIVE

To study the chemical constituents from the upground part of Erigeron breviscapus.

METHOD

The compounds were separated and purified by column chromatography with silica gel, and identified by IR, MS, NMR and 2D-NMR.

RESULT

Two new compounds were isolated and identified as 5,4'-dihydroxy flavonod-7-O-beta-D-pyranglycuronate buthyl ester(VI) and 3,5-dimethoxy benzene carbonic acid-4-O-beta-D-pyranglucose(VII).

CONCLUSION

Compounds VI and VII were new compounds.

Molecular cloning and functional identification of (+)-delta-cadinene-8-hydroxylase, a cytochrome P450 mono-oxygenase (CYP706B1) of cotton sesquiterpene biosynthesis

In cotton, gossypol and related sesquiterpene aldehydes are present in the glands of aerial tissues and in epidermal cells of roots. A cytochrome P450 was found to be expressed in aerial tissues of glanded cotton cultivars, but not or at an extremely low level in the aerial tissues of a glandless cultivar. Its cDNA was then isolated from Gossypium arboreum L. After expression in Saccharomyces cerevisiae, the P450 was found to catalyse the hydroxylation of (+)-delta-cadinene, forming 8-hydroxy-(+)-delta-cadinene. This P450 mono-oxygenase has been classified as CYP706B1, and is the first member of the CYP706 family for which a function has been determined. Sesquiterpene aldehydes and CYP706B1 transcripts were detected in roots of both the glanded and glandless cultivars and in aerial tissues of the glanded cultivar. In suspension cultured cells of G. arboreum, elicitors prepared from the phytopathogenic fungus Verticillium dahliae caused a dramatic induction of CYP706B1 expression. The expression pattern of CYP706B1 and the position at which it hydroxylates (+)-delta-cadinene suggest that it catalyses an early step in gossypol biosynthesis. Southern blotting revealed a single copy of CYP706B1 in the genome of G. arboreum. CYP706B1 holds good potential for manipulation of gossypol levels in cottonseed via genetic engineering.

Nitrate-induced genes in tomato roots. Array analysis reveals novel genes that may play a role in nitrogen nutrition

A subtractive tomato (Lycopersicon esculentum) root cDNA library enriched in genes up-regulated by changes in plant mineral status was screened with labeled mRNA from roots of both nitrate-induced and mineral nutrient-deficient (-nitrogen [N], -phosphorus, -potassium [K], -sulfur, -magnesium, -calcium, -iron, -zinc, and -copper) tomato plants. A subset of cDNAs was selected from this library based on mineral nutrient-related changes in expression. Additional cDNAs were selected from a second mineral-deficient tomato root library based on sequence homology to known genes. These selection processes yielded a set of 1,280 mineral nutrition-related cDNAs that were arrayed on nylon membranes for further analysis. These high-density arrays were hybridized with mRNA from tomato plants exposed to nitrate at different time points after N was withheld for 48 h, for plants that were grown on nitrate/ammonium for 5 weeks prior to the withholding of N. One hundred-fifteen genes were found to be up-regulated by nitrate resupply. Among these genes were several previously identified as nitrate responsive, including nitrate transporters, nitrate and nitrite reductase, and metabolic enzymes such as transaldolase, transketolase, malate dehydrogenase, asparagine synthetase, and histidine decarboxylase. We also identified 14 novel nitrate-inducible genes, including: (a) water channels, (b) root phosphate and K(+) transporters, (c) genes potentially involved in transcriptional regulation, (d) stress response genes, and (e) ribosomal protein genes. In addition, both families of nitrate transporters were also found to be inducible by phosphate, K, and iron deficiencies. The identification of these novel nitrate-inducible genes is providing avenues of research that will yield new insights into the molecular basis of plant N nutrition, as well as possible networking between the regulation of N, phosphorus, and K nutrition.

Determination of Enterococcus faecalis groESL full-length sequence and application for species identification

Amplification of the partial Cpn60 (or GroEL) gene segment has been used for identification of many bacteria, including Enterococcus species. To obtain more sequence data from groESL genes of Enterococcus faecalis, the full-length sequence of the E. faecalis groESL genes containing groES (285 bp), spacer (57 bp), and groEL (1,626 bp) was determined. A database search of GenBank revealed that the deduced E. faecalis GroES and GroEL proteins show significant homology to the GroES and GroEL proteins of other bacteria. The GroEL (groEL) of E. faecalis had the highest identity with Streptococcus pneumoniae (81.8% amino acid sequence identity and 73.0% nucleotide sequence identity), followed by Lactococcus zeae, while GroES (groES) had 60.2% (64.6%) identity with Lactobacillus zeae and 58.5% (66.2%) identity with Lactococcus lactis, followed by 57.0% (65.5%) identity with Bacillus subtilis. Based on the groES sequence, an E. faecalis-specific PCR assay was developed, and this PCR assay was positive for all the E. faecalis strains tested. Dot blot hybridization using either groES or groEL as the probe distinguished E. faecalis clearly from other species, indicating that both genes can be used as suitable targets for E. faecalis identification. Moreover, broad-range PCR-restriction fragment length polymorphism of groESL was designed to differentiate eight commonly encountered Enterococcus species. The Enterococcus species of reference strains could be easily differentiated on the basis of restriction patterns produced by HaeIII and RsaI. The DNA-based assays developed in this study provide an alternative to currently used methods of identification for clinically important enterococcal species.