Different patterns of regulation for the copper and cadmium metallothioneins of the ectomycorrhizal fungus Hebeloma cylindrosporum

Metallothioneins (MTs) are small cysteine-rich peptides involved in metal homeostasis and detoxification. We have characterized two MT genes, HcMT1 and HcMT2, from the ectomycorrhizal fungus Hebeloma cylindrosporum in this study. Expression of HcMT1 and HcMT2 in H. cylindrosporum under metal stress conditions was studied by competitive reverse transcription-PCR analysis. The full-length cDNAs were used to perform functional complementation in mutant strains of Saccharomyces cerevisiae. As revealed by heterologous complementation assays in yeast, HcMT1 and HcMT2 each encode a functional polypeptide capable of conferring increased tolerance against Cd and Cu, respectively. The expression levels of HcMT1 were observed to be at their maximum at 24 h, and they increased as a function of Cu concentration. HcMT2 was also induced by Cu, but the expression levels were lower than those for HcMT1. The mRNA accumulation of HcMT1 was not influenced by Cd, whereas Cd induced the transcription of HcMT2. Zn, Pb, and Ni did not affect the transcription of HcMT1 or of HcMT2. Southern blot analysis revealed that both of these genes are present as a single copy in H. cylindrosporum. While the promoters of both HcMT1 and HcMT2 contained the standard stress response elements implicated in the metal response, the numbers and varieties of potential regulatory elements were different in these promoters. These results show that ectomycorrhizal fungi encode different MTs and that each of them has a particular pattern of expression, suggesting that they play critical specific roles in improving the survival and growth of ectomycorrhizal trees in ecosystems contaminated by heavy metals.

Sister kinetochore recapture in fission yeast occurs by two distinct mechanisms, both requiring Dam1 and Klp2

In eukaryotic cells, proper formation of the spindle is necessary for successful cell division. We have studied chromosome recapture in the fission yeast Schizosaccharomyces pombe. We show by live cell analysis that lost kinetochores interact laterally with intranuclear microtubules (INMs) and that both microtubule depolymerization (end-on pulling) and minus-end-directed movement (microtubule sliding) contribute to chromosome retrieval to the spindle pole body (SPB). We find that the minus-end-directed motor Klp2 colocalizes with the kinetochore during its transport to the SPB and contributes to the effectiveness of retrieval by affecting both end-on pulling and lateral sliding. Furthermore, we provide in vivo evidence that Dam1, a component of the DASH complex, also colocalizes with the kinetochore during its transport and is essential for its retrieval by either of these mechanisms. Finally, we find that the position of the unattached kinetochore correlates with the size and orientation of the INMs, suggesting that chromosome recapture may not be a random process.

Dynein participates in chromosome segregation in fission yeast

BACKGROUND INFORMATION

In eukaryotic cells, proper formation of the spindle is necessary for successful cell division. For faithful segregation of sister chromatids, each sister kinetochore must attach to microtubules that extend to opposite poles (chromosome bi-orientation). At the metaphase-anaphase transition, cohesion between sister chromatids is removed, and each sister chromatid is pulled to opposite poles of the cell by microtubule-dependent forces.

RESULTS

We have studied the role of the minus-end-directed motor protein dynein by analysing kinetochore dynamics in fission yeast cells deleted for the dynein heavy chain (Dhc1) or the light chain (Dlc1). In these mutants, we found an increased frequency of cells showing defects in chromosome segregation, which leads to the appearance of lagging chromosomes and an increased rate of chromosome loss. By following simultaneously kinetochore dynamics and localization of the checkpoint protein Mad2, we provide evidence that dynein function is not necessary for spindle-assembly checkpoint inactivation. Instead, we have demonstrated that loss of dynein function alters chromosome segregation and activates the Mad2-dependent spindle-assembly checkpoint.

CONCLUSIONS

These results show an unexpected role for dynein in the control of chromosome segregation in fission yeast, most probably operating during the process of bi-orientation during early mitosis.

Chromosomal rearrangements in wheat: their types and distribution

Four hundred and sixty polyploid wheat accessions and 39 triticale forms from 37 countries of Europe, Asia, and USA were scored by C-banding for the presence of translocations. Chromosomal rearrangements were detected in 70 of 208 accessions of tetraploid wheat, 69 of 252 accessions of hexaploid wheat, and 3 of 39 triticale forms. Altogether, 58 types of major chromosomal rearrangements were identified in the studied material; they are discussed relative to 11 additional translocation types described by other authors. Six chromosome modifications of unknown origin were also observed. Among all chromosomal aberrations identified in wheat, single translocations were the most frequent type (39), followed by multiple rearrangements (9 types), pericentric inversions (9 types), and paracentric inversions (3 types). According to C-banding analyses, the breakpoints were located at or near the centromere in 60 rearranged chromosomes, while in 52 cases they were in interstitial chromosome regions. In the latter case, translocation breakpoints were often located at the border of C-bands and the euchromatin region or between two adjacent C-bands; some of these regions seem to be translocation "hotspots". Our results and data published by other authors indicate that the B-genome chromosomes are involved in translocations most frequently, followed by the A- and D-genome chromosomes; individual chromosomes also differ in the frequencies of translocations. Most translocations were detected in 1 or 2 accessions, and only 11 variants showed relatively high frequencies or were detected in wheat varieties of different origins or from different species. High frequencies of some translocations with a very restricted distribution could be due to a "bottleneck effect". Other types seem to occur independently and their broad distribution can result from selective advantages of rearranged genotypes in diverse environmental conditions. We found significant geographic variation in the spectra and frequencies of translocation in wheat: the highest proportions of rearranged genotypes were found in Central Asia, the Middle East, Northern Africa, and France. A low proportion of aberrant genotypes was characteristic of tetraploid wheat from Transcaucasia and hexaploid wheat from Middle Asia and Eastern Europe.

Esophageal capsule endoscopy in patients with suspected esophageal disease: double blinded comparison with esophagogastroduodenoscopy and assessment of interobserver variability

BACKGROUND AND STUDY AIMS

The study aim was to compare the diagnostic yield of capsule endoscopy and esophagogastroduodenoscopy (EGD) in patients with suspected esophageal disease. Secondary aims were to assess interobserver variability of capsule endoscopy readings and safety.

PATIENTS AND METHODS

In total, 98 patients (53 men, 53 +/- 13 years) with an indication for EGD were included. The patient population was artificially enriched to include two thirds of patients with abnormal esophageal findings at EGD, which was followed by capsule endoscopy. Capsule recordings were blindly read by three endoscopists, one from the center that recruited the patient and two from the other center. Study outcomes were the findings described on EGD and capsule endoscopy, agreement between EGD and capsule endoscopy for findings, quality of the capsule recording, and interobserver agreement for capsule endoscopy quality and findings.

RESULTS

EGD was normal in 34 patients and showed esophageal findings in 62 (esophagitis 28, hiatus hernia 21, varices 21, Barrett's esophagus 11, others 7). Average esophageal transit time of the capsule was 361 +/- 393 seconds. Capsule endoscopy was normal in 36 patients but detected esophagitis in 23, hiatus hernia in 0, varices in 23, Barrett's esophagus in 18, and others in 4. The positive predictive value of capsule endoscopy was 80.0 % and the negative predictive value was 61.1 %. Overall agreement per patient was moderate between EGD and capsule endoscopy for the per-patient (kappa = 0.42) and per-findings (kappa = 0.40) analyses. Interobserver agreement between capsule endoscopy readings was moderate for findings (kappa = 0.39) and quality assessment (kappa = 0.24). No adverse event was observed after either EGD or capsule endoscopy.

CONCLUSION

In this study, despite artificial prevalence enrichment, capsule endoscopy showed a moderate sensitivity and specificity in the detection of esophageal diseases.

Double-balloon colonoscopy after failed conventional colonoscopy: a pilot series with a new instrument

BACKGROUND AND STUDY AIMS

The endoscopes that were developed for double-balloon enteroscopy have been successfully used in cases of failed colonoscopy. This study was a pilot series in which a new colonoscope was tested that utilized this double-balloon principle.

PATIENTS AND METHODS

A total of 29 patients (5 men, 24 women; mean age 54 years) in whom conventional colonoscopy had failed were included in this study. Both the failed colonoscopy and the double-balloon colonoscopy procedures were performed under general anesthesia, the usual practice in France. A prototype instrument (working length 152 cm, diameter 9.4 mm) designed to incorporate the principles of double-balloon enteroscopy was used. The completeness of colonoscopy was assessed according to conventional criteria by the achievement of a stable position in the cecum. The indicatons for the procedure, the time to reach the cecum, the need for fluoroscopic control, and adverse events were recorded.

RESULTS

The previous colonoscopy failed due adhesions (n = 16), or to long or fixed loops (n = 13). Complete colonoscopy using the balloon method was achieved in 28/29 patients, taking an average time of 18 +/- 14 minutes; a long sigmoid loop limited the examination to the left flexure in one patient. Balloon colonoscopy using double-balloon methodology was used in 24 patients and the instrument was used without an overtube (i. e. using a single-balloon technique) in five patients. Fluoroscopy was used in 16 patients to monitor endoscope progression. No complications were reported.

CONCLUSIONS

Double-balloon colonoscopy enables full colonic examination in almost all patients with a previous incomplete colonoscopy. The overtube should be used in most cases. The use of fluoroscopic assessment of scope progression could be reduced further with increasing experience.

Concentration of soluble and nonsoluble zinc-based impurities by unidirectional freezing: basis for a method of sludges treatment

Heavy metals are known to be significant pollutants in sludges produced by wastewater treatment. A newtechnique to make the metallic contaminants migrate is to submit such sludges to a slow freezing in order to purify the frozen region and to concentrate impurities in the non-frozen zone. In this paper, we apply this method to model contaminated sludges consisting of clayey suspensions charged with a heavy metal (zinc). The effect of some physicochemical parameters (zinc and clay concentrations, pH) on the effectiveness of the method is experimentally investigated. The pH is the most relevant parameter and the highest purification rate (approximately 80%) is obtained for pH approximately 9.

Measuring the quality of breast cancer care: National variation in the use of radiation among women under age 70

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The National Quality Forum (NQF) recently adopted accountability cancer quality measures. Careful specification of target populations makes it so that omission of recommended therapy should be uncommon. One measure is use of radiation (RT) with breast conserving therapy (BCT) for women under age 70. This study examines nationwide use of RT in 2003–04 to determine the extent of variation and the need for improvement within these tight specifications. Methods: Data from 1,303 hospitals reporting to the National Cancer Data Base (NCDB) on women under age 70 treated with BCT in 2003–04 for invasive breast cancer were examined for factors associated with the use of RT in a multivariate model. The attributable provider unit was the reporting hospital. Results: Overall among 90,611 women under age 70, RT was reported with BCT in 74.5%. RT began within 6 months diagnosis in 54% and 1 yr in 74.2%. On multivariable analysis ( Table 1 ), RT was significantly less likely among African American and Hispanic vs. Caucasian women, those with less vs. more education, with no insurance or Medicaid vs. managed care, those with Charlson comorbidity > 0, women treated outside the Great Lakes/Midwest census regions, and treated at hospitals in the lower vs. higher quartiles of case volume. RT was administered to 73% of women in non-urban hospitals, and to 82% of women in urban hospitals. RT was administered to 75% and 77% of women age 50 - 59 and 60 - 69, respectively, compared to 68% and 72% of women age < 40 and 40 - 49. Conclusions: Despite limiting measurement to populations that should clearly receive RT with BCT, there are significant variations associated with patient and institutional characteristics. Reporting cancer care quality data is important, and the use of RT with BCT is a key quality measure for improvement and provider accountability.

[Table: see text]

No significant financial relationships to disclose.

Surface-wave interferometry on single subwavelength slit-groove structures fabricated on gold films

We apply the technique of far-field interferometry to measure the properties of surface waves generated by two-dimensional (2D) single subwavelength slit-groove structures on gold films. The effective surface index of refraction n(surf) measured for the surface wave propagating over a distance of more than 12 mum is determined to be n(surf) = 1.016+/-0.004, to within experimental uncertainty close to the expected bound surface plasmon-polariton (SPP) value for a Au/Air interface of n (spp) = 1.018. We compare these measurements to finite-difference-time-domain (FDTD) numerical simulations of the optical field transmission through these devices. We find excellent agreement between the measurements and the simulations for n(surf). The measurements also show that the surface wave propagation parameter k(surf) exhibits transient behavior close to the slit, evolving smoothly from greater values asymptotically toward k (spp) over the first 2-3 mum of slit-groove distance x(sg). This behavior is confirmed by the FDTD simulations.

Surface quality and surface waves on subwavelength-structured silver films

We analyze the physical-chemical surface properties of single-slit, single-groove subwavelength-structured silver films with high-resolution transmission electron microscopy and calculate exact solutions to Maxwell's equations corresponding to recent far-field interferometry experiments using these structures. Contrary to a recent suggestion the surface analysis shows that the silver films are free of detectable contaminants. The finite-difference time-domain calculations, in excellent agreement with experiment, show a rapid fringe amplitude decrease in the near zone (slit-groove distance out to 3-4 wavelengths). Extrapolation to slit-groove distances beyond the near zone shows that the surface wave evolves to the expected bound surface plasmon polariton (SPP). Fourier analysis of these results indicates the presence of a distribution of transient, evanescent modes around the SPP that dephase and dissipate as the surface wave evolves from the near to the far zone.

Surface wave generation and propagation on metallic subwavelength structures measured by far-field interferometry

Transmission spectra of metallic films or membranes perforated by arrays of subwavelength slits or holes have been widely interpreted as resonance absorption by surface plasmon polaritons. Alternative interpretations involving evanescent waves diffracted on the surface have also been proposed. These two approaches lead to divergent predictions for some surface wave properties. Using far-field interferometry, we have carried out a series of measurements on elementary one-dimensional subwavelength structures with the aim of testing key properties of the surface waves and comparing them to predictions of these two points of view.

Outcome of capsule endoscopy in determining indication and route for push-and-pull enteroscopy

BACKGROUND AND STUDY AIM

Video capsule endoscopy and push-and-pull enteroscopy (PPE), both allow a complete examination of the small bowel in patients with suspected intestinal disorders. Due to the invasiveness of PPE, indications should probably be selective. The aim of the present prospective study was to evaluate the outcome of an approach whereby capsule endoscopy was used to select patients in whom PPE was indicated.

PATIENTS AND METHODS

164 patients were included (90 men; age 54+/-18 years) with various indications for small-bowel investigation, such as obscure bleeding (n=88), suspected Crohn's (n=14) or celiac (n=12) disease, or known or strongly suspected localized diseases such as neoplasms (n = 18) for biopsy. Four patients with a suspected intestinal stenosis underwent PPE without prior capsule endoscopy. In the remaining 160 patients, who had a capsule endoscopy, PPE was selected if there were lesions requiring biopsy or angiodysplasias to be treated by argon plasma coagulation (APC). Regarding the insertion route, an anal PPE was indicated if the capsule transit time from ingestion to arrival at the lesion was >or= 75 % of the total time from ingestion to arrival at the cecum. After gut cleansing, PPE was performed with general anesthesia, and the small bowel was examined until the lesion was reached or the scope could not be advanced further. If the suspected lesion had not been reached, a second procedure was performed through the alternative route, under the same conditions.

RESULTS

The diagnostic yield of capsule endoscopy was 75 %. According to the indications, 47 PPE procedures were performed in 42 patients, including 33 through the oral route, 4 through the anal route and 5 combined ones. Indications were: suspicion of intestinal tumor (n=13), celiac disease with chronic bleeding (n=4), suspicion of Crohn's disease (n=3), treatment of significant arteriovenous malformations (AVMs) (n=10), diffuse enteropathies (n=3), nonsteroidal anti-inflammatory drug (NSAID)-related conditions (n=2), and obscure digestive bleeding (n=3). Lesions detected by capsule endoscopy were reached by PPE in all but two cases. The positive predictive value (PPV) of capsule endoscopy to make a correct indication for PPE was 94.7 % and the negative predictive value (NPV) was 98.3 %. The PPV and NPV of a time index of > 0.75 to start via the anal route were 94.7 % and 96.7 %. No complications were observed and all patients were discharged the day after the procedure. Follow-up at 9 months showed that capsule endoscopy followed by PPE had positively influenced the management of 90.5 % of the patients.

CONCLUSIONS

The use of capsule endoscopy as a filter for PPE results in effective management of patients with various intestinal diseases. Capsule endoscopy can also direct the choice of route of PPE; a time index of > 0.75 appears to reliably indicate an anal route so that a double procedure is required in only about 12 % of cases.

The auxin-inducible GH3 homologue Pp-GH3.16 is downregulated in Pinus pinaster root systems on ectomycorrhizal symbiosis establishment

In an attempt to determine whether auxin-regulated plant genes play a role in ectomycorrhizal symbiosis establishment, we screened a Pinus pinaster root cDNA library for auxin-upregulated genes. This allowed the identification of a cDNA, Pp-GH3.16, which encodes a polypeptide sharing extensive homologies with GH3 proteins of different plants. Pp-GH3.16 was specifically upregulated by auxins and was not affected by cytokinin, gibberellin, abscisic acid or ethylene, or by heat shock, water stress or anoxia. Pp-GH3.16 mRNAs were quantified in pine roots inoculated with two ectomycorrhizal fungi, Hebeloma cylindrosporum and Rhizopogon roseolus. Surprisingly, Pp-GH3.16 was downregulated following inoculation with both fungal species. The downregulation was most rapid on establishment of symbiosis with an indole-3-acetic acid (IAA)-overproducing mutant of H. cylindrosporum, which overproduced mycorrhizas characterized by a hypertrophic Hartig net. This indicates that, despite being auxin-inducible, Pp-GH3.16 can be downregulated on establishment of symbiosis with a fungus that releases auxin. By contrast, Pp-GH3.16 was not downregulated in pine root systems inoculated with a nonmycorrhizal mutant of H. cylindrosporum, suggesting that the downregulation we observed in mycorrhizal root systems was a component of the molecular cross-talk between symbiotic partners at the origin of differentiation of symbiotic structures.