Showing papers by "Martin Luther University of Halle-Wittenberg published in 2005"

Spatial regulation of beta-actin translation by Src-dependent phosphorylation of ZBP1.

Abstract: Localization of beta-actin messenger RNA to sites of active actin polymerization modulates cell migration during embryogenesis, differentiation and possibly carcinogenesis. This localization requires the oncofetal protein ZBP1 (Zipcode binding protein 1), which binds to a conserved 54-nucleotide element in the 3'-untranslated region of the beta-actin mRNA known as the 'zipcode'. ZBP1 promotes translocation of the beta-actin transcript to actin-rich protrusions in primary fibroblasts and neurons. It is not known how the ZBP1-RNA complex achieves asymmetric protein sorting by localizing beta-actin mRNA. Here we show that chicken ZBP1 modulates the translation of beta-actin mRNA. ZBP1 associates with the beta-actin transcript in the nucleus and prevents premature translation in the cytoplasm by blocking translation initiation. Translation only occurs when the ZBP1-RNA complex reaches its destination at the periphery of the cell. At the endpoint of mRNA transport, the protein kinase Src promotes translation by phosphorylating a key tyrosine residue in ZBP1 that is required for binding to RNA. These sequential events provide both temporal and spatial control over beta-actin mRNA translation, which is important for cell migration and neurite outgrowth.

Contrasting the Theory of Planned Behavior With the Value‐Belief‐Norm Model in Explaining Conservation Behavior1

Abstract: In this paper, we contrast the value-belief-norm (VBN) model and the theory of planned behavior (TPB) for the first time regarding their ability to explain conservation behavior. The participants represent a convenience sample of 468 university students. Using survey data and adopting previously established compound measures, structural equation analyses revealed a remarkable explanatory power for both theories: TPB's intention accounted for 95% of people's conservation behavior and VBN's personal norms accounted for 64%. Compared to the VBN model, the TPB covered its concepts more fully in terms of proportions of explained variance. More importantly, the fit statistics revealed that only the TPB depicts the relations among its concepts appropriately, whereas the VBN model does not.

Identification of a specific inhibitor of the histone methyltransferase SU(VAR)3-9

Abstract: Histone methylation plays a key role in establishing and maintaining stable gene expression patterns during cellular differentiation and embryonic development. Here, we report the characterization of the fungal metabolite chaetocin as the first inhibitor of a lysine-specific histone methyltransferase. Chaetocin is specific for the methyltransferase SU(VAR)3-9 both in vitro and in vivo and may therefore be used to study heterochromatin-mediated gene repression.

Poorly crystalline mineral phases protect organic matter in acid subsoil horizons

Abstract: Summary Soil minerals are known to influence the biological stability of soil organic matter (SOM). Our study aimed to relate properties of the mineral matrix to its ability to protect organic C against decomposition in acid soils. We used the amount of hydroxyl ions released after exposure to NaF solution to establish a reactivity gradient spanning 12 subsoil horizons collected from 10 different locations. The subsoil horizons represent six soil orders and diverse geological parent materials. Phyllosilicates were characterized by X-ray diffraction and pedogenic oxides by selective dissolution procedures. The organic carbon (C) remaining after chemical removal of an oxidizable fraction of SOM with NaOCl solution was taken to represent a stable organic carbon pool. Stable organic carbon was confirmed as older than bulk organic carbon by a smaller radiocarbon (14C) content after oxidation in all 12 soils. The amount of stable organic C did not depend on clay content or the content of dithionite–citrate-extractable Fe. The combination of oxalate-extractable Fe and Al explained the greatest amount of variation in stable organic C (R2 = 0.78). Our results suggest that in acid soils, organic matter is preferentially protected by interaction with poorly crystalline minerals represented by the oxalate-soluble Fe and Al fraction. This evidence suggests that ligand exchange between mineral surface hydroxyl groups and negatively charged organic functional groups is a quantitatively important mechanism in the stabilization of SOM in acid soils. The results imply a finite stabilization capacity of soil minerals for organic matter, limited by the area density of reactive surface sites.

Insights into Genome Plasticity and Pathogenicity of the Plant Pathogenic Bacterium Xanthomonas campestris pv. vesicatoria Revealed by the Complete Genome Sequence

Abstract: The gram-negative plant-pathogenic bacterium Xanthomonas campestris pv vesicatoria is the causative agent of bacterial spot disease in pepper and tomato plants, which leads to economically important yield losses This pathosystem has become a well-established model for studying bacterial infection strategies Here, we present the whole-genome sequence of the pepper-pathogenic Xanthomonas campestris pv vesicatoria strain 85-10, which comprises a 517-Mb circular chromosome and four plasmids The genome has a high G+C content (6475%) and signatures of extensive genome plasticity Whole-genome comparisons revealed a gene order similar to both Xanthomonas axonopodis pv citri and Xanthomonas campestris pv campestris and a structure completely different from Xanthomonas oryzae pv oryzae A total of 548 coding sequences (122%) are unique to X campestris pv vesicatoria In addition to a type III secretion system, which is essential for pathogenicity, the genome of strain 85-10 encodes all other types of protein secretion systems described so far in gram-negative bacteria Remarkably, one of the putative type IV secretion systems encoded on the largest plasmid is similar to the Icm/Dot systems of the human pathogens Legionella pneumophila and Coxiella burnetii Comparisons with other completely sequenced plant pathogens predicted six novel type III effector proteins and several other virulence factors, including adhesins, cell wall-degrading enzymes, and extracellular polysaccharides

Long-term memory: a natural mechanism for the clustering of extreme events and anomalous residual times in climate records.

Abstract: We study the statistics of the return intervals between extreme events above a certain threshold in long-term persistent records. We find that the long-term memory leads (i) to a stretched exponential distribution of the return intervals, (ii) to a pronounced clustering of extreme events, and (iii) to an anomalous behavior of the mean residual time to the next event that depends on the history and increases with the elapsed time in a counterintuitive way. We present an analytical scaling approach and demonstrate that all these features can be seen in long climate records. The phenomena should also occur in heartbeat records, Internet traffic, and stock market volatility and have to be taken into account for an efficient risk evaluation.

The prognostic value of primary tumor size in papillary and follicular thyroid carcinoma.

Abstract: BACKGROUND A delay in the diagnosis of differentiated thyroid carcinoma often leads to larger tumors, higher prevalence rates of distant metastasis, and earlier cause-specific deaths. Threshold tumor diameters for extrathyroidal growth, lymph node spread, and distant metastasis in papillary (PTC) and follicular thyroid carcinoma (FTC) remain to be defined. METHODS A comparative correlation of primary tumor size and extrathyroidal growth, lymph node spread, and distant metastasis was performed for 500 institutional patients who received surgery for PTC or FTC. RESULTS There were 366 patients with PTC (73.2%) and 134 patients with FTC (26.8%). Multifocality (23.5% vs. 9.0%; P 20 mm. Pulmonary metastasis was an earlier event than bone metastasis. CONCLUSIONS The data suggested that earlier intervention is warranted to keep suspicious thyroid nodules from growing > 20 mm (or greater than T1) and spreading to distant organs. Cancer 2005. © 2005 American Cancer Society.

Diagnosis of small bowel Crohn’s disease: a prospective comparison of capsule endoscopy with magnetic resonance imaging and fluoroscopic enteroclysis

Abstract: Background and aims: The diagnostic yield of capsule endoscopy (CE) compared with magnetic resonance imaging (MRI) in small bowel Crohn’s disease is not well established. We prospectively investigated CE, MRI, and double contrast fluoroscopy in patients with suspected small bowel Crohn’s disease. Methods: Fifty two consecutive patients (39 females, 13 males) were investigated by MRI, fluoroscopy and—if bowel obstruction could be excluded—by CE. In 25, Crohn’s disease was newly suspected while the diagnosis of Crohn’s disease (non-small bowel) had been previously established in 27. Results: Small bowel Crohn’s disease was diagnosed in 41 of 52 patients (79%). CE was not accomplished in 14 patients due to bowel strictures. Of the remaining 27 patients, CE, MRI, and fluoroscopy detected small bowel Crohn’s disease in 25 (93%), 21 (78%), and 7 (of 21; 33%) cases, respectively. CE was the only diagnostic tool in four patients. CE was slightly more sensitive than MRI (12 v 10 of 13 in suspected Crohn’s disease and 13 v 11 of 14 in established Crohn’s disease). MRI detected inflammatory conglomerates and enteric fistulae in three and two cases, respectively. Conclusion: CE and MRI are complementary methods for diagnosing small bowel Crohn’s disease. CE is capable of detecting limited mucosal lesions that may be missed by MRI, but awareness of bowel obstruction is mandatory. In contrast, MRI is helpful in identifying transmural Crohn’s disease and extraluminal lesions, and may exclude strictures.

Ordered Arrays of Silicon Nanowires Produced by Nanosphere Lithography and Molecular Beam Epitaxy

Abstract: Because of their importance in fundamental research and possible applications in nanotechnology and nanoelectronics, semiconductor nanowires have attracted much interest. In addition to the growth itself, the control of the size and location is an essential problem. Here we show the growth of ordered arrays of vertically aligned silicon nanowires by molecular beam epitaxy using prepatterned arrays of gold droplets on Si(111) substrates. The ordered arrays of gold particles were produced by nanosphere lithography.

The circadian rhythm of core temperature: origin and some implications for exercise performance.

Abstract: This review first examines reliable and convenient ways of measuring core temperature for studying the circadian rhythm, concluding that measurements of rectal and gut temperature fulfil these requirements, but that insulated axilla temperature does not. The origin of the circadian rhythm of core temperature is mainly due to circadian changes in the rate of loss of heat through the extremities, mediated by vasodilatation of the cutaneous vasculature. Difficulties arise when the rhythm of core temperature is used as a marker of the body clock, since it is also affected by the sleep-wake cycle. This masking effect can be overcome directly by constant routines and indirectly by "purification" methods, several of which are described. Evidence supports the value of purification methods to act as a substitute when constant routines cannot be performed. Since many of the mechanisms that rise to the circadian rhythm of core temperature are the same as those that occur during thermoregulation in exercise, there is an interaction between the two. This interaction is manifest in the initial response to spontaneous activity and to mild exercise, body temperature rising more quickly and thermoregulatory reflexes being recruited less quickly around the trough and rising phase of the resting temperature rhythm, in comparison with the peak and falling phase. There are also implications for athletes, who need to exercise maximally and with minimal risk of muscle injury or heat exhaustion in a variety of ambient temperatures and at different times of the day. Understanding the circadian rhythm of core temperature may reduce potential hazards due to the time of day when exercise is performed.

Prospects of Remission in Medullary Thyroid Carcinoma According to Basal Calcitonin Level

Abstract: Prediction of remission in medullary thyroid carcinoma (MTC) depends on histopathological information often unavailable before surgery. Simply requiring a venous blood sample, preoperative basal calcitonin levels may be a better indicator of remission. In this institutional series of 224 consecutive patients with MTC and elevated preoperative basal calcitonin levels, postoperative calcitonin levels normalized in 28 (62%) of 45 patients with node-negative MTC and in 18 (10%) of 177 patients with node-positive MTC. On multivariate analysis, preoperative basal calcitonin levels greater than 500 pg/ml best predicted the failure to achieve biochemical remission, followed by nodal metastasis and reoperative status. Cumulative rates of biochemical remission fell continuously with rising serum basal calcitonin in node-negative patients. Node-positive patients did not achieve biochemical remission when their preoperative basal calcitonin levels exceeded 3000 pg/ml. Nodal metastasis started emerging at basal calcitonin levels of 10-40 pg/ml (normal range, <10 pg/ml). Distant metastasis and extrathyroidal growth began appearing in patients with node-positive MTC at basal calcitonin levels of 150-400 pg/ml. There were no differences between patients with sporadic and hereditary MTC after adjusting for multiple testing. Preoperative basal calcitonin levels may thus help individualize the extent of surgery and postoperative follow-up intervals for MTC.

Autonomic dysfunction predicts mortality in patients with multiple organ dysfunction syndrome of different age groups.

Abstract: Objective:Multiple organ dysfunction syndrome (MODS) is the sequential failure of several organ systems after a trigger event, like sepsis or cardiogenic shock. Mortality rate is high, up to 70%. Autonomic dysfunction may substantially contribute to the development of MODS. Our study aimed to charac

Single Crystal Manganese Oxide Multipods by Oriented Attachment

Abstract: Nonhydrolytic sol-gel processes in organic solvents have become very popular for the synthesis of metal oxide NCs. We report an affordable, high-yield, shape-control synthesis of MnO multipod nanocrystals with a quick reaction time. The reaction yields exclusively multipods; two to six pod nanocrystals are synthesized. The mechanism leading to this hierarchical nanostructure is studied in relation with an oriented attachment mechanism; all nanocrystals are found to be single crystals. The study is completed by high-resolution TEM, X-ray powder diffraction, and magnetic measurements.

The tumor suppressor RASSF1A in human carcinogenesis: an update.

Abstract: Summary. Loss of heterozygosity of the small arm of chromosome 3 is one of the most common alterations in human cancer. Most notably, a segment in 3p21.3 is frequently lost in lung cancer and several other carcinomas. We and others have identified a novel Ras effector at this segment, which was termed Ras Association Domain family 1 (RASSF1A) gene. RASSF1 consists of two main variants (RASSF1A and RASSF1C), which are transcribed from distinct CpG island promoters. Aberrant methylation of the RASSF1A promoter region is one of the most frequent epigenetic inactivation events detected in human cancer and leads to silencing of RASSF1A. Hypermethylation of RASSF1A was commonly observed in primary tumors including lung, breast, pancreas, kidney, liver, cervix, nasopharyngeal, prostate, thyroid and other cancers. Moreover, RASSF1A methylation was frequently detected in body fluids including blood, urine, nipple aspirates, sputum and bronchial alveolar lavages. Inactivation of RASSF1A was associated with an advanced tumor stage (e.g. bladder, brain, prostate, gastric tumors) and poor prognosis (e.g. lung, sarcoma and breast cancer). Detection of aberrant RASSF1A methylation may serve as a diagnostic and prognostic marker. The functional analyses of RASSF1A reveal an involvement in apoptotic signaling, microtubule stabilization and mitotic progression. The tumor suppressor RASSF1A may act as a negative Ras effector inhibiting cell growth and inducing cell death. Thus, RASSF1A may represent an epigenetically inactivated bona fide tumor suppressor in human carcinogenesis.

The Metal Permease ZupT from Escherichia coli Is a Transporter with a Broad Substrate Spectrum

Abstract: The Escherichia coli zupT (formerly ygiE) gene encodes a cytoplasmic membrane protein (ZupT) related to members of the eukaryotic ZIP family of divalent metal ion transporters. Previously, ZupT was shown to be responsible for uptake of zinc. In this study, we show that ZupT is a divalent metal cation transporter of broad substrate specificity. An E. coli strain with a disruption in all known iron uptake systems could grow in the presence of chelators only if zupT was expressed. Heterologous expression of Arabidopsis thaliana ZIP1 could also alleviate iron deficiency in this E. coli strain, as could expression of indigenous mntH or feoABC. Transport studies with intact cells showed that ZupT facilitates uptake of 55 Fe 2 similarly to uptake of MntH or Feo. Other divalent cations were also taken up by ZupT, as shown using 57 Co 2 . Expression of zupT rendered E. coli cells hypersensitive to Co 2 and sensitive to Mn 2 . ZupT did not appear to be metal regulated: expression of a (zupT-lacZ) operon fusion indicated that zupT is expressed constitutively at a low level.

FieF (YiiP) from Escherichia coli mediates decreased cellular accumulation of iron and relieves iron stress

Abstract: The Escherichia coli yiiP gene encodes an iron transporter, ferrous iron efflux (FieF), which belongs to the cation diffusion facilitator family (CDF). Transcription of fieF correlated with iron concentration; however, expression appeared to be independent of the ferrous iron uptake regulator Fur. Absence of FieF led to decreased growth of E. coli cells in complex growth medium but only if fur was additionally deleted. The presence of EDTA was partially able to relieve this growth deficiency. Expression of fieF in trans rendered the double deletion strain more tolerant to iron. Furthermore, E. coli cells exhibited reduced accumulation of (55)Fe when FieF was expressed in trans. FieF catalyzed active efflux of Zn(II) in antiport with protons energized by NADH via the transmembrane pH gradient in everted membrane vesicles. Using the iron-sensitive fluorescent indicator PhenGreen-SK encapsulated in proteoliposomes, transmembrane fluxes of iron cations were measured with purified and reconstituted FieF by fluorescence quenching. This suggests that FieF is an iron and zinc efflux system, which would be the first example of iron detoxification by efflux in any organism.

Occludin as direct target for glucocorticoid‐induced improvement of blood–brain barrier properties in a murine in vitro system

Abstract: Homeostasis of the central nervous system (CNS) microenvironment is essential for its normal function. It is maintained by the blood–brain barrier (BBB) which regulates the transport of molecules from blood into brain and backwards. The integrity of the BBB is compromised in many disorders of the human CNS; therapeutical strategies for several of these diseases include treatment with glucocorticoids, but the molecular basis of how glucocorticoids regulate BBB permeability is not understood. Here, we report the generation and characterization of a murine immortalized brain (cerebral) capillary endothelial (cEND) cell line which expresses the BBB marker occludin at intercellular tight junctions (TJ). Hydrocortisone at physiological concentrations induced upregulation of occludin, accompanied by a threefold enhancement of transendothelial electrical resistance to values up to 1000 Ωcm2. Insulin enhanced the glucocorticoid response. At the molecular level, hydrocortisone induces increase of occludin at protein and mRNA levels by activation of the glucocorticoid receptor (GR) and its binding to putative glucocorticoid responsive elements in the occludin promoter. At the same time, insulin potentiated the ligand-dependent GR transactivation via induction of the GR in this in vitro system. This study thus provides insights into the molecular processes of barrier genesis, and may help to elucidate mechanisms of brain pathology at the microvascular level.

Global invasions of the western honeybee (Apis mellifera) and the consequences for biodiversity

Abstract: The western honeybee, Apis mellifera, has been globally transported for honey production and pollination for hundreds of years and is often kept in large numbers in beekeeping operations. Concern has been expressed that it might act as an invasive species with large impact on biodiversity. However, although the honeybee has spread into the wild and has established feral populations in Australia and the Americas, the extent to which introduced honeybees alter biodiversity remains controversial. Here we focus on the best documented cases of A. mellifera invasions and discuss the effects on biodiversity under three different conditions: 1) regions where other subspecies of A. mellifera are endemic (Europe, Africa, and western Asia), 2) regions where A. mellifera is not endemic, but other species of Apis naturally occur (central and eastern Asia), 3) regions where Apis species are not endemic (America, Australia). Although some studies show an impact on native bee survival, fecundity, or population d...