bluuebunny/crossref_metadata_2025 huggingface dataset:
Aboveground Biomass Removal by Burning and Raking Increases Diversity in a Reconstructed Prairie
Authors: Tix D. , Charvat I.
Published: March 2005

Prescribed spring burning often contributes to a predominance of C4grasses and low forb abundance and is impractical at many sites, especially near development. We tested raking after mowing as an alternative to prescribed burning in a reconstructed Minnesota prairie. We also tested mowing without raking as a possible means of maintaining prairie communities. Frequency, flowering stem abundance, and cover were measured for all plant species and native functional groups (C4grasses, C3graminoids, forbs, legumes, and annual or biennial forbs). Mowing alone did not differ from the control in its effect on any functional groups of plants. Round‐headed bush clover (Lespedeza capitata), a legume, and Black‐eyed Susan (Rudbeckia hirta), a biennial, increased in frequency with treatments that removed biomass (i.e., fire or raking), but they did not have significantly more flowering stems. Thus, new plants established well from seed, whereas the vitality of mature plants did not change. Raking had similar effects to burning on most functional groups, although flowering stems of C4grasses were significantly more abundant after fire than after raking. Burning reduced some C3forbs and grasses and favored the dominance of C4grasses. Therefore, raking after mowing in the spring provides an alternative to prescribed burning that has many of the same positive aspects as fire but does not promote aggressive C4grasses to the same extent.
Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China
Authors: Shu W. S. , Ye Z. H. , Zhang Z. Q. , Lan C. Y. , Wong M. H.
Published: March 2005

Mine tailings can have a specific assemblage of plant species due to their unique physicochemical properties, and this process can be important in developing ecological theory and restoration practice. Physicochemical properties and natural colonization of plants on five lead/zinc (Pb/Zn) mine tailings in southern China were investigated. The tailings studied included Fankou and Lechang in Guangdong Province, and Huangshaping, Shuikoushan, and Taolin in Hunan Province. Physicochemical properties of the tailings varied greatly both among and within tailings ponds, but in general, all contained high concentrations of heavy metals (Pb, Zn, Cu, and Cd) and low concentrations of N, P, and organic matter. Toxic levels of heavy metals and deficiency of major nutrients appeared to be the major constraints for colonization of plants on these Pb/Zn tailings and were reflected in the metal concentration of the plant tissues. The natural colonization of plants on these tailings was limited, with only some small patches distributed mainly on the edge of tailing ponds and even fewer patches on the center of the ponds. In total 54 plant species belonging to 51 genera and 24 families were recorded on the five tailings ponds, of which the 13 species belonging to Gramineae were major components of the tailings’ flora. Species establishing on the tailings at the initial colonization phase greatly depended on their seed‐dispersal capacity. Further establishment and growth were then dependent on at least one of the three ecological strategies: (1) microsite (avoidance) strategy: plant establishment on tailings depended on dispersing onto microsites of relatively favorable edaphic conditions; (2) tolerance strategy: plant establishment was a result of evolving metal‐tolerant ecotypes or constitutional metal tolerance; and (3) rhizome strategy: plant establishment on tailings depended on clonal growth by rhizomatous extension.
Soil Biological and Chemical Properties in Restored Perennial Grassland in California
Authors: Potthoff M. , Jackson L. E. , Steenwerth K. L. , Ramirez I. , Stromberg M. R. , Rolston D. E.
Published: March 2005

Restoration of California native perennial grassland is often initiated with cultivation to reduce the density and cover of non‐native annual grasses before seeding with native perennials. Tillage is known to adversely impact agriculturally cultivated land; thus changes in soil biological functions, as indicated by carbon (C) turnover and C retention, may also be negatively affected by these restoration techniques. We investigated a restored perennial grassland in the fourth year after planting Nassella pulchra, Elymus glaucus, and Hordeum brachyantherum ssp. californicum for total soil C and nitrogen (N), microbial biomass C, microbial respiration, CO2 concentrations in the soil atmosphere, surface efflux of CO2, and root distribution (0‐ to 15‐, 15‐ to 30‐, 30‐ to 60‐, and 60‐ to 80‐cm depths). A comparison was made between untreated annual grassland and plots without plant cover still maintained by tillage and herbicide. In the uppermost layer (0‐ to 15‐cm depth), total C, microbial biomass C, and respiration were lower in the tilled, bare soil than in the grassland soils, as was CO2 efflux from the soil surface. Root length near perennial bunchgrasses was lower at the surface and greater at lower depths than in the annual grass–dominated areas; a similar but less pronounced trend was observed for root biomass. Few differences in soil biological or chemical properties occurred below 15‐cm depth, except that at lower depths, the CO2 concentration in the soil atmosphere was lower in the plots without vegetation, possibly from reduced production of CO2 due to the lack of root respiration. Similar microbiological properties in soil layers below 15‐cm depth suggest that deeper microbiota rely on more recalcitrant C sources and are less affected by plant removal than in the surface layer, even after 6 years. Without primary production, restoration procedures with extended periods of tillage and herbicide applications led to net losses of C during the plant‐free periods. However, at 4 years after planting native grasses, soil microbial biomass and activity were nearly the same as the former conditions represented by annual grassland, suggesting high resilience to the temporary disturbance caused by tillage.
Polytrichum Strictumas a Solution to Frost Heaving in Disturbed Ecosystems: A Case Study with Milled Peatlands
Authors: Groeneveld E.V. G. , Rochefort L
Published: March 2005

Substrate instability is a common problem in many disturbed ecosystems. In the case of milled harvested peatlands, the pioneer mossPolytrichum strictumis commonly found; it is well adapted to tolerate the harsh microclimatic conditions and peat instability of these sites. A field experiment was used to determine the effectiveness ofP. strictumagainst frost heaving, a major type of disturbance on bare peat. Wooden dowels and fir trees (Abies balsamea) placed in aP. strictumcarpet experienced almost no frost heaving, whereas heaving was severe on bare peat. ReintroducedP. strictumfragments thinly spread on bare peat reduced but did not eliminate frost heaving. Straw mulch (a protective cover often required in peatland restoration) effectively reduced heaving in the fall, but was less effective in the spring because it had partially decomposed. TheP. strictumcarpet,P. strictumfragments, and straw mulch reduced frost heaving by reducing the number of freeze–thaw cycles, by slowing the rate of ground thaw in the spring, and by reducing the unfrozen water content of the peat during the spring thaw. Different species ofPolytrichummosses should be considered for the restoration or regeneration of disturbed ecosystems where soil stability is problematic.
The Two‐Culture Problem: Ecological Restoration and the Integration of Knowledge
Authors: Higgs E
Published: March 2005

The terms “ecological restoration” and “restoration ecology” are frequently interchanged. Restoration ecology is the suite of scientific practices that constitute an emergent subdiscipline of ecology. Ecological restoration is the ensemble of practices that constitute the entire field of restoration, including restoration ecology as well as the participating human and natural sciences, politics, technologies, economic factors, and cultural dimensions. This paper is motivated by the concern that the broader practice of restoration may become narrowed over the next decade as a result of zealous attention to scientific and technological considerations, and that restoration ecology will trump ecological restoration. Scientific and technological acumen is necessary for successful restoration, but insufficient. Maintaining a broader approach to restoration requires respect for other kinds of knowledge than science, and especially the recognition of a moral center that is beyond the scope of science to address fully. An example of integrated restoration is presented: the ecological and cultural restoration of Discovery Island (near Victoria, British Columbia, Canada) by the Lekwungen people (Songhees First Nation).
On the Cusp of Restoration: Science and Society
Authors: Turner R.E.
Published: March 2005

Habitat restoration has reached political respectability at many scales across the Earth and represents a serious reversal of some entrenched social views regarding the environment as a strictly exploitable resource for private gain. Science helps improve restoration by bringing clarity in the form of order, understanding, and descriptions of uncertainty. But scientific ideas and experience must be offered in a timely manner and welcomed to be a useful and accurate part of restoration. These ideas may be adopted or fail to be influential for vastly different reasons. Valid ideas may be untimely or be packaged too poorly to be acceptable, or an idea may be erroneous, but still be acceptable (and lead to poor decisions) where the ability to convince or superior networking skills compensate for an inadequacy of facts, logic, or intentions. The most desirable outcome is to fairly weigh all relevant ideas during decision‐making, and without confusing accuracy and clarity with consensus or deliberative inclusivity. Project scale influences these outcomes because social and policy complexity increases with project size. Ideas, of whatever origin, must be applied in the imperfectly comprehended landscape and “policy‐scape” of policies and personal preferences influencing the spatial productivity, richness, and uses. Successful habitat restoration will have the science welcomed and developing in well‐ventilated and professional ways, while simultaneously participating in the world of the larger policy‐scape. Judgments will be made and mistakes occur, of course. But, if done well, we may end up restoring habitats, institutions and parts of society.
Balancing the Need to Develop Coastal Areas with the Desire for an Ecologically Functioning Coastal Environment: Is Net Ecosystem Improvement Possible?
Authors: Thom R.M. , Williams G.W. , Diefenderfer H.L.
Published: March 2005

The global human population is growing exponentially, close to a majority lives and works near the coast, and coastal commerce and development are critical to the economies of many nations. Hence, coastal areas will continue to be a major focus of development and economic activity. People desire the economic advantages provided by coastal development along with the fisheries and social commodities supported by estuarine and coastal ecosystems. Because of these facts, we view the challenge of balancing coastal development with enhancing nearshore marine and estuarine ecosystems (i.e., net ecosystem improvement) as the top priority for coastal researchers in this century. Our restoration research in Pacific Northwest estuaries and participation in nearshore project design and impact mitigation has largely dealt with these competing goals. To this end, we have applied conceptual models, comprehensive assessment methods, and principles of restoration ecology, conservation biology, and adaptive management to incorporate science into decisions about uses of estuarine systems. Case studies of Bainbridge Island and the Columbia River demonstrate the use of objective, defensible methods to prioritize tidally influenced shorelines and habitats (i.e., riparian forests, marshes, unvegetated flats, rocky shores, seagrass meadows, kelp forests) for preservation, conservation, and restoration. Case studies of Clinton, Washington, and Port Townsend, Washington, demonstrate the incorporation of an ecological perspective and technological solutions into design of overwater structures to minimize impacts on nearshore ecosystems. Adaptive management has allowed coastal development and restoration uncertainties to be better evaluated, with the information used to improve management decisions. Although unproven on a large scale, we think these kinds of methods can contribute to the net improvement of already degraded ecosystems. The ingredients include applied science to understand the issues, education, incentives, empirical data, cumulative impact analysis, and an effective adaptive management program. Because the option of net ecosystem improvement is often more costly than alternatives such as no net loss, commitment by the local or regional community to this approach is essential.
Ecological Rehabilitation of the Schelde Estuary (The Netherlands–Belgium; Northwest Europe): Linking Ecology, Safety Against Floods, and Accessibility for Port Development
Authors: Van den Bergh E , Van Damme S , Graveland J , De Jong D , Baten I , Meire P
Published: March 2005

The Long‐Term Vision for the Schelde estuary was determined as “the development of a healthy and multifunctional estuarine water system that can be utilized in a sustainable way for human needs.” This Dutch–Flemish managerial plan sets quality targets for the condition of the estuary by the year 2030 and the management measures to achieve them. Targets were developed and integrated from three central perspectives: accessibility of the ports, safety against floods in the densely populated catchment, and ecosystem health. This study focuses on the ecological rehabilitation of the estuary and the creation of sustainable nature, seeking possible alliances with security measures against floods, navigation requisites for port activities, and enhancement of the estuary's educational and recreational values. The estuary and its valley were subdivided into ecologically relevant zones. Key parameters were identified, and a conceptual rehabilitation model was developed, based on a problem analysis. Goals were set in a semiquantified way for most attributes of the estuarine functioning and prioritized for each zone. Rehabilitation measures with maximal contribution to the priority goals were identified for each zone. Spatial analysis of the study area indicated optimal areas for the implementation of these measures. To exemplify the array of possibilities on an ecosystem level, two different rehabilitation plans were proposed, each from a different approach. The potential contribution to the rehabilitation of the estuary was compared for both alternatives.
Beach Nourishment and Coastal Habitats: Research Needs to Improve Compatibility
Authors: Nordstrom K.F.
Published: March 2005

Beach nourishment creates many opportunities for resource development and use, but it also creates new issues regarding cumulative, long‐term losses in borrow areas and appropriate human actions in fill areas. Nourished beaches should be considered as more than consumptive resources built for shore protection and recreation. Assessments of nourishment projects in the United States are used to identify research needed to address impacts on species and habitats in borrow areas and restoration of natural subenvironments in nourished areas. Achieving these goals involves changes in stakeholder attitudes about the meaning of beach nourishment and development of research initiatives to demonstrate the scientific, technologic, and economic feasibility of methods that are more compatible with maintaining or restoring natural landforms and habitats. Suggestions are made for expanding the spatial and temporal scales of investigation, evaluating alternative beach and sediment types, identifying new uses for fill, evaluating alternative technologies and practices, implementing adaptive management strategies, assessing stakeholder attitudes and capabilities, overcoming cost constraints, and conducting interdisciplinary studies.
Ploidy analysis of field cancerization and cancer development in the hamster cheek pouch carcinogenesis model
Authors: Raimondi A. , Cabrini R. , Itoiz M. E.
Published: March 2005

Background:  The hamster cheek‐pouch carcinogenesis model is a well‐known animal system that closely mimics the development of premalignant and malignant lesions in human oral cancer. Our aim was to numerically characterize the premalignant and malignant lesions and expressions of field cancerization in this model using ploidy as the end‐point.

Methods:  To study the DNA content and proliferation status of the cells in this model we assessed the Feulgen reaction and the immunohistochemical reaction for 5‐bromo‐2‐deoxiuridine (BrdU) in different histological areas of serial tissue sections of the cheek pouches of animals injected with BrdU.

Results:  Ploidy values were higher in cancerized epithelia with no unusual microscopic features (NUMF), in preneoplastic and tumor areas than in control epithelia. The aneuploidy index was higher in NUMF areas than in control and differed significantly from control in preneoplastic areas and carcinoma.

Conclusions:  The unexpected alteration in DNA content observed in NUMF epithelia is of great relevance as a biomarker of field cancerized areas.
Successful treatment of an extensive verrucous carcinoma with topical 5‐aminolevulinic acid‐mediated photodynamic therapy
Authors: Chen Hsin‐Ming , Chen Chin‐Tin , Yang Hsiang , Lee Ming‐I , Kuo Mark Yen‐Ping , Kuo Ying‐Shiung , Wang Yi‐Ping , Tsai Tsuimin , Chiang Chun‐Pin
Published: March 2005

Our recent study found that a new topical 5‐aminolevulinic acid‐mediated photodynamic therapy (ALA‐PDT) protocol composed of multiple 3‐min fractionated irradiations with a light emitting diode (LED) red light at 635 ± 5 nm for a total of 1000 s (fluence rate: 100 mW/cm2; light exposure dose: 100 J/cm2) after topical application of 20% ALA for 1.5 or 2 h can be used successfully for the treatment of oral verrucous hyperplasia. In this case report, we tested the efficacy of this new treatment protocol of ALA‐PDT for an extraoral verrucous carcinoma (VC) lesion at the right mouth angle and an intraoral VC lesion at the right buccal mucosa of a 56‐year‐old male areca quid chewer and smoker. The extraoral tumor was cleared after six treatments of topical ALA‐PDT and the intraoral tumor showed complete regression after 22 treatments of topical ALA‐PDT. No recurrence of the VC lesion was found after a follow‐up period of 6 months. We suggest that PDT using a topical application of 20% ALA followed by multiple 3‐min fractionated irradiations with an LED red light is also an effective and successful treatment modality for VC.
Expression of p63 protein and mRNA in oral epithelial dysplasia
Authors: Chen Yuk‐Kwan , Hsue Shui‐Sang , Lin Li‐Min
Published: March 2005

Background:  Abnormalities in the TP53 are regarded as the most consistent findings in oral squamous cell carcinoma. Two related members of the TP53 family, p73 and p63, have shown remarkable structural similarity to TP53, indicating possible functional and biological interactions. The aim of the present study was to investigate the expression of p63 protein and mRNA in oral epithelial dysplasia.

Methods:  Immunohistochemical p63 staining was compared for samples from 90 male patients with buccal epithelial dysplasias and 15 healthy individuals with normal buccal mucosa and 15 subjects with reactive epithelial hyperplasia of the oral mucosa secondary to traumatic insult. The buccal lesions consisted of mild, moderate and severe epithelial dysplasias (30 samples in each category). The mRNA expression using reverse transcription polymerase chain reaction (RT–PCR) was also included for a subset of available fresh tissue specimens (four samples in each category of mild and moderate epithelial dysplasia; five samples in severe epithelial dysplasia; five samples in each of normal and reactive epithelial hyperplasia).

Results:  Nuclear p63 staining was demonstrated predominantly in the basal layers of the epithelium of the normal buccal mucosa and reactive epithelial hyperplasia specimens. For epithelial dysplasia lesions, however, staining was not restricted to the basal layers, extending to the middle spinous layer for samples in the mild category, with p63 immunoexpression observed across almost the full thickness of the dysplastic epithelium for analogous moderate and severe specimens. Compared with normal/reactive hyperplastic mucosa, p63 staining in the dysplastic mucosa was significantly increased. The severity of dysplasia was increased with the increase of p63 staining. Furthermore, ΔNp63mRNA was identified in all of the fresh tissue samples whereas expression of transactivation (TA) isotype was not detected. A subset of moderate epithelial dysplasia and severe variant showing p63‐positive staining has undergone malignant transformation to squamous cell carcinomas in about 5 years follow‐up.

Conclusion:  Our results indicate that impaired p63 immunoexpression (predominantly ΔN isoform) is associated with the severity of oral epithelial dysplasias and up‐regulation of p63 may play a role in the early stage of human oral tumorigenesis.
Assessment of SS‐A and SS‐B in parotid saliva of patients with Sjögren's syndrome
Authors: Hammi Ann Rose , Al‐Hashimi Ibtisam H. , Nunn Martha E. , Zipp Michele
Published: March 2005

Background:  The purpose of this study was to compare the sensitivity of parotid saliva to that of serum in detecting anti‐SSA/Ro and anti‐SSB/La autoantibodies in patients with Sjögren's syndrome.

Methods:  Forty patients and 20 controls participated in the study; all patients met the 1993 European Community criteria for the diagnosis of Sjögren's syndrome. Healthy controls were age‐ and sex‐matched individuals with no signs or symptoms of Sjögren's syndrome. Serum and saliva samples were evaluated using AffiniTech SSA/Ro and SSB/La antibodies kits (AffiniTech, Ltd. Bentonville, AR, USA). The results were also compared with serological status of SS‐A and SS‐B as reported by an independent clinical laboratory.

Results:  Serum was significantly more sensitive than saliva in detecting SSA/Ro and SSB/La antibodies (P = 0.001). There was high agreement between the results with the AffiniTech kits and the independent laboratory (kappa = 0.80; P < 0.001). However, there was poor agreement between saliva and serum results (kappa = 0.174; P = 0.168).

Conclusions:  The overall results appear to support that serum analysis is effective method for evaluating the presence of SS‐A and SS‐B autoantibodies.
Morphological changes of regional lymph node in squamous cell carcinoma of the oral cavity
Authors: Okura Masaya , Kagamiuchi Hajime , Tominaga Gyo , Iida Seiji , Fukuda Yasuo , Kogo Mikihiko
Published: March 2005

Background:  Regional immune responses with various types of cancer have been studied histopathologically, however, the prognostic value remains conflicting. The aim of this study was to evaluate morphological changes related to lymph node metastasis and the prognostic value for oral cavity squamous cell carcinoma.

Methods:  With histopathologic whole architecture of 430 lymph nodes, gross area, germinal center (GC) area, paracortical area (PA), and tumor area were measured.

Results:  Metastatic node had significantly lower distribution ratio of PA to lymphoarea than that of tumor‐free node. GC area was not constantly associated with lymph node metastasis. In Cox multivariate analysis, the mean ratio of PA to gross area/lymphoarea was an independent prognostic factor.

Conclusions:  The proportion of PA to gross/lymph area was associated with lymph node metastasis and long‐term survival and may be useful in stratification of those patients for a requirement of adjuvant treatments.
Randomized‐controlled trial: effect of a reservoir biteguard on quality of life in xerostomia
Authors: Robinson Peter G. , Pankhurst Caroline L. , Garrett Emma J.
Published: March 2005

Background:  To assess the effect of a reservoir biteguard for artificial saliva on the oral health‐related quality of life of patients with xerostomia.

Methods:  Double‐blind randomized placebo‐controlled trial among 86 adults with xerostomia. Study group received the trial biteguard. Control group received a conventional biteguard. Outcomes were number of impacts and total scores as recorded by oral impacts on daily performances (OIDP).

Results:  At 1‐month follow up 84 people remained in the trial. The median number of impacts in the study and control groups was 3 and 4 respectively. The median total score was 6 and 12 respectively. In ANCOVA receipt of the reservoir biteguard reduced the number of impacts recorded by OIDP but there was no difference in the total score.

Conclusions:  Reservoir biteguards improved the quality of life of people with xerostomia by reducing the number of impacts on daily life.
An ultrastructural and a cytochemical study of candidal invasion of reconstituted human oral epithelium
Authors: Jayatilake J. A. M. S. , Samaranayake Y. H. , Samaranayake L. P.
Published: March 2005

Background:  Opportunistic yeast, Candida albicans causes superficial and systemic mycoses in compromised patients. Adhesion to host tissues, morphogenesis and extracellular phospholipases (PL) are thought to contribute to its virulence. The nature of numerous host–parasite interactions at the invasive phase of oral candidiasis is not fully understood. Hence in this study, we explore the ultrastructural features of oral candidiasis using a tissue culture model based on reconstituted human oral epithelium (RHOE).

Methods:  Reconstituted human oral epithelium (Skinethic Laboratory, Nice, France) was inoculated with C. albicans SC5314 and incubated up to 48 h. The infected tissue was harvested at 12, 24 and 48 h and examined using light, scanning (SEM) and transmission electron microscopy (TEM). Localized activity of PLs of C. albicans during tissue invasion was also examined using a cytochemical method.

Results:  Over a period of 48 h C. albicans invaded the RHOE, and histological examination revealed characteristic hallmarks of pathological tissue invasion. Hyphal penetration into the superficial epithelium, particularly at cell junctions, together with features of cellular internalization of yeasts was noted. Phospholipase activity was visible at the tips of hyphae and initial sites of bud formation. Further, SEM studies revealed cavitations on the surface epithelial cells particularly pronounced at the sites of hyphal invasion. Hyphal invasion was seen both at cell surfaces and intercellular cell junctions of the epithelium, the latter resembling thigmotropic behaviour.

Conclusions:  Our findings confirm that multiple cellular interactions such as internalization, thigmotropism and extracellular PLs contribute to invasive candidiasis. The RHOE model, described here, appears to be a satisfactory model for the investigation of ultrastructural and histochemical features of invasive candidiasis in humans.
Ultraviolet protective performance of photoprotective lipsticks: change of spectral transmittance because of ultraviolet exposure
Authors: Maier H. , Schauberger G. , Martincigh B. S. , Brunnhofer K. , Hönigsmann H.
Published: March 2005

Background: Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well‐known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours.

Objectives: To assess the change of the spectral transmission after UV exposure (UV‐challenged protective performance) of 27 commercially available photoprotective lipsticks.

Methods: Quartz slides were covered with a lipstick layer (area density 1.0±0.1 mg/cm2) and irradiated with increasing doses of solar‐simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, ΔT, and the arithmetic mean, for both the UVA (ΔTA) and UVB (ΔTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, ΔTA, or UVB range, ΔTB, was higher than 5% for an UV exposure of 12.5 SED.

Results: Eleven products showed a significant photoinstability in the UVA range (ΔTA between 6% and 27%), only one product in the UVB range (ΔTB=13%), and one product in both the UVA (ΔTA=31%) and UVB (ΔTB=9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures.

Conclusions: Out of 27 lipsticks only 13 products showed a photostable performance (ΔTA<5% and ΔTB<5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.
Core Formation and the Acquisition of Fusion Competence are Linked During Secretory Granule Maturation in Tetrahymena
Authors: Bowman Grant R. , Elde Nels C. , Morgan Garry , Winey Mark , Turkewitz Aaron P.
Published: March 2005

The formation of dense core secretory granules is a multistage process beginning in the trans Golgi network and continuing during a period of granule maturation. Direct interactions between proteins in the membrane and those in the forming dense core may be important for sorting during this process, as well as for organizing membrane proteins in mature granules. We have isolated two mutants in dense core granule formation in the ciliate Tetrahymena thermophila, an organism in which this pathway is genetically accessible. The mutants lie in two distinct genes but have similar phenotypes, marked by accumulation of a set of granule cargo markers in intracellular vesicles resembling immature secretory granules. Sorting to these vesicles appears specific, since they do not contain detectable levels of an extraneous secretory marker. The mutants were initially identified on the basis of aberrant proprotein processing, but also showed defects in the docking of the immature granules. These defects, in core assembly and docking, were similarly conditional with respect to growth conditions, and therefore are likely to be tightly linked. In starved cells, the processing defect was less severe, and the immature granules could dock but still did not undergo stimulated exocytosis. We identified a lumenal protein that localizes to the docking‐competent end of wildtype granules, but which is delocalized in the mutants. Our results suggest that dense cores have functionally distinct domains that may be important for organizing membrane proteins involved in docking and fusion.
Crossing the Divide – Transport Between the Endoplasmic Reticulum and Golgi Apparatus in Plants
Authors: Hanton Sally L. , Bortolotti Lauren E. , Renna Luciana , Stefano Giovanni , Brandizzi Federica
Published: March 2005

The transport of proteins between the endoplasmic reticulum (ER) and the Golgi apparatus in plants is an exciting and constantly expanding topic, which has attracted much attention in recent years. The study of protein transport within the secretory pathway is a relatively new field, dating back to the 1970s for mammalian cells and considerably later for plants. This may explain why COPI‐ and COPII‐mediated transport between the ER and the Golgi in plants is only now becoming clear, while the existence of these pathways in other organisms is relatively well documented. We summarize current knowledge of these protein transport routes, as well as highlighting key differences between those of plant systems and those of mammals and yeast. These differences have necessitated the study of plant‐specific aspects of protein transport in the early secretory pathway, and this review discusses recent developments in this area. Advances in live‐cell‐imaging technology have allowed the observation of protein movement in vivo, giving a new insight into many of the processes involved in vesicle formation and protein trafficking. The use of these new technologies has been combined with more traditional methods, such as protein biochemistry and electron microscopy, to increase our understanding of the transport routes in the cell.
Exiting the Endoplasmic Reticulum
Authors: Mancias Joseph D. , Goldberg Jonathan
Published: March 2005

Vesicular transport from the endoplasmic reticulum (ER) to the Golgi complex constitutes the initial step in protein secretion. COPII‐coated vesicles mediate the export of newly synthesized proteins from the ER, and this transport step is coupled with COPI‐mediated retrograde traffic to form a transport circuit that supports the compositional asymmetry of the ER–Golgi system. Biochemical and structural studies have advanced our understanding of the mechanisms that control vesicle formation and cargo–protein capture. Recent work has highlighted the function of transitional ER regions in specifying the location of COPII budding.
Oxidative stress in the hippocampus after pilocarpine‐induced status epilepticus in Wistar rats
Authors: Freitas Rivelilson M. , Vasconcelos Silvânia M. M. , Souza Francisca C. F. , Viana Glauce S. B. , Fonteles Marta M. F.
Published: March 2005

The role of oxidative stress in pilocarpine‐induced status epilepticus was investigated by measuring lipid peroxidation level, nitrite content, GSH concentration, and superoxide dismutase and catalase activities in the hippocampus of Wistar rats. The control group was subcutaneously injected with 0.9% saline. The experimental group received pilocarpine (400 mg·kg−1, subcutaneous). Both groups were killed 24 h after treatment. After the induction of status epilepticus, there were significant increases (77% and 51%, respectively) in lipid peroxidation and nitrite concentration, but a 55% decrease in GSH content. Catalase activity was augmented 88%, but superoxide dismutase activity remained unaltered. These results show evidence of neuronal damage in the hippocampus due to a decrease in GSH concentration and an increase in lipid peroxidation and nitrite content. GSH and catalase activity are involved in mechanisms responsible for eliminating oxygen free radicals during the establishment of status epilepticus in the hippocampus. In contrast, no correlations between superoxide dismutase and catalase activities were observed. Our results suggest that GSH and catalase activity play an antioxidant role in the hippocampus during status epilepticus.
Increased NADPH concentration obtained by metabolic engineering of the pentose phosphate pathway in Aspergillus niger
Authors: R. Poulsen Bjarne , Nøhr Jane , Douthwaite Stephen , Hansen Line V. , Iversen Jens J. L. , Visser Jaap , Ruijter George J. G.
Published: March 2005

Many biosynthetic reactions and bioconversions are limited by low availability of NADPH. With the purpose of increasing the NADPH concentration and/or the flux through the pentose phosphate pathway in Aspergillus niger, the genes encoding glucose 6‐phosphate dehydrogenase (gsdA), 6‐phosphogluconate dehydrogenase (gndA) and transketolase (tktA) were cloned and overexpressed in separate strains. Intracellular NADPH concentration was increased two‐ to ninefold as a result of 13‐fold overproduction of 6‐phosphogluconate dehydrogenase. Although overproduction of glucose 6‐phosphate dehydrogenase and transketolase changed the concentration of several metabolites it did not result in increased NADPH concentration. To establish the effects of overexpression of the three genes, wild‐type and overexpressing strains were characterized in detail in exponential and stationary phase of bioreactor cultures containing minimal media, with glucose as the carbon source and ammonium or nitrate as the nitrogen source and final cell density limiting substrate. Enzymes, intermediary metabolites, polyol pools (intra‐ and extracellular), organic acids, growth rates and rate constant of induction of acid production in postexponential phase were measured. None of the modified strains had a changed growth rate. Partial least square regressions showed the correlations between NADPH and up to 40 other variables (concentration of enzymes and metabolites) and it was possible to predict the intracellular NADPH concentration from relatively easily obtainable data (the concentration of enzymes, polyols and oxalate). This prediction might be used in screening for high NADPH levels in engineered strains or mutants of other organisms.
Flavonol 3‐O‐glycoside hydroxycinnamoyltransferases from Scots pine (Pinus sylvestris L.)
Authors: Kaffarnik Florian , Heller Werner , Hertkorn Norbert , Sandermann Heinrich
Published: March 2005

Flavonol 3‐O‐glucosides esterified with ferulic or p‐coumaric acid at positions 3′′ and 6′′ are the major UV‐B screening pigments of the epidermal layer of Scots pine (Pinus sylvestris) needles. The last steps in the biosynthesis of these compounds are catalyzed by enzymes that transfer the acyl part of hydroxycinnamic acid CoA esters to flavonol 3‐O‐glucosides. A newly developed enzyme assay revealed three flavonol 3‐O‐glucoside hydroxycinnamoyltransferases (HCTs) in Scots pine needles with specificities for positions 3′′, 4′′ or 6′′. The positions of the acyl groups were identified by cochromatography with reference compounds and by NMR spectroscopy. The enzymes were characterized by molecular mass, isoelectric point, and also pH and temperature optima. Substrate specificities for flavonol glycosides and hydroxycinnamic acid CoA esters as well as kinetic properties of 3′′‐ and 6′′HCT suggested that acylation preferably occurs with glucosides and p‐coumaroyl‐CoA. In addition, acylation takes place in a well‐defined order, beginning at position 6′′ followed by acylation at position 3′′. These results give the first detailed characterization of flavonol 3‐O‐glycoside HCTs involved in the protection of plant tissues against UV‐B (280–315 nm) radiation.
Influence of divalent cations on the structural thermostability and thermal inactivation kinetics of class II xylose isomerases
Authors: Epting Kevin L. , Vieille Claire , Zeikus J. Gregory , Kelly Robert M.
Published: March 2005

The effects of divalent metal cations on structural thermostability and the inactivation kinetics of homologous class II d‐xylose isomerases (XI; EC 5.3.1.5) from mesophilic (Escherichia coli and Bacillus licheniformis), thermophilic (Thermoanaerobacterium thermosulfurigenes), and hyperthermophilic (Thermotoga neapolitana) bacteria were examined. Unlike the three less thermophilic XIs that were substantially structurally stabilized in the presence of Co2+ or Mn2+ (and Mg2+ to a lesser extent), the melting temperature [(Tm) ≈100 °C] of T. neapolitana XI (TNXI) varied little in the presence or absence of a single type of metal. In the presence of any two of these metals, TNXI exhibited a second melting transition between 110 °C and 114 °C. TNXI kinetic inactivation, which was non‐first order, could be modeled as a two‐step sequential process. TNXI inactivation in the presence of 5 mm metal at 99–100 °C was slowest in the presence of Mn2+[half‐life (t1/2) of 84 min], compared to Co2+ (t1/2 of 14 min) and Mg2+ (t1/2 of 2 min). While adding Co2+ to Mg2+ increased TNXI's t1/2 at 99–100 °C from 2 to 7.5 min, TNXI showed no significant activity at temperatures above the first melting transition. The results reported here suggest that, unlike the other class II XIs examined, single metals are required for TNXI activity, but are not essential for its structural thermostability. The structural form corresponding to the second melting transition of TNXI in the presence of two metals is not known, but likely results from cooperative interactions between dissimilar metals in the two metal binding sites.
Identification of alternative promoter usage for the matrix Gla protein gene
Authors: Conceição Natércia , Silva Ana C. , Fidalgo João , Belo José A. , Cancela M. Leonor
Published: March 2005

Recent cloning of the Xenopus laevis (Xl) matrix Gla protein (MGP) gene indicated the presence of a conserved overall structure for this gene between mammals and amphibians but identified an additional 5′‐exon, not detected in mammals, flanked by a functional, calcium‐sensitive promoter, 3042 bp distant from the ATG initiation codon. DNA sequence analysis identified a second TATA‐like DNA motif located at the 3′ end of intron 1 and adjacent to the ATG‐containing second exon. This putative proximal promoter was found to direct transcription of the luciferase reporter gene in the X. laevis A6 cell line, a result confirmed by subsequent deletion mutant analysis. RT‐PCR analysis of XlMGP gene expression during early development identified a different temporal expression of the two transcripts, strongly suggesting differential promoter activation under the control of either maternally inherited or developmentally induced regulatory factors. Our results provide further evidence of the usefulness of nonmammalian model systems to elucidate the complex regulation of MGP gene transcription and raise the possibility that a similar mechanism of regulation may also exist in mammals.
Inhibitory properties of cystatin F and its localization in U937 promonocyte cells
Authors: Langerholc Tomaž , Zavašnik‐Bergant Valentina , Turk Boris , Turk Vito , Abrahamson Magnus , Kos Janko
Published: March 2005

Cystatin F is a recently discovered type II cystatin expressed almost exclusively in immune cells. It is present intracellularly in lysosome‐like vesicles, which suggests a potential role in regulating papain‐like cathepsins involved in antigen presentation. Therefore, interactions of cystatin F with several of its potential targets, cathepsins F, K, V, S, H, X and C, were studied in vitro. Cystatin F tightly inhibited cathepsins F, K and V with Ki values ranging from 0.17 nm to 0.35 nm, whereas cathepsins S and H were inhibited with 100‐fold lower affinities (Ki ≈ 30 nm). The exopeptidases, cathepsins C and X were not inhibited by cystatin F. In order to investigate the biological significance of the inhibition data, the intracellular localization of cystatin F and its potential targets, cathepsins B, H, L, S, C and K, were studied by confocal microscopy in U937 promonocyte cells. Although vesicular staining was observed for all the enzymes, only cathepsins H and X were found to be colocalized with the inhibitor. This suggests that cystatin F in U937 cells may function as a regulatory inhibitor of proteolytic activity of cathepsin H or, more likely, as a protection against cathepsins misdirected to specific cystatin F containing endosomal/lysosomal vesicles. The finding that cystatin F was not colocalized with cystatin C suggests distinct functions for these two cysteine protease inhibitors in U937 cells.
Liver X receptor agonists inhibit tissue factor expression in macrophages
Authors: Terasaka Naoki , Hiroshima Ayano , Ariga Akiko , Honzumi Shoko , Koieyama Tadashi , Inaba Toshimori , Fujiwara Toshihiko
Published: March 2005

Exposure of blood to tissue factor (TF) rapidly initiates the coagulation serine protease cascades. TF is expressed by macrophages and other types of cell within atherosclerotic lesions and plays an important role in thrombus formation after plaque rupture. Macrophage TF expression is induced by pro‐inflammatory stimuli including lipopolysaccharide (LPS), interleukin‐1β and tumor necrosis factor‐α. Here we demonstrate that activation of liver X receptors (LXRs) LXRα and LXRβ suppresses TF expression. Treatment of mouse peritoneal macrophages with synthetic LXR agonist T0901317 or GW3965 reduced TF expression induced by pro‐inflammatory stimuli. LXR agonists also suppressed TF expression and its activity in human monocytes. Human and mouse TF promoters contain binding sites for the transcription factors AP‐1, NFκB, Egr‐1 and Sp1, but no LXR‐binding sites could be found. Cotransfection assays with LXR and TF promoter constructs in RAW 264.7 cells revealed that LXR agonists suppressed LPS‐induced TF promoter activity. Analysis of TF promoter also showed that inhibition of TF promoter activity by LXR was at least in part through inhibition of the NFκB signaling pathway. In addition, in vivo, LXR agonists reduced TF expression within aortic lesions in an atherosclerosis mouse model as well as in kidney and lung in mice stimulated with LPS. These findings indicate that activation of LXR results in reduction of TF expression, which may influence atherothrombosis in patients with vascular disease.
The connection between star formation and stellar mass: specific star formation rates to redshift one
Authors: Feulner Georg , Goranova Yuliana , Drory Niv , Hopp Ulrich , Bender Ralf
Published: March 2005

We investigate the contribution of star formation to the growth of stellar mass in galaxies over the redshift range 0.5 < ɀ < 1.1 by studying the redshift evolution of the specific star formation rate (SSFR), defined as the star formation rate per unit stellar mass. We use an I-band-selected sample of 6180 field galaxies from the Munich Near-Infrared Cluster Survey (MUNICS) with spectroscopically calibrated photometric redshifts. The SSFR decreases with stellar mass at all redshifts. The low SSFRs of massive galaxies indicate that star formation does not significantly change their stellar mass over this redshift range: the majority of massive galaxies have assembled the bulk of their mass before redshift unity. Furthermore, these highest mass galaxies contain the oldest stellar populations at all redshifts. The line of maximum SSFR runs parallel to lines of constant star formation rate. With increasing redshift, the maximum SFR is generally increasing for all stellar masses, from SFR ≃ 5 M⊙ yr−1 at ɀ≃ 0.5 to SFR ≃ 10 M⊙ yr−1 at ɀ ≃ 1.1. We also show that the large SSFRs of low-mass galaxies cannot be sustained over extended periods of time. Finally, our results do not require a substantial contribution of merging to the growth of stellar mass in massive galaxies over the redshift range probed. We note that highly obscured galaxies which remain undetected in our sample do not affect these findings for the bulk of the field galaxy population.
The discovery of a type II quasar at ɀ = 1.65 with integral-field spectroscopy
Authors: Jarvis Matt J. , van Breukelen Caroline , Wilman R. J.
Published: March 2005

In this Letter we report the serendipitous discovery of a genuine type II quasar at ɀ = 1.65 using integral-field data from the Visual Multi-Object Spectrograph (VIMOS) on the Very Large Telescope (VLT). This is the first discovery of a type II quasar at ɀ > 1 from optical data alone. J094531-242831, hereafter J0945-2428, exhibits strong narrow (v < 1500 km s−1) emission lines, has a resolved host galaxy, and is undetected to a radio flux density limit of S5 GHz = 0.15 mJy (3σ). All of these characteristics lead us to believe that J0945-2428 is a bona fide type II quasar.

The luminosity of the narrow emission lines in this object suggest that the intrinsic power of the central engine is similar to that found in powerful radio galaxies, indicative of a similarly large supermassive black hole of ∼ 3 × 108 M⊙ (assuming that it is accreting at its Eddington limit). However, from near-infrared imaging observations we find that the old stellar population in the host galaxy has a luminosity of ∼ 0.2 L★, mildly inconsistent with the correlation between black hole mass and bulge luminosity found locally, although the uncertainty in the black hole mass estimate is large.

This discovery highlights the power that integral-field units have in discovering hidden populations of objects, particularly the sought-after type II quasars, which are invoked to explain the hard X-ray background. As such, future large integral-field surveys could open up a new window on the obscured accretion activity in the Universe.