bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecology‐based screen identifies new metabolites from a Cordyceps‐colonizing fungus as cancer cell proliferation inhibitors and apoptosis inducers
Authors: Chen Y. , Guo H. , Du Z. , Liu X.‐Z. , Che Y. , Ye X. 
Published: August 2009

AbstractObjectives:  This study aims to identify new anti‐cancer agents from Cordyceps‐colonizing fungi, using an ecology‐based approach. It also aims to explore their anti‐cell proliferative mechanisms, and to evaluate their anti‐tumour effects in vivo.Materials and methods:  Extracts from Cordyceps‐colonizing fungi were tested on HeLa cells, and active extracts were separated to obtain anti‐tumour metabolites; their structures were elucidated by mass and nuclear magnetic resonance spectroscopy. Cell cycle analysis was evaluated using flow cytometry. Tumour formation assays were performed using C57BL/6J mice.Results:  Based on ecological considerations, the selected extracts were subjected to initial anti‐tumour screening. Bioassay‐guided fractionation of the active extract afforded two new epipolythiodioxopiperazines, named gliocladicillins A (1) and B (2). (A) 1 and B (2) inhibited growth of HeLa, HepG2 and MCF‐7 tumour cells. Further study demonstrated that both preparations arrested the cell cycle at G2/M phase in a dose‐dependent manner, and induced apoptosis through up‐regulation of expression of p53, p21, and cyclin B, and activation of caspases‐8, ‐9 and ‐3. These data imply that gliocladicillins A (1) and B (2) induce tumour cell apoptosis through both extrinsic and intrinsic pathways. In addition, in vivo studies showed that they displayed significant inhibitory effects on cell population growth of melanoma B16 cells imlanted into immunodeficient mice.Conclusions:  Gliocladicillins A (1) and B (2) are effective anti‐tumour agents in vitro and in vivo and should be further evaluated for their potential in clinical use.
Erosion of telomeric single‐stranded overhang in patients with aplastic anaemia carrying telomerase complex mutations
Authors: Calado R. T. , Regal J. A. , Kajigaya S. , Young N. S. 
Published: August 2009

AbstractBackground  Loss‐of‐function mutations in telomerase complex genes reduce telomerase activity and shorten overall telomere length in leucocytes, and they can clinically manifest as bone marrow failure (aplastic anaemia and dyskeratosis congenita) and familial pulmonary fibrosis. Telomeres are constituted of double‐stranded tandem TTAGGG repeats followed by a 3′ G‐rich single‐stranded overhang, a crucial telomeric structural component responsible for the t‐loop formation.Materials and methods  We investigated the length of telomeric overhangs in 25 healthy individuals from 0 to 76 years of age, 16 patients with aplastic anaemia, and 13 immediate relatives using a non‐denaturing in‐gel method and the telomere‐oligonucleotide ligation assay.Results  Telomeric overhang lengths were constant from birth to eighth decade of life in healthy subjects, in contrast to overall telomere length, which shortened with ageing. Most patients with marrow failure and a telomerase gene mutation showed marked erosion of telomeric overhang associated with critically short telomeres; in other aplastic patients with normal genotypes, normal overall telomere lengths and who responded to immunosuppressive therapy, telomeric overhangs were maintained.Conclusions  Telomeric overhang erosion does not participate in physiological ageing but support a role for eroded telomeric overhangs and abnormal telomere structure in pathological shortening of telomeres, especially caused by loss‐of‐function telomerase mutations. Disrupted telomere structure caused by short telomeric overhangs may contribute to the mechanisms of abnormal haematopoietic compartment senescence and chromosomal instability in human bone marrow failure.
The influence of planktivorous fish on zooplankton communities in riverine slackwaters
Authors: NING NATHAN S. P. , NIELSEN DARYL L. , HILLMAN TERRY J. , SUTER PHILLIP J. 
Published: August 2009

Summary1. Contrary to that for lakes and ponds, our knowledge of the influence of planktivorous fish on zooplankton communities in rivers is slight, largely because of the general assumption that such communities are overwhelmingly regulated by physical conditions.2. In two separate but concurrent in situ enclosure experiments, we investigated the effects of carp gudgeon (Hypseleotris spp.) and Eastern Gambusia (Gambusia holbrooki) on zooplankton communities in slackwaters of a temperate Australian floodplain river.3. A high biomass of Hypseleotris suppressed the density of daphniid microcrustaceans, but enhanced the total density of rotifers. A high biomass of Gambusia, on the other hand, suppressed the total density of both microcrustaceans and rotifers.4. A high biomass of planktivorous fish also reduced the density of many of the ovigerous (egg‐carrying) zooplanktonic taxa. Indeed, ovigerous cyclopoid copepods were suppressed in the presence of a high biomass of Hypseleotris, even though there was no significant effect on overall (ovigerous plus non‐ovigerous) density.5. Our results imply that a high biomass of planktivorous fish can potentially influence zooplankton communities in riverine slackwaters, as in many lakes and ponds.
Integrating plant–soil interactions into global carbon cycle models
Authors: Ostle Nicholas J. , Smith Pete , Fisher Rosie , Ian Woodward F. , Fisher Joshua B. , Smith Jo U. , Galbraith David , Levy Peter , Meir Patrick , McNamara Niall P. , Bardgett Richard D. 
Published: August 2009

Summary 1. Plant–soil interactions play a central role in the biogeochemical carbon (C), nitrogen (N) and hydrological cycles. In the context of global environmental change, they are important both in modulating the impact of climate change and in regulating the feedback of greenhouse gas emissions (CO2, CH4 and N2O) to the climate system. 2. Dynamic global vegetation models (DGVMs) represent the most advanced tools available to predict the impacts of global change on terrestrial ecosystem functions and to examine their feedbacks to climate change. The accurate representation of plant–soil interactions in these models is crucial to improving predictions of the effects of climate change on a global scale. 3. In this paper, we describe the general structure of DGVMs that use plant functional types (PFTs) classifications as a means to integrate plant–soil interactions and illustrate how models have been developed to improve the simulation of: (a) soil carbon dynamics, (b) nitrogen cycling, (c) drought impacts and (d) vegetation dynamics. For each of these, we discuss some recent advances and identify knowledge gaps. 4. We identify three ongoing challenges, requiring collaboration between the global modelling community and process ecologists. First, the need for a critical evaluation of the representation of plant–soil processes in global models; second, the need to supply and integrate knowledge into global models; third, the testing of global model simulations against large‐scale multifactor experiments and data from observatory gradients. 5. Synthesis. This paper reviews how plant–soil interactions are represented in DGVMs that use PFTs and illustrates some model developments. We also identify areas of ecological understanding and experimentation needed to reduce uncertainty in future carbon coupled climate change predictions.
Estimation of variance components of local stereological volume estimators: a pilot study
Authors: PAWLAS Z. , NYENGAARD J.R. 
Published: August 2009

SummaryLocal stereological techniques can be used for particle volume estimation based on information collected on a section plane through a reference point of the particle. We present methods for variability estimation of the local stereological volume estimators. This variability arises during the stereological estimation procedure and in the particle population. Both of these components can be estimated separately from planar sections. Our aim is to give a preliminary analysis of the possibility to include the particle structure interaction into the estimation procedure. For this reason, not only the section profiles, but also their locations, have to be recorded. The methods are applied for the sectional data obtained from neurons in the hippocampal brain region subiculum of four 3‐month‐old male Wistar rats. The proposed procedure enables one to obtain information about particle volume distribution.
The impact of sleep duration and subject intelligence on declarative and motor memory performance: how much is enough?
Authors: TUCKER MATTHEW A. , FISHBEIN WILLIAM 
Published: August 2009

SummaryRecent findings clearly demonstrate that daytime naps impart substantial memory benefits compared with equivalent periods of wakefulness. Using a declarative paired associates task and a procedural motor sequence task, this study examined the effect of two lengthier durations of nocturnal sleep [either a half night (3.5 h) or a full night (7.5 h) of sleep] on over‐sleep changes in memory performance. We also assessed whether subject intelligence is associated with heightened task acquisition and, more importantly, whether greater intelligence translates to greater over‐sleep declarative and procedural memory enhancement. Across both tasks, we demonstrate that postsleep performance gains are nearly equivalent, regardless of whether subjects obtain a half night or a full night of sleep. Remarkably, the over‐sleep memory changes observed on both tasks are very similar to findings from studies examining performance following a daytime nap. Consistent with previous research, we also observed a strong positive correlation between amount of Stage 2 sleep and motor skill performance in the full‐night sleep group. This finding contrasts with a highly significant correlation between spectral power in the spindle frequency band (12–15 Hz) and motor skill enhancement only in the half‐night group, suggesting that sigma power and amount of Stage 2 sleep are both important for optimal motor memory processing. While subject intelligence correlated positively with acquisition and retest performance on both tasks, it did not correlate with over‐sleep changes in performance on either task, suggesting that intelligence may not be a powerful modulator of sleep’s effect on memory performance.
Attachment of Streptomyces coelicolor is mediated by amyloidal fimbriae that are anchored to the cell surface via cellulose
Authors: De Jong Wouter , Wösten Han A. B. , Dijkhuizen Lubbert , Claessen Dennis 
Published: August 2009

SummaryThe chaplin proteins ChpA‐H enable the filamentous bacterium Streptomyces coelicolor to form reproductive aerial structures by assembling into surface‐active amyloid‐like fibrils. We here demonstrate that chaplins also mediate attachment of S. coelicolor to surfaces. Attachment coincides with the formation of fimbriae, which are connected to the cell surface via spike‐shaped protrusions. Mass spectrometry, electron microscopy and Congo red treatment showed that these fimbriae are composed of bundled amyloid fibrils of chaplins. Attachment and fimbriae formation were abolished in a strain in which the chaplin genes chpA–H were inactivated. Instead, very thin fibrils emerged from the spike‐shaped protrusions in this mutant. These fibrils were susceptible to cellulase treatment. This enzymatic treatment also released wild‐type fimbriae from the cell surface, thereby abolishing attachment. The reduced attachment of a strain in which the gene of a predicted cellulose synthase was inactivated also indicates a role of cellulose in surface attachment. We propose that the mechanism of attachment via cellulose‐anchored amyloidal fimbriae is widespread in bacteria and may function in initiation of infection and in formation of biofilms.
The burden of COPD in Africa: a literature review and prospective survey of the availability of spirometry for COPD diagnosis in Africa
Authors: Mehrotra Anushka , Oluwole Akanbi Maxwell , Gordon Stephen B. 
Published: August 2009

SummaryObjectives  To ascertain the known burden of chronic obstructive pulmonary disease (COPD) in Africa and of spirometry use to indicate the possibility of further unpublished data becoming shortly available.Method  Literature review.Results  Screening of 132 articles yielded 22 relevant articles, of which only six used spirometry based data. A total of 106 physicians in 34 countries were contacted and only 23 reported satisfactory use and availability of spirometry.Conclusions  Current estimates of COPD burden in Africa are based on an unreliably small dataset. Acquisition of further data will require substantial investment in lung function equipment and training.
Quality of life in simultaneous pancreas–kidney transplant recipients
Authors: Pera Pilar Isla , Vasallo Joaquin Moncho , Rabasa Alberto Torras , Salinas Federico Oppenheimer , Pérez Laureano Fernández Cruz , Brulles María José Ricart 
Published: August 2009

Abstract: Background: Simultaneous pancreas‐kidney transplantation (SPK Tx) allows dialysis and insulin therapy to be discontinued and improves the complications of diabetes mellitus type 1 (DM1). This study measure quality of life (QoL) in SPK transplant recipients and determine if there are differences in QoL between these patients and those with DM1 in renal replacement therapy (RRT).Methods: Short Form Health Survey 36‐Item (SF‐36) was administered to 69 SPK transplant recipients and 34 patients with DM1 under RRT. A descriptive analysis, multiple linear regression, ANOVA, and ordinal regression (PLUM) models were constructed.Results: QoL was higher in SPK transplant recipients than in patients receiving RRT. The best results were in the recently transplanted patients. Respect to Spanish population the men with SPK transplants scored higher on vitality and lower on general health, role limitations‐physical and role limitations‐emotional. Women with SPK transplants scored lower on general health. Among patients under RRT, men scored lower on the general health, physical functioning, vitality, and bodily pain while women scored lower on all dimensions. In both groups, greater age was associated with better mental health.Conclusion: Positive predictive factors of QoL are SPK Tx and age while negative predictive factors are female sex and RRT.
HLA‐B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy
Authors: Andresdottir Margret B. , Haasnoot Geert W. , Persijn Guido G. , Claas Frans H.J. 
Published: August 2009

Abstract: Background: The HLA‐B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients.Methods: From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non‐glomerular diseases. Death‐censored graft loss according to the HLA‐B8, DR3 haplotype was calculated with Kaplan–Meier analysis and Cox‐regression model was used to correct for various risk factors.Results: The frequency of the HLA‐B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten‐year graft survival was identical in the control group with and without the HLA‐B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA‐B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA‐B8, DR3 haplotype and independent of well‐known risk factors.Conclusions: We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.
Neighbor–Stranger Discrimination in Concave‐Eared Torrent Frogs, Odorrana tormota
Authors: Feng Albert S. , Arch Victoria S. , Yu Zulin , Yu Xin‐Jian , Xu Zhi‐Min , Shen Jun‐Xian 
Published: August 2009

AbstractThe dear enemy phenomenon in which animals discriminate familiar neighbors from unknown strangers, and respond more aggressively to strangers is well established in various social animals, especially in songbirds and mammals. So far, very few studies of neighbor–stranger discrimination have been carried out in amphibians and the results have been mixed. Thus, it is unclear whether this phenomenon exists commonly in frogs and toads, and whether it is exhibited by species with large vocal repertoires. We conducted acoustic playback experiments with male concave‐eared torrent frogs (Odorrana tormota, a species with an unusually large vocal repertoire) kept in a tank in a quiet room to investigate whether or not they can discriminate strangers from neighbors acoustically. Nine of the 14 males tested showed evoked vocal responses to the calls from strangers, but none to calls from neighbors; vocal response to the calls from strangers was accompanied by aggressive motor activity. These results demonstrate that male O. tormota possess the ability to discriminate neighbors from strangers acoustically. Odorrana tormota therefore joins three ranid species (Rana catesbiana, Rana clamitans, Rana dalmatina, all known to have a comparatively small and stereotyped vocal repertoires) as the only anurans demonstrated to have this ability. Given the difference in signaling complexity between these frog species, the salient acoustic features used for discriminating neighbors and strangers are likely to be quite distinct.
Observational Learning in the White‐Eared Hummingbird (Hylocharis leucotis): Experimental Evidence
Authors: Lara Carlos , González Juan M. , Hudson Robyn 
Published: August 2009

AbstractThe adoption of new food resources can be facilitated by the ability to learn through observation of other individuals who use them. This behavior, termed observational learning, applies to any problem solving in which a naive individual who has observed an experienced individual learns a behavior faster than another who has not. Hummingbirds consume nectar from flowers of a large number of plant species, which are very diverse in morphology and color. During their local or migratory movements, they can observe the use of floral resources by conspecifics and heterospecifics which may change their foraging preferences. Although there is evidence that hummingbirds can use observational learning to exploit new floral resources, it is necessary to generate additional information by studying different hummingbird species. In this work, the learning performance of White‐eared hummingbirds (Hylocharis leucotis) was studied in the presence or absence of a knowledgeable tutor. In a first experiment, naïve hummingbirds learned to feed on arrays of artificial flower of two colors: red (previously known resource) and yellow (novel resource), where only one color had nectar. Naive hummingbirds visited red flowers faster and more often than rewarded yellow flowers. Individuals with the best performance on each color were further trained to ensure that they only visited flowers of a specific color, and were then used as tutors in the next experiment, in which new naive hummingbirds, caged individually, were allowed to observe them foraging on the artificial arrays. These naïve individual were then exposed alone to the same array used by their tutor. Tutored hummingbirds learned to feed faster and more frequently from nectar‐containing flowers of the array than naive individuals. Likewise, all tutored individuals only visited flowers of the color that had been previously visited by their tutors. This study provides experimental evidence that hummingbirds taken directly from the field can use observational learning as an efficient strategy to access new floral resources.
Response Specificity to Advertisement Vocalization in the Chinese Alligator (Alligator sinensis)
Authors: Wang Xianyan , Wang Ding , Wu Xiaobing , Wang Chaolin , Wang Renping , Xia Tongsheng 
Published: August 2009

AbstractStringency in the identification of conspecific call properties is essential among sympatric species to ensure conspecific mating, as the risk of improper recognition and heterospecific mating is high. In this study we investigated the basic signal structure required for intraspecies communication in the Chinese alligator (Alligator sinensis), a species that has no relatives living in sympatry, by playback of signals modified in the temporal (truncating original bellows with first 1/4, 1/2, 3/4 or last 1/4, 1/2, 3/4 portion) or frequency domain (with low‐ or high‐pass filters at frequencies 100, 250, 500 and 1000 Hz), or by reversal of natural bellows. The playback experiments revealed that relatively large modifications in bellow temporal or frequency structure failed to impair Chinese alligators’ bellowing behavior; even reversed bellows effectively evoked a positive response. In general, the first half of the bellow in temporal domain and frequencies below 500 Hz were critical for behavioral induction, while the last half of the bellow in temporal domain and frequencies above 500 Hz failed to produce a single positive response, implying a potential functional signal redundancy. The observed high tolerance to bellow variations in Chinese alligators may be an evolutionary adaptation to (1) the acoustic constraints of propagation imposed by dense vegetative habitats; or (2) a lack of selection pressure due to the low risk of incorrect conspecific recognition and heterospecific mating.
Song Perch Height in Rufous‐and‐White Wrens: Does Behaviour Enhance Effective Communication in a Tropical Forest?
Authors: Barker Nicole K. S. , Mennill Daniel J. 
Published: August 2009

AbstractAnimal signals are distorted as they transmit through the environment, but many species have evolved strategies to minimize distortion of vocal signals. Song structure can change over evolutionary time, or signallers can modify their behaviour, to reduce attenuation and degradation in a specific habitat. We investigated signalling behaviour in rufous‐and‐white wrens, Thyothorus rufalbus, a Neotropical songbird in which both sexes sing, with a specific focus on perch height. Based on previous findings, including a detailed sound transmission study, we predicted that rufous‐and‐white wrens would choose elevated song perches in order to maximize the distance their songs travel, and that males and females would show different perch height choices. We observed 30 birds in 18 territories in a tropical forest in Costa Rica to determine the perch heights of birds when singing, producing non‐song vocalizations, collecting nesting material, foraging, and engaging in other behaviours. We found that both activity and sex influenced perch height. Birds sang from a variety of heights, but the highest perches were used as song posts by males. Males minimized singing from within 1 m of the ground, and they generally perched higher than females, which may reflect sex differences in communication strategies. Both sexes foraged on or near the ground. The finding that rufous‐and‐white wrens vary their perch height with specific activities suggests that they modify their singing behaviour to enhance long‐distance communication.