bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influences of biological risk at birth and temperament on development at toddler and preschool ages
Authors: Hwang A‐W. , Soong W‐T. , Liao H‐F. 
Published: August 2009

AbstractPurposes  This study aimed at investigating: (1) the effects of temperament and biological risk at birth on various developmental domains at toddler and preschool ages; (2) the interaction effects of the biological risk and temperament on development.Participants  One hundred and ten full‐term and 98 preterm children without significant physical or developmental disabilities and consisting of various biological risks were examined at toddler age (18–36 months) and preschool age (51–67 months).Methods  The Neonatal Medical Index was used to classify the biological risk level. Parental reports on the Chinese Toddler Temperament Scale at toddler age were collected and the temperament (easy, intermediate and difficult) of each child was assigned according to local norm. The Comprehensive Developmental Inventory for Infants and Toddlers was used for assessing child development at toddle and preschool ages. Other family variables were also collected as possible confounders for child development. Two‐way ancova was conducted to analyse the predictability of biological risk and temperament, by controlling the potential family variables on child development.Results  At toddler age, higher biological risk had significant adverse effects on both the Perceptual‐motor developmental quotients (DQs) (F1,201= 19.4, P < 0.001) and Social‐adaptive DQs (F2,200= 22.5, P < 0.001), while easy temperament had positive effects only on the Social‐adaptive DQs (F2,200= 7.7, P < 0.01). At preschool age, none of the two factors had effects on DQs of the Comprehensive Developmental Inventory for Infants and Toddlers. There were no significant interactions between biological risk and temperament on DQs at both ages.Conclusion  The biological risk and temperament affected child development at toddler age but not at preschool age. No interaction of biological risk and temperament effects on the child development at toddler age existed. The effects of biological risk and temperament on child development were temporary for the children with relatively low biological risk.
Input of organochlorine compounds by snow to European high mountain lakes
Authors: GRIMALT JOAN O. , FERNÁNDEZ PILAR , QUIROZ ROBERTO 
Published: August 2009

Summary1. Persistent organic pollutants (POPs) can be trapped by and accumulate in cold regions. To understand POP accumulation in temperate high mountain lakes, we collected samples of snow from the catchments of several high mountain lakes in Europe.2. Organochlorine compounds (OCs) are regularly found in snow collected in European high mountain sites. Polychlorobiphenyls (PCBs) were found in all samples examined. Hexachlorocyclohexanes (HCHs) are also common whereas DDTs and hexachlorobenzene were found less frequently.3. Comparison of the concentrations of these pollutants in snow with OC levels in the waters of these lakes or atmospheric deposition during cold periods shows that the snowpack constitutes a significant seasonal PCB reservoir in all catchments and that snow trapping is a major mechanism for the incorporation of HCHs in the lakes situated in the coldest sites, e.g. Gossenköllesee in the Alps.4. Correlation of the concentrations of the PCB congeners in snow versus mean annual winter temperature shows higher accumulation at lower temperatures. The less volatile PCBs exhibit higher temperature dependences than the more volatile congeners. This trend differs from altitudinal dependences observed in other sites such as Canada and may be related to the specific range of winter temperature in each area of study.
The effects of morphology and substrate diameter on climbing and locomotor performance in male spiders
Authors: Prenter John , Pérez‐Staples Diana , Taylor Phillip W. 
Published: August 2009

Summary 1. Spiders are the most sexually size dimorphic terrestrial animals and the evolution of this dimorphism is controversial. Patterns of sexual size dimorphism (SSD) in spiders have been related to individual performance and size. In 2002 Moya‐Laraño, Halaj & Wise proposed the ‘gravity hypothesis’ to explain patterns of sexual size dimorphism in spiders whereby species building webs high in the vegetation are predicted to show greater SSD than those that build lower down. They advocated an advantage in climbing speed in smaller males searching for females in high places. The gravity hypothesis predicts a negative relationship between male size and climbing speed. In 2007 Brandt & Andrade questioned this interpretation and proposed that the pattern of SSD in spiders is better explained by an advantage for larger males of low‐dwelling species to run faster along the ground. 2. We induced male spiders to run a standard distance up vertical poles of different diameters to examine the predicted relationship between size and climbing speed. We tested two species of extremely size‐dimorphic orb‐web spiders, Argiope keyserlingi and Nephila plumipes, that differ in the height at which females tend to build webs, and one species of jumping spider, Jacksonoides queenslandica, with low levels of size dimorphism. We also examined morphological determinants of horizontal motility by inducing males to run along a raceway. 3. Substrate diameter was consistently found to influence climbing performance. In N. plumipes, climbing speed was slowest on the widest diameter substrate. In A. keyserlingi, size‐adjusted leg length and substrate diameter interacted to determine climbing speed, while in J. queenslandica, there was an interaction between body size and substrate diameter on climbing speed. In the effect of substrate diameter, we have identified a potential bias in previous tests of the gravity hypothesis. 4. Our results do not support the prediction of the gravity hypothesis. There was no evidence of a negative relationship between body size and climbing speed in the two orb‐web species with high levels of SSD. Our results are also not consistent with a recent modification of the gravity hypothesis that suggests a curvilinear relationship between climbing speed and size. 5. Body size was positively associated with maximum running speed only in the cursorial hunter J. queenslandica. For this spider, results are more consistent with Brandt & Andrade’s explanation for variation in SSD in spiders, that larger males are selected for superior running ability in low‐dwelling species, rather than selection for smaller size for climbing to females in high‐dwelling species.
Are increased concentrations of maternal corticosterone adaptive to offspring? A test using a placentotrophic lizard
Authors: Cadby Chloé D. , Jones Susan M. , Wapstra Erik 
Published: August 2009

Summary1. Maternal hormones during embryogenesis act as a bridge between the maternal and the offspring environment and consequently may allow maternal pre‐programming of offspring phenotype to the environment, assuming that maternal environment is a reliable predictor of offspring environment.2. We use an orthogonal experimental design in which we increase plasma corticosterone concentration (vs. control) in placentotrophic gravid female spotted skinks (Niveoscincus ocellatus) and their offspring. We hypothesize that high concentrations of maternal corticosterone allow offspring phenotype to be pre‐programmed to better cope with high concentrations of corticosterone after birth and, consequently, offspring would not suffer from its deleterious effects. We use growth as a measure of performance as corticosterone typically affects growth in reptiles.3. High concentrations of maternal corticosterone had significant effects on offspring body condition at birth which could have resulted from corticosterone passing through the complex placenta and/or from the indirect effects of corticosterone on maternal body condition.4. There was no indication of maternal pre‐programming to high concentrations of corticosterone postpartum: growth rate of offspring placed in the same treatment (corticosterone vs. control) than their mother was not different to growth rate of offspring placed in a different treatment than their mother.5. Maternal pre‐programming to corticosterone may not have been selected for in this species either because maternal chronic stress is not a reliable predictor of offspring chronic stress or because maternal pre‐programming does not outweigh the costs of having reduced sensitivity to the hormone, resulting in slower, less appropriate reactions in stressful conditions. This study further demonstrates the highly versatile and context‐dependent nature of maternal effects and the trade‐offs between costs and benefits of maternal pre‐programming.
Foundations of communities of practice: enablers and barriers to participation
Authors: Guldberg K. , Mackness J. 
Published: August 2009

AbstractThis research draws upon community of practice theory to explore the factors that enabled or hindered participation in an online ‘Foundations of Communities of Practice’ workshop – a course that is designed to align with Wenger's communities of practice perspective. The research used a mixed methods approach, drawing upon log‐on and posting data, questionnaires and semi‐structured interviews to explore participant experiences. The findings show that five dimensions either enabled or constrained participation. These were emotion, technology, connectivity, understanding norms and learning tensions. As enablers these dimensions led to successful participation within an online community of practice, but as constraints, they led to peripheral participation. The findings highlight implications for tutors of such courses. These include the need to (1) assess the technical expertise of participants, particularly when a number of different technological tools are used; (2) find ways to identify and evaluate emotional responses so learners can be supported in managing these; (3) ensure that participants understand the norms of a community; and (4) develop clear induction materials and processes.
A review of high‐pressure freezing preparation techniques for correlative light and electron microscopy of the same cells and tissues
Authors: MCDONALD K.L. 
Published: August 2009

SummaryIn this paper, we review some published studies using correlative light and electron microscopy methods. We further refined our criteria to include only those studies using live cells for light microscope and where high‐pressure freezing was the method of specimen preparation for electron microscopy. High‐pressure freezing is especially important for some difficult‐to‐fix samples, and for optimal preservation of ultrastructure in samples larger than a few micrometres. How the light microscope observations are done is completely sample dependent, but the choice of high‐pressure freezer depends on the speed required to capture (freeze) the biological event of interest. For events requiring high time resolution (in the 4–5 s range) the Leica EM PACT2 with rapid transfer system works well. For correlative work on structures of interest that are either non‐motile or moving slowly (minutes rather than seconds), any make of high‐pressure freezer will work. We also report on some efforts to improve the capabilities of the Leica EM PACT2 rapid transfer system.
Molecular cryo‐electron tomography of vitreous tissue sections: current challenges
Authors: NORLÉN L. , ÖKTEM O. , SKOGLUND U. 
Published: August 2009

SummaryElectron tomography of vitreous tissue sections (tissue TOVIS) allows the study of the three‐dimensional structure of molecular complexes in a near‐native cellular context. Its usage is, however, limited by an unfortunate combination of noisy and incomplete data, by a technically demanding sample preparation procedure, and by a disposition for specimen degradation during data collection. Here we outline some major challenges as experienced from the application of TOVIS to human skin. We further consider a number of practical measures as well as theoretical approaches for its future development.
Correlative fluorescence and electron microscopy in tissues: immunocytochemistry
Authors: ROBINSON J.M. , TAKIZAWA T. 
Published: August 2009

SummaryCorrelative microscopy is a collection of procedures that rely upon two or more imaging modalities to examine the same specimen. The imaging modalities employed should each provide unique information and the combined correlative data should be more information rich than that obtained by any of the imaging methods alone. Currently the most common form of correlative microscopy combines fluorescence and electron microscopy. While much of the correlative microscopy in the literature is derived from studies of model cell culture systems we have focused, primarily, on correlative microscopy in tissue samples. The use of tissue, particularly human tissue, may add constraints not encountered in cell culture systems. Ultrathin cryosections, typically used for immunoelectron microscopy, have served as the substrate for correlative fluorescence and electron microscopic immunolocalization in our studies. In this work, we have employed the bifunctional reporter FluoroNanogold. This labeling reagent contains both a fluorochrome and a gold‐cluster compound and can be imaged by sequential fluorescence and electron microscopy. This approach permits the examination of exactly the same sub‐cellular structures in both fluorescence and electron microscopy with a high level of spatial resolution.
Correlative microscopy: a potent tool for the study of rare or unique cellular and tissue events
Authors: MIRONOV A.A. , BEZNOUSSENKO G.V. 
Published: August 2009

SummaryBiological studies have relied on two complementary microscope technologies – light (fluorescence) microscopy and electron microscopy. Light microscopy is used to study phenomena at a global scale to look for unique or rare events, and it also provides an opportunity for live imaging, whereas the forte of electron microscopy is the high resolution. Traditionally light and electron microscopy observations are carried out in different populations of cells/tissues and a ‘correlative’ inference is drawn. The advent of true correlative light‐electron microscopy has allowed high‐resolution imaging by electron microscopy of the same structure observed by light microscopy, and in advanced cases by video microscopy. Thus a rare event captured by low‐resolution imaging of a population or transient events captured by live imaging can now also be studied at high resolution by electron microscopy. Here, the potential and difficulties of this approach, along with the most impressive breakthroughs obtained by these methods, are discussed.
Correlative fluorescence and transmission electron microscopy: an elegant tool to study the actin cytoskeleton of whole‐mount (breast) cancer cells
Authors: JAHN K.A. , BARTON D.A. , SU Y. , RICHES J. , KABLE E.P.W. , SOON L.L. , BRAET F. 
Published: August 2009

SummaryElucidating the structure and dynamics of lamellipodia and filopodia in response to different stimuli is a topic of continuing interest in cancer cells as these structures may be attractive targets for therapeutic purposes. Interestingly, a close functional relationship between these actin‐rich protrusions and specialized membrane domains has been recently demonstrated. The aim of this study was therefore to investigate the fine organization of these actin‐rich structures and examine how they structurally may relate to detergent‐resistant membrane (DRM) domains in the MTLn3 EGF/serum starvation model. For this reason, we designed a straightforward and alternative method to study cytoskeleton arrays and their associated structures by means of correlative fluorescence (/laser)‐ and electron microscopy (CFEM). CFEM on whole mounted breast cancer cells revealed that a lamellipodium is composed of an intricate filamentous actin web organized in various patterns after different treatments. Both actin dots and DRM's were resolved, and were closely interconnected with the surrounding cytoskeleton. Long actin filaments were repeatedly observed extending beyond the leading edge and their density and length varied after different treatments. Furthermore, CFEM also allowed us to demonstrate the close structural association of DRMs with the cytoskeleton in general and the filamentous/dot‐like structural complexes in particular, suggesting that they are all functionally linked and consequently may regulate the cell's fingertip dynamics. Finally, electron tomographic modelling on the same CFEM samples confirmed that these extensions are clearly embedded within the cytoskeletal matrix of the lamellipodium.
Towards correlative imaging of plant cortical microtubule arrays: combining ultrastructure with real‐time microtubule dynamics
Authors: BARTON D.A. , GARDINER J.C. , OVERALL R.L. 
Published: August 2009

SummaryThere are a variety of microscope technologies available to image plant cortical microtubule arrays. These can be applied specifically to investigate direct questions relating to array function, ultrastructure or dynamics. Immunocytochemistry combined with confocal laser scanning microscopy provides low resolution “snapshots” of cortical microtubule arrays at the time of fixation whereas live cell imaging of fluorescent fusion proteins highlights the dynamic characteristics of the arrays. High‐resolution scanning electron microscopy provides surface detail about the individual microtubules that form cortical microtubule arrays and can also resolve cellulose microfibrils that form the innermost layer of the cell wall. Transmission electron microscopy of the arrays in cross section can be used to examine links between microtubules and the plasma membrane and, combined with electron tomography, has the potential to provide a complete picture of how individual microtubules are spatially organized within the cortical cytoplasm. Combining these high‐resolution imaging techniques with the expression of fluorescent cytoskeletal fusion proteins in live cells using correlative microscopy procedures will usher in an radical change in our understanding of the molecular dynamics that underpin the organization and function of the cytoskeleton.
Rapid combined light and electron microscopy on large frozen biological samples
Authors: VOGELS I.M.C. , HOEBEN K.A. , VAN NOORDEN C.J.F. 
Published: August 2009

SummaryThe use of large unfixed frozen tissue samples (10 × 10 × 5 mm3) for combined light microscopy (LM) and electron microscopy (EM) is described. First, cryostat sections are applied for various LM histochemical approaches including in situ hybridization, immunohistochemistry and metabolic mapping (enzyme histochemistry). When EM inspection is needed, the tissue blocks that were used for cryostat sectioning and are stored at −80 °C, are then fixed at 4 °C with glutaraldehyde/paraformaldehyde and prepared for EM according to standard procedures. Ultrastructurally, most morphological aspects of normal and pathological tissue are retained whereas cryostat sectioning at −25 °C does not have serious damaging effects on the ultrastructure. This approach allows simple and rapid combined LM and EM of relatively large tissue specimens with acceptable ultrastructure. Its use is demonstrated with the elucidation of transdifferentiated mouse stromal elements in human pancreatic adenocarcinoma explants grown subcutaneously in nude mice. Combined LM and EM analysis revealed that these elements resemble cartilage showing enchondral mineralization and aberrant muscle fibres with characteristics of skeletal muscle cells.
Parallel habitat‐driven differences in the phylogeographical structure of two independent lineages of Mediterranean saline water beetles
Authors: ABELLÁN P. , MILLÁN A. , RIBERA I. 
Published: August 2009

AbstractIt has been hypothesized that species living in small lentic water bodies, because of the short‐term geological persistence of their habitat, should show higher dispersal ability, with increased gene flow among populations and a less pronounced phylogeographical structure. Conversely, lotic species, living in more geologically stable habitats, should show reduced dispersal and an increased phylogeographical structure at the same geographical scales. In this work we tested the influence of habitat type in two groups of aquatic Coleoptera (Nebrioporus ceresyiandOchthebius notabilisgroups, families Dytiscidae and Hydraenidae respectively), each of them with closely related species typical of lotic and lentic saline Western Mediterranean water bodies. We used mitochondrialcox1sequence data of 453 specimens of 77 populations through the range of nine species to compare a lotic vs. a lentic lineage in each of the two groups. Despite the differences in biology (predators vs. detritivorous) and evolutionary history, in both lotic lineages there was a higher proportion of nucleotide diversity among than within groups of populations, and a faster rate of accumulation of haplotype diversity (as measured by rarefaction curves) than in the lentic lineages. Similarly, lotic lineages had a higher absolute phylogenetic diversity, more remarkable considering their smaller absolute geographical ranges. By comparing closely related species, we were able to show the effect of contrasting habitat preferences in two different groups, in agreement with predictions derived from habitat stability.
Hfq negatively regulates type III secretion in EHEC and several other pathogens
Authors: Shakhnovich Elizabeth A. , Davis Brigid M. , Waldor Matthew K. 
Published: August 2009

SummaryHfq is a conserved RNA‐binding protein that regulates diverse cellular processes through post‐transcriptional control of gene expression, often by functioning as a chaperone for regulatory sRNAs. Here, we explored the role of Hfq in enterohaemorrhagic Escherichia coli (EHEC), a group of non‐invasive intestinal pathogens. EHEC virulence is dependent on a Type III secretion system encoded in the LEE pathogenicity island. The abundance of transcripts for all 41 LEE genes and more than half of confirmed non‐LEE‐encoded T3 effectors were elevated in an EHEC hfq deletion mutant. Thus, Hfq promotes co‐ordinated expression of the LEE‐encoded T3S apparatus and both LEE‐ and non‐LEE‐encoded effectors. Increased transcript levels led to the formation of functional secretion complexes capable of secreting high quantities of effectors into the supernatant. The increase in LEE‐derived transcripts and proteins was dependent on Ler, the LEE‐encoded transcriptional activator, and the ler transcript appears to be a direct target of Hfq‐mediated negative regulation. Finally, we found that Hfq contributes to the negative regulation of T3SSs in several other pathogens, suggesting that Hfq, potentially along with species‐specific sRNAs, underlies a common means to prevent unfettered expression of T3SSs.