bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of segmentation techniques for digital dermoscopy
Authors: Joel Guillod , Philippe Schmid‐Saugeon , David Guggisberg , Jean Philippe Cerottini , Ralph Braun , Joakim Krischer , Jean‐Hilaire Saurat , Murat Kunt 
Published: March 2003

Purpose: This study aims at evaluating two automatic contour detection techniques especially developed for dermoscopic images.Methods: Twenty‐five images of lesions with a fuzzy boundary have been randomly selected. Five dermatologists experienced in dermoscopy have manually drawn the border of all the lesions and repeated the procedure after two and four weeks. The ability of a dermatologist to reproduce its own results was evaluated by measuring the non‐overlapping area enclosed by its three successive contours. The interobserver variability evaluated the contour accuracy when using automatic or manual drawings. The mean probability that a pixel has been misclassified was computed for every observer and automatic technique.Results: Experts in dermoscopy are not able to reproduce measurements precisely and the two automatic techniques had a lower missclassification probability than those obtained by each dermatologist.Conclusion: This study demonstrates that a single dermatologist should not be used as a reference, and subjective validation of lesion contour is inaccurate outside an experts's group. It is argued that image processing techniques for computer‐aided diagnosis must show the best compromise within such a group.
A Progestin Antagonist Blocks Vaginocervical Stimulation‐Induced Fos Expression in Neurones Containing Progestin Receptors in the Rostral Medial Preoptic Area
Authors: Blaustein J. D. , Gréco B. 
Published: March 2003

AbstractVaginocervical stimulation (VCS) has a variety of effects on the brain, physiology and behaviour. Previous work demonstrated that a progestin antagonist blocked neuronal response to VCS (i.e. Fos expression) in the absence of progesterone in some neurones, and suggested that some of the effects of VCS on the brain are mediated by ligand‐independent activation of progestin receptors (PRs). Although it had been reported previously that some of the cells in which VCS induces Fos expression also contain PRs, it had not been determined if a progestin antagonist blocked Fos expression in these particular neurones. The purpose of this experiment was to determine if a progestin antagonist decreases Fos expression specifically in cells that also express PRs in the preoptic area and ventromedial hypothalamus. As has been shown previously, VCS increased Fos‐immunoreactive (ir) expression in the particular areas studied. In the rostral medial preoptic area, VCS increased Fos expression in cells that coexpressed PRs, as well as in cells that do not. However, in the caudal medial preoptic area, VCS only increased Fos expression in cells that did not coexpress PRs. Injection of the progestin antagonist, RU 486, decreased Fos expression in the rostral, but not caudal medial preoptic area, and it decreased Fos expression only in cells that coexpressed PR‐ir. In contrast to a previous report, in the present study, the progestin antagonist did not inhibit VCS‐induced Fos expression in the ventromedial hypothalamic area. The results of this experiment suggest that the progestin antagonist inhibits VCS‐induced Fos expression in some neurones by blocking PRs, and they provide further support for the idea that VCS influences neuronal response in some cells by ligand‐independent activation of PRs in those cells.
Cellular responses to elevated light levels in Fucus spiralis embryos during the first days after fertilization
Authors: Coelho S. , Rijstenbil J. W. , Sousa‐Pinto I. , Brown M. T. 
Published: March 2003

AbstractCellular responses of 1‐, 2‐ and 4‐d‐old Fucus spiralis embryos subjected to a single dose of elevated photosynthetically active photon flux density (PPFD), with or without ultraviolet (UV) radiation, were investigated by measuring the effects on the effective quantum yield of photosystem II (ΔF / Fm′) and intracellular production of active oxygen species (AOS). Production of AOS was determined by the in vivo conversion of 5‐(and‐6)‐chloromethyl‐2′,7′‐dichlorodihydrofluorescein diacetate (CM‐DCFH2‐DA) to the fluorescent compound dichlorofluorescein (DCF) using confocal laser scan microscopy (CLSM) and image analysis. The role of xanthophyll cycle pigments in photoprotection was also assessed. A rapid decline in ΔF / Fm′ was observed under all elevated light conditions. A correlation was found between non‐photochemical quenching and the de‐epoxidation ratio zeaxanthin/(zeaxanthin + violoxanthin). Active oxygen formation increased with PPFD and was higher in older embryos and when UVB was present. Two photoinhibition responses were recognized: (i) a rapid decline of the PSII yield due to the violoxanthin–zeaxanthin cycle (photoprotection), and (ii) a slower second‐phase decline, correlated with active oxygen production. Electron transport rate (ETR) increased with embryo age, and was correlated with AOS production. As a result of enhanced AOS production, there was a slow recovery of the PSII yield, in particular with increased effective UV dose. In general, embryos were able to recover from the imposed light conditions, but UVB had a more damaging effect. Overall, our data suggest that under natural conditions, embryos of F. spiralis are susceptible to elevated light levels, and that UVB radiation is an important stress factor.
High salt‐treatment‐induced Na+ extrusion and low salt‐treatment‐induced Na+ accumulation in suspension‐cultured cells of the mangrove plant, Bruguiera sexangula
Authors: Kura‐Hotta M. , Mimura M. , Tsujimura T. , Washitani‐Nemoto S. , Mimura T. 
Published: March 2003

AbstractA suspension‐cultured cell strain of the mangrove plant (Bruguiera sexangula) was established from a callus culture and maintained in an amino acid medium in the absence of NaCl. NaCl non‐adapted cells were transferred to media containing 0–200 mm NaCl. The initial growth rate decreased gradually with increasing salt concentrations. However, at up to 150 mm NaCl, cell number growth at the highest point was almost the same as that at lower salt concentrations. Cells even continued to grow in the presence of 200 mm NaCl.Cells incubated in a medium containing 50 mm NaCl for 3 weeks accumulated Na+, while those incubated in 150 mm NaCl for 2 d showed only a transient increase in Na+ and Cl– concentrations. In the latter treatment, the intracellular concentration of Na+ returned to the original low level within 2 weeks. It took a longer time for Cl– to return to its original level. As a result, the Na+ and Cl– concentrations in cells cultured with 50 mm NaCl were much larger than those in cells cultured with 150 mm NaCl. The intracellular distribution of ions after transfer to the medium containing 150 mm NaCl was analysed by isolating the vacuoles.Treatment with amiloride, an inhibitor of the Na+/H+ antiporter, suppressed the recovery of Na+ to the original level in the cells. Treatment with 150 mm NaCl for 3 d stimulated the activities of both the vanadate‐dependent H+‐ATPase and the Na+/H+ antiporter in the plasma membrane fraction.
Mercury‐induced genes in Arabidopsis thaliana: identification of induced genes upon long‐term mercuric ion exposure
Authors: Heidenreich B. , Mayer K. , Sandermann H. , Ernst D. 
Published: March 2003

AbstractMercuric‐ion‐induced gene expression was studied in Arabidopsis thaliana Columbia wild type. Rosettes of plants grown for 21 d on agar medium supplemented with 20, 30 and 40 µm HgCl2 were pooled and used to isolate cDNAs of induced genes by suppression subtractive hybridization. Of the 576 clones isolated initially, 31 turned out to be mercury‐induced by Northern hybridization. However, kinetic studies using cDNA arrays clearly showed that seven genes were exclusively mercuric‐ion‐induced, 14 were induced by mercury but also affected by a diurnal rhythm, and 10 clones were only modulated by the day–night cycle. The expression levels of the metal‐induced genes increased from 1·5‐fold to 10‐fold. Functional classification resulted in genes encoding proteins for the photosynthetic apparatus and for the antioxidative system. In addition, unexpected genes, whose connection to mercury ion stress is not evident, were identified.
Atmospheric CO2 concentration does not directly affect leaf respiration in bean or poplar
Authors: Jahnke S. 
Published: March 2003

AbstractIt is a matter of debate if there is a direct (short‐term) effect of elevated atmospheric CO2 concentration (Ca) on plant respiration in the dark. When Ca doubles, some authors found no (or only minor) changes in dark respiration, whereas most studies suggest a respiratory inhibition of 15–20%. The present study shows that the measurement artefacts – particularly leaks between leaf chamber gaskets and leaf surface, CO2 memory and leakage effects of gas exchange systems as well as the water vapour (‘water dilution’) effect on DCO2 measurement caused by transpiration – may result in larger errors than generally discussed. A gas exchange system that was used in three different ways – as a closed system in which Ca increased continuously from 200 to 4200 mmol (CO2) mol‐1 (air) due to respiration of the enclosed leaf; as an intermittently closed system that was repeatedly closed and opened during Ca periods of either 350 or 2000 mmol mol‐1, and as an open system in which Ca varied between 350 and 2000 mmol mol‐1– is described. In control experiments (with an empty leaf chamber), the respective system characteristics were evaluated carefully. When all relevant system parameters were taken into account, no effects of short‐term changes in CO2 on dark CO2 efflux of bean and poplar leaves were found, even when Ca increased to 4200 mmol mol‐1. It is concluded that the leaf respiration of bean and poplar is not directly inhibited by elevated atmospheric CO2.
Rapid, reversible alterations in spinach thylakoid appression upon changes in light intensity
Authors: Rozak P. R. , Seiser R. M. , Wacholtz W. F. , Wise R. R. 
Published: March 2003

AbstractChanges in light quantity and quality cause structural changes within the thylakoid membrane; long‐term responses have been described for so‐called ‘sun’ and ‘shade’ leaves. Many leaves, however, experience changes in irradiance on a time scale of minutes due to self‐shading and sun flecks. In this study, mature, attached spinach leaves were grown at 300 µmol photons m−2 s−1then rapidly switched to a different light treatment. The treatment irradiances were 10, 800 or 1500 µmol m−2 s−1for 10 min, or 10 or 20 min of self‐shading (about 10 µmol m−2 s−1). Image analysis of transmission electron micrographs revealed that a 10 min switch to a lower light intensity increased grana size and number per chloroplast profile by 10–20%. Returning the leaves to 300 µmol m−2 s−1for 10 min reversed the phenomenon. Chlorophyll fluorescence measurements of detached, intact leaves at 77 K were suggestive of a transition from state 2 to state 1 upon shading. Diurnal ultrastructural measurements of granal size and number did not reveal a significant net change in ultrastructure over the time scale of hours. It is concluded that spinach chloroplasts can alter the degree of thylakoid appression in response to irradiance changes on a time scale of minutes. These ultrastructural responses are caused by biochemical and biophysical adjustments within the thylakoid membrane that serve to maximize photosynthesis and minimize photo‐inhibition under rapidly fluctuating light environments.
Consequences of root growth kinetics and vascular structure on the distribution of lateral roots
Authors: Draye X. 
Published: March 2003

AbstractIt has been proposed that the acropetal initiation of lateral roots is a built‐in process specified as part of the general process of cell division and differentiation in the parent root tip. Conversely, it is commonly reported that root branching is essentially a variable feature. In the present study, the interlateral distance along the parent root has been investigated using three banana varieties (Musa spp.) grown in two substrates. The pattern of lateral root initiation was obscured by variations of root growth patterns and vascular structure among roots, genotypes and substrates. A framework model is formulated showing the influence of growth pattern and vascular structure on branching density. The model raises a distinction between growth components which should not affect the branching density (i.e. rate of cell division) and which may affect it (i.e. size of mature cells and number of transverse divisions performed by cells executing their trajectory in the meristem). It appears also that lateral root density and root growth rate might be independently modulated by appropriate changes of root growth patterns, in banana and presumably many other taxa.
Control of chemokine production at the blood–retina barrier
Authors: Crane I. J. , Wallace C. A. , Mckillop‐Smith S. , Forrester J. V. 
Published: March 2003

SummaryChemokine production at the blood–retina barrier probably plays a critical role in determining the influx of tissue‐damaging cells from the circulation into the retina during inflammation. The blood–retina barrier comprises the retinal microvascular endothelium and the retinal pigment epithelium. Chemokine expression and production by human retinal microvascular endothelial cells (REC) have never been reported previously, so we examined the in vitro expression and production of monocyte chemoattractant protein‐1 (MCP‐1), regulated on activation of normal T‐cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)‐1α, MIP‐1β, interleukin (IL)‐8, epithelial cell‐derived neutrophil activating protein‐78 (ENA‐78) and growth related oncogene α (GROα) in these cells, both unstimulated and stimulated by cytokines likely to be present during the evolution of an inflammatory response. We compared this to expression and production of these chemokines in vitro in human retinal pigment epithelial cells (RPE). MCP‐1 was expressed and produced constitutively by REC but all the chemokines were produced in greater amounts upon stimulation with the proinflammatory cytokines IL‐1β and tumour necrosis factor‐α (TNF‐α). MCP‐1 and IL‐8 were produced at much higher levels than the other chemokines tested. MIP‐1α and MIP‐1β were present only at low levels, even after stimulation with IL‐1β and TNF‐α. Cytokines with greater anti‐inflammatory activity, such as IL‐4, IL‐10, IL‐13, transforming growth factor‐β (TGF‐β) and IL‐6, had little effect on chemokine production either by REC alone or after stimulation with IL‐1β and TNF‐α. RPE, although a very different cell type, showed a similar pattern of expression and production of chemokines, indicating the site‐specific nature of chemokine production. Chemokine production by REC and RPE is probably significant in selective leucocyte recruitment during the development of inflammation in the retina.
Diversity in MHC class II antigen presentation
Authors: Robinson John H. , Delvig Alexei A. 
Published: March 2003

SummaryProcessing exogenous and endogenous proteins for presentation by major histocompatibility complex (MHC) molecules to T cells is the defining function of antigen‐presenting cells (APC) as major regulatory cells in the acquired immune response. MHC class II‐restricted antigen presentation to CD4 T cells is achieved by an essentially common pathway that is subject to variation with regard to the location and extent of degradation of protein antigens and the site of peptide binding to MHC class II molecules. These subtle variations reveal a surprising flexibility in the ways a diverse peptide repertoire is displayed on the APC surface. This diversity may have profound consequences for the induction of immunity to infection and tumours, as well as autoimmunity and tolerance.
Effects of food addition on the seasonal density‐ dependent structure of bank vole Clethrionomys glareolus populations
Authors: Yoccoz Nigel G. , Stenseth Nils ChR. , Henttonen Heikki , Prévot‐Julliard Anne‐Caroline 
Published: March 2003

Summary

Population growth rates of bank vole populations in northern Finland were studied using long‐term Capture–Mark–Recapture (CMR) data from two large grids (food‐addition and control), in 1982–94.
A marked seasonal structure was found for direct density dependence, with a stronger density dependence in summer than in other seasons. There was no detectable evidence of delayed density dependence, consistent with the disappearance of large periodic multi‐annual fluctuations.
Food‐addition resulted in higher densities whereas the effect on the seasonal density‐dependent structure was negligible.
Stability analysis of the deduced population dynamics model suggests that the dynamics were not affected by food addition. Variation in food resources is therefore unlikely to be a direct cause for multi‐annual fluctuations in the studied system. Future studies should aim at linking the seasonal structure in the variation of vital rates to the seasonal structure in population dynamics.
Role of resource availability on sex, caste and reproductive allocation ratios in the Argentine antLinepithema humile
Authors: Aron S. , Keller L. , Passera L. 
Published: March 2003

SummaryResource availability has long been recognized to influence reproductive decisions in eusocial Hymenoptera. We analysed how protein availability affects the number and the weight of worker, male and queen pupae, as well as its effect on sex, caste and reproductive allocation ratios, in the Argentine antLinepithema humileMayr. Colonies were maintained on diets with three levels of access to proteins: no protein, intermediate and high levels of proteins.There was no significant difference between the intermediate and high levels of protein in the number of queen, male and worker pupae produced. Similarly, the intermediate vs. high levels of protein treatments did not differ with regard to the weight of pupae nor the relative investments between the three castes. This suggests that, inL. humile, there could be a threshold over which additional amounts of protein have no more effect on reproductive allocation or the size of the individuals produced.The main effect of protein supplementation was to increase the number of sexual pupae (queens and males) produced. By contrast, the number of workers produced remained unaffected by the level of proteins. The higher investment in sexuals in nests supplemented with proteins resulted in a significantly higher proportion of queen pupae among females, as well as higher proportion of males among all individuals produced in these nests. However, the proportion of males among sexuals (numerical sex ratio) was not significantly different between supplemented and unsupplemented nests.Workers reacted to a higher protein diet not only by rearing more sexuals, but also by producing larger individuals of the three castes.The proportional investment allocated to queens among females was higher in the protein‐supplemented treatments. Protein‐supplemented nests also invested proportionally more into sexual production than unsupplemented nests. However, whereas increased sexual production is generally associated with a more female‐biased sex investment ratio in ants, sex allocation ratio was not significantly different between supplemented and unsupplemented nests.Overall, our results support the view that protein availability influences the proportion of brood that is culled, with workers eliminating a significant proportion of both the male and female sexual brood in unsupplemented nests.The increasing amount of experimental data showing that brood culling is an important part of the biology of ants and other social insects emphasis the need to combine kin selection and life‐history approaches to study the outcome of queen–worker conflicts on the dynamics of colony growth and sex allocation.
Intraspecific resource partitioning in brown trout: the temporal distribution of foraging is determined by social rank
Authors: Alanärä Anders , Burns Martin D. , Metcalfe Neil B. 
Published: March 2003

Summary

Animals can reduce the competition for a limiting resource by temporal segregation, whereby individuals exploit the resource at different times. However, the pay‐offs may vary predictably over time, and it can be predicted that (a) more dominant competitors should gain access to resources at the preferred times and (b) the degree of temporal segregation will vary with the intensity of competition.
Here we show experimentally that individual brown trout Salmo trutta (L.) made sequential use of foraging areas, with dominant individuals feeding mainly at the most beneficial times of dusk and the early part of the night while more subordinate fish fed at other times.
However, the degree of overlap in foraging times between high‐ranking fish was dependent on energetic demands. At low temperatures (when requirements were low) the temporal activity patterns of top‐ranking fish were synchronized, with foraging concentrated at the preferred times. In contrast, when temperature was raised to increase energetic requirements, activity patterns showed strong temporal segregation: the most dominant fish remained predominantly nocturnal, whereas second‐ranking fish became increasingly diurnal.
This is the first experimental demonstration of shifts in the daily pattern of activity caused by varying intensity of intraspecific competition.
Safe selfish sentinels in a cooperative bird
Authors: Wright J. , Berg E. , De Kort S. R. , Khazin V. , Maklakov A. A. 
Published: March 2003

SummarySentinel behaviour involves a unique cooperative system of dedicated look‐outs which protect members of their social group from attack by predators. Using detailed observations from groups of Arabian babblers,Turdoides squamiceps,we tested the original theoretical suggestion that cooperative sentinel systems are simply the result of individually selfish state‐dependent patterns of behaviour.Sentinel effort and the number of sentinel bouts per individual per hour were greater for males than females, and both increased with individual dominance status within the group.Sentinel behaviour was unaffected by group social structure, in terms of patterns of relatedness and the number of potential breeders.Total group sentinel effort increased with group size, while the effort per individual decreased irrespective of sex and dominance rank. Simultaneous sentinel behaviour by two or more birds was very rare, but increased with group size.Sentinel effort followed seasonal fluctuations in food availability, but not peaks of raptor migration through the study site.Body mass was greater for males than females and was positively related to dominance rank. Overall, body mass explained much of the variation in individual sentinel effort both within and between birds. However, data on individual foraging performance could not be related to changes in body mass and thus to differences in sentinel effort.Sentinel behaviour in groups of Arabian babblers therefore confirms many of the predictions arising from state‐dependent models of cooperative, yet individually selfish, sentinel behaviour.