bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Resource 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

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

Sentinel 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.
Seasonal decline in clutch size in European starlings: a novel randomization test to distinguish between the timing and quality hypotheses
Authors: Christians Julian K. , Evanson Melissa , Aiken Jonathan J.
Published: March 2003

The seasonal decline in clutch size observed in many avian populations may be due to (a) a causal effect of the timing of breeding or (b) variation in individual quality (i.e. lower quality individuals lay fewer eggs and lay later in the season).

To distinguish between these two hypotheses, we manipulated the timing of breeding of European starlings (Sturnus vulgaris L.) by removing first clutches to induce the production of replacement clutches. This experiment was performed at two sites over three breeding seasons.

To test whether the within‐individual trend in clutch size differed from the seasonal decline in clutch size observed in the population, we devised a novel randomization test that overcomes some of the potential limitations of previously used analyses.

We observed no within‐female decline in clutch size in any year at either site. Therefore, clutch removal did not appear to manipulate female quality (due to the costs of egg production), a potentially confounding factor in such experiments; only the timing of breeding was manipulated.

The within‐individual seasonal trend in clutch size differed significantly from the population decline in four of six cases (year–site combinations); there is good reason to believe that the lack of a significant difference in the two other cases was due to low statistical power. Thus, our data support the hypothesis that the season decline in clutch size in this species is due to variation in female quality.

The between‐year repeatability of clutch size was 0·47 and significantly different from zero, whereas that of relative laying date was much lower (−0·23) and non‐significant. The repeatability data are thus consistent with the quality hypothesis: clutch size is characteristic of individuals regardless of their timing of breeding.

Female body mass at the beginning of incubation was not related consistently to clutch size or laying date, and therefore does not appear to be an indicator of female quality in this context.
Fluorescence localization after photobleaching (FLAP): a new method for studying protein dynamics in living cells
Authors: Dunn G. A. , Dobbie I. M. , Monypenny J. , Holt M. R. , Zicha D.
Published: March 2003

FLAP is a new method for localized photo‐labelling and subsequent tracking of specific molecules within living cells. It is simple in principle, easy to implement and has a wide potential application. The molecule to be located carries two fluorophores: one to be photobleached and the other to act as a reference label. Unlike the related methods of fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP), the use of a reference fluorophore permits the distribution of the photo‐labelled molecules themselves to be tracked by simple image differencing. In effect, FLAP is therefore comparable with methods of photoactivation. Its chief advantage over the method of caged fluorescent probes is that it can be used to track chimaeric fluorescent proteins directly expressed by the cells. Although methods are being developed to track fluorescent proteins by direct photoactivation, these still have serious drawbacks. In order to demonstrate FLAP, we have used nuclear microinjection of cDNA fusion constructs of β‐actin with yellow (YFP) and cyan (CFP) fluorescent proteins to follow both the fast relocation dynamics of monomeric (globular) G‐actin and the much slower dynamics of filamentous F‐actin simultaneously in living cells.
Automated high‐throughput electron tomography by pre‐calibration of image shifts
Authors: Ziese U. , Janssen A. H. , Murk J.‐L. , Geerts W. J. C. , Van der Krift T. , Verkleij A.J. , Koster A.J.
Published: March 2003

Electron tomography is a versatile method for obtaining three‐dimensional (3D) images with transmission electron microscopy. The technique is suitable to investigate cell organelles and tissue sections (100–500 nm thick) with 4–20 nm resolution. 3D reconstructions are obtained by processing a series of images acquired with the samples tilted over different angles. While tilting the sample, image shifts and defocus changes of several µm can occur. The current generation of automated acquisition software detects and corrects for these changes with a procedure that incorporates switching the electron optical magnification. We developed a novel method for data collection based on the measurement of shifts prior to data acquisition, which results in a five‐fold increase in speed, enabling the acquisition of 151 images in less than 20 min. The method will enhance the quality of a tilt series by minimizing the amount of required focus‐change compensation by aligning the optical axis to the tilt axis of the specimen stage. The alignment is achieved by invoking an amount of image shift as deduced from the mathematical model describing the effect of specimen tilt. As examples for application in biological and materials sciences 3D reconstructions of a mitochondrion and a zeolite crystal are presented.
Calcium‐induced Cytochrome c release from CNS mitochondria is associated with the permeability transition and rupture of the outer membrane
Authors: Brustovetsky Nickolay , Brustovetsky Tatiana , Jemmerson Ronald , Dubinsky Janet M.
Published: March 2003

The mechanisms of Ca2+‐induced release of Cytochrome c (Cyt c) from rat brain mitochondria were examined quantitatively using a capture ELISA. In 75 or 125 mm KCl‐based media 1.4 µmol Ca2+/mg protein caused depolarization and mitochondrial swelling. However, this resulted in partial Cyt c release only in 75 mm KCl. The release was inhibited by Ru360, an inhibitor of the Ca2+ uniporter, and by cyclosporin A plus ADP, a combination of mitochondrial permeability transition inhibitors. Transmission electron microscopy (TEM) revealed that Ca2+‐induced swelling caused rupture of the outer membrane only in 75 mm KCl. Koenig's polyanion, an inhibitor of mitochondrial porin (VDAC), enhanced swelling and amplified Cyt c release. Dextran T70 that is known to enhance mitochondrial contact site formation did not prevent Cyt c release. Exposure of cultured cortical neurons to 500 µm glutamate for 5 min caused Cyt c release into the cytosol 30 min after glutamate removal. MK‐801 or CsA inhibited this release. Thus, the release of Cyt c from CNS mitochondria induced by Ca2+in vitro as well as in situ involved the mPT and appeared to require the rupture of the outer membrane.
A link between maze learning and hippocampal expression of neuroleukin and its receptor gp78
Authors: Luo Yongquan , Long Jeffery M. , Lu Chengbiao , Chan Sic L. , Spangler Edward L. , Mascarucci Paolo , Raz Avraham , Longo Dan L. , Mattson Mark P. , Ingram Donald K. , Weng Nan‐ping
Published: March 2003

Neuroleukin (NLK) is a multifunctional protein involved in neuronal growth and survival, cell motility and differentiation, and glucose metabolism. We report herein that hippocampal expression of NLK and its receptor gp78 is associated with maze learning in rats. First, mRNA levels of NLK and gp78 were significantly increased in hippocampi of male Fischer‐344 rats following training in the Stone T‐maze and the Morris water maze. Second, a parallel increase was found in hippocampal NLK and gp78 proteins after maze learning. Third, NLK and gp78 mRNA and protein expression in hippocampus was reduced in a group of aged rats that showed more errors during the acquisition of the Stone maze task as compared with young rats. Finally, application of recombinant NLK to hippocampal neurons significantly enhanced glutamate‐induced ion currents, functional molecular changes that have been correlated with learning in vivo. Taken together, our results identify a novel association of hippocampal expression of NLK and its receptor gp78 with rat maze learning. Interaction of NLK with gp78 and subsequent signaling may strengthen synaptic mechanisms underlying learning and memory formation.
Increased mitochondrial antioxidative activity or decreased oxygen free radical propagation prevent mutant SOD1‐mediated motor neuron cell death and increase amyotrophic lateral sclerosis‐like transgenic mouse survival
Authors: Liu Rugao , Li Baolin , Flanagan Shawn W. , Oberley Larry W. , Gozal David , Qiu Mengsheng
Published: March 2003

The molecular mechanisms of selective motor neuron degeneration in human amyotrophic lateral sclerosis (ALS) disease remain largely unknown and effective therapies are not currently available. Mitochondrial dysfunction is an early event of motor neuron degeneration in transgenic mice overexpressing mutant superoxide dismutase (SOD)1 gene and mitochondrial abnormality is observed in human ALS patients. In an in vitro cell culture system, we demonstrated that infection of mouse NSC‐34 motor neuron‐like cells with adenovirus containing mutant G93A‐SOD1 gene increased cellular oxidative stress, mitochondrial dysfunction, cytochrome c release and motor neuron cell death. Cells pretreated with highly oxidizable polyunsaturated fatty acid elevated lipid peroxidation and synergistically exacerbated motor neuron‐like cell death with mutant G93A‐SOD1 but not with wild‐type SOD1. Similarly, overexpression of mitochondrial antioxidative genes, MnSOD and GPX4 by stable transfection significantly increased NSC‐34 motor neuron‐like cell resistance to mutant SOD1. Pre‐incubation of cells with␣spin trapping molecule, 5′,5′‐dimethylpryrroline‐N‐oxide (DMPO), prevented mutant SOD1‐mediated mitochondrial dysfunction and cell death. Furthermore, treatment of mutant G93A‐SOD1 transgenic mice with DMPO significantly delayed paralysis and increased survival. These findings suggest a causal relationship between enhanced oxidative stress and mutant SOD1‐mediated motor neuron degeneration, considering that enhanced oxygen free radical production results from the SOD1 structural alterations. Molecular approaches aimed at increasing mitochondrial antioxidative activity or effectively blocking oxidative stress propagation can be potentially useful in the clinical management of human ALS disease.
Neurotoxic mechanisms triggered by Alzheimer's disease‐linked mutant M146L presenilin 1: involvement of NO synthase via a novel pertussis toxin target
Authors: Hashimoto Yuichi , Ito Yuko , Arakawa Erika , Kita Yoshiko , Terashita Kenzo , Niikura Takako , Nishimoto Ikuo
Published: March 2003

While it has been reported that familial Alzheimer's disease (FAD)‐linked mutants of amyloid precursor protein (APP) and presenilin (PS)2 induce neuronal cytotoxicity in a manner sensitive to antioxidant and pertussis toxin (PTX), little of the mechanism for PS1‐mediated neuronal cell death has been characterized. We previously found that multiple mechanisms, different in detail, underlie cytotoxicities by two FAD‐linked mutants of APP, using neuronal cells with an ecdysone‐controlled expression system. Here we report that this system revealed that (i) low expression of FAD‐linked M146L‐PS1 caused neuronal cell death, whereas that of wild‐type (wt)PS1 did not; (ii) mutation‐specific cytotoxicity by M146L‐PS1 was sensitive to antioxidant glutathione‐ethyl‐ester and resistant to Ac‐DEVD‐CHO; (iii) cytotoxicity by higher expression of wtPS1 was resistant to both; and (iv) cytotoxicity by M146L‐PS1 was inhibited by PTX. It was also highly likely that the involved superoxide‐generating enzyme was nitric oxide synthase (NOS), and that the PTX‐sensitive cytotoxic signal by M146L‐PS1 was mediated by none of the Gi/o proteins. We conclude that M146L‐PS1 activates a NOS‐mediated cytotoxic pathway via a novel PTX target.
PC12nnr5cells expressing TrkA receptors undergo morphological but not cholinergic phenotypic differentiation in response to nerve growth factor
Authors: Baskey Jacqueline C. , Kalisch Bettina E. , Davis Wanda L. , Meakin Susan O. , Rylett R. Jane
Published: March 2003

We investigated mechanisms underlying nerve growth factor‐mediated morphological differentiation and expression of cholinergic neuronal phenotype. In PC12, but not PC12nnr5cells, nerve growth factor induces neurite‐like outgrowths and enhances cholinergic phenotype; stable expression of TrkA receptors in nnr5 cells (called B5P cells) restores morphological differentiation but not expression of choline acetyltransferase. Transfection with an AP‐1 luciferase reporter gene revealed that PC12 but not B5P cells expressed nerve growth factor‐induced functional AP‐1 activity. RT‐PCR analysis of nerve growth factor‐mediated changes in AP‐1 transcription factors showed rapid increases inc‐fosandjunBmRNA in PC12 and B5P cells, while increases inc‐junwere small. Using DNA–protein gel shift assays we determined that nerve growth factor stimulates AP‐1 binding in both PC12 and B5P cells, and identified c‐Fos, FosB, Fra‐1, Fra‐2, c‐Jun, JunB and JunD in AP‐1 complexes. In Fos/Jun functional luciferase reporter assays, nerve growth factor stimulated phosphorylation of c‐Fos in both PC12 and B5P cells, but phosphorylation of c‐Jun only in PC12, and not in B5P cells. These data indicate that mechanisms relating to AP‐1 transcription factor complexes underlying nerve growth factor‐mediated enhancement of cholinergic gene expression may differ from those required for morphological differentiation.
Molecular determinants for the differential coupling of Gα16 to the melatonin MT1, MT2 and Xenopus Mel1c receptors
Authors: Lai Frank P. L. , Mody Sejal M. , Yung Lisa Y. , Kam Jason Y. M. , Pang Celia S. , Pang Shiu F. , Wong Yung H.
Published: March 2003

The pineal neurohormone melatonin modulates a variety of physiological processes through different receptors. It has recently been reported that the cloned melatonin receptors (MT1, MT2 and Mel1c) exhibit differential abilities to stimulate phospholipase C (PLC) via G16. Here we examined the molecular basis of such differences in melatonin receptor signaling. Coexpression of MT1 or MT2 with the α subunit of G16 (Gα16) allowed COS‐7 cells to accumulate inositol phosphates in response to 2‐iodomelatonin. In contrast, Mel1c did not activate Gα16 even though its expression was demonstrated by radioligand binding and agonist‐induced inhibition of adenylyl cyclase. As Mel1c possesses an exceptionally large C‐terminal tail, we further asked if this structural feature prevented productive coupling to Gα16. Eleven chimeric melatonin or mutant receptors were constructed by swapping all or part of the C‐terminal tail between MT1, MT2 and Mel1c. All chimeras were fully capable of binding 2‐[125I]iodomelatonin and inhibiting adenylyl cyclase. Chimeras containing the full‐length Mel1c tail were incapable of activating Gα16, while those that contained the complete C‐terminal region of either MT1 or MT2 stimulated PLC. Incorporation of the extra portion of the C‐terminal tail of Mel1c to either MT1 or MT2 completely abolished the chimeras' ability to stimulate PLC via Gα16. In contrast, trunc‐ ation of the C‐terminal tail of Mel1c allowed interaction with Gα16. Our results suggest that Gα16 can discern structural differences amid the three melatonin receptors and provide evidence for functional distinction of Mel1c from MT1 and MT2 receptors.
The molecular and genetic basis of pollen–pistil interactions
Authors: Wheeler M. J. , Franklin‐Tong V. E. , Franklin F. C. H.
Published: March 2003

Over the past decade or so, there has been significant progress towards elucidating the molecular events occurring during pollination in flowering plants. This process involves a series of complex cellular interactions that culminates in the fusion between male and female gametes. The process also regulates crucial events such as pollen adhesion, hydration, pollen tube growth and guidance to the ovules. Additionally, in many instances, incompatibility mechanisms that control the acceptance or rejection of pollen alighting on a recipient plant play a major role in the pollination process. In this article we aim to review our current understanding of the components that are implicated in enabling the pollen to deliver the male gametes to the ovary and the molecular mechanisms by which they are thought to act.

Contents

Summary
565

I.
Introduction
565

II.
Adhesion of pollen to the stigma
566

III.
Pollen hydration
567

IV.
Pollen germination and initial growth on the stigma surface
568

V.
Pollen tube growth through the style and pollen tube guidance
569

VI.
Control of pollen viability by incompatibility responses
572

1. Self incompatibility (SI)
573

Gametophytic SI
573

SI in the Solanaceae
573

SI in Papaver
575

Sporophytic SI
577

SI in Brassica
577

SI in Ipomoea
579

2. Interspecific incompatibility responses
579

VII.
Conclusions and perspective
580

References
580
Ozone exposure affects photosynthesis of pumpkin (Cucurbita pepo) plants
Authors: Castagna A. , Nali C. , Ciompi S. , Lorenzini G. , Soldatini G. F. , Ranieri A.
Published: March 2003

Physiological and biochemical responses of the ozone (O3)‐sensitive pumpkin cultivar (Cucurbita pepo‘Ambassador’) to O3 exposure are reported here to determine critical O3 concentrations related to duration of pollutant exposure.

Pumpkin plants were exposed to 150 nl l−1 of O3 for 5 h d−1 for 5 d. Gas‐exchange, chlorophyll a fluorescence and pigment‐content measurements were determined on days 1, 3, 5 for young leaves and days 1, 3, 4 for the mature leaves of control and treated plants.

In both young and mature leaves, O3 induced a significant decrease in photosynthetic rate through impacts on stomata and photochemistry. A reduction in PSII photochemistry, photochemical quenching and quantum yield, accompanied by a parallel increase in nonphotochemical quenching was detected. Following O3 treatment the pool of xanthophyll cycle pigments and the de‐epoxidation index underwent a significant increase, whereas chlorophylls and β‐carotene were less affected.

The results showed that most of the parameters were affected by O3 after 1 d of exposure and indicated an overall effect of O3 and days of treatment, irrespective of leaf age.
Why is there so little research into the cell biology of the secondary vascular system of trees?
Authors: Chaffey Nigel
Published: March 2003

Despite new techniques for studying the cell biology of plant development in recent years, the secondary vascular system has been neglected. Why is this? Here it is argued that some of the barriers that have prevented more widespread study of the tree secondary vascular system are no longer valid. Some of the more intriguing aspects of the secondary vascular system include the recent discovery of a putative plant muscle and identification of a cytoskeleton‐facilitated three‐dimensional symplasmic transport pathway that permeates the tree. There are great merits in the recently adopted model tree species, poplar, and a new model system – wood formation in Arabidopsis. The time is now right for much greater exploitation of the possibilities that exist for study of the secondary vascular system of trees.
Role of fluids in the metamorphism of the Alpine Fault Zone, New Zealand
Authors: Vry J. K. , Storkey A. C. , Harris C.
Published: March 2003

Models of fluid/rock interaction in and adjacent to the Alpine Fault in the Hokitika area, South Island, New Zealand, were investigated using hydrogen and other stable isotope studies, together with field and petrographic observations. All analysed samples from the study area have similar whole‐rock δD values (δDWR = −56 to −30‰, average = −45‰, n = 20), irrespective of rock type, degree of chloritization, location along the fault, or across‐strike distance from the fault in the garnet zone. The green, chlorite‐rich fault rocks, which probably formed from Australian Plate precursors, record nearly isothermal fluid/rock interaction with a schist‐derived metamorphic fluid at high temperatures near 450–500°C (δD of water in equilibrium with the green fault rocks (δDH2O, green) ≈ −18‰; δD of water in equilibrium with the greyschists and greyschist‐derived mylonites (δDH2O, grey) ≈ −19‰ at 500°C; δDH2O, green ≈ −17‰; δDH2O, grey ≈ −14‰ at 450°C). There is no indication of an influx of a meteoric or mantle‐derived fluid in the Alpine Fault Zone in the study area. The Alpine Fault Zone at the surface shows little evidence of late‐stage retrogression or veining, which might be attributed to down‐temperature fluid flow. It is probable that prograde metamorphism in the root zone of the Southern Alps releases metamorphic fluids that at some region rise vertically rather than following the trace of the Alpine Fault up to the surface, owing to the combined effects of the fault, the disturbed isotherms under the Southern Alps, and the brittle–ductile transition. Such fluids could mix with meteoric fluids to deposit quartz‐rich, possibly gold‐bearing veins in the region c. 5–10 km back from the fault trace. These results and interpretations are consistent with interpretations of magnetotelluric data obtained in the South Island GeopHysical Transects (SIGHT) programme.
Computer experiments to investigate complex fibre patterns in natural antitaxial strain fringes
Authors: Koehn D. , Aerden D. G. A. M. , Bons P. D. , Passchier C. W.
Published: March 2003

Antitaxial non‐deforming strain fringes from Lourdes, France, show complex quartz, calcite and chlorite fibre patterns that grew around pyrite in a slate during non‐coaxial progressive deformation. Development of these fringes was modelled using a computer program ‘Fringe Growth 2.0’ which can simulate incremental growth of crystal fibres around core‐objects of variable shape. It uses object‐centre paths as input, which are obtained from fibre patterns in thin section. The numerical experiments produced fibre patterns that show complex intergrowth of displacement‐controlled, face‐controlled and intermediate fibres similar to those in the natural examples. The direction of displacement‐controlled growth is only dependent on the relative movement between core‐object and fringe, so that core‐object rotation with respect to the fringe influences the fibre patterns and produces characteristic asymmetric fibre curvature. Object‐centre paths should be used for kinematic analysis of strain fringes instead of single fibres since these paths represent the fringe as a whole. The length along the path can be interpreted in terms of finite strain and path curvature in terms of rigid body rotation of fringes with respect to an external reference frame.
Linking procedural and conceptual mathematical knowledge through CAL
Authors: Kadijevich DJ. , Haapasalo L.
Published: March 2003

Abstract Despite its high educational relevance, relatively few CAL studies have examined whether their computer‐based treatments search for and/or utilise any potential link between procedural and conceptual mathematical knowledge. This paper summarises some of the findings of studies of this kind, explains how these knowledge types may be linked and proposes two constructivist CAL environments which enable a desired link.
Evolving open learning environments using hypermedia technology
Authors: Trikić A.
Published: March 2003

Abstract A number of features of web‐based hypermedia are identified as providing a suitable medium for the design of open learning environments. The underlying object‐oriented architecture of hypermedia systems accords with the need for representational diversity of pedagogic mechanisms and the ongoing re‐construction that an evolutionary approach to the design of learning activity demands. A web‐based prototype has been constructed to represent aspects of the National English Board curriculum in diabetes mellitus. The design and development process tries to take account of features of the environment likely to influence or be influenced by the intervention. Quantitative and qualitative methods have been employed to enable an evaluation of the hypermedia design and its environment of use.
Allozyme relationships among ten species of Rhodniini, showing paraphyly of Rhodnius including Psammolestes
Authors: Monteiro F. A. , Lazoski C. , Noireau F. , Solé‐Cava A. M.
Published: March 2003

Abstract Genetic relationships among 10 species of bugs belonging to the tribe Rhodniini (Hemiptera: Reduviidae), including some important vectors of Chagas disease, were inferred from allozyme analysis of 12 enzyme loci (out of 21 enzyme systems examined), using agarose gel electrophoresis. These species formed two clusters: one comprising Rhodnius brethesi, R. ecuadoriensis, R. pallescens and R. pictipes; the other with Psammolestes tertius, Rhodnius domesticus and the Rhodnius prolixus group comprising R. nasutus, R. neglectus, R. prolixus and R. robustus.

The resulting tree was [((R. ecuadoriensis, R. pallescens) R. brethesi) R. pictipes], [R. domesticus (P. tertius{(R. nasutus, R. neglectus) (R. prolixus, R. robustus)})]. Rhodnius nasutus and R. neglectus differed by only one locus, whereas no diagnostic loci were detected between R. prolixus and R. robustus (22 loci were analysed for these four species), despite considerable DNA sequence divergence between species in each of these pairs. Allozymes of the R. prolixus group showed greater similarity with Psammolestes tertius than with other Rhodnius spp., indicating that Rhodnius is paraphyletic and might include Psammolestes.
Accumulation of calbindin in cortical pyramidal cells with ageing; a putative protective mechanism which fails in Alzheimer's disease
Authors: Greene J. R. T. , Radenahmad N. , Wilcock G. K. , Neal J. W. , Pearson R. C. A.
Published: March 2003

There is considerable interest in the status of calbindin immunoreactive neurones in Alzheimer's disease (AD) but previous studies have produced widely differing results. Here we describe calbindin neurones in temporal neocortex from 18 severely demented patients with neuropathologically confirmed AD and 13 age and post‐mortem delay matched, neurologically normal controls. Calbindin immunoreactive neurones were small and round in layers II–IV, and pyramidal in layers IIIc and V. There were significantly more calbindin positive neurones in controls than in AD (mean± SD, for each comparison P < 0.01): superior temporal lobe, AD = 3.32 ± 2.24, Control (C) = 24.83 ± 10.8; middle temporal lobe, AD = 3.6 ± 4.94, C = 26.09 ± 15.7; inferior temporal lobe, AD 3.69 ± 3.6, C = 25.25 ± 16.9. Furthermore, there was an age‐related increase in immunopositive neurones in the superior (r2 = 0.37, P = 0.046) and inferior (r2 = 0.75, P = 0.01) temporal gyri in controls. In AD the number of calbindin positive neurones did not change with age. This is the first report of such an age‐related increase in controls, and it suggests that this, rather than a decrease in AD, accounts for the overall difference between AD and controls. It is possible that an increase in intraneuronal calbindin protects these cells from degeneration and that failure of such a neuroprotective mechanism is a significant contributory factor in the pathogenesis of AD.
Control of the flexible annual/biennial life cycle of the heather psyllid Strophingia ericae
Authors: Butterfield J. , Whittaker J. B. , Fielding C. A.
Published: March 2003

Abstract. Strophingia ericae (Curtis) (Homoptera: Psylloidea) takes one or two years to complete its life cycle. In both cases eggs hatch over a prolonged period from midsummer, possibly extending into the following spring at high altitude, and instars overlap in time. Instar III is the predominant overwintering stage in the lowland, annual cycle, whereas in the upland, biennial cycle most first‐year nymphs overwinter in instars I and II and most second‐year nymphs in instar V. When moved to the laboratory, instars IV and V from a predominantly annual population showed accelerated development in response to elevated temperatures and to long days in both mid‐winter and early spring. In the biennial life cycle, short autumn days retard instar V development but the response to photoperiod disappears by the end of winter. Exposure to LD 18 : 6 h retarded development of early instars in the annual population, resulting in an accumulation in instar III. The proportion of overwintering instars I and II rises with increase in altitude and moult to instar III becomes progressively delayed. Nymphs that reach instar III under long daylengths in the year following hatching are channelled towards the biennial cycle. Exposure of a predominantly biennial population to 15 °C and LD 18 : 6 h after midsummer, thus avoiding autumn conditions, promoted the rapid development of overwintered nymphs, switching the cycle from biennial to annual.
A phylogenetic analysis of the Neotropical riodinid butterfly generaJuditha,Lemonias,ThisbeandUraneis, with a revision ofJuditha(Lepidoptera: Riodinidae: Nymphidiini)
Authors: Hall Jason P. W. , Harvey Donald J.
Published: March 2003

Abstract.A cladistic analysis is presented for all twenty‐four species in the Neotropical riodinid butterfly generaJudithaHemming,LemoniasHübner,ThisbeHübner andUraneisBates based on sixty‐nine characters of male and female morphology and external facies, and utilizingAudre dominaBates as the outgroup. All characters are illustrated. The analysis confirms the monophyly ofJudithaandUraneis, but indicates thatLemoniasis polyphyletic andThisbeis paraphyletic with respect toUraneis, leading us to synonymizeUraneiswithThisbe(syn.n.).Judithais found to be the sister clade to trueLemonias+ (Thisbe+Uraneis). A revision ofJudithais presented which includes discussions on the taxonomy, biology and distribution of its species, and illustrations of the adults and male and female genitalia of all taxa and the early stages of an exemplar,J. caucana. Eight species are recognized inJuditha, including two,J. nazaandJ. inambari, which are described as new. The following new generic combinations are made:rubigoBates is transferred fromJudithatoPachythoneBates;agaveGodman & Salvin andleucogoniaStichel are transferred fromLemoniastoPseudonymphidiaCallaghan;ochraceaMengel,theodoraGodman andalbofasciataGodman are transferred fromAudreHemming toLemonias;fenestrellaLathy is transferred fromThisbetoSynargisHübner;hyalinaButler,ucubisHewitson andincubusHall, Lamas & Willmott are transferred fromUraneistoThisbe;andoditesCramer (=phylleusAuctt.) is transferred fromSynargistoJuditha(comb.n.).
Immunobiology of liver dendritic cells
Authors: Thomson Angus W , O'Connell Peta J , Steptoe Raymond J , Lu Lina
Published: March 2003

Dendritic cells (DC) are rare, bone marrow‐derived antigen‐presenting cells that play a critical role in the induction and regulation of immune reactivity. In this article, we review the identification and characterization of liver DC, their ontogenic development, in vivo mobilization and population dynamics. In addition, we discuss the functions of DC isolated from liver tissue or celiac lymph, or propagated in vitro from liver‐resident haemopoietic stem/progenitor cells. Evidence concerning the role of DC in viral hepatitis, liver tumours, autoimmune liver diseases, granulomatous inflammation and the outcome of liver transplantation is also discussed.
Hypoallergenic derivatives of major grass pollen allergens for allergy vaccination
Authors: Singh Mohan B , Bhalla Prem L
Published: March 2003

Grass pollen‐induced hay‐fever and allergic asthma represent a major health problem in industrialized countries. Whereas the symptoms of these allergic conditions can be controlled by pharmacotherapy, specific immunotherapy vaccination is the only causative approach towards the treatment of these type 1 allergies. Specific immunotherapy is based on administration of increasing amounts of the disease‐causing allergens in the form of allergen‐containing extracts. However, the extracts used for immunotherapy consist of allergenic and non‐allergenic components and may induce severe anaphylactic side‐effects upon therapeutic administration. With recent developments in molecular biology of pollen allergens it has become feasible to produce modified hypoallergenic derivatives of recombinant allergens with abrogated or greatly reduced likelihood of anaphylactic side‐effects as compared to extract‐based treatments. We have demonstrated this concept through reducing the anaphylactic potential of major rye grass pollen allergens by introducing a few point mutations which leave the overall structural fold of the molecule unaltered. These modified forms are expected to make allergen‐specific immunotherapy more widely used in the future.
Influences of orthodontic appliances on oral populations of mutans streptococci
Authors: Jordan C. , LeBlanc D. J.
Published: March 2003

A study was conducted to assess the influence of fixed appliances on the mutans streptococcal in a group of patients receiving orthodontic treatment. Mutans streptococcal counts in stimulated saliva of 27 patients were obtained at baseline, and at 1‐month intervals for 4 months. The difference in mutans streptococcal counts at baseline and at the 4‐month sampling was less than an order of magnitude in 18 of the patients, between 1 and 2 orders of magnitude in eight of the patients, and 3 orders of magnitude in one patient. Restriction endonuclease digests of genomic DNA from representative mutans streptococci isolates taken from baseline and 4‐month saliva samples, as well as from 4‐month tooth and appliance surfaces, were examined by pulsed field gel electrophoresis, after restriction endonuclease digestion. Results of the DNA banding patterns associated with isolates from 19 patients showed that, for 12 patients, all isolates examined represented the same clone of Streptococcus mutans, whereas for six patients two different S. mutans clones were detected. One patient yielded three different clones of S. mutans. A much larger number of baseline, as well as post‐appliance, isolates will have to be examined from each patient in future studies, in order to determine if the number of different S. mutans clones harbored by individual patients is related to orthodontic treatment.
The aetiology and management of irritant diaper dermatitis
Authors: Atherton D J
Published: March 2003

Irritant diaper dermatitis (IDD) is a common condition caused by the combination of wearing diapers, and incontinence of urine and faeces. The available evidence suggests that maceration of the stratum corneum by water increases susceptibility to frictional damage, and epidermal permeation of irritants. The most important irritants underlying IDD appear to be digestive enzymes persisting in faeces, particularly when these are activated by a high pH.
Cutaneous tolerance of baby wipes by infants with atopic dermatitis, and comparison of the mildness of baby wipe and water in infant skin
Authors: Ehretsmann C , Schaefer P , Adam R
Published: March 2003

To confirm the safety and cutaneous tolerability of a new brand of baby wet wipes, we conducted the following clinical studies: (i) a double‐blind in‐use study in 102 infants over a period of 2 weeks, to compare skin tolerance of the wipes vs. water and a cleansing material (ii) a chamber scarification test on adults to assess the skin irritation potential of the baby wipe, and (iii) a 4‐week clinical in‐use study in 60 babies with atopic dermatitis, to confirm safety and skin tolerability in a sensitive skin subpopulation. In the clinical comparison with water and cleansing material, skin conditions were assessed visually for presence and severity of erythema and diaper dermatitis. The overall skin condition was not different in the group using wipes and in the group using only water and a cleansing material, indicating comparable skin mildness for both regimes. The chamber scarification test confirmed that the lotion contained in the wipe has a very low irritation potential, lower than that of a currently marketed baby wipe and comparable to that of water under occlusive patch test conditions. The good skin tolerance of the wipes was supported by the observations of a dermatologist in the clinical study in babies with atopic dermatitis. These data strongly support the suitability of the baby wipes tested in these studies for daily cleansing of the diapered area, even for infants with sensitive skin. These data also provide useful information regarding the comparative skin mildness of baby wipes and water.
Current issues in antimicrobial therapy for the treatment of acne
Authors: Leyden JJ
Published: March 2003

This review summarizes current information regarding the use of antimicrobial agents for the treatment of patients with inflammatory acne. A number of drugs have been used effectively as topical or systemic therapy, often in combination with benzoyl peroxide or a retinoid. Propionibacterium acnes exhibits high in vitro sensitivity to a wide range of antimicrobials, including ampicillin, clindamycin, erythromycin, tetracycline, doxycycline, nadifloxacin, ofloxacin, minocycline, cephalexin, and gentamycin. However, not all of these drugs are equally effective in penetrating the lipid‐filled microcomedo and reducing numbers of P. acnes in the skin. Antimicrobial therapy, particularly systemic treatment, may be complicated by the potential for drug–drug interactions. Historically, the potential for antimicrobials to reduce the effectiveness of oral contraceptives has been a concern in the treatment of acne. However, there is evidence to suggest that such an interaction does not take place in patients being treated with the antimicrobials most often used in dermatological practice. Antimicrobial therapy for acne has also been complicated by the emergence of antibiotic‐resistant strains of P. acnes. Increasing P. acnes resistance can be combated by judicious use of retinoids in combination with antibiotics to reduce inflammation and infection, and employment of retinoids for maintenance therapy.
Evaluation of prenatal ultrasound diagnosis of fetal abdominal wall defects by 19 European registries
Authors: Barisic I. , Clementi M. , Häusler M. , Gjergja R. , Kern J. , Stoll C.
Published: March 2003

Objectives

To evaluate the current effectiveness of routine prenatal ultrasound screening in detecting gastroschisis and omphalocele in Europe.

Design

Data were collected by 19 congenital malformation registries from 11 European countries. The registries used the same epidemiological methodology and registration system. The study period was 30 months (July 1st 1996–December 31st 1998) and the total number of monitored pregnancies was 690 123.

Results

The sensitivity of antenatal ultrasound examination in detecting omphalocele was 75% (103/137). The mean gestational age at the first detection of an anomaly was 18 ± 6.0 gestational weeks. The overall prenatal detection rate for gastroschisis was 83% (88/106) and the mean gestational age at diagnosis was 20 ± 7.0 gestational weeks. Detection rates varied between registries from 25 to 100% for omphalocele and from 18 to 100% for gastroschisis. Of the 137 cases of omphalocele less than half of the cases were live births (n = 56; 41%). A high number of cases resulted in fetal deaths (n = 30; 22%) and termination of pregnancy (n = 51; 37%). Of the 106 cases of gastroschisis there were 62 (59%) live births, 13 (12%) ended with intrauterine fetal death and 31 (29%) had the pregnancies terminated.

Conclusions

There is significant regional variation in detection rates in Europe reflecting different policies, equipment and the operators' experience. A high proportion of abdominal wall defects is associated with concurrent malformations, syndromes or chromosomal abnormalities, stressing the need for the introduction of repeated detailed ultrasound examination as a standard procedure. There is still a relatively high rate of elective termination of pregnancies for both defects, even in isolated cases which generally have a good prognosis after surgical repair. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Color Doppler sonography of the lateral thoracic (breast‐feeding) arteries: a new approach to the diagnosis of breast disease?
Authors: Obwegeser R. , Berghammer P. , Lorenz K. , Auerbach L. , Kubista E.
Published: March 2003

Objective

The main arteries to the breast are the lateral thoracic artery and to a lesser extent the internal thoracic artery. In this prospective open diagnostic study involving 94 women, we compared the intraindividual differences of Doppler indices in the lateral thoracic (breast‐feeding) artery of breasts affected by cancer with those unaffected by disease.

Methods

Sixty‐seven consecutive patients were recruited from an outpatient unit for breast surgery and 27 volunteers were studied who were known to be without any breast disease (controls). In each patient we attempted to obtain Doppler indices from the lateral thoracic artery of both breasts. The difference in Doppler indices in each individual was assessed and statistical analysis was performed to assess whether these differences were significantly altered in women with cancer compared to healthy women.

Results

Lateral thoracic arteries could be visualized in 88% of the study population. Significantly lower values for pulsatility and resistance indices and systolic/diastolic ratios were obtained in the lateral thoracic arteries of breasts affected by cancer as compared to the contralateral breasts (1.73 ± 0.39 vs. 2.05 ± 0.47, P = 0.003; 0.78 ± 0.06 vs. 0.84 ± 0.06, P < 0.0001; 4.71 ± 1.24 vs. 6.75 ± 3.38, P = 0.0008, respectively). Using the intraindividual difference of pulsatility index, resistance index and systolic/diastolic ratio to screen for malignancy, sensitivities for breast cancer of 78%, 85% and 83%, respectively, were achieved. Depending on the cut‐off level, specificity reached 94%.

Conclusion

The intraindividual difference in Doppler indices in women with breast cancer may be a useful test for the diagnosis of breast lesions. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology