bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population genetic structure of three pond‐inhabiting Daphnia species on a regional scale (Flanders, Belgium)
Authors: Michels Erik , Audenaert Elke , Ortells Raquel , Luc De Meester  
Published: September 2003

Summary1. Only a few studies have compared patterns of genetic variation among populations of different Daphnia species on a regional scale. The present study addresses this gap and examines the relationship between diversity as revealed by allozyme variation and habitat size for populations of Daphnia pulex, D. obtusa and D. curvirostris in Flanders (Belgium). In addition, we examined whether patterns of isolation‐by‐distance could be observed in each of these three Daphnia species.2. The relationship between genetic diversity and habitat size varied among Daphnia species that occur in the same region. In D. pulex and D. obtusa populations, a positive relationship between local genetic diversity and habitat size was found, whereas the relationship was negative in D. curvirostris populations.3. Regional genetic diversity was lower than expected from patterns of local genetic diversity in D. pulex and D. obtusa populations in Flanders. This suggests that the subdivision of local Daphnia populations in a region did not obviously increase genetic diversity.4. Genetic differentiation among populations of these three species in Flanders was moderate and comparable with values observed in other Daphnia species. Patterns of isolation‐by‐distance could be observed, but the scatter was high (D. pulex) or the slope was very low (D. obtusa).
Seasonal variation in pigmentation of the dinoflagellate Peridinium gatunense (Dinophyceae) in Lake Kinneret, Israel
Authors: Yacobi Y. Z. 
Published: September 2003

Summary1. Pigment composition was measured in natural phytoplankton samples from Lake Kinneret, Israel. From March through June 1998, the dinoflagellate Peridinium gatunense Nygaard mostly contributed more than 95% of the algal biomass. Peak densities were found in April, close to the water surface, with >109 cells m−3, chlorophyll (Chl) a concentration of 380 mg m−3 and areal Chl‐a density of >1300 mg m−2.2. Cellular concentrations of Chl‐a changed between 201 and 282 pg cell−1, but did not show a defined temporal fluctuation.3. The mass ratio of Chl‐c to Chl‐a changed from March to June between 0.16 and 0.22, and the peridinin to Chl‐a ratio changed from 0.25 to 0.41. Neither ratio showed a clear pattern of seasonal change. Conversely, there was a progressive increase in diadinoxanthin and β‐carotene ratios to Chl‐a through the season, parallel to the increase in photon flux impinging upon the lake surface. The diadinoxanthin to Chl‐a ratio changed from 0.11 to 0.28 and the β‐carotene to Chl‐a ratio varied from 0.03 to 0.08 from March through June.4. Diatoxanthin was not detected in natural samples. However, it was present in experiments with P. gatunense cultures, when concentration of diatoxanthin increased rapidly, concurrent with a decrease in diadinoxanthin and β‐carotene concentrations, while Chl‐c and peridinin ratios to Chl‐a were almost stable with photon flux increase.5. The seasonal variation in cellular pigmentation of P. gatunense in Lake Kinneret suggests that accumulation of photoprotective pigments is essential for optimisation of photosynthetic activity of this large dinoflagellate.
Breaking the Non‐Responsiveness of C57BL/6 Mice to the Malarial Antigen EB200 – The Role of Carrier and Adjuvant Molecules
Authors: Rahman Q. K. , Berzins K. , López M. C. , Fernández C. 
Published: September 2003

AbstractPoor immunogenicity and major histocompatibility complex (MHC) restriction of immune responses to certain recombinant proteins or synthetic peptides impose problems in developing effective vaccines. EB200 is one of the vaccine candidate antigens from Plasmodium falciparum, which induces MHC‐restricted immune responses in mice of different haplotypes. A way of overcoming this problem is to conjugate the antigen to an immunogenic protein carrier and to use optimal adjuvant substances. We have investigated the carrier effect of glutathione‐S‐transferase (GST) in CBA and C57BL/6 mice which are high and low responder to EB200, respectively. Our results reveal that the MHC restriction in C57BL/6 mice was broken by the use of GST as a carrier. Studies on the B‐cell repertoires in both strains of mice immunized with GST‐EB200 by preparing hybridoma cell lines indicate that the B‐cell repertoires were similar in both CBA and C57BL/6 mice. However, the antibody affinity and the magnitude of the response were still lower in the low‐responder C57BL/6 mice compared with that in CBA even when cholera toxin (CT) was used as adjuvant. To improve the response, the efficacy of various adjuvant substances like alum and Hsp 70 from Trypanosoma cruzi and the combination of various adjuvants was analysed. CT and Hsp 70 together act synergistically and markedly improve the immunogenicity of EB200 by increasing antibody affinity and the magnitude of the responses in C57BL/6 mice, which may be explained by the complementary effect of adjuvants. These results are of importance in the design of efficient vaccines.
Immunobiological Effects of Glucosamine In Vitro
Authors: Forchhammer L. , Thorn M. , Met O. , Gad M. , Weidner M. S. , Claesson M. H. 
Published: September 2003

AbstractGlucosamine (GlcN) and N‐acetyl‐d‐glucosamine (GlcNAc) were assayed in vitro for their effects on proliferation, cytotoxicity and cytokine secretion in primary and secondary mixed lymphocyte cultures (MLCs). In addition, we studied the effect of GlcN and GlcNAc on the proliferation of purified CD4+ T cells exposed to immobilized anti‐CD3 antibody. The present data show that GlcN, but not GlcNAc, inhibits CD4+ T‐cell proliferation, the generation of alloreactive cytotoxic T lymphocytes (CTLs) and the secretion of interferon‐γ (IFN‐γ) and interleukin‐5 (IL‐5) in primary MLC. In secondary T helper‐2 (Th2)‐polarized MLC, GlcN, but not GlcNAc, inhibits IL‐4 and IL‐5 secretion, whereas no effect was found on IFN‐γ secretion in Th1‐polarized MLC. Dendritic cells treated with GlcN showed a 75–80% decreased capacity for antigen cross‐presentation and allostimulation. In cellular bioassays, GlcN was shown to inhibit the stimulatory activity of IL‐4 and IL‐2, as well as the cytotoxic activity of tumour necrosis factor‐α (TNF‐α). In conclusion, GlcN suppresses unprimed T‐cell responses by interfering with antigen‐presenting cell functions and by a direct inhibitory effect on T‐cell proliferation. In addition, GlcN inhibits the secretion of cytokines in antigen‐stimulated unprimed T cells and primed Th2‐polarized cells.
Enhanced Adhesion to Laminin by Apoptotic Eosinophils
Authors: Seton K. , Håkansson L. , Venge P. 
Published: September 2003

AbstractApoptotic cells are regarded as inert bodies that turn off intracellular processes and functional capabilities. The objective was to study adhesion by eosinophils in relation to the apoptotic process. Eosinophils were cultured for up to 72 h. The living cells were separated from the apoptotic cells, and their adhesion to transfected cell lines expressing vascular cell adhesion molecule‐1 (VCAM‐1), intercellular adhesion molecule‐1 (ICAM‐1), E‐selectin and laminin was measured. To relate the functional studies with cell structure, the surface receptor expression of β1‐ and β2‐integrins was investigated by flow cytometry. Apoptotic eosinophils evidenced an increased expression of the α‐chain of the laminin receptor and CD49f and an increased ability to adhere to a laminin‐coated surface. Adhesion to the endothelial cell adhesion receptors E‐selectin, VCAM‐1 and ICAM‐1 was absent in apoptotic eosinophils and was paralleled by a low expression of CD11b, CD29, CD49d and CD66b. The specifically increased adhesion to laminin and expression of the laminin receptor α‐chain is a unique feature of apoptotic eosinophils. When an eosinophil goes into apoptosis, it still possesses the ability to interact with its environment. Our results point to new ideas as to how the apoptotic eosinophil behaves in apoptosis.
Mycobacterium tuberculosis Virulence Correlates with Mitochondrial Cytochrome c Release in Infected Macrophages
Authors: Abarca‐Rojano E. , Rosas‐Medina P. , Zamudio‐Cortéz P. , Mondragón‐Flores R. , Sánchez‐García F. J. 
Published: September 2003

AbstractMitochondria are at the centre of molecular events involved in energy production, cell survival and apoptosis. Mitochondrial membrane potential (Δψm) is maintained by cellular catabolic reactions and the electron transport chain of which cytochrome c is a constituent, whereas the proton leak pathway, ATP synthesis and turnover consume it. Mitochondrial alterations such as a drop in Δψm, swelling and cytochrome c release have been observed in apoptosis. However, there is a paucity of information concerning mitochondrial function in the course of intracellular infections, a process that must certainly induce stress on the host cell. This work analyses the effect that two strains of mycobacteria of opposing virulence have on the mitochondria of murine macrophages in the early stages of infection. It was found that infection of J774 cells with both Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv readily induced changes in Δψm as well as in mitochondrial morphology at the ultrastructural level. In addition, an increase in cytosolic ATP was found at 24 h post infection with both strains of M. tuberculosis. Interestingly, only M. tuberculosis H37Rv was able to induce cytochrome c release from mitochondria to the cytosol, thus suggesting the occurrence in M. tuberculosis H37Rv of a specific factor(s) capable of regulating cytochrome c translocation. The precise role of cytochrome c release in the context of a mycobacterial infection remains to be elucidated.
Optimization of Functional Efficacy of Phosphorothioate‐Modified Oligonucleotides in a Human CD8+ T‐Cell Ex Vivo Expansion Model
Authors: Al‐Shanti N. A. , Steward C. G. , Garland R. J. 
Published: September 2003

AbstractAntisense oligodeoxyribonucleotides (ODNs) can specifically inhibit gene expression, but their application to fresh human CD8+ T cells is limited by poor spontaneous uptake (<2%). We have examined and optimized the uptake of phosphorothioate‐modified oligodeoxyribonucleotides (PS‐ODNs) into these cells in an ex vivo expansion model. Optimal antisense treatments were found to be, for fresh CD8+ T cells, 1 µm PS‐ODNs complexed with lipofectin (LF), which resulted in 35% uptake and 10 µm PS‐ODNs in the absence of LF, for cultured cells, which resulted in 95% uptake. The delivered antisenses were functional, as determined by the inhibition of protein expression. In this respect, partially phosphorothioate‐modified ODNs (PS‐ODNs‐P) were twice as effective as completely modified (PS‐ODNs‐C), and the antisense specific for the cap site showed the highest protein suppression of those tested (68%). Uptake mechanisms were also investigated. To our knowledge, this is the first optimization of the delivery of antisense oligonucleotides into human CD8+ T cells. This protocol could be used to study the function of a particular gene in cytotoxic T lymphocytes and also by those looking for a method to deliver short interfering RNA into cell lines to specifically suppress a gene of interest.
Delta‐F508 cystic fibrosis mutation is not linked to intussusception: Implications for rotavirus vaccine
Authors: Barnes G , Srivastava A , Carlin J , Francis I 
Published: September 2003

Objective: To determine whether the cystic fibrosis (CF) delta‐F508 gene mutation predisposes to intussusception, and so selects infants who should not receive rotavirus vaccine.Methods:  Stored neonatal screening blood spots, retrieved from 81 infants with intussusception and from 79 controls, were tested for the presence of the CF delta‐F508 gene mutation.Results:  Prevalence of the mutation was similar in blood specimens from intussusception patients and from controls. Conclusion: Testing for the CF delta‐F508 mutation at birth is unlikely to identify infants predisposed to intussusception, and therefore is not relevant to rotavirus vaccine programs.
Respiratory health in Aboriginal and Torres Strait Islander children in the Australian Capital Territory
Authors: Glasgow NJ , Goodchild EA , Yates R , Ponsonby A‐L 
Published: September 2003

Objectives:  To measure the prevalence of respiratory symptoms and atopic disease in Aboriginal and Torres Strait Islander (indigenous) and non‐indigenous children in the Australian Capital Territory (ACT).Methods:  A two‐stage questionnaire survey of children in the ACT with stage two completed for children identified by parents as having respiratory symptoms or asthma in the first stage cross‐sectional survey. Participants in the study were: (i) all new entrant primary schoolchildren aged 4−6 years in 1999, 2000 and 2001, 217 being indigenous children and 10 604 being non‐indigenous children (80% of eligible); and (ii) Year 1−6 primary schoolchildren in 2000, with 216 being indigenous children and 14 202 being non‐indigenous children (52% of eligible). Respiratory symptoms (including recent wheeze and parent‐reported asthma) and other factors were measured by parental questionnaire.Results:  Indigenous kindergarten children had more recent wheeze (21%, odds ratio (OR) 1.4 95% confidence interval (CI) 1.0−2.0)) and parent‐reported asthma (24%, OR 1.8 95% CI 1.3−2.5) than non‐indigenous children (both 15%). However, indigenous children had less eczema (25%, OR 0.7 95% CI 0.5−0.9) and hayfever (14%, OR 0.7 95% CI 0.5−1.0) than non‐indigenous children (32% and 19%, respectively). Among children with respiratory symptoms, the symptom severity did not differ between groups, but indigenous children were exposed to more environmental tobacco smoke (ETS) (63%, OR 3.5 95% CI 2.1−5.9) than non‐indigenous children (32%).Conclusions:  Indigenous children in the ACT have more respiratory morbidity but less of the atopic diseases of hayfever and eczema than non‐indigenous children. Whether the respiratory morbidity represents ‘asthma’ or results from increased ETS exposure is unclear and needs to be further explored.
Vitamin D status of chronically ill or disabled children in Victoria
Authors: Greenway A , Zacharin M 
Published: September 2003

Objective:  To establish the percentage prevalence of hypovitaminosis D in chronically ill or disabled children in Melbourne, Australia.Methodology:  A group of inpatients at the Royal Children's Hospital, Melbourne, Victoria, as identified by the primary unit, were sampled to measure serum vitamin D and parameters of bone turnover. A second group of disabled children (outpatients) were also measured to establish vitamin D status.Results:  Of the total population, 54.9% were found to have low serum 25 hydroxy (25OH) vitamin D levels. Of the inpatient group, 25.4% were vitamin D deficient (<30 nmol/L), and 27.1% were vitamin D insufficient (30−50 nmol/L). The mean 25OH vitamin D was 52.1 nmol/L. Of the outpatient group, 15.4% were vitamin D deficient, whilst 42.3% were found to be insufficient. The mean vitamin D level was 41.2 nmol/L. No difference attributable to intellectual versus physical disability was found. Anticonvulsant use and ambulatory status was not predictive of vitamin D status in the children examined. Of the total population, 0.05% were found to have secondary hyperparathyroidism. The mean 25OH vitamin D level of this subgroup was 30.6 nmol/L. Dark skin tone was found to be significantly associated with hypovitaminosis D (P = 0.001), where all five children with dark skin tone were found to have serum 25OH vitamin D levels <50 nmol/L. Of the seven disabled children (outpatients) found to be iron deficient, four had coexistent hypovitaminosis D.Conclusion:  The percentage prevalence of hypovitaminosis D is high in both chronically ill, and physically/intellectually disabled children in Melbourne, Australia. Increased vigilance and recognition of this deficiency state is needed as an important health prevention strategy.
Infestation by cabbage aphid (Brevicoryne brassicae) on oilseed rape (Brassica napus) causes a long lasting induction of the myrosinase system
Authors: Pontoppidan Bo , Hopkins Richard , Rask Lars , Meijer Johan 
Published: September 2003

AbstractCabbage aphid, Brevicoryne brassicae (L.) (Hemiptera: Aphididae), is specialised on cruciferous plants and constitutes a world‐wide problem with a substantial negative impact on agriculture and horticulture. The myrosinase‐glucosinolate system present in crucifers is believed to serve as an important barrier to general herbivores, whereas specialist insects rely on this system for host recognition. Two proteins with unknown function, myrosinase binding protein (MBP) and myrosinase associated protein (MyAP), are also present in such plants and bind to specific myrosinases. In order to study regulation and overall effects on the myrosinase system, one leaf of oilseed rape (Brassica napus L.) (Brassicaceae) plants at the two‐leaf stage was exposed to cabbage aphids for 1 h. After removal of the insects, infested and non‐infested leaves were analysed by Northern blot analysis for the presence of MBP, MyAP, and myrosinase transcripts at different time points up to 48 h. MBP transcript levels continued to rise during the whole experiment, and were seven‐ to eight‐fold higher compared with control plants 48 h after removal of the aphids. At 24 h the MyAP transcripts reached maximal levels and were four‐fold higher than the control levels. Myrosinase transcripts were down regulated by aphid infestation and the level was less than half that of the control plants at 48 h. Apparently cabbage aphid infestation causes both transient and more long lasting (up to 48 h) effects on the myrosinase system of the host.
Characteristics associated with Woolly Apple Aphid Eriosoma lanigerum, resistance of three apple rootstocks
Authors: Sandanayaka W.R.M. , Bus V.G.M. , Connolly P. , Newcomb R. 
Published: September 2003

AbstractThe resistance characteristics of the apple resistance genes (Er1, Er2, and Er3) to the woolly apple aphid, Eriosoma lanigerum (Hausmann) (Homoptera: Aphididae) were studied according to the performance measured on apple cultivars containing these resistance genes. The resistance characteristics of Northern Spy (Er1), Robusta 5 (Er2), and Aotea (Er3) were compared to the susceptible cultivar Royal Gala, by measuring the aphid settlement, development, and survival rates correlated with electronically monitored probing behaviour. Er1 and Er2 had a higher level of resistance with a significantly shorter period of phloem feeding, suggesting that the resistance factors were present in the phloem tissue. Phenological measurements indicated that the aphids showed poor settlement, development, and survival on Er2. Er1 also showed low settlement and survival, although not as low as Er2. Aphid performance and feeding on Aotea (Er3) were similar to Royal Gala, suggesting that some woolly apple aphids in New Zealand may have recently overcome Er3 resistance. The differences in resistance mechanisms of Er1, Er2, and Er3 are discussed in relation to the strategy of pyramiding these genes to give a durable resistance to woolly apple aphid.
Special Economic Zones in Developing and/or Transition Economies: a Policy Proposal
Authors: Schweinberger Albert G. 
Published: September 2003

AbstractMaking use of a global partitioning (disintegration) approach, a novel necessary and sufficient condition for the creation of Pareto‐improving special economic zones is derived. It is shown that the establishment of a special economic zone may be desirable even if foreign investment has an immiserization effect. The present approach allows not only for the use of mobile but also immobile domestically owned factors in the special economic zone. Adopting a political economy perspective, multihousehold economies with and without the feasibility of lump‐sum compensation are modeled. It is shown that, subject to a certain condition, the setting up of special economic zones accompanied by appropriate tax policies results in an increase in government revenue. The latter may be used to finance much‐needed investment in infrastructure or the production of public goods.
The Lens Condition with Two Factors
Authors: Wong Siu‐kee , Yun Kwan Koo 
Published: September 2003

AbstractThe authors give a simple, constructive proof that the lens condition implies the factor price equalization condition when there are only two factors. Taking stock of the conditions under which the lens condition is equivalent to the factor price equalization condition, there are the conditions of two factors or two goods or two countries, or the condition that the rank of the factor‐use matrix is equal to the number of goods. It is shown that, in an essential sense, there are no other such conditions.
Developing‐Country Benefits from MFN Relative to Regional/Bilateral Trade Arrangements
Authors: Ghosh Madanmohan , Perroni Carlo , Whalley John 
Published: September 2003

AbstractUsing a general‐equilibrium model of world trade, this paper evaluates the benefits of most‐favored‐nation (MFN) treatment to developing countries in multilateral relative to bilateral or regional trade agreements, from three sources. First, developing countries may be able to free‐ride on bilateral tariff concessions exchanged between larger countries in MFN‐based GATT/WTO rounds. Second, MFN benefits developing countries by restricting discriminatory retaliatory actions by other countries, evaluated here by a non‐ cooperative Nash tariff game. Finally, MFN changes threat points in bargaining and hence affects the bargaining solution of multilateral MFN‐based trade negotiation compared to a bilateral/regional arrangement. The authors find that the benefits to developing countries are small in the first case as the tariff rates are already low, and the benefits are small in the second case as the optimal tariffs under unconstrained retaliation are not very asymmetric. Benefits from the third case are large as large countries can extract large side‐payments if they bargain bilaterally.
RelA Is a Component of the Nutritional Stress Activation Pathway of theBacillus subtilisTranscription Factor σB
Authors: Zhang Shuyu , Haldenwang W. G. 
Published: September 2003

ABSTRACTThe general stress regulon ofBacillus subtilisis induced by the activation of the σBtranscription factor. Activation of σBoccurs when one of two phosphatases (RsbU and RsbP), each responding to a unique type of stress, actuates a positive regulator of σBby dephosphorylation. Nutritional stress triggers the RsbP phosphatase. The mechanism by which RsbP becomes active is unknown; however, its activation coincides with culture conditions that are likely to reduce the cell's levels of high-energy nucleotides. We now present evidence that RelA, a (p)ppGpp synthetase and the key enzyme of the stringent response, plays a role in nutritional stress activation of σB. An insertion mutation that disruptsrelAblocks the activation of σBin response to PO4or glucose limitation and inhibits the drop in ATP/GTP levels that normally accompanies σBinduction under these conditions. In contrast, the activation of σBby physical stress (e.g., ethanol treatment) is not affected by the loss of RelA. RelA's role in σBactivation appears to be distinct from its participation in the stringent response. Amino acid analogs which induce the stringent response and RelA-dependent (p)ppGpp synthesis do not trigger σBactivity. In addition, neither a missense mutation inrelA(relA240GE) nor a null mutation inrplK(rplK54), either of which is sufficient to inhibit the stringent response and RelA-dependent (p)ppGpp synthesis, fails to block σBactivation by PO4or glucose limitation.