bluuebunny/crossref_metadata_2025 huggingface dataset:
The prevalence of, and molecular defects underlying, inherited protein S deficiency in the general population
Authors: Beauchamp Nicholas J. , Dykes Anne C. , Parikh Nirzari , Campbell Tait R. , Daly Martina E.
Published: May 2004

The molecular basis of protein S (PS) deficiency was investigated in seven of eight donors identified with persistently low plasma PS levels from a survey of PS levels in 3788 Scottish blood donors. PROS1 gene analysis identified at least one defect in six donors. Five were heterozygous for the Heerlen polymorphism predicting a Ser460Pro substitution. Haplotype analysis revealed the possibility that this allele was inherited with the same haplotype in four of the five donors, suggesting a founder effect for the Heerlen allele in this population. One Heerlen allele carrier was also heterozygous for a 3 bp deletion 68–72 bp upstream of exon 2. Platelet PROS1 transcript analysis showed no reduction in mRNA expression from the affected allele in this donor. A T to G transversion 3 bp upstream of exon 12 was identified in one donor, which is predicted to reduce the efficiency of PS mRNA splicing. However, PROS1 transcript analysis showed no evidence of exon skipping or cryptic splicing. No PROS1 gene defect was detected in the remaining donor. This genetic information enabled us to refine our estimate of the prevalence of heritable PS deficiency in the Scottish population to between 0·16% and 0·21%, predominantly resulting from the presence of the Heerlen allele.
ChlVPP/ABVVP, a first line ‘hybrid’ combination chemotherapy for advanced Hodgkin's lymphoma: a retrospective analysis
Authors: Martinelli G. , Cocorocchio E. , Peccatori F. , Zucca E. , Saletti P. C. , Calabrese L. , Pastano R. , Pruneri G. , Mazzetta C. , Ghielmini M. , Cavalli F.
Published: May 2004

We retrospectively analysed toxicities and clinical results of 61 Hodgkin's lymphoma patients treated with chlorambucil, vinblastine, procarbazine, doxorubicin, bleomycin, vincristine and etoposide (ChlVPP/ABVVP), delivered in a weekly alternate schedule. Of 61 patients, 33 were in stages III–IV, 21 in stage IIB and seven in stage IIA with bulky disease or extranodal presentation. ChlVPP/ABVVP was administered for 6–8 cycles. Involved field radiotherapy (IFRT) (30–35 Gy) was delivered to 31 patients with residual disease after chemotherapy or bulky disease at diagnosis. Of 61 patients, 58 (95%) achieved complete clinical or radiological remission after chemotherapy and IFRT. With a median follow‐up of 60 months, 5‐year overall survival, relapse‐ and event‐free survival were 78·8% (95% CI 68·2–91·1%), 81% (95% CI 70·6–92·2%) and 71·9% (95% CI 68·2–82·2%) respectively. Grades 3–4 neutropenia was the most relevant haematological toxicity and occurred in 82% of patients. Non‐haematological toxicities were mild and reversible. No toxic deaths were recorded. One patient developed secondary acute myeloid leukaemia 1 year after ChlVPP/ABVVP. Due to the retrospective nature of this study, no definitive conclusions could be drawn about the clinical activity of ChlVPP/ABVVP. Nonetheless, clinical results seem better than those reported with standard regimens [ABVD (doxorubicin, bleomycin, vincristine, dacarbazine), MOPP (methotrexate, vincristine, procarbazine, prednisone), MOPP/ABVD] and as good as those reported using standard or escalated BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine and prednisone), with a lower degree of haematological and non‐haematological toxicity. Long‐term results of the ongoing randomized trial, comparing ABVD versus high‐dose intensity weekly regimens will be useful to confirm our results.
Role of Toll‐like receptor 4 in the initiation and progression of atherosclerotic disease
Authors: Pasterkamp G. , Van Keulen J. K. , De Kleijn D. P. V.
Published: May 2004

The family of Toll‐like receptors (TLRs) initiates an innate immune response after recognition of pathogen‐associated molecular patterns (PAMPs). Evidence is accumulating that TLRs, and particularly TLR4, are important players in the initiation and progression of atherosclerotic disease. Not only exogenous ligands but also endogenous ligands that are expressed during arterial injury are recognized by TLR4. Mouse knockout studies and epidemiological studies of human TLR4 polymorphisms have demonstrated that the TLR4 might play a role in the initiation and progression of atherosclerosis. This review will summarize the latest progression in research on the role of TLR4 in arterial occlusive disease In addition, the potential of intervention in TLR4 signalling to influence progression of atherosclerotic disease is discussed.
Reactive oxygen species induce RNA damage in human atherosclerosis
Authors: Martinet W. , De Meyer G. R. Y. , Herman A. G. , Kockx M. M.
Published: May 2004

Background  Reactive oxygen species (ROS)‐induced DNA damage has recently been identified in both human and experimental atherosclerosis. This study was undertaken to investigate whether RNA damage occurs in human atherosclerotic plaques and whether this could be related to oxidative stress.

Materials and methods  The integrity of total RNA isolated from carotid endarterectomy specimens (n = 20) and nonatherosclerotic mammary arteries (n = 20) was analyzed using an Agilent 2100 Bioanalyser (Agilent Technologies, Palo Alto, CA). Oxidative modifications of RNA were detected by immunohistochemistry.

Results  Eleven out of 20 atherosclerotic plaques showed a significant reduction of the 18S/28S rRNA peaks and a shift in the RNA electropherogram to shorter fragment sizes. In contrast, all mammary arteries showed good‐quality RNA with clear 18S and 28S rRNA peaks. Strong nuclear and cytoplasmic immunoreactivity for oxidative damage marker 7,8‐dihydro‐8‐oxo‐2′‐guanosine (8‐oxoG) could be detected in the entire plaque in smooth muscle cells (SMCs), macrophages and endothelial cells, but not in SMCs of adjacent normal media or in mammary arteries. Cytoplasmic 8‐oxoG staining in the plaque clearly diminished when tissue sections were pretreated with RNase A, suggesting oxidative base damage of RNA. In vitro treatment of total RNA with ROS‐releasing compounds induced RNA degradation.

Conclusion  Both loss of RNA integrity and 8‐oxoG oxidative modifications were found in human atherosclerotic plaques. Because RNA damage may affect in vitro transcript quantification, RT‐PCR results must be interpreted cautiously if independent experimental validation (e.g. evaluation of RNA integrity) is lacking.
Basal and exercise‐induced sympathetic nervous activity and lipolysis in adipose tissue of patients with anorexia nervosa
Authors: Bartak V. , Vybiral S. , Papezova H. , Dostalova I. , Pacak K. , Nedvidkova J.
Published: May 2004

Background  The sympathetic nervous system plays an important role in the regulation of adipose tissue (AT) lipolysis, which is a key step in the metabolic processes leading to the decrease of fat mass. The present study was designed to determine in vivo basal and exercise‐stimulated lipolysis and concentrations of catecholamines, the major hormones controlling lipolysis, in subcutaneous abdominal AT in patients with anorexia nervosa (AN), characterized by self‐induced starvation and excessive exercises resulting in severe malnutrition and fat store loss. The results of local catecholamines and glycerol levels were compared with those in plasma in both experimental groups.

Material and methods  An in vivo microdialysis technique was used for the assessment of norepinephrine, dihydroxyphenylalanine, dihydroxyphenylacetic acid and glycerol concentrations in subcutaneous AT of 10 women with AN (body mass index: 15·57 ± 0·55 kg m−2) and 10 age‐matched controls (body mass index: 21·56 ± 0·41 kg m−2). Both the AN patients and the control subjects underwent a 1·5 W kg−1 exercise test.

Results  Basal AT norepinephrine concentrations were increased in the AN patients in comparison with the controls. Basal AT glycerol concentrations were similar in both groups. During exercise, a local increase in the AT norepinephrine and glycerol concentrations was observed in the AN patients only. In contrast to the controls, the basal AT dihydroxyphenylalanine and dihydroxyphenylacetic acid levels in the AN patients were high and remained unchanged during exercise. Basal and exercise‐stimulated plasma norepinephrine, dihydroxyphenylalanine, dihydroxyphenylacetic acid and glycerol levels were not different in the AN patients and healthy controls.

Conclusion  Our study provides evidence of elevated baseline and exercise‐induced sympathetic nervous activity and exercise‐induced lipolysis in abdominal AT of AN patients.
Low‐grade systemic inflammation impairs arterial stiffness in newly diagnosed hypercholesterolaemia
Authors: Pirro M. , Schillaci G. , Savarese G. , Gemelli F. , Vaudo G. , Siepi D. , Bagaglia F. , Mannarino E.
Published: May 2004

Background  Excess of cardiovascular risk among patients with chronic inflammatory diseases has been attributed to increased arterial stiffness. Hypercholesterolaemia has been demonstrated to promote a low‐grade inflammatory status. The objective of the present study was to define, in hypercholesterolaemia, the influence of plasma lipids, low‐grade inflammation, and indices of adiposity on aortic pulse wave velocity, a measure of arterial stiffness and cardiovascular risk.

Materials and methods  Anthropometric characteristics, plasma lipids, C‐reactive protein and aortic pulse wave velocity were measured in 85 subjects (60 patients with newly diagnosed never‐treated hypercholesterolaemia and 25 age‐ and sex‐matched normocholesterolaemic controls).

Results  Plasma C‐reactive protein and aortic pulse wave velocity were significantly higher among hypercholesterolaemic patients than in controls (P < 0·05 for both). Aortic pulse wave velocity was associated with age (r = 0·24, P = 0·04), body mass index (r = 0·33, P = 0·006), waist (r = 0·42, P < 0·001) and hip (r = 0·32, P = 0·007) circumferences, as well as with systolic (r = 0·34, P = 0·003) and diastolic (r = 0·30, P = 0·01) blood pressures, plasma C‐reactive protein (r = 0·51, P < 0·001), total cholesterol (r = 0·45, P < 0·001), and low‐density lipoprotein cholesterol (r = 0·46, P < 0·001). In the multivariate analysis, waist circumference and C‐reactive protein levels predicted increased aortic stiffness, independently of traditional cardiovascular risk factors. The degree of independent association between cholesterol, systolic blood pressure and aortic stiffness increased when indices of adiposity and inflammation were excluded from the multivariate analysis. Comparable results were obtained when the analyses were restricted to hypercholesterolaemic patients.

Conclusions  Low‐grade systemic inflammation and abdominal fat, more than traditional risk factors, are major determinants of reduced arterial distensibility in hypercholesterolaemia.
Increasing neutrophil F‐actin corrects CD11b exposure in Type 2 diabetes
Authors: Advani A. , Marshall S. M. , Thomas T. H.
Published: May 2004

Background  Leukocyte dysfunction contributes to the pathogenesis of diabetic vascular complications. Neutrophils adhere to the endothelium through the β2integrin CD11b/CD18. In Type 2 diabetes, neutrophil surface CD11b expression is increased and is associated with impaired actin polymerization. This study aimed to determine whether increasing neutrophil actin polymerization could correct the defect in CD11b exposure.

Design  Neutrophil actin polymerization was stimulated with the tyrosine phosphatase inhibitor phenylarsine oxide (PAO), and cytoskeletal phosphotyrosine was monitored by immunoblotting Triton X‐100 insoluble fractions of cells. Neutrophil F‐actin was measured with phalloidin‐FITC staining, and surface CD11b expression was determined with anti‐CD11b‐PE before analysis with flow cytometry.

Results  Phenylarsine oxide caused an increase in phosphotyrosine in neutrophils from both patients with Type 2 diabetes (DM) and controls (NC) (‐fold increase: NC, 1·43 ± 0·16; DM, 1·46 ± 0·10). The response to PAO in terms of phalloidin‐binding was impaired in neutrophils from patients [phalloidin‐FITC MFI area under the curve, NC 200 ± 5 (× 103), DM 124 ± 9 (× 103), P < 0·0001]. Phenylarsine oxide at concentrations < 10 µmol L−1 also caused loss of CD11b from neutrophil surfaces that was impaired in samples from patients [CD11b sites area under the curve NC 90 ± 6 (× 103), DM 121 ± 9 (× 103), P < 0·002]. However, in neutrophils from patients, incubation with PAO at a concentration of > 10 µmol L−1 caused a significant increase in intracellular F‐actin and CD11b down‐regulation equivalent to that observed in controls.

Conclusion  In Type 2 diabetes, impaired neutrophil actin polymerization even in response to increasing cytoskeletal phophotyrosine suggests a downstream defect. Furthermore, increasing actin polymerization, above a minimum threshold level, corrects the defect in integrin exposure. Correction of the actin polymerization defect in Type 2 diabetes could improve the prognosis of diabetic vascular complications.
Natriuretic peptides as markers of preclinical cardiac disease in obesity
Authors: Grandi A. M. , Laurita E. , Selva E. , Piantanida E. , Imperiale D. , Giovanella L. , Guasti L. , Venco A.
Published: May 2004

Background  Aim of the study was to evaluate the role of atrial (ANP) and brain natriuretic peptides (BNP) as markers of preclinical cardiac disease in obesity.

Methods  We selected 26 obese (BMI > 29 kg m−2) never‐treated hypertensives (24‐h BP > 140 and/or 90 mmHg), 26 obese normotensives (24‐h BP < 130/80 mmHg) and 25 lean (BMI  25 kg m−2) never‐treated hypertensives. Each subject underwent measurements of ANP and BNP plasma levels, 24‐h ambulatory blood pressure (BP) monitoring, digitized M‐mode and Doppler echocardiography.

Results  Mean values of ANP and BNP were similar among the three groups. All the subjects had normal left ventricular (LV) systolic function. Within each group ANP levels were higher in patients with LV diastolic dysfunction than in patients with normal diastolic function, and BNP levels were higher in patients with LV hypertrophy and in patients with LV diastolic dysfunction. Within each group, ANP levels were inversely correlated with LV diastolic indices, whereas BNP levels were directly correlated with LV mass index and inversely correlated with LV diastolic indices. ANP and BNP levels were not correlated with other echocardiographic parameters, age, BMI or 24‐h BP values.

Conclusion  In normotensive and hypertensive obese subjects the relationships of ANP and BNP levels with LV morpho‐functional characteristics follow the same trend as in lean hypertensives, with ANP mainly influenced by diastolic dysfunction and BNP influenced by both LV hypertrophy and LV diastolic dysfunction. Therefore ANP and BNP can be considered useful markers of preclinical cardiac disease in obesity.
Radioiodine therapy in hyperthyroidism: inverse correlation of pretherapeutic iodine uptake level and post‐therapeutic outcome
Authors: Walter M. A. , Christ‐Crain M. , Eckard B. , Schindler C. , Nitzsche E. U. , Müller‐Brand J. , Müller B.
Published: May 2004

Background  High iodine uptake levels are widely accepted as a condition for successful treatment with radioiodine (RAI). However, the existing data are controversial and the correlation of pretherapeutic RAI uptake level and outcome of RAI therapy has not yet been quantified. The aim of this study was to analyze the influence of RAI uptake on the outcome after RAI treatment and to estimate uptake‐dependent success rates.

Materials and methods  We retrospectively analyzed 229 patients (m = 53, f = 176; age 64 ± 14 years) suffering from toxic adenoma, multinodular goitre or Graves’ disease, respectively. Clinical status and T3, fT4 and TSH levels were assessed 3, 6, 12 and 18 months after treatment. Successful treatment was defined as loss of hyperthyroidism 18 months after radioiodine therapy. Logistic regression was used to assess the relation between the maximum iodine uptake and the rate of success and hypothyroidism, respectively, after RAI treatment.

Results  Overall, patients presented with pretherapeutic RAI uptake values between 17% and 100%. Eighteen months after RAI treatment, an euthyroid state was achieved in 136 patients (60%), hypothyroidism occurred in 47 patients (20%) and 46 patients (20%) remained hyperthyroid. The patients with the lowest pretherapeutic RAI uptakes showed the highest success rates. The overall success rate significantly decreased from 92% at low RAI uptakes to 57% at high uptakes (P = 0·002). This effect was found in the patients suffering from multinodular goitre as well as in the patients with Graves’ disease.

Conclusion  In contrast to the current opinion, our results provide evidence that the pretherapeutic iodine uptake level and post‐therapeutic outcome are inversely correlated.
Seasonal changes in the stable isotope values of lake‐dwelling chironomid larvae in relation to feeding and life cycle variability
Authors: Grey Jonathan , Kelly Andrew , Ward Susan , Sommerwerk Nike , Jones Roger I.
Published: May 2004

1. We studied seasonal changes in the carbon and nitrogen stable isotope ratios of larval Chironomus anthracinus and C. plumosus from the profundal sediments of four contrasting lakes.

2. Pronounced seasonal changes in both δ13C and δ15N values were evident in chironomid larvae of both species from two summer‐stratified, eutrophic lakes: Esthwaite Water and Wyresdale Park. Changes were most marked in the larvae of C. plumosus and in larvae from greater depths. In contrast, neither C. anthracinus in summer‐stratified but mesotrophic Schöhsee, nor C. plumosus in polymictic Großer Binnensee, showed marked seasonality in larval stable isotope ratios.

3. The particularly strong 13C‐depletion of larvae from the stratified, eutrophic lakes is attributed to a significant contribution of methane‐derived carbon to their diets. Feeding by larvae on isotopically light methanotrophic bacteria appears to occur mainly when autumn overturn of the water column restores oxygenated conditions to the sediment surface. At this time both δ13C and δ15N values of larvae decreased sharply.

4. Changes in the mean stable isotope ratio of the larval populations can also occur when larger, more isotopically light, larvae pupate and emigrate from the population to hatch as imagos. This effect can induce seasonal changes in larval isotope values even in lakes in which there is no evidence of a significant involvement of methane‐derived carbon in their diets. Variations in emergence patterns between species and between lakes may generate differences in the seasonal pattern of change in stable isotope ratios in larval populations.

5. Our results emphasise the importance of adequate seasonal sampling if stable isotope ratios are to be used as biomarkers to study the role of key groups, such as chironomid larvae, in the trophic structure of lakes.
Do cyanobacteria dominate in eutrophic lakes because they fix atmospheric nitrogen?
Authors: Ferber L. R. , Levine S. N. , Lini A. , Livingston G. P.
Published: May 2004

1. The sources of nitrogen for phytoplankton were determined for a bloom‐prone lake as a means of assessing the hypothesis that cyanobacteria dominate in eutrophic lakes because of their ability to fix nitrogen when the nitrogen : phosphorous (N : P) supply ratio is low and nitrogen a limiting resource.

2. Nitrogen fixation rates, estimated through acetylene reduction with 15N calibration, were compared with 15N‐tracer estimates of ammonium and nitrate uptake monthly during the ice‐free season of 1999. In addition, the natural N stable isotope composition of phytoplankton, nitrate and ammonium were measured biweekly and the contribution of N2 to the phytoplankton signature estimated with a mixing model.

3. Although cyanobacteria made up 81–98% of phytoplankton biomass during summer and autumn, both assays suggested minimal N acquisition through fixation (<9% for the in‐situ incubations; <2% for stable isotope analysis). Phytoplankton acquired N primarily as ammonium (82–98%), and secondarily as nitrate (15–18% in spring and autumn, but <5% in summer). Heterocyst densities of <3 per 100 fixer cells confirmed low reliance on fixation.

4. The lake showed symptoms of both light and nitrogen limitation. Cyanobacteria may have dominated by monopolizing benthic sources of ammonium, or by forming surface scums that shaded other algae.
Small reductions in forest cover weaken terrestrial‐aquatic linkages in headwater streams
Authors: England L. E. , Rosemond A. D.
Published: May 2004

1. We assessed the impacts of deforestation on the energy base of headwater food webs in seven headwater streams in the Upper Chattahoochee basin, GA, U.S.A where percentage forest in catchments ranged from 82 to 96%. We measured terrestrial organic matter standing crop and determined consumer (crayfish and insectivorous fish) dependence on terrestrial versus aquatic energy sources via gut content and stable isotope analyses.

2. Standing crop of coarse particulate organic matter (CPOM) declined with deforestation at large scales (i.e. catchment deforestation and riparian deforestation at the entire stream network scale). Terrestrial plant matter, the dominant component of crayfish guts, declined in crayfish guts with reductions in CPOM standing crop and with deforestation.

3. Crayfish and insectivorous fish δ13C showed enrichment trends with deforestation, indicating isotopic divergence from CPOM, the most 13C‐depleted basal resource, with reductions in catchment and riparian forest cover. Crayfish δ13C also exhibited enrichment with decreased instream CPOM standing crop.

4. A concentration‐dependent mixing model was used to calculate the relative dependence of crayfish and fish on terrestrial versus aquatic basal resources. Results suggested that both allochthonous CPOM and autochthonous production were important basal resources. Consumer dependence on CPOM decreased with reductions in canopy cover.

5. Our data suggest the importance of forest cover to headwater food webs at multiple scales, and that relatively low levels of riparian deforestation along headwater streams can lead to reductions in stream food web dependence on terrestrial subsidies.
Movement of plankton through lake‐stream systems
Authors: Walks D. J. , Cyr H.
Published: May 2004

1. River plankton are often assumed to come from upstream lakes, but the factors controlling the movement of plankton between lakes and rivers into outflow streams are unclear. We tested the possibility that the physical structure of the littoral zone near the lake outlet (depth, presence of macrophytes) and diurnal differences in plankton composition at the lake surface influence the movement of plankton from the lake into the stream and determine their persistence downstream.

2. Zooplankton and phytoplankton biomass, community composition and mean body size were compared between two deep lakes without macrophytes at the lake edge and two shallow lakes with macrophytes at the lake edge. Samples were collected day and night on three dates, in the lake centre, in the littoral zone adjacent to the lake outlet, at the outlet and at two sites downstream in Algonquin Park, Ontario, Canada.

3. The morphology of lake edges clearly affects the movement of lake zooplankton into outlet streams. Outlets draining deeper littoral zones had higher zooplankton biomass than shallow littoral outlets (P < 0.0001), but these differences disappeared within 50 m downstream of the lake. There was no difference in mean zooplankton body size among lake outlets or between littoral and outlet samples. However, shallow littoral zones were dominated by cyclopoid copepods and deeper littoral zones were dominated by Bosmina longirostris. In contrast, phytoplankton biomass entering the outlet was similar to that found within the lake and did not vary with lake outlet morphology. These effects were consistent across several sampling weeks and were not affected by surface zooplankton biomass changes associated with diurnal vertical migration in the lake centre.

4. A comparison with published river zooplankton data suggests that zooplankton are rapidly eliminated from shallow outlet streams (≤1 m deep) but persist in most deeper outlet rivers (≥2 m deep). Because the depth of an outlet river determines downstream zooplankton community development, the contribution of lakes to river plankton communities may be influenced by the location of each lake within the drainage basin. These findings suggest that lake and outflow physical structure influences connection strength between spatially successive habitats.
Bacterioplankton production in freshwater Antarctic lakes
Authors: Laybourn‐Parry Johanna , Henshaw Tracey , Jones Davey J. , Quayle Wendy
Published: May 2004

1. Bacterioplankton production was measured in the water columns of two ultra‐oligotrophic, freshwater Antarctic lakes (Crooked Lake and Lake Druzhby) during an annual cycle. In both lakes bacterial production, measured by the incorporation of [3H] thymidine, continued in winter and showed a cycle over the year. The range of production was between 0 and 479 ng C L−1 h−1 in Crooked Lake and 0–354 ng L−1 h−1 in Lake Druzhby.

2. Abundance and mean cell volume both varied, producing marked changes in biomass during the year, with highest biomass occurring in the winter and early spring. Biomass showed similar seasonal trends in both lakes.

3. For most of the year inorganic forms of nitrogen and phosphorus were detectable in the water columns of the lakes and were unlikely to have limited bacterial production. Dissolved organic carbon (DOC) was below 3000 μg L−1. Dissolved amino acids and carbohydrates contributed 5–25% of the DOC pool in Crooked Lake and 5–64% in Lake Druzhby. Dissolved carbohydrates were consistently low, suggesting that this may have been the preferred carbon substrate for bacterioplankton.

4. Aggregate associated bacteria had higher mean cell volume, abundances and production than freely suspended bacteria in Lake Druzhby, while in Crooked Lake aggregate associated bacteria consistently had higher mean cell volumes than free bacteria, but abundance and production were on occasion higher in free bacteria compared with aggregate associated communities.

5. The data indicated that production is limited by continuous low temperatures and the limited availability of suitable DOC substrate. However, the bacterioplankton functions year round, responding to factors other than temperature.
Prey switching in four species of carnivorous stoneflies
Authors: Elliott J. M.
Published: May 2004

1. Previous studies compared the functional responses to their prey, and both intraspecific and interspecific interference, in mature larvae ofDinocras cephalotes,Perla bipunctata,Isoperla grammaticaandPerlodes microcephalus. The present study examines switching by larvae of the same species presented with different proportions of two contrasting prey types; larvae ofBaetis rhodaniandChironomussp. In each experiment, 200 prey were arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40, 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency for switching could be tested.

2. No evidence for prey switching byDinocrasandPerlawas obtained, both species showing a slight preference forBaetisoverChironomus. Prey switching occurred inIsoperlaandPerlodes. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S‐shaped curve.IsoperlaandPerlodesswitched to a preference forBaetiswhen its percentage of the total available prey exceeded 57 and 42%, respectively. Equivalent values forChironomuswere 43 and 58% forIsoperlaandPerlodes, respectively. Switching was strongest inPerlodes.

3. Non‐switching inDinocrasandPerlawas related to their feeding strategy, both species being more successful when using a non‐selective ambush strategy at dusk and dawn rather than a search strategy during the night. BothIsoperlaandPerlodesused a search strategy. The smallerIsoperlafed chiefly at dusk and dawn, and preferredChironomuslarvae, whereas most of the largerPerlodesfed continuously from dusk to dawn and preferredBaetislarvae.
The influence of the North Atlantic Oscillation on the physical, chemical and biological characteristics of four lakes in the English Lake District
Authors: George D. G. , Maberly S. C. , Hewitt D. P.
Published: May 2004

1. Thirty‐six years of winter meteorological and limnological measurements from four lakes in the English Lake District are analysed and related to variations in the North Atlantic Oscillation (NAO). Winter weather conditions were strongly influenced by the NAO with mild, wet winters being associated with strongly positive values of the NAO index (NAOI).

2. Lake surface and bottom temperatures were strongly positively correlated with the NAOI, with the highest correlations being recorded in the shallower lakes.

3. Variations in the NAOI also had a significant effect on the winter concentration of nitrate. In all the lakes, there was a significant negative correlation between the NAOI and the detrended winter concentration of nitrate. The key driving variable was the local air temperature, which appeared to limit the quantity of nitrate reaching the lake by increasing the amount assimilated in the surrounding catchment in mild winters.

4. Dissolved reactive phosphorus (DRP) concentrations were not significantly correlated with the NAOI in the two larger basins but significant positive correlations were recorded in the two smaller lakes. The key driving variable was the local rainfall with higher DRP concentrations being recorded after heavy rain in the lakes with a short retention time.

5. The NAOI‐related changes in rainfall also influenced the phytoplankton. In wet winters the concentration of chlorophyll in the two smaller lakes with the shortest retention time was lower and the spring growth of Asterionella formosa was delayed in the smallest lake.

6. These differential responses demonstrate how the large‐scale effects associated with the NAO can be ‘filtered’ by the physical characteristics of a particular site.
Life history responses depend on timing of cannibalism in a damselfly
Authors: De Block M. , Stoks R.
Published: May 2004

1. Cannibalism has often been suggested as an important mechanism to reach the necessary developmental stage and size before a critical time horizon is reached, but this role has been largely unexplored. We studied effects of cannibalism on the life history of the damselflyLestes viridisunder combinations of a time constraint (by manipulating the perceived time available in the growth season) and a biotic constraint (density).

2. Larvae had a faster development and growth rate when reared at high time stress (late photoperiod). They also had a higher growth rate and mass at emergence when cannibalism occurred (density 2 and 4). Cannibalism occurred earlier at higher density. Accelerated life history responses (faster development and growth rate) and a higher mass at emergence were dependent upon the timing of cannibalism. Responses were more pronounced or only present if cannibalism occurred early in the larval period.

3. Our data suggest that cannibalism may not only act as a lifeboat mechanism by enabling cannibals to survive detrimental ecological conditions, but may also act as a compensatory mechanism to keep life history variables near‐optimal at life history transitions, even under sub‐optimal conditions.
Perturbation pathways affecting the avian lotic predator, blue duck, following a volcanic eruption
Authors: Collier Kevin J.
Published: May 2004

1. Perturbation pathways affecting interactions between feeding habitat, food supplies and diet of a lotic avian predator, blue duck (Hymenolaimus malacorhynchos Gemlin), were tracked in a New Zealand river following substantial inputs of sediment from a volcanic eruption. Sediment impacts were separated temporally into two distinct phases: (i) deposition of fine ash from volcanic fall‐out, and (ii) pulsed releases of volcanic sand and gravel retained by an upstream dam.

2. Levels of interstitial suspendable inorganic sediments increased by several orders of magnitude following ash inputs to the river, but returned to low levels within 3 months. Flushing of volcanic sand and gravel retained by the dam resulted in sediment deposition upstream of a large island where coarse material lodged firmly between larger benthic substratum elements in blue duck feeding habitat.

3. Changes in algal biomass appeared to largely reflect seasonal and hydrological influences, but the percentage inorganic content of periphyton increased significantly during both posteruption phases.

4. Diversity and abundance of blue duck food supplies on boulders and on the riverbed declined following the eruption, whereas significant impacts on biomass were only detected in benthic habitats which were more susceptible to sediment deposition. However, percent composition of the benthic and boulder invertebrate food resources appeared largely unaffected by the eruption.

5. There was no apparent association between the eruption and the composition or electivity (E*) of blue duck diet, but there was a significant increase in the percent inorganic content of faeces, suggesting a reduction in the quality of food rations.

6. Changes in food quantity and quality associated with deposition of volcanic sediments were linked to an observed decline in blue duck population density and fecundity following the eruption. An interacting continuum of adaptive responses to perturbation intensity and impact duration is proposed for blue duck, and potentially other long‐lived, riverine birds, that enable them to cope with disturbances in highly variable and heterogenous lotic environments.
The behaviour of an omnivorous protozoan affects the extent of induced morphological defence in a protozoan prey
Authors: Wia˛ckowski Krzysztof , Fyda Janusz , Ciećko Aneta
Published: May 2004

1. The ciliate Euplotes octocarinatus responds to the presence of Stylonychia mytilus with a morphological transformation rendering its ingestion more difficult. Predation on Euplotes is reduced when an alternative prey, the flagellate Chlorogonium elongatum, is available. Lower predation is accompanied by reduced induction in Euplotes.

2. We quantified the motility of both ciliates in the presence and absence of Chlorogonium to test the hypothesis that the differential response in Euplotes is a consequence of behavioural changes affecting the encounter rate of the prey and the predator.

3. The results indicate that S. mytilus uses different feeding strategies for each prey. It is a filter feeder when small food particles (Chlorogonium) are abundant, however, it becomes a raptorial feeder when large prey with an escape capability (Euplotes) is available and small alternative prey are absent.

4. As the mobility of filter feeding Stylonychia is strongly limited, the presence of the flagellate may indirectly affect the defence level in Euplotes by reducing the frequency of contacts with the predator.

5. An experiment with Chaetogaster diastrophus, a more specialised predator not affected by the presence of Chlorogonium, as well as direct manipulation of the encounter rate by changing the surface area available for the crawling ciliates, supported the encounter rate hypothesis.
The distributions of larval and juvenile fishes in Amazonian rivers of different nutrient status
Authors: De Lima Álvaro Carvalho , Araujo‐Lima Carlos A. R. M.
Published: May 2004

1. Previous work has indicated, at least in two river systems, that some Characiformes species migrate from nutrient‐poor rivers to spawn in nutrient‐rich rivers. In the present work, larval and juvenile fish were surveyed to index spawning activity in order to determine whether this spawning pattern is repeated in nine major tributaries of the Amazon basin.

2. Adult Mylossoma aureum, M. duriventre, Colossoma macropomum, Anodus elongatus, Triportheus elongatus, Brycon cephalus, Semaprochilodus insignis, S. taeniurus and Prochilodus nigricans were recorded in nutrient‐poor and nutrient‐rich rivers. However, larval and juvenile individuals of these species were found in nutrient‐rich rivers only, indicating that spawning activity was restricted to that river type.

3. Concentration of suspended solids in the river was correlated with total ichthyoplankton density and related to species composition of juvenile characiform assemblages.

4. Our findings reinforce the hypothesis that nutrient‐rich rivers and associated floodplains function as spawning and nursery grounds, and suggest that they function as source habitats for these species in the Amazon Basin.
Site‐occupancy in relation to flight‐morphology in caddisflies
Authors: Hoffsten Per‐Ola
Published: May 2004

1. The relationship between morphology and site‐occupancy provides opportunities to infer differences in dispersal and flight ability, but empirical data for aquatic insects is limited.

2. In this study, 17 species of caddisflies from 10 families were collected from springs, streams and lakes, and total body mass, relative thorax mass, relative wing area (wing loading), and the aspect ratio of the fore and hind wings (combined) were measured.

3. Partial least‐squares regression analysis of two independent distributional data sets produced significant models within which total body mass, relative thorax mass and wing loading were positively associated with site‐occupancy, whereas aspect ratio was negatively associated with site‐occupancy.

4. These results suggest that the faunal composition of streams is influenced by species dispersal abilities.
The dark‐colour‐inducing neurohormone of locusts: strain‐dependent and phase‐independent effects on adults of the migratory locust, Locusta migratoria
Authors: Grach Constantin , Yerushalmi Yoram , Inlow Mark , Pener Meir Paul
Published: May 2004

Abstract.  An albino strain that had originated from Okinawa, Japan, and a normally coloured strain that had originated from West Africa, were used to study the darkening response to injection of graded doses of dark‐colour‐inducing neurohormone of locusts (DCIN) ([His7]‐corazonin) of gregarious and solitarious adults of the migratory locust, Locusta migratoria (L.). By repeated crossings, congenic albinos and normal phenotypes were obtained, both with a 99.6% West African genome, and their darkening response was compared with the original Okinawa and West African strains. Within each of these four strains, no difference was found in DCIN‐induced darkening between gregarious and solitarious adults despite previous publications in the literature claiming an absence of ‘fire‐darkening’ in gregarious adults of this species. Okinawa albino adults showed a markedly higher darkening response than the other three strains, including albinos with a 99.6% West African genome. This finding demonstrates that the differential darkening response of the Okinawa albinos is caused not by albinism, but by the geographical origin (Okinawa) of the strain. This is the first report of geographical‐strain‐dependent differences in the response of an insect to a neurohormone. The darkening response of adults reached a maximum on day 10 after injection; subsequently, the dark colour faded slowly. Adults injected 1 day after their moult showed a greater darkening response than those injected after 14 or 28 days.
Food‐dependent regurgitate effectiveness in the defence of grasshoppers against ants: the case of bracken‐fed Abracris flavolineata (Orthoptera: Acrididae)
Authors: Calcagno Maria Pia , Avila Jorge Luis , Rudman Ibis , Otero L. Daniel , Alonso‐Amelot Miguel E.
Published: May 2004

Abstract.  The deterrence of a grasshopper, Abracris flavolineata, regurgitate against the fire ant, Solenopsis geminata, depends on diet. The ant deterrence of oral discharges of bracken‐fed insects is greater than for those feeding on lettuce. A water extract of Pteridium caudatum fronds is also more potent in deterring the ants than a lettuce extract. A positive correlation between the content of phenolics in the regurgitate and deterrence is observed and bracken‐derived oral fluids contain a 4.6‐fold higher content of phenolics than lettuce‐derived material. Nevertheless, no statistical difference is observed in condensed tannins content. The rate of transformation of bracken phenolics in the digestive tract of A. flavolineata proceeds quickly because, after only 48 h of discontinuing the diet, 53% of phenolics and 94% of tannins relative to the total present in the fronds are no longer in the ejected digestive fluid. It is suggested that this reduction may be a mechanism by which one fraction of the phenolics is metabolized or excreted and the other is used as defence via the oral secretion. The powerful deterrence index of bracken water extract indicates that other active secondary metabolites may also be present.
Effects of chronic exposure to a toxic prey in a generalist predator
Authors: Fisker Eva Nølke , Toft Søren
Published: May 2004

Abstract.  Generalist predators experience large differences in prey quality, and eating toxic prey may affect their fitness even if the toxic prey constitutes only a small fraction of a mixed diet. Feeding and life history parameters were examined in the wolf spider Pardosa prativaga during continuous exposure to the toxic collembolan Folsomia candida. Spiderlings were divided into a control group fed adult Drosophila melanogaster, a group fed only F. candida, and a mixed diet group fed both types of prey. Folsomia candida reduced survival, developmental stage attained and growth rate of all exposed spiders. Spiders chronically exposed to F. candida increased their consumption of D. melanogaster compared to control spiders. Folsomia candida thus inhibited the utilization of the high‐quality food and/or increased the respiration rate. The intake of F. candida remained at a constant low level throughout the experiment, indicating that P. prativaga was unable to develop an absolute aversion against this prey. Half of the control group was also given the mixed diet after a large juvenile instar was attained. These spiders were not affected to the same extent as the newly hatched spiderlings, indicating an ontogenetically increased tolerance. Comparison of laboratory‐raised and field‐caught spiders confirmed that tolerance to F. candida was size‐dependent and thus not an induced response. A differential survival in the mixed diet group, based partly on maternal effects, indicated possible genetic variability in the physiological tolerance to F. candida.
Lipid mobilization and locomotor stimulation in Gryllus bimaculatus by topically applied adipokinetic hormone
Authors: Lorenz Matthias W. , Zemek Rostislav , Kodrík Dalibor , Socha Radomír
Published: May 2004

Abstract.  Walking activity of 3‐day‐old adult female Gryllus bimaculatus (de Geer) (Ensifera, Gryllidae) was measured over 24 h. A high level of locomotor activity during the scotophase was found, which was two‐ to three‐fold higher than that during the photophase. The titre of lipid in the haemolymph was relatively low 2 h after lights on, increased significantly 2 h after lights off, although, 2 h after lights on in the next photophase, the lipid titre had decreased to the basal level. Topical application of homologous Grybi‐adipokinetic hormone (AKH) (100 pmol in 20% 2‐propanol) led to a significant increase in haemolymph lipids, comparable with the maximal increase caused by injection of AKH (3 pmol in water). Topical application of AKH also stimulated locomotor activity in crickets (maximal stimulation 1.8‐fold with 100 pmol Grybi‐AKH). The results suggest that AKH penetrates the cuticle quickly. It is assumed that AKH stimulates locomotory activity at least in part via the increase of haemolymph lipid titres; however, the stimulation of locomotor activity via a direct neuromodulatory effect of AKH cannot be excluded.
Behavioural context regulates dual function of ultrasonic hearing in lesser waxmoths: bat avoidance and pair formation
Authors: Rodríguez Rafael Lucas , Greenfield Michael D.
Published: May 2004

Abstract.  Ultrasonic hearing in moths evolved to detect bat echolocation cries and has been co‐opted into the mating system of some species. Some moths evade or approach ultrasonic stimuli that overlap in their spectral and temporal features. The present study addressed the evaluation of ultrasonic stimuli by lesser waxmoths, a species in which ultrasonic hearing functions in bat evasion and pair formation. Playback experiments show that the role of different stimulus features varies with behavioural context. Flying moths have a single evasive response, which is performed mainly on the basis of pulse length and stimulus power: they dive upon hearing loud pulses ≥ 1 ms in length, and respond more strongly to high‐power stimuli above that pulse length. Female moths walking on the ground respond with positive phonotaxis mainly on the basis of pulse rate by orienting toward pulses delivered at rates ≥ 30 pulses s−1. Consequently, moths on the ground approach stimuli that elicit evasion when detected in flight. However, the different responses given to stimulus features by flying and walking moths match the distinguishing features of bat cries and conspecific males in both contexts. Stimulus evaluation, modified by behavioural context, gives lesser waxmoths the flexibility to show appropriate evasion or approach responses to stimuli that overlap in their features.
Reproductive responses to photoperiod and temperature by diapausing and nondiapausing populations of Sesamia nonagrioides Lef. (Lepidoptera − Noctuidae)
Authors: Fantinou Argyro A. , Perdikis Dionyssios CH. , Zota Konstantina F.
Published: May 2004

Abstract.  The influence of long‐ and short‐day cycles on ovipostion and egg hatch of the corn stalk borer, Sesamia nonagrioides were investigated at a range of temperatures. Oviposition was suppressed when insects are exposed to long days through their immature stages and then transferred to short days after mating. Moreover, mean oviposition and egg hatch increased from 15 to 27.5 °C, whereas oviposition declined significantly at 30 °C at both photoperiodic regimes. Females derived from a diapausing population exposed to long days after mating showed a significantly higher egg production compared to females derived from a nondiapausing population. However, when females from a diapausing population were left to oviposit under short days, fewer eggs were produced compared to those exposed to long days after mating. Thus, photoperiod appears to affect reproductive traits of this species in a quantitative manner. Larval diapause duration is positively correlated with fecundity of the adults. There is also a positive correlation between pupal weight of individuals derived from a diapausing population and the postdiapause fecundity of adults.