bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Summary1. 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

Summary1. 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

Summary1. 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

Summary1. 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

Summary1. 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

Summary1. 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.
Estimates of genetic parameters for Boran, Friesian, and crosses of Friesian and Jersey with the Boran cattle in the tropical highlands of Ethiopia: milk production traits and cow weight
Authors: Demeke S. , Neser F. W. C. , Schoeman S. J. 
Published: May 2004

SummaryBreed additive and non‐additive effects plus heritabilities and repeatabilities for milk yield per lactation (LMY), milk yield per day (DMY), lactation length (LL), annual milk yield (AMY), annual milk yield per metabolic body weight (AMYBW) and cow weight at calving (BW) were estimated for 5464 lactation records collected from purebred Boran (B), Friesian (F), and crosses of Friesian and Jersey (J) breeds with the Boran breed raised in the tropical highlands of Ethiopia. Single trait analysis was carried out by using two equivalent repeatability animal models. In the first model the genotype was fitted as a fixed group effect, while in the second model the genotype was substituted by breed additive, heterotic and recombination effects fitted as fixed covariates. Both the F and J breed additive effects, measured as a deviation from the B breed were significant (p < 0.01) for all traits, except for BW of the J. The F and J additive contributions were 2774 ± 81 and 1473 ± 362 kg for LMY, 7.1 ± 0.2 and 4.8 ± 0.8 kg for DMY, 152 ± 7 and 146 ± 31 days for LL, 2345 ± 71 and 1238 ± 319 kg for AMY, 20.6 ± 0.9 and 18.9 ± 4.3 kg for AMYBW, and 140 ± 4 and −21 ± 22 kg (p > 0.05) for BW. The heterotic contributions to the crossbred performance were also positive and significant (p < 0.01) for all traits. The F1 heterosis expressed as a deviation from the mid‐parent values were 22 and 66% for LMY, 11 and 20% for DMY, 29 and 29% for LL, 21 and 64% for AMY, 42 and 42% for AMYBW, and 2% (p < 0.05) and 11% for BW for the F × B and J × B crosses, respectively. The recombination effect estimated for the F × B crosses was negative and significant for LMY (−526 ± 192 kg, p < 0.01), DMY (−3.0 ± 0.4 kg, p < 0.001), AMY (−349 ± 174 kg, p < 0.05) and BW (−68 ± 11 kg, p < 0.001). For the J × B crosses the recombination loss was significant and negative only for DMY (−2.2 ± 0.7 kg, p < 0.05) and BW (−33 ± 17 kg, p < 0.05). The direct heritabilities (h2) estimated for LMY, DMY, LL, AMY and AMYBW were 0.24 ± 0.04, 0.19 ± 0.03, 0.13 ± 0.03, 0.23 ± 0.04 and 0.17 ± 0.05, respectively. Based on the genetic parameters estimated, the best breeding strategy to increased milk production under highland Ethiopian conditions is to apply selection on purebred base populations (Boran and Friesian) and then crossing them to produce F1 dairy cows. However, for breeding decision based on total dairy merit, further investigations are needed for traits such as milk quality, reproduction, longevity and survival.
Investigating the turkey's ‘snood’ as a morphological marker of heritable disease resistance
Authors: Buchholz R. , Jones Dukes M. D. , Hecht S. , Findley A. M. 
Published: May 2004

SummaryThe sexual ornamentation of many wild species, including the ancestors of domestic poultry, are reliable indicators of parasite burden, suggesting that they may serve as morphological markers of heritable disease resistance. Measures of male ornamentation might be a culturally and economically feasible method of identifying conservation‐worthy genotypes from indigenous poultry flocks. Here we investigate the relationship between the sexually selected, parasite‐burden‐indicating ‘snood’ of male game farm turkeys, and their immunocompetence and immunogenetic [major histocompatibility complex (MHC) class II B restriction fragment‐length polymorphism (RFLP)] variation. We find that specific restriction fragments appear to be favourable to both immunocompetence and ornament size, but that turkey snood length is not a valuable predictor of wing web swelling due to phytohemagglutinin (PHA) injection. Immunocompetence increased with composite band sharing, a measure of absolute variation at the MHC. Snood length, however, was greatest in males that showed intermediate measures of relative band sharing. We conclude that tradeoffs among the conflicting demands on the energy reserves of free‐living poultry, might ensure that long‐snooded indigenous turkeys are best adapted to local disease conditions without wasting resources on hyperimmunity.
Evaluating response to selection and nutritional needs in a three‐way cross of rabbits
Authors: Costa C. , Baselga M. , Lobera J. , Cervera C. , Pascual J. J. 
Published: May 2004

SummaryAn experiment was carried out to evaluate the response obtained in a three‐way cross of rabbits when the lines involved had undergone within‐line selection for litter size or postweaning daily gain. The interaction between the level of nutrition and genetic level of the crossbreds was also studied. Using frozen embryos, old (H1) and current (H2) crossbred does and young were compared contemporarily. Does were fed a standard diet or a diet having high digestible energy and protein. The difference in the number of generations between lines used to produce both crosses were: 13 or 0 for the maternal lines, and 12 for the paternal line. The traits studied in the crossbred does were: daily feed intake during gestation, during the first 3 weeks of lactation and during the last week before weaning; doe weight at mating and at kindling; litter weight at birth and at weaning; total litter size, number born alive and litter size at weaning. The recorded traits for the young were: individual weight at weaning and at 63 days; individual daily gain after weaning; daily feed intake and feed conversion index. The last two traits were recorded as averages per cage. A total of 1161 litters from 190 does were involved. Significant differences in litter‐size traits, between H1 and H2 does, were observed and were higher than the expected from the within‐line response. The doe effect was not significant for other doe traits, adjusted to a constant litter size. The estimated difference in postweaning daily gain between H1 and H2 young was significant and in favour of H2, but the value was considerably lower than expected. The effect of type of feed and the interaction with the type of doe was not significant for any doe trait. The type of feed consumed by the doe was significant for postweaning daily gain, and the interaction with the type of crossbreds was significant for this trait and for individual weight at 63 days.
No major effect of the leptin gene polymorphism on porcine production traits
Authors: Szydlowski M. , Stachowiak M. , Mackowski M. , Kamyczek M. , Eckert R. , Rozycki M. , Switonski M. 
Published: May 2004

SummaryPorcine leptin gene (LEP) and its association with production traits was analysed in the Polish Large White (PLW, n = 135), Polish Landrace (PL, n = 120) and synthetic line 990 (L990, n = 184). Two fragments of exon 3 of LEP were studied with the use of RFLP and SSCP techniques. The frequencies of C allele for the T3469C polymorphic site were 0.11, 0.10 and 0.11 in PLW, PL and L990, respectively. Phenotypic data were collected for the average daily weight gain, the feed conversion ratio, the weight of abdominal fat, backfat thickness (five measurements), intramuscular fat, meat content, loin weight, loin muscle area, ham weight and ham cut weight. The contrasts between TT and TC genotypes at the T3469C polymorphic site were estimated in the unitrait Animal Model with genotype at the RYR1 locus included. The lowest p values occurred for association test between T3469C polymorphism and intramuscular fat content in PLW (0.26 ± 0.14%, p = 0.05) and loin weight in L990 (−0.32 ± 0.13 kg, p = 0.01). We conclude that the detected associations are population‐specific and the analysed polymorphism of the LEP gene does not contribute directly to genetic variability of growth and carcass traits in pigs.
Validating bovine sexed semen samples using quantitative PCR
Authors: Joerg H. , Asai M. , Graphodatskaya D. , Janett F. , Stranzinger G. 
Published: May 2004

SummaryIn cattle, separation of X‐ and Y‐bearing sperm cells by flow‐sorting technology makes it possible to predetermine the sex of calves. Due to high costs and decrease in fertilization, the extensive use of sexed semen in livestock depends heavily on sorting purity of sperm cells. Validating the accuracy of sperm sexing requires reliable procedures, therefore a real‐time polymerase chain reaction (PCR) assay was established to calculate the male cell proportion in the sexed semen based on the relationship between the amplification of a SRY fragment and an autosomal gene (MSHR) fragment. Our results showed stable amplification of SRY for 100–1 ng of genomic DNA, which allows detection of 1% of male cells if 100 ng of target DNA is used. To account for the discrepancy in the efficiency of the MSHR and the SRY amplification correction of the difference of the mean values was performed. The ratio of male to female sperm cells in unsexed semen cells was very accurately determined. The fractions of the sexed samples, however, were different from the expected range appearing lower than estimated. Thus, the study reveals that real‐time PCR provides a good basis for the examination of sexed sperm cells, but needs to be optimized for the samples.
The application of genetic markers for cell chimerism diagnosis in lambs
Authors: Rejduch B. , Kozubska‐Sobocińska A. , Radko A. , Rychlik T. , Słota E. 
Published: May 2004

SummaryA total of 181 Romanov lambs, including 84 pairs of twins, three litters of triplets and one litter of quadruplets, were investigated. Erythrocyte antigens belonging to six blood group systems were determined with 16 reagents. Six microsatellite loci BMS360, INRA123, McM42, CSSM66, ETH225 and TGLA53 were used to genotype the lambs with automated DNA sizing technology. For cytogenetic diagnosis of leucocyte chimerism, the fluorescence in situ hybridization (FISH) was applied using bovine X and Y chromosome painting probes. The blood‐group typing of lambs from twin and multiple pregnancies allowed us to detect nine cases of erythrocyte chimerism in the investigated population. The analysis of microsatellite DNA sequences showed the presence of cell chimerism in 13 animals. The hybridization of a bovine X and Y chromosome‐specific probe resulted in two yellow brightly luminescent signals in 54,XX cells, and one yellow and one blue signal in 54,XY cells helped us diagnose chromosomal chimerism in seven animals.
Two new SNPs within exon 1 of the porcine MYOD1 (MYF3) gene and their frequencies in chosen pig breeds and lines
Authors: Urbański P. , Kurył J. 
Published: May 2004

SummaryMyogenic factor 3 (MYF3, MYOD1) is a product of the MYOD1 gene, belonging to the MyoD gene family coding for the transcription factors which control the processes of myogenesis. Two fragments of exon 1 of the MYOD1 gene were amplified and sequenced. Two novel single nucleotide polymorphisms (SNPs), C489T and G566C, were identified in the fragment located between nucleotides 333 and 662. Transition C489T does not change the amino acid sequence (Leu), whereas transversion G566C leads to a replacement of arginine with proline at residue 76. Both SNPs were recognized with the BssSI restriction endonuclease. The distribution of alleles for both SNPs was tested in several pig breeds and lines raised in Poland (Polish Large White, Polish Landrace, Pietrain, Duroc, Zlotnicka Spotted, synthetic line L990). Duroc pigs proved homozygous at nucleotides 489 and 566 (haplotype T–C, respectively) and, compared with the remaining tested breeds (except for Zlotnicka Spotted), differed significantly in the frequency of alleles for both SNPs. The frequency of mutations C489T and G566C, observed among Zlotnicka Spotted pigs, was similar to that observed in the Duroc pigs and in the remaining breeds, respectively. As a result of the absence of polymorphism at both the nucleotides 489 and 566, Duroc pigs are not suitable for evaluating the effect of the SNPs identified in meat and carcass traits.
Is obesity a risk factor for psychopathology among adolescents?
Authors: Erermis Serpil , Cetin Nurcan , Tamar Muge , Bukusoglu Nagehan , Akdeniz Fisun , Goksen Damla 
Published: May 2004

Abstract
Background
: Although several studies have documented the existence of psychopathology in obese adolescents, disagreement remains regarding the extent and nature of this psychopathology. The aim of the present study was to explore the type and frequency of psychopathology in a clinical as well as a non‐clinical sample of obese adolescents, and in a normal weight control group.
Methods
: The study sample consisted of a clinical study group of 30 obese adolescents, a non‐clinical obese group of 30 obese adolescents, and a control group of 30 normal weight adolescents. Psychological assessment was performed using a non‐structured psychiatric interview, the Child Behavior Checklist (CBCL), Children Depression Inventory (CDI), Rosenberg Self‐esteem scale (SES) and the Eating Attitude Test (EAT).
Results
: More than half of the clinical obese adolescents (16/30) had a DSM‐IV diagnosis, often involving major depressive disorder (n = 10). The mean scores of anxiety‐depression, social problems, social withdrawal and total problem in the CBCL scale of the clinical obese group were significantly higher than the non‐clinical obese group and the normal weight control group. The mean total scores of the SES and the CDI of the clinical obese group were higher than the normal weight control group. The mean total score of EAT of the clinical obese group was significantly higher than the normal weight control group, and the mean score of EAT of the non‐clinical obese group was significantly higher than the normal weight control group.
Conclusions
: The results support previously published reports which show a higher ratio of psychopathology (depression, behavioral problems, low‐esteem) among clinical obese adolescents than among non‐clinical obese adolescents. Findings provided evidence for a psychosocial at‐risk population in a subgroup of obese adolescents.