bluuebunny/crossref_metadata_2025 huggingface dataset:
Close relatedness between mitochondrial DNA from seven Anser goose species
Authors: Ruokonen  , Kvist  , Lumme
Published: March 2003

The phylogenetic relationships of seven goose species and two of the subspecies representing the genus Anser were studied by approximately 1180 bp of mitochondrial DNA tRNAglu, control region and tRNAphe sequences. Despite obvious morphological and behavioural affinities among the species, their evolutionary relationships have not been studied previously. The small amount of genetic differentiation observed in the mitochondrial DNA indicates an extremely close evolutionary relationship between the Anser species. The sequence divergences between the species (0.9–5.5%) are among the lowest reported for avian species with speciation events of Anser geese dating to late Pliocene and Pleistocene. The species grouped into four mtDNA lineages: (1) snow and Ross’ goose, (2) greylag goose, (3) white-fronted goose, and (4) bean, pink-footed and lesser white-fronted goose. The phylogenetic relationships of the most closely related species, bean, pink-footed and lesser white-fronted goose, indicate a period of rapid cladogenesis. The poor agreement between morphological relationships and the phylogenetic relationships indicated by mtDNA sequences implies that either ancestral polymorphism and lineage sorting, hybridization and introgression or convergent evolution has been involved.
Fitness-consequences of geitonogamous selfing in a clonal marine angiosperm (Zostera marina)
Authors: Reusch T. B. H.
Published: March 2003

Plant mating systems have received considerable attention because the proportion of selfed vs. outcrossed progeny is an important evolutionary factor. In clonally reproducing plants, geitonogamous selfing between distant ramets belonging to the same genet is expected to be widespread, yet empirical data are sparse. Nothing is known about between-ramet selfing in aquatic flowering plants with subaqueous pollen transfer, most of which display pronounced clonal reproduction. From two locations in the western Baltic Sea, I present data on the effects of patch isolation and clonal diversity on the outcrossing rate of eelgrass, Zostera marina L., based on the genotypes of maternal plants and recently fertilized ovules scored at eight microsatellite loci. There were no differences in outcrossing rates between vegetation patches and continuous meadow although patches were nearly always composed of single genets. Quantitative effects of clonal diversity were present in the continuous vegetation where a significant positive correlation between genet diversity and the proportion of outcrossed offspring was detected (Kendall’s τ=0.82, P=0.0017). On a population-scale as well, the genotypic diversity was positively correlated with outcrossing. The relative fitness of selfed offspring was low (ω ± 95% confidence interval=0.56 ± 0.032 and 0.322 ± 0.15) indicating that geitonogamy incurred substantial fitness costs. Selfing rates in Z. marina may not be in evolutionary equilibrium because of spatial and temporal heterogeneity of clonal size and diversity. The high prevalence of dioecy in seagrasses may have evolved to avoid the fitness costs associated with geitonogamy.
Direct and correlated responses to selection for larval ethanol tolerance in Drosophila melanogaster
Authors: Fry J. D.
Published: March 2003

Ethanol is an important larval resource and toxin for natural Drosophila melanogaster populations, and ethanol tolerance is genetically variable within and among populations. If ethanol-tolerant genotypes have relatively low fitness in the absence of ethanol, as suggested by the results of an earlier study, genetic variation for ethanol tolerance could be maintained by variation in ethanol levels among breeding sites. I selected for ethanol tolerance in large laboratory populations by maintaining flies on ethanol-supplemented media. After 90 generations, the populations were compared with control populations in egg-to-adult survival and development rate on ethanol-supplemented and unsupplemented food. When compared on ethanol-supplemented food, the ethanol-selected populations had higher survival and faster development than the control populations, but on unsupplemented food, the populations did not differ in either trait. These results give no evidence for a ‘trade-off’ between the ability to survive and develop rapidly in the presence of ethanol and the ability to do so in its absence. The effect of physiological induction of ethanol tolerance by exposing eggs to ethanol was also investigated; exposing eggs to ethanol strongly increased subsequent larval survival on ethanol-supplemented food, but did not affect survival on regular food, and slowed development on both ethanol-supplemented and regular food, partly by delaying egg hatch.
Effects of assay conditions in life history experiments with Drosophila melanogaster
Authors: Ackermann M. , Bijlsma R. , James A. C. , Partridge L. , Zwaan B. J. , Stearns S. C.
Published: March 2003

Selection experiments with Drosophila have revealed constraints on the simultaneous evolution of life history traits. However, the responses to selection reported by different research groups have not been consistent. Two possible reasons for these inconsistencies are (i) that different groups used different environments for their experiments and (ii) that the selection environments were not identical to the assay environments in which the life history traits were measured. We tested for the effect of the assay environment in life history experiments by measuring a set of Drosophila selection lines in laboratories working on life history evolution with Drosophila in Basel, Groningen, Irvine and London. The lines measured came from selection experiments from each of these laboratories. In each assay environment, we measured fecundity, longevity, development time and body size. The results show that fecundity measurements were particularly sensitive to the assay environment. Differences between assay and selection environment in the same laboratory or differences between assay environments between laboratories could have contributed to the differences in the published results. The other traits measured were less sensitive to the assay environment. However, for all traits there were cases where the measurements in one laboratory suggested that selection had an effect on the trait, whereas in other laboratories no such conclusion would have been drawn. Moreover, we provide good evidence for local adaptation in early fecundity for lines from two laboratories.
Lateral plate asymmetry, diet and parasitism in threespine stickleback
Authors: Reimchen T. E. , Nosil P.
Published: March 2003

Individuals with random left–right departures from bilateral symmetry are predicted to exhibit fitness reduction including increased parasitism. In an insular lake population of stickleback (Gasterosteus aculeatus) from the Queen Charlotte Islands, Western Canada, phenotypes with high or low number of lateral bony plates exhibited increased plate asymmetry relative to modal phenotypes. Asymmetric lateral plate phenotypes had increased prevalence and to a lesser extent intensity of parasitism relative to symmetric individuals, suggesting that differences in genetic resistance to pathogens contributed to unequal parasitism. The effect occurred mainly in the larger adults and during the warmest season, which may be due to the high metabolic costs incurred during the summer breeding season. Dietary differences between symmetric and asymmetric phenotypes were also detected and could contribute to unequal infection rates by mediating exposure to infected prey items. Our study, which is one of the first long-term field assessments of asymmetry and parasitism, yields results that are consistent with studies linking asymmetry to reduced fitness and indicate that lateral plate asymmetry can be an indicator of poor individual quality, despite its apparent directionality.
Interaction of a host plant and its holoparasite: effects of previous selection by the parasite
Authors: Koskela T. , Salonen V. , Mutikainen P.
Published: March 2003

If parasites decrease the fitness of their hosts one could expect selection for host traits (e.g. resistance and tolerance) that decrease the negative effects of parasitic infection. To study selection caused by parasitism, we used a novel study system: we grew host plants (Urtica dioica) that originated from previously parasitized and unparasitized natural populations (four of each) with or without a holoparasitic plant (Cuscuta europaea). Infectivity of the parasite (i.e. qualitative resistance of the host) did not differ between the two host types. Parasites grown with hosts from parasitized populations had lower performance than parasites grown with hosts from unparasitized populations, indicating host resistance in terms of parasite’s performance (i.e. quantitative resistance). However, our results suggest that the tolerance of parasitic infection was lower in hosts from parasitized populations compared with hosts from unparasitized populations as indicated by the lower above-ground vegetative biomass of the infected host plants from previously parasitized populations.
Fluctuating asymmetry, fecundity and development time in Drosophila: is there an association under optimal and stress conditions?
Authors: Woods R. E. , Sgrò C. M. , Hercus M. J. , Hoffmann A. A.
Published: March 2003

A number of studies have reported a significant negative association between fluctuating asymmetry (FA) of bilateral morphological traits and individual fitness traits, but almost all of these are unreplicated and based on small sample sizes using single trait estimates of FA. We therefore tested if there was a relationship between the FA of five bilateral traits and fecundity and development time in Drosophila in a multiple replicated experimental design. Stressed treatments were included to increase the variability of traits and to test whether associations among traits were affected by changes in the environment. Significant positive relationships were found between the size of wing characters and mean fecundity for the 5-day period and this relationship tended to be stronger in the stress treatments. No association was found between FA and mean fecundity for any of the traits measured. Similarly, a significant positive relationship was detected between wing trait size and development time but no association was detected between trait FA and development time. There were no differences between mean fecundity or development time of extreme asymmetry phenotypes compared with modal phenotypes. These results are discussed with reference to suggestions in the literature that FA can be used to estimate individual fitness.
Trade-offs to flight capability in Gryllus firmus: the influence of whole-organism respiration rate on fitness
Authors: Crnokrak P. , Roff D. A.
Published: March 2003

Wing dimorphism, where some macropterous long-winged (LW) individuals can fly whereas micropterous short-winged (SW) individuals cannot, is common in insects and believed to be maintained in part by trade-offs between flight capability and reproductive traits. In this paper we examine differences in whole-organism respiration rate between wing morphs of the sand cricket Gryllus firmus. We hypothesized that maintenance of the flight apparatus would result in elevated CO2 respired because of the high metabolic cost of these tissues, which, in turn, constrain resources available for egg production in females. As the trade-off involves calling behaviour in males, we predicted no equivalent constraint on organ development in this sex. We found female macropters (particularly older crickets) had significantly higher residual respiration rates than micropters. In males, we found only marginal differences between wing morphs. In both sexes there was a highly significant effect of flight muscles status on residual respiration rate, individuals with functional muscles having higher respiration rates. Both female and male macropters had significantly smaller gonads than micropters. Whole-organism residual respiration rate was negatively correlated with fecundity: macropterous females with high respiration rates had smaller gonads compared with macropterous females with lower respiration rates.
Impact of a population bottleneck on symmetry and genetic diversity in the northern elephant seal
Authors: Hoelzel A. R. , Fleischer R. C. , Campagna C. , Le Boeuf B. J. , Alvord G.
Published: March 2003

The northern elephant seal (NES) suffered a severe population bottleneck towards the end of the nineteenth century. Theoretical expectations for the impact of population bottlenecks include the loss of genetic diversity and a loss of fitness (e.g. through a disruption of developmental stability); however, there are few direct demonstrations in natural populations. Here, we report on the comparison of archive samples collected prior to and following the NES population bottleneck. Measures of genetic diversity show a loss of variation consistent with expectations and suggest a strong disruption in the pattern of allele frequencies following the bottleneck. Measures of bilateral characters show an increase in fluctuating asymmetry.
Are reward polymorphisms subject to frequency- and density-dependent selection? Evidence from a monoecious species pollinated by deceit
Authors: Castillo R. A. , Cordero C. , Domínguez C. A.
Published: March 2003

Most deceit-pollinated species involve floral dimorphisms characterized by the presence of rewarding male flowers and nonrewarding female flowers. It has been proposed that this polymorphism establishes the conditions for the action of frequency dependent selection (FDS). The tendency of foraging animals to aggregate in areas of high resource density suggests that pollination efficiency and fruit production may be positively influenced by flower density (density dependent selection, DDS). In this paper we offer a graphical model describing the effects of FDS and DDS on a monoecious species pollinated by deceit. We test the FDS and DDS assumptions and the predictions of the model using field observations and experimental populations of Begonia gracilis in which population sex ratio and flower density were controlled. We found a marked effect of both FDS and DDS on pollinator visitation, fruit-set, and on the probability of female flowers to setting fruits. We conclude that these two types of selection have had a strong influence on the evolution of deceit-pollinated species.
Interspecific variation in plumage colour among birds: species recognition or light environment?
Authors: McNaught Melinda K. , Owens Ian P. F.
Published: March 2003

The traditional explanation for interspecific plumage colour variation in birds is that colour differences between species are adaptations to minimize the risk of hybridization. Under this explanation, colour differences between closely related species of birds represent reproductive character displacement. An alternative explanation is that interspecific variation in plumage colour is an adaptive response to variation in light environments across habitats. Under this explanation, differences in colour between closely related species are a product of selection on signal efficiency. We use a comparative approach to examine these two hypotheses, testing the effects of sympatry and habitat use, respectively, on divergence in male plumage colour. Contrary to the prediction of the Species Isolation Hypothesis, we find no evidence that sympatric pairs of species are consistently more divergent in coloration than are allopatric pairs of species. However, in agreement with the Light Environment Hypothesis, we find significant associations between plumage coloration and habitat use. All of these results remain qualitatively unchanged irrespective of the statistical methodology used to compare reflectance spectra, the body regions used in the analyses, or the exclusion of areas of plumage not used in sexual displays. Our results suggest that, in general, interspecific variation in plumage colour among birds is more strongly influenced by the signalling environment than by the risk of hybridization.
The evolution of infertility: does hatching rate in birds coevolve with female polyandry?
Authors: Morrow E. H. , Arnqvist G. , Pitcher T. E.
Published: March 2003

Natural levels of infertility in many taxa are often remarkably high, amounting to a considerable fitness cost which one expects to be minimized by natural selection. Several mechanisms have been proposed as potential causes of infertility, including inbreeding depression, genetic incompatibilities and selfish genetic elements. Infertility may also be an inherent result of conflict over fertilization between the sexes in polyandrous species, either because too many sperm enter the egg or because of over-efficient barriers to such polyspermic fertilizations. We generated phylogenetic independent contrasts to examine the variation in hatching success for a maximum of 58 species of birds in relation to two measures of female polyandry. Hatching success varied enormously across species (range: 61–100%), with a mean of 12% of eggs failing to hatch, but was not related to either the rate of extrapair paternity or to relative testes size. Thus, the causes of this significant fitness cost remains unclear and merits further examination by evolutionary biologists.
Detection of punctuated equilibrium from molecular phylogenies
Authors: Bokma F.
Published: March 2003

The theory of ‘punctuated equilibrium’ hypothesises that most morphological change in species takes place in rapid bursts triggered by speciation. Eldregde and Gould postulated the theory in 1972, as an alternative to the idea that morphological change slowly accumulates in the course of time, a then common belief they dubbed ‘phyletic gradualism’. Ever since its introduction the theory of punctuated equilibrium has been the subject of speculation rather than empirical validation. Here I present a method to detect punctuated evolution without reference to fossil data, based on the phenotypes of extant species and on their relatedness as revealed by molecular phylogeny. The method involves a general mathematical model describing morphological differentiation of two species over time. The two parameters in the model, the rates of punctual (cladogenetic) and gradual (anagenetic) change, are estimated from plots of morphological diversification against time since divergence of extant species.
Mitochondrial DNA variation and the phylogeography of the grey partridge (Perdix perdix) in Europe: from Pleistocene history to present day populations
Authors: Liukkonen-Anttila T. , Uimaniemi L. , Orell M. , Lumme J.
Published: March 2003

For a phylogeographical analysis of European grey partridge (Perdix perdix) we sequenced 390 nucleotides of the 5′ end of the mitochondrial control region (CR) of 227 birds from several localities. The birds were divided into two major clades (western and eastern) which differed in control region 1 (CR1) by 14 nucleotide substitutions (3.6%). For estimation of the time of divergence, the whole CR of 14 specimens was sequenced. The major clades differed by 2.2%, corresponding to an estimated coalescence time of c. 1.1 million years. On CR1, 45 haplotypes were found. Western clade haplotypes were found in France, England, Germany, Poland, Italy and Austria. Eastern clade haplotypes were found in Finland, Bulgaria, Greece, and Ireland. One Finnish population and all Bulgarian and Irish populations were mixed, but only in Bulgaria was the mixing assumed to be natural. Nucleotide and haplotype diversities varied between populations, and both clades showed geographical structuring. The distribution of pairwise nucleotide differences in the eastern clade fitted the expectations of an expanding population. About 80% of the genetic structure in the grey partridge could be explained by the clades. The western clade presumably originates on the Iberian Peninsula (with related subtypes in Italy), and the eastern clade either on the Balkan or Caucasian refugia. Large-scale hand-rearing and releasing of western partridges have introduced very few mtDNA marks into the native eastern populations in Finland.
Evolutionary ecology of Datura stramonium: equal plant fitness benefits of growth and resistance against herbivory
Authors: Valverde P. L. , Fornoni J. , Núñez-Farfán J.
Published: March 2003

This study evaluated how natural selection act upon two proposed alternatives of defence (growth and resistance) against natural enemies in a common garden experiment using genetic material (full-sibs) from three populations of the annual plant Datura stramonium. Genetic and phenotypic correlations were used to search for a negative association between both alternatives of defence. Finally, the presence/absence of natural enemies was manipulated to evaluate the selective value of growth as a response against herbivory. Results indicated the presence of genetic variation for growth and resistance (1 – relative damage), whereas only population differentiation for resistance was detected. No correlation between growth and resistance was detected either at the phenotypic or the genetic level. Selection analysis revealed the presence of equal fitness benefits of growth and resistance among populations. The presence/absence of natural herbivores revealed that herbivory did not alter the pattern of selection on growth. The results indicate that both strategies of defence can evolve simultaneously within populations of D. stramonium.
Genetic variation of polygenic characters and the evolution of genetic degeneracy
Authors: Frank S. A.
Published: March 2003

The classical model of mutation–selection balance for quantitative characters sums the effects of individual sites to determine overall character value. I develop an alternative version of this classical model in which character value depends on the averaging of the effects of the individual sites. In this new averaging model, the equilibrium patterns of variance in allelic effects and character values change with the number of sites that affect a character in a different way from the classical model of summing effects. Besides changing the patterns of variance, the averaging model favours the addition of loci to the control of character values, perhaps explaining in part the recent observation of widespread genetic degeneracy.
Worker interests and male production in Polistes gallicus, a Mediterranean social wasp
Authors: Strassmann J. E. , Nguyen J. S. , Arévalo E. , Cervo R. , Zacchi F. , Turillazzi S. , Queller D. C.
Published: March 2003

The resolution of social conflict in colonies may accord with the interests of the most numerous party. In social insect colonies with single once-mated queens, workers are more closely related to the workers' sons than they are to the queens' sons. Therefore, they should prefer workers to produce males, against the queen's interests. Workers are capable of producing males as they arise from unfertilized eggs. We found Polistes gallicus to have colonies of single, once-mated queens, as determined by microsatellite genotyping of the workers, so worker interests predict worker male production. In colonies lacking queens, workers produced the males, but not in colonies with original queens. Thus worker interests were expressed only when the queen was gone. The high fraction of missing queens and early end to the colony cycle relative to climate so early in the season is surprising and may indicate a forceful elimination of the queen.
Species concepts and species reality: salvaging a Linnaean rank
Authors: Lee M. S. Y.
Published: March 2003

The validity of the species category (rank) as a distinct level of biological organization has been questioned. Phenetic, cohesion and monophyletic species concepts do not delimit species-level taxa that are qualitatively distinct from lower or higher taxa: all organisms throughout the tree of life exhibit varying degrees of similarity, cohesion, and monophyly. In contrast, interbreeding concepts delimit species-level taxa characterized by a phenomenon (regular gene flow) not found in higher taxa, making the species category a distinct level of biological organization. Only interbreeding concepts delimit species-level taxa that are all comparable according to a biologically meaningful criterion and qualitatively distinct from entities assigned to other taxonomic categories. Consistent application of interbreeding concepts can result in counterintuitive taxonomies – e.g. many wide polytypic species in plants and narrow cryptic species in animals. However, far from being problematic, such differences are biologically illuminating – reflecting differing barriers to gene flow in different clades. Empirical problems with interbreeding concepts exist, but many of these also apply to other species concepts, whereas others are not as severe as some have argued. A monistic view of species using interbreeding concepts will encounter strong historical inertia, but can save the species category from redundancy with other categories, and thus justify continued recognition of the species category.
Microarray technology: the future of blood testing?
Authors: Petrik J.
Published: March 2003

The increasing pace of development in molecular biological techniques during the last 10–15 years has had a direct effect on mass testing and diagnostic applications, including blood screening. Nucleic acid amplification techniques (NAT), usually based on the polymerase chain reaction (PCR), have been successfully applied to blood grouping and implemented recently in screening of blood donations for hepatitis C virus (HCV). The majority of microarray technologies involve an amplification step, yet the main benefits of this technology come from simultaneous analysis of thousands of analytes. Microarrays were developed to utilize the huge amount of information provided by genome projects, but they have clear potential in mass screening and diagnostics. The application of microarray technology may revolutionize blood testing, providing for the first time the prospect of an integrated platform for comprehensive donor and donation testing, replacing multiple individual assays. Design features of a blood‐testing chip and various technologies with potential application in this field are discussed in this review.
Automated blood‐mixing devices still fail to mix at low bleeding rates
Authors: De Korte D. , Veldman H. A.
Published: March 2003

Background and Objectives

The study evaluated mixing performance for various commercial blood‐mixing devices at different flow rates.

Materials and Methods

A glycerol solution with a density equal to blood was pumped into a blood bag (mounted on a mixer) that contained 70 ml of Toluidin Blue in citrate–phosphate–dextrose (CPD). After 500 ml of glycerol solution had been pumped into the blood bag, the bag was emptied in fractions and the absorbance at 640 nm of each fraction (expressed as percentage of mixture absorbance) was plotted against the fraction number.

Results

At a flow rate of 30 ml/min, the curves were very sigmoid, with high initial values that decreased during collection of the fractions. The absorbance values of the fractions collected later (after ≈ 250–300 ml) were 10–50% (i.e. percentage of absorbance for complete mixing) for the different mixers, indicating that the CPD solution was incompletely mixed with the incoming solution, resulting in a lower‐than‐expected ‘anticoagulant’ content for the fractions collected later. At a flow rate of 50 ml/min the mixing was improved, but only at 75 ml/min did all mixers show relatively good mixing. Manual mixing, by kneading the bag three times/min, gave at all rates an almost ideal mixing curve, 105% initially to 90% in the final fractions.

Conclusion

At relatively high bleeding rates, all mixers performed well, although complete mixing was only obtained with manual kneading. However, most blood‐mixing devices still fail to mix efficiently at normal and low bleeding rates. Although the minimal degree of necessary mixing is unknown, further optimization of mixing devices seems warranted.
Two cases of immune haemolytic anaemia, associated with anti‐piperacillin, detected by the ‘immune complex’ method
Authors: Arndt P. A. , Garratty G. , Hill J. , Kasper M. , Chandrasekaran V.
Published: March 2003

Background and Objectives Sera containing antibodies to penicillin and penicillin‐related drugs are typically thought to react with drug‐coated red blood cells (RBCs) (drug adsorption method), but not when the sera are added to drug and RBCs in the same tube (‘immune complex’ method). Two cases of immune haemolytic anaemia caused by anti‐piperacillin have been previously described. Serological details were given in only one patient. In that subject, the antibody was immunoglobulin (Ig)M + IgG and reacted by both the drug adsorption and ‘immune complex’ methods.

Materials and Methods Two patients with cystic fibrosis developed positive direct antiglobulin tests (DATs) and haemolytic anaemia after 11–12 days of piperacillin therapy. Serological studies were performed with piperacillin, Zosyn (piperacillin + tazobactam) and penicillin by using the drug adsorption and ‘immune complex’ methods.

Results The first patient's serum contained an IgG, complement‐activating anti‐piperacillin that reacted by the ‘immune complex’ method only. The second patient's IgM + IgG, complement‐activating anti‐piperacillin reacted by the ‘immune complex’ method and agglutinated piperacillin‐treated RBCs. An eluate from the patient's RBCs reacted weakly with all RBCs tested without the presence of drug. This patient had evidence of intravascular haemolysis and died.

Conclusions We describe the third and fourth examples of immune haemolytic anaemia caused by anti‐piperacillin; one was associated with fatal haemolytic anaemia. As piperacillin is commonly used in the treatment of cystic fibrosis, anti‐piperacillin should be considered whenever patients with cystic fibrosis develop haemolytic anaemia and/or positive DATs.
Pharmaco‐economics of blood transfusion safety: review of the available evidence
Authors: Van Hulst M. , De Wolf J. T. M. , Staginnus U. , Ruitenberg E. J. , Postma M. J.
Published: March 2003

Background and ObjectivesPharmaco‐economics provides a standardized methodology for valid comparisons of interventions in different fields of health care. The role of pharmaco‐economics in the safety of blood and blood products has, however, been very limited to date. This review discusses the pharmaco‐economic evaluations of strategies to enhance blood product safety that have been published in the scientific literature.

Materials and MethodsWe reviewed pharmaco‐economic methodology with special reference to cost‐effectiveness analysis. We searched the literature for cost‐effectiveness in blood product safety.

ResultNet costs per quality adjusted life‐year (QALY) gained varied from cost‐saving for human immunodefiency virus (HIV)‐ and hepatitis C virus (HCV) antibody screening and leucoreduction to several million $US per QALY gained for solvent–detergent treatment of plasma, nucleic acid amplification testing and HIV p24 antigen testing.

ConclusionsTo date the safety of blood transfusion has been largely determined by available technology, irrespective of pharmaco‐economics. Net costs up to several million $US per QALY gained were found for interventions implemented.
A second case of post‐transfusion purpura caused by HPA‐5a antibodies: successful treatment with intravenous immunoglobulin
Authors: Ziman A. , Klapper E. , Pepkowitz S. , Smith R. , Garratty G. , Goldfinger D.
Published: March 2003

Post‐transfusion purpura (PTP) is a rare disorder characterized by severe thrombocytopenia developing seven to 10 days following transfusion of platelet‐containing blood components, in a person who was previously sensitized via transfusion or pregnancy. Although most cases of PTP are caused by alloantibodies directed against HPA‐1a[(PlA1)], this case represents the second example of anti‐HPA‐5a‐associated PTP. A 61‐year‐old female was diagnosed with acute myocardial infarction and gastrointestinal bleeding and, after receiving six units of packed red cells over 5 days, developed PTP as a result of HPA‐5a [Br(b)] antibodies with severe thrombocytopenia (5000/µl). She was successfully treated with intravenous immunoglobulin (IVIG), suggesting that this is a highly effective mode of treatment for PTP, regardless of the antibody implicated.
Bread dough toxicosis in dogs
Authors: Means Charlotte
Published: March 2003

Objective: To provide information on the ingestion, and subsequent toxicity, of raw bread dough in dogs.

Case summary: A report from the ASPCA animal poison control center (APCC) files of 3 cases of ingestion of raw bread dough by dogs. Clinical signs included vomiting, ataxia, blindness, hypothermia, and recumbency. All dogs were successfully treated for ethanol toxicosis.

New information: Ingestion of bread dough can cause gastric obstruction, bloat, or ethanol toxicosis. The treatment of ethanol toxicosis, including decontamination, IV fluids, management of metabolic acidosis, and hypoglycemia is discussed. Yohimbine can be used in cases where the dog is comatose or has developed severe respiratory depression.
Use of non‐linear growth functions and calculation of relevant values
Authors: Warnstorff K. , Dörfel H.
Published: March 2003

Four sigmoid growth functions and two exponential functions are described. Relevant values are calculated for estimated functions and presented in tables. Six examples are presented and interpreted. Estimated functions and contour plots for the rate of relative growth are shown in figures. Functions are estimated with SAS 6.12 and STATISTICA 5.0.
The Endophyte Neotyphodium coenophialum Affects Root Morphology of Tall Fescue Grown under Phosphorus Deficiency
Authors: Malinowski D. P. , Brauer D. K. , Belesky D. P.
Published: March 2003

Mechanisms involved in mineral stress tolerance of cool‐season grasses infected by Neotyphodium spp. endophytes are not known. In a controlled‐environment experiment, two genotypes (DN2 and DN4) of tall fescue (Festuca arundinacea Schreb.) infected (E+) with their naturally occurring strains of N. coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin, and their non‐infected (E−) isolines were cultivated in nutrient solution at two phosphorus (P) levels of 31 mg P dm−3 (P+) and 0.31 mg P dm−3 (P−) for 3 weeks. Diameters of lateral roots, root hair length, and distance between root hairs were recorded using a digital image analysis system (Dage 72S CCD camera controlled by a Power MacIntosh 7200/120PC compatible computer equipped with an AG‐5 frame grabber board and NIH‐Image). Irrespective of tall fescue genotype and P level in nutrient solution, E+ plants had roots with a smaller diameter (16 %) than E− plants. In response to P deficiency, root diameter of E+ plants declined by 11 % and root hair length increased by 17 % when compared to E− plants. Altered root diameter and root hair length might be one of the mineral stress tolerance mechanisms in endophyte‐infected tall fescue.
Environmental Interactions between Different Tree Species and Mung Bean (Vigna radiata (L.) Wilczek) in Hedgerow Intercropping Systems in Sri Lanka
Authors: A. J. M. De Costa W. , Chandrapala A. G.
Published: March 2003

Annual crops grown in association with contour hedgerows often show yield reductions. This paper quantifies the variation of above‐ and below‐ground environmental factors in hedgerow intercrops involving six different tree species (Calliandra calothyrus, Desmodium ransonii, Flemingia c ongesta, Gliricidia sepium, Cassia spectabilis and Tithonia diversifolia) and thereby shows the effects of tree hedges on mung bean (Vigna radiata). Compared to a sole crop of mung bean, most hedgerow intercrops removed greater soil nitrogen, whereas all removed lower soil phosphorus. Mung bean closer to the hedgerows had lower N and P, indicating competitive capture of nutrients by hedges. Most hedgerow intercrops had greater top‐soil water because of their shading effect, especially near hedgerows. However, greater absorption by tree root systems decreased subsoil water near hedgerows late in the season. Soil temperature was lower in most hedgerow intercrops than in the control and increased with increasing distance from hedges. During initial stages of mung bean growth, radiation interception of intercrops was greater than that of the control, especially closer to hedgerows. However, after the first month, radiation interception of the sole crop was either equal to or greater than that of hedgerow intercrops. There was significant variation between tree species in all these environmental factors. Gliricidia, which allowed greater mung bean yields, also allowed greater nutrient capture by mung bean, greater top‐soil water availability, lower extraction of subsoil water and lower soil temperatures.
Effect of the Organic Residues of Miscanthus × giganteus on the Soil Organic Matter Level of Arable Soils
Authors: Beuch S. , Boelcke B. , Belau L.
Published: March 2003

During a complex investigation programme on the evaluation of the long‐term ecological impact of cropping Miscanthus, the substrate composition of residues in 4–8‐year‐old stands of Miscanthus × giganteus and the contribution of Miscanthus residues to soil organic matter (SOM) were investigated. Only about 50 % of the above‐ground biomass produced yearly was suitable for harvest because of pre‐harvest losses and harvesting residues. The potential supply to SOM was therefore 3.1 t ha−1 carbon annually accumulated by the litter, and 9.1 t ha−1 carbon accumulated by rhizomes and roots in the long term. These organic residues mineralized differently in laboratory experiments at generally high rates of decomposition. Analysis of soluble portions of the organic substance of these biomass components by hydrolysis with hot water, 2 % HCl and 80 % H2SO4 confirmed the results. Setting the SOM effect of an equivalent farmyard‐manure (FYM) supply to 100 %, Miscanthus residues reached 60 % (stubble, rhizomes), 80–90 % (pre‐harvest losses) and 100 % (roots). Established Miscanthus stands are able to produce about 8.2 t ha−1 organic substance, which is comparable with FYM in terms of SOM impact. This kind of calculation showed higher values for Miscanthus than for the agricultural crops investigated to date. An SOM increase of about 0.5 % on sandy soils and 0.2 % on silt soil was determined after 6–8 years of cropping Miscanthus × giganteus.
Note on the Effect of Non‐regular Spatial Patterns of Plants on Yield per Area Based on a Logarithmic Relationship between Single Plant Yield and Individual Area
Authors: Hühn M.
Published: March 2003

Based on several simplifying assumptions, a previously developed stochastic approach allows an estimation of the effects of non‐regular spatial patterns of the distribution of individual plants on yield per area (F). In this approach, two random variables were attached to each plant: single plant yield (E) and individual space per plant (A). The latter was estimated by the area of Thiessen‐polygons. Yield per area was calculated theoretically by the expectation of the ratio E/A. Based on a logarithmic relationship between E and A the expectation of E/A can be expressed by an approximation which depends on the mean and on the variance of the individual plant spaces. An improvement of this approximation can be easily obtained by including skewness and kurtosis of the distribution of individual plant areas. Finally, all theoretical concepts and results were applied to an experimental data set of winter oilseed rape (Brassica napus L.).
Contribution of White Clover Varieties in High‐Productivity Systems under Grazing and Cutting
Authors: Williams T. A. , Abberton M. T. , Evans D. R. , Thornley W. , Rhodes I.
Published: March 2003

Two medium leaf size varieties of white clover (Trifolium repens L.) were grown in mixture with a range of grass species and varieties in a field experiment conducted over 4 years. The clovers were grown singly or as a blend in swards with a tetraploid perennial ryegrass (Lolium perenne L.), a diploid Italian ryegrass (Lolium multiflorum L.) or tetraploid hybrids between these two species (Lolium x boucheanum Kunth). These grasses were also grown in monoculture. Swards were managed in a regime involving two periods of sheep grazing, two periods of cattle grazing and a silage cut in the same year for 4 years. The objectives of this experiment were 3‐fold: (1) to examine the yield and persistency of white clover in highly productive systems with modern perennial, hybrid and Italian ryegrasses; (2) to compare the performance of white clover varieties grown singly in mixture with grasses with their performance together as a blend, and (3) to examine the persistency of new Italian ryegrass varieties, exemplified by AberComo. The clover content of the sward remained high throughout the experiment, with a mean of 31 % overall. Differences in clover yield between plots were largely attributable to the effects of companion grasses. Total yields were very similar in plots containing different clover varieties and in plots where these varieties had been grown singly or as a blend. Grass yields in mixture were greater than those in monoculture but showed similar relative rankings. The diploid Italian ryegrass variety AberComo showed an unexpectedly high yield in the 4th year of the experiment. The implications of these results for strategies for productive, sustainable agriculture using modern white clover and ryegrass varieties are discussed.
Irrigation Decreases Loss of Leaf Nitrogen and Rubisco During Pod Development in Chickpea
Authors: Pandey R. , Sharma‐Natu P. , Ghildiyal M. C.
Published: March 2003

Chickpea (Cicer arietinum L., var. Pusa 256) plants raised under unirrigated and irrigated field conditions showed a decrease in leaf nitrogen and soluble protein content after flowering during pod development. This was found to be associated with a decrease in Rubisco content after flowering. Leaf nitrogen, soluble protein and Rubisco content, however, were higher in irrigated than in unirrigated plants. The Rubisco content at the flowering and post‐flowering stages was 29.43 and 16.59 %, respectively, of leaf soluble protein in unirrigated plants. Under irrigated conditions, the Rubisco content was 49.91 and 37.99 %, respectively, at the flowering and post‐flowering stages. These results therefore indicated a decrease in the mobilization of leaf nitrogen by irrigation in chickpea. The findings are discussed in relation to the decrease in seed yield and harvest index by irrigation commonly observed in this crop under north Indian conditions.
Growth and Yield of Cowpea as Influenced by Changes in Arbuscular Mycorrhiza in Response to Organic Manuring
Authors: Muthukumar T. , Udaiyan K.
Published: March 2003

We studied spore populations of arbuscular mycorrhizal (AM) fungi, mycorrhiza formation, and the growth and yield of cowpea [Vigna unguiculata (L.) Walp] grown in soils amended with sunnhemp (Crotalaria juncea L.), pongamia [Pongamia pinnata (L.) Pierre], cow dung and sheep manure. Spore populations and colonization of cowpea roots by AM fungi were higher in soils amended with organic manure than in non‐amended soils. The effects of organic amendment on cowpea growth, nutrient uptake and yield varied with the type of organic amendment. These responses to organic amendment were strongly related to changes in AM colonization levels and spore populations. Cowpea growth and yield were positively related to spore populations of Glomus aggregatum, G. geosporum and Scutellospora calospora, but were negatively correlated to spore populations of Acaulospora scrobiculata and G. sinuosum. We suggest that changes in the growth and yield of cowpea in response to organic amendment are a result of the differential effects of the types of amendment on the proliferation of different AM fungi within the community.
Agronomic Performance of Sorghum and Groundnut Cultivars in Sole and Intercrop Cultivation under Semiarid Conditions
Authors: Tefera T. , Tana T.
Published: March 2003

The performance of sorghum and groundnut cultivars was studied in sole cropping and intercropping systems at Babile in the semiarid area of eastern Ethiopia in 1996, 1997 and 1999. On average, late‐maturing cultivars of groundnut and sorghum gave higher dry pod yield and grain yield, respectively, when intercropped with early‐maturing cultivars of the associated crops. The significant variation among groundnut cultivars in yield and yield components under intercropping with sorghum cultivars revealed that sole cropping may not provide the appropriate environment for selecting varieties intended for use in intercropping. The productivity of intercropped groundnut and sorghum cultivars, as determined by total land equivalent ratios (LER), was higher than sole cropping, indicating the presence of temporal complementarity in the use of growth resources. A mean yield advantage of 32 % was obtained under intercropping.
Food, Feed, Fibre, Fuel and Industrial Products of the Future: Challenges and Opportunities. Understanding the Strategic Potential of Plant Genetic Engineering
Authors: Kern M.
Published: March 2003

Plants and plant crops have always been, and will continue to be, of vital importance for humankind. They are an essential source of food, feed, raw materials, energy and pleasure. One of the main concerns in agriculture has always been to improve the quality of seed. Today, at the beginning of the 3rd Millennium, agriculture is confronted with a wide range of complex challenges. With diminishing availability of farming land, climatic changes and the threat of declining water resources, the task is to meet the growing demand for food, feed, fibre, fuel, industrial products and products based on ‘functional’ plants. Future‐oriented, knowledge‐based and added‐value agriculture will have to become reality. This will mean reduced use and redisposition of resources – in other words, ‘Do more with less!’ Within this context, the possibilities offered by efficiency developments in conventional seed breeding, supported by gene technology and plant genomic research, will improve the prospects of being able to use our limited natural resources to best effect in the 21st Century. The appropriate use and timely development of these important aspects will ensure sustainable production of food, feed, fibre, fuel and industrial products in the future.
Diurnal and Seasonal Light Transmission to Cowpea in Sorghum–Cowpea Intercrops in Mali
Authors: Gilbert R. A. , Heilman J. L. , Juo A. S. R.
Published: March 2003

Tall cereal–short legume intercropping is ubiquitous in the semiarid tropics of West Africa, yet little is known regarding the dynamics of light interception in these systems. A field study was conducted in Cinzana, Mali, to characterize light transmission to cowpea in sorghum [Sorghum bicolor (L.) Moench]–cowpea [Vigna unguiculata (L.) Walp] intercropping systems. Different sorghum–cowpea planting configurations were used to examine photosynthetically active radiation (PAR) incident on the cowpea. The 4‐m tall sorghum cultivar CSM 219E intercepted > 60 % of incoming PAR from 2 m height to harvest (50 days). Consequently, total seasonal PAR received by intercropped cowpea was 60–66 % that of the unshaded monocrop. Thirty‐minute averages of PAR transmitted around solar noon had poor agreement (R2=0.53) with fractional daily light interception and overestimated seasonal PAR received by cowpea by 17 % in the north–south row orientation used. Thirty‐minute averages at 1100 h (R2=0.93) and 1430 h (R2=0.91) had the closest correlation to diurnal average PAR incident on cowpea. This study indicates that tall guineense sorghum captures significant amounts of light at low leaf area index (LAI) (< 2.0). Row orientation, time of measurement, plant height and LAI should be considered in calculating light interception in these intercropping systems.