bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple parasites are driving major histocompatibility complex polymorphism in the wild
Authors: Wegner K. M. , Reusch T. B. H. , Kalbe M.
Published: March 2003

Parasite mediated selection may result in arms races between host defence and parasite virulence. In particular, simultaneous infections from multiple parasite species should cause diversification (i.e. balancing selection) in resistance genes both at the population and the individual level. Here, we tested these ideas in highly polymorphic major histocompatibility complex (MHC) genes from three-spined sticklebacks (Gasterosteus aculeatus L.). In eight natural populations, parasite diversity (15 different species), and MHC class IIB diversity varied strongly between habitat types (lakes vs. rivers vs. estuaries) with lowest values in rivers. Partial correlation analysis revealed an influence of parasite diversity on MHC class IIB variation whereas general genetic diversity assessed at seven microsatellite loci was not significantly correlated with parasite diversity. Within individual fish, intermediate, rather than maximal allele numbers were associated with minimal parasite load, supporting theoretical models of self-reactive T-cell elimination. The optimal individual diversity matched those values female fish try to achieve in their offspring by mate choice. We thus present correlative evidence supporting the ‘allele counting’ strategy for optimizing the immunocompetence in stickleback offspring.
A direct experimental test of founder-flush effects on the evolutionary potential for assortative mating
Authors: Regan J. L. , Meffert L. M. , Bryant E. H.
Published: March 2003

Founder-flush speciation models propose that population bottlenecks can enhance evolutionary potential for reproductive isolation. To test this prediction, we subjected bottlenecked (three-pair founder-flush) and nonbottlenecked populations of the housefly to 18 generations of selection for assortative mating. After the selection regime, we analysed videotaped courtship bouts in these lines to identify correlated responses to the selection protocol. The realized heritabilities for assortative mating for both the bottlenecked and nonbottlenecked treatments were very low, but still significant. The founder-flush populations had thus responded to selection as well as the nonbottlenecked populations, although not significantly greater (i.e. total increases in assortative mating were 9.6 and 8.6%, respectively). Multivariate analyses on the courtship repertoires found that, although both bottlenecked and nonbottlenecked treatments attained similar levels of assortative mating, the treatments exhibited different evolutionary solutions in their correlated responses. Specifically, the bottlenecked lines demonstrated a significantly more diverse set of evolutionary trajectories (i.e. significant shifts along the second principal component for courtship). This suggests that the bottlenecked lines had greater potential for the evolution of novel phenotypes as predicted by founder-induced speciation models. Our results, however, cannot distinguish whether the more variable evolutionary responses resulted from increased heritabilities in courtship components, reduced potential to follow the convergent evolutionary trajectories noted for the nonbottlenecked lines, or some combination of both general processes in determining the resultant multivariate phenotype.
Genetic variation in organisms with sexual and asexual reproduction
Authors: Bengtsson B. O.
Published: March 2003

The genetic variation in a partially asexual organism is investigated by two models suited for different time scales. Only selectively neutral variation is considered. Model 1 shows, by the use of a coalescence argument, that three sexually derived individuals per generation are sufficient to give a population the same pattern of allelic variation as found in fully sexually reproducing organisms. With less than one sexual event every third generation, the characteristic pattern expected for asexual organisms appear, with strong allelic divergence between the gene copies in individuals. At intermediary levels of sexuality, a complex situation reigns. The pair-wise allelic divergence under partial sexuality exceeds, however, always the corresponding value under full sexuality. These results apply to large populations with stable reproductive systems. In a more general framework, Model 2 shows that a small number of sexual individuals per generation is sufficient to make an apparently asexual population highly genotypically variable. The time scale in terms of generations needed to produce this effect is given by the population size and the inverse of the rate of sexuality.
Testing the link between the latitudinal gradient in species richness and rates of molecular evolution
Authors: Bromham L. , Cardillo M.
Published: March 2003

Numerous hypotheses have been proposed to explain latitudinal gradients in species richness, but all are subject to ongoing debate. Here we examine Rohde's (1978, 1992) hypothesis, which proposes that climatic conditions at low latitudes lead to elevated rates of speciation. This hypothesis predicts that rates of molecular evolution should increase towards lower latitudes, but this prediction has never been tested. We discuss potential links between rates of molecular evolution and latitudinal diversity gradients, and present the first test of latitudinal variation in rates of molecular evolution. Using 45 phylogenetically independent, latitudinally separated pairs of bird species and higher taxa, we compare rates of evolution of two mitochondrial genes and DNA–DNA hybridization distances. We find no support for an effect of latitude on rate of molecular evolution. This result casts doubt on the generality of a key component of Rohde's hypothesis linking climate and speciation.
Acute haemolytic transfusion reactions due to weak antibodies that in vitro did not seem to be clinically significant
Authors: Hoppe B. , Pastucha L. , Seltsam A. , Greinacher A. , Salama A.
Published: March 2003

Background and Objectives In the present article, we report on two patients with acute haemolytic transfusion reactions (AHTRs), and whom we were unable to transfuse, owing to alloantibodies that in vitro did not seem to be clinically significant.

Materials and Methods The patients were a 67‐year‐old male and a 64‐year‐old female, both of whom developed antibodies to red blood cells (RBCs) after repeat blood transfusions. Serological analyses were carried out using standard techniques.

Results Both patients developed an AHTR of the intravascular type following blood transfusions. Serological re‐examination revealed weakly reactive alloantibodies with anti‐JMH specificity in one patient, and with unclear specificity in the second. Rechallenging the patients with 15–30 ml of packed RBCs caused AHTRs, and blood transfusion became impossible in both cases.

Conclusion Weak alloantibodies that in vitro do not seem to be clinically significant may cause severe AHTRs.
Knowledge about blood donation among a sample of Thai university students
Authors: Wiwanitkit V.
Published: March 2003

Background and Objectives Blood banks in Thailand use only a voluntary donation system. Although this has been established for many years, the quantity of blood is still insufficient. Knowledge about blood donation and attitudes toward it are inadequate, especially in rural areas. The registry data of the National Blood Centre, Thai Red Cross Society, indicate that most voluntary blood donors are university students. The present study was therefore conducted among the students of Chulalongkorn University to assess their knowledge of voluntary, non‐remunerated blood donation.

Materials and Methods Four hundred students participated in this study. A self‐administered questionnaire and face‐to‐face interview on various aspects of blood donation were used for data collection.

Results Although most participants (80%) knew about blood donation, only 11% (44 subjects) had ever donated blood voluntarily. We found no significant correlation between demographic data (gender, age, educational level of subjects studied) and such knowledge or actual blood donation. Among the non‐donor respondents, fear (305 cases) was the most common reason for not donating blood.

Conclusions Greater knowledge about blood donation does not lead to donation. Therefore, specific campaigns are needed to convert this into actual voluntary donation.
Impact of donor arm skin disinfection on the bacterial contamination rate of platelet concentrates
Authors: Lee C. K. , Ho P. L. , Chan N. K. , Mak A. , Hong J. , Lin C. K.
Published: March 2003

Background and Objectives Despite improved methods for detecting bacterial contamination of blood products, bacterial sepsis remains a significant risk in blood transfusion. This study was undertaken to investigate whether adopting a different skin disinfection protocol could reduce the rate of bacterial contamination of platelet concentrates.

Materials and Methods Two skin disinfection protocols were consecutively used in the routine blood collection setting during two 10‐month periods: 0·5% cetrimide/0·05% chlorhexidine solution followed by 70% isopropyl alcohol (first 10‐month time‐period); and 10% povidone‐iodine followed by 70% isopropyl alcohol (second 10‐month time‐period). The rates of bacterial contamination of platelet concentrates were monitored by using a surveillance programme described previously.

Results The overall bacterial contamination rate in the first time‐period was 0·072%. After introduction of the povidone‐iodine and isopropyl alcohol protocol, the bacterial contamination rate decreased to 0·042% (relative risk reduction: −0·42; 95% confidence interval, −0·12 to −0·61, P= 0·009). There were no differences in the types of micro‐organisms identified (P = 0·7).

Conclusions Skin disinfection by povidone‐iodine and isopropyl alcohol is more effective than that by cetrimide/chorhexidine and isopropyl alcohol in reducing venepuncture‐associated contamination of platelet concentrates by skin flora. Our data indicate that the disinfection protocol should be used on a routine basis and such implementation should translate into a significant improvement in blood safety to patients receiving platelet transfusion.
Incorporation of an additional viral‐clearance step into a human immunoglobulin manufacturing process
Authors: Van Holten R. W. , Ciavarella D. , Oulundsen G. , Harmon F. , Riester S.
Published: March 2003

Background and Objectives Regulatory agencies have mandated that manufacturers of immunoglobulin products incorporate robust viral inactivation or removal steps into their purification processes. We evaluated the effectiveness of incorporating nanofiltration, a generic virus‐clearance step, into an existing plasma‐fractionation process for a human anti‐D immunoglobulin product.

Materials and Methods The nanofiltration process studied utilizes a 180 000‐molecular weight composite membrane with well‐defined pore distribution. To examine its viral‐clearance capability, diluted anti‐D immunoglobulin was spiked with high concentrations of human and animal model viruses and subjected to tangential‐flow nanofiltration during scaled‐down validation runs. Viral clearance by the membrane was determined by calculating log removal values in accordance with guidelines provided by US and European regulatory agencies.

Results Nanofiltration removed viruses of varying sizes and physical characteristics. For the three non‐enveloped viruses tested (porcine parvovirus, encephalomyocarditis virus and hepatitis A virus, sizes 18–30 nm), clearance was 3·3, 4·1 and > 5·1 log, respectively. For the three enveloped viruses (human immunodeficiency virus‐1, bovine viral diarrhoea virus and pseudorabies virus, 50–200 nm), a substantial 5‐log reduction was demonstrated. Product potency, purity and stability were unaffected.

Conclusion Tangential‐flow nanofiltration provides substantial virus‐removal capabilities for immunoglobulin preparations.
Alloimmunization to RhD antigen in RhD‐incompatible haemopoietic cell transplants with non‐myeloablative conditioning
Authors: Mijovic A.
Published: March 2003

Background and Objectives Following exposure to RhD antigen, anti‐D develops in up to 20% of RhD‐negative patients on chemotherapy, but seldom in the recipients of haemopoietic cell (HC) or solid‐organ transplants. Data on anti‐D formation come from HC transplants using myeloablative conditioning; no data are available for the non‐myeloablative HC transplants. The two types of transplant have a distinct isohaemagglutinin disappearance rate and different kinetics of post‐transplant red‐cell engraftment. The objective of the study was to analyse anti‐D formation in patients receiving non‐myeloablative transplants from RhD‐incompatible donors.

Materials and Methods Sixteen patients were analysed: nine RhD‐negative recipients of RhD‐positive haemopoietic cells; and seven RhD‐positive recipients of a graft from a RhD‐negative donor. Patients were sequentially tested for irregular antibodies, as well as donor/recipient chimerism by cytogenetics and analysis of DNA variable‐number tandem repeats.

Results Despite having received 7–499 ml of D‐positive red cells, none of the RhD‐negative recipients developed anti‐D. The median follow‐up was 202 days. By contrast, anti‐D was identified in one of seven RhD‐positive recipients of an RhD‐negative graft.

Conclusions Non‐myeloablative conditioning containing fludarabine and/or Campath 1H, with cyclosporin A given post‐transplant, effectively prevents anti‐D formation in RhD‐negative recipients of a RhD‐positive graft. However, anti‐D developed in an RhD‐positive recipient of an RhD‐negative graft, who was also exposed to RhD‐positive blood products before and after the transplant. Transfusion of RhD‐positive products should be avoided in such patients.
Paying for blood donations: still a risk?
Authors: Van Der Poel C. L. , Seifried E. , Schaasberg W. P.
Published: March 2003

It is presently disputed whether studies indicating a higher risk of infectious diseases among paid blood donors are lessons of the past, or still hold relevance. Comparative studies published between 1968 and 2001 were assessed for a possible trend of change in the relative risk for infectious disease markers between paid and unpaid blood or plasma donors. Studies reporting that paid donors had lower risk were found, but most studies, including recent ones, continued to report that paid donors have higher rates of infectious disease markers than unpaid donors. By log‐linear regression analysis of the relative risk estimates for infectious disease markers among paid and unpaid donors from 28 published data sets, evidence was not found to indicate that the difference in risk for infectious disease markers between paid donors and unpaid donors had diminished over time (P = 0·128, not significant). Paid donors are still more likely than unpaid donors to donate blood in the period during which infectious donations escape detection by blood‐screening tests (the ‘window‐period’). Therefore, paid donations have a higher risk that labile blood components (such as red blood cells and platelets) are infected. Additional safety measures for handling plasma donations, and the preparation, purification and viral‐inactivation steps employed for the production of plasma derivatives, may render the difference in infectious disease marker rates in donors irrelevant for plasma products. However, not all viruses are inactivated and paid donors were repeatedly found to have higher frequencies of markers for emerging agents. In a quality system, critical steps of the process should be addressed, and selection of the donor population is one of the first steps in this process. It is advised that blood establishments present yearly reports (with complete and raw data) to authorities on the incidence and prevalence of infectious disease markers among their donors as an ongoing surveillance on the ‘quality’ of their donor populations. Paid blood or plasma donors still have higher rates for infectious disease markers than unpaid donors.
The use of ultrapurified bovine hemoglobin solution in the treatment of two cases of presumed red maple toxicosis in a miniature horse and a pony
Authors: Vin Ron , Bedenice Daniela , Rentko Virginia T. , Paradis Mary Rose
Published: March 2003

Objective:To report the use of ultrapurified bovine hemoglobin (PBHg) in the treatment of red maple toxicosis in horses.

Summary:The use of PBHg in a miniature horse and a pony with clinical signs of red maple toxicosis is described. Initial treatment of the horses included blood transfusion in Case 1, and intravenous crystalloid fluids, nasogastrically administered mineral oil, and activated charcoal in both cases. Both cases received PBHg (16 and 11 ml/kg, respectively) when the hematocrit dropped below 10%. Clinical stabilization of the horses (reflected by improved vital signs and mucous membrane color, increase in PvO2, and increase in plasma hemoglobin) was temporary, lasting 12 and 42 hours, respectively. A whole blood transfusion was given 16 hours after the infusion of PBHg in Case 1 and 42 hours after the infusion of PBHg in Case 2. The horses were discharged on days 15 and 17, respectively. Both were stable on discharge and were reported to be doing well 1 month after discharge.

New information provided:Ultrapurified bovine hemoglobin is shown to be safe in the treatment of red maple toxicosis. Ultrapurified bovine hemoglobin infusion resulted in temporary improvement in oxygen (O2) delivery as assessed by clinical and laboratory parameters. The use of PBHg may provide an ‘oxygen bridge’ in an acute hemolytic crisis in the horse. It may allow additional time in the treatment of red maple toxicity for the acute hemolysis to subside and for metabolism of the toxin to occur, thus providing a more optimal environment for an effective whole blood transfusion.
Winter Hardiness, Frost Resistance and Vernalization Requirement of European Winter Oilseed Rape (Brassica napus var. oleifera) Cultivars within the Last 20 Years
Authors: Rapacz M. , Markowski A.
Published: March 2003

Cultivars of European winter oilseed rape cultivated in the second half of the 1970s and in the mid‐1990s were screened for their winter hardiness, frost resistance and vernalization requirement. A strong correlation between winter hardiness and frost resistance in both groups of rape has been noticed. Among oilseed rapes cultivated in the late 1970s, low erucic acid and particularly double zero cultivars were less winter hard than high erucic acid cultivars. Double zero cultivars were characterized by lower frost resistance and lower vernalization requirement. A significant correlation between vernalization requirement and both frost resistance and field survival has also been shown. Frost resistance of the 1990s (double zero) cultivars was higher than that of double low cultivars from the late 1970s. Their vernalization requirement was still small and did not correlate with either frost resistance or winter hardiness. It was concluded that reduction in the content of glucosinolates in the 1970s involved decrease in winter hardiness and vernalization requirement of cultivars. During the following 20 years winter hardiness of double low cultivars has been improved, but vernalization requirements have not changed. As a result no correlation between winter hardiness and vernalization requirement in contemporary canola cultivars has been observed.
Effect of High Temperature on Seedling Growth and Photosynthesis of Tropical Maize Genotypes
Authors: Karim M. A. , Fracheboud Y. , Stamp P.
Published: March 2003

Genotypic variability in relation to growth and photosynthetic CO2 assimilation rate (Pn) is well known for maize (Zea mays L.) under heat stress conditions. This study was, however, initiated to test whether genotypic growth variation is related to variations in individual leaf size, leaf extension rate (LER), and photosynthesis of the single leaf at high temperature. Six tropical maize genotypes selected from the International Maize and Wheat Improvement Centre (CIMMYT) with contrasting growth responses were grown for 9 days after emergence (DAE) in the first and for 15 DAE in the second experiment at 25/22 °C and 42/30 °C. High temperature caused a marked decrease in the growth parameters, and the genotypes showed high growth variations irrespective of temperature levels. Interestingly, genotypes did not follow a similar ranking in relation to biomass production between 9 DAE (heterotrophic growth phase) and 15 DAE (autotrophic growth phase) at 25/22 °C, but the pattern was similar at 42/30 °C. Total leaf area and daytime LER of leaves 2 (l2), 3 (l3), and 4 (l4) showed a tight correlation with biomass production at both temperatures, while the LER of the youngest leaf (l4) at night also showed the same correlation at 42/30 °C. A significant relationship between the areas l2 and l3 and biomass was observed only at high temperature and not at 25/22 °C. The Pn decreased markedly at high temperature and genotypic variability was pronounced. The genotypes maintained a similar ranking of Pn measured from l2 at 8 DAE and from l3 at 13 DAE under unfavourable conditions only and not at 25 °C. Of the six genotypes, F250 outperformed the others in relation to growth and Pn activity. A tight correlation between photosynthesis of different leaves and growth was detected at high temperature but not at the optimal temperature for growth. It is concluded that the areas l2 or l3, daytime LER and Pn, all measured at high temperature stress conditions, can be regarded as good indicators of the thermo‐tolerance of tropical maize genotypes at the seedling stage.
Effect of Deheading on Juice Quality Characteristics and Sugar Yield of Sweet Sorghum
Authors: Rajendran C. , Ramamoorthy K. , Backiyarani S.
Published: March 2003

A field experiment involving 10 sweet sorghum cultivars was undertaken to study the effect of panicle removal at anthesis on juice quality characteristics and sugar yield in sweet sorghum; control plants were left intact. The plants were harvested at grain maturity, and juice extracted from the millable stalk was analysed for sucrose contact (Pol percentage), brix and purity. Deheading treatment resulted in significant increases in millable stalk and sugar yields over those of the intact control plants. As a result of panicle removal, stem dry matter accumulation increased and side tillers were generated. The amount of juice extracted increased in the treated plants, but sucrose (Pol percentage), brix and purity levels in the juice were reduced in comparison with the intact plants.
Ionic Ratios and Crop Performance: II. Effects of Interactions amongst Vanadium, Phosphorus, Magnesium and Calcium on Soybean Yield
Authors: Olness A. , Palmquist D. , Rinke J.
Published: March 2003

Because vanadium (V) is easily reduced to a cationic form within plant cells, data from resin‐extraction of soil were analysed for evidence of interactions between V and the resin‐extractable concentrations of magnesium (Mg) and calcium (Ca) on soybean seed yield. Three varieties, 9091, 9061 and 704, were grown over a 3‐year period in a corn–soybean–wheat rotation. Surface soil samples (0–15 cm) were extracted with ion‐exchange resins, extracts were analysed by inductively coupled plasma methods (ICP), and the results were regressed against seed yield using SAS PROC STEPWISE analysis using forward selection, backward elimination and maximum R2 routines. The seed yield of each variety showed a correlation with a unique set of resin‐extractable concentrations of V, phosphorus (P), Mg and Ca, and the V:(V + P), Mg:(Mg + Ca), Mg:(Mg + 1000 V) and Ca:(Ca + 1000 V) ratios. Variety 9091 was most sensitive to the Mg:(Mg + Ca) ratio. Variety 9061 was most sensitive to extractable V and to the V:(V + P) ratio. Variety 704 was sensitive to extractable P, V and Ca and the Mg:(Mg + 1000 V) ratio. For variety 9091, Mg fertilization (not currently practised) may be an economical practice, whereas P fertilization of 704 may not be economical. Each regression technique varied slightly in identification of important factors in seed yield. Concentrations and ratios of resin‐extractable elements in soil provide insights into optimal genotype selection and possible management alternatives for a given soil.
Analysis of the Impact of Alfalfa Forage Production under Summer Water‐Limiting Circumstances on Productivity, Agricultural and Growers Returns and Plant Stand
Authors: Takele E. , Kallenbach R.
Published: March 2003

The trade‐off between summer water conservation from alfalfa production and the effects on plant growth, agricultural crop value, and grower returns in the low desert area (Imperial, Palo Verde, Parker and Yuma Valleys of California and Arizona) was analysed using an experimental plot in the Palo Verde Valley. The purpose was to provide a basis for evaluating water conservation decisions and policies. Four summer dry‐down periods (withdrawing water for a predetermined period) of 0 days (control), 35 days, 70 days, and 105 days were analysed. Our results show that whereas the various dry‐down periods would provide water conservation ranging from 254 to 944 million m3, the region would experience agricultural income decline by US $16 to US $73 million. For growers, benefits of dry‐down would be effective only if the water price exceeds US $0.045 m−3 in California and US $0.036 m−3 in Arizona. Also dry‐down would have possible adverse effects in the following areas including declines in plant stand density, long‐term productivity, service industry sales, employment and biological benefits of soil fertility and organic matter that is attributed by the alfalfa plant in which case agriculture’s and growers monetary losses could increase.
Interactive Effect of Seawater and Growth Bioregulators on Water Relations, Abscisic Acid Concentration and Yield of Wheat Plants
Authors: Aldesuquy H. S. , Ibrahim A. H.
Published: March 2003

Irrigation of wheat plants with seawater (10 and 25 %) led to a significant increase in free and bound ABA in leaves, especially at 25 %. The relative water content (RWC), particularly at 25 %, and water use efficiency of the seawater‐irrigated plants were lower than those of the control. Grain pre‐soaking in GA3, IAA or ABA reduced the levels of accumulated ABA (free and bound) resulting from seawater irrigation. The stress imposed by seawater generally reduced yield and yield components of wheat plants, and the effect was more pronounced at the higher level of seawater (25 %). Furthermore, seawater treatments decreased the carbohydrate content and increased the protein content of the developing grains. The effect of seawater treatments on ion concentration in the developing grains was not consistent. The application of growth bioregulators appeared to mitigate the effect of seawater salinity stress on wheat productivity. Gibberellic acid gave the best effect. The economic yield (grain yield) had a strong positive correlation with RWC, water use efficiency for grain yield, water use efficiency for biomass, plant height, shoot fresh and dry weights, grain number/main spike, kernel weight and harvest index.
Effects of Rate and Time of Potassium Application on Cotton Yield and Quality in Turkey
Authors: Gormus O.
Published: March 2003

Studies were conducted at Adana, in the Çukurova region of southern Turkey, to evaluate the effects of the rate and timing of application of soil‐applied potassium (K) on cotton (Gossypium hirsutum L.) in 1999 and 2000. Potassium rates of 0, 80, 160 and 240 kg K2O ha−1 were soil‐applied in single treatments (all at early boll development) or in split treatments (1/2 at first square and 1/2 at first white flower; 1/4 at first square, 1/4 at first white flower and 1/2 at early boll development). Data collected in the two years indicated that application of 160 kg K2O ha−1 produced significant differences in seed‐cotton yield, lint yield and boll weight compared with the untreated control. The best combination producing the greatest yield was application of 160 kg K2O ha−1 with all of the K soil‐applied at early boll development. Cotton yields did not respond to K fertilization above the rate of 160 kg K2O ha−1 under the production practices typically found in the region. For application of K at a rate of 240 kg K2O ha−1 there was a marked difference in fibre strength between years in this study, but micronaire and uniformity ratio were not different amongst K rates within each year. When the total amount of K was applied at early boll development, higher yields, boll weights and lint turnouts were obtained compared with split applications, but the single application did not have a large impact on fibre properties.
Defoliation Regime Effects on Accumulated Season‐long Herbage Yield and Quality in Boreal Grassland
Authors: Donkor N. T. , Bork E. W. , Hudson R. J.
Published: March 2003

Within boreal grasslands, little information exists on the effects of initial defoliation date, frequency, and intensity on accumulated herbage yield and quality. We investigated the effects of initial defoliation in May, June or July, at heights of 5, 10 or 15 cm, and repeated at 2‐, 4‐ or 6‐week intervals throughout the growing season. Harvested material was combined with year‐end residual biomass, and examined for herbage removed, crude protein (CP), crude protein yield (CPY) and neutral detergent fibre (NDF). Compared to single defoliated check plots, total, grass and forb dry matter (DM) yields were lower under repeated defoliation by 25, 38 and 17 %, respectively. The majority of total herbage produced was harvested in the spring clipping. Total, grass and forb DM yields peaked under moderate (10 cm) clipping. Total DM and grass biomass were maximized with long (6 week) recovery periods. In contrast, forb biomass was greatest with May defoliation followed by a 4‐week interval. While maximum grass CPY was found under 10‐cm defoliation, forb CPY peaked with early and moderate to intensive defoliation. These results indicate that season‐long herbage biomass, along with CPY, can be maximized in boreal grasslands through controlled defoliation.
A critical review of the value of genetic distance studies in conservation of animal genetic resources
Authors: Ruane J.
Published: March 2003

Introduction

There has been a veritable explosion of projects in recent years aiming to calculate genetic distances between domesticated breeds of animals and the number of such projects is still increasing. The extent of this can be appreciated by a glance at the recent proceedings of the 26th International Conference on Animal Genetics (ISAG 1998). All domesticated species are being targeted, using breeds from both developed and developing countries and projects are now almost exclusively based on microsatellite marker loci. Although the goal in a few cases is to provide insights into the history of animal domestication (see, for example, M acH
ugh et al. 1997; L
au et al. 1998), the most common justification for genetic distancing projects is their importance for helping the decision‐makers to identify genetically unique breeds so that they may be prioritized for breed conservation purposes (e.g. H
all and B
radley 1995; M
oazami‐G
uodarzi et al. 1997; C
rawford and L
ittlejohn 1998).

On a world‐wide basis there are roughly 3000 breeds and breed varieties of the seven major mammalian species – cattle, pig, sheep, goat, horse, donkey and buffalo (FAO 1995). Of those with population data, 23% are either endangered or critical (FAO 1995). In addition, in the current century it is estimated that at least 600 breeds have been lost (H all and R
uane 1993). On the poultry side, the picture is even worse as over half the breeds of the five major species (chicken, domestic duck, muscovy duck, goose and turkey) are thought to be endangered or critical (FAO 1995). At the same time, there is often a lack of even the most rudimentary information on many of these breeds. Basic phenotypic data, including approximate figures for population sizes, are currently available on only 50% of the world’s animal genetic resources (AGR) (H
ammond 1998).

There is therefore an urgent need to act now to prevent the rapid erosion of AGR. This is especially true for breeds in developing countries, where many will be lost without ever having been adequately characterized or studied (K& ouml;
hler‐R
ollefson 1997). However, resources (both in terms of available manpower and finances) are limited in this area and appropriate use of these resources is therefore of vital importance. Given the large amount of current activity in the area of genetic distancing of domestic breeds, the aim of this article is to critically examine the value that genetic distance projects have for breed conservation.
Estimation of heritability for hip dysplasia in German Shepherd Dogs in Finland
Authors: Leppänen M. , Mäki K. , Juga J. , Saloniemi H.
Published: March 2003

The heritability of hip dysplasia in the German Shepherd Dog was estimated by applying the animal model and the Restricted Maximum Likelihood (REML) method to a data‐set which consisted of the hip scores of 10335 dogs. Fixed effects of the model were the month and the year of birth, screening age, the panelist responsible for screening and the origin of the animal's sire. The litter and the breeder had only minor effects on hip joints. Heritability estimates were moderate (0.31–0.35). The moderate heritability, which was found in this study, enables a much better genetic gain in the breeding programme, if proper evaluation methods, such as BLUP animal model, and effective selection is used instead of phenotypic selection.
Construction of a canine bacterial artificial chromosome library for screening with PCR
Authors: Schelling C. , Schläpfer J. , Billault A. , Guziewicz K. , Gmür A. , Katmann I. , Pineroli B. , Colomb B. , Rickli O. , Wittwer C. , Piasecka A. , Dolf G.
Published: March 2003

We have constructed a canine bacterial artificial chromosome library amenable to PCR screening. The library consists of 96 768 clones and was initially screened with 112 microsatellites representing all canine chromosomes. For 87 primer sets (77%) one to seven positive superpools were identified. The library will be expanded by adding additional superpools in order to increase the genome coverage. Interested researchers can access the library following the rules published at http://www.dogmap.ch.
Effect of methanol on methanogenesis and fermentation in the rumen simulation technique (RUSITEC)
Authors: Neumann L. , Weigand E. , Most E.
Published: March 2003

Introduction  Major methanol sources in ruminant feeds are pectins esterified with methoxyl groups. Methanol can be released by pectin esterase activity of rumen bacteria (R
exova‐B
enkova and M
arkovic 1976). It has been detected in rumen fluid of cows in vivo and in vitro (V
antcheva et al. 1970, 1972). It is, however, not likely to accumulate in the rumen fluid since it can be readily used by methylotrophic organisms. Methanogenic archaebacteria such as Methanosarcina barkeri (H
utten et al. 1980; M&
uuml;
ller et al. 1986) are able to use methanol as energy and carbon source. Two equations have been reported for this conversion:

4CH4 → 3CH4 + CO2 + 2 H2O

(1)

CH3OH + H2 → CH4 + H2O

(2)

Methanogenesis from methanol has been shown to occur during in vitro fermentations with rumen fluid as inoculum (C
zerkawski and B
reckenridge 1972; P
ol and D
emeyer 1988). However, acidogenic micro‐organisms, such as Eubacterium limosum or Butyribacterium methylotrophicum, may also utilize methanol. In rumen fluid of sheep fed a molasses‐rich diet, Eubacterium limosum was the predominant methanol‐utilizing bacterium (G
enthner et al. 1981). Major products of these acidogenic methylotrophs are acetate and butyrate. These different fermentation end‐products, methane versus fatty acids, will affect the metabolizable energy content of feedstuffs that are rich in highly methoxylated pectins or other methyl group‐containing compounds.

The purpose of the present study was to investigate whether the rumen simulation technique (RUSITEC) would be a suitable model to evaluate the methanogenic or acidogenic potential of methanol during ruminal fermentation. The study focused on methane production, fermentation characteristics and methanol turnover. Fermentation traits included pH, redox potential, ammonia and volatile fatty acid production, and degradation of feed constituents.
Down‐regulation of GPx1 mRNA and the loss of GPx1 activity causes cellular damage in the liver of selenium‐deficient rabbits
Authors: MÜLLER A. S. , PALLAUF J.
Published: March 2003

The effects of 10 weeks of dietary selenium and/or vitamin E deficiency (< 0.03 mg Se and 1.5 mg vitamin E per kg diet) on body Se and vitamin E stores and on the down‐regulation of liver cellular glutathione peroxidase (GPx1) and plasma glutathione peroxidase (GPx3) were examined in growing female New Zealand White rabbits in comparison to Se (+ 0.40 mg Se/kg diet) and/or vitamin E (+ 150 I.U./kg diet) supplemented controls. Additionally plasma lactate dehydrogenase (LDH) activity, liver thiobarbituric acid‐reactive substances (TBA‐RS) and liver protein carbonyls were measured to assess the development of oxidative stress during an alimentary Se and/or vitamin E deficiency. Significantly decreased concentrations of Se and vitamin E in plasma (Se: − 70%; vitamin E: − 87%) and liver (Se: − 90%; vitamin E: − 95%) indicated an efficacious Se and vitamin E depletion of the rabbits within 10 weeks. GPx1 messenger RNA levels (GPx1 mRNA) in the livers of Se‐depleted rabbits were down‐regulated to 1/3–1/8 of the Se supplemented controls. GPx1 enzyme activity in the livers of Se‐deficient rabbits declined to 10% of the Se‐supplied control rabbits. A significantly elevated LDH activity in the blood plasma of Se‐ and vitamin E‐deficient rabbits indicated a general impairment of tissues. Markedly increased TBA‐RS concentrations and protein carbonyl contents in the livers of Se‐ and vitamin E‐deficient rabbits gave further evidence for severe oxidative damage of cellular lipids and proteins during an alimentary Se and/or vitamin E deficiency. Both a full expresssion of GPx1 attained by dietary Se supplementation and dietary vitamin E supply effected an almost complete protection against oxidative cellular damage of the liver.
Influence of high levels of vitamin E on semen parameters of cocks
Authors: Danikowski S. , Sallmann H.‐P. , Halle I. , Flachowsky G.
Published: March 2003

This study was an attempt to find whether the reproductive performance of cocks would be influenced by oral administration of different amounts of dietary vitamin E over a long period of time. For that purpose 60 cocks were divided into five dietary groups of 12 animals each, and supplemented with 0 (control group), 100, 1000, 10 000 or 20 000 IU α‐tocopherol/kg diet, respectively, over a period of 12 months. The effect on semen parameters and biochemical parameters measured in pooled semen samples and the weight of the testes were determined. The weight of testes decreased with increasing amounts of supplemented vitamin E. Volume, pH, colour, consistency and motility were not influenced by the diets, but density of ejaculate (sperm/μl), total amount of spermatozoa and morphology of sperm were significantly lowered by increasing amounts of supplemented vitamin E. The α‐tocopherol concentration in ejaculates increased significantly in relation to the diet whereas phospholipid content and thiobarbituric acid‐reactive substances (TBARS) of the semen samples decreased significantly with increasing vitamin E supplementation. The reproductive performance of cocks was negatively influenced by high doses of vitamin E although decreased TBARS indicated rising oxidative defence.
Is dispersal density‐dependent in carabid beetles? A field experiment with Harpalus rufipes (Degeer) and Pterostichus niger (Schaller) (Col., Carabidae)
Authors: Midtgaard F.
Published: March 2003

In order to investigate whether density affects dispersal, carabid beetles of two species, Harpalus rufipes (Degeer) and Pterostichus niger (Schaller), were released separately in six and two field enclosures, respectively. The enclosures were 4 m2 each and located in an oat field. The former species was released in seven densities, each with 12 replicates and the latter in five densities each with four replicates. Beetles leaving the centre of the enclosures were captured in pitfall traps along a 1 m wide strip of bare soil. Logistic models were fitted to the data. There were no significant effects of the density treatment variable on P. niger. For H. rufipes the best model was obtained by specifying the density treatment as a nominal variable. The deviance accounted for by this model was highly significant. There were, however, no consistent trends for either species with respect to the density treatment. The inclusion of climatic variables, the number of new beetles introduced at the onset of each trial, or the date of the trial did not improve the fit of any of the models. It is concluded that density did not significantly increase dispersal in the two species. It thus appears that a possible increase in behavioural interactions (i.e. interference competition) did not increase the dispersal in adults of the two species examined in this experiment.
Suppression of cotton leafworm Spodoptera litura, flower beetle Mylabris pustulata and red cotton bug Dysdercus cingulatus by Rhynocoris marginatus (Fabr.) (Het., Reduviidae) in cotton field cages
Authors: Ambrose D. P. , Claver M. A.
Published: March 2003

Abstract: Mass‐reared reduviid, Rhynocoris marginatus was released in large‐sized cotton field cages against three cotton pests, Spodoptera litura, Mylabris pustulata and Dysdercus cingulatus. Pest species were introduced into separate cages in the absence of other pests, parasitoids and predators. Control experimental cages without R. marginatus were maintained for each prey set up during the evaluation period. R. marginatus greatly reduced the infestation of S. litura (57.5%), M. pustulata (52.3%) and D. cingulatus (45.8%). The leaves, flower and boll damages (32%, 35% and 28% by S. litura, M. pustulata and D. cingulatus, respectively) and seed‐cotton yield loss (1.4, 1.6 and 1.25 times in S. litura, M. pustulata and D. cingulatus infested cages, respectively) were reduced by R. marginatus compared with such fields without R. marginatus. The field observations suggest this predator’s pest suppression and damage reduction efficacy.
Role of canopy height in the resistance of Lycopersicon hirsutum f. glabratum to Tuta absoluta (Lep., Gelechiidae)
Authors: Leite G. L. D. , Picanço M. , Lucia T. M. C. Della , Moreira M. D.
Published: March 2003

The objective of this work was to study the effect of plant canopy height on the resistance of the tomato species Lycopersicon hirsutum to the tomato leafminer Tuta absoluta. Determination of the levels of tridecan‐2‐one (2‐TD) and undecan‐2‐one (2‐UD) in L. hirsutum, as well as the leaf area, density and types of trichomes present in L. hirsutum and L. esculentum were made on apical, medium and basal parts of plant canopy. Correlation of these data were made with the following biological characteristics of T. absoluta: rates of oviposition and egg hatching; length of egg, larval and pupal stages; mortality of the larval and pupal stages; pupal weight; and sex ratio. Levels of 2‐TD on leaves of L. hirsutum increased from bottom to top of canopy. Tuta absoluta had higher oviposition and egg hatching, as well as lower mortalities and smaller larval and pupal periods in L. esculentum than in L. hirsutum. Longer pupal period and greater number of small and large mines of T. absoluta were verified in the apical and medium parts of L. hirsutum plants. On the other hand, higher pupal mortality and longer larval periods were obtained in the apical and basal parts of the L. hirsutum plants. Larval mortality was higher in the basal part of those plants. In L. esculentum, leaves from the apical part of the plant promoted lower mortality, longer larval period and greater number of large mines of T. absoluta. However, a shorter pupal period was verified on leaves of the basal part. It appears that an increase in glandular trichome density in L. hirsutum leads to an increase in the levels of 2‐TD, which, in turn slows down larval development.
Larval aggregation and competition for food in experimental populations of Chrysomya putoria (Wied.) and Cochliomyia macellaria (F.) (Dipt., Calliphoridae)
Authors: Reis S. F. dos , Von Zuben C. J. , Godoy W. A. C.
Published: March 2003

In blowflies, larval aggregation in patches of food can be both intra‐ and interspecific, depending upon the degree to which competitors are clumped among the patches. In the present study, the implications of spatial aggregation for larval competition was investigated in experimental populations of the introduced blowfly Chrysomya putoria and the native Cochliomyia macellaria, using data from survival to adulthood in a range of single‐ and double‐species larval cultures. The reduction in C. macellaria survival rate in the presence of C. putoria suggests that the former species is the inferior competitor. The results on survival to adulthood for both species in single‐ and double‐species cultures can be explained in the light of the relationship between the level of intra‐ and interspecific aggregation and the efficiency of the larval feeding process. The possible implications of these results for the population biology of both species in natural environments are discussed.
Biology and control of Dicladispa gestroi Chapuis (Col., Chrysomelidae)
Authors: Delucchi V.
Published: March 2003

The beetle Dicladispa gestroi is known only from Madagascar, where it is considered to be a pest of rice. Research were carried out from 1885 to 1994 in the Alaotra lake region, the main rice‐producing area of the country, characterized by a warm rainy season from October to April and a cool dry season from April to October. The adult beetles invade the rice nurseries and the first direct‐seeded fields at the beginning of the rainy season; they have a gregarious behaviour and their feeding activity, together with the mines bored by the larvae, determines a change of colour from green to pale yellow in the damage areas, which resemble outbreak areas of rice leafhoppers. Oviposition takes place only on young rice plants in the tillering stage. Females emerging after the end of February enter a reproductive diapause and leave the rice fields to ‘hibernate’. Temperature summations for the egg, larval, and pupal development, as well as for the preoviposition period have been calculated. There is no yield loss up to a larval density of 0.6 per leaf and this economic injury level is seldom exceeded in the Alaotra lake region. Life tables carried out under field conditions show that chalcid parasitoids are the main mortality factor and are responsible for the collapse of entire outbreak areas. Since the discovery of the rice yellow mottle virus in 1989 in the Alaotra lake region and the disease transmission by chrysomelids, the pest status of D. gestroi has changed and control measures have to be applied. However, to avoid interference with the action of the parasitoids, chemical applications should be limited to rice nurseries.