bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen mineralisation indices in ferrosols under eucalypt plantations of North-Western Tasmania: association with previous land use
Authors: Wang XJ , Smethurst PJ , Holz GK
Published: April 2005

Potentially mineralisable N was studied in the laboratory and in the held in ferrosols from eucalypt plantations and pastures in north-western Tasmania. The plantation sites previously supported either Pinus radiata plantations (ex-pine), mixed eucalypt-myrtle forest (ex-mixed), or open Eucalyptus delegatensis forest with a grass understory (ex-dele). Ranges of concentrations of organic C and total N, and C to N ratio, were 6.9-13.6%, 0.297-0.978%, and 10.3-30.4, respectively. The concentration of organic C was independent of previous land use, but rankings for total N, anaerobically mineralisable N, and extractable N in hot KCl were pasture > to ex-dele = ex-mixed > ex-pine. The ratio C:N in theex-pine group (23.6) was higher than ratios in other groups (13.1-15.6). Anaerobically mineralisable N ranged from 49 to 214 �g/g, and was highly correlated with total N and extractable N in hot KCl at 95�C for 16 h (r = 0.83 for both cases, P < 0.001). The C:N ratio was negatively correlated with total N and anaerobically mineralisable N (r = 0.56 and 0.70, P < 0.01). The results indicated that the pasture soils had greater availability of mineral N, and that total N, C:N ratio, and anaerobically mineralisable N may provide useful information for assessing N mineralisation in these soils.
Soil nitrogen availability in the cereal zone of South Australia .2. Buffer-extractable nitrogen, mineralisable nitrogen, and mineral nitrogen in soil profile under different land uses
Authors: Xu ZH , Amato M , Ladd JN , Elliott DE
Published: April 2005

Mineral nitrogen (nitrate-N+ammonium-N) and its distribution in soil profiles to 60 cm depth at sowing in 3 growing seasons, 1990-1992, were assessed for 123 field experimental sites in South Australia. The sites were used to test N fertiliser responses with cereal crops following different land uses. More than 90% of the variation in mineral N at cereal sowing was attributable to nitrate-N in the 60-cm soil profiles. Coefficients of variation (CV) for nitrate-N ranged from 37 to 45%, less than half of the CV values (88-113%) for ammonium-N. More than 70% of mineral N in soil to 60 cm depth was accounted for by mineral N in the top 20 cm of soil, and 49% by mineral N in the top 10 cm of soil. The amounts of mineral N in the 60-cm soil profiles at sowing ranged from 24 to 180 kg N/ha (median 75) at sites following pastures, and from 22 to 113 kg N/ha (median 69) following grain legumes, significantly higher than 17 to 116 kg N/ha (median 47) following cereals. Only 26% of the variation in mineral N of soils (0-60 cm depth) could be predicted by soil total N, mineralisable N assessed by the aerobic incubation method, and previous land use. Ammonium-N extracted by phosphate-borate buffer from soils sampled at 0-10 and 10-20 cm depths was directly related to soil total N and N mineralised after soil incubation, but not to mineral N accumulating at sowing in the soil profiles to 60 cm depth. Utilisation of a soil containing 15N-labelled organic residues, and sampled to 100 cm depth at sowing in 5 successive growing seasons, revealed a positive relationship between the 15N atom% enrichments of soil profile mineral N, mineralisable N from soil incubations, and plant N. Enrichments of soil profile mineral N and plant N were almost identical. However, the enrichment of buffer-extractable ammonium-N was comparatively low and unresponsive to the time of soil sampling, and unrelated to the other soil and plant N pools. Thus, buffer-extractable N was unrepresentative of plant-available N.
Changes in soil chemical properties under long-term sugar cane monoculture and their possible role in sugar yield decline
Authors: Bramley RGV , Ellis N , Nable RO , Garside AL
Published: April 2005

Soil samples from paired 'old' and 'new' sugar cane soils from 6 contrasting sites in 3 climatically contrasting areas of North Queensland were analysed to identify changes in soil chemistry resulting from continuous sugar cane monoculture. The aim was to identify soil factors that may be associated with, or act as triggers to, the expression of sugar yield decline. It was found that there was no consistent effect of time under sugar monoculture on soil chemical properties across all sites, when either the distributions of properties through the soil profile, or property values at specific depths, were considered. However, marked effects were noted at some sites with respect to some soil properties, and the lack of consistent results across all sites may therefore be attributable to the inherent differences between the soils sampled. These effects were generally consistent with soil acidification.
Uptake of phosphorus from different sources by Lotus Pedunculatus and three genotypes of Trifolium Repens .1. Plant yield and phosphate efficiency
Authors: Trolove SN , Hedley MJ , Caradus JR , Mackay AD
Published: April 2005

The breeding of phosphate (P) efficient pastoral legumes could reduce the amount of fertiliser required on pastoral farms. In this study, Lotus pedunculatus and 3 genotypes of white clover (Trifolium repens L.) known to differ in their ability to respond to added P were grown on unfertilised soil and soil to which either monocalcium phosphate (MCP) or North Carolina phosphate rock (NCPR) were added. White clover genotype 8D (a selection line from Crau) had a greater (P < 0.05) internal P efficiency (shoot DM production per unit plant P) than 1A (a selection line from Gwenda) or lotus on unfertilised soil, whereas on fertilised soil, lotus had a significantly higher (P < 0.05) internal P efficiency than 2 of the white clover genotypes on MCP-fertilised soil (P < 0.01) and all 3 white clover genotypes on NCPR-fertlised soil (P < 0.01). Lotus also had a higher (P < 0.01) external P efficiency (total P uptake) than all 3 white clover genotypes on the 2 fertilised treatments. This was due to a greater root length, not a greater P uptake per unit length.
Biodegradation of 2,4-D herbicide as affected by Its adsorption-desorption behaviour and microbial activity of soils
Authors: Bolan NS , Baskaran S
Published: April 2005

The adsorption-desorption behaviour and the degradation of an ionic herbicide (2,4-D) were examined using 10 soils from New Zealand that differed in their organic matter and clay content. Adsorption isotherms for 2,4-D were adequately described by the Freundlich isotherm and the values of the exponent N of the Freundlich isotherm were close to 1 (0.92-0.98), indicating that the adsorption isotherm tended to become linear. The extent of adsorption, as measured by the distribution coefficient (Kd), increased with an increase in soil organic carbon. The rate of desorption of 2,4-D followed first-order reaction kinetics with respect to surface concentration, and decreased with an increase in the organic carbon content of the soils. The rate of degradation of 2,4-D, as measured by the half-life (t1/2), decreased with an initial increase in soil organic carbon, which is attributed to the increase in adsorption. With increasing adsorption, the rate of desorption decreased, resulting in a low concentration of 2,4-D in the soil solution that is available for microbial degradation. When the organic carbon content was more than 12%, however, both the adsorption and rate of degradation increased. The enhanced degradation of 2,4-D at these levels of organic carbon may be related to the increased biological activity of the soil, as measured by substrate-induced respiration, and the decreased 2,4-D-induced inhibitory effect on microbial activity.
A seasonal decomposition of the estimated size of a penguin population at Phillip Island, Australia
Authors: Yang H.-C. , Chambers L. E. , Huggins R. M.
Published: April 2005

Modern non-parametric methods allow the estimation of a population size under weaker conditions than the classical methods if there are frequent capture occasions. Here a non-parametric estimate of the number of penguins occupying Summerland Beach, Phillip Island, Australia, was computed. This estimator did not assume equal catchability of individuals, did not assume a parametric form for the population size as a function of time and allowed individuals to leave and re-enter the population. The resulting estimate was then decomposed into a seasonal component and a trend component using seasonal time series models to facilitate the understanding of the changes in the population size. The estimated seasonal effects quantified the difference between the number of penguins in the breeding and non-breeding season, and the trend component indicated an increase in the population size over the period of the study. The estimates of the number of penguins are shown to be consistent with other estimates obtained from a variety of sampling methods and statistical analyses.
Predator scent induces differing responses in two sympatric macropodids
Authors: Ramp Daniel , Russell Ben G. , Croft David B.
Published: April 2005

When prey species encounter the scent of a predator they must make a decision on how to respond. This may be either to ignore, flee, hide or alarm call. While many species are able to derive detailed information from the chemical cues associated with predator scent, for some the decision to respond is often made without being able to identify the actual location and intentions of the predator. Depending on the sociality and ecology of the species, it may pay to flee or to engage in predator inspection where knowledge is impure. We tested for this in two sympatric marsupial macropodids, the parma wallaby (Macropus parma) and the red-necked pademelon (Thylogale thetis), as little is known of how these species detect and respond to olfactory cues of predation risk. We observed that, when presented with a synthetic predator scent mimicking dog urine, the social forager, T. thetis, tended to spend more time close to the predator odour, while the solitary forager, M. parma, exhibited an aversive response. The results suggest that social and ecological constraints on the sensory modalities used in predator detection may influence how macropodids respond to olfactory predator cues.
Interplay between age class, sex and stress response in green turtles (Chelonia mydas)
Authors: Jessop Tim S. , Hamann Mark
Published: April 2005

We investigated plasma hormone profiles of corticosterone in green turtles (Chelonia mydas) in response to a capture stress protocol. Further, we examined whether age class and sex were covariates associated with variation in both basal corticosterone levels and the adrenocortical stress response of non-breeding green turtles. Green turtles responded to the capture stress protocol by significantly increasing plasma levels of corticosterone over an eight-hour period. Further, there was a significant effect of age class on the capacity for green turtles to produce corticosterone in response to a capture stressor, with juvenile green turtles having higher basal levels of corticosterone and producing significantly more corticosterone in response to capture stress than non-breeding adult turtles. In contrast there was no significant sex difference in the corticosterone stress response of green turtles irrespective of age class. In summary, green turtles exhibited an adrenocortical response to a capture stress protocol. This response was significantly associated with different age classes, perhaps suggesting that the response is increased in juvenile turtles to offset the reduced probability of survival consistent with this more vulnerable age class.
Breeding ecology of the rainforest dung beetle Cephalodesmius armiger (Scarabaeidae) in Tooloom National Park
Authors: Dalgleish Elizabeth A. , Elgar Mark A.
Published: April 2005

The ecology of the rainforest dung beetle Cephalodesmius armiger was investigated in Tooloom National Park, within the high-altitude rainforest of north-east New South Wales. We observed considerable overlap in the brood-rearing stages of the breeding cycle. The operational sex ratio was female-biased. Biparental care is provided in this species, but it is not obligatory; females reared one brood either in partnership with a male or alone, and males did or did not pair with a female and rear a brood. There was spatial variation in the density of burrows. The availability of brood-burrows for brood rearing appears to be limited and evidence of the recycling of brood-burrows was collected for the first time. We suggest that the temporal variation in the breeding cycle arises from individual variation in the development and degeneration of the reproductive organs, rather than ecological factors favouring burrow and larder preparation. The female-biased operation sex ratio may result in males being more selective in their choice of mates than females and less committed to brood rearing.
Population density and presence of the mother are related to natal dispersal in male and female Antechinus stuartii
Authors: Fisher D. O.
Published: April 2005

In common with most mammals, the frequency of natal dispersal in antechinuses is strongly male-biased. Inbreeding avoidance has been put forward as the most likely explanation, with juvenile dispersal being driven by the mother. Dispersal distances and factors affecting emigration and immigration of each sex have not previously been studied in antechinuses, because of the difficulty of following the fates of individual dispersers. I studied a dense population of brown antechinuses (Antechinus stuartii) of known parentage in linear habitat that could be comprehensively trapped, and determined the fate of 27 females and 14 males that survived to dispersal age. Juvenile males dispersed not only more frequently than females (71% v. 11%), but also much further (maximum known distance: 1230 m v. 270 m). Males dispersed further if they had been raised in an area of low population density, and were more likely to immigrate into an area with a higher density of females than the natal site. Death of the mother disrupted normal home-range establishment, resulting in frequent philopatry of sons and dispersal of some daughters. Some females emigrated after young were weaned, and this also prompted dispersal of daughters. There was no evidence that daughters with surviving, philopatric mothers were more likely to survive to breed. I conclude that male-biased dispersal appears to result not only from costs of inbreeding, but also partly by the benefits of finding a site with more mating opportunities.
Identification of the control region for tissue-specific imprinting of the stimulatory G protein α-subunit
Authors: Liu Jie , Chen Min , Deng Chuxia , Bourc'his Déborah , Nealon Julie G. , Erlichman Beth , Bestor Timothy H. , Weinstein Lee S.
Published: April 2005

Gnas
is a complex gene with multiple imprinted promoters. The upstream
Nesp
and
Nespas
/
Gnasxl
promoters are paternally and maternally methylated, respectively. The downstream promoter for the stimulatory G protein α-subunit (G
s
α) is unmethylated, although in some tissues (e.g., renal proximal tubules), G
s
α is poorly expressed from the paternal allele. Just upstream of the G
s
α promoter is a primary imprint mark (1A region) where maternal-specific methylation is established during oogenesis. Pseudohypoparathyroidism type 1B, a disorder of renal parathyroid hormone resistance, is associated with loss of 1A methylation. Analysis of embryos of
Dnmt3L
–/–
mothers (which cannot methylate maternal imprint marks) showed that
Nesp
,
Nespas
/
Gnasxl
, and 1A imprinting depend on one or more maternal primary imprint marks. We generated mice with deletion of the 1A differentially methylated region. These mice had normal
Nesp-Nespas
/
Gnasxl
imprinting, indicating that the
Gnas
locus contains two independent imprinting domains (
Nespas-Nespas
/
Gnasxl
and 1A-G
s
α) controlled by distinct maternal primary imprint marks. Paternal, but not maternal, 1A deletion resulted in G
s
α overexpression in proximal tubules and evidence for increased parathyroid hormone sensitivity but had no effect on G
s
α expression in other tissues where G
s
α is normally not imprinted. The 1A region is a maternal imprint mark that contains one or more methylation-sensitive cis-acting elements that suppress G
s
α expression from the paternal allele in a tissue-specific manner.
Impact of distal mutations on the network of coupled motions correlated to hydride transfer in dihydrofolate reductase
Authors: Wong Kim F. , Selzer Tzvia , Benkovic Stephen J. , Hammes-Schiffer Sharon
Published: April 2005

A comprehensive analysis of the network of coupled motions correlated to hydride transfer in dihydrofolate reductase is presented. Hybrid quantum/classical molecular dynamics simulations are combined with a rank correlation analysis method to extract thermally averaged properties that vary along the collective reaction coordinate according to a prescribed target model. Coupled motions correlated to hydride transfer are identified throughout the enzyme. Calculations for wild-type dihydrofolate reductase and a triple mutant, along with the associated single and double mutants, indicate that each enzyme system samples a unique distribution of coupled motions correlated to hydride transfer. These coupled motions provide an explanation for the experimentally measured nonadditivity effects in the hydride transfer rates for these mutants. This analysis illustrates that mutations distal to the active site can introduce nonlocal structural perturbations and significantly impact the catalytic rate by altering the conformational motions of the entire enzyme and the probability of sampling conformations conducive to the catalyzed reaction.
Directed evolution of specific receptor–ligand pairs for use in the creation of gene switches
Authors: Chockalingam Karuppiah , Chen Zhilei , Katzenellenbogen John A. , Zhao Huimin
Published: April 2005

Despite their versatility and power in controlling gene regulation in nature, nuclear hormone receptors (NHRs) have largely eluded utility in heterologous gene regulation applications such as gene therapy and metabolic engineering. The main reason for this void is the pleiotropic interference of the receptor–ligand combination with regulatory networks in the host organism. In recent years, numerous strategies have been developed to engineer ligand–receptor pairs that do not cross-interact with host regulatory pathways. However, these strategies have either met with limited success or cannot be readily extended to other ligand–receptor pairs. Here, we present a simple, effective, and readily generalizable strategy for reengineering NHRs to respond specifically to a selected synthetic ligand. The method involves generation of genetic diversity by stepwise individual site saturation mutagenesis of a fixed set of ligand-contacting residues and random point mutagenesis, followed by phenotypic screening based on a yeast two-hybrid system. As a test case, this method was used to alter the specificity of the NHR human estrogen receptor α in favor of the synthetic ligand 4,4′-dihydroxybenzil, relative to the natural ligand 17β-estradiol, by >107-fold. The resulting ligand–receptor pair is highly sensitive to the synthetic ligand in human endometrial cancer cells and is essentially fully orthogonal to the wild-type receptor–natural ligand pair. This method should provide a powerful, broadly applicable tool for engineering receptors/enzymes with improved or novel ligand/substrate specificity.
Who owns scientific data? The impact of intellectual property rights on the scientific publication chain
Authors: Elliott Roger
Published: April 2005

Intellectual property rights have become increasingly important in scientific research. As the legal regime has been tightened and attitudes of funders, employers and researchers have changed, serious challenges are emerging to the free flow of ideas and information on which the scientific enterprise rests. It is important that individual scientists are aware of their rights and convinced to use them in the public good.
Serving science while paying the bills: the history of the Journal of Biological Chemistry Online
Authors: Simoni Robert D.
Published: April 2005

Recent developments in the publication of the Journal of Biological Chemistry (JBC) are discussed, particularly the development of the electronic version of the Journal, JBC Online, and the opportunities and challenges that this mode of publication has presented to its publisher, the American Society for Biochemistry and Molecular Biology (ASBMB) and its mission of service.
The ATP-dependent Membrane Localization of Protein Kinase Cα Is Regulated by Ca2+ Influx and Phosphatidylinositol 4,5-Bisphosphate in Differentiated PC12 Cells
Authors: Marín-Vicente Consuelo , Gómez-Fernández Juan C. , Corbalán-García Senena
Published: April 2005

Signal transduction through protein kinase Cs (PKCs) strongly depends on their subcellular localization. Here, we investigate the molecular determinants of PKCα localization by using a model system of neural growth factor (NGF)-differentiated pheochromocytoma (PC12) cells and extracellular stimulation with ATP. Strikingly, the Ca2+ influx, initiated by the ATP stimulation of P2X receptors, rather than the Ca2+ released from the intracellular stores, was the driving force behind the translocation of PKCα to the plasma membrane. Furthermore, the localization process depended on two regions of the C2 domain: the Ca2+-binding region and the lysine-rich cluster, which bind Ca2+ and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], respectively. It was demonstrated that diacylglycerol was not involved in the localization of PKCα through its C1 domain, and in lieu, the presence of PtdIns(4,5)P2 increased the permanence of PKCα in the plasma membrane. Finally, it also was shown that ATP cooperated with NGF during the differentiation process of PC12 cells by increasing the length of the neurites, an effect that was inhibited when the cells were incubated in the presence of a specific inhibitor of PKCα, suggesting a possible role for this isoenzyme in the neural differentiation process. Overall, these results show a novel mechanism of PKCα activation in differentiated PC12 cells, where Ca2+ influx, together with the endogenous PtdIns(4,5)P2, anchor PKCα to the plasma membrane through two distinct motifs of its C2 domain, leading to enzyme activation.
A nonlinear, anisotropic and axisymmetric model for balloon angioplasty
Authors: Eftaxiopoulos Dimitrios A , Atkinson Colin
Published: April 2005

A nonlinear elastic, anisotropic and axisymmetric balloon angioplasty model, consisting of the balloon, the atherosclerotic plaque and the artery wall, has been developed and analysed in this paper. The deformation of the angioplasty compound, i.e. the balloon, the plaque and the artery, for slowly increasing dilation pressure within the balloon, is investigated. The plaque has been considered as a circular cylindrical tube extending all around the artery circumference. Normal radial stress and radial displacement boundary conditions have been imposed along the balloon–plaque and the plaque–artery interfaces. Large elastic deformations have been accommodated in the model. The balloon material has been considered as isotropic, the plaque material as transversely isotropic and the artery wall material as orthotropic. A strain energy density function, that satisfies existing incomplete experimental data, has been constructed for the plaque material. For a given dilation pressure within the balloon, the deformation of the angioplasty compound is determined via the numerical solution of a system of four nonlinear equations. For a medium hard balloon and a medium stiff plaque, a dilation pressure 7.5 times bigger than the blood pressure is required for an almost full reopening of the narrowed lumen. The percentage increase in length of the inner radius of the plaque is twice bigger than that of the radius of the artery. Results also indicate that the process of full reopening may be achievable, without stressing the artery wall dramatically.
Winter availability of cereal stubbles attracts declining farmland birds and positively influences breeding population trends
Authors: Gillings Simon , Newson Stuart E , Noble David G , Vickery Juliet A
Published: April 2005

Many studies have demonstrated the selection of stubble fields by farmland birds in winter, but none have shown whether provisioning of this key habitat positively influences national population trends for widespread farmland birds. We use two complementary extensive bird surveys undertaken at the same localities in summer and winter and show that the area of stubble in winter attracts increased numbers of several bird species of conservation concern. Moreover, for several farmland specialists, the availability of stubble fields in winter positively influenced the 10 year breeding population trend (1994–2003) whereas hedgerow bird species were less affected. For skylarks and yellowhammers, initially negative trends showed recovery with 10–20 ha of stubble per 1 km square. Thus, agri-environment schemes that promote retention of over-winter stubbles will attract birds locally and are capable of reversing current population declines if stubbles are available in sufficient quantity.
Directionality theory: a computational study of an entropic principle in evolutionary processes
Authors: Kowald Axel , Demetrius Lloyd
Published: April 2005

Analytical studies of evolutionary processes based on the demographic parameter entropy—a measure of the uncertainty in the age of the mother of a randomly chosen newborn—show that evolutionary changes in entropy are contingent on environmental constraints and can be characterized in terms of three tenets: (i) a unidirectional increase in entropy for populations subject to bounded growth constraints; (ii) a unidirectional decrease in entropy for large populations subject to unbounded growth constraints; (iii) random, non-directional change in entropy for small populations subject to unbounded growth constraints. This article aims to assess the robustness of these analytical tenets by computer simulation. The results of the computational study are shown to be consistent with the analytical predictions. Computational analysis, together with complementary empirical studies of evolutionary changes in entropy underscore the universality of the entropic principle as a model of the evolutionary process.
Directionally compliant legs influence the intrinsic pitch behaviour of a trotting quadruped
Authors: Lee David V , Meek Sanford G
Published: April 2005

Limb design is well conserved among quadrupeds, notably, the knees point forward (i.e. cranial inclination of femora) and the elbows point back (i.e. caudal inclination of humeri). This study was undertaken to examine the effects of joint orientation on individual leg forces and centre of mass dynamics. Steady-speed trotting was simulated in two quadrupedal models. Model I had the knee and elbow orientation of a quadruped and model II had a reversed leg configuration in which knees point back and elbows point forward. The model's legs showed directional compliance determined by the orientation of the knee/elbow. In both models, forward pointing knees/elbows produced a propulsive force bias, while rearward pointing knees/elbows produced a braking force bias. Hence, model I showed the same pattern of hind-leg propulsion and fore-leg braking observed in trotting animals. Simulations revealed minimal pitch oscillations during steady-speed trotting of model I, but substantially greater and more irregular pitch oscillations of model II. The reduced pitch oscillation of model I was a result of fore-leg and hind-leg forces that reduced pitching moments during early and late stance, respectively. This passive mechanism for reducing pitch oscillations was an emergent property of directionally compliant legs with the fore–hind configuration of model I. Such intrinsic stability resulting from mechanical design can simplify control tasks and lead to more robust running machines.
Ambient noise and the design of begging signals
Authors: Leonard Marty L , Horn Andrew G
Published: April 2005

The apparent extravagance of begging displays is usually attributed to selection for features, such as loud calls, that make the signal costly and hence reliable. An alternative explanation, however, is that these design features are needed for effective signal transmission and reception. Here, we test the latter hypothesis by examining how the begging calls of tree swallow (
Tachycineta bicolor
) nestlings and the response to these calls by parents are affected by ambient noise. In a field study, we found that call length, amplitude and frequency range all increased with increasing noise levels at nests. In the laboratory, however, only call amplitude increased in response to the playback of noise to nestlings. In field playbacks to parents, similar levels of noise abolished parental preferences for higher call rates, but the preference was restored when call amplitude was increased to the level that nestlings had used in the laboratory study. Our results show that nestling birds, like other acoustic signallers, consistently increase call amplitude in response to ambient noise and this response appears to enhance discrimination by receivers. Thus, selection for signal efficacy may explain some of the seemingly extravagant features of begging displays.
MHC-based patterns of social and extra-pair mate choice in the Seychelles warbler
Authors: Richardson David S , Komdeur Jan , Burke Terry , von Schantz Torbjörn
Published: April 2005

The existence and nature of indirect genetic benefits to mate choice remain contentious. Major histocompatibility complex (MHC) genes, which play a vital role in determining pathogen resistance in vertebrates, may be the link between mate choice and the genetic inheritance of vigour in offspring. Studies have shown that MHC-dependent mate choice can occur in mammal and fish species, but little work has focused on the role of the MHC in birds. We tested for MHC-dependent mating patterns in the Seychelles warbler (
Acrocephalus sechellensis
). There was no influence of MHC class I exon 3 variation on the choice of social mate. However, females were more likely to obtain extra-pair paternity (EPP) when their social mate had low MHC diversity, and the MHC diversity of the extra-pair male was significantly higher than that of the cuckolded male. There was no evidence that females were mating disassortatively, or that they preferred males with an intermediate number of MHC bands. Overall, the results are consistent with the ‘good genes’ rather than the ‘genetic compatibility’ hypothesis. As female choice will result in offspring of higher MHC diversity, MHC-dependent EPP may provide indirect benefits in the Seychelles warbler if survival is positively linked to MHC diversity.
Small‐scale distribution of juvenile plaice and flounder in relation to predatory shrimp in a shallow Swedish bay
Authors: Modin J. , Pihl L.
Published: April 2005

Metamorphosed plaice and flounder were sampled in a small non‐tidal nursery bay with a non‐selective drop trap from April to August in 1991 and 1992. Post‐settlement patterns were mapped in time and space and related to wind stress and the distribution of a potential predator Crangon crangon L. Both plaice and flounder had a patchy distribution at a sample scale of 1 m2. Plaice settlement coincided with timing of onshore winds in 1991 and 1992, while flounder settlement seemed to be unrelated. Plaice settled earlier than flounder and during the early phase of 1‐group C. crangon immigration. The first appearance of flounder occurred simultaneously with the peak biomass of predatory C. crangon. Plaice occurred in the deeper part of the bay together with C. crangon, while flounder preferred shallow shore waters. We propose that different temporal (plaice) and spatial (flounder) strategies have evolved in order to minimize the risk of shrimp predation after settlement.
Allozymic variation and relationships of the endangered cyprinodontid genus Valencia and its implications for conservation
Authors: Perdices A. , Machordom A. , Doadrio I.
Published: April 2005

Allozyme analysis was used to determine patterns of genetic variation and relationships within the genus Valencia, a group with two allopatric species, V. letourneuxi inhabiting the Balkan Peninsula, and V. hispanica which is endemic to the Iberian Peninsula. Products of 25 gene loci were analysed with AK*, FH*, LDH‐1* and LDH‐2* monomorphic when Fundulus heteroclitus macrolepidotus was not taken into account. Nine loci were diagnostic for both species of the genus Valencia. Levels of genetic variation of V. hispanica (P=0·416, He=0·118) and V. letourneuxi (P=0·160, He=0·040) were higher than values reported previously. High population subdivision (Fst=0·321) among V. hispanica populations indicates a clear interruption of genetic exchange among populations. High genetic variation and differentiation exhibited by populations of V. hispanica suggest that a recovery program should be carried out with natural stocks from the same localities.
Diel locomotor activity of brook charr, as determined by radiotelemetry
Authors: Bourke P. , Magnan P. , Rodríguez M. A.
Published: April 2005

Locations by radiotelemetry during eight 24–h sampling periods in 1991, 1992, and 1993 were used to evaluate the diel activity patterns of adult brook charr Salvelinus fontinalis in two lakes of the Laurentian Shield (Québec, Canada). Based on the minimum distance travelled between two consecutive locations, adult brook charr were more active at dusk and at night than during the day. During daylight periods, individual fish displayed strong site selection, remaining in the same area along the shore from day to day. The fish left their inshore position at dusk, were highly mobile during the night, and returned to their focal point at sunrise, exhibiting diel homing behaviour. These results are supported by an increase in gillnet captures of adult brook charr in Lac Melchior at night. Data obtained by gillnet fishing in lakes Bondi and Simpson showed that juvenile (1+) brook charr were active throughout the diel cycle and that young‐of‐the‐year were active mainly during the day, suggesting that there is an ontogenetic change in the diel activity of brook charr. Despite its limitations (restrictions on the number and size of tracked individuals, post‐manipulation mortality, lifetime of transmitter battery), radiotelemetry allows for collection of multiple behavioural observations (distances travelled, instantaneous activity, site selection and homing) during the activity cycle of individual fish, and thus provides a finer degree of spatial resolution than alternative methods such as gillnetting.
Distribution and reproduction of the southern lantern shark from New Zealand
Authors: Wetherbee B. M.
Published: April 2005

Distribution, population structure and reproduction are described for the southern lantern shark Etmopterus granulosus at the Chatham Rise, New Zealand. Depth of capture for E. granulosus ranged from 744 to 1420 m, with highest catch rates between 800–1200 m. More than twice as many females as males were captured, and the majority of sharks caught were mature, indicating that there may be segregation according to sex and size class. Only 10 of 492 female sharks captured contained ova in uteri, and none contained embryos. The absence of pregnant females suggests that they move to another area or depth prior to pupping. Size of sharks captured ranged from 20·0 to 78·8 cm total length. Females began to mature at 62 cm total length, and males at 52 cm. There was no evidence of a seasonal reproductive cycle. Ovulation appeared to occur when ova reached a diameter of 40–45 mm. The average number of ova in mature females was 12·7. This information is crucial for assessing the impact of fisheries on E. granulosus populations.
Oocyte size and structure in relation to blood plasma steroid hormones in individually monitored, spawning Atlantic cod
Authors: Kjesbu O. S. , Kryvi H. , Norberg B.
Published: April 2005

A series of seasonal blood and ovarian tissue samples were taken from five female Atlantic cod Gadus morhua at different times between various batches of eggs and subsequently examined for oocyte size, plasma steroid hormones and ultrastructure of the cortex oocyte cytoplasm and follicle layer. This detailed protocol demonstrated that the spawning cod ovary is vitellogenically very active. Individual oocytes were able to develop at different rates, and at least two cohorts of oocytes with a different developmental status were present simultaneously. The concentration of estradiol‐17β varied between batches and decreased over the season. The levels of 17,20β‐P and 11‐deoxycortisol were generally low. Oocytes of an advanced developing cohort showed numerous coated vesicles and closely apposed oocytic and follicular microvilli located in the chorionic pores. The number of oocytic microvilli was estimated at about 1–8 million cell−1, which increased the oocyte surface area by a factor of 12. Furthermore, the oocytic microvilli were found to stretch during final maturation. This stage‐specific mobility of microvilli is discussed in relation to further incorporation of yolk and the relevant actin‐based cytoskeleton observed for other classes of animals.
Stable isotopes of carbon and nitrogen as indicators of diet and trophic structure of the fish community in a shallow hypereutrophic lake
Authors: Gu B. , Schelske C. L. , Hoyer M. V.
Published: April 2005

Stable carbon (δ13C) and nitrogen (δ15N) isotopes were employed to elucidate energy flows and trophic interactions in Lake Apopka, a hypereutrophic lake in central Florida, U.S.A. Isotope compositions of lake biota ranged from −27·1 to −3·0‰ for δ13C, and from 3·7 to 13·9‰ for δ15N. The food web was based primarily on plankton production with diatoms, Microcystis and zooplankton dominating the diet of fish. Carbon isotope evidence showed that pico‐ and nano‐phytoplankton were not a direct carbon source for fish, but were important to zooplankton. δ15N mass balance estimates indicated that planktivorous fish obtained 48–85% of their diets from zooplankton. The ∼3‰ range of δ15N in gizzard shad reflected increasing dependence on zooplankton as fish grew whereas the positive relationship between total length and δ15N of largemouth bass reflected increasing predation on larger planktivorous fish with growth. The broad ranges of δ13C (−25·9 to −9·5‰) and δ15N (5·8 to 14·4‰) of blue tilapia were indicators of diet diversity. Two presumed omnivores (brown bullhead and white catfish) and piscivores (black crappie, largemouth bass and Florida gar) were found to depend on planktivorous fish. However, stable isotope data revealed no trophic links between blue tilapia, an abundant fish in the near‐shore area, and piscivores.
Protein differences among the Mediterranean species of the genus Spicara
Authors: Arculeo M. , Mauro A. , Scelsa G. , Lo Brutto S. , Cammarata M. , Parrinello N.
Published: April 2005

Protein electrophoresis (PAGE) was used to study the three morphologically different species of Spicara (S. flexuosa, S. maena, S. smaris). Of the 28 enzymatic and additional myogenic loci, five monomorphic loci (LDH‐1*, G6PD‐1*, PGI‐1* and two PMMs*) were species‐specific markers of S. smaris with respect to S. flexuosa and S. maena. Four of the 28 enzymatic loci were polymorphic (EST‐1*, GLDH*, PEPD*, PGI‐2*). Discriminating genetic markers were not identified between S. flexuosa and S. maena. Genetic distance (D) as calculated by Nei's index (1978), between S. smaris v. S. maena and S. flexuosa showed a value, respectively of Z) = 0·137 and 0·141. Between S. flexuosa and S. maena the value was Z)=0‐006. From the data it can be inferred that S. flexuosa and S. maena are conspecific, despite morphological differences.
Predation of doggertooth on immature Pacific salmon
Authors: Radchenko V. I. , Yu. Semenchenko A.
Published: April 2005

First occurrence of doggertooth predation on immature Pacific salmon is described from the Okhotsk Sea, off the Northern Kurile Islands. The possible significance of doggertooth for salmon abundance is discussed.
Conservation of microsatellites in three species of salmonids
Authors: Presa P. , Guyomard R.
Published: April 2005

The conservation of flanking regions of ten microsatellites has been investigated in three salmonid species. The proportion of conserved microsatellites and the level of polymorphism are high in the three species. This confirms the potential interest of microsatellite loci for interspecific comparisons.
Effect of AC electroshock on blood features in juvenile rainbow trout
Authors: Barton B. A. , Grosh R. S.
Published: April 2005

Brief AC electroshock caused significant elevations in plasma cortisol, glucose, osmolality, and chloride levels in rainbow trout within 15min, but plasma protein was reduced at 3h. Circulating granulocytes had declined by 15min, but other haematological features remained unchanged. Thus, AC electrofishing would not be suitable for monitoring physiological conditions in trout if short delays are encountered before blood is sampled.
Hodgkin's disease variant of Richter's syndrome in chronic lymphocytic leukaemia patients previously treated with fludarabine
Authors: Fong Dominic , Kaiser Alexandra , Spizzo Gilbert , Gastl Guenther , Tzankov Alexandar
Published: April 2005

The transformation of chronic lymphocytic leukaemia (CLL) into large‐cell lymphoma (Richter's syndrome, RS) is a well‐documented phenomenon. Only rarely does CLL transform into Hodgkin's lymphoma (HL). To further analyse the clinico‐pathological and genetic findings in the HL variant of RS, we performed a single‐institution study in four patients, who developed HL within a mean of 107 months after diagnosis of CLL. All were treated with fludarabine. Three cases were Epstein–Barr virus (EBV)‐associated mixed cellularity (MC) HL, the fourth was nodular sclerosis (NS) HL without EBV association. The sites involved by HL included supra‐ and infradiaphragmal lymph nodes and the tonsils; stage IV disease was also documented. All patients presented with CLL treatment‐resistant lymphadenopathies and B‐symptoms. In two of the MC cases, molecular analysis performed on CLL samples and microdissected Hodgkin and Reed–Sternberg cells (HRSC) suggested a clonal relationship, while in NS no indication of a clonal relationship was detected. In summary, HL can occur in CLL patients at any site, up to 17 years after initial diagnosis, especially after treatment with fludarabine. The majority present with B‐symptoms and CLL treatment‐resistant lymphadenopathy, are of the MC type, clonally related to CLL and might be triggered by an EBV infection.
Increased incidence of EBV‐related disease following paediatric stem cell transplantation with reduced‐intensity conditioning
Authors: Cohen Jonathan , Gandhi Minal , Naik Paru , Cubitt David , Rao Kanchan , Thaker Urvashi , Graham Davies E. , Bobby Gaspar H. , Amrolia Persis J. , Veys Paul
Published: April 2005

The incidence of Epstein–Barr virus (EBV) viraemia and lymphoproliferative disease (LPD) was studied in a consecutive cohort of 128 paediatric patients undergoing stem cell transplantation (SCT) with reduced‐intensity conditioning (RIC; n = 65) or conventional‐intensity conditioning (CIC; n = 68). Following CIC, six of 68 (8%) developed viraemia; all remained asymptomatic. EBV viraemia (23 of 65 patients = 35%, P < 0·001) and LPD (10 of 65 = 15%, P < 0·001) were significantly more frequent following RIC. Of the 23 RIC patients who developed viraemia, eight remained asymptomatic, five had symptomatic viraemia (fever ± rash), and 10 patients developed LPD, two of whom died. An absolute lymphocyte count of <0·3 × 109/l at the time of onset of viraemia was strongly predictive of development of LPD (P < 0·05) in this group. The incidence of viraemia was significantly higher in patients receiving serotherapy with antithymocyte globulin (ATG; 15 of 43, 35%) than Campath (12 of 73, 16·4%, P < 0·05). Primary immunodeficiency and acute graft‐versus‐host disease were associated with EBV viraemia in univariate analysis, but were not independent risk factors. In conclusion, EBV viraemia and LPD appear to be significantly more common in children following RIC SCT, particularly with selective depletion of recipient T cells relative to B cells following the use of ATG. This probably reflects the profound immunosuppression following RIC SCT, together with the incomplete ablation of recipient‐derived B cells.
Impact of epoetin‐β on survival of patients with lymphoproliferative malignancies: long‐term follow up of a large randomized study*
Authors: Österborg Anders , Brandberg Yvonne , Hedenus Michael
Published: April 2005

Recent studies have suggested that epoetin treatment of anaemia may influence the survival of patients with cancer. We conducted an analysis of long‐term survival in patients with lymphoproliferative malignancies treated with epoetin‐β or placebo in a large‐scale study. This was a randomized, double‐blind trial in which patients with transfusion‐dependent anaemia and lymphoproliferative malignancy received epoetin‐β 150 IU/kg or placebo three times weekly for 16 weeks. Long‐term survival data were analysed by standard Kaplan–Meier methods and differences between groups were assessed using a log‐rank test. The intention‐to‐treat population consisted of 343 patients (epoetin‐β, n = 170; placebo, n = 173). There were no major differences between the two treatment groups in demographic or clinical characteristics/prognostic factors. A total of 110 (65%) patients died in the epoetin‐β group (censored, n = 60) and 109 (63%) died in the placebo group (censored, n = 64) up to the end of long‐term follow up. Kaplan–Meier curves for survival were similar in both groups. Median survival was 17 months with epoetin‐β and 18 months with placebo. A log‐rank test indicated no significant difference in survival (P = 0·76). This long‐term follow up indicated that epoetin‐β has no significant effect on survival compared to placebo in anaemic patients with lymphoproliferative malignancies.
Del (9q) AML: clinical and cytological characteristics and prognostic implications
Authors: Peniket Andrew , Wainscoat James , Side Lucy , Daly Sarah , Kusec Rajko , Buck Georgina , Wheatley Keith , Walker Helen , Chatters Steve , Harrison Christine , Boultwood Jacqueline , Goldstone Anthony , Burnett Alan
Published: April 2005

Del (9q) is a recurrent cytogenetic abnormality in acute myeloid leukaemia (AML). We report an analysis of 81 patients with del(9q) as a diagnostic karyotypic abnormality entered into the Medical Research Council AML trials 10, 11 and 12. Patients were divided into three groups: (i) Sole del (9q), 21 patients; (ii) Del(9q) in association with t(8;21), 29 patients; (iii) Del(9q) in association with other cytogenetic abnormalities, 31 patients. Sole del(9q) was associated with a characteristic bone marrow phenotype at diagnosis: a single Auer rod was found in all cases examined. There was also an association with erythroid dysplasia (74%) and granylocytic lineage vacuolation (90%). The incidence of all three of these features was significantly higher (P < 0·05) in the sole del(9q) group compared with control cases lacking del(9q). The overall survival (OS) of all 81 patients was compared with a control group of 1738 patients with normal cytogenetics entered in the same trials over the period of investigation. The 5‐year OS for patients with del(9q) was 45%, compared with 35% for the control group (P = 0·09). Patients with del(9q) in association with t(8;21) had a 5‐year OS of 75%, which was significantly better than the groups with either sole del(9q) (40%) and del(9q) with other abnormalities (26%; P = 0·008). Karyotyping indicated a common area of deletion in the region 9q21–22, which was present in 94% of cases. It is likely that the deletion of single or multiple tumour suppressor genes located in this region may underlie the pathogenesis of del (9q) AML.