bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal dynamics and spatial variability in the enhancement of canopy leaf area under elevated atmospheric CO2
Authors: McCARTHY HEATHER R. , OREN RAM , FINZI ADRIEN C. , ELLSWORTH DAVID S. , KIM HYUN‐SEOK , JOHNSEN KURT H. , MILLAR BONNIE
Published: October 2007

Increased canopy leaf area (L) may lead to higher forest productivity and alter processes such as species dynamics and ecosystem mass and energy fluxes. Few CO2enrichment studies have been conducted in closed canopy forests and none have shown a sustained enhancement ofL. We reconstructed 8 years (1996–2003) ofLat Duke's Free Air CO2Enrichment experiment to determine the effects of elevated atmospheric CO2concentration ([CO2]) onLbefore and after canopy closure in a pine forest with a hardwood component, focusing on interactions withtemporalvariation in water availability andspatialvariation in nitrogen (N) supply. The dynamics ofLwere reconstructed using data on leaf litterfall mass and specific leaf area for hardwoods, and needle litterfall mass and specific leaf area combined with needle elongation rates, and fascicle and shoot counts for pines. The dynamics of pineLproduction and senescence were unaffected by elevated [CO2], althoughLsenescence for hardwoods was slowed. Elevated [CO2] enhanced pineLand the total canopyL(combined pine and hardwood species;P<0.050); on average, enhancement following canopy closure was ∼16% and 14% respectively. However, variation in pineLand its response to elevated [CO2] was not random. Each year pineLunder ambient and elevated [CO2] wasspatiallycorrelated to the variability in site nitrogen availability (e.g.r2=0.94 and 0.87 in 2001, whenLwas highest before declining due to droughts and storms), with the [CO2]‐induced enhancement increasing with N (P=0.061). Incorporating data on N beyond the range of native fertility, achieved through N fertilization, indicated that pineLhad reached the site maximum under elevated [CO2] where native N was highest. Thus closed canopy pine forests may be able to increase leaf area under elevated [CO2] in moderate fertility sites, but are unable to respond to [CO2] in both infertile sites (insufficient resources) and sites having high levels of fertility (maximum utilization of resources). The total canopyL, representing the combinedLof pine and hardwood species, was constant across the N gradient under both ambient and elevated [CO2], generating a constant enhancement of canopyL. Thus, in mixed species stands,Lof canopy hardwoods which developed on lower fertility sites (∼3 g N inputs m−2 yr−1) may be sufficiently enhanced under elevated [CO2] to compensate for the lack of response in pineL, and generate an appreciable response of total canopyL(∼14%).
Immune tolerance therapy utilizing factor VIII/von Willebrand factor concentrate in haemophilia A patients with high titre factor VIII inhibitors
Authors: KURTH M. A. H. , DIMICHELE D. , SEXAUER C. , SANDERS J. M. , TORRES M. , ZAPPA S. C. , RAGNI M. , LEONARD N.
Published: October 2007

Summary.  Factor VIII (FVIII) inhibitors remain a serious complication of treatment for patients with haemophilia A. Immune tolerance induction (ITI) can eliminate inhibitors in the majority of patients, but there are major concerns related with this therapy. Investigators have raised the possibility that the use of FVIII/von Willebrand factor (FVIII/VWF) concentrates may improve the success rate of ITI and may shorten the duration of therapy necessary to attain tolerance. This retrospective study describes 25 patients at five institutions in the USA, who were treated with FVIII/VWF concentrate as part of their ITI. These were all patients who were considered poor prognosis because of clinical and laboratory characteristics, which made ITI less likely to be successful or because of a poor response to initial ITI with a monoclonal/recombinant FVIII concentrate. Overall success (complete tolerization) was 32% with another 40% attaining partial tolerization, but not complete tolerization. Of those patients attaining only partial tolerization, two patients ultimately discontinued ITI and had return of their high titre inhibitors. Eight percent of patients failed to attain either partial or complete tolerization and discontinued ITI. Another 24% are continuing with ITI but have titres of >10 BU. This study adds further retrospective data to the information regarding the use of FVIII/VWF concentrate in ITI.
Pregnancy in carriers of haemophilia
Authors: CHI C. , LEE C. A. , SHILTAGH N. , KHAN A. , POLLARD D. , KADIR R. A.
Published: October 2007

Summary.  The aim of the study was to review the complications, management and outcome of pregnancy in carriers of haemophilia over a 10‐year period following the introduction of a multidisciplinary management guideline. Comparison was made to a 10‐year cohort prior to implementation of the guidelines. A retrospective review of case notes of carriers of haemophilia (41 haemophilia A, 12 haemophilia B) who had received obstetric care at the Royal Free Hospital between 1995 and 2005 was conducted. There were 90 pregnancies (65 live births, 13 miscarriages, 12 terminations). Prenatal testing was taken up in 97% (63/65) of pregnancies where the mother was known to be a carrier of haemophilia. The majority (71%; 46/65) chose only to have non‐invasive fetal sex determination. Seventeen (26%) had invasive testing (13 primarily for haemophilia and four primarily for chromosomal abnormalities). Termination of pregnancy was opted for in 67% (6/9) of pregnancies affected with haemophilia. Pregnancy was accompanied by a marked rise in factor VIII levels compared to only a small rise in factor IX levels. Invasive intrapartum monitoring techniques and instrumental deliveries were avoided in all pregnancies known to be at risk of haemophilia. Regional block was performed in 25 pregnancies for labour/delivery with no complications. The caesarean section rate was 47%. The incidence of primary and secondary postpartum haemorrhage was 19% and 2%, respectively. There were two neonatal head bleeding complications associated with prolonged labour or instrumental delivery. Availability of management guideline and care provided in a multidisciplinary approach can help to minimize bleeding complications in carriers of haemophilia and their newborns.
Plasmablastic lymphomas may occur as post‐transplant lymphoproliferative disorders
Authors: Borenstein J , Pezzella F , Gatter K C
Published: October 2007

Aims:  To describe four cases of plasmablastic lymphoma arising in the unusual setting of a post‐transplantation lymphoproliferative disorder (PTLD).

Methods and results:  Four cases were encountered over 2 years in human immunodeficiency virus (HIV)‐negative patients following renal, heart or bone marrow transplantation. The cases were routinely processed and immunohistochemistry was performed. The cases showed blastic non‐Hodgkin’s lymphoma morphology and plasma cell‐like immunophenotypic features: minimal or absent expression of leucocyte common antigen and CD20, variable CD79a and VS38 positivity. Monoclonal light chain restriction was also detected.

Conclusions:  The emphasis of this paper is to document further the occurrence of plasmablastic lymphomas in HIV− individuals and to expand the spectrum of PTLD.
Immunotherapeutic potential of the immunodominant T‐cell epitope of lipocalin allergen Bos d 2 and its analogues
Authors: Saarelainen Soili A. , Kinnunen Tuure T. , Buhot Cécile , Närvänen Ale T. O. , Kauppinen Anu K. , Rytkönen‐Nissinen Marja A. , Maillere Bernard , Virtanen Tuomas I.
Published: October 2007

Lipocalin allergens, which contain most of the important animal‐derived respiratory sensitizers, induce T helper type 2 (Th2) deviation, but the reasons for this are not clear. To explore the prospects for peptide‐based allergen immunotherapy and to elucidate the characteristics of the immunodominant epitope of Bos d 2, BALB/c mice were immunized with a peptide containing the epitope, peptides containing its analogues, peptides from the corresponding regions of other lipocalin proteins, and peptides with a homologous sequence. We observed that murine spleen cells recognized the immunodominant epitope of Bos d 2, p127–142, in almost the same way as human Bos d 2‐specific T cells did. Enzyme‐linked immunosorbent spot‐forming cell assay (ELISPOT) analyses showed that p127–142 and a corresponding peptide from horse Equ c 1 induced a Th2‐deviated cellular response, whereas a homologous bacterial peptide from Spiroplasma citri induced a Th0‐type response. Interestingly, the spleen cell response to the bacterial peptide and p127–142 was cross‐reactive, that is, able to induce reciprocally the proliferation and cytokine production of primed spleen cells in vitro. More importantly, the peptides were able to skew the phenotype of T cells primed with the other peptide. Our results suggest that modified peptides can be useful in allergen immunotherapy.
Therapeutic vaccination with a trivalent T‐cell receptor (TCR) peptide vaccine restores deficient FoxP3 expression and TCR recognition in subjects with multiple sclerosis
Authors: Vandenbark Arthur A. , Culbertson Nicole E. , Bartholomew Richard M. , Huan Jianya , Agotsch Marci , LaTocha Dorian , Yadav Vijayshree , Mass Michele , Whitham Ruth , Lovera Jesus , Milano June , Theofan Georgia , Chou Yuan K. , Offner Halina , Bourdette Dennis N.
Published: October 2007

Therapeutic vaccination using T‐cell receptor (TCR) peptides from V genes commonly expressed by potentially pathogenic T cells remains an approach of interest for treatment of multiple sclerosis (MS) and other autoimmune diseases. We developed a trivalent TCR vaccine containing complementarity determining region (CDR) 2 peptides from BV5S2, BV6S5 and BV13S1 emulsified in incomplete Freund's adjuvant that reliably induced high frequencies of TCR‐specific T cells. To evaluate induction of regulatory T‐cell subtypes, immunological and clinical parameters were followed in 23 treatment‐naïve subjects with relapsing‐remitting or progressive MS who received 12 monthly injections of the trivalent peptide vaccine over 1 year in an open‐label study design. Prior to vaccination, subjects had reduced expression of forkhead box (Fox) P3 message and protein, and reduced recognition of the expressed TCR repertoire by TCR‐reactive cells compared with healthy control donors. After three or four injections, most vaccinated MS subjects developed high frequencies of circulating interleukin (IL)‐10‐secreting T cells specific for the injected TCR peptides and significantly enhanced expression of FoxP3 by regulatory T cells present in both ‘native’ CD4+ CD25+ and ‘inducible’ CD4+ CD25− peripheral blood mononuclear cells (PBMC). At the end of the trial, PBMC from vaccinated MS subjects retained or further increased FoxP3 expression levels, exhibited significantly enhanced recognition of the TCR V gene repertoire apparently generated by perturbation of the TCR network, and significantly suppressed neuroantigen but not recall antigen responses. These findings demonstrate that therapeutic vaccination using only three commonly expressed BV gene determinants can induce an expanded immunoregulatory network in vivo that may optimally control complex autoreactive responses that characterize the inflammatory phase of MS.
DEC‐205/CD205+ dendritic cells are abundant in the white pulp of the human spleen, including the border region between the red and white pulp
Authors: Pack Maggi , Trumpfheller Christine , Thomas Dolca , Park Chae Gyu , Granelli‐Piperno Angela , Münz Christian , Steinman Ralph M.
Published: October 2007

The distribution of dendritic cells (DCs) and macrophages in the human spleen has received less attention than that of lymphocytes. Here we have addressed this problem with the human DEC‐205/CD205 marker (‘DEC’), which is an endocytic receptor on DCs that mediates efficient presentation of antigens. DEC was abundant on dendritic profiles in the white pulp but absent from the red pulp, the latter defined with antibodies to two antigens, mannose receptor/CD206 on sinusoidal lining cells, and macrosialin/CD68 on macrophages. Double staining with anti‐DEC and anti‐CD3 showed the expected concentration of DEC+ cells in the relatively small T‐cell areas of the human spleen. DEC+ cells were also found in other regions of the white pulp. In all regions, the DEC+ cells were positive for major histocompatibility complex (MHC) class II and the CD11c integrin but largely immature, with low expression of B7‐2/CD86 costimulator and DC‐lysosome‐associated membrane protein (LAMP)/CD208. When we concentrated on the perifollicular region between the red pulp and the marginal zone, we found macrophages that stained with antibodies to sialoadhesin/CD169 and DC‐specific ICAM‐3 grabbing non‐integrin (SIGN)/CD209, and just inside these cells were DEC+ profiles. The DEC+ DCs were intertwined with cells that stained for the vascular addressin mucosal addressin cell adhesion molecule (MAdCAM). Therefore, anti‐DEC‐205/CD205 antibodies are useful for identifying DCs in human splenic white pulp and its border region with the red pulp.
Dealing with overdispersed count data in applied ecology
Authors: Richards Shane A.
Published: October 2007

The ability to identify key ecological processes is important when solving applied problems. Increasingly, ecologists are adopting Akaike's information criterion (AIC) as a metric to help them assess and select among multiple process‐based ecological models. Surprisingly, however, it is still unclear how best to incorporate AIC into the selection process in order to address the trade‐off between maximizing the probability of retaining the most parsimonious model while minimizing the number of models retained.

Ecological count data are often observed to be overdispersed with respect to best‐fitting models. Overdispersion is problematic when performing an AIC analysis, as it can result in selection of overly complex models which can lead to poor ecological inference. This paper describes and illustrates two approaches that deal effectively with overdispersion. The first approach involves modelling the causes of overdispersion implicitly using compound probability distributions. The second approach ignores the causes of overdispersion and uses quasi‐AIC (QAIC) as a metric for model parsimony.

Simulations and a novel method that identifies the most parsimonious model are used to demonstrate the utility of the two overdispersion approaches within the context of two ecological examples. The first example addresses binomial data obtained from a study of fish survival (as related to habitat structure) and the second example addresses Poisson data obtained from a study of flower visitation by nectarivores.

Applying either overdispersion approach reduces the chance of selecting overly complex models, and both approaches result in very similar ecological inference. In addition, inference can be made more reliable by incorporating model nesting into the selection process (i.e. identifying which models are special cases of others), as it reduces the number of models selected without significantly reducing the probability of retaining the most parsimonious models.

Synthesis and applications. When data are overdispersed, inference can be improved by either modelling the causes of overdispersion or applying QAIC as a metric for model parsimony. Inference can also be improved by adopting a model filtering procedure based on how models are nested. The general simulation approach presented in this paper for identifying the most parsimonious model, as defined by information theory, should help to improve our understanding of the reliability of model selection when using AIC, and help the development of better selection rules.
When does spatial structure matter in models of wildlife harvesting?
Authors: Ling S. , Milner‐Gulland E. J.
Published: October 2007

The most broadly applied generalizations of bioeconomics derive from simple, non‐spatial models. We develop a simple continuous spatial model in which harvesting costs are broken down into travel costs to a location and capture costs at that location within a harvested region.

This is used to determine the conditions under which the spatial behaviour of harvesters is important and its implications, particularly for the assessment of maximum achievable sustainable yield (MASY) and the optimal management of exploited animal populations.

The model suggests that, as a rule of thumb for harvested systems where density dependence is essentially a local process and harvesters act as independent agents, spatial structure will cause a significant impact on the dynamics and reduction in productivity of the system where the ratio of maximum travel cost to minimum capture cost is around 5 or more, and a very large impact where that ratio is around 10 or more.

Also, in a spatial harvesting system, secure ownership rights will not result in socially efficient harvesting if the owner only exercises control over overall offtake levels. Efficient management requires control of the spatial pattern of harvesting as well.

Synthesis and applications. These findings apply in cases where the spatial scale over which density dependence acts on the exploited population is limited in relation to the extent of the potential harvesting area, and where harvesters act as independent agents, choosing individually where to harvest. In most systems these conditions will not apply perfectly, and in many cases they may be seriously violated, but the rule of thumb above may be used quickly to establish whether spatial structure should warrant further investigation. In managed systems where harvesting decisions are regulated, the model may still be used to understand the gains produced by management.
Modelling species distributions using regression quantiles
Authors: Vaz Sandrine , Martin Corinne S. , Eastwood Paul D. , Ernande Bruno , Carpentier Andre , Meaden Geoff J. , Coppin Frank
Published: October 2007

Species distribution modelling is an important and well‐established tool for conservation planning and resource management. Modelling techniques based on central estimates of species responses to environmental factors do not always provide ecologically meaningful estimates of species–environment relationships and are being increasingly questioned.

Regression quantiles (RQ) can be used to model the upper bounds of species–environment relationships and thus estimate how the environment is limiting the distribution of a species. The resulting models tend to describe potential rather than actual patterns of species distributions.

Model selection based on null hypothesis testing and backward elimination, followed by validation procedures, are proposed here as a general approach for constructing RQ limiting effect models for multiple species.

This approach was applied successfully to 16 of the most abundant marine fish and cephalopods in the eastern English Channel. Most models were validated successfully and null hypothesis testing for model selection proved effective for RQ modelling.

 Synthesis and applications. Modelling the upper bounds of species‐habitat relationships enables the detection of the effects of limiting factors on species’ responses. Maps showing potential species distributions are also less likely to underestimate species responses’ to the environment, and therefore have subsequent benefits for precautionary management.
Validation of an evaluation model for learning management systems
Authors: Kim S.W. , Lee M.G.
Published: October 2007

Abstract  This study aims to validate a model for evaluating learning management systems (LMS) used in e‐learning fields. A survey of 163 e‐learning experts, regarding 81 validation items developed through literature review, was used to ascertain the importance of the criteria. A concise list of explanatory constructs, including two principle factors, was extracted from the responses of 133 respondents by exploratory factor analysis. Factor I was labeled as ‘instruction management, screen design, and technology’ and factor II, ‘interaction and evaluation’. Factors I and II consisted of four and three sub‐factors, respectively. Confirmatory factor analysis, in turn, was carried out to assess the degree to which the plausibility of factor models was empirically confirmed. Overall fit measures (RMSEA, CFI, NNFI indexes) showed the model to be quite suitable for LMS evaluation. Reliability estimates using Cronbach's alpha indicated that the evaluation tool had good internal consistency. The overall results of the analyses suggest that this evaluation tool is highly instrumental for LMS.
Importance of seafood as nutrient source in the diet of Belgian adolescents
Authors: Sioen I. , Matthys C. , De Backer G. , Van Camp J. , Henauw S. De
Published: October 2007

Background  Regular seafood consumption is recommended in dietary guidelines. The aim of this study was to investigate the importance of seafood as a nutrient source in adolescents’ diet and the extent to which seafood consumption can increase the intake of omega‐3 polyunsaturated fatty acids and vitamin D.

Methods  Consumption data recorded during seven consecutive days for 341 adolescents selected in Ghent (Belgium) were used to estimate the intake of vitamin D, linoleic (LA), α‐linolenic (LNA), arachidonic (AA), eicosapentaenoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acid.

Results  The adolescents consumed on average 3.21 μg/day vitamin D, 11.7 g/day LA and 1.4 g/day LNA. The mean intakes of AA, EPA, DPA and DHA were 83.2, 55.9, 18.4 and 111.4 mg/day respectively. The major source of vitamin D was fortified margarine. Fats and oils were the main sources for LA and LNA. The intake of AA was mainly contributed by meat, poultry and eggs. Fish and seafood contributed for 84.1%, 59.3% and 64.4% respectively for EPA, DPA and DHA.

Conclusion  Flemish adolescents would benefit from increased seafood consumption, as this would lead to a higher intake of EPA and DHA as well as of vitamin D. Moreover, replacement of foods rich in saturated fat (SFA) by seafood products can help to reduce SFA intake.
Trainee health care professionals’ knowledge of the health risks associated with obesity
Authors: Swift J. A. , Sheard C. , Rutherford M.
Published: October 2007

Background  Trainee nurses, doctors and dietitians will direct the future of obesity treatment and prevention. To do so effectively, they must have sufficient knowledge regarding the health risks associated with obesity and feel that part of their professional role is to counsel obese patients regarding these risks.

Methods  An online survey collected data on professional roles, training needs and the Obesity Risk Knowledge‐10 (ORK‐10) scale from 38 dietetic, 88 nursing (Diploma), 74 nursing (Masters) and 389 medical students.

Results  Final‐year dietetic students demonstrated higher ORK‐10 scale scores than final‐year nursing (Dip), nursing (MSc) and medical students (P < 0.001). The majority of students agreed that part of their profession’s role was to counsel obese patients about the health risks associated with obesity. Dietetic students were more satisfied with the teaching they had received than each of the other student groups (P < 0.05).

Conclusion  Future health care professionals recognize their responsibility to communicate health risk information to obese patients. Dietetic students have a sound knowledge base to support them in this. Educators of trainee nurses and doctors may like to respond to their students’ lower levels of knowledge and desire for more training.
Quality of life in adult enteral tube feeding patients
Authors: Brotherton A. M. , Judd P. A.
Published: October 2007

Background  Enteral tube feeding may impact significantly on patients’ quality of life (QoL). The aim of this paper is to review studies that have measured QoL in adult patients receiving enteral tube feeding to determine the factors that are associated with feeding that impact on the patients’ QoL.

Methods  An electronic search of CINAHL, MEDLINE and EMBASE was undertaken to identify articles that had measured QoL in adults receiving enteral tube feeding.

Results  Ten studies were included in the review. Quality of life in patients receiving enteral tube feeding generally appeared poor compared with control groups. Factors that were found to impact on patients’ quality of life included symptoms such as nausea, vomiting, diarrhoea and fatigue. Issues around body image, inability to go out and discomfort while carrying out activities of daily living also impacted on QoL.

Conclusions  Although the presence of underlying disease and the use of different QoL measures made comparison of the results difficult, issues requiring further consideration in clinical practice include effective symptom management, assessment of psychological and emotional issues and support for patients to enable them to cope with the resulting social isolation.
Vitamin K prescribing patterns and bone health surveillance in UK children with cystic fibrosis
Authors: Urquhart D. S. , Fitzpatrick M. , Cope J. , Jaffe A.
Published: October 2007

Background  Bone disease has become an increasingly recognized complication of cystic fibrosis (CF). Although causes of CF bone disease are multifactorial, there has been recent interest in the role of vitamin K in CF bone disease.

Aims and methods  A questionnaire survey of all UK paediatric CF centre dietitians and centre directors was carried out to ascertain current practice with regard to vitamin K prescribing and bone health surveillance.

Results  The survey had a 97% response rate representing 3414 CF children. Twenty‐three centre directors and 19 dietitians responded, and at least moderate agreement was noted with kappa scores >0.41 for all but one question assessed. Ninety‐three per cent centres report that >90% pancreatic insufficient patients receive vitamins A, D and E, yet only 18% centres routinely supplement vitamin K. The majority (60%) report that <10% of their CF patients receive vitamin K, whilst vitamin K dosage varied from 0.3–0.5 to 10 mg day−1. Only one centre undertook no bone health surveillance, and vitamin D levels are measured in 89%, calcium intake assessed in 82% and dual‐energy X‐ray absorptiometry scans performed in 61% centres.

Discussion  Heterogeneity in both vitamin K prescribing practices and bone health surveillance in CF across the UK were noted, underlining the need for a national consensus on bone health management, as well as acting as a call for longitudinal research into the clinical effectiveness of vitamin K therapy in CF.
Pillars of Hercules: is the Atlantic–Mediterranean transition a phylogeographical break?
Authors: PATARNELLO TOMASO , VOLCKAERT FILIP A. M. J. , CASTILHO RITA
Published: October 2007

The geological history of the Mediterranean Sea, its hydrography and connection with the Atlantic Ocean have been well documented. Despite a wealth of historical and oceanographic data, the Atlantic–Mediterranean transition remains controversial at the biological level as there are discordant results regarding the biogeographical separation between the Atlantic and Mediterranean biota. The opening of the Strait of Gibraltar at the end of the Messinian Salinity Crisis (some 5.33 million years ago), removed the land barrier that impeded the marine biota allowing it to disperse freely into the Mediterranean Sea. However, present day genetic patterns suggest a limitation to gene flow for some marine species, preventing population admixture. In the last few years, a large number of studies have challenged the hypothesis of the Strait of Gibraltar representing a phylogeographical break. A review of more than 70 papers reveals no obvious relationship between either dispersal ability or life history, and observed patterns of partial or complete genetic isolation between Atlantic and Mediterranean populations. We re‐analysed a selection of this large body of data (20 studies in total) in order to provide a homogeneous and coherent view on the generality of the phylogeographical patterns and the presence of a phylogeographical barrier. This offered the opportunity to summarize the state of the art on this matter and reach some general conclusions on the evolutionary history across the Atlantic–Mediterranean range. Geographically, some species in the transition zone showed step changes of allele frequencies associated with the Almeria‐Oran Front rather than with the Strait of Gibraltar itself. A major part of the data describe evolutionary events well within the time frame of the Quaternary age as very few taxa pre‐date closure of the Tethys Sea. Results point to a combined signature of vicariance, palaeoclimate fluctuation and life‐history traits on the Atlantic–Mediterranean phylogeographical patterns. Principal component analysis failed to show any particular association between biological traits and genetic variables. It would argue that organismal determinism may play a far less significant role than marine biogeographers have generally believed.
Population structure and gene flow reversals in Atlantic salmon (Salmo salar) over contemporary and long‐term temporal scales: effects of population size and life history
Authors: PALSTRA FRISO P. , O’CONNELL MICHAEL F. , RUZZANTE DANIEL E.
Published: October 2007

Metapopulation dynamics are increasingly invoked in management and conservation of endangered species. In this context, asymmetrical gene flow patterns can be density dependent, with migration occurring mainly from larger into smaller populations, which may depend on it for their persistence. Using genetic markers, such patterns have recently been documented for various organisms including salmonids, suggesting this may be a more general pattern. However, metapopulation theory does not restrict gene flow asymmetry to ‘source‐sink’ structures, nor need these patterns be constant over longer evolutionary timescales. In anadromous salmonids, gene flow can be expected to be shaped by various selective pressures underlying homing and dispersal (‘straying’) behaviours. The relative importance of these selective forces will vary spatially and for populations of different census size. Furthermore, the consequences of life‐history variation among populations for dispersal and hence gene flow remain poorly quantified. We examine population structure and connectivity in Atlantic salmon (Salmo salar L.) from Newfoundland and Labrador, a region where populations of this species are relatively pristine. Using genetic variation at 13 microsatellite loci from samples (N = 1346) collected from a total of 20 rivers, we examine connectivity at several regional and temporal scales and test the hypothesis that the predominant direction of gene flow is from large into small populations. We reject this hypothesis and find that the directionality of migration is affected by the temporal scale over which gene flow is assessed. Whereas large populations tend to function as sources of dispersal over contemporary timescales, such patterns are often changed and even reversed over evolutionary, coalescent‐derived timescales. These patterns of population structure furthermore vary between different regions and are compatible with demographic and life‐history attributes. We find no evidence for sex‐biased dispersal underlying gene flow asymmetry. Our findings caution against generalizations concerning the directionality of gene flow in Atlantic salmon and emphasize the need for detailed regional study, if such information is to be meaningfully applied in conservation and management of salmonids.
Genetic evidence that culling increases badger movement: implications for the spread of bovine tuberculosis
Authors: POPE LISA C. , BUTLIN ROGER K. , WILSON GAVIN J. , WOODROFFE ROSIE , ERVEN KRISTIEN , CONYERS CHRIS M. , FRANKLIN TANYA , DELAHAY RICHARD J. , CHEESEMAN CHRIS L. , BURKE TERRY
Published: October 2007

The Eurasian badger (Meles meles) has been implicated in the transmission of bovine tuberculosis (TB, caused byMycobacterium bovis) to cattle. However, evidence suggests that attempts to reduce the spread of TB among cattle in Britain by culling badgers have mixed effects. A large‐scale field experiment (the randomized badger culling trial, RBCT) showed that widespread proactive badger culling reduced the incidence of TB in cattle within culled areas but that TB incidence increased in adjoining areas. Additionally, localized reactive badger culling increased the incidence of TB in cattle. It has been suggested that culling‐induced perturbation of badger social structure may increase individual movements and elevate the risk of disease transmission between badgers and cattle. Field studies support this hypothesis, by demonstrating increases in badger group ranges and the prevalence of TB infection in badgers following culling. However, more evidence on the effect of culling on badger movements is needed in order to predict the epidemiological consequences of this control strategy. Here, analysis of the genetic signatures of badger populations in the RBCT revealed increased dispersal following culling. While standard tests provided evidence for greater dispersal after culling, a novel method indicated that this was due to medium‐ and long‐distance dispersal, in addition to previously reported increases in home‐range size. Our results also indicated that, on average, badgers infected withM. bovismoved significantly farther than did uninfected badgers. A disease control strategy that included culling would need to take account of the potentially negative epidemiological consequences of increased badger dispersal.
No relationship between individual genetic diversity and prevalence of avian malaria in a migratory kestrel
Authors: ORTEGO JOAQUÍN , CORDERO PEDRO J. , APARICIO JOSÉ MIGUEL , CALABUIG GUSTAU
Published: October 2007

Insight into the genetic basis of malaria resistance is crucial for understanding the consequences of this parasite group on animal populations. Here, we analyse the relationship between genotypic variation at 11 highly variable microsatellite loci and prevalence of three different lineages of avian malaria, two Plasmodium (RTSR1, LK6) and one Haemoproteus (LK2), in a wild population of the endangered lesser kestrel (Falco naumanni). Although we used a large sample size (584 typed individuals), we did not find any significant association between the prevalence of the studied parasite lineages and individual genetic diversity. Although our data set is large, the 11 neutral markers typed may have had low power to detect such association, in part because of the low parasite prevalence observed (less than 5% of infected birds). However, the fact that we have detected previous correlations between genetic diversity and other traits (ectoparasitism risk, fecundity) in the study population using the same panel of neutral markers and lower sample sizes suggests that other factors could underlie the absence of such a similar correlation with avian malaria. Differences in the genetics of the studied traits and in their particular basis of inbreeding depression (dominance vs. overdominance) may have led to malaria prevalence, but not other traits, being uncoupled with individual genetic diversity. Also, we cannot discard the possibility that the absence of association was a consequence of a low pathogenic effect of these particular malaria lineages on our lesser kestrel population, and thus we should not expect the evolution of genetic resistance against these parasites.
Deep genetic divergences in Aoraki denticulata (Arachnida, Opiliones, Cyphophthalmi): a widespread ‘mite harvestman’ defies DNA taxonomy
Authors: BOYER SARAH L. , BAKER JESSICA M. , GIRIBET GONZALO
Published: October 2007

Aoraki denticulata (Arachnida, Opiliones, Cyphophthalmi, Pettalidae), a widespread ‘mite harvestman’ endemic to the South Island of New Zealand, is found in leaf littler habitats throughout Nelson and Marlborough, and as far south as Arthur's Pass. We investigated the phylogeography and demographic history of A. denticulata in the first genetic population‐level study within Opiliones. A total of 119 individuals from 17 localities were sequenced for 785 bp of the gene cytochrome c oxidase subunit I; 102 of these individuals were from the Aoraki subspecies A. denticulata denticulata and the remaining 17 were from the subspecies A. denticulata major. An extraordinarily high degree of genetic diversity was discovered in A. denticulata denticulata, with average uncorrected p‐distances between populations as high as 19.2%. amova, average numbers of pairwise differences, and pairwise FST values demonstrated a significant amount of genetic diversity both within and between populations of this subspecies. Phylogenetic analysis of the data set revealed many well‐supported groups within A. denticulata denticulata, generally corresponding to clusters of specimens from single populations with short internal branches, but separated by long branches from individuals from other populations. No haplotypes were shared between populations of the widespread small subspecies, A. denticulata denticulata. These results indicate a subspecies within which very little genetic exchange occurs between populations, a result consistent with the idea that Cyphophthalmi are poor dispersers. The highly structured populations and deep genetic divergences observed in A. denticulata denticulata may indicate the presence of cryptic species. However, we find a highly conserved morphology across sampling localities and large genetic divergences within populations from certain localities, equivalent to those typically found between populations from different localities. Past geological events may have contributed to the deep genetic divergences observed between sampling localities; additionally, the high divergence within populations of A. denticulata denticulata suggests that the rate of COI evolution may be accelerated in this taxon. In contrast, the larger subspecies A. denticulata major shows much less differentiation between and within sampling localities, suggesting that it may disperse more easily than its smaller counterpart. The fact that the remarkable genetic divergences within populations of A. denticulata denticulata from certain localities are equivalent to divergences between localities poses a challenge to the rapidly spreading practice of DNA taxonomy
Patterns of genetic diversity and candidate genes for ecological divergence in a homoploid hybrid sunflower,Helianthus anomalus
Authors: SAPIR YUVAL , MOODY MICHAEL L. , BROUILLETTE LARRY C. , DONOVAN LISA A. , RIESEBERG LOREN H.
Published: October 2007

Natural hybridization accompanied by a shift in niche preference by hybrid genotypes can lead to hybrid speciation. Natural selection may cause the fixation of advantageous alleles in the ecologically diverged hybrids, and the loci experiencing selection should exhibit a reduction in allelic diversity relative to neutral loci. Here, we analyzed patterns of genetic diversity at 59 microsatellite loci associated with expressed sequence tags (ESTs) in a homoploid hybrid sunflower species,Helianthus anomalus. We used two indices, ln RVand ln RH, to compare variation and heterozygosity (respectively) at each locus between the hybrid species and its two parental species,H. annuusandH. petiolaris. Mean values of ln RVand ln RHwere significantly lower than zero, which implies thatH. anomalusexperienced a population bottleneck during its recent evolutionary history. After correcting for the apparent bottleneck, we found six loci with a significant reduction in variation or with heterozygosity in the hybrid species, compared to one or both of the parental species. These loci should be viewed as a ranked list of candidate loci, pending further sequencing and functional analyses. Sequence data were generated for two of the candidate loci, but population genetics tests failed to detect deviations from neutral evolution at either locus. Nonetheless, a greater than eight‐fold excess of nonsynonymous substitutions was found near a putative N‐myristoylation motif at the second locus (HT998), and likelihood‐based models indicated that the protein has been under selection inH. anomalusin the past and, perhaps, in one or both parental species. Finally, our data suggest that selective sweeps may have united populations ofH. anomalusisolated by a mountain range, indicating that even low gene‐flow species may be held together by the spread of advantageous alleles.
Trans‐Arctic dispersals and the evolution of a circumpolar marine fish species complex, the capelin (Mallotus villosus)
Authors: DODSON JULIAN J. , TREMBLAY SUZY , COLOMBANI FRANÇOISE , CARSCADDEN JAMES E. , LECOMTE FREDERIC
Published: October 2007

Trans‐Arctic dispersals and population and range expansions during the Pleistocene enhanced opportunities for evolutionary diversification and contributed to the process of speciation within the capelin, a northern marine‐fish complex exhibiting a circumpolar distribution. Capelin is composed of four highly divergent and geographically discrete mitochondrial DNA (mtDNA) clades (609 bp; cytochrome b). Two clades occur in the North Atlantic, one associated with Canadian Atlantic waters, including Hudson Bay, and the second distributed from West Greenland to the Barents Sea. Two additional clades occur in the Arctic and northeast Pacific Oceans, representing the most recent divergence within the capelin phylogenetic tree. Judged from mtDNA diversity, capelin populations comprising all clades experienced at least one demographic and spatial reduction–expansion episode during recent Pleistocene glaciations that imprinted their molecular architecture. The large contemporary populations in the northeast Pacific and Arctic Oceans exhibited significant genetic structure whereas no such structure was detected in the equally extensive North Atlantic clades. All clades are characterized by one or two prevalent mtDNA haplotypes distributed over the entire range of the clade. Assuming a Pacific ancestor for capelin, we infer that capelin dispersed on two separate occasions to the North Atlantic. A more recent event resulted in the isolation of eastern Pacific and Arctic clades, with the Arctic clade positioned for a potential third Atlantic invasion, as revealed by the presence of this clade in the Labrador Sea. The Labrador Sea is a potential contact zone for three of the four capelin clades.
Crystal structure of the Leishmania major phosphodiesterase LmjPDEB1 and insight into the design of the parasite‐selective inhibitors
Authors: Wang Huanchen , Yan Zier , Geng Jie , Kunz Stefan , Seebeck Thomas , Ke Hengming
Published: October 2007

Human leishmaniasis is a major public health problem in many countries, but chemotherapy is in an unsatisfactory state. Leishmania major phosphodiesterases (LmjPDEs) have been shown to play important roles in cell proliferation and apoptosis of the parasite. Thus LmjPDE inhibitors may potentially represent a novel class of drugs for the treatment of leishmaniasis. Reported here are the kinetic characterization of the LmjPDEB1 catalytic domain and its crystal structure as a complex with 3‐isobutyl‐1‐methylxanthine (IBMX) at 1.55 Å resolution. The structure of LmjPDEB1 is similar to that of human PDEs. IBMX stacks against the conserved phenylalanine and forms a hydrogen bond with the invariant glutamine, in a pattern common to most inhibitors bound to human PDEs. However, an extensive structural comparison reveals subtle, but significant differences between the active sites of LmjPDEB1 and human PDEs. In addition, a pocket next to the inhibitor binding site is found to be unique to LmjPDEB1. This pocket is isolated by two gating residues in human PDE families, but constitutes a natural expansion of the inhibitor binding pocket in LmjPDEB1. The structure particularity might be useful for the development of parasite‐selective inhibitors for the treatment of leishmaniasis.
Effect of chronic, extrinsic denervation on functional NANC innervation with vasoactive intestinal polypeptide and substance P in longitudinal muscle of rat jejunum1
Authors: Kasparek M. S. , Fatima J. , Iqbal C. W. , Duenes J. A. , Sarr M. G.
Published: October 2007

Abstract Intestinal denervation contributes to enteric motor dysfunction after intestinal transplantation [small bowel transplantation (SBT)]. Our aim was to determine long‐term effects of extrinsic denervation on functional non‐adrenergic, non‐cholinergic innervation with vasoactive intestinal polypeptide (VIP) and substance P. Contractile activity of jejunal longitudinal muscle from six age‐matched, naïve control rats (NC) and eight rats 1 year after syngeneic SBT were studied in tissue chambers. Spontaneous contractile activity did not differ between groups. Exogenous VIP inhibited contractile activity dose‐dependently in both groups, greater in NC than in SBT. The VIP antagonist ([d‐p‐Cl‐Phe6,Leu17]‐VIP) and the nitric oxide synthase inhibitorl‐NG‐nitro arginine prevented inhibition by exogenous VIP and electrical field stimulation (EFS) in both groups. Exogenous substance P increased contractile activity dose‐dependently, greater in NC than in SBT. The substance P antagonist ([d‐Pro2,d‐Trp7,9]‐substance P) inhibited effects of exogenous substance P and increased the EFS‐induced inhibitory response. Immunohistofluorescence showed staining for tyrosine hydroxylase in the jejunoileum 1 year after SBT suggesting sympathetic reinnervation. In rat jejunal longitudinal muscle after chronic denervation, response to exogenous VIP and substance P is decreased, while endogenous release of both neurotransmitters is preserved. These alterations in excitatory and inhibitory pathways occur despite extrinsic reinnervation and might contribute to enteric motor dysfunction after SBT.
Diabetes and the enteric nervous system
Authors: Chandrasekharan B. , Srinivasan S.
Published: October 2007

Abstract  Diabetes is associated with several changes in gastrointestinal (GI) motility and associated symptoms such as nausea, bloating, abdominal pain, diarrhoea and constipation. The pathogenesis of altered GI functions in diabetes is multifactorial and the role of the enteric nervous system (ENS) in this respect has gained significant importance. In this review, we summarize the research carried out on diabetes‐related changes in the ENS. Changes in the inhibitory and excitatory enteric neurons are described highlighting the role of loss of inhibitory neurons in early diabetic enteric neuropathy. The functional consequences of these neuronal changes result in altered gastric emptying, diarrhoea or constipation. Diabetes can also affect GI motility through changes in intestinal smooth muscle or alterations in extrinsic neuronal control. Hyperglycaemia and oxidative stress play an important role in the pathophysiology of these ENS changes. Antioxidants to prevent or treat diabetic GI motility problems have therapeutic potential. Recent research on the nerve–immune interactions demonstrates inflammation‐associated neurodegeneration which can lead to motility related problems in diabetes.