bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of secondary Production and its components to multiple stressors in nematode field populations
Authors: DOROSZUK AGNIESZKA , TE BRAKE ELSKE , CRESPO‐GONZALEZ DAVID , KAMMENGA JAN E.
Published: February 2007

Realistic measures of the impact of individual or multiple stressors are important for ecological risk assessment. Although multiple anthropogenic stressors are common in human‐dominated environments, knowledge of their influence on functional population parameters such as secondary production (P) and biomass turnover (P/B) is very limited. Secondary production integrates population characteristics such as biomass, size–frequency distribution and body growth rate, and provides a link between population and system ecologies.

The influence of copper and pH stress on yearly secondary production and biomass turnover of field populations of the nematode Acrobeloides nanus was investigated by using a randomized factorial block design. The responses of the components of secondary production were also analysed in order to elucidate the mechanisms underlying the change in secondary production.

Secondary production and biomass turnover showed reduced values in soil of low pH. A negative effect of copper on both parameters was observed only when the copper load was combined with low pH, otherwise higher copper concentrations resulted in higher secondary production and biomass turnover.

The observed response of production and biomass turnover was mainly driven by changes in mean relative growth rate (MRGR), a measure of body growth rate estimated in a laboratory soil experiment. The biomass was higher on average in the plots with high copper load, while no significant response to pH was found.

Synthesis and applications. Our results demonstrate that populations of soil organisms may experience strong synergistic effects of combined stressors (acidification and copper stress) on functional population parameters while showing no detrimental effects on biomass. Moreover, the effects on secondary production and biomass turnover rate are predominantly driven by effects on body growth rate. We recommend that ecological risk assessment methodologies should include consideration of soil contamination on the basis of conservation of functional properties of ecosystems and their key components.
Competitive dynamics in two‐ and three‐component intercrops
Authors: ANDERSEN METTE KLINDT , HAUGGAARD‐NIELSEN HENRIK , WEINER JACOB , JENSEN ERIK STEEN
Published: February 2007

Intercropping is receiving increasing attention because it offers potential advantages for resource utilization, decreased inputs and increased sustainability in crop production, but our understanding of the interactions among intercropped species is still very limited.

We grew peaPisum sativum, barleyHordeum vulgareand rapeBrassica napusas sole crops and intercrops under field conditions using a replacement design. We collected total dry matter data from sequential harvests and fitted the data to a logistic growth model. At each harvest we estimated the relative Competitive Strength (CS) of the three crops by fitting the data to a simple interspecific competition model.

The pea monocrop produced the largest amount of biomass from the middle to the end of the growth period, but pea was not dominant in intercrops.

Fitting data to a logistic growth model emphasizes the importance of initial size differences for interactions among intercrops. Barley was the dominant component of the intercrops largely because of its initial size advantage. The competitive effect of barley on its companion crops, measured as CS, increased throughout most of the growing season.

The performance of each crop species was very different when it grew with a second species rather than in monoculture, but addition of a third crop species had only minor effects on behaviour of the individual crops.

Synthesis and applications.Including sequential harvests in experiments on intercropping can provide important information about how competitive hierarchies are established and change over time. Our results suggest that increased understanding of the role of asymmetric competition among species and the resulting advantages of early germination and seedling emergence would be valuable in designing intercrops. More focus on understanding the mechanisms that govern interactions between intercropped species is needed for designing optimized intercropping systems.
Operationalizing quality of life for people with profound multiple disabilities: a Delphi study
Authors: Petry K. , Maes B. , Vlaskamp C.
Published: February 2007

Background  In a recent study, we constructed an item pool that contains items on the quality of life (QOL) and related aspects of support of people with profound multiple disabilities (PMD). In the present study, a panel of experts assessed the content and the structure of this item pool in order to enhance its validity and usefulness.

Method  A two‐round Delphi study was set up. The panel consisted of 45 experts, of whom 12 were theory‐experts, 12 practice‐experts and 12 experience‐experts from Belgium (n = 12), Germany (n = 12), the Netherlands (n = 11) and the UK/Ireland (n = 10). Both quantitative and qualitative methods of analysis were applied to the data.

Results  The majority of the items were considered relevant for the QOL of people with PMD. In the first round, 91% of the items reached the 80% criterion of consensus. In the second round, 78.7% of the items reached the 85% criterion of consensus. There were no significant differences in opinion neither between types of experts nor between countries. Several items were reported as missing in the item pool and were added.

Conclusions  The results provide some evidence that the item pool is a valid operationalization of QOL of people with PMD and can be used in an instrument to measure the QOL of this target group.
Elevated concentrations of asymmetric dimethylarginine are associated with deterioration of glucose tolerance in women with previous gestational diabetes mellitus
Authors: Mittermayer F. , Kautzky‐Willer A. , Winzer C. , Krzyzanowska K. , Prikoszovich T. , Demehri S. , Wagner O. , Wolzt M.
Published: February 2007

Objective.  Women with previous gestational diabetes mellitus (GDM) have a high risk for development of type 2 diabetes mellitus. The endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) could be related to disorders of the glucose metabolism. To evaluate if ADMA predicts deterioration of glucose tolerance in women with previous GDM and to assess concentration changes we analysed ADMA in women with previous GDM after delivery and after a median follow‐up of 2.75 years (interquartile range: 1.47–4.60).

Design.  Prospective cohort study.

Subjects and methods.  ADMA, symmetric dimethylarginine (SDMA) and l‐arginine were determined in 77 women with previous GDM who underwent a 75‐g oral glucose tolerance test 4 months after delivery and at follow‐up.

Results.  Deterioration in glucose tolerance was observed in 36% of the women with ADMA above and 11% of those with ADMA below the median (0.56 μmol L−1; P = 0.008, log‐rank test). ADMA correlated significantly with mean arterial blood pressure and nonsignificantly with body mass index (P = 0.050) but not with insulin resistance, fasting glucose, lipids or glomerular filtration rate. The fully adjusted hazard ratio for a decline of glucose tolerance during follow‐up was 3.94 (95% CI: 1.16–13.37; P = 0.028) for subjects with ADMA above the median. SDMA and l‐arginine were not associated with changes in the glucose tolerance status. ADMA and l‐arginine decreased significantly during follow‐up.

Conclusions.  High serum ADMA after delivery is associated with deterioration in glucose tolerance in women with previous GDM and declines in the following years.
Metabolic syndrome, its preeminent clusters, incident coronary heart disease and all‐cause mortality – results of prospective analysis for the Atherosclerosis Risk in Communities study
Authors: Hong Y. , Jin X. , Mo J. , Lin H.‐M. , Duan Y. , Pu M. , Wolbrette D. L. , Liao D.
Published: February 2007

Objective.  To investigate the prospective association between Metabolic Syndrome (MetS) and coronary heart disease (CHD) and all‐cause mortality.

Subjects and Design.  A bi‐racial cohort of 14 699 middle‐aged Americans from the Atherosclerosis Risk in Communities study were followed for the development of new CHD and death over a period of 9 years. MetS, using the original ATP‐III criteria, was defined as having at least three of the following components: elevated blood pressure (BP), elevated plasma glucose, elevated blood triglyceride (TG), increased waist circumference, and low HDL cholesterol (HDL‐c). Incident CHD cases included hospitalized myocardial infarction (MI), fatal CHD, revascularization procedures, and silent MI as detected by EKG.

Results.  The prevalence of the MetS at baseline was 29%, 30%, 40% and 26% among CHD‐free white women, white men, black women, and black men, respectively. There were 1018 incident CHD cases and 1039 deaths. The relative risk (RR) and 95% confidence interval (CI) of incident CHD associated with MetS was 2.46 (1.99, 3.03) for women and 1.86 (1.59, 2.18) for men. Clear dose–response relationship between the number of MetS components and incidence of CHD was found (P for linear trend <0.001). The following three clusters of MetS components posed the highest risk for CHD: (i) the elevated BP and glucose and low HDL‐c group [RR = 5.68 (3.44, 9.37)]; (ii) the elevated BP and glucose and TG group [RR = 5.08 (2.96, 8.70)]; and (iii) the elevated BP and TG and low HDL‐c group [RR = 3.98 (2.75, 5.77)]. When all five components co‐existed, the risk was the highest [RR = 6.24 (4.65, 8.36)]. Similar results with attenuated RR were found for all‐cause mortality.

Conclusions.  Individuals, especially women, with the MetS have significantly higher risk of developing CHD. The riskiest combination is high‐BP and glucose clustered with low HDL‐c or high TG. These data highlight the importance of targeting MetS in the prevention of CHD and premature death.
Unique patient with cerebrotendinous xanthomatosis. Evidence for presence of a defect in a gene that is not identical to sterol 27‐hydroxylase
Authors: Hansson M. , Olin M. , Floren C.‐H. , Von Bahr S. , Van't Hooft F. , Meaney S. , Eggertsen G. , Björkhem I.
Published: February 2007

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder believed to be exclusively caused by mutations in the CYP27A1 gene coding for the enzyme sterol 27‐hydroxylase. Common findings in CTX are tendon xanthomas, cataracts and progressive neurological dysfunction. Here, we characterize an adult female patient with tendon xanthomas and classic biochemical findings of CTX (i.e. high levels of bile alcohols and cholestanol and extremely low levels of 27‐hydroxycholesterol in plasma). Additionally, sterol 27‐hydroxylase activity in cultured monocyte‐derived macrophages from this patient was <5% of normal. Sequencing the CYP27A1 gene uncovered that the patient is heterozygous for two previously undescribed base substitutions in exon 8, C478A and C479A, which are expected to affect the haeme‐binding domain of the enzyme. When expressed in HEK293 cells, the corresponding protein had only 8% of normal enzymatic activity. No other mutation was found in the open reading frame of the CYP27A1 gene, intron–exon boundaries or in the 5′‐untranslated region up to 5000 bp distal to the translational start site. Sequencing mRNA isolated from leucocytes from the patient revealed a 1 : 1 ratio of mutated and nonmutated species, with total mRNA levels that were not significantly different from the controls. It is concluded that the patient is heterozygous for two mutations affecting one allele of the CYP27A1 gene and with at least one additional yet undefined gene that is of critical importance for the activity of sterol 27‐hydroxylase.
Elemental distributions in femoral bone of rat under osteoporosis preventive treatments
Authors: YNSA M. D. , AGER F. J. , ALVES L. C. , ZUBELDIA M. A. , MILLÁN J. C. , PINHEIRO T.
Published: February 2007

One of the abnormalities of bone architecture is osteoporosis as occurring in post‐menopausal women. Especially long bones, such as femur, become more fragile and more prone to fracture. The efficiency of several osteoporosis preventative treatments based on oestrogen and progestin in bone structure and mineral recovery was studied using ovariectomized Wistar rats as an osteoporosis experimental model. Diagonal cross‐sections of the proximal epiphysis of femoral bones were analysed using nuclear microscopy techniques in order to map and determine the concentration profiles of P, Ca, S, Fe and Zn from the epiphysis to diaphysis and across the cortical and trabecular bone structures. In control animals (not ovariectomized), the S and Zn contents significantly characterized differences between cortical and trabecular bone structures, whereas P and Ca showed increased gradients from the epiphyseal region to the diaphysis. After ovariectomy the differences observed were differential according to the type of hormonal supplementation. A significant decrease in P and Ca contents and depletion of minor and trace minerals, such as S, Fe and Zn, were found for both cortical and trabecular bone structures after ovariectomy relative to controls. Bone mineral contents were reversed to control levels by synthetic oestrogen supplementation, and combined oestrogen and progesterone treatment. Recovery was more evident in the femoral epiphysis and neck than in the diaphysis. The use of oestrogen alone did not lead to bone recovery after ovariectomy. Alterations in bone mineral composition observed for animals receiving synthetic oestrogen and combined oestrogen and progesterone supplement might reflect beneficial structural changes in critical regions of long bones, mostly affected in post‐menopausal osteoporosis.
Gonadotrophin‐Releasing Hormone (GnRH) Release in Marmosets I: In Vivo Measurement in Ovary‐Intact and Ovariectomised Females
Authors: Tannenbaum P. L. , Schultz‐Darken N. J. , Saltzman W. , Terasawa E. , Woller M. J. , Abbott D. H.
Published: February 2007

In vivo hypothalamic gonadotrophin‐releasing hormone (GnRH) release was characterised for the first time in a New World primate. A nonterminal and repeatable push‐pull perfusion (PPP) technique reliably measured GnRH in conscious common marmoset monkeys. Nineteen adult females (n = 8 ovary‐intact in the mid‐follicular phase; n = 11 ovariectomised) were fitted with long‐term cranial pedestals, and a push‐pull cannula was temporarily placed in unique locations within the pituitary stalk‐median eminence (S‐ME) 2 days prior to each PPP session. Marmosets underwent 1–3 PPPs (32 PPPs in total) lasting up to 12 h. Plasma cortisol levels were not elevated in these habituated marmosets during PPP, and PPP did not disrupt ovulatory cyclicity or subsequent fertility in ovary‐intact females. GnRH displayed an organised pattern of release, with pulses occurring every 50.0 ± 2.6 min and lasting 25.4 ± 1.3 min. GnRH pulse frequency was consistent within individual marmosets across multiple PPPs. GnRH mean concentration, baseline concentration and pulse amplitude varied predictably with anatomical location of the cannula tip within the S‐ME. GnRH release increased characteristically in response to a norepinephrine infusion and decreased abruptly during the evening transition to lights off. Ovary‐intact (mid‐follicular phase) and ovariectomised marmosets did not differ significantly on any parameter of GnRH release. Overall, these results indicate that PPP can be used to reliably assess in vivo GnRH release in marmosets and will be a useful tool for future studies of reproductive neuroendocrinology in this small primate.
Sleep problems and daytime somnolence in a German population‐based sample of snoring school‐aged children
Authors: EITNER STEFFEN , URSCHITZ MICHAEL S. , GUENTHER ANKE , URSCHITZ‐DUPRAT PILAR M. , BOHNHORST BETTINA , SCHLAUD MARTIN , POETS CHRISTIAN F.
Published: February 2007

Habitual snoring is associated with daytime symptoms like tiredness and behavioral problems. Its association with sleep problems is unclear. We aimed to assess associations between habitual snoring and sleep problems in primary school children. The design was a population‐based cross‐sectional study with a nested cohort study. The setting was twenty‐seven primary schools in the city of Hannover, Germany. Habitual snoring and sleep problems were assessed in primary school children using an extended version of Gozal's sleep‐disordered breathing questionnaire (n = 1144). Approximately 1 year later, parents of children reported to snore habitually (n = 114) and an equal number of children who snored never or occasionally were given the Sleep Disturbance Scale for Children, a validated questionnaire for the assessment of pediatric sleep problems. Snoring status was re‐assessed using the initial questionnaire and children were then classified as long‐term habitual snorers or ex‐habitual snorers. An increasing prevalence of sleep problems was found with increasing snoring frequency for sleep‐onset delay, night awakenings, and nightmares. Long‐term habitual snorers were at significantly increased risk for sleep–wake transition disorders (e.g. rhythmic movements, hypnic jerks, sleeptalking, bruxism; odds ratio, 95% confidence interval: 12.0, 3.8–37.3), sleep hyperhidrosis (3.6, 1.2–10.8), disorders of arousal/nightmares (e.g. sleepwalking, sleep terrors, nightmares; 4.6, 1.3–15.6), and excessive somnolence (i.e. difficulty waking up, morning tiredness, daytime somnolence; 6.3, 2.2–17.8). Ex‐habitual snorers were at increased risk for sleep–wake transition disorders (4.4, 1.4–14.2). Habitual snoring was associated with several sleep problems in our study. Long‐term habitual snorers were more likely to have sleep problems than children who had stopped snoring spontaneously.
Absorption, psychological boundaries and attitude towards dreams as correlates of dream recall: two decades of research seen through a meta‐analysis
Authors: BEAULIEU‐PRÉVOST DOMINIC , ZADRA ANTONIO
Published: February 2007

Many studies have reported positive correlations between dream recall frequency (DRF) and measures of absorption, psychological boundaries and attitude towards dreams. A majority of these studies, however, have relied exclusively on retrospective measures of DRF even though daily dream logs are generally considered to be more direct and valid measures of DRF. The first goal of the present meta‐analysis was to evaluate the effect sizes of three variables (absorption, psychological boundaries and attitude towards dreams) as correlates of DRF. The second goal was to evaluate if these effect sizes varied as a function of how DRF was operationalized (i.e. retrospective measure versus dream log). Data from 24 studies were included in the analyses. For each of the three variables investigated, correlations with retrospective measures of DRF were of greater magnitude than those obtained with daily logs. These results indicate that scores on measures of absorption and psychological boundaries are not related to DRF per se, but rather to people's tendency to retrospectively underestimate or overestimate their DRF, while attitude towards dreams is related both to DRF per se and to people's retrospective estimation bias. Implications of these findings for dream research are discussed.
Mortality risk factors in sleep apnoea: a matched case–control study
Authors: LAVIE PERETZ , HERER PAULA , LAVIE LENA
Published: February 2007

Sleep apnoea syndrome was reported to be associated with increased mortality but it is not known if this association is independent of obesity and co‐morbidities. The present study investigated predictors of mortality in a large cohort of men with sleep apnoea using a case–control design. The study population consisted of 10 981 men diagnosed during 1991–2000 by whole‐night polysomnography with sleep apnoea; 331 men died prior to 1 September 2001, of whom 277 were matched by age, gender, site and time of study to patients who were alive in September 2001. Multivariate analysis revealed that all‐cause mortality was associated with chronic obstructive pulmonary disease (COPD) (odds ratio, OR: 7.07, 95% CI 2.75–18.16), chronic heart failure (CHF) (OR: 5.47, 95% CI 1.06–28.31), diabetes mellitus (DM) (OR: 3.30, 95% CI 1.51–7.20) and body mass index (BMI) (increase of 5 kg m−2, OR: 1.44, 95% CI: 1.04–1.99). Chronic upper airway problems were associated with survival (OR: 0.45, 95% CI 0.23–0.90). There were significant interactions between respiratory disturbance index and BMI and COPD. Mortality of patients younger than the median age (62 years) was associated with COPD, DM and an interaction between BMI and apnoea severity. Predictors of mortality for the older patients were COPD, CHF and DM. We conclude that all‐cause mortality in sleep apnoea is associated with co‐morbidities and obesity. Severity of sleep apnoea affects mortality by interacting with obesity and lung disease.
Extensive pollen dispersal in a bird‐pollinated shrub, Calothamnus quadrifidus, in a fragmented landscape
Authors: BYRNE M. , ELLIOTT C. P. , YATES C. , COATES D. J.
Published: February 2007

Pollen dispersal was investigated in six populations of Calothamnus quadrifidus, a bird‐pollinated shrub in the fragmented agricultural region of southern Western Australia. Paternity analysis using six microsatellite loci identified a pollen source within populations for 67% of seedlings, and the remainder were assumed to have arisen from pollen sources outside the populations. Outcrossing was variable, ranging from 5% to 82%, and long‐distance pollen dispersal was observed in all populations with up to 43% of pollen sourced from outside the populations over distances of up to 5 km. This extensive pollen immigration was positively associated with population size but not isolation. Comparison of two populations of similar size but different density showed greater internal pollination and less selfing in the denser population, suggesting an influence of density on pollinator behaviour. The study revealed extensive long‐distance pollen dispersal for C. quadrifidus within this fragmented agricultural landscape and highlighted the interaction between reserve populations and isolated road verge remnants in maintaining genetic connectivity at the landscape scale.
Distinct patterns of genetic variation in Pristionchus pacificus and Caenorhabditis elegans, two partially selfing nematodes with cosmopolitan distribution
Authors: ZAUNER HANS , MAYER WERNER E. , HERRMANN MATTHIAS , WELLER ANDREAS , ERWIG MIRJA , SOMMER RALF J.
Published: February 2007

Hermaphroditism has evolved several times independently in nematodes. The model organism Caenorhabditis elegans and Pristionchus pacificus are self‐fertile hermaphrodites with rare facultative males. Both species are members of different families: C. elegans belongs to the Rhabditidae and P. pacificus to the Diplogastridae. Also, both species differ in their ecology: C. elegans is a soil‐dwelling nematode that is often found in compost heaps. In contrast, field studies in Europe and North America indicate that Pristionchus nematodes are closely associated with scarab beetles. In C. elegans, several recent studies have found low genetic diversity and rare out‐crossing events. Little is known about diversity levels and population structure in free‐living hermaphroditic nematodes outside the genus Caenorhabditis. Taking a comparative approach, we analyse patterns of molecular diversity and linkage disequilibrium in 18 strains of P. pacificus from eight countries and four continents. Mitochondrial sequence data of P. pacificus isolates reveal a substantially higher genetic diversity on a global scale when compared to C. elegans. A mitochondrial‐derived hermaphrodite phylogeny shows little geographic structuring, indicating several worldwide dispersal events. Amplified fragment length polymorphism and single strand conformation polymorphism analyses demonstrate a high degree of genome‐wide linkage disequilibrium, which also extends to the mitochondrial genome. Together, these findings indicate distinct patterns of genetic variation of the two species. The low level of genetic diversity observed in C. elegans might reflect a recent human‐associated dispersal, whereas the P. pacificus diversity might reflect a long‐lasting and ongoing insect association. Thus, despite similar lifestyle characteristics in the laboratory, the reproductive mode of hermaphroditism with rare facultative males can result in distinct genetic variability patterns in different ecological settings.
Evaluating the performance of a multilocus Bayesian method for the estimation of migration rates
Authors: FAUBET PIERRE , WAPLES ROBIN S. , GAGGIOTTI OSCAR E.
Published: February 2007

Bayesian methods have become extremely popular in molecular ecology studies because they allow us to estimate demographic parameters of complex demographic scenarios using genetic data. Articles presenting new methods generally include sensitivity studies that evaluate their performance, but they tend to be limited and need to be followed by a more thorough evaluation. Here we evaluate the performance of a recent method, bayesass, which allows the estimation of recent migration rates among populations, as well as the inbreeding coefficient of each local population. We expand the simulation study of the original publication by considering multi‐allelic markers and scenarios with varying number of populations. We also investigate the effect of varying migration rates and FST more thoroughly in order to identify the region of parameter space where the method is and is not able to provide accurate estimates of migration rate. Results indicate that if the demographic history of the species being studied fits the assumptions of the inference model, and if genetic differentiation is not too low (FST ≥ 0.05), then the method can give fairly accurate estimates of migration rates even when they are fairly high (about 0.1). However, when the assumptions of the inference model are violated, accurate estimates are obtained only if migration rates are very low (m = 0.01) and genetic differentiation is high (FST ≥ 0.10). Our results also show that using posterior assignment probabilities as an indication of how much confidence we can place on the assignments is problematical since the posterior probability of assignment can be very high even when the individual assignments are very inaccurate.
Asexual and sexual hybrids betweenFundulus diaphanusandF. heteroclitusin the Canadian Atlantic region
Authors: HERNÁNDEZ CHÁVEZ CECILIA , TURGEON JULIE
Published: February 2007

Levels and origins of clonal diversity in asexual hybrid animals are critical to understanding how they can coexist with their sexual progenitor species. In this study, asexual gynogenetic hybrids betweenFundulus diaphanusandFundulus heteroclitusknown from two sites in Nova Scotia (Canada) were characterized using discriminant morphological traits, eight microsatellite loci, and mitochondrial DNA. Fifteen clonal genotypes were uncovered, all bearing the sameF. diaphanusmaternal haplotye. Each site harboured a different dominant clone along with several rarer clones that all appear to be of recent origin. Unexpectedly, highly introgressed sexually reproducing hybrids (0.25 > q > 0.75) were also detected. Sexual hybrids with maternal ascendance in either species were also found at three other sites in the Atlantic region. Based on a single meristic trait (scale counts), it is shown that asexual clones can be significantly more variable than populations of sexual parental species. Also, species are morphologically more alike when living in sympatry, suggesting that introgression may occur via sexual hybrids. Altogether, these results confirm and refine the available knowledge on this hybrid system, and indicate that hybridization is probably a more widespread phenomenon than suspected, with implications for the phenotypic variability of a widely used model species,F. heteroclitus.
Gene flow, effective population size and selection at major histocompatibility complex genes: brown trout in the Hardanger Fjord, Norway
Authors: HANSEN MICHAEL M. , SKAALA ØYSTEIN , JENSEN LASSE FAST , BEKKEVOLD DORTE , MENSBERG KAREN‐LISE D.
Published: February 2007

Brown trout populations in the Hardanger Fjord, Norway, have declined drastically due to increased exposure to salmon lice from salmonid aquaculture. We studied contemporary samples from seven populations and historical samples (1972 and 1983) from the two largest populations, one of which has declined drastically whereas the other remains stable. We analysed 11 microsatellite loci, including one tightly linked to the UBA gene of the major histocompatibility class I complex (MHC) and another locus linked to the TAP2A gene, also associated with MHC. The results revealed asymmetric gene flow from the two largest populations to the other, smaller populations. This has important conservation implications, and we predict that possible future population recoveries will be mediated primarily by the remaining large population. Tests for selection suggested diversifying selection at UBA, whereas evidence was inconclusive for TAP2A. There was no evidence for temporally fluctuating selection. We assessed the distribution of adaptive divergence among populations. The results showed the most pronounced footprints of selection between the two largest populations subject to the least immigration. We suggest that asymmetric gene flow has an important influence on adaptive divergence and constrains local adaptive responses in the smaller populations. Even though UBA alleles may not affect salmon louse resistance, the results bear evidence of adaptive divergence among populations at immune system genes. This suggests that similar genetic differences could exist at salmon louse resistance loci, thus rendering it a realistic scenario that differential population declines could reflect differences in adaptive variation.
A comparison of AFLPs and microsatellites to identify the population structure of brown trout (Salmo trutta L.) populations from Hardangervidda, Norway
Authors: SØNSTEBØ J. H. , BORGSTRØM R. , HEUN M.
Published: February 2007

A total of 495 fish from 11 Hardangervidda lakes were genotyped in order to compare amplified fragment length polymorphisms (AFLP) and microsatellites in terms of their capacity to infer population genetic structure. The 11 microsatellites used in this study gave a greater polymorphism information content and greater gene diversity, with an average of 14.8 alleles per locus, than the six AFLP primer combinations used. However, the AFLPs resulted in 178 polymorphic loci and a 3.1 times larger marker index (effective multiplex ratio multiplied with the gene diversity). Comparable population structuring, for example in terms of distinguishing fish from the different river systems, was obtained with both marker systems. An AFLP and microsatellite multilocus Bayesian assignment test with the structure program divided the fish into six groups largely concurrent with main branches on a population neighbour‐joining tree. Yet, the admixture status of individuals is mostly contradictory in the AFLP and the microsatellite analyses. The results are discussed concerning migration between lake populations.
Migration between continents: geographical structure and long‐distance gene flow in Porpidia flavicunda (lichen‐forming Ascomycota)
Authors: BUSCHBOM JUTTA
Published: February 2007

Historical and contemporary geographical distribution ranges with their associated gene flow patterns interact to produce the genetic diversity observed today. Often it is not possible to separate out the impacts of historical events, e.g. past fragmentation, and contemporary gene flow, e.g. long‐distance dispersal. Porpidia flavicunda is a lichen‐forming ascomycete occurring circumpolar in the boreal to arctic zones for which vegetation history suggests that its distribution pattern has stayed broadly the same over the past millennia. DNA‐sequence diversity in P. flavicunda can, thus, be expected to predominantly represent geographical population differentiation and its contemporary migration rates. The population sample consists of 110 specimens collected in Northern Québec, Baffin Island, Western Greenland and Northern Scandinavia. DNA‐sequence data sets of three nuclear gene fragments (LSU, RPB2 and β‐tubulin) were analysed for genetic diversity within, and differentiation between, geographical regions. Tests of population subdivision employing analyses of molecular variance and exact tests of haplotype frequency distributions showed significant structure between the geographical regions. However, the lack of fixed nucleotide polymorphisms and the wide sharing of identical haplotypes between geographical regions suggest recurrent long‐distance gene flow of propagules. Still, the means by which propagules are dispersed remain to be discovered. Inference of migration rates shows that in many cases a sufficiently high amount of migrants is exchanged between geographical regions to prevent drastic population differentiation through genetic drift. The observed haplotype distributions and migration rates point to a gene flow model of isolation by distance.
From the Apennines to the Alps: colonization genetics of the naturally expanding Italian wolf (Canis lupus) population
Authors: FABBRI ELENA , MIQUEL CHRISTIAN , LUCCHINI VITTORIO , SANTINI ALBERTO , CANIGLIA ROMOLO , DUCHAMP CHRISTOPHE , WEBER JEAN‐MARC , LEQUETTE BENOÎT , MARUCCO FRANCESCA , BOITANI LUIGI , FUMAGALLI LUCA , TABERLET PIERRE , RANDI ETTORE
Published: February 2007

Wolves in Italy strongly declined in the past and were confined south of the Alps since the turn of the last century, reduced in the 1970s to approximately 100 individuals surviving in two fragmented subpopulations in the central‐southern Apennines. The Italian wolves are presently expanding in the Apennines, and started to recolonize the western Alps in Italy, France and Switzerland about 16 years ago. In this study, we used a population genetic approach to elucidate some aspects of the wolf recolonization process. DNA extracted from 3068 tissue and scat samples collected in the Apennines (the source populations) and in the Alps (the colony), were genotyped at 12 microsatellite loci aiming to assess (i) the strength of the bottleneck and founder effects during the onset of colonization; (ii) the rates of gene flow between source and colony; and (iii) the minimum number of colonizers that are needed to explain the genetic variability observed in the colony. We identified a total of 435 distinct wolf genotypes, which showed that wolves in the Alps: (i) have significantly lower genetic diversity (heterozygosity, allelic richness, number of private alleles) than wolves in the Apennines; (ii) are genetically distinct using pairwiseFSTvalues, population assignment test and Bayesian clustering; (iii) are not in genetic equilibrium (significant bottleneck test). Spatial autocorrelations are significant among samples separated up toc. 230 km, roughly correspondent to the apparent gap in permanent wolf presence between the Alps and north Apennines. The estimated number of first‐generation migrants indicates that migration has been unidirectional and male‐biased, from the Apennines to the Alps, and that wolves in southern Italy did not contribute to the Alpine population. These results suggest that: (i) the Alps were colonized by a few long‐range migrating wolves originating in the north Apennine subpopulation; (ii) during the colonization process there has been a moderate bottleneck; and (iii) gene flow between sources and colonies was moderate (corresponding to 1.25–2.50 wolves per generation), despite high potential for dispersal. Bottleneck simulations showed that a total ofc. 8–16 effective founders are needed to explain the genetic diversity observed in the Alps. Levels of genetic diversity in the expanding Alpine wolf population, and the permanence of genetic structuring, will depend on the future rates of gene flow among distinct wolf subpopulation fragments.
The genetic structure of hawthorn‐infestingRhagoletis pomonellapopulations in Mexico: implications for sympatric host race formation
Authors: MICHEL ANDREW P. , RULL JUAN , ALUJA MARTIN , FEDER JEFFREY L.
Published: February 2007

The genetic origins of species may not all trace to the same time and place as the proximate cause(s) for population divergence. Moreover, inherent gene‐flow barriers separating populations may not all have evolved under the same geographical circumstances. These considerations have lead to a greater appreciation of the plurality of speciation: that one geographical mode for divergence may not always be sufficient to describe a speciation event. The apple maggot fly,Rhagoletis pomonella, a model system for sympatric speciation via host‐plant shifting, has been a surprising contributor to the concept of speciation mode plurality. Previous studies have suggested that past introgression of inversion polymorphism from a hawthorn‐fly population in the trans‐Mexican volcanic belt (EVTM) introduced diapause life‐history variation into a more northern fly population that subsequently contributed to sympatric host race formation and speciation in the United States (US). Here, we report results from a microsatellite survey implying (i) that volcanic activity in the eastern EVTM may have been responsible for the initial geographical isolation of the Mexican and northern hawthorn‐fly populationsc. 1.57 mya; and (ii) that flies in the Sierra Madre Oriental Mountains (SMO) likely served as a conduit for past gene flow from the EVTM into the US. Indeed, the microsatellite data suggest that the current US population may represent a range expansion from the northern SMO. We discuss the implications of these findings for sympatric race formation inRhagoletisand speciation theory.
Locating hybrid individuals in the red wolf(Canis rufus)experimental population area using a spatially targeted sampling strategy and faecal DNA genotyping
Authors: ADAMS JENNIFER R. , LUCASH CHRIS , SCHUTTE LESLIE , WAITS LISETTE P.
Published: February 2007

Hybridization with coyotes(Canis latrans)continues to threaten the recovery of endangered red wolves(Canis rufus)in North Carolina and requires the development of new strategies to detect and remove coyotes and hybrids. Here, we combine a spatially targeted faecal collection strategy with a previously published reference genotype data filtering method and a genetic test for coyote ancestry to screen portions of the red wolf experimental population area for the presence of nonred wolf canids. We also test the accuracy of our maximum‐likelihood assignment test for identifying hybrid individuals using eight microsatellite loci instead of the original 18 loci and compare its performance to the Bayesian approach implemented innewhybrids. We obtained faecal DNA genotypes for 89 samples, 73 of which were matched to 23 known individuals. The performance of two sampling strategies — comprehensive sweep and opportunistic spot‐check was evaluated. The opportunistic spot‐check sampling strategy required less effort than the comprehensive sweep sampling strategy but identified fewer individuals. Six hybrids or coyotes were detected and five of these individuals were subsequently captured and removed from the population. The accuracy and power of the genetic test for coyote ancestry is decreased when using eight loci; however, nonred wolf canids are identified with high frequency. This combination of molecular and traditional field‐based approaches has great potential for addressing the challenge of hybridization in other species and ecosystems.
Population differentiation and species cohesion in two closely related plants adapted to neotropical high‐altitude ‘inselbergs’,Alcantarea imperialisandAlcantarea geniculata(Bromeliaceae)
Authors: BARBARÁ T. , MARTINELLI G. , FAY M. F. , MAYO S. J. , LEXER C.
Published: February 2007

Isolated granitic rock outcrops or ‘inselbergs’ may provide a window into the molecular ecology and genetics of continental radiations under simplified conditions, in analogy to the use of oceanic islands in studies of species radiations. Patterns of variability and gene flow in inselberg species have never been thoroughly evaluated in comparison to related taxa with more continuous distribution ranges, or to other species in the same kingdom in general. We use nuclear microsatellites to study population differentiation and gene flow in two diploid, perennial plants adapted to high‐altitude neotropical inselbergs,Alcantarea imperialisandAlcantarea geniculata(Bromeliaceae). Population differentiation is pronounced in both taxa, especially inA. imperialis. Gene flow in this species is considerably lower than expected from the literature on plants in general and Bromeliaceae in particular, and too low to prevent differentiation due to drift (Nem < 1), unless selection coefficients/effect sizes of favourable alleles are great enough to maintain species cohesion. Low gene flow inA. imperialisindicates that the ability of pollinating bats to promote gene exchange between inselbergs is smaller than previously assumed. Population subdivision in one inselberg population ofA. imperialisappears to be associated with the presence of two colour morphs that differ in the coloration of rosettes and bracts. Our results indicate a high potential for inselbergs as venues for studies of the molecular ecology and genetics of continental radiations, such as the one that gave rise to the extraordinary diversity of adaptive strategies and phenotypes seen in Bromeliaceae.
Mylohyoid motor‐evoked potentials relate to swallowing function after chronic stroke dysphagia
Authors: Gallas S. , Moirot P. , Debono G. , Navarre I. , Denis P. , Marie J. P. , Verin E.
Published: February 2007

Abstract   This work aimed to study mylohyoid motor‐evoked potentials (MHMEPs) and examined if it is related to chronic stroke dysphagia. Conduction time (CT) and amplitudes of the right and left MHMEPs in response to focal cortical magnetic stimulations over affected and unaffected hemispheres were recorded in 16 stroke patients with aspiration (n = 9) or residue (n = 7) and compared with eight control patients. In control group, MHMEPs were present on ipsilateral and contralateral sides after stimulation of both hemispheres and permitted to determine a dominant hemisphere. In stroke patients, after stimulation of the affected hemisphere, ipsilateral MEPs had a longer CT and lower amplitudes in patients with aspiration compared with patients with residue or control patients (P < 0.05). Contralateral CT was not different between the three groups, but amplitudes were lower in patients with residue and aspiration than in control patients (P < 0.01). In the unaffected hemisphere, MHMEPs were present, and not different between the three groups for the ipsilateral side and amplitudes were decreased in contralateral side in patients with residue. In conclusion, MHMEP alterations of the affected hemisphere related to chronic stroke dysphagia severity and were closed to normal in the unaffected hemisphere.
Characterization of sensations induced by capsaicin in the upper gastrointestinal tract
Authors: Hammer J. , Vogelsang H.
Published: February 2007

Abstract  Intraluminal capsaicin induces perception in the jejunum, but chemosensitivity of proximal gastrointestinal regions is unclear. Our aim was to evaluate the quality of perception induced by intraluminal capsaicin in different regions of the upper gastrointestinal tract. Healthy volunteers received either an oral tube for distension and capsaicin perfusion of the mid‐duodenum or jejunum or swallowed a capsule containing 0.75 mg capsaicin powder. Graded questionnaires evaluated quality and severity of sensations during distensions, capsaicin infusion and 30 min after ingestion of capsaicin capsules respectively. Duodenal capsaicin induced sensations at lower doses than jejunal capsaicin (P < 0.05). Most prominent sensations evoked by capsaicin infusion were pressure, cramps, pain and nausea; nausea and warmth were more intense during capsaicin infusion than distension (P < 0.05,for the duodenum and jejunum), pain was more intense during distension (P < 0.05, duodenum only). Gastric ingestion of capsaicin capsules mainly induced sensations of pressure, heartburn and warmth. Capsaicin application into the upper gastrointestinal tract reproducibly induced upper abdominal sensation. Qualitative features distinguished chemically from mechanically induced sensations, but both sensitivity for chemical and mechanical stimulation decreased along the intestine. Activation of chemical pathways could be a useful human pain model activating nociceptors apart from mechanical stimulation.
The Upregulation of Expressed Proteins in HepG2 Cells Transfected by the Recombinant Plasmid‐containing HBx Gene
Authors: He Y. , Yang F. , Wang F. , Song S.‐X. , Li D.‐A. , Guo Y.‐J. , Sun S.‐H.
Published: February 2007

It is known that the hepatitis B virus X protein (HBx) plays a crucial role in the pathogenesis of HCC, but the exact functions and molecular mechanisms of HBx in HCC are not well understood. In the present study, HepG2 cell lines were cultured and transfected with pEGFP‐N1 and pEGFP‐N1‐X. Twenty‐four hours after transfection, cells were harvested and total RNA was extracted using TRIzol® reagent. The expression of HBx in HepG2 cell line was assayed by real‐time polymerase chain reaction and was detected by Western blotting. Moreover, proteomic analysis was performed for the HepG2‐pEGFP‐X cells and HepG2‐pEGFP control cells. The combination of 2DE and MALDI‐TOF‐MS/MS revealed that SEC13L1 (SEC13‐like 1 isoform b), PA28 alpha (proteasome activator REG alpha), serine–threonine kinase receptor‐associated protein (STRAP) and nm23/nucleoside diphosphate kinase (NME) were upregulated in HepG2‐pEGFP‐X cells. STRAP is known to be a WD40 domain‐containing protein, which interacts with TβR‐I and TβR‐II and negatively regulates TGF‐β signalling, was also found increased in human cancers. NME is known to be involved in the regulation of cancer cell progression and metastasis. These results would help the understanding of how HBx maintains tumorigenicity and progression of HCC.
The Effect of Gene Gun‐delivered pGM‐CSF on the Immunopathology of the Vaccinated Skin
Authors: Matthews K. , Rhind S. M. , Gossner A. G. , Dalziel R. G. , Hopkins J.
Published: February 2007

The aim of this study was to investigate the skin immunopathology of gene gun‐delivered plasmid‐encoded granulocyte‐macrophage colony‐stimulating factor (pGM‐CSF) and hence explore the possible mechanisms of its adjuvant activity. Using sheep as the experimental model, expressible pGM‐CSF was administered to the epidermis and the dermal/epidermal junction and its effects on the skin were assessed by histopathology, immunohistology and quantitative RT‐PCR for a range of pro‐inflammatory and immune response‐polarizing cytokines. Both functional and non‐functional plasmids caused an acute inflammatory response with the infiltration of neutrophils and micro‐abscess formation; however, the response to pGM‐CSF was more severe and was also associated with the accumulation of eosinophils, immature (CD1b−/CD172a−) dendritic cells and B cells. In terms of cytokine expression, an early TNF‐α response was stimulated by gene gun delivery of plasmid‐associated gold beads, which coincided with an immediate infiltration of neutrophils. However, only pGM‐CSF triggered the short‐lived expression of GM‐CSF (peaking at 4 h) and significant long‐term increases in both TNF‐α and IL‐1β. pGM‐CSF did not affect the expression of the immune response‐polarizing cytokines, IL‐10 and IL‐12.