bluuebunny/crossref_metadata_2025 huggingface dataset:
Traitement orthodontique des récessions parodontales : critères
de traitement
Authors: Delsol Laurent , Bousquet Philippe
Published: September 2011

La récession parodontale est un phénomène complexe. L’analyse de l’environnement dentaire
permet de prévoir la quantité du recouvrement en fonction de plusieurs éléments. La
présence et l’épaisseur de l’os alvéolaire, la hauteur et le type de la gencive attachée,
la position et l’angulation de la dent sont les points principaux à analyser. Si la dent
est en dehors de l’enveloppe parodontale, il y a un fort risque de récession. Les
techniques de recouvrement et d’épaississement sont bien codifiées. Il existe beaucoup de
récessions liées à la position de la dent. Ces récessions doivent être traitées par des
mouvements orthodontiques contrôlés. Dans certains cas, le traitement orthodontique peut,
à lui seul, améliorer l’environnement parodontal.
Influence of Long-term Statin use in Type 2 Diabetic Patients on Thyroid Nodularity in Iodine-sufficient Area
Authors: Chon M. , Suk J. , Oh K. , Kim K. , Kim Y. , Lee H. , Kim S. , Cho K. , Kim M. , Kim T.
Published: September 2011

Statins have marked beneficial effects on lipid profile, but also have pleiotropic actions. A previous study in an iodine-deficient area suggested that statin use is associated with reduced thyroid volume and nodularity. We performed this study to investigate how long-term statin use in type 2 diabetic patients affects thyroid nodularity in iodine-sufficient area.

We recruited euthyroid type 2 diabetic patients, receiving statin therapy continuously for at least 5 years (statin group) and, age and sex matched statin-naive type 2 diabetic patients (control group). Subjects with past history of cancer, thyroid disease or treatment with lithium or amiodarone; family history of thyroid cancer; palpable goiter or thyroid nodule, and/or positive thyroperoxidase antibody were excluded. The prevalence, number, and volume of thyroid nodules, size of thyroid were evaluated in all subjects by high resolution ultrasound.

Prevalence of non-palpable thyroid nodules of statin group (n=70) and control group (n=98) were 51 and 53% , respectively. There was no difference of prevalence, number, and volume of non-palpable thyroid nodules and size of thyroid between statin and control group. But, the patients aged between 60 and 65 years from statin group showed lower prevalence of non-palpable thyroid nodules than the patients with same age interval from control group (4 out of 12 patients, 33% , statin group; 19 out of 27 patients, 70% , control group; P=0.04).

Long-term statin use in elderly type 2 diabetic patients was associated with lesser prevalence of thyroid nodules in an iodine-sufficient area. Our data might support a possible antiproliferative effect of statins on thyroid in old type 2 diabetic patients. But, the effect was not as strong as that in an iodine-deficient area and further studies with enough numbers of subjects and revised design will be needed.
Circulating Obestatin Concentration is Lowered by Insulin in Rats
Authors: Huang J. , Zhang Y. , Yu S. , Gan X. , Su Y , Yuan J. , An R.
Published: September 2011

Circulating obestatin is lowered by food intake, but factors involved in obestatin regulation remain unclear. The aim of this study was to determine whether intravenous glucose or insulin infusion lowers obestatin. Rats were infused over 3 h with either A. saline (controls); B. dextrose to steady state blood glucose ~16.7 mM, or C. insulin 7.5 mU/kg.min, plus dextrose as needed to clamp to euglycemic basal concentrations. During 3 h of infusion, group B had significantly greater (P<0.01) glucose, 18.75±1.27 mM, than groups A (6.10±0.33 mM) or C (6.19±0.18 mM). Groups B and C had hyperinsulinemia at the end of the 3 h infusion (1.02±0.03 ng/ml, 1.07±0.02 ng/ml) compared with saline-infused (0.38±0.01 ng/ml, P<0.01). Obestatin concentrations were significantly reduced (P<0.01) in both hyperinsulinemic groups and (B=0.95±0.06 ng/ml; C=0.87±0.04 ng/ml) versus controls (1.56±0.13 ng/ml). These data suggest that insulin can decrease the plasma obestatin levels.
Lifestyle and Genetics in Obesity and type 2 Diabetes
Authors: Temelkova-Kurktschiev T. , Stefanov T.
Published: September 2011

Obesity and type 2 diabetes mellitus are multifactorial health threats caused by a complex interplay between genetic predisposition and the environment with dramatically increasing worldwide prevalence. The role of heritability in their etiology is well recognized, however, the numerous attempts made in order certain genetic variants determining individual susceptibility to be identified have had limited success, until recently. At present the advancements in human genetics and the utilization of the genome-wide association approach have led to the identification of over 20 genetic loci associated with, respectively obesity and type 2 diabetes. Most of the genes identified to date, however, have modest effect on disease risk suggesting that both diseases are unlikely to develop without the individual being exposed to obesity- and/or type 2 diabetes-promoting environment. Indeed, unhealthy lifestyle, characterized by physical inactivity and food overconsumption is an unequivocally established risk factor for obesity and type 2 diabetes. Numerous epidemiological studies and randomized controlled trials, on the other hand, have demonstrated that lifestyle modification is effective in obesity and type 2 diabetes prevention. Furthermore, gene-lifestyle interaction studies suggest that genetic susceptibility to obesity and type 2 diabetes may be partially or totally kept under control by healthy lifestyle or lifestyle modification and that lifestyle determines whether an individual is likely to develop the disease. Inherited factors, however, seem to influence individual response to a lifestyle intervention program and even the motivation for lifestyle change. Personalized interventions according to genotype may be, therefore, considered in the future. By then lifestyle modification targeting dietary change and increased physical activity may be recommended for successful obesity and type 2 diabetes prevention irrespectively of genetic susceptibility.
The Association of Cigarette Smoking with Serum TSH Concentration and Thyroperoxidase Antibody
Authors: Mehran L. , Amouzgar A. , Delshad H. , Azizi F.
Published: September 2011

Although several studies have found an association between tobacco smoking and thyroid disorders such as Graves’ disease, Graves’ ophtalmopathy, goiter and thyroid multi nodularity, the effect of smoking on thyroid function is controversial.

The aim of this study was to evaluate the association between smoking and serum TSH concentration and the presence of thyroperoxidase antibody (TPO Ab) in Tehranian adults.

In this cross sectional community based survey, 1 581 randomly selected subjects with no history of thyroid disorders were studied within the framework of Tehran Lipid and Glucose Study. Serum TSH and TPOAb were measured in a fasting serum sample. Weight and height were measured and BMI was calculated. Smokers were classified into ever and never smokers based on the declaration of participants.

Mean Ln TSH values in the ever smoker (0.36±0.82) was significantly lower than the never smoker (0.6±0.82) group (p<0.001) even after adjustment for age and BMI. The odds ratio for hypothyroidism (TSH>5.8) was 0.4 in the ever smoker group compared to the never one (odds ratio 0.4, 95% CI=0.2–0.8). The frequency of positive TPOAb in never smokers was significantly higher than ever smokers (%13.5 vs. % 6.7, p<0.001).

The results suggest that smoking is associated with decreased serum TSH concentrations, lower risk of hypothyroidism and possibly with a lower frequency of thyroid auto immunity.
The national Lifetimewool project: a journey in evaluation
Authors: Dart J. J. , Curnow M. , Behrendt R. , Kabore C. , Oldham C. M. , Rose I. J. , Thompson A. N.
Published: September 2011

The national Lifetimewool project commenced in 2001 and was funded until 2008. The objective of this project was to develop practical grazing management guidelines that would enable wool growers throughout Australia to increase lifetime production of wool per hectare from ewes. The project achieved its ambitious target of influencing 3000 producers to change their management of ewe flocks by adoption (or part thereof) of Lifetimewool messages and guidelines by 2008. The present paper focuses specifically on the evaluation work that was conducted on the project between 2003 and 2008. It is a noteworthy journey because it provides a case study of the effective implementation of an evaluation plan. The Lifetimewool project used ‘people-centred evaluation’ to help guide the creation of an internal evaluation plan. The six core principles followed were: participation; program logic, a people-centred focus; multiple lines of evidence; reflection and learning and a clearly documented and resourced evaluation plan. These principles were applied from the onset of the project. The Lifetimewool team used the evaluation findings to refine the initial design. Based on learnings from their evaluation journey, they created and modified the extension and communications components of the project. The present paper contends that the evaluation process itself enabled the project team to plan and adjust the course of the project through evidence-based reflection and that this helped ensure that the targets were achieved and demonstrated.
On-farm paddock-scale comparisons across southern Australia confirm that increasing the nutrition of Merino ewes improves their production and the lifetime performance of their progeny
Authors: Behrendt R. , van Burgel A. J. , Bailey A. , Barber P. , Curnow M. , Gordon D. J. , Edwards J. E. Hocking , Oldham C. M. , Thompson A. N.
Published: September 2011

Experiments conducted by Lifetimewool at plot-scale have shown that differences in the maternal liveweight during pregnancy and lactation (liveweight profiles) of individual Merino ewes influences their wool production and reproductive rate as well as the birthweight, survival, weaning weight and lifetime wool production of their lambs in a predictable manner. This study determined whether these impacts of nutrition of the ewe on ewe and progeny performance are measurable on commercial properties across southern Australia at a paddock-scale where ewes were aggregated into flocks with a greater spread of the date of conception and where the liveweight profile of the flocks were managed based on random samples of 100 ewes and liveweight was uncorrected for fleece weight or conceptus. Eighteen paddock-scale experiments at 15 sites were conducted in cooperation with wool producers across Victoria, Western Australia, New South Wales, South Australia, and Tasmania. Each co-operator joined up to 1000 mixed aged adult Merino ewes. The flock was scanned using ultrasound at Day 50 from the start of joining to identify those ewes that conceived during the first 21 days of joining. These ewes were then split at random into two treatments and fed to achieve a target difference in liveweight of 10 kg or ~1 condition score/fat score at lambing. The production of ewes during their year of pregnancy and following their next joining was measured as was the performance of their progeny up to their third shearing. Only the 13 paddock-scale experiments that achieved a difference in liveweight profile at lambing of at least 4 kg were included in the final analysis. In these 13 experiments, increasing the nutrition of Merino ewes during pregnancy clearly increased the clean fleece weight and fibre diameter in ewes and the survival and lifetime wool production of their lambs. In most cases the size of the effect was not significantly different to that predicted by the relationship derived using individual liveweight profiles in the plot-scale experiments. This confirms that managing average ewe liveweight or condition score/fat score profile through better nutrition will lead to predictable increases in the performance of ewes and their progeny performance under commercial conditions and validates the use of the plot-scale relationships in economic analyses.
Evaluation of the impact of Lifetimewool on sheep producers
Authors: Jones A. , van Burgel A. J. , Behrendt R. , Curnow M. , Gordon D. J. , Oldham C. M. , Rose I. J. , Thompson A. N.
Published: September 2011

Lifetimewool was a national project that began in 2001 to develop profitable ewe feeding and management guidelines for wool producers across southern Australia. By 2005, the project included communication and adoption activities. Rigorous communication, adoption and evaluation plans were used to maintain focus on its objectives and to measure impacts. Evaluation was an integral part of the project’s development and allowed the project to gain a clear idea of its impact. The project aimed to influence at least 3000 producers nationally to change the management of their ewe flock by the adoption (or part thereof) of Lifetimewool messages and guidelines. More specifically, the project aimed to ‘cross the chasm’ and target producers that were deemed to be in the ‘early adopter’ and the ‘early majority’ segments. The project surveyed sheep producers, sheep industry consultants and sheep industry extension practitioners at the beginning and end of the project to gauge the change in knowledge, attitudes, skills and aspirations of wool producers over the life of the project. Results from the survey of sheep producers in 2008 indicate that the project achieved its aim. About 12% (~3000) of sheep producers nationally have changed practice due to information received from Lifetimewool since 2005. Many other producers have been affected through their increase in knowledge, belief and skills, and market segmentation of the audience shows that the project was successful in ‘crossing the chasm’. The strategies employed by the project to initiate change (i.e. using private consultants and extension professionals as a pathway to adoption, and involving producers, consultants and extension professionals in the development of the Lifetimewool key messages and tools) were validated. The survey results and analysis provided baseline data for future livestock management projects to build on producers’ progress towards practice change. The present paper looks at how the Lifetimewool’s evaluation plan provided a focus for and demonstrated meeting its objectives. In doing so, this paper also seeks to better understand the adoption process.
Repressor transcription factor 7-like 1 promotes adipogenic competency in precursor cells
Authors: Cristancho Ana G. , Schupp Michael , Lefterova Martina I. , Cao Shengya , Cohen Daniel M. , Chen Christopher S. , Steger David J. , Lazar Mitchell A.
Published: September 2011

The identification of factors that define adipocyte precursor potential has important implications for obesity. Preadipocytes are fibroblastoid cells committed to becoming round lipid-laden adipocytes. In vitro, this differentiation process is facilitated by confluency, followed by adipogenic stimuli. During adipogenesis, a large number of cytostructural genes are repressed before adipocyte gene induction. Here we report that the transcriptional repressor transcription factor 7-like 1 (TCF7L1) binds and directly regulates the expression of cell structure genes. Depletion of TCF7L1 inhibits differentiation, because TCF7L1 indirectly induces the adipogenic transcription factor peroxisome proliferator-activated receptor γ in a manner that can be replaced by inhibition of myosin II activity. TCF7L1 is induced by cell contact in adipogenic cell lines, and ectopic expression of TCF7L1 alleviates the confluency requirement for adipocytic differentiation of precursor cells. In contrast, TCF7L1 is not induced during confluency of non-adipogenic fibroblasts, and, remarkably, forced expression of TCF7L1 is sufficient to commit non-adipogenic fibroblasts to an adipogenic fate. These results establish TCF7L1 as a transcriptional hub coordinating cell–cell contact with the transcriptional repression required for adipogenic competency.
Structural flexibility of the Gαs α-helical domain in the β
2
-adrenoceptor Gs complex
Authors: Westfield Gerwin H. , Rasmussen Søren G. F. , Su Min , Dutta Somnath , DeVree Brian T. , Chung Ka Young , Calinski Diane , Velez-Ruiz Gisselle , Oleskie Austin N. , Pardon Els , Chae Pil Seok , Liu Tong , Li Sheng , Woods Virgil L. , Steyaert Jan , Kobilka Brian K. , Sunahara Roger K. , Skiniotis Georgios
Published: September 2011

The active-state complex between an agonist-bound receptor and a guanine nucleotide-free G protein represents the fundamental signaling assembly for the majority of hormone and neurotransmitter signaling. We applied single-particle electron microscopy (EM) analysis to examine the architecture of agonist-occupied β
2
-adrenoceptor (β
2
AR) in complex with the heterotrimeric G protein Gs (Gαsβγ). EM 2D averages and 3D reconstructions of the detergent-solubilized complex reveal an overall architecture that is in very good agreement with the crystal structure of the active-state ternary complex. Strikingly however, the α-helical domain of Gαs appears highly flexible in the absence of nucleotide. In contrast, the presence of the pyrophosphate mimic foscarnet (phosphonoformate), and also the presence of GDP, favor the stabilization of the α-helical domain on the Ras-like domain of Gαs. Molecular modeling of the α-helical domain in the 3D EM maps suggests that in its stabilized form it assumes a conformation reminiscent to the one observed in the crystal structure of Gαs-GTPγS. These data argue that the α-helical domain undergoes a nucleotide-dependent transition from a flexible to a conformationally stabilized state.
Relative risk regression: reliable and flexible methods for log-binomial models
Authors: Marschner Ian C. , Gillett Alexandra C.
Published: September 2011

Relative risks (RRs) are generally considered preferable to odds ratios in prospective studies. However, unlike logistic regression for odds ratios, the standard log-binomial model for RR regression does not respect the natural parameter constraints and is therefore often subject to numerical instability. In this paper, we develop a reliable and flexible method for fitting log-binomial models. We use an Expectation–Maximization (EM) algorithm where the multiplicative event probability is viewed as the joint probability for a collection of latent binary outcomes. This gives a simple iterative scheme that provides stable convergence to the maximum likelihood estimate. In addition to reliability, the method offers some flexible generalizations, including models with unspecified isotonic regression functions. We examine the method's performance using simulations and data analyses of the age-specific RR of mortality following heart attack. These analyses demonstrate the potential for numerical instability in RR regression and show how this can be overcome using the proposed approach. Source code to implement the method in R is provided as supplementary material available at Biostatistics online.
Virulence of Bursaphelenchus xylophilus Isolated from Naturally Infested Pine Forests to Five Resistant Families of Pinus thunbergii
Authors: Akiba Mitsuteru , Ishihara Makoto , Sahashi Norio , Nakamura Katsunori , Ohira Mineko , Toda Tadao
Published: September 2011

Pine wilt disease is one of the most serious epidemic tree diseases in Japan, and resistant pine trees have been developed through a breeding program. To evaluate resistance of resistant families of Japanese black pine, Pinus thunbergii, to the pinewood nematode, Bursaphelenchus xylophilus, isolated from the field, and to determine whether differentiation of pathogenicity to resistant pine families appears in the nematode isolates, seedlings of five resistant pine families were inoculated with 25 nematode isolates. Disease incidence 18 weeks after inoculation was significantly different among nematode isolates and among pine families but there was no interaction effect between nematode isolate and pine family. This indicates that nematode isolates did not have differential host specificity to resistant families of P. thunbergii. Isolate Shimabara, a test isolate of the breeding program, showed the same degree of virulence as the highly virulent isolates frequently used in experiments. However, more virulent isolates than Shimabara were found among the isolates collected from natural pine forest. This indicated that B. xylophilus populations with higher virulence than Shimabara exist in the natural population. These findings are important in development of more efficient breeding procedures for resistant pine trees.
Daily torpor is associated with telomere length change over winter in Djungarian hamsters
Authors: Turbill Christopher , Smith Steve , Deimel Caroline , Ruf Thomas
Published: September 2011

Ageing can progress at different rates according to an individual's physiological state. Natural hypothermia, including torpor and hibernation, is a common adaptation of small mammals to survive intermittent or seasonal declines in environmental conditions. In addition to allowing energy savings, hypothermia and torpor have been associated with retarded ageing and increased longevity. We tested the hypothesis that torpor use slows ageing by measuring changes in the relative telomere length (RTL) of Djungarian hamsters,
Phodopus sungorus
, a highly seasonal rodent using spontaneous daily torpor, over 180 days of exposure to a short-day photoperiod and warm (approx. 20°C) or cold (approx. 9°C) air temperatures. Multi-model inference showed that change in RTL within individuals was best explained by positive effects of frequency of torpor use, particularly at low body temperatures, as well as the change in body mass and initial RTL. Telomere dynamics have been linked to future survival and proposed as an index of rates of biological ageing. Our results therefore support the hypothesis that daily torpor is associated with physiological changes that increase somatic maintenance and slow the processes of ageing.
Is the true ‘wisdom of the crowd’ to copy successful individuals?
Authors: King Andrew J. , Cheng Lawrence , Starke Sandra D. , Myatt Julia P.
Published: September 2011

Diversity of expertise at an individual level can increase intelligence at a collective level—a type of swarm intelligence (SI) popularly known as the ‘wisdom of the crowd’. However, this requires independent estimates (rare in the real world owing to the availability of public information) and contradicts people's bias for copying successful individuals. To explain these inconsistencies, 429 people took part in a ‘guess the number of sweets’ exercise. Guesses made with no public information were diverse, resulting in highly accurate SI. Individuals with access to the previous guess, mean guess or a randomly chosen guess, tended to over-estimate the number of sweets and this undermined SI. However, when people were provided with the current best guess, this prevented very large (inaccurate) guesses, resulting in convergence of guesses towards the true value and accurate SI across a range of group sizes. Thus, contrary to previous work, we show that social influence need not undermine SI, especially where individual decisions are made sequentially and then aggregated. Furthermore, we offer an explanation for why people have a bias to recruit and follow experts in team settings: copying successful individuals can enable accuracy at both the individual and group level, even at small group sizes.
Cell wall structure and formation of maturing fibres of moso bamboo (
Phyllostachys pubescens
) increase buckling resistance
Authors: Wang Xiaoqing , Ren Haiqing , Zhang Bo , Fei Benhua , Burgert Ingo
Published: September 2011

The mechanical stability of the culms of monocotyledonous bamboos is highly attributed to the proper embedding of the stiff fibre caps of the vascular bundles into the soft parenchymatous matrix. Owing to lack of a vascular cambium, bamboos show no secondary thickening growth that impedes geometrical adaptations to mechanical loads and increases the necessity of structural optimization at the material level. Here, we investigate the fine structure and mechanical properties of fibres within a maturing vascular bundle of moso bamboo,
Phyllostachys pubescens
, with a high spatial resolution. The fibre cell walls were found to show almost axially oriented cellulose fibrils, and the stiffness and hardness of the central part of the cell wall remained basically consistent for the fibres at different regions across the fibre cap. A stiffness gradient across the fibre cap is developed by differential cell wall thickening which affects tissue density and thereby axial tissue stiffness in the different regions of the cap. The almost axially oriented cellulose fibrils in the fibre walls maximize the longitudinal elastic modulus of the fibres and their lignification increases the transverse rigidity. This is interpreted as a structural and mechanical optimization that contributes to the high buckling resistance of the slender bamboo culms.
Social laughter is correlated with an elevated pain threshold
Authors: Dunbar R. I. M. , Baron Rebecca , Frangou Anna , Pearce Eiluned , van Leeuwen Edwin J. C. , Stow Julie , Partridge Giselle , MacDonald Ian , Barra Vincent , van Vugt Mark
Published: September 2011

Although laughter forms an important part of human non-verbal communication, it has received rather less attention than it deserves in both the experimental and the observational literatures. Relaxed social (Duchenne) laughter is associated with feelings of wellbeing and heightened affect, a proximate explanation for which might be the release of endorphins. We tested this hypothesis in a series of six experimental studies in both the laboratory (watching videos) and naturalistic contexts (watching stage performances), using change in pain threshold as an assay for endorphin release. The results show that pain thresholds are significantly higher after laughter than in the control condition. This pain-tolerance effect is due to laughter itself and not simply due to a change in positive affect. We suggest that laughter, through an endorphin-mediated opiate effect, may play a crucial role in social bonding.
Grandparental investment and reproductive decisions in the longitudinal 1970 British cohort study
Authors: Waynforth David
Published: September 2011

There has been a recent increase in interest among evolutionary researchers in the hypothesis that humans evolved as cooperative breeders, using extended family support to help decrease offspring mortality and increase the number of children that can be successfully reared. In this study, data drawn from the 1970 longitudinal British cohort study were analysed to determine whether extended family support encourages fertility in contemporary Britain. The results showed that at age 30, reported frequency that participants saw their own parents (but not in-laws) and the closeness of the bond between the participant and their own parents were associated with an increased likelihood of having a child between ages 30 and 34. Financial help and reported grandparental childcare were not significantly positively associated with births from age 30 to 34. Men's income was positively associated with likelihood of birth, whereas women's income increased likelihood of birth only for working women with at least one child. While it was predicted that grandparental financial and childcare help would increase the likelihood of reproduction by lowering the cost to the parent of having a child, it appears that the mere physical presence of supportive parents rather than their financial or childcare help encouraged reproduction in the 1970 British birth cohort sample.
Twofold cost of reproduction: an increase in parental effort leads to higher malarial parasitaemia and to a decrease in resistance to oxidative stress
Authors: Christe Philippe , Glaizot Olivier , Strepparava Nicole , Devevey Godefroy , Fumagalli Luca
Published: September 2011

Parental effort is usually associated with high metabolism that could lead to an increase in the production of reactive oxidative species giving rise to oxidative stress. Since many antioxidants involved in the resistance to oxidative stress can also enhance immune function, an increase in parental effort may diminish the level of antioxidants otherwise involved in parasite resistance. In the present study, we performed brood size manipulation in a population of great tits (
Parus major
) to create different levels of parental effort. We measured resistance to oxidative stress and used a newly developed quantitative PCR assay to quantify malarial parasitaemia. We found that males with an enlarged brood had significantly higher level of malarial parasites and lower red blood cell resistance to free radicals than males rearing control and reduced broods. Brood size manipulation did not affect female parasitaemia, although females with an enlarged brood had lower red blood cell resistance than females with control and reduced broods. However, for both sexes, there was no relationship between the level of parasitaemia and resistance to oxidative stress, suggesting a twofold cost of reproduction. Our results thus suggest the presence of two proximate and independent mechanisms for the well-documented trade-off between current reproductive effort and parental survival.
Cell Fate in the Arabidopsis Root Epidermis Is Determined by Competition between WEREWOLF and CAPRICE
Authors: Song Sang-Kee , Ryu Kook Hui , Kang Yeon Hee , Song Jae Hyo , Cho Young-Hee , Yoo Sang-Dong , Schiefelbein John , Lee Myeong Min
Published: September 2011

The root hair and nonhair cells in the Arabidopsis (Arabidopsis thaliana) root epidermis are specified by a suite of transcriptional regulators. Two of these are WEREWOLF (WER) and CAPRICE (CPC), which encode MYB transcription factors that are required for promoting the nonhair cell fate and the hair cell fate, respectively. However, the precise function and relationship between these transcriptional regulators have not been fully defined experimentally. Here, we examine these issues by misexpressing the WER gene using the GAL4-upstream activation sequence transactivation system. We find that WER overexpression in the Arabidopsis root tip is sufficient to cause epidermal cells to adopt the nonhair cell fate through direct induction of GLABRA2 (GL2) gene expression. We also show that GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), two closely related bHLH proteins, are required for the action of the overexpressed WER and that WER interacts with these bHLHs in plant cells. Furthermore, we find that CPC suppresses the WER overexpression phenotype quantitatively. These results show that WER acts together with GL3/EGL3 to induce GL2 expression and that WER and CPC compete with one another to define cell fates in the Arabidopsis root epidermis.
Condensin II Alleviates DNA Damage and Is Essential for Tolerance of Boron Overload Stress in Arabidopsis
Authors: Sakamoto Takuya , Inui Yayoi Tsujimoto , Uraguchi Shimpei , Yoshizumi Takeshi , Matsunaga Sachihiro , Mastui Minami , Umeda Masaaki , Fukui Kiichi , Fujiwara Toru
Published: September 2011

Although excess boron (B) is known to negatively affect plant growth, its molecular mechanism of toxicity is unknown. We previously isolated two Arabidopsis thaliana mutants, hypersensitive to excess B (heb1-1 and heb2-1). In this study, we found that HEB1 and HEB2 encode the CAP-G2 and CAP-H2 subunits, respectively, of the condensin II protein complex, which functions in the maintenance of chromosome structure. Growth of Arabidopsis seedlings in medium containing excess B induced expression of condensin II subunit genes. Simultaneous treatment with zeocin, which induces DNA double-strand breaks (DSBs), and aphidicolin, which blocks DNA replication, mimicked the effect of excess B on root growth in the heb mutants. Both excess B and the heb mutations upregulated DSBs and DSB-inducible gene transcription, suggesting that DSBs are a cause of B toxicity and that condensin II reduces the incidence of DSBs. The Arabidopsis T-DNA insertion mutant atr-2, which is sensitive to replication-blocking reagents, was also sensitive to excess B. Taken together, these data suggest that the B toxicity mechanism in plants involves DSBs and possibly replication blocks and that plant condensin II plays a role in DNA damage repair or in protecting the genome from certain genotoxic stressors, particularly excess B.
Biosynthesis and Defensive Function of N
Δ-Acetylornithine, a Jasmonate-Induced Arabidopsis Metabolite
Authors: Adio Adewale M. , Casteel Clare L. , De Vos Martin , Kim Jae Hak , Joshi Vijay , Li Baohua , Juéry Caroline , Daron Josquin , Kliebenstein Daniel J. , Jander Georg
Published: September 2011

Since research on plant interactions with herbivores and pathogens is often constrained by the analysis of already known compounds, there is a need to identify new defense-related plant metabolites. The uncommon nonprotein amino acid N  Δ-acetylornithine was discovered in a targeted search for Arabidopsis thaliana metabolites that are strongly induced by the phytohormone methyl jasmonate (MeJA). Stable isotope labeling experiments show that, after MeJA elicitation, Arg, Pro, and Glu are converted to Orn, which is acetylated by NATA1 to produce N  Δ-acetylornithine. MeJA-induced N  Δ-acetylornithine accumulation occurs in all tested Arabidopsis accessions, other Arabidopsis species, Capsella rubella, and Boechera stricta, but not in less closely related Brassicaceae. Both insect feeding and Pseudomonas syringae infection increase NATA1 expression and N  Δ-acetylornithine accumulation. NATA1 transient expression in Nicotiana tabacum and the addition of N  Δ-acetylornithine to an artificial diet both decrease Myzus persicae (green peach aphid) reproduction, suggesting a direct toxic or deterrent effect. However, since broad metabolic changes that are induced by MeJA in wild-type Arabidopsis are attenuated in a nata1 mutant strain, there may also be indirect effects on herbivores and pathogens. In the case of P. syringae, growth on a nata1 mutant is reduced compared with wild-type Arabidopsis, but growth in vitro is unaffected by N  Δ-acetylornithine addition.
Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure
Authors: Korecki P. , Tolkiehn M. , Dąbrowski K. M. , Novikov D. V.
Published: September 2011

Projections of the atomic structure around Nb atoms in a LiNbO3single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using NbKfluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples.
Mental preparation during pregnancy in women with substance addiction: a qualitative interview‐study
Authors: Söderström Kerstin
Published: September 2011

The interplay between pregnancy and addiction is usually studied quantitatively, and the focus is often on the adverse effects of intrauterine substance exposure. This study explores the perspective of the mothers‐to‐be by examining the subjective experience of pregnancy in substance‐addicted women. Fourteen women in family treatment for substance use disorder participated in eight focus groups. The data were analysed according to interpretative phenomenological analysis. The findings show that recognition of pregnancy was distorted and delayed, and strong feelings of ambivalence and guilt persisted throughout pregnancy, along with hope for change. Addiction and an intense preoccupation with external expectations are seen as a threat to intrauterine attachment and mental preparation for the caregiving role. Interventions must take into account the specific ways in which addiction influences the psychological processes of pregnancy; specifically, providing adequate social support and security should be considered.
Trait‐mediated effects of predation across life‐history stages in container mosquitoes
Authors: COSTANZO KATIE S. , MUTURI EPHANTUS J. , ALTO BARRY W.
Published: September 2011

1. It was determined if the predatory midgeCorethrella appendiculataGrabham imposes a fitness cost in a native mosquito,Ochlerotatus triseriatusSay, and an invasive mosquito,Aedes albopictusSkuse. The hypothesis that decreased activity of immature prey in the presence of predator cues is associated with life history costs through all life cycle stages was tested.

2. In experiment 1, individual larvae ofO. triseriatusorA. albopictuswere raised in the presence or absence of predation cues at two resource levels. Prey were video recorded to detect behavioural responses and to measure development time, size at emergence, and adult longevity. In experiment 2, prey populations were reared in similar environments and the frequency of predator cue additions was varied.

3. OnlyO. triseriatusreduced its activity in the presence of predation cues. Predation cues were associated with longer immature development times and shorter adult life spans inO. triseriatus,whereas inA. albopictus, the cues were associated with a larger size of emerging adults.

4. In the present study, it was found that behavioural modifications during the larval stage can affect mosquitoes through multiple stages of their complex life cycle. The species‐specific behavioural differences are probably attributable to the longer evolutionary historyO. triseriatushas with predators, relative to the invasiveA. albopictus.
Community‐wide impact of an exotic aphid on introduced tall goldenrod
Authors: ANDO YOSHINO , UTSUMI SHUNSUKE , OHGUSHI TAKAYUKI
Published: September 2011

1. The aphid Uroleucon nigrotuberculatum Olive, which is specialised to the tall goldenrod, Solidago altissima L., in its native range, has become a dominant species on the introduced tall goldenrod in Japan. How this exotic aphid influenced arthropod communities on the introduced tall goldenrod in aphid‐present (spring) and aphid‐absent (autumn) seasons was examined, using an aphid removal experiment.

2. In spring, aphid presence increased ant abundance because aphid honeydew attracted foraging ant workers. A significant negative correlation was found between the numbers of ants and herbivorous insects other than aphids on the aphid‐exposed plants, but no significant correlation was detected on the aphid‐free plants. Thus, the aphid presence was likely to decrease the abundance of co‐occurring herbivorous insects through removal behaviour of the aphid‐tending ants. There were no significant differences in plant traits between the aphid‐exposed and aphid‐free plants.

3. In autumn, the numbers of lateral shoots and leaves, and the leaf nitrogen content were increased in response to the aphid infestation in spring. Because of the improvement of plant traits by aphid feeding, the abundance of leaf chewers increased on aphid‐exposed plants. In contrast, the abundance of sap feeders decreased on the aphid‐exposed plants. In particular, the dominant scale insect among sap feeders, Parasaissetia nigra Nietner, decreased, followed by a decrease in the abundance of ants attending P. nigra. Thus, aphid feeding may have attenuated the negative impacts of the tending ants on leaf chewers.

4. Aphid presence did not change herbivore species richness but changed the relative density of dominant herbivores, resulting in community‐wide effects on co‐occurring herbivores through ant‐mediated indirect effects, and on temporally separated herbivores through plant‐ and ant‐mediated indirect effects. The aphid also altered predator community composition by increasing and decreasing the relative abundance of aphid‐tending ants in the spring and autumn, respectively.
Responses of insect herbivores to sharing a host plant with a hemiparasite: impacts on preference and performance differ with feeding guild
Authors: EWALD NAOMI C. , JOHN ELIZABETH A. , HARTLEY SUSAN E.
Published: September 2011

1. Root hemiparasites are common components of many ecosystems and can affect both the biomass and the nutritional quality of the plants they infect. The consequences of these modifications for the preference and performance of three herbivore feeding guilds sharing a host with the hemi‐parasite were examined.

2. It was predicted that as the hemiparasite increased in biomass its impact on the host would increase, as would the indirect impacts on the herbivores. It was also predicted that herbivores from different feeding guilds would respond differently to the presence of the hemiparasite, reflecting the extent to which they utilise resources disrupted by the parasite and hence are in competition with it.

3. The preference and performance of phloem‐feeding aphids, xylem‐feeding spittle bugs, and leaf‐feeding grasshoppers were measured on the host grass species, Holcus lanatus L. (Poaceae), with and without attachment from the hemi‐parasite, Rhinanthus minor L. (Orobanchaceae).

4. The effects of R. minor on the host were dependent on the hemiparasite's stage of growth, being most pronounced when it was at peak biomass. At this stage it caused a significant reduction in the biomass, water content, and total nitrogen content of the host plants.

5. Overall, herbivores benefited from, or preferred, shared host plants more than uninfected plants. The aphid benefited from sharing a host with R. minor, showing increased population growth on, and preference for, parasitised plants. The spittle bug also showed a preference for parasitised plants. The grasshopper, Chorthippus brunneus Thunberg (Orthoptera: Acrididae), did not show a preference for, or a performance response to, parasitised hosts, but it consumed significantly more plant material when caged on parasitised plants.

6. These data support the prediction that invertebrate herbivores responded to changes in host plant traits driven by the hemiparasite, and strongly suggest that these indirect interactions could impact on population and community processes within natural communities.
Oviposition preference ofLycaena salustiusfor, and larval performance on, a novel host plant: an example of ecological fitting
Authors: GILLESPIE MARK , WRATTEN STEVE D.
Published: September 2011

1. ‘Ecological fitting’ is the process whereby the suites of traits an organism carries from previous evolutionary relationships are used to enable colonisation of novel environments or resources.

2. The concept has much explanatory power in studies of novel host associations, particularly when data suggest a deviation from optimal foraging theory, but is often overlooked in studies of herbivore host selection behaviour in favour of evolutionary hypotheses.

3. In the present study, the concept was used to explain the unusual host selection behaviour of the New Zealand endemic oligophagous butterflyLycaena salustiusFabricius, the larvae of which feed on endemic Polygonaceae species and the introduced and closely relatedFagopyrum esculentumMoench.

4. In field cage oviposition choice assays involving only endemic plants, females preferred to oviposit on the rareMuehlenbeckia astoniiPetrie. However, the novel hostF. esculentumwas overwhelmingly preferred in an additional greenhouse assay. In larval no‐choice performance assays, fitness indicators were variable for the novel host.

5. This imperfect relationship between oviposition preference and larval performance is discussed as a possible example of ecological fitting and highlights the potential use of the concept as an explanatory tool in novel host selection behaviour studies.
Can infection by eugregarine parasites mediate species coexistence in Calopteryx damselflies?
Authors: ILVONEN SINI , ILVONEN JAAKKO J. , KAUNISTO KARI M. , KRAMS INDRIKIS , SUHONEN JUKKA
Published: September 2011

1. Parasitism may be an important factor determining the coexistence of closely related species. Although host–parasite interactions can affect the ecology and distribution of the host species, virtually nothing is known about how other interspecific interactions affecting the host, such as competition or predation, relate to the parasite burden of the host.

2. We studied parasite‐mediated competition between two closely related Calopteryx damselflies, C. virgo L. and C. splendens Harris. We investigated a total of 31 populations, including 18 allopatric and 13 sympatric populations. We measured the occurrence of gut parasites, eugregarines.

3. We found that the prevalence of gregarines was higher in C. virgo than in C. splendens. On average, more than half of the C. virgo individuals were infected by eugregarines both in allopatric and sympatric populations. However, hardly any allopatric C. splendens populations had gregarines, but most of sympatric populations had infected individuals.

4. According to our results, co‐existence of the host species affects the likelihood of the subordinate species showing higher levels of parasitism. Interspecific aggression, lower species genetic heterozygosity, and the difference in host species immunity are proposed as possible explanations for greater parasite burdens in the inferior species at sympatric sites.
Bacterial symbionts as mediators of ecologically important traits of insect hosts
Authors: FELDHAAR HEIKE
Published: September 2011

1. Bacterial symbionts play a prominent role in insect nutritional ecology by aiding in digestion of food or providing nutrients that are limited or lacking in the diet. Thereby, endosymbionts open niches to their insect host that would otherwise be unavailable.

2. Currently, several other ecologically relevant traits mediated by endosymbionts are being investigated, including enhanced parasite resistance, enhanced heat tolerance, and influences on insect–plant interactions such as manipulation of plant physiology to the benefit of the insect.

3. Traits mediated by endosymbionts are often identified by correlative studies where traits are found to be altered in the presence of a particular symbiont. Recent developments in genomic tools offer the opportunity for studying the impact of bacteria–insect symbioses under natural conditions in a population and community ecology context. In vivo experiments specifically testing putative functions of endosymbionts in parallel to population‐level studies on the prevalence of endosymbionts allow disentangling host versus symbiont contribution to phenotypic variability observed in individuals. Effects of symbionts on host phenotype are often large and relevant to host fitness, e.g. by significantly enhancing survival or fecundity in a context‐dependent manner.

4. Predominantly vertically transmitted endosymbionts contribute to the heritable genetic variation present in a host species. Phenotypic variation on which selection can act may be due to differences either among host genomes, symbiont genomes, or genotype × genotype interactions. Therefore the holobiont, i.e. the host including all symbionts, should be regarded as the unit of selection as the association between host and symbionts may affect the fitness of the holobiont depending on the environment.