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21.
The biosynthesis of dehydrotremetone in Eupatorium rugosum has been investigated by feeding radioactive precursors to intact plants. The carbon atoms of acetate-[1-14C] and acetate-[2-14C] were identified in dehydrotremetone by degradation of the molecule. From the pattern of labeling it was concluded that the acetophenone moiety was derived from acetate via the polyacetate pathway. From the incorporation of mevalonate it appeared that the furan ring and its side chain were formed from an isoprenoid compound. Potential aromatic intermediates were chemically synthesized and also fed to plants but only tremetone was found to be efficiently incorporated into dehydrotremetone. Neither 4-hydroxyacetophenone nor 4-hydroxy-3[isopenten-(2)-yl]-acetophenone were efficiently incorporated into dehydrotremetone. 相似文献
22.
Temporal variation in habitat selection breaks the catch‐22 of spatially contrasting predation risk from multiple predators 下载免费PDF全文
Karen Lone Atle Mysterud Terje Gobakken John Odden John Linnell Leif Egil Loe 《Oikos》2017,126(5):624-632
Predator avoidance depends on prey being able to discern how risk varies in space and time, but this is made considerably more complicated if risk is simultaneously present from multiple predators. This is the situation for an increasing number of mammalian prey species, as large carnivores recover or are reintroduced in ecosystems on several continents. Roe deer Capreolus capreolus in southern Norway illustrate a case in which prey face two predators with contrasting patterns of predation risk. They face a catch‐22 situation: spatially avoiding the risk from one predator (lynx Lynx lynx in dense habitat) implies exposure to the other (hunters in open habitat). Using GPS‐data from 29 roe deer, we tested for daily and seasonal variation in roe deer selection for habitat with respect to the habitats’ year‐round average risk level. Generally, roe deer altered their habitat selection between night and day in a pattern consistent with being able to avoid predicted risk from the nocturnal lynx during night and predicted risk from human hunters during day. However, seasonal variation in habitat selection only partially corresponded with the predicted seasonal variation in risk. Whereas roe deer avoided areas with high risk from hunters more strongly during the hunting season than in other seasons, there was a lack of selection towards areas and time periods lowering the risk of lynx predation during winter. It seems likely that the risk of starvation and thermal stress constrain roe deer habitat selection during this energetically challenging season with cold temperatures, snow cover and limited natural forage. The habitat selection pattern of roe deer fits thus only partly with the two contrasting risk gradients they face. Adjusting risk‐avoidance behavior temporally can be an adaptive response in the case of several predators whose predation patterns differ in space and time. 相似文献
23.
Egil Karlsbakk 《Marine Biology Research》2005,1(2):140-148
Marine fish from several locations along the west coast of Norway were examined for leeches. Seven leech species were detected, Calliobdella nodulifera (Malm, 1863) from codfish, flatfish and a ray, Calliobdella lophii van Beneden & Hesse, 1863 from Lophius piscatorius L., Platybdella anarrhichae (Diesing, 1859) on Anarhichas lupus L., Platybdella quadrioculata Malm, 1863 on Symphodus melops (L.), Oceanobdella sp. on Zeugopterus punctatus (Bloch), Malmiana brunnea (Johansson, 1896) on Myoxocephalus scorpius (L.) and Malmiana bubali Srivastava, 1966 on Taurulus bubalis (Euphrasen). Calliobdella nodulifera infected unrelated hosts (euryxenic); the others appeared to be host specialists (oio- or stenoxenic). Details on the occurrence of Calliobdella nodulifera on Enchelyopus cimbrius (L.) during 1 year are given, which together with other observations suggest that its life cycle exceeds a year. A brief account on the morphology of “Platybdella” quadrioculata is provided, justifying its transfer to the genus Oceanobdella Caballero, 1956 as O. quadrioculata comb. nov. With the new additions, the Norwegian marine piscicolid fauna contain 12 species. At least ten additional species, known from adjoining areas, also probably occur along the Norwegian coast. 相似文献
24.
Malvin Torsvik Amanda Häggblom Geir Egil Eide Erich Schmutzhard Kaare Vetvik Andrea Sylvia Winkler 《BMC endocrine disorders》2008,8(1):1-10
Background
Age- and sex-specific reference intervals are an important prerequisite for interpreting thyroid hormone measurements in children. However, only few studies have reported age- and sex-specific pediatric reference values for TSHbasal (TSH), free T3 (fT3), and free T4 (fT4) so far. Reference intervals are known to be method- and population-dependent. The aim of our study was to establish reference intervals for serum TSH, fT3, and fT4 from birth to 18 years and to assess sex differences.Methods
2,194 thyroid hormone tests obtained from a hospital-based pediatric population were included into our retrospective analysis. Individuals with diagnoses or medications likely to affect thyroid function were primarily excluded, as well as the diagnostic groups, if different from the purely healthy subgroup (n = 414). Age groups were ranging from 1 day to 1 month, 1 – 12 months, and 1 – 5, 6 – 10, 11 – 14, and 15 – 18 years, respectively. Levels of fT3, fT4 and TSH were measured on Advia® Centaur? automated immunoassay system.Results
The final sample size for reference data creation was 1,209 for TSH, 1,395 for fT3, and 1,229 for fT4. Median and 2.5/10/25/75/90/97.5 percentiles were calculated for each age group. Males had greater mean fT3 concentrations than females (p < 0.001). No sex-differences were found for TSH and fT4 between age-matched serum samples. Median concentrations of fT3, fT4 and TSH were greatest during the first month of life, followed by a continuous decline with age.Conclusion
Our results corroborate those of previous studies showing that thyroid hormone levels change markedly during childhood, and that adult reference intervals are not universally applicable to children. Moreover, differences of our reference intervals compared to previous studies were observed, likely caused by different antibody characteristics of various analytical methods, different populations or undefined geographic covariates, e.g. iodine and selenium status. 相似文献25.
Grete Helen Meisfjord Jrgensen Linn Borsheim Cecilie Marie Mejdell Eva Sndergaard Knut Egil Be 《Applied animal behaviour science》2009,120(1-2):94-99
Many horse owners tend to group horses according to gender, in an attempt to reduce aggressive interactions and the risk of injuries. The aim of our experiment was to test the effects of such gender separation on injuries, social interactions and individual distance in domestic horses. A total of 66 horses were recruited from 4 different farms in Norway and Denmark and divided into six batches. Within each batch, horses were allotted into one mare group, one gelding group and one mixed gender group, with most groups consisting of three or four animals. After 4–6 weeks of acclimatisation, a trained observer recorded all social interactions using direct, continuous observation 1 h in the morning and 1 h in the afternoon for three consecutive days. Recordings of the nearest neighbour of each horse were performed using instantaneous sampling every 10 min. The horses were inspected for injuries before grouping, day 1 after grouping and after 4–6 weeks. No significant effect of gender composition was found on social interactions (P > 0.05), spacing (P > 0.07) or injuries (P > 0.23). Eighty percent of all aggressive interactions recorded were threats, not involving physical contact. Horses with the smallest space allowance showed the highest mean number of aggressive interactions (28.6 ± 6.1 interactions per 6 h) compared to the mean of all the other batches (8.3 ± 1.0 interactions per 6 h). Very few injuries were found and most were superficial. In conclusion, gender composition does not seem to have any effect on aggression level, spacing or injuries. However, the early social experience of horses, management of feeding and space allowance probably represents more important factors for successful group housing of domestic horses. 相似文献
26.
Maria Teresa Landi Nilanjan Chatterjee Lynn R. Goldin Melissa Rotunno Kevin Jacobs Meredith Yeager Qizhai Li Dario Consonni Sholom Wacholder Ryan Diver Jarmo Virtamo Zhaoming Wang Kimberly F. Doheny Cathy Laurie Rayjean Hung James D. McKay John McLaughlin Ming-Sound Tsao Yufei Wang Lars Vatten Egil Arnesen Christine Bouchard Tonu Vooder Kristian Välk Chu Chen Patrick Sulem Thorunn Rafnar Wiebke Sauter Heike Bickeböller Jenny Chang-Claude Kari Stefansson Christopher I. Amos Sharon A. Savage Margaret A. Tucker Neil E. Caporaso 《American journal of human genetics》2009,85(5):679-74
Three genetic loci for lung cancer risk have been identified by genome-wide association studies (GWAS), but inherited susceptibility to specific histologic types of lung cancer is not well established. We conducted a GWAS of lung cancer and its major histologic types, genotyping 515,922 single-nucleotide polymorphisms (SNPs) in 5739 lung cancer cases and 5848 controls from one population-based case-control study and three cohort studies. Results were combined with summary data from ten additional studies, for a total of 13,300 cases and 19,666 controls of European descent. Four studies also provided histology data for replication, resulting in 3333 adenocarcinomas (AD), 2589 squamous cell carcinomas (SQ), and 1418 small cell carcinomas (SC). In analyses by histology, rs2736100 (TERT), on chromosome 5p15.33, was associated with risk of adenocarcinoma (odds ratio [OR] = 1.23, 95% confidence interval [CI] = 1.13–1.33, p = 3.02 × 10−7), but not with other histologic types (OR = 1.01, p = 0.84 and OR = 1.00, p = 0.93 for SQ and SC, respectively). This finding was confirmed in each replication study and overall meta-analysis (OR = 1.24, 95% CI = 1.17–1.31, p = 3.74 × 10−14 for AD; OR = 0.99, p = 0.69 and OR = 0.97, p = 0.48 for SQ and SC, respectively). Other previously reported association signals on 15q25 and 6p21 were also refined, but no additional loci reached genome-wide significance. In conclusion, a lung cancer GWAS identified a distinct hereditary contribution to adenocarcinoma. 相似文献
27.
The epidemiology of leprosy is characterized by heterogeneity in susceptibility and clustering of disease within households. We aim to assess the extent to which different mechanisms for heterogeneity in leprosy susceptibility can explain household clustering as observed in a large study among contacts of leprosy patients.We used a microsimulation model, parameterizing it with data from over 20,000 contacts of leprosy patients in Bangladesh. We simulated six mechanisms producing heterogeneity in susceptibility: (1) susceptibility was allocated at random to persons (i.e. no additional mechanism), (2) a household factor, (3, 4) a genetic factor (dominant or recessive), or (5, 6) half a household factor and half genetic. We further assumed that a fraction of 5%, 10%, and 20% of the population was susceptible, leading to a total of 18 scenarios to be fitted to the data. We obtained an acceptable fit for each of the six mechanisms, thereby excluding none of the possible underlying mechanisms for heterogeneity of susceptibility to leprosy. However, the distribution of leprosy among contacts did differ between mechanisms, and predicted trends in the declining leprosy case detection were dependent on the assumed mechanism, with genetic-based susceptibility showing the slowest decline. Clustering of leprosy within households is partially caused by an increased transmission within households independent of the leprosy susceptibility mechanism. Even a large and detailed data set on contacts of leprosy patients could not unequivocally reveal the mechanism most likely responsible for heterogeneity in leprosy susceptibility. 相似文献
28.
29.
Ian Mayer Justin Meager Jon Egil Skjæraasen Petra Rodewald Gisle Sverdrup Anders Fernö 《Environmental Biology of Fishes》2011,92(2):181-186
Brain and heart development is very plastic in teleost fishes, and receptive to changes in social and environmental conditions.
Domestication in salmonids has been reported to result in pronounced changes in both heart and brain morphology. In particular,
a high prevalence of heart deformities has been reported in farmed salmonids, which has been linked to increased stress responsiveness
that can impair survival of both farmed and escaped fish. Here we report for the first time that significant changes in heart
and brain morphology occur following domestication of Atlantic cod (Gadus morhua), an emerging aquaculture species. Juvenile farmed cod developed significantly larger hearts and smaller brains, by weight,
compared to their wild conspecifics. These differences occurred within the first captive generation, suggesting that they
were driven largely by the strong contrast in environmental and social conditions experienced within their respective rearing
environments. Changes in brain and heart morphology, as a consequence of domestication could affect the well-being and survival
of Atlantic cod raised under intensive aquaculture conditions. 相似文献
30.
Mats Fredriksen Alv A. Dahl Egil W. Martinsen Ole Klungsoyr Stephen V. Faraone Dawn E. Peleikis 《Attention deficit and hyperactivity disorders》2014,6(2):87-99
Few studies have examined the impact of childhood attention deficit hyperactivity disorder (ADHD) symptoms on adult ADHD functional outcomes. To address this issue dimensionally, ADHD symptoms in childhood and adulthood and their relation to educational deficits and work disability are studied in a clinical sample of adult patients with previously untreated ADHD. About 250 adults diagnosed systematically with ADHD according to DSM-IV were prospectively recruited. Primary outcomes were high school dropout and being out of the work last year. Childhood ADHD symptoms, sex differences, comorbidities of other mental disorders, and adult ADHD symptoms were examined by historical data, clinician interviews, and questionnaires. High levels of ADHD symptom severity in childhood were related to dropping out of high school [odds ratio (OR) = 3.0], as were higher numbers of hyperactive–impulsive symptoms in childhood. Significantly, more women than men were long-term work disabled (OR = 2.0). After adjusting for age and gender, persisting high levels of ADHD inattention symptoms in adulthood (OR = 2.5), number of comorbid disorders, and particularly anxiety disorders were significantly related to long-term work disability. Childhood hyperactive–impulsive symptoms and overall severity of childhood ADHD symptoms were associated with high school dropout rates; however, persisting ADHD inattention symptoms and comorbid mental disorders in adulthood were more correlated to occupational impairment. These findings underline proposals for studies on early recognition and interventions for ADHD and psychiatric comorbidity. They further suggest that inattentive symptoms be a focus of adult ADHD treatment and that workplace interventions be considered to prevent long-term work disability. 相似文献