共查询到20条相似文献,搜索用时 15 毫秒
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《Current opinion in plant biology》2000,3(3):169
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A total of 25 aphid species were collected from 49 ornamental plant species in S?o Carlos-S?o Paulo, Brazil; 12 aphids were monophagous, four oligophagous and nine polyphagous. A total of 58 aphid-plant associations are recorded, 43 unknown from Brazil. Eucarazzia elegans (Ferrari, 1872) (Aphididae: Aphidinae: Macrosiphini) is recorded for the first time from Brazil, and Nectandra megapotamica Spreng. (Lauraceae) is recorded for the first time as host plant for Lizerius tuberculatus (E.E. Blanchard, 1939) (Drepanosiphidae: Drepanosiphinae: Lizeriini). We also describe the injuries caused by aphids to the ornamental plants. 相似文献
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Dominic Klyve 《Journal of the history of biology》2014,47(2):189-212
It is fairly well known that Darwin was inspired to formulate his theory of natural selection by reading Thomas Malthus’s Essay on the Principle of Population. In fact, by reading Darwin’s notebooks, we can even locate one particular sentence which started Darwin thinking about population and selection. What has not been done before is to explain exactly where this sentence – essentially Malthus’s ideas about geometric population growth – came from. In this essay we show that eighteenth century mathematician Leonhard Euler is responsible for this sentence, and in fact forms the beginning of the logical chain which leads to the creation of the theory of natural selection. We shall examine the fascinating path taken by a mathematical calculation, the many different lenses through which it was viewed, and the path through which it eventually influenced Darwin. 相似文献
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The knowledge of a population structure may constitute a powerful tool for mapping genes underlying susceptibility to Mendelian and complex diseases. To obtain a better understanding of the population structure of S?o Miguel Island (Azorean Archipelago, Portugal), we carried out a surname survey using the surnames listed in the most recent telephone book (2001). We identified 1315 different surnames in a total of 27,621 subscribers. The frequency of the different surnames was used to calculate the following parameters: isonymy (I), random component of inbreeding (FST), genetic diversity according to Fisher (alpha), migration rate according to Karlin-McGregor (v) and Nei's genetic distance. Eleven localities were selected, according to population size and geographic distribution, for analysis using the above parameters. Our results show that 51% of Salga's population and 52% of Sete Cidades's population are represented by six and eight surnames, respectively. These figures demonstrate the effective isolation of these two small places, which are located at opposite ends of S?o Miguel Island. Salga, Achada, and Sete Cidades present the lowest values of Fisher's alpha, indicating less genetic diversity. In contrast, the capital, Ponta Delgada, presents the highest value of alpha (78.13), indicating more genetic diversity. Our data indicate that the clustering of the localities corresponds to the geographic features of the island, where localities close together tend to share similar surnames. In conclusion, the population of S?o Miguel is relatively homogeneous and may constitute an ideal model for genetic mapping studies. 相似文献
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《Chronobiology international》2013,30(2):239-252
Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven São Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14–18 yrs of age who attended school Monday–Friday between 19:00 to 22:30 h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F(1,23) = 6.1; p = 0.02] and woke up earlier work days than nonworking students [F(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F(1,23) = 16.7; p < 0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F(1,23) = 10.8; p < 0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays, working girls took the shortest naps [F(1,23) = 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning. 相似文献
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Chen Zhang Lingxin Kong Qian Liu Xuan Lei Tao Zhu Jun Yin Birun Lin Zixin Deng Delin You 《PloS one》2013,8(2)
Quinoxaline-2-carboxylic acid (QXC) and 3-hydroxyquinaldic acid (HQA) feature in quinomycin family and confer anticancer activity. In light of the significant potency against cancer, the biosynthetic gene clusters have been reported from many different Streptomyces strains, and the biosynthetic pathway were proposed mainly based on the in vivo feeding experiment with isotope labeled putative intermediates. Herein we report another gene cluster from Streptomyces griseovariabilis subsp. bandungensis subsp. nov responsible for the biosynthesis of echinomycin (a member of quinomycin family, also named quinomycin A) and presented in vitro evidence to corroborate the previous hypothesis on QXC biosynthesis, showing that only with the assistance of a MbtH-like protein Qui5, did the didomain NRPS protein (Qui18) perform the loading of a L-tryptophan onto its own PCP domain. Particularly, it was found that Qui5 and Qui18 subunits form a functional tetramer through size exclusion chromatography. The subsequent hydroxylation on β-carbon of the loaded L-tryptophan proved in vitro to be completed by cytochrome P450-dependent hydroxylase Qui15. Importantly, only the Qui18 loaded L-tryptophan can be hydroxylated by Qui15 and the enzyme was inactive on free L-tryptophan. Additionally, the chemically synthesized (2S,3S) β-hydroxytryptophan was detected to be converted by the tryptophan 2,3-dioxygenase Qui17 through LC-MS, which enriched our previous knowledge that tryptophan 2,3-dioxygenase nearly exclusively acted on L-tryptophan and 6-fluoro-tryptophan. 相似文献
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Teixeira LR Fischer FM de Andrade MM Louzada FM Nagai R 《Chronobiology international》2004,21(2):239-252
Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven S?o Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14-18 yrs of age who attended school Monday-Friday between 19:00 to 22:30h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F(1,23)=6.1; p=0.02] and woke up earlier work days than nonworking students [F(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F(1,23)= 16.7; p <0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F(1,23)= 10.8; p <0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays working girls took the shortest naps [F(1,23)= 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning. 相似文献
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This study obtained baseline information for adult Odonata and assessed their conservation priorities and suitability as biological
indicators in S’Albufera Natural Park in Mallorca, Spain. At this site, human activities in and around the wetland have raised
concerns about their impact on the ecosystem. Investigations on adult diversity produced records of 14 species (four Zygoptera
and 10 Anisoptera) and included the first record of Erythromma viridulum for the park. Detrended Correspondence Analysis (DCA) ordination categorised study sites according to their geographical
locations in the park and showed clustering of the sites around particular species based on these locations. This pattern
might reflect the differences in brackishness in water supplied by different water sources. Canonical Correspondence Analysis
(CCA) indicated that some environmental factors were related to particular species. Water flow, vegetation, and depth and
size of a water body could discriminate stenotopic species from eurytopic species. Only a few species appeared to be tolerant
to the sites with high salinity and low oxygen concentration. The ordination results can be useful for establishing conservation
priorities with information of species diversity, abundance, distribution and flight period. Although, with the current limited
basic information, the use of Odonata species as biological indicators seems to be difficult, some clear relationships between
environmental factors and particular species indicate the great potential of using adult Odonata as biological indicators
in the park. 相似文献
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The objective of this study was to show which species of flies are responsible for human myiasis in the Brazilian state of Goiás and to determine the frequency of cases. Patients at the Clinical Hospital of the Federal University of Goiás (UFG) were examined, and any fly larvae found in their wounds were collected for taxonomic identification. First instar larvae were observed using light microscopy; second and third instars were examined using stereoscopy. The following screwworm flies were observed, in decreasing order of prevalence: Cochliomyia hominivorax, Sarcodexia lambens, Dermatobia hominis, Chrysomya albiceps, Chrysomya megacephala, Lucilia cuprina, and Eristalis tenax. Myiasis was most frequent in the legs in adults, male patients, elderly people, and people of reproductive age. It was lowest in children, females, and patients with neurologic or psychiatric disorders. Frequency was high in patients living in low socioeconomic conditions with poor personal hygiene. Education and sanitation measures are needed to counteract this situation. 相似文献
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Cdk2 has been viewed as a key cell cycle regulator that is essential for S phase progression. The recent discovery that Cdk2 is not required for cell proliferation in mice now shows that other factors must be able to replace Cdk2 in stimulating DNA replication. Experiments performed in Xenopus egg extracts identify the mitotic protein kinases Cdk1/Cyclin B and Cdk1/Cyclin A as likely candidates. These observations raise the intriguing possibility that Cdk1 normally participates in genome duplication in wild type cells. 相似文献
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The aim of this study was to investigate the feasibility of using short tandem repeats (STRs) to diagnose Edwards’ syndrome (ES). Quantitative fluorescence polymerase chain reaction (QF-PCR) was performed to amplify STR loci on chromosome 18, specifically D18S53, D18S59, and D18S488. The amplified products were subjected to a fluorescence signal analysis and their application to ES diagnosis was examined. Among the 807 cases that showed normal results in the karyotype analysis, 793 showed one or two fluorescence bands with a fluorescence intensity ratio of 1:1, and 14 cases showed 3 bands, which were false-positive results. ES was diagnosed in 9 samples. The sensitivities of D18S53, D18S59, and D18S488 for the diagnosis of ES were 77.78, 44.44, and 55.56 % and the specificities were 96.16, 96.03, and 96.28 %, respectively. The combined sensitivity of the three loci for diagnosing DS was 100 % (9/9), with a specificity of 98.27 % (793/807). QF-PCR amplification of STR loci had high sensitivity, strong specificity, and was simple and rapid. Thus, it might have wide clinical applications, and could be an ideal tool for large-scale genetic and prenatal diagnosis of ES. 相似文献
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