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31.
LL. Lloyd 《The Annals of applied biology》1943,30(4):358-364
The incidence of the sewage fly, Psychoda alternata Say, breeding almost free from other insect competitors in a bacteria bed at Huddersfield is examined. Its general seasonal trend is marked by periods of peak output explained on the theory that there are two successions of generations running persistently and alternating with one another. Such behaviour has previously been demonstrated for another sewage fly, Spaniotoma minima , and has been shown to be instituted by irregular temperatures in autumn and spring. In Psychoda alternata a special type of intraspecific competition is set-up in the warmer months when the cycles are rapid, for the larvae of one succession must start life in a bed just depleted of food by the other. Therefore large and small outbursts of the fly tend to alternate. The discharges of solids from the bed have a detailed periodicity corresponding to the alternations in the successions of the fly. 相似文献
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33.
KARIN NORÉN ERS ANGERBJÖRN PÁLL HERSTEINSSON 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(1):18-26
The genetic composition of a population reflects several aspects of the organism and its environment. The Icelandic Arctic fox population exceeds 8000 individuals and is comprised of both coastal and inland foxes. Several factors may affect within-population movement and subsequent genetic population structure. A narrow isthmus and sheep-proof fences may prevent movement between the north-western and central part and glacial rivers may reduce movement between the eastern and central part of Iceland. Moreover, population density and habitat characteristics can influence movement behaviour further. Here, we investigate the genetic structure in the Icelandic Arctic fox population ( n = 108) using 10 microsatellite loci. Despite large glacial rivers, we found low divergence between the central and eastern part, suggesting extensive movement between these areas. However, both model- and frequency-based analyses suggest that the north-western part is genetically differentiated from the rest of Iceland (FST = 0.04, DS = 0.094), corresponding to 100–200 generations of complete isolation. This suggests that the fences cannot be the sole cause of divergence. Rather, the isthmus causes limited movement between the regions, implying that protection in the Hornstrandir Nature Reserve has a minimal impact on Arctic fox population size in the rest of Iceland. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 18–26. 相似文献
34.
Toni Gabaldón Christophe Dessimoz Julie Huxley-Jones Albert J Vilella Erik LL Sonnhammer Suzanna Lewis 《Genome biology》2009,10(9):1-3
A report of the 24th International Conference on Yeast Genetics and Molecular Biology, Manchester, UK, 19-24 July 2009. 相似文献
35.
S. Trachsel R. Messmer P. Stamp N. Ruta A. Hund 《Molecular breeding : new strategies in plant improvement》2010,25(1):91-103
A strong photosynthetic performance and rapid leaf development, are important indicators of vigorous early growth. The aim
of this study was to (1) evaluate the tropical maize (Zea mays L.) inbred lines CML444 and SC-Malawi for their photosynthetic performance at different growth stages and (2) assess quantitative
trait loci (QTL) of photosynthesis-related traits in their 236 recombinant inbred lines at the heterotrophic growth stage.
CML444 had a higher leaf chlorophyll (SPAD) content than SC-Malawi. Ten QTLs were found for the quantum efficiency of photosystem
II (ΦPSII; four), SPAD (three) and the specific leaf area (SLA; three). The relevance of seedling QTLs for ΦPSII, SPAD and SLA for yield formation is emphasized by seven collocations (bins 5.01, 7.03, 8.05) with QTLs for kernel number
and grain yield under field conditions. QTLs for SPAD at the V2 and at the reproductive stage did not collocate, indicating
differences in the genetic control of SPAD at different growth stages. Knowing which loci affect SLA, SPAD and ΦPSII simultaneously and which do not will help to optimize light harvest by the canopy. 相似文献
36.
Ruta M Wagner PJ Coates MI 《Proceedings. Biological sciences / The Royal Society》2006,273(1598):2107-2111
Although numerous studies have examined morphological diversification during major radiations of marine taxa, much less attention has been paid to terrestrial radiations. Here, we examine rates of character change over phylogeny and over time for Palaeozoic limbed tetrapods. Palaeozoic tetrapods show significant decreases in rates of character change whether the rate is measured per sampled cladistic branch or per million years along phylogeny. Given changes per branch, rates decrease significantly from the Devonian through the Pennsylvanian, but not from the Pennsylvanian through the Permian. Given changes per million years, rates decrease significantly over each boundary, although the decrease is least significant over the Pennsylvanian-Permian boundary. Decreasing rates per million years through the Permian might be an artefact of the method being able to ascribe longer durations to Permian branches than to Carboniferous ones; however, it is difficult to ascribe the general pattern of decreasing rates of change over time to sampling biases or methodological biases. Thus, the results implicate biological explanations for this pattern. 相似文献
37.
JM Rodríguez-Domínguez LL Ríos-Lara E Tapia-Campos R Barba-Gonzalez 《Biotechnic & histochemistry》2017,92(3):159-166
Preparations that contain well-spread metaphase chromosomes are critical for plant cytogenetic analyses including chromosome counts, banding procedures, in situ hybridization, karyotyping and construction of ideograms. Chromosome spreading is difficult for plants with large and numerous chromosomes. We report here a technique for obtaining cytoplasm-free, well-spread metaphases from two Amaryllidaceae species: Sprekelia formosissima (2n = 120) and Hymenocallis howardii (2n = 96). The technique has three main steps: 1) pretreatment to cause chromosome condensation, 2) dripping onto tilted slides coated with a thin layer of pure acetic acid and 3) application of steam and acetic acid to produce cytoplasmic hydrolysis, which spreads the chromosomes. 相似文献
38.
Fribourg M Moreno JL Holloway T Provasi D Baki L Mahajan R Park G Adney SK Hatcher C Eltit JM Ruta JD Albizu L Li Z Umali A Shim J Fabiato A MacKerell AD Brezina V Sealfon SC Filizola M González-Maeso J Logothetis DE 《Cell》2011,147(5):1011-1023
Atypical antipsychotic drugs, such as clozapine and risperidone, have a high affinity for the serotonin 5-HT(2A) G protein-coupled receptor (GPCR), the 2AR, which signals via a G(q) heterotrimeric G protein. The closely related non-antipsychotic drugs, such as ritanserin and methysergide, also block 2AR function, but they lack comparable neuropsychological effects. Why some but not all 2AR inhibitors exhibit antipsychotic properties remains unresolved. We now show that a heteromeric complex between the?2AR and the G(i)-linked GPCR, metabotropic glutamate 2 receptor (mGluR2), integrates ligand input,?modulating signaling output and behavioral changes. Serotonergic and glutamatergic drugs bind the mGluR2/2AR heterocomplex, which then balances Gi- and Gq-dependent signaling. We find that the mGluR2/2AR-mediated changes in Gi and Gq activity predict the psychoactive behavioral effects of a variety of pharmocological compounds. These observations provide mechanistic insight into antipsychotic action that may advance therapeutic strategies for disorders including schizophrenia and dementia. 相似文献
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40.
Juozas Kupcinskas Thomas Wex Alexander Link Marcis Leja Indre Bruzaite Ruta Steponaitiene Simonas Juzenas Ugne Gyvyte Audrius Ivanauskas Guntis Ancans Vitalija Petrenkiene Jurgita Skieceviciene Limas Kupcinskas Peter Malfertheiner 《PloS one》2014,9(1)