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  • 1
    Electronic Resource
    Electronic Resource
    Root:shoot ratios of old and modern, tall and semi-dwarf wheats in a mediterranean environment (1990)
    Springer
    Plant and soil 122 (1990), S. 89-98 
    Details
    ISSN: 1573-5036
    Keywords: harvest index ; old and modern wheats ; root:shoot ratio ; Rht genes ; root dry matter ; root length ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines forRht dwarfing genes. Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased. The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns. At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUEgr) increased from old to modern varieties. The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUEgr of modern compared to old varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02444108
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  • 2
    Electronic Resource
    Electronic Resource
    Root:shoot ratios of old and modern, tall and semi-dwarf wheats in a mediterranean environment (1990)
    Springer
    Plant and soil 121 (1990), S. 89-98 
    Details
    ISSN: 1573-5036
    Keywords: harvest index ; old and modern wheats ; root:shoot ratio ; Rht genes ; root dry matter ; root length ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines for Rht dwarfing genes. Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased. The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns. At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUEgr) increased from old to modern varieties. The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUEgr of modern compared to old varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013101
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  • 3
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    Molecular and morphological supertrees for eutherian (placental) mammals (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-03-07
    Description: A large body of diverse comparative data now exists for a major phylogenetic synthesis of the higher-level relationships among eutherian (placental) mammals. We present such a phylogenetic synthesis using the composite trees or supertrees from the combined and separate analyses of their published molecular and morphological source phylogenies. Our combined and separate supertrees largely support the same suprafamilial taxa and orders, but different interordinal clades. These similarities and differences reinforce the continuing contributions of morphological studies, while highlighting the growing influence of molecular information on the field. As current summaries of past research, our supertrees emphasize opportunities for future work, while providing a step toward the eventual integration of the data and characters themselves.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, F G -- Miyamoto, M M -- Freire, N P -- Ong, P Q -- Tennant, M R -- Young, T S -- Gugel, K F -- New York, N.Y. -- Science. 2001 Mar 2;291(5509):1786-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology, Box 118525, University of Florida, Gainesville, FL 32611-8525, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11230694" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Evolution ; Humans ; Mammals/anatomy & histology/*classification/genetics ; Pedigree ; *Phylogeny
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Rapid formation and selective stabilization of synapses for enduring motor memories (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-12-01
    Description: Novel motor skills are learned through repetitive practice and, once acquired, persist long after training stops. Earlier studies have shown that such learning induces an increase in the efficacy of synapses in the primary motor cortex, the persistence of which is associated with retention of the task. However, how motor learning affects neuronal circuitry at the level of individual synapses and how long-lasting memory is structurally encoded in the intact brain remain unknown. Here we show that synaptic connections in the living mouse brain rapidly respond to motor-skill learning and permanently rewire. Training in a forelimb reaching task leads to rapid (within an hour) formation of postsynaptic dendritic spines on the output pyramidal neurons in the contralateral motor cortex. Although selective elimination of spines that existed before training gradually returns the overall spine density back to the original level, the new spines induced during learning are preferentially stabilized during subsequent training and endure long after training stops. Furthermore, we show that different motor skills are encoded by different sets of synapses. Practice of novel, but not previously learned, tasks further promotes dendritic spine formation in adulthood. Our findings reveal that rapid, but long-lasting, synaptic reorganization is closely associated with motor learning. The data also suggest that stabilized neuronal connections are the foundation of durable motor memory.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2844762/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2844762/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xu, Tonghui -- Yu, Xinzhu -- Perlik, Andrew J -- Tobin, Willie F -- Zweig, Jonathan A -- Tennant, Kelly -- Jones, Theresa -- Zuo, Yi -- R01 AG031871/AG/NIA NIH HHS/ -- R01 AG031871-02/AG/NIA NIH HHS/ -- England -- Nature. 2009 Dec 17;462(7275):915-9. doi: 10.1038/nature08389. Epub 2009 Nov 29.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19946267" target="_blank"〉PubMed〈/a〉
    Keywords: Aging/physiology ; Animals ; Dendrites/physiology ; Forelimb/physiology ; Memory/*physiology ; Mice ; Motor Cortex/*cytology/*physiology ; Motor Skills/*physiology ; Neuronal Plasticity/physiology ; Psychomotor Performance ; Pyramidal Cells/metabolism ; Seeds ; Synapses/*metabolism ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Prediction of chemical carcinogenicity in rodents from in vitro genetic toxicity assays (1987)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1987-05-22
    Description: Four widely used in vitro assays for genetic toxicity were evaluated for their ability to predict the carcinogenicity of selected chemicals in rodents. These assays were mutagenesis in Salmonella and mouse lymphoma cells and chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells. Seventy-three chemicals recently tested in 2-year carcinogenicity studies conducted by the National Cancer Institute and the National Toxicology Program were used in this evaluation. Test results from the four in vitro assays did not show significant differences in individual concordance with the rodent carcinogenicity results; the concordance of each assay was approximately 60 percent. Within the limits of this study there was no evidence of complementarity among the four assays, and no battery of tests constructed from these assays improved substantially on the overall performance of the Salmonella assay. The in vitro assays which represented a range of three cell types and four end points did show substantial agreement among themselves, indicating that chemicals positive in one in vitro assay tended to be positive in the other in vitro assays.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tennant, R W -- Margolin, B H -- Shelby, M D -- Zeiger, E -- Haseman, J K -- Spalding, J -- Caspary, W -- Resnick, M -- Stasiewicz, S -- Anderson, B -- New York, N.Y. -- Science. 1987 May 22;236(4804):933-41.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3554512" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carcinogens/pharmacology/*toxicity ; Chromosome Aberrations ; Drug Evaluation, Preclinical/methods ; Mutagenicity Tests/*methods ; Mutagens/pharmacology ; *Mutation ; Salmonella typhimurium/drug effects ; Sister Chromatid Exchange/drug effects
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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