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  • 1
    Publication Date: 2011-11-01
    Description: Endocycles are variant cell cycles comprised of DNA synthesis (S)- and gap (G)-phases but lacking mitosis. Such cycles facilitate post-mitotic growth in many invertebrate and plant cells, and are so ubiquitous that they may account for up to half the world's biomass. DNA replication in endocycling Drosophila cells is triggered by cyclin E/cyclin dependent kinase 2 (CYCE/CDK2), but this kinase must be inactivated during each G-phase to allow the assembly of pre-Replication Complexes (preRCs) for the next S-phase. How CYCE/CDK2 is periodically silenced to allow re-replication has not been established. Here, using genetic tests in parallel with computational modelling, we show that the endocycles of Drosophila are driven by a molecular oscillator in which the E2F1 transcription factor promotes CycE expression and S-phase initiation, S-phase then activates the CRL4(CDT2) ubiquitin ligase, and this in turn mediates the destruction of E2F1 (ref. 7). We propose that it is the transient loss of E2F1 during S phases that creates the window of low Cdk activity required for preRC formation. In support of this model overexpressed E2F1 accelerated endocycling, whereas a stabilized variant of E2F1 blocked endocycling by deregulating target genes, including CycE, as well as Cdk1 and mitotic cyclins. Moreover, we find that altering cell growth by changing nutrition or target of rapamycin (TOR) signalling impacts E2F1 translation, thereby making endocycle progression growth-dependent. Many of the regulatory interactions essential to this novel cell cycle oscillator are conserved in animals and plants, indicating that elements of this mechanism act in most growth-dependent cell cycles.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330263/" 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/PMC3330263/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zielke, Norman -- Kim, Kerry J -- Tran, Vuong -- Shibutani, Shusaku T -- Bravo, Maria-Jose -- Nagarajan, Sabarish -- van Straaten, Monique -- Woods, Brigitte -- von Dassow, George -- Rottig, Carmen -- Lehner, Christian F -- Grewal, Savraj S -- Duronio, Robert J -- Edgar, Bruce A -- 5 P50GM66050/GM/NIGMS NIH HHS/ -- GM51186/GM/NIGMS NIH HHS/ -- GM57859/GM/NIGMS NIH HHS/ -- MOP-86622/Canadian Institutes of Health Research/Canada -- R01 GM051186/GM/NIGMS NIH HHS/ -- R01 GM051186-14A1/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Oct 30;480(7375):123-7. doi: 10.1038/nature10579.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉German Cancer Research Center (DKFZ)-Zentrum fur Molekulare Biologie der Universitat Heidelberg Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22037307" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Cycle/*physiology ; Drosophila Proteins/*metabolism ; Drosophila melanogaster/*cytology/*enzymology/growth & development/metabolism ; E2F Transcription Factors/*metabolism ; Female ; Male ; S Phase/physiology ; Salivary Glands/cytology ; Ubiquitin-Protein Ligases/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    ISSN: 1572-9680
    Keywords: agroforestry ; Leucaena leucocephala ; Eucalyptus tereticornis ; Acacia species ; rainfed agriculture ; grass yield ; net returns ; north India
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Some conservation based agroforestry systems (AFS) were developed for possible adoption in place of high risk rainfed farming on land capability classes Ito IV of a typical topo-sequence of foothill north India. The agri-silvi-horticulture system integrating leucaena, lemon, papaya and turmeric on class I irrigated land provided sustainable mean net returns of Rs. 17066 against Rs. 7852 ha.−1 yr.−1 from double cropped agricultural system. The intercropping of cluster beans with leucaena gave the highest net returns of Rs. 3540 ha.−1 yr.−1 in the agri-silvicultural system adopted on class II land. Eucalyptus terettcornis (Smith) in top and Bhabbar grass (Eulaliopsis binata Retz) in the understorey on a sandy loam class III land gave four years (1985–1988) mean air dry grass yield of 4.2 (used for paper pulp) from October and 1.19 t. ha−1 yr.−1 (used for fodder) from June cut. The net returns from grass alone were Rs. 4672 against Rs. 1679 ha.−1 yr.−1 from rainfed field crops raised on an adjoining plot. The returns from trees would be additional. Bhabbar grass raised under Acacia species on a 25 to 30% sloping gravelly class IV land provided yield varying from 2.18 to 4.31 from October cut and 0.50 to 1.1 t. ha.−1 yr.−1 from June cut with 6 years mean of 3.9 t. ha.−1 yr.−1 which at 1988 prices provided net returns of Rs. 2402 ha−1. These AFS proved superior to traditional farming on each land capability class.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Agroforestry systems 21 (1993), S. 177-190 
    ISSN: 1572-9680
    Keywords: competition ; trees ; grasses and spatial relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Adequate evaluation of competition interfaces of tree growth on intercrops is an important consideration in the assessment of agroforestry systems. Spatial methods wherein positional effect of an observation with respect to trees or columns of trees can be accounted for were examined. Yield ofbhabbar grass (Eulaliopsis binata Ritz) planted under paired and staggered columns of Eucalyptus (Eucalyptus tereticornis Smith) was analysed for four years. Grass production at 7 positions recorded across staggered and paired tree columns was significantly different. Spatial correlations among contiguous observations across paired tree columns were significant. Cyclicity corresponding to seven columns of grass of 3.5 m distance between paired tree columns explained variation in grass production significantly during the first observation year. Additional competition interfaces at 1.75 m and 1.17 m appeared in the subsequent years. These competition interfaces were attributed to pairing of trees and staggering. Error distributions of fitting of cyclic patterns were more acceptable as compared to ANOVA. Possibilities of the use of this methodology in many other agroforestry situations are discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9680
    Keywords: Leucaena leucocephala ; maize (Zea mays) ; wheat (Triticum aestivum) ; leaf biomass ; nitrogen substitution ; residual effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a 3-year field study, the effects of substitution of nitrogen requirement of maize through Leucaena leaves were studied on runoff, soil loss, maize and wheat yield and economic returns. The treatments were (1) 80 kg N ha-;1 all through Leucaena leaves (80 L), (2) 40 kg N through Leucaena leaves + 40 kg N ha-;1 through fertilizer (40 L + 40 F), (3) 20 kg N through Leucaena leaves + 60 kg N ha-;1 through fertilizer (20 L + 60 F), (4) 80 kg N ha-;1 all through fertilizer (80 F), and (5) control (No fertilizer). Green Leucaena leaf biomass (containing 3.3% N on dry basis) was incorporated every year in 15 cm top soil two weeks before sowing of summer maize. Other treatments being almost equal, runoff was reduced marginally in treatment 20 L + 60 F which was attributed to better crop growth in this treatment. Mean minimum soil loss (6.202 t ha-;1) also occurred in treatment 20 L + 60 F. Soil loss in 80 L was 13% less than in 80 F. Maize yield was at par in 80 L and 80 F. However, mean maximum yield of maize was obtained with 20 L + 60 F. Residual effect of incorporation of Leucaena leaves to maize crop was observed on wheat yield. The mean yield differences were statistically at par in all the treatments except control. The total mean net returns were statistically at par in 80 L and 80 F. However, significantly higher mean net returns (Rs 6811 ha-;1; one US$ = Rs30) were obtained with 20 L + 60 F. Substitution of N through Leucaena leaves even in small quantity may be helpful to small holders, particularly where chemical fertilizers are in short supply or too expensive.
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  • 5
    ISSN: 1572-9680
    Keywords: alkali soils ; agroforestry ; rainwater conservation ; biomass accumulation ; chemical composition ; Eucalyptus tereticornis ; Acacia nilotica ; Parkinsonia aculeata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This field study started in July 1982 on a typical alkali soil (Aquic Natrustalf, ESP 99.7) examined the growth responses to some management practices in a unified system planned to establish agroforestry. The planting of 3 salt tolerant tree species with two methods: on flat natural surface (FSPB) without rainwater conservation and on ridges (0.6 m high, 1.5 m at top and 2.5 m at base) having parallel trenches of the same section to store 300 mm of monsoon rainwater; constituted the main plot treatments. The tree planting with and without forage grassDiplachne fusca linn. in the inter-row space and planting in shallow (15 × 60 cm) and deep (15 × 180 cm to cross hard pan) augerholes filled with amendment treated soil (2 kg gypsum, 8 kg FYM, 50 g N, 10 g zinc sulphate and original soil) formed the sub and sub-plot treatments replicated 4 times in a split-split plot design. The mean plant height ofEucalyptus tereticornis smith;Acacia nilotica L; andParkinsonia aculeata L. in 2 years period was 273 and 328, 240 and 240 and 211 and 199 cm respectively with and without rainwater conservation. The corresponding height of the 3 tree species was 314 and 287, 250 and 231 and 207 and 203 cm with and without grass in the inter-row space. Similarly the plant height was 247 and 354, 182 and 298, 172 and 238 in shallow and deep augerholes respectively. The tree height and basal diameter differences with and without rainwater conservation and grass growth remained non-significant but deep augerhole planting was markedly superior to the shallow augerhole planting. The 2 year biomass accumulation also followed the same trend. The grass competed with trees for moisture during hot dry summer months and increased plant mortality particularly in the shallow augerholes and more so on ridges. The plant roots, essentially, remained confined to the amended soil of the augerholes in FSPB but proliferated in the loose soil of ridges or grass and submergence ameliorated surface soil of trenches.Acacia nilotica accumulated low sodium and had the lowest Na:Ca and Na:K ratio. It was found more promising than eucalyptus and parkinsonia as it experienced low mortality and had better chemical constitution to tolerate adverse alkali soil environment. The rainwater conservation system needed further evaluation before drawing final conclusions.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 81 (1984), S. 75-83 
    ISSN: 1573-5036
    Keywords: Coarse fragments ; Gravel concentration ; Crop yield ; Monetary returns ; Sorghum fodder ; Maize ; Cowpea ; Sesamum ; Taramira
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soil characteristics in the crop root zone are critical to soil water and nutrient availability to rainfed crops and determine crop production in coarse textured soils. A four-year field study was conducted in the foot-hills of North Himalayas near Chandigarh (India) on a coarse textured soil (Gravelly udic ustocrepts) to evaluate the effect of varying soil profile gravel concentration on the yield of rainfed crops of Taramira (Eruca sativa Mill.) in winter followed by maize (Zea mays L.), sorghum (Sorghum vulgare Pers.), cowpea (Vigna unguiculata L.) and sesamum (Sesamum indicum L.) in summer. Taramira gave a mean grain yield of 683, 410 and 275 kg ha−1 at gravel concentration (GC) of 18, 28 and 40 percent by volume in the surface one metre soil depth. The grain and forage yield of summer crops decreased with the increasing GC. The gross monetary returns decreased in the order: Sorghum fodder, cowpea, sesamum and maize. The dilution of soil mass with increasing GC and corresponding decrease in nutrient and water holding capacity of the soil appears to have depressed the crop yields. The results indicated that the legume which can also conserve rainwater with dense canopy like cowpea or crops having vigorous fibrous root system and are relatively drought tolerant like sorghum may provide better economic returns in light textured soil containing gravel upto 40 percent.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant foods for human nutrition 28 (1978), S. 211-218 
    ISSN: 1573-9104
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Qualitative and quantitative analysis of polar lipids in sun flower (Helianthus annuus L.) seed is reported in the present study. Ten classes of polar lipids i.e. phosphatidic acid, phosphatidyl inositol, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl glycerol, diphosphatidyl glycerol, digalactosyl diglyceride, monogalactosyl diglyceride, esterified sterol glycoside and free fatty acids have been identified. Phosphatidyl choline and phosphatidyl inositol formed the major phosphatide fractions. Only four fatty acids i.e. palmitic, stearic, oleic and linoleic acids were present in measurable amounts in the total polar lipids. There was a great variation in the fatty acid composition in different classes of polar lipids. Arachidic acid was present in all the individual phosphatide fractions. Phosphatidyl glycerol was highly unsaturated followed by esterified sterolglycoside, phosphatidic acid, phosphatidyl ethanolamine + phosphatidyl glycerol, diphosphatidyl glycerol and monogalactosyl diglyceride.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2012-01-06
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 9
    Publication Date: 2012-01-25
    Description: The target-of-rapamycin pathway couples nutrient availability with tissue and organismal growth in metazoans. The key effectors underlying this growth are, however, unclear. Here we show that Maf1, a repressor of RNA polymerase III-dependent tRNA transcription, is an important mediator of nutrient-dependent growth in Drosophila. We find nutrients promote tRNA synthesis during larval development by inhibiting Maf1. Genetic inhibition of Maf1 accelerates development and increases body size. These phenotypes are due to a non–cell-autonomous effect of Maf1 inhibition in the fat body, the main larval endocrine organ. Inhibiting Maf1 in the fat body increases growth by promoting the expression of brain-derived insulin-like peptides and consequently enhanced systemic insulin signaling. Remarkably, the effects of Maf1 inhibition are reproduced in flies carrying one extra copy of the initiator methionine tRNA, tRNAiMet. These findings suggest the stimulation of tRNAiMet synthesis via inhibition of dMaf1 is limiting for nutrition-dependent growth during development.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
    Publication Date: 1986-09-01
    Print ISSN: 0167-4366
    Electronic ISSN: 1572-9680
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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