The relationship of bird diversity to crop and non-crop heterogeneity in agricultural landscapes     

Matthew Hiron  Åke Berg  Sönke Eggers  Åsa Berggren  Jonas Josefsson  Tomas Pärt 《Landscape Ecology》2015,30(10):2001-2013

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Responses to water withdrawal of tobacco plants genetically engineered with the AtTPS1 gene: a special reference to photosynthetic parameters     

André M. Almeida  Anabela B. Silva  Susana S. Araújo  Luís A. Cardoso  Dulce M. Santos  José M. Torné  Jorge M. Silva  Matthew J. Paul  Pedro S. Fevereiro 《Euphytica》2007,154(1-2):113-126

We have previously obtained several lines of tobacco transformed with a trehalose-6-phosphate synthase gene of plant origin (Arabidopsis thaliana), involved in the first step of the biosynthesis of trehalose, a known osmoprotectant. Two showed distinct intensity of expression: high (B5H) and low (B1F). Such lines were analyzed for trehalose-6-phosphate content and the obtained results demonstrated to be in accordance with the expression results. In order to study the responses of photosynthesis to water deficit of transgenic lines in comparison to wild type (WT), three experiments were performed under different conditions: (1) Relative water (2) Leaf gas exchange (3) Modulated Chlorophyll a Fluorescence. Different responses in RWC of plant lines to water withdrawal were detected, with transgenic line B5H indicating less water loss after the water withdrawal period. Similar responses to water deficit regarding the leaf gas exchanges were recorded for the three lines. When subjected to water deficit stress situations, higher F _v/F _m, Φ_PSII and qP were detected for the transgenic lines. Under a SWC of 20% where higher values for such parameters were detected with special relevance for the B5H line, indicating a possible higher ability to withstand severe drought stress and to resist to prolonged periods without water than the B1F and WT lines.  相似文献   

Syntheses of (Z,E)-5,7-dodecadienol and (E,Z)-10,12-hexadecadienol,lepidoptera pheromone components,via zinc reduction of enyne precursors. test of pheromone efficacy against the Siberian moth     

Khrimian A  Klun JA  Hijji Y  Baranchikov YN  Pet'ko VM  Mastro VC  Kramer MH 《Journal of agricultural and food chemistry》2002,50(22):6366-6370

Efficient syntheses of (Z,E)-5,7-dodecadienol, a pheromone component of the Siberian moth, Dendrolimus superans sibiricus, and (E,Z)-10,12-hexadecadienol, a pheromone component of various Lepidoptera pheromones, were accomplished by cis reduction of the corresponding enynols with activated zinc. The most energetic reagent was zinc galvanized with copper and silver (Zn/Cu/Ag) that achieved rapid and high-yield reduction in methanol-water. The stereoselectivity of semi-hydrogenation was > or =98%. A process whereby zinc dust was continuously activated throughout the reduction with an acid was also satisfactory (95-98% cis). Field evaluation of the 1:1 mixture of (Z,E)-5,7-dodecadienol and (Z,E)-5,7-dodecadienal with the Siberian moth in Russia showed that the rubber septa pretreated with compound and stored at -80 degrees C were as effective as freshly treated septa. Moth responses to septa aged in open air indicated that lure effectiveness declined significantly after 2 weeks of aging. Thus, if rubber septa are used as pheromone dispensers in Siberian moth traps monitoring, they should be replaced biweekly with fresh septa for optimal trap effectiveness.  相似文献   

Conspecific attraction in loggerhead shrikes: implications for habitat conservation and reintroduction     

Matthew A Etterson 《Biological conservation》2003,114(2):199-205

The loggerhead shrike, Lanius ludovicianus, is a declining songbird that forms breeding aggregations. Despite such reports from several populations, only one statistical analysis of loggerhead shrike territory distribution has been published to date. I use a spatio-temporal simulation technique to test for deviations from randomness in the spatial distribution of point data that takes into account date of nest establishment. I apply this model to data on the distribution of shrike nests in Comanche County, Oklahoma, USA, collected over the 1998 and 1999 breeding seasons. When the data are considered without regard to date of nest-establishment, the results are equivocal; nests are significantly aggregated in 1999, but not 1998. However, when order of nest establishment is taken into account, later nests are significantly more likely to be closer than expected to conspecifics in both years. This is true even when the distribution of simple resources, such as suitable nest-trees, is included in the model. These results are consistent with the hypothesis that loggerhead shrikes ‘prospect’ for suitable habitat using the distribution of breeding conspecifics. This aspect of loggerhead shrike breeding ecology should be considered for both habitat conservation and captive breeding and reintroduction programs for this species.  相似文献   

Antioxidant capacity of different broccoli (Brassica oleracea) genotypes using the oxygen radical absorbance capacity (ORAC) assay     

Kurilich AC  Jeffery EH  Juvik JA  Wallig MA  Klein BP 《Journal of agricultural and food chemistry》2002,50(18):5053-5057

Antioxidant capacity of hydrophilic and lipophilic extracts from eight broccoli genotypes was compared using the oxygen radical absorbance capacity (ORAC) assay. Each genotype was analyzed for carotenoid, tocopherol, ascorbic acid, and flavonoid content. Results indicate that the antioxidant capacity of hydrophilic extracts ranged from 65.8 to 121.6 micromol trolox equivalents (TE)/g of tissue, and the capacity of lipophilic extracts ranged from 3.9 to 17.5 micromol TE/g. Ascorbic acid and flavonoid content of the hydrophilic extracts did not explain the total variation in antioxidant capacity of those extracts, suggesting either the presence of other antioxidant components that have yet to be identified or that the known antioxidants are producing synergistic effects. The carotenoids did correlate with antioxidant capacity of the lipophilic extracts and accounted for the majority of the variability in that fraction. The variability in hydrophilic and lipophilic antioxidant capacity found among these genotypes suggests that potential efficacy from antioxidants will vary considerably from genotype to genotype.  相似文献   

Longitudinal growth strain as a log and wood quality predictor for plantation-grown <Emphasis Type="Italic">Eucalyptus nitens</Emphasis> sawlogs     

Juan Valencia  Chris Harwood  Russell Washusen  Andrew Morrow  Matthew Wood  Peter Volker 《Wood Science and Technology》2011,45(1):15-34

Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old pruned Eucalyptus nitens trees from five thinning treatments in a plantation thinning trial in Tasmania. Growth strain data were gathered at breast height on each tree using the CIRAD-Forêt method. The effects of thinning treatment and tree diameter on LGS and its relationships to solid-wood traits determined in a processing trial were examined. LGS was significantly higher in the direction of the prevailing wind and was not significantly affected by either thinning treatment or tree diameter. An index of log end splitting was positively related to tree diameter, sawlog position (upper/lower), and LGS, which explained up to an additional 20% of the variance after tree diameter and log position were accounted for in a linear regression model. High LGS and log end splitting were significant indicators of increased board end splitting.  相似文献   

Effects of leaf age and tree size on stomatal and mesophyll limitations to photosynthesis in mountain beech (Nothofagus solandrii var. cliffortiodes)     

Whitehead D  Barbour MM  Griffin KL  Turnbull MH  Tissue DT 《Tree physiology》2011,31(9):985-996

Mesophyll conductance, g(m), was estimated from measurements of stomatal conductance to carbon dioxide transfer, g(s), photosynthesis, A, and chlorophyll fluorescence for Year 0 (current-year) and Year 1 (1-year-old) fully sunlit leaves from short (2 m tall, 10-year-old) and tall (15 m tall, 120-year-old) Nothofagus solandrii var. cliffortiodes trees growing in adjacent stands. Rates of photosynthesis at saturating irradiance and ambient CO(2) partial pressure, A(satQ), were 25% lower and maximum rates of carboxylation, V(cmax), were 44% lower in Year 1 leaves compared with Year 0 leaves across both tree sizes. Although g(s) and g(m) were not significantly different between Year 0 and Year 1 leaves and g(s) was not significantly different between tree heights, g(m) was significantly (19%) lower for leaves on tall trees compared with leaves on short trees. Overall, V(cmax) was 60% higher when expressed on the basis of CO(2) partial pressure at the chloroplasts, C(c), compared with V(cmax) on the basis of intercellular CO(2) partial pressure, C(i), but this varied with leaf age and tree size. To interpret the relative stomatal and mesophyll limitations to photosynthesis, we used a model of carbon isotopic composition for whole leaves incorporating g(m) effects to generate a surface of 'operating values' of A over the growing season for all leaf classes. Our analysis showed that A was slightly higher for leaves on short compared with tall trees, but lower g(m) apparently reduced actual A substantially compared with A(satQ). Our findings showed that lower rates of photosynthesis in Year 1 leaves compared with Year 0 leaves were attributable more to increased biochemical limitation to photosynthesis in Year 1 leaves than differences in g(m). However, lower A in leaves on tall trees compared with those on short trees could be attributed in part to lower g(m) and higher stomatal, L(s), and mesophyll, L(m), limitations to photosynthesis, consistent with steeper hydraulic gradients in tall trees.  相似文献   

Dynamic Modelling of Spatially Variable Catchment Hydrochemistry for Critical Loads Assessment     

Helen J. Foster  Matthew J. Lees  Howard S. Wheater  Colin Neal  Brian Reynolds 《Water, air, and soil pollution》2001,130(1-4):1283-1288

Concern about acidification in upland areas has brought about the need to model the stream hydrochemical response to deposition and land-use changes and calculate critical loads. Application of dynamic models such as MAGIC are preferable to steady-state methods, since they are able to produce an estimate of the time scale required to meet some water chemistry target given a reduction in acid deposition. These models typically consider annual changes in stream chemistry at one point. However, in order to protect biota from 'acid episodes', quantification of temporal variability needs to encompass event responses; in addition spatial variability across the catchment also needs to be considered. In this paper, modelling of both spatial and temporal variability is combined in a new framework which enables quantification of catchment hydrochemical variability in time and space. Both low and high flow hydro-chemical variability are quantified in terms of statistical distributions of ANC (Acid Neutralisation Capacity). These are then input as stochastic variables to an EMMA (End-Member Mixing Analysis) model which accounts for temporal variability and ANC is hence predicted as a function of time and space across the whole catchment using Monte-Carlo simulation. The method is linked to MAGIC to predict future scenarios and may be used by iteration to calculate critical loads. The model is applied to the headwaters of the River Severn at Plynlimon, Wales, to demonstrate its capabilities.  相似文献   

Autophagy genes are essential for dauer development and life-span extension in C. elegans     

Meléndez A  Tallóczy Z  Seaman M  Eskelinen EL  Hall DH  Levine B 《Science (New York, N.Y.)》2003,301(5638):1387-1391

Both dauer formation (a stage of developmental arrest) and adult life-span in Caenorhabditis elegans are negatively regulated by insulin-like signaling, but little is known about cellular pathways that mediate these processes. Autophagy, through the sequestration and delivery of cargo to the lysosomes, is the major route for degrading long-lived proteins and cytoplasmic organelles in eukaryotic cells. Using nematodes with a loss-of-function mutation in the insulin-like signaling pathway, we show that bec-1, the C. elegans ortholog of the yeast and mammalian autophagy gene APG6/VPS30/beclin1, is essential for normal dauer morphogenesis and life-span extension. Dauer formation is associated with increased autophagy and also requires C. elegans orthologs of the yeast autophagy genes APG1, APG7, APG8, and AUT10. Thus, autophagy is a cellular pathway essential for dauer development and life-span extension in C. elegans.  相似文献   

Diamond genesis,seismic structure,and evolution of the Kaapvaal-Zimbabwe craton     

Shirey SB  Harris JW  Richardson SH  Fouch MJ  James DE  Cartigny P  Deines P  Viljoen F 《Science (New York, N.Y.)》2002,297(5587):1683-1686

The lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of southern Africa shows variations in seismic P-wave velocity at depths within the diamond stability field that correlate with differences in the composition of diamonds and their syngenetic inclusions. Middle Archean mantle depletion events initiated craton keel formation and early harzburgitic diamond formation. Late Archean accretionary events involving an oceanic lithosphere component stabilized the craton and contributed a younger Archean generation of eclogitic diamonds. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new lherzolitic and eclogitic diamonds to the Archean diamond suite.  相似文献