Pollen-mediated gene flow in wheat (Triticum aestivum L.) in a semiarid field environment in Spain

Transgenic wheat (Triticum aestivum L.) varieties are being developed and field-tested in various countries. Concerns regarding gene flow from genetically modified (GM) crops to non-GM crops have stimulated research to estimate outcrossing in wheat prior to the release and commercialization of any transgenic cultivars. The aim is to ensure that coexistence of all types of wheat with GM wheat is feasible in accordance with current regulations. The present study describes the result of a field experiment under the semi-arid climate conditions of Madrid, Spain, at two locations (??La Canaleja?? and ??El Encin?? experimental stations) in Madrid over a 3-year period, from 2005 to 2007. The experimental design consisted of a 50?×?50?m wheat pollen source sown with wheat cultivars resistant to the herbicide chlortoluron (??Deganit?? and ??Castan?? respectively) and three susceptible receptor cultivars (??Abental??, ??Altria?? and ??Recital??) sown in replicated 1?×?1?m plots at different distances (0, 1, 3, 5, 10, 20, 40, 80 and 100?m) and four directions. Outcrossing rates were measured as a percentage of herbicide-resistant hybrids using an herbicide-screening assay. Outcrossing was greatest near the pollen source, averaging 0.029?% at 0?m distance at ??La Canaleja?? and 0.337?% at ??El Encin??, both below the 0.9?% European Union regulated threshold, although a maximum outcrossing rate of 3.5?% was detected in one recipient plot. These percentages declined rapidly as the distance increased, but hybrids were detected at different rates at distances of up to 100?m, the maximum distance of the experiment. Environmental conditions, as drought in 2004?C2005 and 2005?C2006, may have influenced the extent of outcrossing. These assays carried out in wheat under semi-arid conditions in Europe provide a more complete assessment of pollen-mediated gene flow in this crop.     

Breeding antarctic krill in captivity

Antarctic krill were maintained in large aquaria at Port of Nagoya Aquarium, Japan, under controlled photoperiod and were fed on phytoplankton and enriched animal feed. Maturation and spawning were induced after the light?:?dark (L?:?D) cycle was increased from 8?:?16 or 12?:?12 to 24?:?0, or when the L?:?D cycle was held constant at 14?:?10. This study is one of the first studies that demonstrate initiation of maturation and spawning events of krill under controlled photoperiod. Out of three experimental batches of krill, a total of 28 spawning events were observed. The mean number of eggs per event was 1424 with a range between 139 and 3458. The mean hatching success per batch was 19.1%. The relation between photoperiod and maturity/spawning is discussed. Furthermore, hatching is compared to previous studies and the reason for the low success is discussed.     

The Path of Carbon in Photosynthesis: XII. SOME TEMPERATURE EFFECTS

The photosynthetic assimilation of radioactive carbon dioxidefor 2-minute periods by Scenedesmus has been studied at temperaturesranging from 25? to 44? C. All labelled intermediates ceaseto be formed at about 45? C. With rising temperature, the radioactivityreaching the sugar phosphate reservoirs decreases regularlywhile there is a sharp maximum in sucrose at 37? C, and a lesspronounced one in malic and aspartic acids above 40? C. A tentativeinterpretation of these effects is offered.     

Nuclear magnetic resonance study of exchangeable protons in ferrocytochrome c

Five well-resolved exchangeable proton resonances have been observed in horse ferrocytochrome c in the low-field region between ?10.0 and ?12.0 ppm. A resonance at ?11.6 ppm is assigned to an amino proton of His 26 on the basis of its magnetic field position, pH dependence and its correlation with histidine at this position in eight species. A resonance at ?10.9 ppm observed in horse and donkey ferrocytochrome c is assigned to a hydrogen-bonded ?-amino proton of Lys 60. This resonance shifts upfield with increasing salt and decreasing pH, with the shifts increasing as one goes from chloride to bromide to iodide. With less assurance, a resonance at ?10.6 ppm is assigned to the indole amino of Trp 59 and a resonance at ?10.3 ppm to the amino proton of the His 18. These resonances have been used to study the binding of small anions to ferrocytochrome c, the results of which show that inorganic phosphate, ADP and ATP all bind in the immediate vicinity of His 26, and that the inorganic phosphate has the greatest effect upon the imidazole amino exchange time.     

Stoichiometric patterns in foliar nutrient resorption across multiple scales

? Nutrient resorption is a fundamental process through which plants withdraw nutrients from leaves before abscission. Nutrient resorption patterns have the potential to reflect gradients in plant nutrient limitation and to affect a suite of terrestrial ecosystem functions. ? Here, we used a stoichiometric approach to assess patterns in foliar resorption at a variety of scales, specifically exploring how N?:?P resorption ratios relate to presumed variation in N and/or P limitation and possible relationships between N?:?P resorption ratios and soil nutrient availability. ? N?:?P resorption ratios varied significantly at the global scale, increasing with latitude and decreasing with mean annual temperature and precipitation. In general, tropical sites (absolute latitudes 相似文献   

Temperature effects on growing, feeding, and swimming energetics in the Patagonian blennie Eleginops maclovinus (Pisces: Perciformes)

The Patagonian blennie Eleginops maclovinus is a coastal and estuarine species, important in recreational and commercial fisheries, and with aquaculture potential. This study assessed the effect of temperature on feeding and the allocation of energy in growth and swimming in a sub-Antarctic population. For growth experiments, two groups of 8 juveniles were reared at 4 and 10?°C (corresponding to winter and summer habitat temperatures, respectively) for 3?months. Swimming experiments were conducted at 5 and 10?°C, measuring the oxygen consumption before and after forced swimming for 1?min at a speed of 10 total lengths (TL)/s. Temperature affects growth. TL increased 0.09?cm at 4?°C versus 0.30?cm at 10?°C. Body mass grew 0.49?g at 4?°C versus 1.65?g at 10?°C, whereas the Fulton’s condition factor increased 0.021 at 4?°C versus 0.080 at 10?°C. The ingested food was more than twofold higher at 10 than at 4?°C, while the feces produced at 4?°C was about twofold higher. The scope between baseline and peak oxygen consumption after forced swimming was affected by temperature, being 4.51 at 5?°C and 3.03 at 10?°C. The percentage energy expenditure until the return of baseline oxygen consumption values showed a marked temperature effect, being higher at 5?°C. We propose the existence of a trade-off in the allocation of energy between swimming activity and growth, with proportionally more energy being consumed at low temperatures for swimming than for other physiological functions like growth.     

Photochemical Performance of the Acidophilic Red Alga Cyanidium sp. in a pH Gradient

The acidophilic red alga Cyanidium sp. is one of the dominant mat-forming species in the highly acidic waters of Río Tinto, Spain. The culture of Cyanidium sp., isolated from a microbial mat sample collected at Río Tinto, was exposed to 9 different pH conditions in a gradient from 0.5 to 5 for 24?h and its physiological status evaluated by variable chlorophyll a fluorescence kinetics measurements. Maximum quantum yield was determined after 30?min, 1?h, 2?h, 4?h, 6?h and 24?h of exposure after 15?min dark adaptation. The effect of pH on photochemical activity of Cyanidium sp. was observable as early as 30?min after exposure and the pattern remained stable or with only minor modifications for 24?h. The optimum pH ranged from 1.5 to 2.5. A steep decrease of the photochemical activity was observed at pH below 1 even after 30?min of exposure. Although the alga had tolerated the exposure to pH?=?1 for at least 6?h, longer (24?h) exposure resulted in reduction of the photochemical activity. At pH above 2.5, the decline was more moderate and its negative effect on photochemistry was less severe. According to the fluorescence measurements, the red alga Cyanidium sp. is well-adapted to prevailing pH at its original locality at Río Tinto, i.e. pH of 1 to 3. The short-term survival in pH?相似文献   

Two photophobic responses in Volvox carteri

Phototaxis of Volvox carteri is the result of two photophobicresponses: stop and accelerationof flagellar activity in theanterior region of the colony. These responses of a colony fixedunder a microscope were analyzed quantitatively by cine-micrography. The phototactic sign of Volvox is temperature-dependent: itis positive at room temperature and negative at low temperature.When the temperature was lowered, the stop response to the on-stimuluswas reduced and changed to the acceleration response, whilethe acceleration response to the off-stimulus changed to thestop response. Decrease in light inteasity resulted in reduction in both stopresponses, i.e., the response to the on-stimulus at 24?C andthat to the off-stimulus at 16?C, but scarcely affected theacceleration responses. The action spectra of the photophobic responses at 24? and 14?Care similar, with a peak at 520 nm. (Received January 24, 1979; )     

Extracellular Enzyme Activity in a Willow Sewage Treatment System

This paper presents the results of studies on the activity of extra-cellular enzymes in soil-willow vegetation filter soil which is used in the post-treatment of household sewage in an onsite wastewater treatment system located in central Poland. Wastewater is discharged from the detached house by gravity into the onsite wastewater treatment system. It flows through a connecting pipe into a single-chamber septic tank and is directed by the connecting pipe to a control well to be further channelled in the soil-willow filter by means of a subsurface leaching system. Soil samples for the studies were collected from two depths of 5?cm and 1?m from three plots: close to the wastewater inflow, at mid-length of the plot and close to its terminal part. Soil samples were collected from May to October 2009. The activity of the extra-cellular enzymes was assayed by the fluorometric method using 4-methylumbelliferyl and 7-amido-4-methylcoumarin substrate. The ranking of potential activity of the assayed enzymes was the same at 5?cm and 1?m soil depths, i.e. esterase?>?phosphmomoesterase?>?leucine-aminopeptidase?>?β-glucosidase?>?α-glucosidase. The highest values of enzymatic activity were recorded in the surface layer of the soil at the wastewater inflow and decreased with increasing distance from that point.     

Carbon Stocks in an African Woodland Landscape: Spatial Distributions and Scales of Variation

Current knowledge of Africa’s carbon (C) pools is limited despite its importance in the global C budget. To increase the understanding of C stocks in African woodlands, we asked how C stocks in soil and vegetation vary across a miombo woodland landscape and to what degree and at what scales are these stocks linked? We sampled along a 5-km transect using a cyclic sampling scheme to allow geostatistical analyses. Soil C stocks in the top 5?cm (12.1?±?0.6?Mg?C?ha^?1 (±?SE)) and 30?cm depths (40.1?±?2.5?Mg?C?ha^?1) varied significantly at scales of a few meters (autocorrelation distance 14?m in 0–5-cm and 26?m in 0–30-cm interval), and aboveground (AG) woody C stocks (20.7?±?1.8?Mg?C?ha^?1) varied significantly at kilometer scales (1,426?m). Soil textural distributions were linked to topography (r ²?=?0.54) as were large-tree AG C stocks (r ²?=?0.70). AG C stocks were constrained to an upper boundary by soil texture with greater AG C being associated with coarser textured soils. Vegetation and soil C stocks were coupled in the landscape in the top 5?cm of soil (r ²?=?0.24) but not with deeper soil C stocks, which were coupled to soil clay content (r ²?=?0.38). This study is one of the most complete transect studies in an African miombo woodland, and suggests that C stock distributions are strongly linked to topography and soil texture. To optimize sampling strategies for C stock assessments in miombo, soil C should be sampled at more than 26?m apart, and AG C should be sampled at more than 1,426?m apart in plots larger than 0.5?ha.     

Neoplastic transformation in vitro by mixed beams of high-energy iron ions and protons

The radiation environment in space is complex in terms of both the variety of charged particles and their dose rates. Simulation of such an environment for experimental studies is technically very difficult. However, with the variety of beams available at the National Space Research Laboratory (NSRL) at Brookhaven National Laboratory (BNL) it is possible to ask questions about potential interactions of these radiations. In this study, the end point examined was transformation in vitro from a preneoplastic to a neoplastic phenotype. The effects of 1?GeV/n iron ions and 1?GeV/n protons alone provided strong evidence for suppression of transformation at doses ≤5?cGy. These ions were also studied in combination in so-called mixed-beam experiments. The specific protocols were a low dose (10?cGy) of protons followed after either 5-15?min (immediate) or 16-24?h (delayed) by 1?Gy of iron ions and a low dose (10?cGy) of iron ions followed after either 5-15?min or 16-24?h by 1?Gy of protons. Within experimental error the results indicated an additive interaction under all conditions with no evidence of an adaptive response, with the one possible exception of 10?cGy iron ions followed immediately by 1?Gy protons. A similar challenge dose protocol was also used in single-beam studies to test for adaptive responses induced by 232?MeV/n protons and (137)Cs γ radiation and, contrary to expectations, none were observed. However, subsequent tests of 10?cGy of (137)Cs γ radiation followed after either 5-15?min or 8?h by 1?Gy of (137)Cs γ radiation did demonstrate an adaptive response at 8?h, pointing out the importance of the interval between adapting and challenge dose. Furthermore, the dose-response data for each ion alone indicate that the initial adapting dose of 10?cGy used in the mixed-beam setting may have been too high to see any potential adaptive response.     

Toxicity of cholecalciferol to rats in a multi-species bait

The effectiveness of Feracol?, a possum control paste bait containing 0.8% cholecalciferol, as a rodenticide has been assessed in cage and field trials. Caged rats were provided with toxic bait in choice and no-choice tests. Feracol? was readily eaten when presented as the sole food source or with other food, and was effective at killing rats in both situations. Wild-caught and laboratory rats (n =?35), comprising both ship (Rattus rattus) and Norway rats (R.?norvegicus), were presented with 30 g of Feracol? alone or with an equivalent toxic bait over 48 h. Thirty-four rats died in an average of 4.0 days. Having established that the paste, originally designed for possum control, is also an effective rodenticide for rat control, field trials were initiated with the paste delivered in the field in Philproof? and Striker? bait stations. Monitoring of rat numbers before and after application of toxic bait was undertaken at three trial sites, Lions Hut, Mangaone and Pakoakoa, in Te Urewera National Park in the North Island of New?Zealand. Rat population density was assessed using tracking tunnels. Philproof? bait stations containing 200 g of Feracol? were placed 50 m apart on grids at Lions Hut and monitoring was undertaken at one location per hectare using tracking tunnels. At Mangaone and Pakoakoa, two Striker? bait stations containing 18 g of Feracol? were sited at 25-m intervals on lines 150 m apart, and monitoring was undertaken with five lines of 10 tunnels at 50-m intervals. At Lions Hut, rat tracking decreased from 78% to 3% of tunnels tracked; at Mangaone the reduction was 51% to 0%; and at Pakoakoa from 36% to 0%. These trials demonstrate that Feracol? is effective at reducing both moderate and high concentrations of ship rats in the Philproof? and Striker? bait station delivery systems.     

Decreased body weight in young Osterix-Cre transgenic mice results in delayed cortical bone expansion and accrual

Conditional gene inactivation using the Cre/loxP system has lead to significant advances in our understanding of the function of genes in a wide range of disciplines. It is becoming increasingly apparent in the literature, that Cre transgenic mice may themselves have a phenotype. In the following study we describe the bone phenotype of a commonly used Cre transgenic mouse line to study osteoblasts, the Osx-GFP::Cre (Osx-Cre) mice. Cortical and trabecular bone parameters were determined in the femurs of Osx-Cre mice at 6 and 12?weeks of age by microtomography (μCT). At 6?weeks of age, Osx-Cre mice had reduced body weight by 22% (P?相似文献   

Ultra-sensitive Quantification of Sub-nanomolar Levels of Iodine in Blood Serum Samples by Kinetic-spectrophotometric Method

A simple and sensitive kinetic-spectrophotometric method is developed for the determination of trace amounts of iodine in blood serum samples based on its catalytic effect on the oxidation of Nile Blue A by potassium bromate in sulfuric acid medium and at 25°C. The absorbance is measured at 595.5?nm with the fixed-time method. The optimization of the operating conditions regarding concentration of the reagents, temperature, and interferences are also investigated. The calibration curve is linear over the concentration range between 20.0 to 500.0?ng?ml(-1) of iodine with good precision and accuracy. The detection limit of the method is down to 12.0?ng?ml(-1). The relative standard deviation for a standard solution of 100.0?ng?ml(-1) of iodine is 1.32% (n?=?10). The proposed method provides a highly sensitive, selective, and relatively rapid assay for iodine at ultra trace level without any pre-concentration and separation step. The method was applied to the determination of iodine in blood serum samples. The analytical results of the real samples were in excellent agreement with standard method.     

Plasmon Resonances in V-Shaped Gold Nanostructures

Using numerical simulations, we examine the change in plasmon resonance behavior in gold nanorod structures that have a V shape. The reduction in symmetry compared to linear rods causes two different longitudinal-type resonances to appear in a single structure, and the relative intensity and hybridization of these can be controlled by varying the angle of the arms of the ??V.?? The resonances may also be selectively excited by controlling the polarization of the incident light, thereby providing a convenient way to control a nanoscale optical electric field using far-field parameters. For example, the wavelength at which a strong resonance occurs in the V-shaped structures studied can be switched between 630 and 900?nm by a 90° rotation of the polarization of the incident light. Due to the symmetry of the targets, there will be three types of special near-field location; a location at which the electric field intensity is enhanced by either resonance, a location at which the electric field intensity is enhanced by the 630?nm resonance but not by the 890?nm resonance, and a location at which the electric field intensity is enhanced by the 890?nm resonance but not by the 630?nm one.     

The Effects of Temperature on Root Initiation in Detached Cotyledons of Sinapis alba L.

A thermoplate system is described which enables uniformly illuminatedpetri dish cultures to be maintained under a range of temperatureregimes. The system is evaluated and used to investigate theeffects of incubation temperatures between 10 and 35 ?C on rootinitiation. Sinapis cotyledons root most rapidly and in greatest numbersat 25 and 30 ?C. Below 25 ?C, rooting is reduced and delayed,and above 30 ?C rooting is prevented. The optimum temperaturefor initiation of primordia is close to 25 ?C, where, after4 days over 80 per cent of petioles have at least one primordiumand over half of these are already elongating. Initiation isconsiderably reduced at temperatures above 30 ?C and below 25?C and primordium elongation either fails to take place (35?C) or is delayed (20, 13, 10 ?C). At 25 ?C, 90 per cent of the primordia are initiated in theterminal 1.5 mm of the petriole. A similar pattern occurs atother temperatures, but the relative numbers of primordia initiatedin the upper petiole are increased when cotyledons are incubatedat temperatures below 25 ?C. At 25 ?C a higher proportion ofprimordia are initiated in the upper petiole in cotyledons withmany primordia than in cotyledons with few, but the developmentof primordia to the elongation stage is not affected by theirposition in the petiole nor by the numbers of primordia present.     

Body-height and inbreeding in France

Dahlberg's ('43) hypothesis that heterosis is a major component of the secular trend towards increased stature is supported by the significant negative correlation between stature and the coefficient of inbreeding in 70 departments of France. This phenomenon is especially evident after the onset of puberty, (r at age 7 = ?0.25 for boys: ?0.24 for girls; but r at age 14 = ?0.44 for boys and ?0.56 for girls) and is found also in adults.