Zur Möglichkeit einer Schätzung von F2-Leistungen (je Pflanze) bei einfachen Maishybriden auf Grund der entsprechenden Angaben über F1 und P     

Igor Grebenščikov 《Genetic Resources and Crop Evolution》1980,28(2):239-255

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Zur quantitativ-genetischen Analyse der Ertragskomponenten beim Kürbis     

Igor Grebenščikov 《Genetic Resources and Crop Evolution》1964,12(1):93-106

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Exposure to sulfosulfuron in agricultural drainage ditches: field monitoring and scenario-based modelling     

Brown CD  Dubus IG  Fogg P  Spirlet M  Gustin C 《Pest management science》2004,60(8):765-776

Field monitoring and scenario-based modelling were used to assess exposure of small ditches in the UK to the herbicide sulfosulfuron following transport via field drains. A site in central England on a high pH, clay soil was treated with sulfosulfuron, and concentrations were monitored in the single drain outfall and in the receiving ditch 1 km downstream. Drainflow in the nine months following application totalled 283 mm. Pesticide lost in the first 12.5 mm of flow was 99% of the total loading to drains (0.5% of applied). Significant dilution was observed in the receiving ditch and quantifiable residues were only detected in one sample (0.06 microg litre(-1)). The MACRO model was evaluated against the field data with minimal calibration. The parameterisation over-estimated the importance of macropore flow at the site. As a consequence, the maximum concentration in drainflow (2.3 microg litre(-1)) and the total loading to drains (0.76 g) were over-estimated by factors of 2.4 and 5, respectively. MACRO was then used to simulate long-term fate of the herbicide for each of 20 environmental scenarios. Resulting estimates for concentrations of sulfosulfuron in a receiving ditch were weighted according to the prevalence of each scenario to produce a probability distribution of daily exposure.  相似文献   

The molecular mechanism of thermal noise in rod photoreceptors     

S Gozem  I Schapiro  N Ferré  M Olivucci 《Science (New York, N.Y.)》2012,337(6099):1225-1228

Spontaneous electrical signals in the retina's photoreceptors impose a limit on visual sensitivity. Their origin is attributed to a thermal, rather than photochemical, activation of the transduction cascade. Although the mechanism of such a process is under debate, the observation of a relationship between the maximum absorption wavelength (λ(max)) and the thermal activation kinetic constant (k) of different visual pigments (the Barlow correlation) indicates that the thermal and photochemical activations are related. Here we show that a quantum chemical model of the bovine rod pigment provides a molecular-level understanding of the Barlow correlation. The transition state mediating thermal activation has the same electronic structure as the photoreceptor excited state, thus creating a direct link between λ(max) and k. Such a link appears to be the manifestation of intrinsic chromophore features associated with the existence of a conical intersection between its ground and excited states.  相似文献   

Involvement of ATP‐sensitive K+ channels in the peripheral antinociceptive effect induced by ketamine     

Thiago RL Romero  Igor DG Duarte 《Veterinary anaesthesia and analgesia》2013,40(4):419-424

ObjectiveTo investigate the contribution of K⁺ channels on peripheral antinociception induced by ketamine.Study designProspective experimental study.Animals110 male Wistar rats weighing 160–200 g.MethodsThe paw pressure required to elicit limb flexion was designated as the nociceptive threshold. Hyperalgesia was induced by intraplantar injection of prostaglandin E₂. All drugs were administered locally into the right hind paw of rats. Ketamine was administered into the right hind paw 2 hours and 55 minutes after local injection of PGE₂. Tetraethylammonium was administered 30 minutes prior to ketamine and the other K⁺ channel blockers, glibenclamide, dequalinium and paxilline, were administered 5 minutes prior to ketamine.ResultsProstaglandin E₂ (2 μg per paw) induced hyperalgesia. Ketamine (10, 20, 40 and 80 μg per paw) elicited a local peripheral antinociceptive effect that was antagonized by a specific blocker of ATP‐sensitive K⁺ channels, glibenclamide (20, 40 and 80 μg per paw). In another experiment, the non‐selective voltage‐dependent K⁺ channel blocker tetraethylammonium (30 μg per paw) and small and large conductance blockers of Ca²⁺‐activated K⁺ channels, dequalinium (50 μg per paw) and paxilline (20 μg per paw), were ineffective at blocking the effect of a local ketamine injection.Conclusions and clinical relevanceAnalysis of these results provides evidence that ketamine, may in part, induce peripheral antinociceptive effects by ATP‐sensitive K⁺ channel pathway activation.  相似文献   

Magnetic Resonance Imaging for Rapid Screening for the Nephrotoxic and Hepatotoxic Effects of Microcystins     

Aleksandra Milutinovi?  Ruda Zorc-Pleskovi?  Marko ?ivin  Andrej Vovk  Igor Se?a  Du?an ?uput 《Marine drugs》2013,11(8):2785-2798

In vivo visualization of kidney and liver damage by Magnetic Resonance Imaging (MRI) may offer an advantage when there is a need for a simple, non-invasive and rapid method for screening of the effects of potential nephrotoxic and hepatotoxic substances in chronic experiments. Here, we used MRI for monitoring chronic intoxication with microcystins (MCs) in rat. Male adult Wistar rats were treated every other day for eight months, either with MC-LR (10 μg/kg i.p.) or MC-YR (10 μg/kg i.p.). Control groups were treated with vehicle solutions. T₁-weighted MR-images were acquired before and at the end of the eight months experimental period. Kidney injury induced by the MCs presented with the increased intensity of T₁-weighted MR-signal of the kidneys and liver as compared to these organs from the control animals treated for eight months, either with the vehicle solution or with saline. The intensification of the T1-weighted MR-signal correlated with the increased volume density of heavily injured tubuli (R² = 0.77), with heavily damaged glomeruli (R² = 0.84) and with volume density of connective tissue (R² = 0.72). The changes in the MR signal intensity probably reflect the presence of an abundant proteinaceous material within the dilated nephrons and proliferation of the connective tissue. T₁-weighted MRI-is a valuable method for the in vivo screening of kidney and liver damage in rat models of intoxication with hepatotoxic and nephrotoxic agents, such as microcystins.  相似文献   

Landscape pattern changes over 25 years across a hotspot zone in southern Brazil     

Igor José Malfetoni Ferreira  Gabriel da Rocha Bragion  José Hilário Delconte Ferreira  Evanilde Benedito 《Southern Forests》2019,81(2):175-184

Forest fragmentation caused by human activities has many implications for natural landscapes, such as habitat reduction and the loss of biodiversity. This study investigated the temporal fragmentation process of forest remnants in a strongly agro-industrialised region in southern Brazil over 25 years. The studied watershed area hosts two important typologies of the Atlantic Forest biome as well as Quaternary remnants of the Brazilian Savanna biome, which are considered hotspots of biodiversity and reflect the intense process of forest fragmentation caused by Brazilian urban and agro-industrial development. Thus, studies encompassing multitemporal scales are paramount to understanding changes in forest patterns and are fundamental for trend predictions of landscape dynamics. To perform the calculation of the mean normalised difference vegetation index, Landsat satellite images from 1991 to 2016 were processed using SPRING® software. Subsequently, FRAGSTATS® software was used to calculate landscape metrics. A reduction in the number of forest fragments since 1991 was observed, with a maximum amount of 5 243 fragments in 1993 that declined to 4 015 fragments in 2016. Although the number of fragments in the watershed decreased, the mean area increased by 72.9% and the mean of the shape index increased from 1.3 in 1991 to 1.5 in 2016. In addition, there was a 64.7% increase in the edge density and a reduction of 35.6 m in the isolation between the nearest neighbours. The degree of isolation of the fragments underwent a process of expansion and reduction when compared to 1991, presenting results that support the hypothesis that the Atlantic Forest is in a process of stabilisation and forest restoration.  相似文献   

Presence–absence surveys of prey and their use in predicting leopard (Panthera pardus) densities: a case study from Armenia     

Igor G. KHOROZYAN  Alexander G. MALKHASYAN  Alexei V. ABRAMOV 《Integrative zoology》2008,3(4):322-332

It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not key threats are related to prey availability. Rugged terrain and low detection probabilities do not allow for the use of traditional prey count techniques in mountain areas. We used presence–absence occupancy modeling and camera‐trapping to estimate the abundance and densities of prey species and regression analysis to predict leopard (Panthera pardus) densities from estimated prey biomass in the mountains of the Nuvadi area, Meghri Ridge, southern Armenia. The prey densities were 12.94 ± 2.18 individuals km^?2 for the bezoar goat (Capra aegagrus), 6.88 ± 1.56 for the wild boar (Sus scrofa) and 0.44 ± 0.20 for the roe deer (Capreolus capreolus). The detection probability of the prey was a strong function of the activity patterns, and was highest in diurnal bezoar goats (0.59 ± 0.09). Based on robust regression, the estimated total ungulate prey biomass (720.37 ± 142.72 kg km^?2) can support a leopard density of 7. 18 ± 3.06 individuals 100 km^?2. The actual leopard density is only 0.34 individuals 100 km^?2 (i.e. one subadult male recorded over the 296.9 km²), estimated from tracking and camera‐trapping. The most plausible explanation for this discrepancy between predicted and actual leopard density is that poaching and disturbance caused by livestock breeding, plant gathering, deforestation and human‐induced wild fires are affecting the leopard population in Armenia.  相似文献   

Indicators of success for smart law enforcement in protected areas: A case study for Russian Amur tiger (Panthera tigris altaica) reserves          下载免费PDF全文

Michiel H. H. HÖTTE  Igor A. KOLODIN  Sergei L. BEREZNUK  Jonathan C. SLAGHT  Linda L. KERLEY  Svetlana V. SOUTYRINA  Galina P. SALKINA  Olga Y. ZAUMYSLOVA  Emma J. STOKES  Dale G. MIQUELLE 《Integrative zoology》2016,11(1):2-15

Although considerable conservation resources have been committed to develop and use law enforcement monitoring and management tools such as SMART, measures of success are ill‐defined and, to date, few reports detail results post‐implementation. Here, we present 4 case studies from protected areas with Amur tigers (Panthera tigris altaica) in Russia, in which indicators of success were defined and evaluated at each. The ultimate goal was an increase in tiger numbers to 1 individual/100 km² at each site. We predicted that improvements in law enforcement effectiveness would be followed by increases in prey numbers and, subsequently, tiger numbers. We used short‐term and long‐term indicators of success, including: (i) patrol team effort and effectiveness; (ii) catch per unit effort indicators (to measure reductions in threats); and (iii) changes in target species numbers. In addition to implementing a monitoring system, we focused on improving law enforcement management using an adaptive management process. Over 4 years, we noted clear increases in patrol effort and a partial reduction in threats. Although we did not detect clear trends in ungulate numbers, tiger populations remained stable or increased, suggesting that poaching of tigers may be more limiting than prey depletion. Increased effectiveness is needed before a clear reduction in threats can be noted, and more time is needed before detecting responses in target populations. Nonetheless, delineation of concrete goals and indicators of success provide a means of evaluating progress and weaknesses. Such monitoring should be a central component of law enforcement strategies for protected areas.  相似文献   

Loss of genetic variability in the captive stocks of tambaqui,Colossoma macropomum (Cuvier, 1818), at breeding centres in Brazil,and their divergence from wild populations          下载免费PDF全文

Jonas da Paz Aguiar  Paola Fabiana Fazzi Gomes  Igor Guerreiro Hamoy  Sidney Emanuel Batista dos Santos  Horacio Schneider  Iracilda Sampaio 《Aquaculture Research》2018,49(5):1914-1925

The loss of variability in farmed populations and the risks of interactions with wild populations support the need for the genetic monitoring of species farmed throughout the world. In Brazil, the tambaqui is the most widely farmed native fish species. Despite this, there are no data on the pedigree of the farmed stocks, and the potential for interactions with wild populations in the Amazon basin has raised concerns with regard to the genetic variability of these stocks. The present study analysed sequences of the mitochondrial Control Region and 12 microsatellites to characterize the genetic variability of seven historically important commercial tambaqui breeding centres located in four different regions of Brazil, and compared these sequences with those obtained from individuals collected from a wild population. High levels of genetic diversity were found in the wild population, whereas genetic diversity was reduced in both markers in most captive populations, except for the broodstock located near the Amazon River. High F_ST and D_EST indices were recorded between the wild population and most of the captive stocks analysed. The drastic reduction in genetic diversity found in most captive stocks and the difference between these stocks and the wild population may have been the result of the small size of the founding populations and the absence of breeding management. The renewal of the broodstocks and the application of breeding management techniques are recommended. In the Amazon region, in addition, the use of broodstocks that are genetically very different from local wild populations should be avoided.  相似文献