Stable Carbon and Nitrogen Isotopes in a Peat Profile Are Influenced by Early Stage Diagenesis and Changes in Atmospheric CO2 and N Deposition

In this study, we test whether the δ(13)C and δ(15)N in a peat profile are, respectively, linked to the recent dilution of atmospheric δ(13)CO(2) caused by increased fossil fuel combustion and changes in atmospheric δ(15)N deposition. We analysed bulk peat and Sphagnum fuscum branch C and N concentrations and bulk peat, S. fuscum branch and Andromeda polifolia leaf δ(13)C and δ(15)N from a 30-cm hummock-like peat profile from an Aapa mire in northern Finland. Statistically significant correlations were found between the dilution of atmospheric δ(13)CO(2) and bulk peat δ(13)C, as well as between historically increasing wet N deposition and bulk peat δ(15)N. However, these correlations may be affected by early stage kinetic fractionation during decomposition and possibly other processes. We conclude that bulk peat stable carbon and nitrogen isotope ratios may reflect the dilution of atmospheric δ(13)CO(2) and the changes in δ(15)N deposition, but probably also reflect the effects of early stage kinetic fractionation during diagenesis. This needs to be taken into account when interpreting palaeodata. There is a need for further studies of δ(15)N profiles in sufficiently old dated cores from sites with different rates of decomposition: These would facilitate more reliable separation of depositional δ(15)N from patterns caused by other processes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11270-011-1001-8) contains supplementary material, which is available to authorized users.     

Platelet-derived serotonin mediates liver regeneration

The liver can regenerate its volume after major tissue loss. In a mouse model of liver regeneration, thrombocytopenia, or impaired platelet activity resulted in the failure to initiate cellular proliferation in the liver. Platelets are major carriers of serotonin in the blood. In thrombocytopenic mice, a serotonin agonist reconstituted liver proliferation. The expression of 5-HT2A and 2B subtype serotonin receptors in the liver increased after hepatectomy. Antagonists of 5-HT2A and 2B receptors inhibited liver regeneration. Liver regeneration was also blunted in mice lacking tryptophan hydroxylase 1, which is the rate-limiting enzyme for the synthesis of peripheral serotonin. This failure of regeneration was rescued by reloading serotonin-free platelets with a serotonin precursor molecule. These results suggest that platelet-derived serotonin is involved in the initiation of liver regeneration.     

Diversity of kresoxim-methyl sensitivities in baseline populations of Venturia inaequalis

Several strobilurin fungicides inhibiting fungal respiration by binding to cytochrome b have been introduced recently. A mechanism of strobilurin resistance identified as active in several plant pathogenic fungi is based on the activation of alternative respiration. Thus far, respective studies have been restricted to single isolates of respective pathogens. Here, we report a study on 250 Venturia inaequalis baseline isolates to the strobilurin kresoxim-methyl having a broad sensitivity distribution characterized by a 50-fold difference in sensitivity of the most- and least-sensitive isolates. For the majority (62%) of these isolates, differences in sensitivity were not caused by the interference of alternative respiration with the full inhibitory potency of kresoxim-methyl. Rather, variable dose-responses with largely different degrees of inhibition achieved at a low dose of kresoxim-methyl were found to be responsible. For 38% of the baseline isolates, alternative respiration was already active during the stage of conidia germination. Activation of this pathway was, again, dependent on the strobilurin dose. Selection of sub-populations of isolates resisting low doses of kresoxim-methyl by multiple mechanisms and the recombination among isolates expressing such mechanisms singly can be expected to be slowed by an anti-resistance strategy based on high strobilurin doses. © 1999 Society of Chemical Industry     

Adaptive coding of reward value by dopamine neurons

It is important for animals to estimate the value of rewards as accurately as possible. Because the number of potential reward values is very large, it is necessary that the brain's limited resources be allocated so as to discriminate better among more likely reward outcomes at the expense of less likely outcomes. We found that midbrain dopamine neurons rapidly adapted to the information provided by reward-predicting stimuli. Responses shifted relative to the expected reward value, and the gain adjusted to the variance of reward value. In this way, dopamine neurons maintained their reward sensitivity over a large range of reward values.     

Use of thermography for high throughput phenotyping of tropical maize adaptation in water stress

In this study the suitability of thermal imaging for phenotyping was investigated as part of a breeding experiment carried out by the International Maize and Wheat Improvement Centre (CIMMYT) at Tlaltizapán experimental station in Mexico. Different subtropical maize genotypes with two replications were screened with respect to their tolerance to water stress. Thermal images of the canopy of 92 different maize genotypes were acquired on two different days in the time interval between anthesis and blister stages (grain filling 1), whereby each picture contained five plots of different genotypes and canopy temperatures calculated for each plot. Significantly, lower canopy temperatures were found in well-watered genotypes compared with water-stressed genotypes. Furthermore significant differences (p < 0.001) between genotypes under water stress were detected using thermal images. A close correlation (p < 0.01–0.001) between canopy temperature or modified Crop water stress index with NDVI and SPAD values was obtained. It may be concluded that genotypes better adapted to drought conditions exhibited lower temperatures.Thermography is a potentially promising method to accelerate the screening process and thereby enhance phenotyping for drought adaptation in maize.     

Inversion of a canopy reflectance model using hyperspectral imagery for monitoring wheat growth and estimating yield

Applications of hyperspectral remote sensing data to derive relevant properties for precision agriculture are described. Green leaf area index, fraction of senescent material and grain yield are retrieved from the hyperspectral data. Two sensors were used to obtain these data; the airborne visible/infrared imaging spectrometer AVIS and the space-borne compact high-resolution imaging spectrometer CHRIS; they show the applicability of the methods to different spatial scales. In addition, the bi-directional observation capability of the CHRIS sensor is used to derive information about the average leaf angle of the canopies which are used to link canopy structure with phenological development. Derivation of the canopy properties, green leaf area index and fraction of senescent material was done with the radiative transfer model, SLC (soil–leaf–canopy). The results were used as input into the crop growth model PROMET-V to calculate grain yield. Two years of data from the German research project preagro are presented.     

Food justice or food sovereignty? Understanding the rise of urban food movements in the USA

As world food and fuel prices threaten expanding urban populations, there is greater need for the urban poor to have access and claims over how and where food is produced and distributed. This is especially the case in marginalized urban settings where high proportions of the population are food insecure. The global movement for food sovereignty has been one attempt to reclaim rights and participation in the food system and challenge corporate food regimes. However, given its origins from the peasant farmers' movement, La Via Campesina, food sovereignty is often considered a rural issue when increasingly its demands for fair food systems are urban in nature. Through interviews with scholars, urban food activists, non-governmental and grassroots organizations in Oakland and New Orleans in the United States of America, we examine the extent to which food sovereignty has become embedded as a concept, strategy and practice. We consider food sovereignty alongside other dominant US social movements such as food justice, and find that while many organizations do not use the language of food sovereignty explicitly, the motives behind urban food activism are similar across movements as local actors draw on elements of each in practice. Overall, however, because of the different histories, geographic contexts, and relations to state and capital, food justice and food sovereignty differ as strategies and approaches. We conclude that the US urban food sovereignty movement is limited by neoliberal structural contexts that dampen its approach and radical framework. Similarly, we see restrictions on urban food justice movements that are also operating within a broader framework of market neoliberalism. However, we find that food justice was reported as an approach more aligned with the socio-historical context in both cities, due to its origins in broader class and race struggles.     

Einige Gedanken zuVavilovs Gesetz der homologen Reihen und zu den Ursachen homologer genetischer Variationen aus wissenschaftstheoretischer Sicht

Zusammenfassung Es wird die nach wie vor bestehende Gültigkeit des Gesetzes der homologen Reihen anhand von Ergebnissen der Zoologie und der konventionellen Pflanzenzüchtung dargestellt. Der Stand der Diskussionen über die Ursachen homologer Mutationen wird erörtert. Es wird der innere sachliche Zusammenhang des Gesetzes der homologen Reihen mit der Theorie der Gen- oder Mannigfaltigkeitszentren deutlich gemacht und Gültigkeit und Grenzen des Gesetzes der homologen Reihen im Lichte der sich abzeichnenden Ergebnisse und Aussichten der Gentechnologie diskutiert. Die erkenntnistheoretische Bedeutung des Gesetzes der homologen Reihen für Genetik und Züchtung wird mehrfach sichtbar gemacht.Im Unterschied zuVavilovs Genzentrentheorie, die in den letzten Jahren wiederholt kontrovers und kritisch diskutiert worden ist (Harlan 1971,Lehmann 1984), findet das vonVavilov im Juni 1920 auf dem III. Allrussischen Kongreß der Züchter erstmals formulierte und 1922 erstmals publizierte Gesetz der homologen Reihen (law of homologous series in variation) (Vavilov 1922) bis in die jüngste Zeit im großen und ganzen ungeteilte Zustimmung. Die Züchtung hat auf seiner Grundlage immer wieder erfolgreich gearbeitet, was die Gültigkeit der vonVavilov erkannten allgemeinen gesetzmäßigen Zusammenhänge bestätigt. AlsVavilov im Juni 1920 in Saratov das Gesetz der homologen Reihen erstmals öffentlich vortrug, wurde er enthusiastisch alsMendelejev der Biologie bezeichnet (Wessel 1986). Und in der Tat ermöglichte das Gesetz ähnlich dem Periodensystem der chemischen Elemente auf Grund bekannter Zusammenhänge die Voraussage der Existenz noch unbekannter Formen, die dann tatsächlich gefunden wurden. Der seinerzeit aufsehenerregende Erfolg der vonBaur auf der Grundlage des Gesetzes der homologen Reihen und auf der Grundlage derAntirrhinum-Forschung initiierten Süßlupinenzüchtung brachteVavilovs Gesetz allgemeine Anerkennung. Bekannt ist die Gültigkeit des Gesetzes nicht nur für Leguminosen, sondern auch für Gramineen und Cruciferen. Neben morphologischen Merkmalen gibt es homologe Wiederholungen auch bei physiologischen Merkmalen wie Variabilität, Widerstandsfähigkeit gegen niedere Temperaturen und Krankheiten, Länge der Vegetationszeit, photoperiodisches Reaktionsvermögen, Gehalt an primären Pflanzenstoffen (Kohlenhydrate, Eiweiße, Fette) und an sekundären Pflanzeninhaltsstoffen (Alkaloide, Glycoside, Gerbstoffe).

---

Vavilov's law of homologous series and the causes of homologous genetic variations — theoretical aspects

Summary The continuous validity of the law of homologous series is proved by the results of zoology and conventional plant breeding. An outline is given of the present state of discussion on the causes of homologous mutations. The relationship between the law of homologous series and the theory of gene centres (theory of genetic diversity) is shown. Validity and limits of the law of homologous series are discussed in the light of results and prospects of modern genetic engineering. The theoretical significance of the law of homologous series for genetics and plant breeding is illustrated by several examples.

---

:

, . . . . .

     

Application of an Air Ionization Device Using an Atmospheric Pressure Corona Discharge Process for Water Purification

Pesticides presently being discharged into the aquatic environment are not only toxic but also only partially biodegradable, they are not easily removed by conventional water treatment plants. Air ionization devices using an atmospheric pressure corona discharge process show great promise in improving degradation of chemical and biological contaminants in water purification plants. In order to assess the effectiveness of this air ionization apparatus, laboratory scale degradation experiments were carried out systematically in a bubble column reactor containing a variety of pesticides such as triazines, carbamates, phenyl urea derivates and chlorophenols relative to the addition of humic acid and inorganic chemicals as well as to pH variation. Chemical oxygen demand (COD) decreased with air ionization treatment and the rate of the biological oxygen demand related to this (BOD/COD) showed improved pesticide biodegradability. Changes in water toxicity were monitored by Daphnia- and Luminescence Bacteria tests. This novel water treatment process is shown to be a potent oxidation technique for persistent organic pollutants such as pesticides.