Mitigation and Adaptation Strategies – Organic Agriculture

This psoter presents information on the following - The concept of organic farming in the context of climate change - Carbon sequestration on organic farms - Consequences of an area-wide conversion to organic agricultur

Increased copy number for methylated maternal 15q duplications leads to changes in gene and protein expression in human cortical samples

<p>Abstract</p> <p>Background</p> <p>Duplication of chromosome 15q11-q13 (dup15q) accounts for approximately 3% of autism cases. Chromosome 15q11-q13 contains imprinted genes necessary for normal mammalian neurodevelopment controlled by a differentially methylated imprinting center (imprinting center of the Prader-Willi locus, PWS-IC). Maternal dup15q occurs as both interstitial duplications and isodicentric chromosome 15. Overexpression of the maternally expressed gene <it>UBE3A </it>is predicted to be the primary cause of the autistic features associated with dup15q. Previous analysis of two postmortem dup15q frontal cortical samples showed heterogeneity between the two cases, with one showing levels of the GABA_Areceptor genes, <it>UBE3A </it>and <it>SNRPN </it>in a manner not predicted by copy number or parental imprint.</p> <p>Methods</p> <p>Postmortem human brain tissue (Brodmann area 19, extrastriate visual cortex) was obtained from 8 dup15q, 10 idiopathic autism and 21 typical control tissue samples. Quantitative PCR was used to confirm duplication status. Quantitative RT-PCR and Western blot analyses were performed to measure 15q11-q13 transcript and protein levels, respectively. Methylation-sensitive high-resolution melting-curve analysis was performed on brain genomic DNA to identify the maternal:paternal ratio of methylation at PWS-IC.</p> <p>Results</p> <p>Dup15q brain samples showed a higher level of PWS-IC methylation than control or autism samples, indicating that dup15q was maternal in origin. <it>UBE3A </it>transcript and protein levels were significantly higher than control and autism in dup15q, as expected, although levels were variable and lower than expected based on copy number in some samples. In contrast, this increase in copy number did not result in consistently increased <it>GABRB3 </it>transcript or protein levels for dup15q samples. Furthermore, <it>SNRPN </it>was expected to be unchanged in expression in dup15q because it is expressed from the single unmethylated paternal allele, yet <it>SNRPN </it>levels were significantly reduced in dup15q samples compared to controls. PWS-IC methylation positively correlated with <it>UBE3A </it>and <it>GABRB3 </it>levels but negatively correlated with <it>SNRPN </it>levels. Idiopathic autism samples exhibited significantly lower <it>GABRB3 </it>and significantly more variable <it>SNRPN </it>levels compared to controls.</p> <p>Conclusions</p> <p>Although these results show that increased <it>UBE3A</it>/UBE3A is a consistent feature of dup15q syndrome, they also suggest that gene expression within 15q11-q13 is not based entirely on copy number but can be influenced by epigenetic mechanisms in brain.</p

Thermodynamics of adiabatic feedback control

We study adaptive control of classical ergodic Hamiltonian systems, where the controlling parameter varies slowly in time and is influenced by system's state (feedback). An effective adiabatic description is obtained for slow variables of the system. A general limit on the feedback induced negative entropy production is uncovered. It relates the quickest negentropy production to fluctuations of the control Hamiltonian. The method deals efficiently with the entropy-information trade off.Comment: 6 pages, 1 figur

Saturation of a spin 1/2 particle by generalized Local control

We show how to apply a generalization of Local control design to the problem of saturation of a spin 1/2 particle by magnetic fields in Nuclear Magnetic Resonance. The generalization of local or Lyapunov control arises from the fact that the derivative of the Lyapunov function does not depend explicitly on the control field. The second derivative is used to determine the local control field. We compare the efficiency of this approach with respect to the time-optimal solution which has been recently derived using geometric methods.Comment: 12 pages, 4 figures, submitted to new journal of physics (2011

Traveling wave solutions for a predator-prey system with Sigmoidal response function

We study the existence of traveling wave solutions for a diffusive predator-prey system. The system considered in this paper is governed by a Sigmoidal response function which is more general than those studied previously. Our method is an improvement to the original method introduced in the work of Dunbar \cite{Dunbar1,Dunbar2}. A bounded Wazewski set is used in this work while unbounded Wazewski sets were used in \cite{Dunbar1,Dunbar2}. The existence of traveling wave solutions connecting two equilibria is established by using the original Wazewski's theorem which is much simpler than the extended version in Dunbar's work

The potential of parasitoid Hymenoptera as bioindicators of arthropod diversity in agricultural grasslands

1. As measuring biodiversity in its entirety is impractical, there is a need for bioindicators. This study tested the hypothesis that parasitoid Hymenoptera are potential bioindicators that provide a useful means to assess the wider biodiversity of arthropod populations in agro-ecosystems. There are a range of theoretical arguments to support such a claim, including the high trophic position of these taxa within the arthropod communities in which they occur, and the unique nature of their biological relationships with the majority of terrestrial arthropod groups. 2. A survey of 48 commercial farms was conducted and Generalized Linear Models used to investigate relationships between six taxa—parasitoid Hymenoptera, Coleoptera, Hemiptera, Diptera, Araneae and plants (species richness and sward height)—in agricultural grasslands. As well as relationships between these groups, the relationship of each individual group to the overall biodiversity of all other arthropod groups was explored. 3. Both abundance (r2 = 0·58) and taxon richness (r2 = 0·54) of parasitoid Hymenoptera had stronger relationships with overall arthropod taxon richness than any other arthropod group investigated. Parasitoid abundance also had a positive relationship with species richness of Coleoptera (r2 = 0·23) and Hemiptera (r2 = 0·47). 4. An historical data set demonstrated how the relationship between parasitoid abundance and overall arthropod taxon richness changes over the growing season. July, when the relationship was strongest, is potentially the most useful time to sample. 5. For use in routine monitoring, it is important that an effort be made to understand the seasonal influence on the relationship in the context being studied. Equal sampling effort must be made for all sites being compared and sites should be sampled as close together in the season as is possible. 6. Synthesis and applications. We show that, within agricultural grasslands, both the abundance and taxon richness of parasitoid Hymenoptera are more closely related with overall arthropod diversity than any other arthropod group investigated. The use of parasitoid abundance provides a simple and practicable monitoring tool for tracking change in wider arthropod diversity in agro-ecosystems