Crosstalks between Myo-Inositol Metabolism, Programmed Cell Death and Basal Immunity in Arabidopsis

BACKGROUND: Although it is a crucial cellular process required for both normal development and to face stress conditions, the control of programmed cell death in plants is not fully understood. We previously reported the isolation of ATXR5 and ATXR6, two PCNA-binding proteins that could be involved in the regulation of cell cycle or cell death. A yeast two-hybrid screen using ATXR5 as bait captured AtIPS1, an enzyme which catalyses the committed step of myo-inositol (MI) biosynthesis. atips1 mutants form spontaneous lesions on leaves, raising the possibility that MI metabolism may play a role in the control of PCD in plants. In this work, we have characterised atips1 mutants to gain insight regarding the role of MI in PCD regulation. METHODOLOGY/PRINCIPAL FINDINGS: - lesion formation in atips1 mutants depends of light intensity, is due to PCD as evidenced by TUNEL labelling of nuclei, and is regulated by phytohormones such as salicylic acid - MI and galactinol are the only metabolites whose accumulation is significantly reduced in the mutant, and supplementation of the mutant with these compounds is sufficient to prevent PCD - the transcriptome profile of the mutant is extremely similar to that of lesion mimic mutants such as cpr5, or wild-type plants infected with pathogens. CONCLUSION/SIGNIFICANCE: Taken together, our results provide strong evidence for the role of MI or MI derivatives in the regulation of PCD. Interestingly, there are three isoforms of IPS in Arabidopsis, but AtIPS1 is the only one harbouring a nuclear localisation sequence, suggesting that nuclear pools of MI may play a specific role in PCD regulation and opening new research prospects regarding the role of MI in the prevention of tumorigenesis. Nevertheless, the significance of the interaction between AtIPS1 and ATXR5 remains to be established

RNA preservation of Antarctic marine invertebrates

Fifteen species of marine invertebrate commonly occurring in the near-shore environment of Rothera base, Antarctica, were used to test tissue sample storage protocols with regard to preservation of RNA integrity. After animal collection, the tissues were either immediately extracted for RNA or stored at -80C after having been, either directly flash frozen in liquid nitrogen or preserved in a commercial RNA storage solution, for extraction in the UK. In four cases, direct flash freezing produced enhanced RNA integrity compared with samples in the commercial storage solution. A subset of samples were further tested for the preferred temperature of storage in the commercial reagent. RNA integrity was well preserved at both ?4 and -20C over periods of 2 months, but degradation was rapid in tissues stored at room temperature. Eight out of the fifteen species only produced a single ribosomal band on gel electrophoresis. This survey provides a guide for tissue transport of Polar cold water marine invertebrates. Keywords Tissue preservation Tissue transport 28 s ribosomal RNA Echinoderms Molluscs Introduction RNA preservation is sometimes problematic in non-model species but this is particularly the case when dealing with environmental species. Logistical issues often surround the ability to effectively preserve field-collected samples for RNA analyses. Whilst rapid flash freezing in liquid nitrogen generally solves this problem, it is not often available because of the remote nature of the work. Even when such a facility is available on site at a field station, it usually cannot be transported to the actual, more remote specimen collection site. Also, -80C storage may not be possible during transportation from the field site to the main research institute, often thousands of miles away. Antarctic specimens have the additional issue of operating at temperatures that most species would consider cold and hence cool stow is less effective at reducing tissue degradation than with, for example, those taken from mammalian species. Hence, we decided to carry out a study of effective storage protocols for the most common invertebrates found in the near-shore marine environment in Marguerite Bay close to Rothera research station, Antarctica

Scalable multiagent learning through indirect encoding of policy geometry

Multiagent systems present many challenging, real-world problems to artificial intelligence. Because it is difficult to engineer the behaviors of multiple cooperating agents by hand, multiagent learning has become a popular approach to their design. While there are a variety of traditional approaches to multiagent learning, many suffer from increased computational costs for large teams and the problem of reinvention (that is, the inability to recognize that certain skills are shared by some or all team member). This paper presents an alternative approach to multiagent learning called multiagent HyperNEAT that represents the team as a pattern of policies rather than as a set of individual agents. The main idea is that an agent\u27s location within a canonical team layout (which can be physical, such as positions on a sports team, or conceptual, such as an agent\u27s relative speed) tends to dictate its role within that team. This paper introduces the term policy geometry to describe this relationship between role and position on the team. Interestingly, such patterns effectively represent up to an infinite number of multiagent policies that can be sampled from the policy geometry as needed to allow training very large teams or, in some cases, scaling up the size of a team without additional learning. In this paper, multiagent HyperNEAT is compared to a traditional learning method, multiagent Sarsa(λ), in a predator-prey domain, where it demonstrates its ability to train large teams. © 2013 Springer-Verlag Berlin Heidelberg