Towards Comprehensive Foundations of Computational Intelligence

Abstract. Although computational intelligence (CI) covers a vast variety of different methods it still lacks an integrative theory. Several proposals for CI foundations are discussed: computing and cognition as compression, meta-learning as search in the space of data models, (dis)similarity based methods providing a framework for such meta-learning, and a more general approach based on chains of transformations. Many useful transformations that extract information from features are discussed. Heterogeneous adaptive systems are presented as particular example of transformation-based systems, and the goal of learning is redefined to facilitate creation of simpler data models. The need to understand data structures leads to techniques for logical and prototype-based rule extraction, and to generation of multiple alternative models, while the need to increase predictive power of adaptive models leads to committees of competent models. Learning from partial observations is a natural extension towards reasoning based on perceptions, and an approach to intuitive solving of such problems is presented. Throughout the paper neurocognitive inspirations are frequently used and are especially important in modeling of the higher cognitive functions. Promising directions such as liquid and laminar computing are identified and many open problems presented.

Shoot-to-root mobile polypeptides involved in systemic regulation of nitrogen acquisition

Plants uptake nitrogen (N) from the soil mainly in the form of nitrate. However, nitrate is often distributed heterogeneously in natural soil. Plants, therefore, have a systemic long-distance signalling mechanism by which N starvation on one side of the root leads to a compensatory N uptake on the other N-rich side1,2. This systemic N acquisition response is triggered by a root-to-shoot mobile peptide hormone, C-TERMINALLY ENCODED PEPTIDE (CEP), originating from the N-starved roots3,4, but the molecular nature of the descending shoot-to-root signal remains elusive. Here, we show that phloem-specific polypeptides that are induced in leaves upon perception of root-derived CEP act as descending long-distance mobile signals translocated to each root. These shoot-derived polypeptides, which we named CEP DOWNSTREAM 1 (CEPD1) and CEPD2, upregulate the expression of the nitrate transporter gene NRT2.1 in roots specifically when nitrate is present in the rhizosphere. Arabidopsis plants deficient in this pathway show impaired systemic N acquisition response accompanied with N-deficiency symptoms. These fundamental mechanistic insights should provide a conceptual framework for understanding systemic nutrient acquisition responses in plants.journal articl

Iron deficiency-mediated stress regulation of four subgroup Ib BHLH genes in Arabidopsis thaliana

Wang H-Y, Klatte M, Jakoby M, Baeumlein H, Weisshaar B, Bauer P. Iron deficiency-mediated stress regulation of four subgroup Ib BHLH genes in Arabidopsis thaliana. Planta. 2007;226(4):897-908

Metabolic changes in iron-stressed dicotyledonous plants

The response to iron deficiency stress in dicotyledonous plants is by far more complex than the simple activation of the reduction-based mechanism. In most of the Strategy I plants studied so far there is an associated increase in the activity of a plasma membrane H+-ATPase which actively extrudes the protons necessary both for decreasing the rhizospheric pH and generating the electrochemical proton gradient needed to drive ion uptake. Along with these activities, localised on the root plasma membrane, it has been found that metabolism is involved in sustaining the production of reducing equivalents [NAD(P)H] and ATP. Many processes (glycolysis, respiration, etc.) are increased to efficiently sustain the response to iron depletion. In particular, the activity of phosphoenolpyruvate carboxylase is increased several fold. These increases could be linked to the production of substrates for the ferric chelate reductases and H+-ATPase activities, generation of H+ for the cytosolic pHstat and organic acids. The activation of all these processes makes plants more efficient in the acquisition of iron