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Light sensing is very important for organisms in all biological kingdoms to adapt to changing environmental conditions. It was discovered recently that plant-like phytochrome is involved in light sensing in the filamentous fungus Aspergillus nidulans[1]. Here, we show that phytochrome (FphA) is part of a protein complex containing LreA (WC-1) and LreB (WC-2) [2, 3], two central components of the Neurospora crassa blue-light-sensing system. We found that FphA represses sexual development and mycotoxin formation, whereas LreA and LreB stimulate both. Surprisingly, FphA interacted with LreB and with VeA, another regulator involved in light sensing and mycotoxin biosynthesis. LreB also interacted with LreA. All protein interactions occurred in the nucleus, despite cytoplasmic subfractions of the proteins. Whereas the FphA-VeA interaction was dependent on the presence of the linear tetrapyrrole in FphA, the interaction between FphA and LreB was chromophore independent. These results suggest that morphological and physiological differentiations in A. nidulans are mediated through a network consisting of FphA, LreA, LreB, and VeA acting in a large protein complex in the nucleus, sensing red and blue light.

Feature-oriented software development (FOSD) is a paradigm for the construction, customization, and synthesis of large-scale software systems. In this survey, we give an overview and a personal perspective on the roots of FOSD, connections to other software development paradigms, and recent developments in this field. Our aim is to point to connections between different lines of research and to identify open issues.

Features express the variabilities and commonalities among programs in a software product line (SPL). A feature model defines the valid combinations of features, where each combination corresponds to a program in an SPL. SPLs and their feature models evolve over time. We classify the evolution of a feature model via modifications as refactorings, specializations, generalizations, or arbitrary edits. We present an algorithm to reason about feature model edits to help designers determine how the program membership of an SPL has changed. Our algorithm takes two feature models as input (before and after edit versions), where the set of features in both models are not necessarily the same, and it automatically computes the change classification. Our algorithm is able to give examples of added or deleted products and efficiently classifies edits to even large models that have thousands of features.

Light is one of the most important environmental factors for orientation of almost all organisms on Earth. Whereas light sensing is of crucial importance in plants to optimize light-dependent energy conservation, in nonphotosynthetic organisms, the synchronization of biological clocks to the length of a day is an important function. Filamentous fungi may use the light signal as an indicator for the exposure of hyphae to air and adapt their physiology to this situation or induce morphogenetic pathways. Although a yes/no decision appears to be sufficient for the light-sensing function in fungi, most species apply a number of different, wavelength-specific receptors. The core of all receptor types is a chromophore, a low-molecular-weight organic molecule, such as flavin, retinal, or linear tetrapyrrols for blue-, green-, or red-light sensing, respectively. Whereas the blue-light response in fungi is one of the best-studied light responses, all other light-sensing mechanisms are less well studied or largely unknown. The discovery of phytochrome in bacteria and fungi in recent years not only advanced the scientific field significantly, but also had great impact on our view of the evolution of phytochrome-like photoreceptors.