Cryptochromes are flavoproteins that act as sensory blue light receptors in insects, plants, fungi, and bacteria. We have investigated a cryptochrome from the green alga Chlamydomonas reinhardtii with sequence homology to animal cryptochromes and (6-4) photolyases. In response to blue and red light exposure, this animal-like cryptochrome (aCRY) alters the light-dependent expression of various genes encoding proteins involved in chlorophyll and carotenoid biosynthesis, light-harvesting complexes, nitrogen metabolism, cell cycle control, and the circadian clock. Additionally, exposure to yellow but not far-red light leads to comparable increases in the expression of specific genes; this expression is significantly reduced in an acry insertional mutant. These in vivo effects are congruent with in vitro data showing that blue, yellow, and red light, but not far-red light, are absorbed by the neutral radical state of flavin in aCRY. The aCRY neutral radical is formed following blue light absorption of the oxidized flavin. Red illumination leads to conversion to the fully reduced state. Our data suggest that aCRY is a functionally important blue and red light-activated flavoprotein. The broad spectral response implies that the neutral radical state functions as a dark form in aCRY and expands the paradigm of flavoproteins and cryptochromes as blue light sensors to include other light qualities.

Cryptochromes are flavin-binding proteins that act as blue light receptors in bacteria, fungi, plants, and insects and are components of the circadian oscillator in mammals. Animal and plant cryptochromes are evolutionarily divergent, although the unicellular alga ( throughout) has both an animal-like cryptochrome and a plant cryptochrome (pCRY; formerly designated CPH1). Here, we show that the pCRY protein accumulates at night as part of a complex. Functional characterization of pCRY was performed based on an insertional mutant that expresses only 11% of the wild-type pCRY level. The mutant is defective for central properties of the circadian clock. In the mutant, the period is lengthened significantly, ultimately resulting in arrhythmicity, while blue light-based phase shifts show large deviations from what is observed in wild-type cells. We also show that pCRY is involved in gametogenesis in pCRY is down-regulated in pregametes and gametes, and in the mutant, there is altered transcript accumulation under blue light of the strictly light-dependent, gamete-specific gene pCRY acts as a negative regulator for the induction of mating ability in the light and for the loss of mating ability in the dark. Moreover, pCRY is necessary for light-dependent germination, during which the zygote undergoes meiosis that gives rise to four vegetative cells. In sum, our data demonstrate that pCRY is a key blue light receptor in that is involved in both circadian timing and life cycle progression.

Cryptochromes are known as flavin-binding blue light receptors in bacteria, fungi, plants, and insects. The animal-like cryptochrome (aCRY) of the green alga has extended our view on cryptochromes, because it responds also to other wavelengths of the visible spectrum, including red light. Here, we have investigated if aCRY is involved in the regulation of the sexual life cycle of, which is controlled by blue and red light at the steps of gametogenesis along with its restoration and germination. We show that aCRY is differentially expressed not only during the life cycle but also within the cell as part of the soluble and/or membrane-associated protein fraction. Moreover, localization of aCRY within the algal cell body varies between vegetative cells and the different cell types of gametogenesis. aCRY is significantly (early day) or to a small extent (late night) enriched in the nucleus in vegetative cells. In pregametes, gametes and dark-inactivated gametes, aCRY is localized over the cell body. aCRY plays an important role in the sexual life cycle of : It controls the germination of the alga, under which the zygote undergoes meiosis, in a positive manner, similar to the regulation by the blue light receptors phototropin and plant cryptochrome (pCRY). However, aCRY acts in combination with pCRY as a negative regulator for mating ability as well as for mating maintenance, opposite to the function of phototropin in these processes.

Cryptochromes (CRYs) are flavoproteins that are known as blue light photoreceptors in many organisms. Recently, genome sequences from a variety of algae became available. Functional characterizations of animal-like CRYs from Oestreococcus tauri, Chlamydomonas reinhardtii and Phaeodactylum tricornutum highlighted novel functions and properties. As arising from studies in fungi, certain algal CRYs of the "cryptochrome photolyase family" (PtCPF1, OtCPF1) have dual or even triple functions. They are involved in blue light perception and/or in the circadian clock and are able to repair DNA damages. On the other hand, the animal-like aCRY from C. reinhardtii is not only acting as sensory blue light- but also as sensory red light receptor thus expanding our current view of flavoproteins in general and CRYs in particular. The observed broad spectral response points to the neutral radical state of flavin, which is assumed to be the dark form in aCRY in contrast to the plant CRYs.

Kurzfassung Aufgrund des wachsenden Einsatzes von Prozessen, in denen Mensch und Roboter zusammen und ohne Schutzzaun interagieren, wächst die Zahl der zu programmierenden sicheren Roboter in der Industrie. Ziel dieser Arbeit ist es, ein Prinzip der einfachen Programmierung zu zeigen, sodass auch Facharbeiter ohne große Programmierkenntnisse eine Mensch-Roboter-Kollaboration (MRK) erstellen können. Es wird ein Baukastenprinzip vorgestellt, mit dem Mensch-Roboter-Interaktionen durch verschieden zusammengesetzte Bausteine aufgebaut beziehungsweise programmiert werden können. Zum Schluss verdeutlichen zwei Beispiele an einem Leichtbauroboter das ausgeführte Prinzip der Programmierung.