Conidiation in Neurospora crassa: vegetative reproduction by a model fungus

Asexual development, conidiation, in the filamentous fungus Neurospora crassa is a simple developmental process that starts with the growth of aerial hyphae. Then, the formation of constrictions and subsequent maturation gives rise to the mature conidia that are easily dispersed by air currents. Conidiation is regulated by environmental factors such as light, aeration and nutrient limitation, and by the circadian clock. Different regulatory proteins acting at different stages of conidiation have been described. The role of transcription factors such as FL, and components of signal transduction pathways such as the cAMP phosphodiesterase ACON-2 suggest a complex interplay between differential transcription and signal transduction pathways. Comparisons between the molecular basis of conidiation in N. crassa and other filamentous fungi will help to identify common regulatory elements

Fungal photobiology: a synopsis

Fungi respond and adapt to many environmental signals including light. The photobiology of fungi has been extensively investigated, but in recent years the identification of the first fungal photoreceptor, WC-1 in the ascomycete Neurospora crassa, and the discovery that similar photoreceptors are required for photoreception in other ascomycete, basidiomycete and zygomycete fungi has allowed the molecular characterization of light reception and the early steps of signal transduction in a number of model fungi. This contribution is based on presentations made at the Special Interest Group Meeting on “Fungal Photobiology” held during IMC9. The contributions summarize the current status of fungal photobiology in Aspergillus nidulans, Neurospora crassa, Mucor circinelloides, and Coprinopsis cinerea

Cysteinyl-tRNA synthetase is a direct descendant of the first aminoacyl-tRNA synthetase

AbstractThe gene encoding the cysteinyl-tRNA synthetase of E. coli was cloned from an E. coli genomic library made in λ2761, a lambda vector which can integrate and which carries a chloramphenicol resistance gene. A thermosensitive cysS mutant of E. coli was lysogenised and chloramphenicol-resistant colonies able to grow at 42°C were selected to isolate phages containing the wild-type cysS gene. The sequence of the gene was determined. It codes for a 461 amino-acid protein and includes the sequences HIGH and KMSK known to be involved in the ATP and TRNA binding respectively of class I synthetases. The cysteinyl enzyme has segments in common with the cytoplasmic leucyl-tRNA synthetase of Neurospora crassa, the tryptophanyl-tRNA synthetase of Bacillus stearothermophilus, and the phenylalanyl-tRNA synthetase of Saccharomyces cerevisiae. Sequence comparisons show that the amino end of the cysteinyl-tRNA synthetase has similarities with prokaryotic elongation factors Tu; this region is close to the equivalent acceptor binding domain of the glutaminyl-tRNa synthetase of E. coli. There is a further similarity with the seryl enzyme (a class II enzyme) which has led us to propose that both classes had a common origin and that this was the ancestor of the cysteinyl-tRNA synthetase

A glimpse into the basis of vision in the kingdom Mycota

Virtually all organisms exposed to light are capable of sensing this environmental signal. In recent years the photoreceptors that mediate the ability of fungi to " see" have been identified in diverse species, and increasingly characterized. The small sizes of fungal genomes and ease in genetic and molecular biology manipulations make this kingdom ideal amongst the eukaryotes for understanding photosensing. The most widespread and conserved photosensory protein in the fungi is White collar 1 (WC-1), a flavin-binding photoreceptor that functions with WC-2 as a transcription factor complex. Other photosensory proteins in fungi include opsins, phytochromes and cryptochromes whose roles in fungal photobiology are not fully resolved and their distribution in the fungi requires further taxon sampling. Additional unknown photoreceptors await discovery. This review discusses the effects of light on fungi and the evolutionary processes that may have shaped the ability of species to sense and respond to this signal.United States National Institutes of Health K22 AI073917National Science Foundation MCB-0920581Ministerio de Ciencia e Innovación BIO2009-12486Junta de Andalucía P06-CVI-01650, P09-CVI-502

La solución de controversias entre estados en los tratados de libre comercio

Los tratados de libre comercio no apuntan a crear sistemas burocráticos de integración, sino marcos legales que permitan el flujo transfronterizo de bienes y capitales. En ese sentido, al carecer de una estructura institucional permanente, requieren dotarse de sistemas de solución de controversias capaces de resolver los problemas que se presenten en el comercio entre los particulares, y también aquellos que se deriven de los actos legales y administrativos de los Estados partes, y que puedan impactar negativamente en el comercio entre ellos. Los sistemas de solución de controversias proponen mecanismos ágiles, fiables e imparciales que permitan resolver los desacuerdos y eviten que el cumplimiento de los tratados se vea perjudicado por el surgimiento de contenciosos que paralicen su aplicación y frenen el desarrollo de los aspectos sustantivos del tratado. En ese sentido, el artículo examina y compara los mecanismos previstos en algunos tratados de libre comercio acordados a nivel regiona

Diagnóstico: el derecho internacional, su eficacia y su relación con el derecho interno

En la presente entrevista, se abarca la forma en que el Derecho Internacional se hace realidad y cómo es que éste logra permanecer independiente de los avatares políticos mundiales. El énfasis, en este caso, se dará sobre el Consejo de Seguridad de las Naciones Unidas y el papel que éste cumple, o podría cumplir, en el mantenimiento de la paz y el orden mundiales

Robust Pose Control of Robot Manipulators Using Conformal Geometric Algebra

A controller, based on sliding mode control, is proposed for the n-link robotic manipulator pose tracking problem. The point pair (a geometric entity expressed in geometric algebra) is used to represent position and orientation of the end-effector of a manipulator. This permits us to express the direct and differential kinematics of the endeffector of the manipulator in a simple and compact way. For the control, a sliding mode controller is designed with the following properties: robustness against perturbations and parameter variations, finite time convergence, and easy implementation. Finally, the application, of the proposed controller in a 6 DOF robotic manipulator is presented via simulation.Consejo Nacional de Ciencia y Tecnologí

Multi-mode Flight Sliding Mode Control System for a Quadrotor

There is a wide range of applications for unmanned aerial vehicles that requires the capability of having several and robust flight controllers available. This paper presents the main framework of a multimode flight control system for a quadrotor based on the super twisting control algorithm. The design stages for the four flight control modes encompassing manual, altitude, GPS fixed and autonomous mode are presented. The stability proof for each flight mode is carried out by means of Lyapunov functions while the stability analysis for the complete system, when a transition from one mode to another occurs, is demonstrated using the switching nonlinear systems theory. The performance of the proposed framework is demonstrated in a simulation study taking into account external disturbances.ITESO, A.C.CINVESTAV-IP