The lin-3/let-23 pathway mediates inductive signalling during male spicule development in Caenorhabditis elegans

During Caenorhabditis elegans male spicule development, four pairs of precursor cells respond to multiple positional cues and establish a pattern of fates that correlates with relative anterior-posterior cell position. One of the extracellular cues is provided by the F and U cells, which promote anterior fates. We show that the genes in the lin-3/let-23 signalling pathway required for hermaphrodite vulval induction also mediate this F/U signal. Reduction-of-function mutations in lin-3, let-23, sem-5, let-60 or lin-45 disrupt the fate of anterior cells. Likewise, activation of the pathway with ubiquitously produced signal results in posterior cells inappropriately adopting the anterior fates even in the absence of F and U. We have further used this genetic pathway to begin to understand how multiple positional cues are integrated to specify cell fate. We demonstrate that lin-15 acts in spicule development as it does in vulval induction, as a negative regulator of let-23 receptor activity. A second extracellular cue, from Y.p, also acts antagonistically to the lin-3/let-23 pathway. However, this signal is apparently integrated into the lin-3/let-23 pathway at some step after lin-45 raf and is thus functionally distinct from lin-15. We have also investigated the role of lin-12 in forming the anterior/posterior pattern of fates. A lin-12 gain-of-function defect is masked by redundant positional information from F and U

Health hazards of ultrafine metal and metal oxide powders

Study reveals that suggested threshold limit values are from two to fifty times lower than current recommended threshold limit values. Proposed safe limits of exposure to the ultrafine dusts are based on known toxic potential of various materials as determined in particle size ranges

EL PROBLEMA DEL OTRO Y LA ÉTICA. LA ANTROPOLOGÍA, LOS DERECHOS HUMANOS Y LA POLÍTICA

La cuestión a dilucidar es la ética que debe prevalecer en el desempeño antropológico, un tema que si bien tiene fuentes filosóficas subyace en la antropología de la manera en que ésta se acerca al problema de estudio. El texto que se presenta intenta ubicar una posible relación entre la ética, la antropología, los derechos humanos, y la política, frente al «problema del otro», con el fin de acercarlo al contexto mexicano desde los postulados de Enrique Dussel en su Introducción a una Filosofía Latinoamericana de la Liberación. ¿Qué relación existe entre ética y antropología? ¿Cuál debe ser la conducta ética del antropólogo? ¿Es posible una ética o debemos considerar muchas éticas dada la diversidad cultural? ¿Los derechos humanos son —como propuesta de valores— universales o esto es un imposible? ¿Existe una ética para la política frente a la diversidad? ABSTRACT This text explores the question of the ethics that should prevail in anthropological pursuits, a topic which, despite philosophical undertones, is an underlining issue in anthropology, particularly in the way in which it approaches the study problem. The article attempts to identify a possible relationship between ethics, anthropology, human rights and politics, in light of «the problem of the other,» with the purpose of positioning it within the Mexican context, based on the postulates of Enrique Dussel in his Introducción a una Filosofía Latinoamericana de la Liberación. What relation exists between ethics and anthropology? What should be considered ethical behavior of an anthropologist? Is just one ethic possible or must we consider several, given cultural diversity? Are human rights—as a proposal of values—universal, or is that impossible? Do ethics exist for politics, given this diversity

Poultry

Getting winter eggs from hens / D. C. Kennard and V. D. Chamberlin -- The protein requirements of growing pullets / R. M. Bethke, Paul R. Record and D. C. Kennard -- Coarse versus fine mash / D. C. Kennard -- Chicken vices / D. C. Kennard -- Tipping the beaks / D. C. Kennard -- Use of woven wire in poultry keeping -- Sun parlors for chick