Temporal dynamics of competitive fertilization in social groups of red junglefowl (Gallus gallus) shed new light on avian sperm competition

Studies of birds have made a fundamental contribution to elucidating sperm competition processes, experimentally demonstrating the role of individual mechanisms in competitive fertilization. However, the relative importance of these mechanisms and the way in which they interact under natural conditions remain largely unexplored. Here, we conduct a detailed behavioural study of freely mating replicate groups of red junglefowl, Gallus gallus, to predict the probability that competing males fertilize individual eggs over the course of 10-day trials. Remating frequently with a female and mating last increased a male's probability of fertilization, but only for eggs ovulated in the last days of a trial. Conversely, older males, and those mating with more polyandrous females, had consistently lower fertilization success. Similarly, resistance to a male's mating attempts, particularly by younger females, reduced fertilization probability. After considering these factors, male social status, partner relatedness and the estimated state of male extragonadal sperm reserves did not predict sperm competition outcomes. These results shed new light on sperm competition dynamics in taxa such as birds, with prolonged female sperm storage and staggered fertilizations. This article is part of the theme issue 'Fifty years of sperm competition'

América Latina. Los derechos y las prácticas ciudadanas a la luz de los movimientos populares

A partir, fundamentalmente, de los análisis de caso y los datos que ha sistematizado el Observatorio Social de América Latina (OSAL), nuestra propuesta gira en torno a dos preguntas centrales: ¿qué características presenta la noción de ciudadanía en las luchas sociales latinoamericanas recientes?, y ¿qué importancia adquiere dicha dimensión para la consecución de un propósito democrático? Buscando responder ambas, hemos dividido la exposición en tres apartados. En el primero se exploran los elementos que han favorecido el reposicionamiento de la noción de ciudadanía, dentro del horizonte y discurso de las movilizaciones que a partir del año 2000 han aparecido en distintos puntos del subcontinente. En el segundo, se examinan las características más relevantes que desde nuestro punto de vista hilvanan su diversidad. Y, finalmente, en el último se desarrollan las razones por las cuales consideramos que la noción de ciudadanía ocupa un lugar estratégico en la lucha social latinoamericana de este inicio de milenio.Presentación | 9 Lucha social y derechos ciudadanos en América Latina Margarita Favela Gavia y Diana Guillén | 21 Conflictos y tensiones en torno del Estado ampliado en América Latina: Brasil y México entre la crisis orgánica del Estado y el problema de la hegemonía Lucio Oliver | 51 Movimiento-partido: el caso del Movimiento de los Trabajadores sin Tierra (MST) en Brasil Adelita Neto Carleial | 81 Seguridad alimentaria y diseño de nuevos espacios públicos en Brasil Elza Maria Franco Braga | 111 Democracia y ciudadanía en el movimiento lopezobradorista Carlos Figueroa Ibarra y Octavio H. Moreno | 129 Venciendo el miedo: retoños de movimientos sociales en el contexto de la recuperación democrática en Perú (2000-2006) Fabiola Escárzaga | 155 Reflexiones sobre la democracia y el significado de un gobierno de los movimientos sociales en Bolivia Dunia Mokrani Chávez | 191 Entre la izquierda partidista y la izquierda social: el movimiento étnico maya y las opciones político-partidistas en Guatemala Luis Fernando Mack, Máximo Ba Tiul e Ivonne Solórzano | 215 Movimiento social y proceso político en Haití (1986-2006) Alejandro Álvarez Martínez | 24

Multiuser Cognitive Radio Networks: An Information Theoretic Perspective

Achievable rate regions and outer bounds are derived for three-user interference channels where the transmitters cooperate in a unidirectional manner via a noncausal message-sharing mechanism. The three-user channel facilitates different ways of message-sharing between the primary and secondary (or cognitive) transmitters. Three natural extensions of unidirectional message-sharing from two users to three users are introduced: (i) Cumulative message sharing; (ii) primary-only message sharing; and (iii) cognitive-only message sharing. To emphasize the notion of interference management, channels are classified based on different rate-splitting strategies at the transmitters. Standard techniques, superposition coding and Gel'fand-Pinsker's binning principle, are employed to derive an achievable rate region for each of the cognitive interference channels. Simulation results for the Gaussian channel case are presented; they enable visual comparison of the achievable rate regions for different message-sharing schemes along with the outer bounds. These results also provide useful insights into the effect of rate-splitting at the transmitters, which aids in better interference management at the receivers.Comment: 50 pages, 15 figures, submitted to IEEE Transactions on Information Theor

Investigations into a putative role for the novel BRASSIKIN pseudokinases in compatible pollen-stigma interactions in Arabidopsis thaliana.

BACKGROUND: In the Brassicaceae, the early stages of compatible pollen-stigma interactions are tightly controlled with early checkpoints regulating pollen adhesion, hydration and germination, and pollen tube entry into the stigmatic surface. However, the early signalling events in the stigma which trigger these compatible interactions remain unknown. RESULTS: A set of stigma-expressed pseudokinase genes, termed BRASSIKINs (BKNs), were identified and found to be present in only core Brassicaceae genomes. In Arabidopsis thaliana Col-0, BKN1 displayed stigma-specific expression while the BKN2 gene was expressed in other tissues as well. CRISPR deletion mutations were generated for the two tandemly linked BKNs, and very mild hydration defects were observed for wild-type Col-0 pollen when placed on the bkn1/2 mutant stigmas. In further analyses, the predominant transcript for the stigma-specific BKN1 was found to have a premature stop codon in the Col-0 ecotype, but a survey of the 1001 Arabidopsis genomes uncovered three ecotypes that encoded a full-length BKN1 protein. Furthermore, phylogenetic analyses identified intact BKN1 orthologues in the closely related outcrossing Arabidopsis species, A. lyrata and A. halleri. Finally, the BKN pseudokinases were found to be plasma-membrane localized through the dual lipid modification of myristoylation and palmitoylation, and this localization would be consistent with a role in signaling complexes. CONCLUSION: In this study, we have characterized the novel Brassicaceae-specific family of BKN pseudokinase genes, and examined the function of BKN1 and BKN2 in the context of pollen-stigma interactions in A. thaliana Col-0. Additionally, premature stop codons were identified in the predicted stigma specific BKN1 gene in a number of the 1001 A. thaliana ecotype genomes, and this was in contrast to the out-crossing Arabidopsis species which carried intact copies of BKN1. Thus, understanding the function of BKN1 in other Brassicaceae species will be a key direction for future studies