Polygenic and major-locus contributions to sexual maturation timing in Atlantic salmon

Sexual maturation timing is a life-history trait central to the balance between mortality and reproduction. Maturation may be triggered when an underlying compound trait, called liability, exceeds a threshold. In many different species and especially fishes, this liability is approximated by growth and body condition. However, environmental vs. genetic contributions either directly or via growth and body condition to maturation timing remain unclear. Uncertainty exists also because the maturation process can reverse this causality and itself affect growth and body condition. In addition, disentangling the contributions of polygenic and major loci can be important. In many fishes, males mature before females, enabling the study of associations between male maturation and maturation-unbiased female liability traits. Using 40 Atlantic salmon families, longitudinal common-garden experimentation, and quantitative genetic analyses, we disentangled environmental from polygenic and major locus (vgll3) effects on male maturation, and sex-specific growth and condition. We detected polygenic heritabilities for maturation, growth, and body condition, and vgll3 effects on maturation and body condition but not on growth. Longitudinal patterns for sex-specific phenotypic liability, and for genetic variances and correlations between sexes suggested that early growth and condition indeed positively affected maturation initiation. However, towards spawning time, causality appeared reversed for males whereby maturation affected growth negatively and condition positively via both the environmental and genetic effects. Altogether, the results indicate that growth and condition are useful traits to study liability for maturation initiation, but only until maturation alters their expression, and that vgll3 contributes to maturation initiation via condition.Peer reviewe

Revista de libros

Se reseñan los siguientes libros: - Diego F. Pro: Alberto Rouges. Editorial Valles Calchaquíes. Tucumán. 1957. Volumen rústica, 386 págs. -Jaroslaw M. Flys: El lenguaje poético de Federico García Lorca. Biblioteca Románica Hispánica. Madrid, Credos, 1955. Vol. rústica, 244 págs. - Sidney Hook: La educación del hombre moderno. Traducción directa del inglés por Josefina Ossorio Editorial Nova, colección “Biblioteca Nova de Educación”, Buenos Aires, 1957. Vol. rústica; 209 págs. - Charles Sherrington y otros: Las Bases Físicas de la Mente. Editorial Nueva Visión, Buenos Aires, 1957 (tr. y notas de A. L. Merani), 1 vol. en rústica de 103 págs. -L. Bethel, F. S. Atwater, G. II. E. Smith, H. A. Stackman. Jr: Dirección y Organización Industrial. Fondo de Cultura Económica México, 1955. Vol. rústica, 882 págs. -Rodolfo Mondolfo: Problemas de cultura y de educación. Editorial Hachette. Buenos Aires, 1957. Volumen rústica, 179 págs. - María de Villarino: Nuevas copla: de Martín Fierro. Editorial Kraft, Buenos Aires, 1957. Volumen rústica, 349 pág. -Homero: La Iliada. Traducción de Luis Segalá. Introducción e índices de Guillermo Thiele. Edición de Revista de Occidente, Madrid, para las ediciones de la Universidad de Puerto Rico. San Juan de Puerto Rico, 1956. Vol. rústica, CII + 602 págs.Universidad Nacional de La Plat

Enantioselective Phytotoxicity of the Herbicide Imazethapyr on the Response of the Antioxidant System and Starch Metabolism in Arabidopsis thaliana

Background: The enantiomers of a chiral compound possess different biological activities, and one of the enantiomers usually shows a higher level of toxicity. Therefore, the exploration of the causative mechanism of enantioselective toxicity is regarded as one of primary goals of biological chemistry. Imazethapyr (IM) is an acetolactate synthase (ALS)-inhibiting chiral herbicide that has been widely used in recent years with racemate. We investigated the enantioselectivity between R- and S-IM to form reactive oxygen species (ROS) and to regulate antioxidant gene transcription and enzyme activity. Results: Dramatic differences between the enantiomers were observed: the enantiomer of R-IM powerfully induced ROS formation, yet drastically reduced antioxidant gene transcription and enzyme activity, which led to an oxidative stress. The mechanism by which IM affects carbohydrate metabolism in chloroplasts has long remained a mystery. Here we report evidence that enantioselectivity also exists in starch metabolism. The enantiomer of R-IM resulted in the accumulation of glucose, maltose and sucrose in the cytoplasm or the chloroplast and disturbed carbohydrates utilization. Conclusion: The study suggests that R-IM more strongly retarded plant growth than S-IM not only by acting on ALS, but also by causing an imbalance in the antioxidant system and the disturbance of carbohydrate metabolism wit

Penetration of the Stigma and Style Elicits a Novel Transcriptome in Pollen Tubes, Pointing to Genes Critical for Growth in a Pistil

Pollen tubes extend through pistil tissues and are guided to ovules where they release sperm for fertilization. Although pollen tubes can germinate and elongate in a synthetic medium, their trajectory is random and their growth rates are slower compared to growth in pistil tissues. Furthermore, interaction with the pistil renders pollen tubes competent to respond to guidance cues secreted by specialized cells within the ovule. The molecular basis for this potentiation of the pollen tube by the pistil remains uncharacterized. Using microarray analysis in Arabidopsis, we show that pollen tubes that have grown through stigma and style tissues of a pistil have a distinct gene expression profile and express a substantially larger fraction of the Arabidopsis genome than pollen grains or pollen tubes grown in vitro. Genes involved in signal transduction, transcription, and pollen tube growth are overrepresented in the subset of the Arabidopsis genome that is enriched in pistil-interacted pollen tubes, suggesting the possibility of a regulatory network that orchestrates gene expression as pollen tubes migrate through the pistil. Reverse genetic analysis of genes induced during pollen tube growth identified seven that had not previously been implicated in pollen tube growth. Two genes are required for pollen tube navigation through the pistil, and five genes are required for optimal pollen tube elongation in vitro. Our studies form the foundation for functional genomic analysis of the interactions between the pollen tube and the pistil, which is an excellent system for elucidation of novel modes of cell–cell interaction