Les Annales coloniales : organe de la "France coloniale moderne" / directeur : Marcel Ruedel

1923/12/28 (A24,N176).

Les Annales coloniales : organe de la "France coloniale moderne" / directeur : Marcel Ruedel

1912/12/28 (A13,N143).

Les Annales coloniales : organe de la "France coloniale moderne" / directeur : Marcel Ruedel

1921/12/28 (A22,N157).

Co-evolutionary dynamics between public good producers and cheats in the bacterium Pseudomonas aeruginosa.

The production of beneficial public goods is common in the microbial world, and so is cheating - the exploitation of public goods by nonproducing mutants. Here, we examine co-evolutionary dynamics between cooperators and cheats and ask whether cooperators can evolve strategies to reduce the burden of exploitation, and whether cheats in turn can improve their exploitation abilities. We evolved cooperators of the bacterium Pseudomonas aeruginosa, producing the shareable iron-scavenging siderophore pyoverdine, together with cheats, defective in pyoverdine production but proficient in uptake. We found that cooperators managed to co-exist with cheats in 56% of all replicates over approximately 150 generations of experimental evolution. Growth and competition assays revealed that co-existence was fostered by a combination of general adaptions to the media and specific adaptions to the co-evolving opponent. Phenotypic screening and whole-genome resequencing of evolved clones confirmed this pattern, and suggest that cooperators became less exploitable by cheats because they significantly reduced their pyoverdine investment. Cheats, meanwhile, improved exploitation efficiency through mutations blocking the costly pyoverdine-signalling pathway. Moreover, cooperators and cheats evolved reduced motility, a pattern that likely represents adaptation to laboratory conditions, but at the same time also affects social interactions by reducing strain mixing and pyoverdine sharing. Overall, we observed parallel evolution, where co-existence of cooperators and cheats was enabled by a combination of adaptations to the abiotic and social environment and their interactions.

Stable eusociality via maternal manipulation when resistance is costless.

In many eusocial species, queens use pheromones to influence offspring to express worker phenotypes. Although evidence suggests that queen pheromones are honest signals of the queen's reproductive health, here I show that queen's honest signalling can result from ancestral maternal manipulation. I develop a mathematical model to study the coevolution of maternal manipulation, offspring resistance to manipulation and maternal resource allocation. I assume that (i) maternal manipulation causes offspring to be workers against offspring's interests; (ii) offspring can resist at no direct cost, as is thought to be the case with pheromonal manipulation; and (iii) the mother chooses how much resource to allocate to fertility and maternal care. In the coevolution of these traits, I find that maternal care decreases, thereby increasing the benefit that offspring obtain from help, which in the long run eliminates selection for resistance. Consequently, ancestral maternal manipulation yields stable eusociality despite costless resistance. Additionally, ancestral manipulation in the long run becomes honest signalling that induces offspring to help. These results indicate that both eusociality and its commonly associated queen honest signalling can be likely to originate from ancestral manipulation.

Neuvo-kirja : elli lyhykäinen oppi hyviin ja siivollisiin ihmisten tapoin; nuoruudelle

1. pain. nimityksellä "Lyhykäinen neuvo hyvihin ja sijvollisihin ihmisten tapoin" Turusa 1761

La Bastille : journal antimaçonnique / dir. Copin-Albancelli ; dir. Louis Dasté

1912/12/28 (A11,N466).

Les Belles images

1905/12/28 (N89).

Les Belles images

1933/12/28 (N1528).

Les Belles images

1911/12/28 (N402).

Constituintes químicos de Arrabidaea samydoides (Bignoniaceae)

Chemical investigation of Arrabidaea samydoides resulted in the isolation of the flavone chrysin; five triterpenes: lupeol, ursolic acid, 3b,16a-dihydroxy-urs-12-ene, uvaol, and erythrodiol; and two sterols: sitosterol and stigmasterol. The structures of these compounds were established by spectroscopic analysis. This paper deal with the first phytochemical study of Arrabidaea samydoides.

La Calotte

1906/12/28 (A1,N16).

Le Capitaliste : journal de la banque parisienne

1906/12/28 (A29,N52).

Le Capitaliste : journal de la banque parisienne

1881/12/28 (A4,N52).

Le Capitaliste : journal de la banque parisienne

1887/12/28 (A10,N52).