Spatial Factors for Triplet Fusion Reaction of Singlet Oxygen Photosensitization

International audienceFirst-principles quantum-chemical description of photosensitized singlet oxygen generation kinetics is challenging due to the intrinsic complexity of the underlying triplet fusion process in a floppy molecular complex with open-shell character. With a quantum-chemical kinetic model specifically tailored to deal with this problem, the reaction rates are investigated as a function of intermolecular incidence direction, orientation, and distance between O2 and the photosensitizer. The adopted photosensitizer, 6-azo-2-thio-thymine, combines practical interest and prototypical variability. The study quantitatively determined maximum singlet oxygen generation rates for fifteen incidence/orientation directions, showing that they span five orders of magnitude between the largest and the smallest rate. Such information may provide a hands-on guideline for the experimental molecular design of new photosensitizers as well as further higher-level theoretical research. TOC grap

Breeding, planktonic and settlement factors shape recruitment patterns of one of the last remaining major population of Pinna nobilis within Spanish waters

The pen shell, Pinna nobilis L., is a critically endangered bivalve threatened by mass mortality events throughout the Mediterranean, but the Alfacs Bay (Ebro Delta) still hosts many healthy individuals. Herein, we study the main factors controlling recruitment patterns in this locality, including gonadal development and abundance of critical life-stages, as well as the effect of environmental factors. Growth records from empty shells suggested a single major peak of recruitment during a period of 11 years, although many juveniles were found in two very shallow sand bars possibly acting as a barrier for water circulation and as a trap for larvae. Collectors deployed outside these sand bar areas showed zero settlers, and the availability of planktonic larvae was very low. Gonadal examination evidenced breeding throughout the summer period with successive hermaphroditism, but 20% of individuals were simultaneous hermaphrodites, a condition that has been associated with environmental stress and that could lead to in-breeding depression and potentially reduced fertility. Yet, given the large size of the population and the wide breeding period observed, planktonic processes causing larval mortality such as freshwater discharges from rice locally important rice agriculture are also proposed as possible impacts accounting for patterns of low larval availability.info:eu-repo/semantics/acceptedVersio

Identification of potential recruitment bottlenecks in larval stages of the giant fan mussel Pinna nobilis using specific quantitative PCR

Pinna nobilis is an endangered species of fan mussel found along coastal Mediterranean waters requiring special attention for conservation. Populations are restricted in number, due to anthropogenic disturbances, disease, and in some areas, low rates of recruitment. To date, the difficulties associated with the identification of planktonic stages have prompted the use of benthic collectors as a proxy for quantifying larval supply, despite important information being lost regarding planktonic processes. We present evidence of spawning utilizing a qPCR assay developed for detecting genomic DNA of P. nobilis to enable specific identification of planktonic stages to augment knowledge of P. nobilis life history. In the Ebro Delta, Spain, it has been used to study what might be limiting their reproduction locally. We demonstrate the ability to differentiate DNA of P. nobilis from other bivalve mollusks and distinguish between fertilized and unfertilized eggs of P. nobilis, which may be a crucial point for understanding the low level of recruitment seen in this natural population. We also show evidence of larval presence during the expected spawning period, although abundance in positive samples were so low that they pose new questions about factors controlling the availability of planktonic stages of P. nobilis.info:eu-repo/semantics/acceptedVersio

Adult spawning and early larval development of the endangered bivalve Pinna nobilis

[EN] The development of aquaculture activities has posed an alternative solution for the preservation of some overexploited shell¿sh ¿sheries worldwide. In the same way, endemic Mediterranean bivalves such as Pinna nobilis, highly threatened by habitat loss and coastal pollution, could found in aquaculture a solution for preserving the continuity of the species. Given the endangered status of the species, the biological and ecological processes regulating natural populations have been well studied, but there are still important knowledge gaps preventing the development of viable arti¿cial cultures. This study describes for the ¿rst time the larval development of P. nobilis (from fertilization until pediveliger larval stages) in captivity conditions. Moreover, di¿erent rearing tanks of 5, 16 and 80 L, larvae density from 1 to 600 larvae mL¿1, light conditions, food doses, were tested in order to establish the bases for the optimal rearing of the species and provide a source of individuals for restoring ¿eld populations. Results showed that 16 L tanks with a concentration of 2 larvae mL¿1, constant temperature of 21 °C, 12/12 h photoperiod and fed with an ¿optimal¿ mixture of 25 cells per ¿L of Chaetoceros calcitrans + 33.3 cells per¿L ofPavlova lutheri + 100 cells per¿L ofIsochrysis galbana¿ appear to be the best conditions to rearlarvae ofP. nobilis.Di¿erentcaptivity conditions such as loweror highertank volume, larvae density, or food doses; light privation did not report better results for larval development.The present study was financed by the Caisse d'Epargne Cote d'Azur. We are also grateful to the research crew of the Institut Oceanographique Paul Ricard and the Catholic University of Valencia for their technical support and help collecting and maintaining fan mussels. Special thanks to the reviewers for their constructive and necessary suggestions.Trigos, S.; Vicente, N.; Prado, P.; Espinos Gutierrez, FJ. (2018). Adult spawning and early larval development of the endangered bivalve Pinna nobilis. Aquaculture. 483:102-110. doi:10.1016/j.aquaculture.2017.10.015S10211048

Occurrence of Association of <i>Pinna nobilis</i> with Two Decapod Species in Mediterranean French Waters

International audienc

Transplantation protocol for the fan mussel Pinna nobilis in different types of substrate

International audienc

Population status of pinna nobilis in four protected areas of France and Monaco

International audienc

Uncountable products of determined groups need not be determined

If H is a dense subgroup of G, we say that H determines G if their groups of characters are topologically isomorphic when equipped with the compact open topology. If every dense subgroup of G determines G, then we say that G is determined. The importance of this property is justified by the recent generalizations of Pontryagin-van Kampen duality to wider classes of topological Abelian groups. Among other results, we show (a) ⊕i ∈ I R determines the product ∏i ∈ I R if and only if I is countable, (b) a compact group is determined if and only if its weight is countable. These answer questions of Comfort, Raczkowski and the third listed author. Generalizations of the above results are also given. © 2008 Elsevier Inc

Identification of potential recruitment bottlenecks in larval stages of the giant fan mussel <i>Pinna nobilis</i> using specific quantitative PCR

International audiencePinna nobilis is an endangered species of fan mussel found along coastal Mediterranean waters requiring special attention for conservation. Populations are restricted in number, due to anthropogenic disturbances, disease, and in some areas, low rates of recruitment. To date, the difficulties associated with the identification of planktonic stages have prompted the use of benthic collectors as a proxy for quantifying larval supply, despite important information being lost regarding planktonic processes. We present evidence of spawning utilizing a qPCR assay developed for detecting genomic DNA of P. nobilis to enable specific identification of planktonic stages to augment knowledge of P. nobilis life history. In the Ebro Delta, Spain, it has been used to study what might be limiting their reproduction locally. We demonstrate the ability to differentiate DNA of P. nobilis from other bivalve mollusks and distinguish between fertilized and unfer-tilized eggs of P. nobilis, which may be a crucial point for understanding the low level of recruitment seen in this natural population. We also show evidence of larval presence during the expected spawning period, although abundance in positive samples were so low that they pose new questions about factors controlling the availability of planktonic stages of P. nobilis