%0 Newspaper Article %B Aquatic Invasions %D 2020 %T Establishment and population features of the non-native Atlantic rangia, Rangia cuneata (Mollusca: Bivalvia), in northwestern France %A Robin Faillettaz %A Christophe Roger %A Michel Mathieu %A Jean-Paul Robin %A Katherine Costil %K Alien species %K brackish waters %K density %K Growth %K Normandy (F) %K Reproduction %K The Atlantic rangia %X The presence of shells of the Atlantic rangia, Rangia cuneata, a brackish-water species native from the Gulf of Mexico also known as gulf wedge clam, was reported in 2017 on the French coasts of the English Channel, in the waterway that connects Caen to the sea. However, no information was available on whether a population of this alien species had successfully established in the region. Here, only empty shells—except for one live individual—were sampled in that waterway, and the sampling was shifted to the nearby marina of Ouistreham, where water is mesohaline (6.89 ± SD 0.06 PSU). In spring 2017, the mean density in the marina reached 110.45 ± 86.08 ind m-2, largely dominating the benthos community. The population was mostly composed of fairly large individuals, with no young-of-the-year found inside the marina. The modal values of the size frequency distribution ranged between 35 and 40 mm shell length. The growth patterns determined from the annual rings suggest a maximum lifespan of eight completed years. Following the assumption that colonization occurred at the larval stage, as in other European countries, this population may have established in 2009, i.e. only four years after its first detection in Europe, in the Antwerp harbour. The specimens collected are the largest recorded in European waters, suggesting that a highly suitable environment for the species in the region. Given the invasive potential of Atlantic rangia within the last decade, a close monitoring of this population and of the spread of the species in French and European waters appears necessary to determine its impacts on these ecosystems. %B Aquatic Invasions %V 15 %P 367-381 %G eng %0 Journal Article %J Gen Comp Endocrinol %D 2014 %T Neuroendocrine gene expression reveals a decrease in dopamine D2B receptor with no changes in GnRH system during prepubertal metamorphosis of silvering in wild Japanese eel. %A Jeng, Shan-Ru %A Wen-Shiun Yueh %A Pen, Yi-Ting %A Lee, Yan-Horn %A Chen, Guan-Ru %A Sylvie Dufour %A Chang, Ching-Fong %K Animals %K Cells, Cultured %K Dopamine %K Eels %K Female %K Follicle Stimulating Hormone, beta Subunit %K Gene Expression Regulation %K Gonadotropin-Releasing Hormone %K Immunoblotting %K Immunoenzyme Techniques %K Luteinizing Hormone, beta Subunit %K Metamorphosis, Biological %K Neurosecretory Systems %K Oocytes %K Ovary %K Real-Time Polymerase Chain Reaction %K Receptors, Dopamine D2 %K Reproduction %K Reverse Transcriptase Polymerase Chain Reaction %K RNA, Messenger %K Sexual Maturation %K Skin Pigmentation %X

Silvering is a prepubertal metamorphosis preparing the eel to the oceanic reproductive migration. A moderate gonad development occurs during this metamorphosis from the sedentary yellow stage to the migratory silver stage. The aim of this study was to elucidate the molecular aspects of various endocrine parameters of BPG axis at different ovarian developmental stages in wild yellow and silver female Japanese eels. The GSI of the sampled female eels ranged between 0.18 and 2.3%, corresponding to yellow, pre-silver and silver stages. Gonad histology showed changes from previtellogenic oocytes in yellow eels to early vitellogenic oocytes in silver eels. Both serum E2 and T concentrations significantly increased with ovarian development indicating a significant activation of steroidogenesis during silvering. In agreement with previous studies, significant increases in pituitary gonadotropin beta subunits FSH-β and LH-β transcripts were also measured by qPCR, supporting that the activation of pituitary gonadotropin expression is likely responsible for the significant ovarian development observed during silvering. We investigated for the first time the possible brain neuroendocrine mechanisms involved in the activation of the pituitary gonadotropic function during silvering. By analyzing the expression of genes representative of the stimulatory GnRH control and the inhibitory dopaminergic control. The transcript levels of mGnRH and the three GnRH receptors did not change in the brain and pituitary between yellow and silver stages, suggesting that gene expression of the GnRH system is not significantly activated during silvering. The brain transcript levels of tyrosine hydroxylase, limiting enzyme of DA synthesis did not change during silvering, indicating that the DA synthesis activity was maintained. In contrast, a significant decrease in DA-D2B receptor expression in the forebrain and pituitary was observed, with no changes in DA-D2A receptor. The decrease in the pituitary expression of DA-D2BR during silvering would allow a reduced inhibitory effect of DA. We may raise the hypothesis that this regulation of D2BR gene expression is one of the neuroendocrine mechanisms involved in the slight activation of the pituitary gonadotropin and gonadal activity that occur at silvering.

%B Gen Comp Endocrinol %V 206 %P 8-15 %8 2014 Sep 15 %G eng %R 10.1016/j.ygcen.2014.08.001