Christian Aimar

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In vertebrates, only few experiments have been performed in microgravity to study the embryonic development from fertilization. To date, these concern only amphibian and fish. We report here a study on the embryonic development of Pleurodeles waltl (urodele amphibian) eggs oviposited in microgravity. The experiment was performed twice on board the Mir space(More)
Pleurodeles waltl (amphibian, Urodele) is an appropriate biological model for space experiments on a vertebrate. One reason for interest in this animal concerns the study of the effects of absence of gravity on embryonic development. First, after mating (on Earth) the females retain live, functional sperm in their cloacum for up to 5 months, allowing normal(More)
The entire 1731 retrotransposon of Drosophila melanogaster, tagged with the E. coli lac Z gene inserted in its gag sequence, was injected into oocytes and fertilized eggs of the urodele amphibian Pleurodeles waltl. Expression of the reporter gene indicated that the 1731 promoter (its 5'LTR) is active in the embryos and not in the oocytes. It appeared that(More)
The activity of prolactin (PRL) cells was investigated in goldfish gradually adapted to diluted (30%) artificial seawater (ASW) or directly immersed in 23% ASW and in similar saline solutions free of calcium. When Ca2+ is omitted, PRL cells appear slightly more active than those in saline solutions with calcium, nuclear areas having intermediate values(More)
Goldfish kept in diluted Ca-free sea water (SW) (23 or 30%) or in Ca-Mg-deficient SW (23%) have a limited survival, release large amounts of mucus, and show spasmodic seizures. Plasma calcium decreases. The PAS-positive calcium-sensitive (Ca-s) cells of the pars intermedia show a low activity in diluted SW and in 23% Mg-free SW. In diluted Ca-free SW, Ca-s(More)
In the goldfish, one cell type of the pars intermedia, slightly PAS positive, is highly stimulated in deionized water (E Dés). This response is not influenced by the pH of the water (E Dés pH 5.3, E Dés buffered with imidazole pH 6.7) for 20 days. Stimulation is prevented when the E Dés is supplemented with CaCl2 (2mM), but it is not affected by the(More)
Cytological changes in the calcium-sensitive (Ca-s) cells (formerly termed PAS-positive cells) of the pars intermedia were investigated in the goldfish after adaptation to deionized water (DW), with or without addition of sodium, potassium and magnesium. These ions were added as chloride salts at concentrations similar to those present in fresh water (FW).(More)
In Pleurodeles waltlii (Urodela) larvae, spontaneous activity and the tendency to leave water are significantly influenced by artificial air ionization. Atmospheric ions of negative and positive polarities have opposite effects: the latter reduce spontaneous activity by 48% whereas negative ions increase it by 39%. This difference must be considered the(More)
In the pituitary of an Amphibian (Urodela), various cell types were localized by cytoimmunological techniques: corticotrophs located in a rostral zone near the median eminence, ventral orangeophilic cells secreting a prolactin-like hormone and erythrosinophilic cells in a more dorso-caudal situation secreting growth hormone. Alpha-MSH and beta-MSH produceng(More)
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