Altered gravity affects ventral root activity during fictive swimming and the static vestibuloocular reflex in young tadpoles (Xenopus laevis).

During early periods of life, modifications of the gravitational environment affect the development of sensory, neuronal and motor systems. The vestibular system exerts significant effects on motor networks that control eye and body posture as well as swimming. The objective of the present study was to study whether altered gravity (AG) affects vestibuloocular and spinal motor systems in a correlated manner.

Morphometric investigations of sensory vestibular structures in tadpoles (Xenopus laevis) after a spaceflight: implications for microgravity-induced alterations of the vestibuloocular reflex.

In lower vertebrates, gravity deprivation by orbital flights modifies the vestibuloocular reflex. Using the amphibian Xenopus laevis, the experiments should clarify to which extent macular structures of the labyrinth are responsible for these modifications. In particular, the shape of otoconia and number and size of sensory macular cells expressing CalBindin were considered.

The immunostimulatory peptide WKYMVm-NH activates bone marrow mouse neutrophils via multiple signal transduction pathways.

G-protein-coupled receptors play a major role in the activation of the innate immune system, such as polymorphonuclear neutrophils. Members of the formyl peptide receptor family recognize chemotactic peptides as well the amyloïd-beta peptide and fragments of the human immunodeficiency virus envelope and may thus be implicated in major pathologies. The peptide WKYMVm-NH2 probably activates the receptor FPRL1 and its mouse orthologues Fpr-rs1 and Fpr-rs2.

Effects of a long-term spaceflight on immunoglobulin heavy chains of the urodele amphibian Pleurodeles waltl.

A variety of immune parameters are modified during and after a spaceflight. The effects of spaceflights on cellular immunity are well documented; however, little is known about the effects of these flights on humoral immunity. During the Genesis space experiment, two adult Pleurodeles waltl (urodele amphibian) stayed 5 mo onboard Mir and were subjected to oral immunization.

An European pupil project linked to the scientific aims of the experiment AQUARIUS-XENOPUS on the taxi Soyuz flight Andromede to ISS.

The German-French biological experiment AQUARIUS-XENOPUS which flew on the Soyuz flight Andromede to the International Space Station ISS (launched October 21, 2001 in Baikonour/Kazakhstan) was extended by an outreach project. Pupils of class 10 to 12 from Ulm/D and Nancy-Tomblaine/F studied swimming behavior of Xenopus tadpoles on ground. They were instructed to perform all experimental steps following the protocol of similar video recordings on ISS.

Mouse bone marrow contains large numbers of functionally competent neutrophils.

The mouse has become an important model for immunological studies including innate immunity. Creating transgenic mice offers unique possibilities to study gene-function relationships. However, relatively little is known about the physiology of neutrophils from wild-type mice.

Developmental biology of urodele amphibians in microgravity conditions.

Among the urodele amphibians, only Cynops pyrrhogaster and Pleurodeles waltl, two species of the Salamandridae family, were used in space experiments. The advantages for using urodeles reside (i) in reproduction: a few months after natural breeding, females can lay eggs in absence of males after a hormonal treatment, because spermatozoa were preserved in the cloacal pelvic glands of matted females, (ii) in the rate of development which is slower in Cynops and Pleurodeles than in the anuran Xenopus, (iii) in their physiological properties: they can live in a closed water container or in a moisturized environment, and they can fast during several days. Moreover, urodeles have an important phylogenetic interest.

Differential expression of P450 aromatase during gonadal sex differentiation and sex reversal of the newt Pleurodeles waltl.

A better understanding of vertebrate sexual differentiation could be provided by a study of models in which genetic sex determination (GSD) of gonads can be reversed by temperature. In the newt Pleurodeles waltl, a P450 aromatase cDNA was isolated from adult gonads, and the nucleotide or deduced amino acid sequences showed a high level of identity with various vertebrate species. In adults, aromatase expression was found in gonads and brain.

Effects of space environment on embryonic growth up to hatching of salamander eggs fertilized and developed during orbital flights.

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.

An alternative internal splicing site defines new Ikaros isoforms in Pleurodeles waltl.

The Ikaros gene encodes a family of transcription factors which plays a crucial role in hematopoiesis. To improve our knowledge about the immune system of Pleurodeles waltl, we sequenced the cDNA coding for the Ik-1 isoform of that salamander and analyzed its tissue expression by semi-quantitative RT-PCR. Ikaros transcripts are abundant in the thymus and the spleen, thereby confirming that these organs are, respectively, the primary and secondary lymphoid tissues of Pleurodeles.

Sequencing and expression of the CD3 gamma/delta mRNA in Pleurodeles waltl (urodele amphibian).

The CD3 complex is an essential component of the T-cell receptor (TCR) implicated in T-cell maturation and activation. This TCR has been identified in both cartilaginous and bony vertebrates. In different studies where the CD3 chains were cloned and sequenced, it appeared that the CD3 complex is composed of several chains, all susceptible to phosphorylation and able to transduce signals.

Pleurodeles waltl, amphibian, Urodele, is a suitable biological model for embryological and physiological space experiments on a vertebrate.

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 in vivo fertilisation after hormonal stimulation.

Sex-linked differences in activity of enzymes in the blood of the urodele amphibian Pleurodeles waltl.

Few data are available on enzyme activity in amphibian plasma or erythrocytes. We measured the activity of several blood enzymes in the urodele amphibian Pleurodeles waltl reared under standard laboratory conditions. In subsequent experiments, we will estimate and compare the physiological and biochemical conditions of P.

Design of specific hardware to obtain embryos and maintain adult urodele amphibians aboard a space station.

The study of the influence of weightlessness on fertilization and embryonic development of a vertebrate is of importance in the understanding of basic embryogenesis and in the preparation of the future exploration of space. Accordingly, specific hardware was designed to perform experiments on board the MIR space station with an amphibian vertebrate model, taking into account the biological requirements and the multiple constraints of a long-term mission. This paper describes the biological uses and presents the technological specifications of the device developed under CNES management.

Effects of microgravity on the larval development, metamorphosis and reproduction of the urodele amphibian Pleurodeles waltl.

The FERTILE experiment was twice performed onboard the Mir space station during the Cassiopée and Pégase French space missions. The goal was to analyze the effects of microgravity on fertilization and embryonic development, and then on further development on the ground in the amphibian Pleurodeles waltl. The present paper reports development that occurred in the laboratory after landing.

The recombination-activating gene 1 of Pleurodeles waltl (urodele amphibian) is transcribed in lymphoid tissues and in the central nervous system.

The recombination-activating gene 1 (RAG1) product is required for the somatic rearrangement of immunoglobulin and T-cell receptor genes. We cloned and sequenced the large continuous open reading frame coding for the salamander Pleurodeles waltl RAG1 protein. Semi-quantitative RT-PCR experiments were performed to quantify the expression of RAG1 in different tissues.

Sex reversal of germ cell gametogenesis in chimeras of Pleurodeles waltl (urodele amphibian): genetic and immunogenetic demonstration using tolerance or rejection of skin grafts.

Viable chimeras were constituted with two cranial and caudal complementary pieces of embryos derived from two distinct histocompatible AA and BB strains, which were incompatible with each other. The embryonic gonads of the resulting chimeras constituted two homo- or heterosexual territories. In most heterosexual chimeras, the testicular territory sex reversed the ovarian territory.

Microgravity and hypergravity effects on fertilization of the salamander Pleurodeles waltl (urodele amphibian).

Effects of microgravity (microG) on fertilization were studied in the urodele amphibian Pleurodeles waltl on board the MIR space station. Genetic and cytomorphologic analyses ruled out parthenogenesis or gynogenesis and proved that fertilization did occur in microG. Actual fertilization was demonstrated by the analysis of the distribution of peptidase-1 genes, a polymorphic sex-linked enzyme, in progenies obtained in microG.

Appearance and evolution of calcitic and aragonitic otoconia during Pleurodeles waltl development.

The aim of this study is to determine the stages of appearance, morphology, crystallographic structure and chemical composition of otoconia during the inner ear development of an urodele amphibian, Pleurodeles waltl. The first otoconia are detected in the otocyst. Near hatching, calcitic otoconia are polyhedral in the saccule and cylindrical in the utricle.

High amounts of genetic differentiation between populations of the malaria vector Anopheles arabiensis from West Africa and eastern outer islands.

Polymorphism at nine microsatellite loci was examined to assess the level of genetic differentiation between four Anopheles arabiensis populations from Senegal, the high plateau of Madagascar, and Reunion and Mauritius islands. Eight of nine loci showed great polymorphism (2-16 alleles/locus) and significant genetic differentiation was revealed between all four populations by F- and R-statistics, with Fst estimates ranging from 0.080 to 0.

Crystallographic and chemical composition of otoconia in the salamander Pleurodeles waltl.

The aim of the present study was to define the morphology and the crystallographic and chemical composition of otoconia in different regions of the inner ear in Pleurodeles waltl (urodele amphibian). The inner ear of adults was microdissected and otoconia were analyzed by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray (EDX) and transmission electron microscopy. Two types of crystals were detected by SEM.

Sex reversal by aromatase inhibitor treatment in the newt Pleurodeles waltl.

Pleurodeles waltl is a newt with a ZZ male-ZW female sex determination mechanism, and a temperature-sensitive gonadal sex differentiation. Raising larvae at 32 degrees C from stage 42 to stage 54 (thermosensitive period) drives genetic females to differentiate into functional males. Estrogens are intimately linked with temperature action in this species, as well as in other vertebrates with temperature-dependent sex determination.

Expression of hindlimb abnormalities under rearing temperature effects during the larval development of the salamander Pleurodeles waltl (urodele amphibian).

Anomalie m.p. is a spontaneous and heritable hindlimb abnormality described earlier.

Grafts of ovaries in males and females of Pleurodeles waltl (urodele amphibia): evidence of a long-term tolerance of allografts; application following a space biology experiment.

Ovary grafts were investigated in the salamander Pleurodeles using juveniles and adults as donors and hosts. Ovaries were provided by standard or histo-compatible strains and by standard females which had been submitted to a space flight. Laparotomy of the hosts was used to control viability of grafts.

Purification and partial characterization of peptidase-1, a sex-linked enzyme in Pleurodeles waltl (urodele amphibian).

Peptidase-1 is a sex-linked enzyme, which can be purified from the liver of the amphibian urodele Pleurodeles waltl. We estimated its apparent molecular mass as 170 kDa by gel filtration chromatography. The enzyme is composed of two subunits with apparent molecular masses of 90 and 99 kDa.