Manipulations génétiques et cellulaires de la spermatogenèse chez la souris

Des constructions d'ADN, en présence d'agent transfectant, ont été injectées dans les tubes séminifères de souris adultes, en vue de générer des animaux transgéniques. Il a été mis en évidence une transmission mosaïque et épisomale du plasmide après croisement de mâles micro-injectés avec des femelles sauvages.Suite à ces expériences, nous avons développé deux approches distinctes. La première consiste à incuber des spermatozoïdes in vitro avec un anticorps " anti-spermatozoïde " couplé à un transgène avant de réaliser une fécondation in vitro. Bien qu'un marquage de l'acrosome du spermatozoïde de souris ait été observé sur frottis pour deux anticorps, aucun marquage n'a pu être retrouvé en présence du milieu de fécondation in vitro utilisé Dans un deuxième temps, nous avons mis au point la technique de transplantations croisées de cellules germinales, par injection via le rete testis, afin d'étudier les causes d'une dégénérescence de cellules germinales chez un modèle animal murin.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Glutathion S-Transferase genetic polymorphisms modify the effect of exposure to solvents during pregnancy on risk of birth defects

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Tex 19 paralogs exhibit a gonad and placenta-specific expression in the mouse.

International audienceWe have previously suggested that TEX19, a mammalian-specific protein of which two paralogs exist in rodents, could be implicated in stem cell self-renewal and pluripotency. We have established here the expression profiles of Tex19.1 and Tex19.2 during mouse development and adulthood. We show that both genes are coexpressed in the ectoderm and then in primordial germ cells (PGCs). They are also coexpressed in the testis from embryonic day 13.5 to adulthood, whereas only Tex19.1 transcripts are detected in the developing and adult ovary as well as in the placenta and its precursor tissue, the ectoplacental cone. The presence of both Tex19.1 and Tex19.2 in PGCs, gonocytes and spermatocytes opens the possibility that these two genes could play redundant functions in male germ cells. Furthermore, the placental expression of Tex19.1 can explain why Tex19.1 knockout mice show embryonic lethality, in addition to testis defects

Spermatogonia Differentiation Requires Retinoic Acid Receptor γ

International audienceVitamin A is instrumental to mammalian reproduction. Its metabolite, retinoic acid (RA), acts in a hormone-like manner through binding to and activating three nuclear receptor isotypes, RA receptor (RAR)α (RARA), RARβ, and RARγ (RARG). Here, we show that 1) RARG is expressed by A aligned (Aal) spermatogonia, as well as during the transition from Aal to A1 spermatogonia, which is known to require RA; and 2) ablation of Rarg, either in the whole mouse or specifically in spermatogonia, does not affect meiosis and spermiogenesis but impairs the Aal to A1 transition in the course of some of the seminiferous epithelium cycles. Upon ageing, this phenomenon yields seminiferous tubules containing only spermatogonia and Sertoli cells. Altogether, our findings indicate that RARG cell-autonomously transduces, in undifferentiated spermatogonia of adult testes, a RA signal critical for spermatogenesis. During the prepubertal spermatogenic wave, the loss of RARG function can however be compensated by RARA, as indicated by the normal timing of appearance of meiotic cells in Rarg-null testes. Accordingly, RARG- and RARA-selective agonists are both able to stimulate Stra8 expression in wild-type prepubertal testes. Interestingly, inactivation of Rarg does not impair expression of the spermatogonia differentiation markers Kit and Stra8, contrary to vitamin A deficiency. This latter observation supports the notion that the RA-signaling pathway previously shown to operate in Sertoli cells also participates in spermatogonia differentiation

Reproduction Function in Male Patients With Bardet Biedl Syndrome

International audiencePurpose: Bardet-Biedl syndrome (BBS) is a ciliopathy with a wide spectrum of symptoms due to primary cilia dysfunction, including genitourinary developmental anomalies as well as impaired reproduction, particularly in males. Primary cilia are known to be required at the following steps of reproduction function: (i) genitourinary organogenesis, (ii) in fetal firing of hypothalamo-pituitary axe, (iii) sperm flagellum structure, and (iv) first zygotic mitosis conducted by proximal sperm centriole. BBS phenotype is not fully understood.Methods: This study explored all steps of reproduction in 11 French male patients with identified BBS mutations.Results: BBS patients frequently presented with genitourinary malformations, such as cryptorchidism (5/11), short scrotum (5/8), and micropenis (5/8), but unexpectedly, with normal testis size (7/8). Ultrasonography highlighted epididymal cysts or agenesis of one seminal vesicle in some cases. Sexual hormones levels were normal in all patients except one. Sperm numeration was normal in 8 out of the 10 obtained samples. Five to 45% of sperm presented a progressive motility. Electron microscopy analysis of spermatozoa did not reveal any homogeneous abnormality. Moreover, a psychological approach pointed to a decreased self-confidence linked to blindness and obesity explaining why so few BBS patients express a child wish.Conclusions: Primary cilia dysfunction in BBS impacts the embryology of the male genital tract, especially epididymis, penis, and scrotum through an insufficient fetal androgen production. However, in adults, sperm structure does not seem to be impacted. These results should be confirmed in a greater BBS patient cohort, focusing on fertility

The mammalian-specific Tex19.1 gene plays an essential role in spermatogenesis and placenta-supported development

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