Interest of targeted genome modification techniques in terrestrial livestock species

Des nouvelles nucléases permettent de modifier le génome de nombreuses espèces de façon ciblée ; à un endroit précis et défini dudit génome. Concernant les animaux de rente, les applications envisagées peuvent se classer dans trois grandes perspectives: (i) les projets à visée de recherche fondamentale, lorsque l’espèce murine ne peut pas être utilisée (cornage, saisonnalité, à titre d’exemples) ; (ii) les projets à visée biomédicale pour créer des animaux modèles de pathologies humaines quand le modèle murin n’est pas adéquat ; et (iii) les projets à visée agronomique pour apporter un caractère favorable, décrit dans une autre espèce ou race, à une race ou une espèce ne possédant pas ce caractère. Ces techniques représentent une alternative très efficace à l’introgression, tout en abolissant la barrière d’espèce. Elles pourront également être envisagées en appui à la sélection génomique pour éliminer les allèles défavorables lorsque leur utilisation sera autorisée en Europe, ce qui n’est pas encore le cas.Nowadays, new endonucleases make it possible to target precisely defined alterations in the genomic DNA of many species. With regard to livestock, the envisaged applications can be divided into three broad perspectives: (i) the projects with a basic research objective, when the mouse species cannot be used (horns development, seasonality, as examples) ; (ii) biomedical projects to create animal models of human pathologies when the mouse model is not adequate ; and (iii) agronomic projects aimed at providing an interesting character already described in another species or race, into a race or species not possessing such a character. These techniques represent a very effective alternative to introgression, while abolishing the species barrier. They may also be considered in support of genomic selection to eliminate advers

Identification of transcripts involved in meiosis and follicle formation during ovine ovary development

<p>Abstract</p> <p>Background</p> <p>The key steps in germ cell survival during ovarian development are the entry into meiosis of oogonies and the formation of primordial follicles, which then determine the reproductive lifespan of the ovary. In sheep, these steps occur during fetal life, between 55 and 80 days of gestation, respectively. The aim of this study was to identify differentially expressed ovarian genes during prophase I meiosis and early folliculogenesis in sheep.</p> <p>Results</p> <p>In order to elucidate the molecular events associated with early ovarian differentiation, we generated two ovary stage-specific subtracted cDNA libraries using SSH. Large-scale sequencing of these SSH libraries identified 6,080 ESTs representing 2,535 contigs. Clustering and assembly of these ESTs resulted in a total of 2,101 unique sequences depicted in 1,305 singleton (62.11%) and 796 contigs (37.9%) ESTs (clusters). BLASTX evaluation indicated that 99% of the ESTs were homologous to various known genes/proteins in a broad range of organisms, especially ovine, bovine and human species. The remaining 1% which exhibited any homology to known gene sequences was considered as novel. Detailed study of the expression patterns of some of these genes using RT-PCR revealed new promising candidates for ovary differentiation genes in sheep.</p> <p>Conclusion</p> <p>We showed that the SSH approach was relevant to determining new mammalian genes which might be involved in oogenesis and early follicle development, and enabled the discovery of new potential oocyte and granulosa cell markers for future studies. These genes may have significant implications regarding our understanding of ovarian function in molecular terms, and for the development of innovative strategies to both promote and control fertility.</p

Positional cloning of the PIS mutation in goats and its impact on understanding mammalian sex-differentiation

In goats, the PIS (polled intersex syndrome) mutation is responsible for both the absence of horns in males and females and sex-reversal affecting exclusively XX individuals. The mode of inheritance is dominant for the polled trait and recessive for sex-reversal. In XX PIS-/- mutants, the expression of testis-specific genes is observed very precociously during gonad development. Nevertheless, a delay of 4–5 days is observed in comparison with normal testis differentiation in XY males. By positional cloning, we demonstrate that the PIS mutation is an 11.7-kb regulatory-deletion affecting the expression of two genes, PISRT1 and FOXL2 which could act synergistically to promote ovarian differentiation. The transcriptional extinction of these two genes leads, very early, to testis-formation in XX homozygous PIS-/- mutants. According to their expression profiles and bibliographic data, we propose that FOXL2 may be an ovary-differentiating gene, and the non-coding RNA PISRT1, an anti-testis factor repressing SOX9, a key regulator of testis differentiation. Under this hypothesis, SRY, the testis-determining factor would inhibit these two genes in the gonads of XY males, to ensure testis differentiation

A hermaphrodite dog with bilateral ovotestes and pyometra

Hermaphroditism was identified in a 3-year-old American Cocker spaniel with an enlarged os clitoridis that was shown as reddish finger-like structure protruding from the vulva. The urethral orifice was located cranially to the base of the os clitoridis. The gonads were situated caudal to the kidneys at the cranial tips of the uterine horns, and were composed mainly of seminiferous tubules and interstitial cells and had ovarian follicles in the cortices. The uterus was enlarged and revealed pyometra. Gross and histopathological findings of the dog suggested hermaphroditism with bilateral ovotestes and pyometra

R-spondin1 and FOXL2 act into two distinct cellular types during goat ovarian differentiation

<p>Abstract</p> <p>Background</p> <p>Up to now, two loci have been involved in XX sex-reversal in mammals following loss-of-function mutations, PIS (Polled Intersex Syndrome) in goats and <it>R-spondin1 </it>(<it>RSPO1</it>) in humans. Here, we analyze the possible interaction between these two factors during goat gonad development. Furthermore, since functional redundancy between different <it>R-spondins </it>may influence gonad development, we also studied the expression patterns of <it>RSPO2, 3 </it>and <it>4</it>.</p> <p>Results</p> <p>Similarly to the mouse, <it>RSPO1 </it>shows a sex-dimorphic expression pattern during goat gonad development with higher levels in the ovaries. Interestingly, the PIS mutation does not seem to influence its level of expression. Moreover, using an RSPO1 specific antibody, the RSPO1 protein was localized in the cortical area of early differentiating ovaries (36 and 40 d<it>pc</it>). This cortical area contains the majority of germ cell that are surrounded by FOXL2 negative somatic cells. At latter stages (50 and 60 d<it>pc</it>) RSPO1 protein remains specifically localized on the germ cell membranes. Interestingly, a time-specific relocation of RSPO1 on the germ cell membrane was noticed, moving from a uniform distribution at 40 d<it>pc </it>to a punctuated staining before and during meiosis (50 and 60 d<it>pc </it>respectively). Interestingly, also <it>RSPO2 </it>and <it>RSPO4 </it>show a sex-dimorphic expression pattern with higher levels in the ovaries. Although <it>RSPO4 </it>was found to be faintly and belatedly expressed, the expression of <it>RSPO2 </it>increases at the crucial 36 d<it>pc </it>stage, as does that of <it>FOXL2</it>. Importantly, <it>RSPO2 </it>expression appears dramatically decreased in XX PIS^-/-gonads at all three tested stages (36, 40 and 50 d<it>pc</it>).</p> <p>Conclusion</p> <p>During goat ovarian development, the pattern of expression of <it>RSPO1 </it>is in agreement with its possible anti-testis function but is not influenced by the PIS mutation. Moreover, our data suggest that RSPO1 may be associated with germ cell development and meiosis. Interestingly, another RSPO gene, RSPO2 shows a sex-dimorphic pattern of expression that is dramatically influenced by the PIS mutation.</p

Foxl2 gene and the development of the ovary : a story about goat, mouse, fish and woman

In this review, we describe recent results concerning the genetics of sex determination in mammals. Particularly, we developed the study of the FOXL2 gene and its implication in genetic anomalies in goats (PIS mutation) and humans (BPES). We present the expression of FOXL2 in the ovaries of different species

Novel Insights into the Bovine Polled Phenotype and Horn Ontogenesis in Bovidae

Despite massive research efforts, the molecular etiology of bovine polledness and the developmental pathways involved in horn ontogenesis are still poorly understood. In a recent article, we provided evidence for the existence of at least two different alleles at the Polled locus and identified candidate mutations for each of them. None of these mutations was located in known coding or regulatory regions, thus adding to the complexity of understanding the molecular basis of polledness. We confirm previous results here and exhaustively identify the causative mutation for the Celtic allele (PC) and four candidate mutations for the Friesian allele (PF). We describe a previously unreported eyelash-and-eyelid phenotype associated with regular polledness, and present unique histological and gene expression data on bovine horn bud differentiation in fetuses affected by three different horn defect syndromes, as well as in wild-type controls. We propose the ectopic expression of a lincRNA in PC/p horn buds as a probable cause of horn bud agenesis. In addition, we provide evidence for an involvement of OLIG2, FOXL2 and RXFP2 in horn bud differentiation, and draw a first link between bovine, ovine and caprine Polled loci. Our results represent a first and important step in understanding the genetic pathways and key process involved in horn bud differentiation in Bovidae

The forkhead transcription factor FOXL2 is expressed in somatic cells of the human ovary prior to follicle formation

Interactions between germ cells and surrounding somatic cells are central to ovarian development as well as later function. Disruption of these interactions arising from abnormalities in either cell type can lead to premature ovarian failure (POF). The forkhead transcription factor FOXL2 is a candidate POF factor, and mutations in the FOXL2 gene are associated with syndromic and non-syndromic ovarian failure. Foxl2-deficient mice display major defects in primordial follicle activation with consequent follicle loss, and earlier roles in gonadal development and sex determination have also been suggested. However, despite its importance no data presently exist on its expression in the developing human ovary. Expression of FOXL2 mRNA was demonstrated in the human fetal ovary between 8 and 19 weeks gestation, thus from soon after sex determination to primordial follicle development. Expression in the ovary was higher after 14 weeks than at earlier gestation weeks and was very low in the fetal testis at all ages examined. Immunolocalization revealed FOXL2 expression to be confined to somatic cells, both adjacent to germ cells and those located in the developing ovarian stroma. These cells are the site of action of oocyte-derived activin signalling, but in vitro treatment of human fetal ovaries with activin failed to reveal any regulation of FOXL2 transcription by this pathway. In summary, the expression of FOXL2 in somatic cells of the developing human ovary before and during follicle formation supports a conserved and continuing role for this factor in somatic/germ cell interactions from the earliest stages of human ovarian development

Биофизика зрительной сенсорной системы человека

Зрительная сенсорная система – это система, которая воспринимает излучение видимого спектра, после чего формируется изображение предметов окружающей среды в виде определенных ощущений (сенсорных чувств)

Bovine Polledness – An Autosomal Dominant Trait with Allelic Heterogeneity

The persistent horns are an important trait of speciation for the family Bovidae with complex morphogenesis taking place briefly after birth. The polledness is highly favourable in modern cattle breeding systems but serious animal welfare issues urge for a solution in the production of hornless cattle other than dehorning. Although the dominant inhibition of horn morphogenesis was discovered more than 70 years ago, and the causative mutation was mapped almost 20 years ago, its molecular nature remained unknown. Here, we report allelic heterogeneity of the POLLED locus. First, we mapped the POLLED locus to a ∼381-kb interval in a multi-breed case-control design. Targeted re-sequencing of an enlarged candidate interval (547 kb) in 16 sires with known POLLED genotype did not detect a common allele associated with polled status. In eight sires of Alpine and Scottish origin (four polled versus four horned), we identified a single candidate mutation, a complex 202 bp insertion-deletion event that showed perfect association to the polled phenotype in various European cattle breeds, except Holstein-Friesian. The analysis of the same candidate interval in eight Holsteins identified five candidate variants which segregate as a 260 kb haplotype also perfectly associated with the POLLED gene without recombination or interference with the 202 bp insertion-deletion. We further identified bulls which are progeny tested as homozygous polled but bearing both, 202 bp insertion-deletion and Friesian haplotype. The distribution of genotypes of the two putative POLLED alleles in large semi-random sample (1,261 animals) supports the hypothesis of two independent mutations