Background: Embryonic development proceeds through finely tuned reprogramming of the parental genomes to form a totipotent embryo. Cells within this embryo will then differentiate and give rise to ...all the tissues of a new individual. Early embryonic development thus offers a particularly interesting system in which to analyze functional nuclear organization. When the organization of higher-order chromatin structures, such as pericentromeric heterochromatin, was first analyzed in mouse embryos, specific nuclear rearrangements were observed that correlated with embryonic genome activation at the 2-cell stage. However, most existing analyses have been conducted by visual observation of fluorescent images, in two dimensions or on z-stack sections/projections, but only rarely in three dimensions (3D). Results: In the present study, we used DNA fluorescent in situ hybridization (FISH) to localize centromeric (minor satellites), pericentromeric (major satellites), and telomeric genomic sequences throughout the preimplantation period in naturally fertilized mouse embryos (from the 1-cell to blastocyst stage). Their distribution was then analyzed in 3D on confocal image stacks, focusing on the nucleolar precursor bodies and nucleoli known to evolve rapidly throughout the first developmental stages. We used computational imaging to quantify various nuclear parameters in the 3D-FISH images, to analyze the organization of compartments of interest, and to measure physical distances between these compartments. Conclusions: The results highlight differences in nuclear organization between the two parental inherited genomes at the 1-cell stage, i.e. just after fertilization. We also found that the reprogramming of the embryonic genome, which starts at the 2-cell stage, undergoes other remarkable changes during preimplantation development, particularly at the 4-cell stage.
Background: Embryonic development proceeds through finely tuned reprogramming of the parental genomes to form a totipotent embryo. Cells within this embryo will then differentiate and give rise to ...all the tissues of a new individual. Early embryonic development thus offers a particularly interesting system in which to analyze functional nuclear organization. When the organization of higher-order chromatin structures, such as pericentromeric heterochromatin, was first analyzed in mouse embryos, specific nuclear rearrangements were observed that correlated with embryonic genome activation at the 2-cell stage. However, most existing analyses have been conducted by visual observation of fluorescent images, in two dimensions or on z-stack sections/projections, but only rarely in three dimensions (3D). Results: In the present study, we used DNA fluorescent in situ hybridization (FISH) to localize centromeric (minor satellites), pericentromeric (major satellites), and telomeric genomic sequences throughout the preimplantation period in naturally fertilized mouse embryos (from the 1-cell to blastocyst stage). Their distribution was then analyzed in 3D on confocal image stacks, focusing on the nucleolar precursor bodies and nucleoli known to evolve rapidly throughout the first developmental stages. We used computational imaging to quantify various nuclear parameters in the 3D-FISH images, to analyze the organization of compartments of interest, and to measure physical distances between these compartments. Conclusions: The results highlight differences in nuclear organization between the two parental inherited genomes at the 1-cell stage, i.e. just after fertilization. We also found that the reprogramming of the embryonic genome, which starts at the 2-cell stage, undergoes other remarkable changes during preimplantation development, particularly at the 4-cell stage.
Contient: Entre la récupération des savoirs critiques et la construction des standards du management libéral : bougés, glissements et déplacements dans la circulation des savoirs entre recherche, ...administration et politique en France de 1975 à 2005; Le débat américain sur la certification des enseignants et le piège d'une politique éducative evidence-based; L'école efficace ou l'horizon du monde comme laboratoire; La relation entre recherche et action syndicale en éducation : le cas du Québec; De nouveaux rapports entre science et politique; le cas des programmes scolaires; Entre recherche, pratique et politique : le Conseil supérieur de l'éducation au Québec, une démarche originale.
AIMSThis study sought to clarify the molecular pathways underlying the putative evolution from lymphomatoid papulosis (LyP) to cutaneous anaplastic large-cell lymphoma (c-ALCL) and lymph node ...invasion (LNI).METHODS AND RESULTSWe analysed nine sequential tumours from the same patient presenting with parallel evolution of LyP (n = 3) and c-ALCL (n = 1) with LNI (n = 1), combined with systemic diffuse large B-cell lymphoma (DLBCL) (n = 4). Clonality analysis showed a common clonal T-cell origin in the five CD30+ lesions, and a common clonal B-cell origin in the four DLBCL relapses. Array-comparative genomic hybridisation and targeted next-generation sequencing analysis demonstrated relative genomic stability of LyP lesions as compared with clonally related anaplastic large-cell lymphoma (ALCL) tumours, which showed 4q and 22q13 deletions involving the PRDM8 and TIMP3 tumour suppressor genes, respectively. The three analysed CD30+ lesions showed mostly private (specific to each sample) genetic alterations, suggesting early divergence from a common precursor. In contrast, DLBCL tumours showed progressive accumulation of private alterations, indicating late divergence.CONCLUSIONSSequential cutaneous and nodal CD30+ tumours were clonally related. This suggests that LyP, c-ALCL and LNI represent a continuous spectrum of clonal evolution emerging from a common precursor of cutaneous CD30+ lymphoproliferations. Therefore, nodal ALCL tumours in the context of LyP should be considered as a form of transformation rather than composite lymphoma.
The transfer of maternal antibodies is a critical mechanism for the early life survival of vertebrate new-borns. In mammals, passive transfer of immune compounds can occur prenatally through the ...placenta and postnatally through the consumption of colostrum and milk. In social mammals, it has been hypothe-sized that allosuckling may be a way for pups to broaden and strengthen their passive access to antibodies after birth, but empirical evidence for this mechanism is still lacking. In order to investigate the potential for the occurrence of a cross-transfer of antibodies between pups exposed to several females, we bred in a common environment groups of two females Mongolian gerbils (Meriones unguiculatus), each previously injected with a different vaccine. Here we report the dynamics of passively acquired specific antibodies in the serum of newborns, showing that pups acquired antibodies from both females of a group. Our result provides the first experimental evidence of a cross-transfer between litters of passively acquired antibodies. We discuss how such evidence opens perspectives for exploring the potential importance of horizontal transfer of immunity in natural host–parasite systems and how this could be used as a tool to answer important behavioral ecology questions.
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