Early Development of Mouse Embryos Null Mutant for the Cyclin A2 Gene Occurs in the Absence of Maternally Derived Cyclin A2 Gene Products

AbstractProgression through the mammalian cell cycle is regulated by the sequential activation and inactivation of the cyclin-dependent kinases. In adult cells, cyclin A2-dependent kinases are required for entry into S and M phases, completion of S phase, and centrosome duplication. However, mouse embryos lacking the cyclin A2 gene nonetheless complete preimplantation development, but die soon after implantation. In this report, we investigated whether a contribution of maternal cyclin A2 mRNA and protein to early embryonic cell cycles might explain these conflicting observations. Our data show that a maternal stock of cyclin A2 mRNA is present in the oocyte and persists after fertilization until the second mitotic cell cycle, when it is degraded to undetectable levels coincident with transcriptional activation of the zygotic genome. A portion of maternally derived cyclin A2 protein is stable during the first mitosis and persists in the cytoplasm, but is completely degraded at the second mitosis. The ability of cyclin A2-null mutants to develop normally from the four-cell to the postimplantation stage in the absence of detectable cyclin A2 gene product indicates therefore that cyclin A2 is dispensable for cellular progression during the preimplantation nongrowth period of mouse embryo development

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

C-Nap1 mutation affects centriole cohesion and is associated with a Seckel-like syndrome in cattle

Caprine-like Generalized Hypoplasia Syndrome (SHGC) is an autosomal-recessive disorder in Montbéliarde cattle. Affected animals present a wide range of clinical features that include the following: delayed development with low birth weight, hind limb muscular hypoplasia, caprine-like thin head and partial coat depigmentation. Here we show that SHGC is caused by a truncating mutation in the CEP250 gene that encodes the centrosomal protein C-Nap1. This mutation results in centrosome splitting, which neither affects centriole ultrastructure and duplication in dividing cells nor centriole function in cilium assembly and mitotic spindle organization. Loss of C-Nap1-mediated centriole cohesion leads to an altered cell migration phenotype. This discovery extends the range of loci that constitute the spectrum of autosomal primary recessive microcephaly (MCPH) and Seckel-like syndromes

The Single Economic Entity Doctrine and Corporate Group Responsibility in European Antitrust Law, by Nada Ina Pauer

No abstract available

Leniency and individual liability, Oopening the 'black box' of the cartel

The purpose of this article is to examine the interplay between two competition policy enforcement instruments - leniency policy and individual liability, by opening the ‘black box’ of the cartel, with the analysis of interactions both among the cartel members and within each company. The interplay of these instruments translates into a two-dimensional system: the horizontal dimension is formed by the cartel members; the vertical one by the interactions within each cartel member. We base our analysis on the theory of the firm, advocating the separation of ownership and control, and on the theory of agency that states the principles of inherent moral hazard problems between the principal (owner) and the agent (manager). The reasoning is carried out along economic and legal literature on collusive agreements, leniency programmes and individual liability. The economic literature also gives key insights on corporate governance issues that are relevant in cartels, through game theoretical approaches. Theoretical insights will help us to understand why cartel activity is a matter of agency and governance issues. The subsequent section will be dedicated to the examination of individual liability and corporate leniency policy, in the light of agency issues. Individual leniency policy will be assessed in the last section. Individual leniency programmes are in practice never used by individuals of companies of a cartel. Nonetheless, such programmes are efficient in the way they undermine both the relations between cartel members and those inside the companies. We show how opening the ‘black box’ of the cartel is of primary importance when assessing the efficiency of leniency and individual liability. Agency issues shape the interactions between actors operating in both dimensions of the system under consideration, which are the principals and the agents of the firms of the cartel

Market power in online search and social-networking: a matter of two-sided markets

The online-search and social-networking industries are characterized by the concentration of large market shares among a very limited number of actors. Being advertisement-based media, search engines and social-networking websites fall within the category of special types of markets known as two-sided markets or platforms. Two-sided markets or platforms have two distinct user groups which produce network benefits for each other. The platforms enable the user groups to minimize the transaction costs they would otherwise incur, in interacting with or searching for each other. Competition authorities cannot ignore the economics of two-sided markets in assessing market power in the search and social networking industries. This paper provides a framework for defining the relevant market and for assessing market power in the industries of online search and social-networking websites, focusing on the current leaders Google and Facebook and argues that online-search and social-networking websites may exert competitive constraints on each other, as they both operate in the relevant market for ‘monetization of user’s information by online advertising’

Antitrust v. anti-corruption policy approaches to compliance: why such a gap?

One of the striking differences between competition law and anti-corruption is the manner in which agencies take into account the compliance efforts of companies in the context of their investigations. The European Commission and the U.S. Department of Justice Antitrust Division  refuse to consider compliance programs as mitigating factors in antitrust infringements. The French and U.K. competition authorities may grant a maximum of 10 percent reduction in fines for having effective compliance measures. In contrast, in the area of anti-corruption, companies in some of the same jurisdictions can escape liability completely for having implemented “adequate procedures.” This paper explores possible reasons for such a gap in policy approaches

Market power in online search and social-networking: a matter of two-sided markets

The online-search and social-networking industries are characterized by the concentration of large market shares among a very limited number of actors. Being advertisement-based media, search engines and social-networking websites fall within the category of special types of markets known as two-sided markets or platforms. Two-sided markets or platforms have two distinct user groups which produce network benefits for each other. The platforms enable the user groups to minimize the transaction costs they would otherwise incur, in interacting with or searching for each other. Competition authorities cannot ignore the economics of two-sided markets in assessing market power in the search and social networking industries. This paper provides a framework for defining the relevant market and for assessing market power in the industries of online search and social-networking websites, focusing on the current leaders Google and Facebook and argues that online-search and social-networking websites may exert competitive constraints on each other, as they both operate in the relevant market for ‘monetization of user’s information by online advertising’

Antitrust v. anti-corruption policy approaches to compliance: why such a gap?

One of the striking differences between competition law and anti-corruption is the manner in which agencies take into account the compliance efforts of companies in the context of their investigations. The European Commission and the U.S. Department of Justice Antitrust Division  refuse to consider compliance programs as mitigating factors in antitrust infringements. The French and U.K. competition authorities may grant a maximum of 10 percent reduction in fines for having effective compliance measures. In contrast, in the area of anti-corruption, companies in some of the same jurisdictions can escape liability completely for having implemented “adequate procedures.” This paper explores possible reasons for such a gap in policy approaches