Common Genetic Denominators for Ca++-Based Skeleton in Metazoa: Role of Osteoclast-Stimulating Factor and of Carbonic Anhydrase in a Calcareous Sponge

Calcium-based matrices serve predominantly as inorganic, hard skeletal systems in Metazoa from calcareous sponges [phylum Porifera; class Calcarea] to proto- and deuterostomian multicellular animals. The calcareous sponges form their skeletal elements, the spicules, from amorphous calcium carbonate (ACC). Treatment of spicules from Sycon raphanus with sodium hypochlorite (NaOCl) results in the disintegration of the ACC in those skeletal elements. Until now a distinct protein/enzyme involved in ACC metabolism could not been identified in those animals. We applied the technique of phage display combinatorial libraries to identify oligopeptides that bind to NaOCl-treated spicules: those oligopeptides allowed us to detect proteins that bind to those spicules. Two molecules have been identified, the (putative) enzyme carbonic anhydrase and the (putative) osteoclast-stimulating factor (OSTF), that are involved in the catabolism of ACC. The complete cDNAs were isolated and the recombinant proteins were prepared to raise antibodies. In turn, immunofluorescence staining of tissue slices and qPCR analyses have been performed. The data show that sponges, cultivated under standard condition (10 mM CaCl2) show low levels of transcripts/proteins for carbonic anhydrase or OSTF, compared to those animals that had been cultivated under Ca2+-depletion condition (1 mM CaCl2). Our data identify with the carbonic anhydrase and the OSTF the first two molecules which remain conserved in cells, potentially involved in Ca-based skeletal dissolution, from sponges (sclerocytes) to human (osteoclast)

Procrastination in Teams, Contract Design and Discrimination

We study a dynamic model of team production with moral hazard. We show that the players begin to invest effort only shortly before the time limit when the reward for solving the task is shared equally. We explore how the team can design contracts to mitigate this form of procrastination and show that the second-best optimal contract is discriminatory. We investigate how limited liability or the threat of sabotage influences the team’s problem. It is further shown that players who earn higher wages can be worse off than teammates with lower wages and that present-biased preferences can mitigate procrastination

Persistence of Monopoly and Research Specialization

We examine the persistence of monopolies in markets with innovations when the outcome of research is uncertain. We show that for low success probabilities of research, the incumbent can seldom preempt the potential entrant. Then the efficiency effect outweighs the replacement effect. It is vice versa for high probabilities. Moreover, the incumbent specializes in “safe” research and the potential entrant in “risky” research. We also show that the probability of entry has an inverted U-shape in the success probability. Since even at the peak entry is rather unlikely, the persistence of the monopoly is high

Entry and Incumbent Innovation

We explore how the threat of entry influences the innovation activity of an incumbent. We show that the incumbent’s investment is hump-shaped in the entry threat. When the entry threat is small and increases, the incumbent invests more to deter entry, or to make it unlikely. This is due to the entry deterrence effect. However, when the threat becomes huge, entry can no longer profitably be deterred or made unlikely and the investment becomes small. Then the Schumpeterian effect dominates. These results turn out to be very robust

Increasing Workload in a Stochastic Environment

We show that a steeply increasing workload before a deadline is compatible with time-consistent preferences. The key departure from the literature is that we consider a stochastic environment where success of effort is not guaranteed

Working conditions and regulation

Do employers invest sufficiently in the working conditions of employees? We examine this question in a simple principal-agent model. We show that, even though investment is contractible, the principal underinvests whenever her agent's alternatives are rather poor. This provides a reason for regulation. The indirect regulatory approach of taking measures that improve the agent's bargaining power or outside option at least weakly enhances the agent's well-being and welfare. The direct regulatory approach of demanding a certain standard of working conditions increases the principal's investment, but may nonetheless leave the agent's well-being unaffected and deteriorate welfare. This holds true since due to a standard, the principal may provide the agent with a lower-powered incentive scheme and implement a lower effort level