Using large-scale perturbations in gene network reconstruction

Background: Recent analysis of the yeast gene network shows that most genes have few inputs, indicating that enumerative gene reconstruction methods are both useful and computationally feasible. A simple enumerative reconstruction method based on a discrete dynamical system model is used to study how microarray experiments involving modulated global perturbations can be designed to obtain reasonably accurate reconstructions. The method is tested on artificial gene networks with biologically realistic in/out degree characteristics.Results: It was found that a relatively small number of perturbations significantly improve inference accuracy, particularly for low-order inputs of one or two genes. The perturbations themselves should alter the expression level of approximately 50-60% of the genes in the network.Conclusions: Time-series obtained from perturbations are a common form of expression data. This study illustrates how gene networks can be significantly reconstructed from such time-series while requiring only a relatively small number of calibrated perturbations, even for large networks, thus reducing experimental costs

From monoclonal antibody to gene for a neuron-specific glycoprotein in Drosophila

A monoclonal antibody (MAb24B10), derived from mice immunized with Drosophila retina, exclusively stains photoreceptor cells in the retina and their axonal projections to the optic ganglia. The antigen (Ag24B10) is a 160-kDa glycoprotein comprising about 0.8% of the retina protein. By microsequencing, 19 of the first 21 amino acids at the NH2-terminal end of the protein have been determined. Using synthetic oligonucleotide probes corresponding to a portion of this amino acid sequence, we isolated a homologous genomic clone. A partial DNA sequence of this clone, along with blot experiments on genomic DNA and RNA, indicate that this clone is part of the structural gene for Ag24B10. By in situ hybridization, the gene was localized to the tip of chromosome 3R

Corporate Purpose and the Separation of Powers

Despite its intense focus on inter-jurisdictional competition, corporate law scholarship has thus far overlooked the influence of inter-branch competition on business organizations. This Article shows how interbranch struggles for control over corporations catalyzed the advent of modern corporate law and helped propel Delaware to its dominant position in the market for corporate charters. For centuries, the legislature, judiciary, and executive vied for the decisive role in dictating the means and ends of corporations. Through the nineteenth century, competition among the branches produced a dysfunctional and volatile relationship between government and private enterprise, with each branch successively assuming a leading role in corporate oversight, only to falter under the weight of its unique structural limitations. The resulting instability ultimately proved so intolerable as to prompt the creation of an entirely new paradigm of liberalized corporate codes at the dawn of the twentieth century. Delaware’s innovation of and rigorous adherence to corporate law’s newfound separation of powers gave it a crucial, yet previously unappreciated, edge in the competition for corporate charters. Moreover, modern corporate law’s system of checks and balances curbed longstanding abuses and ushered in an equilibrium among the branches that has served as a foundation for economic growth in the United States since. Beyond illuminating a novel factor in Delaware’s ascendency, corporate law’s separation of powers poses unappreciated problems and provides preliminary solutions for the ongoing debate over corporate purpose. A growing chorus of progressive academics and policymakers has called on the government to impose and enforce corporations’ social obligations. This Article offers new grounds for skepticism towards these proposed reforms because they would jeopardize corporate law’s hardfought equilibrium among the branches by reviving the unilateralism and dysfunction that once plagued the United States’ corporate law regime. Accordingly, this Article contends that vesting the government with a proactive role in imposing and enforcing corporate purpose, whether at the state or federal level, is ill advised. Yet this Article also provides reform-minded progressives with a concrete framework for structuring an expanded power to enforce corporate purpose with minimal risk to corporate law’s separation of powers

Cardiorespiratory physiology and swimming energetics of a high-energy-demand teleost, the yellowtail kingfish (Seriola lalandi)

This study utilizes a swimming respirometer to investigate the effects of exercise and temperature on cardiorespiratory function of an active teleost, the yellowtail kingfish (Seriola lalandi). The standard aerobic metabolic rate (SMR) of S. lalandi (mean body mass 2.1·kg) ranges from 1.55·mg·min–1·kg–1 at 20°C to 3.31·mg·min–1·kg–1 at 25°C. This 2.1-fold increase in SMR with temperature is associated with a 1.5-fold increase in heart rate from 77 to 117·beats·min–1, while cardiac stroke volume remains constant at 0.38·ml beat–1·kg–1 and the difference in oxygen content between arterial and mixed venous blood [(CaO2–CvO2)] increases marginally from 0.06 to 0.08·mg·ml–1. During maximal aerobic exercise (2.3·BL·s–1) at both temperatures, however, increases in cardiac output are limited to about 1.3-fold, and increases in oxygen consumption rates (up to 10.93·mg·min–1·kg–1 at 20°C and 13.32·mg·min–1·kg–1 at 25°C) are mediated primarily through augmentation of (CaO2–CvO2) to 0.29·mg·ml–1 at 20°C and 0.25·mg·ml–1 at 25°C. It seems, therefore, that the heart of S. lalandi routinely works close to its maximum capacity at a given temperature, and changes in aerobic metabolism due to exercise are greatly reliant on high blood oxygen-carrying capacity and (CaO2–CvO2). Gross aerobic cost of transport (GCOT) is 0.06·mg·kg–1·BL–1 at 20°C and 0.09·mg·kg–1·BL–1 at 25°C at the optimal swimming velocities (Uopt) of 1.2·BL·s–1 and 1.7·BL·s–1, respectively. These values are comparable with those reported for salmon and tuna, implying that the interspecific diversity in locomotor mode (e.g. subcarangiform, carangiform and thunniform) is not concomitant with similar diversity in swimming efficiency. A low GCOT is maintained as swimming velocity increases above Uopt, which may partly result from energy savings associated with the progressive transition from opercular ventilation to ram ventilation.T. D. Clark and R. S. Seymou