Physiology as a caste-defining feature

Division of labour is a key factor in the ecological success of social insects. Groups of individuals specializing on a particular behaviour are known as castes and are usually distinguished by morphology or age. Physiology plays a key role in both these types of caste, in either the developmental physiology which determines morphology, or the temporal changes in physiology over an insect’s life. Physiological correlates of morphological or temporal caste include differences in gland structure, secretory products, leanness, neuroanatomy and neurochemistry. However, purely physiological castes could also occur. Physiological castes are discrete groups of same-age same-size individuals with particular physiological competencies, or groups of individuals with similar physiology crossing age or size groups. A stable physiological caste occurs in the monomorphic Pharaoh’s ant, where some ants can detect old pheromone trails and retain this specialization over time. These ants differ physiologically from other workers, and the differences arise before eclosion. More temporary physiological castes occur in the ant Ectatomma where brood care specialists have more developed ovarioles than other same-aged workers, and in the honeybee where nurses, wax-workers and soldiers all differ physiologically from same-aged nestmates. Physiology is an important aspect of caste, not only in its contribution to age-related and morphological castes, but also in its own right as a caste grouping factor. While age and morphological differences make caste structures accessible for study, more cryptic physiological castes may play just as important a role in division of labour. Received 19 December 2007; revised 24 July and 18 September 2008; accepted 19 September 2008.     

PATHLOGIC-S: A Scalable Boolean Framework for Modelling Cellular Signalling

Curated databases of signal transduction have grown to describe several thousand reactions, and efficient use of these data requires the development of modelling tools to elucidate and explore system properties. We present PATHLOGIC-S, a Boolean specification for a signalling model, with its associated GPL-licensed implementation using integer programming techniques. The PATHLOGIC-S specification has been designed to function on current desktop workstations, and is capable of providing analyses on some of the largest currently available datasets through use of Boolean modelling techniques to generate predictions of stable and semi-stable network states from data in community file formats. PATHLOGIC-S also addresses major problems associated with the presence and modelling of inhibition in Boolean systems, and reduces logical incoherence due to common inhibitory mechanisms in signalling systems. We apply this approach to signal transduction networks including Reactome and two pathways from the Panther Pathways database, and present the results of computations on each along with a discussion of execution time. A software implementation of the framework and model is freely available under a GPL license.     

Cellular energetics as a target for tumor cell elimination

Investigation of cancer cell metabolism has revealed variability of the metabolic profiles among different types of tumors. According to the most classical model of cancer bioenergetics, malignant cells primarily use glycolysis as the major metabolic pathway and produce large quantities of lactate with suppressed oxidative phosphorylation even in the presence of ample oxygen. This is referred to as aerobic glycolysis, or the Warburg effect. However, a growing number of recent studies provide evidence that not all cancer cells depend on glycolysis, and, moreover, oxidative phosphorylation is essential for tumorigenesis. Thus, it is necessary to consider distinctive patterns of cancer metabolism in each specific case. Chemoresistance of cancer cells is associated with decreased sensitivity to different types of antitumor agents. Stimulation of apoptosis is a major strategy for elimination of cancer cells, and therefore activation of mitochondrial functions with direct impact on mitochondria to destabilize them appears to be an important approach to the induction of cell death. Consequently, the design of combination therapies using acclaimed cytotoxic agents directed to induction of apoptosis and metabolic agents affecting cancer cell bioenergetics are prospective strategies for antineoplastic therapy.     

Directional Reaching for Water as a Cortex-Dependent Behavioral Framework for Mice

1. Download high-res image (239KB)
2. Download full-size image

     

A Framework for Australian Studies: Some Reflections on Community,Class and Culture

Community studies as a form of study in complex societies cart be unduly restrictive though this need not be the case. It depends on the criteria employed to select a field location, and on the types of social organization studied within that location. These themes are illustrated by reference to the Australian community studies of Ron Wild and Harry Oxley. Some limitations in their studies are noted only in order to illustrate how their work might have been linked profitably with debates in Australian historiography over issues of class culture, ideology and consciousness. I propose a framework for Australian community studies that would allow anthropologists to explore some of the themes introduced in this discussion.     

The Sustainability Balanced Scorecard as a Framework for Eco-efficiency Analysis

To provide valuable support for successful decision-making, managers need a balanced set of financial and nonfinancial measures that represent different requirements, strategic goals, strategies, resources, and capabilities and the causal relationships between these domains. The balanced scorecard is such a measurement system. As an open system the balanced scorecard facilitates the consideration of sustainability issues. But enhanced balanced scorecards require a new type of data. This is where eco-efficiency analysis comes into play.
This article discusses the relationship between so-called sustainability balanced scorecards and eco-efficiency analysis. Eco-efficiency analysis not only provides a data source for sustainability balanced scorecards; in the perspective of environmental information systems it also serves as a link between the balanced scorecard and corporate environmental accounting systems so that eco-efficiency as a component of an environmental information system becomes an adapter with two interfaces, which are characterized in this article. The main focus is on the principle of cause and effect, its different forms, and the implications for the design of appropriate information system components.     

Reflections on VDAC as a voltage-gated channel and a mitochondrial regulator

There is excellent agreement between the electrophysiological properties and the structure of the mitochondrial outer membrane protein, VDAC, ex vivo. However, the inference that the well-defined canonical “open” state of the VDAC pore is the normal physiological state of the channel in vivo is being challenged by several lines of evidence. Knowing the atomic structure of the detergent solubilized protein, a long sought after goal, will not be sufficient to understand the functioning of this channel protein. In addition, detailed information about VDAC’s topology in the outer membrane of intact mitochondria, and the structural changes that it undergoes in response to different stimuli in the cell will be needed to define its physiological functions and regulation.