Innexins in the lobster stomatogastric nervous system: cloning, phylogenetic analysis, developmental changes and expression within adult identified dye and electrically coupled neurons

Gap junctions play a key role in the operation of neuronal networks by enabling direct electrical and metabolic communication between neurons. Suitable models to investigate their role in network operation and plasticity are invertebrate motor networks, which are built of comparatively few identified neurons, and can be examined throughout development; an excellent example is the lobster stomatogastric nervous system. In invertebrates, gap junctions are formed by proteins that belong to the innexin family. Here, we report the first molecular characterization of two crustacean innexins: the lobster Homarus gammarus innexin 1 (Hg-inx1) and 2 (Hg-inx2). Phylogenetic analysis reveals that innexin gene duplication occurred within the arthropod clade before the separation of insect and crustacean lineages. Using in situ hybridization, we find that each innexin is expressed within the adult and developing lobster stomatogastric nervous system and undergoes a marked down-regulation throughout development within the stomatogastric ganglion (STG).The number of innexin expressing neurons is significantly higher in the embryo than in the adult. By combining in situ hybridization, dye and electrical coupling experiments on identified neurons, we demonstrate that adult neurons that express at least one innexin are dye and electrically coupled with at least one other STG neuron. Finally, two STG neurons display no detectable amount of either innexin mRNAs but may express weak electrical coupling with other STG neurons, suggesting the existence of other forms of innexins. Altogether, we provide evidence that innexins are expressed within small neuronal networks built of dye and electrically coupled neurons and may be developmentally regulated. © The Authors (2006)

Extra activation component of calcium release in frog muscle fibres

In addition to activating more Ca2+ release sites via voltage sensors in the t-tubular membranes, it has been proposed that more depolarised voltages enhance activation of Ca2+ release channels via a voltage-dependent increase in Ca-induced Ca2+ release (CICR). To test this, release permeability signals in response to voltage-clamp pulses to two voltages, –60 and –45 mV, were compared when Δ[Ca2+] was decreased in two kinds of experiments. (1) Addition of 8 mm of the fast Ca2+ buffer BAPTA to the internal solution decreased release permeability at –45 mV by > 2-fold and did not significantly affect Ca2+ release at –60 mV. Although some of this decrease may have been due to a decrease in voltage activation at –45 mV – as assessed from measurements of intramembranous charge movement – the results do tend to support a Ca-dependent enhancement with greater depolarisations. (2) Decreasing SR (sarcoplasmic reticulum) Ca content ([CaSR]) should decrease the Ca2+ flux through an open channel and thereby Δ[Ca2+]. Decreasing [CaSR] from > 1000 μm (the physiological range) to < 200 μm decreased release permeability at –45 mV relative to that at –60 mV by > 6-fold, an effect shown to be reversible and not attributable to a decrease in voltage activation at –45 mV. These results indicate a Ca-dependent triggering of Ca2+ release at more depolarised voltages in addition to that expected by voltage control alone. The enhanced release probably involves CICR and appears to involve another positive feedback mechanism in which Ca2+ release speeds up the activation of voltage sensors

The Burgundy Circle’s plans to undermine Louis XIV’s ‘absolute’ state through polysynody and the high nobility

Louis the duc de Bourgogne (1686 – 1712), grandson of Louis XIV, was briefly Dauphin of France before his premature death from measles. Advised by a group of noted former tutors and members of the court, Bourgogne’s Circle devised a range of plans to reform the French state under his future rule. Opposing the centralising model of sovereignty pursued by Louis XIV, the Circle intended to expand government, decentralise power into the provinces, reform an ailing economy, and resurrect the fortunes of a high-aristocracy believed to have been excluded from meaningful government. The Circle’s conviction that Louis XIV had circumvented the ancient nobility by tyrannical (‘absolutist’) means challenges revisionist interpretations of absolutism in ancien régime France. This article will therefore test revisionist claims that ‘absolutism’ did not exist in France, by assessing the contemporary opinion of the Circle’s key members. In so doing, it will reveal the divergent reform agendas of its members and contest previous historiographical notions that depict the group as possessing a cohesive ideology

Coping with voices: A group approach for managing auditory hallucinations.

This article describes a group intervention designed to help people with severe mental illnesses cope with auditory hallucinations. Each session is comprised of both a supportive discussion and skills training. The skills training component utilizes a modeling sequence to promote the development of behavioral coping strategies. These strategies are empirically derived and have been organized into a user-friendly format based on the input of persons who experience hallucinations and mental health professionals. Practical information is also provided to serve as a guide for organizing and implementing this group.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61163/1/Auditory.pd