Gross Dissection of the Stomach of the Lobster, Homarus Americanus

The stomach of the American lobster (Homarus americanus) is located in the cephalothorax, between the rostrum and the cervical groove. The anterior end of the stomach is defined by the mouth opening and the posterior end by the bottom of the pylorus. Along the dorsal side of the stomach lies the stomatogastric nervous system (STNS). This nervous system, which contains rhythmic networks that underlie feeding behavior, is an established model system for studying rhythm generating networks and neuromodulation 1,2. While it is possible to study this system in vivo 3, the STNS continues to produce its rhythmic activity when isolated in vitro. In order to study this system in vitro the stomach must be removed from the animal. This video article describes how the stomach can be dissected from the American lobster. In an accompanying video article4 we demonstrate how the STNS can be isolated from the stomach

Homarus Americanus Stomatogastric Nervous System Dissection

With the goal of understanding how nervous systems produce activity and respond to the environment, neuroscientists turn to model systems that exhibit the activity of interest and are accessible and amenable to experimental methods. The stomatogastric nervous system (STNS) of the American lobster (Homarus americanus; also know was the Atlantic or Maine lobster) has been established as a model system for studying rhythm generating networks and neuromodulation of networks. The STNS consists of 3 anterior ganglia (2 commissural ganglia and an oesophageal ganglion), containing modulatory neurons that project centrally to the stomatogastric ganglion (STG). The STG contains approximately 30 neurons that comprise two central pattern generating networks, the pyloric and gastric networks that underlie feeding behaviors in crustaceans1,2. While it is possible to study this system in vivo3, the STNS continues to produce its rhythmic activity when isolated in vitro. Physical isolation of the STNS in a dish allows for easy access to the somata in the ganglia for intracellular electrophysiological recordings and to the nerves of the STNS for extracellular recordings. Isolating the STNS is a two-part process. The first part, dissecting the stomach from the animal, is described in an accompanying video article4. In this video article, fine dissection techniques are used to isolate the STNS from the stomach. This procedure results in a nervous system preparation that is available for electrophysiological recordings

Coregulation of Ion Channel Conductances Preserves Output in a Computational Model of a Crustacean Cardiac Motor Neuron

This item also falls under Society for Neuroscience copyright. For more information, please visit http://www.jneurosci.org/cgi/content/full/30/25/8637?maxtoshow=&hits=10&RESULTFORMAT=1&author1=nair&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT&eaf . Link active as of 1/29/2011. Link maintenance is the responsibility of the Society for Neuroscience.Digital Object Identifier 10.1523/JNEUROSCI.6435-09.2010Similar activity patterns at both neuron and network levels can arise from different combinations of membrane and synaptic conductance values. A strategy by which neurons may preserve their electrical output is via cell type-dependent balances of inward and outward currents. Measurements of mRNA transcripts that encode ion channel proteins within motor neurons in the crustacean cardiac ganglion recently revealed correlations between certain channel types. To determine whether balances of intrinsic currents potentially resulting from such correlations preserve certain electrical cell outputs, we developed a nominal biophysical model of the crustacean cardiac ganglion using biological data. Predictions from the nominal model showed that coregulation of ionic currents may preserve the key characteristics of motor neuron activity. We then developed a methodology of sampling a multidimensional parameter space to select an appropriate model set for meaningful comparison with variations in correlations seen in biological datasets

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Correlations in ion channel mRNA in rhythmically active neurons.

BACKGROUND:To what extent do identified neurons from different animals vary in their expression of ion channel genes? In neurons of the same type, is ion channel expression highly variable and/or is there any relationship between ion channel expression that is conserved? METHODOLOGY/PRINCIPAL FINDINGS:To address these questions we measured ion channel mRNA in large cells (LCs) of the crab cardiac ganglion. We cloned a calcium channel, caco, and a potassium channel, shaker. Using single-cell quantitative PCR, we measured levels of mRNA for these and 6 other different ion channels in cardiac ganglion LCs. Across the population of LCs we measured 3-9 fold ranges of mRNA levels, and we found correlations in the expression of many pairs of conductances CONCLUSIONS/SIGNIFICANCE:In previous measurements from the crab stomatogastric ganglion (STG), ion channel expression was variable, but many pairs of channels had correlated expression. However, each STG cell type had a unique combination of ion channel correlations. Our findings from the crab cardiac ganglion are similar, but the correlations in the LCs are different from those in STG neurons, supporting the idea that such correlations could be markers of cell identity or activity

Spontaneous activity of the cardiac ganglion in <i>C. borealis</i>.

<p>Top: intracellular recording from the axon of a LC. Bottom: simultaneous extracellular recording from the cardiac ganglion trunk, showing small cell (small units) and large cell (LC) (tall units) bursts of action potentials.</p

Example ion channel mRNA profiles from 3 groups of LCs.

<p>All cells in each group are processed together; these LCs were randomly selected among the cells with measurements for each transcript.</p