Journal: Integrative Organismal Biology

Article Title: Peptidergic Modulation of the Lobster Cardiac System Has Opposing Action on Neurons and Muscles

doi: 10.1093/iob/obaf002

Figure Lengend Snippet: Physiological approaches. The modulatory effects of myosuppressin on cardiac muscle were assessed in two ways: ( A ) measuring changes in glutamate-evoked muscle contractions, and ( B ) measuring changes in the postsynaptic responses (excitatory junction potentials; EJPs) that were evoked by stimulating the terminal segment of the posterior lateral motor nerve that innervates the transverse muscle (TM). ( A ) Photograph of the dissected lobster heart that has been cut along the ventral, rostral–caudal axis to reveal the cardiac ganglion (CG) and associated cardiac muscles. The preparation was stained using methylene blue to visualize nerve and muscle tissue. A force transducer (FT) was used to measure contractions in one of the TM. Contractions were evoked in the absence of the CG (dissected out; indicated by the “X” over the CG) via focal application of glutamate (Glut, 5.5 × 10 −4 M). A representative force transducer trace is shown below the photograph with blue arrows indicating three instances of focally applied glutamate. ( B ) The same photograph used in (A) to show a schematic of how postsynaptic excitatory junction potentials (EJPs) were recorded. Similar to (A) , the CG was dissected away from the heart; however, in this approach, a segment of terminal nerve (no neurons present) was left intact so that a suction electrode (Stim.) could be used to stimulate the motor nerve. In this way, we were able to record single EJPs from the TM fibers using a sharp electrode (schematic on the right). EJPs were then amplified and recorded; an example recording is shown below the photograph with teal arrows indicating when each nerve stimulus was delivered (voltage transients are visible on the voltage trace).

Article Snippet: Glass suction electrodes pulled on a DMZ-Universal Puller (Zeitz-Instrumente Vertriebs GmbH, Planegg, Germany) were hand cut and fire polished using a microforge (MF-830 Narishige, Tokyo, Japan) to have a 100-μm opening at the tip.

Techniques: Muscles, Staining, Amplification

Journal: International Journal of Molecular Sciences

Article Title: Olfactory Projections to Locomotor Control Centers in the Sea Lamprey

doi: 10.3390/ijms25179370

Figure Lengend Snippet: Extracellular responses in the PT to electrical stimulation of the olfactory nerve, medOB, MOB, and LPal. ( A1 ) The schematic dorsal view of the isolated adult lamprey brain illustrates the rostrocaudal level at which a transverse section was made to produce the isolated forebrain preparation ( A2 ) that enables extracellular recording in the PT and electrical stimulation of the olfactory nerve ( B1 – B3 ), medOB ( C1 – C3 ), main olfactory bulb (MOB; D1 – D3 ), and lateral pallium (LPal; E1 – E3 ). ( A3 ) Photomicrograph of a transverse section at the level of the PT illustrating the extracellular recording site (white circle; tip diameter: 125 µm). Cell populations within the PT are labeled with DAPI (blue), and axonal projections of the medOB (green) are anterogradely labeled by a biocytin injection. ( B1 ) Extracellular recording in the PT shows the response evoked by electrical stimulation of the ipsilateral olfactory nerve in a representative animal. ( B2 ) In a raster plot, 25 responses from 5 newly transformed adults are aligned on the time of stimulation (time = 0 s) and summed in a vertical bar chart ( B3 , bar width: 100 ms). The spikes occurring at time = 0 s are stimulation artifacts and have not been included in the histograms. The same organization is shown with the same representative animals after the stimulation electrode was repositioned in the ipsilateral medOB ( C1 – C3 ), MOB ( D1 – D3 ), or LPal ( E1 – E3 ). Scale bar in A3: 100 µm; scale bars in E1: 50 µV and 1 s.

Article Snippet: Extracellular recordings of neural activity in the PT were performed with suction electrodes with borosilicate glass micropipettes (Sutter Instrument; 125 μm tip diameter) and filled with Ringer’s solution.

Techniques: Isolation, Labeling, Injection, Transformation Assay

Journal: International Journal of Molecular Sciences

Article Title: Olfactory Projections to Locomotor Control Centers in the Sea Lamprey

doi: 10.3390/ijms25179370

Figure Lengend Snippet: Extracellular responses in the PT to electrical stimulation of the olfactory nerve, medOB, MOB, and LPal during the bath application of gabazine. ( A1 ) The schematic dorsal view of the isolated adult lamprey brain illustrates the rostrocaudal level at which a transverse section was made to produce the isolated forebrain preparation ( A2 ) that enables extracellular recording in the PT and electrical stimulation of the olfactory nerve ( B1 – B3 ), medOB ( C1 – C3 ), MOB ( D1 – D3 ), and LPal ( E1 – E3 ). ( A3 ) Photomicrograph of a transverse section at the level of the PT illustrating the extracellular recording site (white circle; tip diameter: 125 µm). Cell populations within the PT are labeled with DAPI (blue), and axonal projections of the medOB (green) are anterogradely labeled by a biocytin injection. ( B1 ) Extracellular recording in the PT shows the amplified response evoked by electrical stimulation of the ipsilateral olfactory nerve in a representative animal during the bath application of GABA A receptor antagonists (gabazine: 10 µM). ( B2 ) In a raster plot, 25 responses from 5 newly transformed adults are aligned on the time of stimulation (time = 0 s) and summed in a vertical bar chart ( B3 , bar width: 100 ms). The spikes occurring at time = 0 s are stimulation artifacts and have not been included in the histograms. The same organization is shown with the same representative animals after the stimulation electrode was repositioned in the ipsilateral medOB ( C1 – C3 ), MOB ( D1 – D3 ), or LPal ( E1 – E3 ), all of which also evoke amplified extracellular responses in the PT. Scale bar in A3: 100 µm; scale bars in E1: 50 µV and 1 s.

Article Snippet: Extracellular recordings of neural activity in the PT were performed with suction electrodes with borosilicate glass micropipettes (Sutter Instrument; 125 μm tip diameter) and filled with Ringer’s solution.

Techniques: Isolation, Labeling, Injection, Amplification, Transformation Assay

Journal: International Journal of Molecular Sciences

Article Title: Olfactory Projections to Locomotor Control Centers in the Sea Lamprey

doi: 10.3390/ijms25179370

Figure Lengend Snippet: Electrical stimulation of the medOB produces swimming, extracellular activity in the PT, and spiking activity in RS cells. ( A1 ) Schematized representation of the semi-intact lamprey preparation showing the isolated whole brain (black frame) pinned to the bottom of the recording chamber and the intact, freely swimming body in a second, deeper compartment; adapted from . ( A2 ) The brain is schematized to show the bilateral medOB stimulation site, the PT extracellular recording site, and the reticulospinal (RS) cell intracellular recording site in the middle rhombencephalic reticular nucleus (MRRN). ( A3 ) Photograph of the dorsal view of the telencephalon with stimulation electrodes (dashed lines) bilaterally positioned in the medOBs. ( A4 ) Photomicrograph of a transverse section at the level of the olfactory bulbs showing the lesions caused by the stimulating electrodes (white dashed lines). This confirms that the tip of both stimulation electrodes was within the medOB. ( B1 – B3 ) Bilateral medOB stimulation induced episodes of swimming activity that were accompanied by neural bursts of activity in the PT and RS cell spiking. ( B1 ) Lateral displacement of a body segment was monitored with a video camera and plotted to illustrate swimming activity. Concurrently, extracellular activity was recorded in the PT ( B2 ), and RS cell activity was recorded intracellularly ( B3 ). Scale bar in ( A4 ): 100 µm; scale bar in ( B1 ): 20 mm; scale bar in ( B2 ): 100 µV; scale bars in ( B3 ): 10 mV and 5 s.

Article Snippet: Extracellular recordings of neural activity in the PT were performed with suction electrodes with borosilicate glass micropipettes (Sutter Instrument; 125 μm tip diameter) and filled with Ringer’s solution.

Techniques: Activity Assay, Isolation

Journal: International Journal of Molecular Sciences

Article Title: Olfactory Projections to Locomotor Control Centers in the Sea Lamprey

doi: 10.3390/ijms25179370

Figure Lengend Snippet: Electrical stimulation of the LPal produces swimming, extracellular activity in the PT, and spiking activity in RS cells. ( A1 ) Schematized representation of the semi-intact lamprey preparation showing the isolated whole brain (black frame) pinned to the bottom of the recording chamber and the intact, freely swimming body in a second, deeper compartment; adapted from . ( A2 ) The brain is schematized to show the bilateral LPal stimulation site, the PT extracellular recording site, and the RS cell intracellular recording site in the MRRN. ( A3 ) Photograph of the dorsal view of the telencephalon with stimulation electrodes (dashed lines) bilaterally positioned in the LPal. ( A4 ) Photomicrograph of a transverse section at the level of the LPal showing the lesion caused by the stimulating electrode (white dashed line). ( B1 – B3 ) Bilateral LPal stimulation induced episodes of swimming activity with neural bursts of activity in the PT and RS cell spiking. ( B1 ) Lateral displacement of a body segment was monitored with a video camera and plotted to illustrate swimming activity. Extracellular activity was concurrently recorded in the PT ( B2 ), and membrane potential was intracellularly recorded in an RS cell ( B3 ). Scale bar in ( A4 ): 100 µm; scale bar in ( B1 ): 20 mm; scale bar in ( B2 ): 100 µV; scale bars in ( B3 ): 10 mV and 5 s.

Article Snippet: Extracellular recordings of neural activity in the PT were performed with suction electrodes with borosilicate glass micropipettes (Sutter Instrument; 125 μm tip diameter) and filled with Ringer’s solution.

Techniques: Activity Assay, Isolation, Membrane