Comparative Study of TPep-Like Immunoreactive Neurons in the Central Nervous System of Nudibranch Molluscs

Baltzley, Michael J.; Lohmann, Kenneth J.

doi:10.1159/000157356

Cited by 6 publications

(9 citation statements)

References 85 publications

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“…There are species differences in the total number of neurons in some of the GABA‐ir clusters in the nudibranchs including Ce ɣL and d Ce ɣPM. This is consistent with previous studies that show that while neuronal types are conserved, the exact number of neurons of that type can vary among related species (Callaway et al, ; Katz, ; Turrigiano and Selverston, ; Newcomb et al, ; Baltzley and Lohmann, ). Pd ɣ1 is bilaterally represented in Tritonia and Hermissenda , but only appears on the left pedal ganglion in Melibe and Dendronotus .…”

Section: Discussionmentioning

confidence: 99%

Comparative mapping of GABA‐immunoreactive neurons in the central nervous systems of nudibranch molluscs

Gunaratne

Sakurai

Katz

2014

J of Comparative Neurology

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The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs.

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Section: Discussionmentioning

confidence: 99%

Comparative mapping of GABA‐immunoreactive neurons in the central nervous systems of nudibranch molluscs

Gunaratne

Sakurai

Katz

2014

J of Comparative Neurology

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“…Previous studies have found that the function of neural circuits can evolve by changing neuromodulators (Fenelon et al 2004), changing neuron physiological properties (Newcomb and Katz 2007), adding neurons (Page 2002; Baltzley and Lohmann 2008), losing neurons (Espinoza et al 2006), changing neuron structures (Dacks et al 2006), and changing synaptic strengths (Chiang et al 2006). Therefore, it is not surprising that neural circuits could also evolve by changing from an excitatory chemical connection to an inhibitory one.…”

Section: Discussionmentioning

confidence: 99%

Species-specific behavioral patterns correlate with differences in synaptic connections between homologous mechanosensory neurons

2010

Self Cite

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We characterized the behavioral responses of two leech species, Hirudo verbana and Erpobdella obscura, to mechanical skin stimulation and examined the interactions between the pressure mechanosensory neurons (P cells) that innervate the skin. To quantify behavioral responses, we stimulated both intact leeches and isolated body wall preparations from the two species. In response to mechanical stimulation, Hirudo showed local bending behavior, in which the body wall shortened only on the side of the stimulation. Erpobdella, in contrast, contracted both sides of the body in response to touch. To investigate the neuronal basis for this behavioral difference, we studied the interactions between P cells. Each midbody ganglion has four P cells; each cell innervates a different quadrant of the body wall. Consistent with local bending, activating any one P cell in Hirudo elicited polysynaptic inhibitory potentials in the other P cells. In contrast, the P cells in Erpobdella had excitatory polysynaptic connections, consistent with the segment-wide contraction observed in this species. In addition, activating individual P cells caused asymmetrical body wall contractions in Hirudo and symmetrical body wall contractions in Erpobdella. These results suggest that the different behavioral responses in Erpobdella and Hirudo are partly mediated by interactions among mechanosensory cells.

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“…Here we find direct evidence for this hypothesized tradeoff. In addition, others have hypothesized that giant neurons in molluscs have arisen as an adaptive response to large synaptic fields (20,21). These cells are usually polyploid and therefore have the production capacity to supply a large number of synapses.…”

Section: Discussionmentioning

confidence: 99%

Trade-off between aerobic capacity and locomotor capability in an Antarctic pteropod

Rosenthal

Seibel²,

Dymowska³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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At ؊1.8°C, the waters of Antarctica pose a formidable physiological barrier for most ectotherms. The few taxa that inhabit this zone have presumably made specific adjustments to their neuromuscular function and have enhanced their metabolic capacity. However, support for this assertion is equivocal and the details of specific compensations are largely unknown. This can generally be attributed to the fact that most Antarctic organisms are either too distantly related to their temperate relatives to permit direct comparisons (e.g., notothenioid fishes) or because they are not amenable to neuromuscular recording. Here, as a comparative model, we take advantage of 2 pelagic molluscs in the genus Clione to conduct a broadly integrative investigation on neuromuscular adaptation to the extreme cold. We find that for the Antarctic congener aerobic capacity is enhanced, but at a cost. To support a striking proliferation of mitochondria, the Antarctic species has shed a 2-gear swim system and the associated specialized neuromuscular components, resulting in greatly reduced scope for locomotor activity. These results suggest that polar animals have undergone substantial tissue-level reorganizations to accommodate their environment, which may reduce their capacity to acclimate to a changing climate.Antarctica ͉ Clione antarctica ͉ Clione limacina ͉ temperature adaptation ͉ mitochondria C lione antarctica, which passes its complete life cycle below 0°C, and Clione limacina (Fig. 1A), normally found between Ϸ5 and 12°C in the north Atlantic and Pacific, occupy nearly identical ecological niches (1) despite their presumed separation by the circumpolar current Ͼ30 million years ago (2). They both feed exclusively on the thecosomatous pteropod Limacina helicina (3) and, although planktonic, rely on 2 wing-like parapodia for locomotion. The predatory arsenal of C. limacina, which has been studied in great detail, includes a multigeared neuromuscular swimming system that drives the parapodia to sweep through an arc of Ϸ180°(4, 5). During routine swimming, animals shift between slow (Ϸ1-2 Hz) and fast (2-5 Hz) modes, based on their wing-beat frequency (5, 6). The present study was prompted by the simple observation that C. antarctica has never been seen swimming in the fast mode (4, 6) (Movies S1-S3).For C. limacina, the cellular underpinnings of the locomotory system, and its ability to shift speeds, have been uncovered by using a reduced preparation that contains only the parapodia, the wing nerves, and the 2 pedal ganglia (Fig. 1B), structures sufficient to generate the entire swim cycle (6, 7). Neural control of swimming is generated within the pedal ganglia. A pair of interneurons establish the basic wing-beat frequency (7, 8), one controlling dorsal phase flexions of the parapodia and the other ventral phase flexions. They inhibit each other by the process of postinhibitory rebound (9). Each interneuron is connected to multiple small motoneurons that drive small fields of slowtwitch, mitochondria-rich muscle fibers in the par...

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Comparative Study of TPep-Like Immunoreactive Neurons in the Central Nervous System of Nudibranch Molluscs

Cited by 6 publications

References 85 publications

Comparative mapping of GABA‐immunoreactive neurons in the central nervous systems of nudibranch molluscs

Comparative mapping of GABA‐immunoreactive neurons in the central nervous systems of nudibranch molluscs

Species-specific behavioral patterns correlate with differences in synaptic connections between homologous mechanosensory neurons

Trade-off between aerobic capacity and locomotor capability in an Antarctic pteropod

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