Presynaptic dense bars at neuromuscular synapses of the lobster, Homarus americanus

C. K. Govind; R. A. De Rosa; Joanne Pearce

doi:10.1007/bf00239331

Quantitative comparison of low- and high-output neuromuscular synapses from a motoneuron of the lobster (Homarus americanus)

Cell and Tissue Research ◽

10.1007/bf00234190 ◽

1979 ◽

Vol 198 (3) ◽

Cited By ~ 22

Author(s):

C.K. Govind ◽

D.E. Meiss

Keyword(s):

Homarus Americanus ◽

Quantitative Comparison ◽

Neuromuscular Synapses ◽

High Output

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Polyneuronal innervation of an adult and embryonic lobster muscle

Development ◽

10.1242/dev.87.1.13 ◽

1985 ◽

Vol 87 (1) ◽

pp. 13-26

Author(s):

c. K. Govind ◽

Philip J. Stephens ◽

Judith S. Eisen

Keyword(s):

Homarus Americanus ◽

Inhibitory Synapses ◽

Neuromuscular Synapses ◽

Extensor Muscles ◽

Full Complement ◽

Section Electron ◽

Innervation Patterns ◽

The Common ◽

Serial Section Electron Microscopy ◽

Polyneuronal Innervation

Motor innervation of the deep extensor muscle in the abdomen of lobsters (Homarus americanus) was compared in adults and embryos using electrophysiological techniques. There is widespread innervation of the adult muscle by the common excitor and inhibitor axons and regionally restricted or private innervation by three more excitor axons. In the embryo the earliest sign of functional innervation revealed a single inhibitory and two to three excitatory axons thus denoting simultaneous innervation by the full complement of axons. In corroboration, serial-section electron microscopy revealed several axon profiles invading the embryonic deep extensor muscles and giving rise to well-defined neuromuscular synapses with presynaptic dense bars. Innervation patterns to homologous regions of the embryonic and adult muscles were similar, consisting of a few large inhibitory synapses and many small excitatory ones. Consequently the adult pattern of polyneuronal innervation occurs simultaneously and in toto during embryonic development.

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Neuromuscular synapses on the dactyl opener muscle of the lobster Homarus americanus

Cell and Tissue Research ◽

10.1007/s00441-006-0221-5 ◽

2006 ◽

Vol 326 (3) ◽

pp. 823-834

Author(s):

Jonna Hamilton ◽

Richard M. Dillaman ◽

Mary Kate Worden

Keyword(s):

Homarus Americanus ◽

Neuromuscular Synapses

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Regional Differentiation of Neuromuscular Synapses in a Lobster Receptor Muscle

Journal of Experimental Biology ◽

10.1242/jeb.79.1.99 ◽

1979 ◽

Vol 79 (1) ◽

pp. 99-114

Author(s):

DENNIS E. MEISS ◽

C. K. GOVIND

Keyword(s):

Large Amplitude ◽

Small Amplitude ◽

Homarus Americanus ◽

Membrane Properties ◽

Muscle Membrane ◽

Regional Differentiation ◽

Muscle Fibres ◽

Flexor Muscle ◽

Neuromuscular Synapses ◽

A Minor

Properties of the synapses and muscle fibres of the distal accessory flexor muscle (DAFM) were examined in the first and second walking legs of the lobster, Homarus americanus. Stimulation of the single excitor axon produces large amplitude, poorly facilitating excitatory postsynaptic potentials (EPSPs) in the distally located fibres and small amplitude, highly facilitating EPSPs in the proximally located fibres. The input resistances (Rin) of the muscle fibres were correlated with EPSP properties such that small amplitude, highly facilitating EPSPs occurred in fibres with low Rin and large amplitude, poorly facilitating EPSPs occurred in fibres with higher Rin. All muscle fibres were similar for other membrane electrical properties. Regression analyses however show a minor contribution of Rin to the size of intracellularly recorded synaptic potentials and to their facilitation properties. Thus, differences in muscle membrane properties cannot explain the observed diversity in EPSPs. Instead EPSP diversity is based on differences in transmitter output at single synaptic foci: highly facilitating synapses with low quantal release occur only on proximally located muscle fibres and poorly facilitating synapses with high release occur only on distally located ones. Thus, the EPSP diversity from the single excitor axon to the lobster DAFM is largely presynaptic in origin.

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Growth of juvenile American lobster Homarus americanus in a changing environment

Marine Ecology Progress Series ◽

10.3354/meps11854 ◽

2016 ◽

Vol 557 ◽

pp. 177-187 ◽

Cited By ~ 8

Author(s):

MD McMahan ◽

DF Cowan ◽

Y Chen ◽

GD Sherwood ◽

JH Grabowski

Keyword(s):

Homarus Americanus ◽

American Lobster ◽

Changing Environment

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Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data

Marine Ecology Progress Series ◽

10.3354/meps13302 ◽

2020 ◽

Vol 641 ◽

pp. 159-175

Author(s):

J Runnebaum ◽

KR Tanaka ◽

L Guan ◽

J Cao ◽

L O’Brien ◽

...

Keyword(s):

Habitat Suitability ◽

Mixed Model ◽

Linear Mixed Model ◽

Gulf Of Maine ◽

Homarus Americanus ◽

Management Tool ◽

American Lobster ◽

Suitable Habitat ◽

Climate Conditions ◽

Suitability Index

Bycatch remains a global problem in managing sustainable fisheries. A critical aspect of management is understanding the timing and spatial extent of bycatch. Fisheries management often relies on observed bycatch data, which are not always available due to a lack of reporting or observer coverage. Alternatively, analyzing the overlap in suitable habitat for the target and non-target species can provide a spatial management tool to understand where bycatch interactions are likely to occur. Potential bycatch hotspots based on suitable habitat were predicted for cusk Brosme brosme incidentally caught in the Gulf of Maine American lobster Homarus americanus fishery. Data from multiple fisheries-independent surveys were combined in a delta-generalized linear mixed model to generate spatially explicit density estimates for use in an independent habitat suitability index. The habitat suitability indices for American lobster and cusk were then compared to predict potential bycatch hotspot locations. Suitable habitat for American lobster has increased between 1980 and 2013 while suitable habitat for cusk decreased throughout most of the Gulf of Maine, except for Georges Basin and the Great South Channel. The proportion of overlap in suitable habitat varied interannually but decreased slightly in the spring and remained relatively stable in the fall over the time series. As Gulf of Maine temperatures continue to increase, the interactions between American lobster and cusk are predicted to decline as cusk habitat continues to constrict. This framework can contribute to fisheries managers’ understanding of changes in habitat overlap as climate conditions continue to change and alter where bycatch interactions could occur.

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