Antennule

FIGURE 6-16 Neuronal sensing top view of a flow cell with mounted antennule and the various electrode connections. (Reproduced with permission from reference 52.)... 

Mead, K. S., M. B. Wiley, M. A. R. Koehl, and J. R. Koseff. Fine-scale patterns of odor encounter by the antennules of mantis shrimp tracking turbulent plumes in wave-affected and unidirectional flow. J. Exp. Biol. 206, 181-193 (2003). 

In one biosensor design, the chemoreceptive nerve fibers of the antennules of the blue crab Callinectes sapidus are connected to a micropipet electrode. This assembly has been termed a receptrode (2). The receptrode created from Callinectes sapidus responds to the presence of amino acids (1) (qv) in concentrations as low as 10-9 M. 

While experimental evidence concerning the molecular mechanisms and the diversity of reaction cascades involved in olfactory signal transduction in antennal cells of insects is still fragmentary, a much more detailed picture has been established for signal transduction in chemosensory cells of the lobster, another member of the arthropod phyla. The bipolar chemosensory neurons of the lobster antennule respond to stimulation with odorous compounds either with an excitation or an inhibition i.e. cells are equipped to respond to one odor with a depolarization and excitation as well as to another odor with a hyperpolarization and inhibition. 

Instead of isolating, stabilizing, and immobilizing chemoreceptors onto electrodes, it is possible to use intact biological sensing structures for determining relevant chemical stimulants (88,89). This novel concept was illustrated with antennule structures of the blue crab. Such structures are part of the crab food-... 

Receptors can be isolated and immobilized on the transducer surface, but for the purpose a complete organelle can be employed, e.g., animal or insect antennule, or nerve fibers,132 where different sensitivity was demonstrated for various stimuli (amino acids and closely-related analogs). For comparison, the biosensor made with isolated olfactory receptor proteins, immobilized on the surface of piezoelectric crystal, exhibited sensitivity to different volatile compounds.134... 

First tissue-based biosensor antennules from blue crabs mounted in a chamber with a platinum electrode to detect amino acids [18]... 

Dissected antennule from the blue crab Callinectes sapidus) mounted in a flow apparatus and monitored by glass electrodes Neural-active compounds [66]... 

The olfactory organs of malacostracan crustaceans (e.g., lobsters, shrimp, crabs, stomatopods) are the lateral branches (called lateral filaments ) of the antennules, which bear chemosensory hairs (called aesthetascs ) (Fig. 5.1a, c, e) (reviewed by... 

Another research path also led me to crustacean antennules. Years of field research in coastal marine habitats made me realize the importance of understanding the physical environment of an organism on the spatial and temporal scales... 

Fig. 5.2 Diagram of the spiny lobster, Panulirus argus, flicking the aesthetasc-bearing lateral filaments of its olfactory antennules. Drawing by Jorge A. Varela Ramos...

A number of researchers have suggested that when malacostracan crustaceans flick the lateral filaments of their antennules, they increase the penetration of ambient water into the spaces between aesthetascs, and thus bring odor-carrying water closer to the receptor cells in those chemosensory hairs (Snow 1973 Schmitt and Ache 1979 Atema 1985 Gleeson et al. 1993 Koehl 1995, 1996). 

Early evidence for this idea was provided by Schmitt and Ache (1979), who found that the response to changes in odor concentration by olfactory receptor neurons in lobster antennules was enhanced if the antennule flicked. The idea that this enhanced response was due to improved water flow into the aesthetasc array was supported by Moore et al. (1991), who found that when they squirted water onto lobster antennules (to mimic flicking), the penetration into the aesthetasc array of tracer molecules carried in the water was increased. How does water flow through an aesthetasc array during a flick, and how does it depend on antennule morphology and motion ... 

Dynamically-Scaled Physical Models of Antennules Reveal When Fluid Flows into Arrays of Aesthetascs... 

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