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  • 1
    Electronic Resource
    Electronic Resource
    Structure of the aesthetasc (olfactory) sensilla of the blue crab, Callinectes sapidus: transformations as a function of salinity (1996)
    Springer
    Cell & tissue research 284 (1996), S. 279-288 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Aesthetasc ; Chemoreception ; Dendrite Blue crab ; growth ; Olfaction ; Salinity adaptation ; Sensilla ; Callinectes sapidus (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The aesthetasc sensilla of the euryhaline blue crab, Callinectes sapidus, are innervated by the dendrites of from 40 to 160 bipolar chemosensory neurons. Each dendrite forms two cilia within the basal portion of the sensillum, and these subsequently branch yielding approximately 10 outer dendritic segments per neuron. Auxiliary cells surround the inner dendritic segments and also ensheathe the outer dendritic segments up to the terminus of the ”constricted region” (a zone in which there is a slight narrowing of the aesthetasc). Crystal violet staining suggesting access of odor stimuli is limited to that portion of the sensillum distal to the constricted region. In freshwater-acclimated blue crabs the length and level of branching in the dendrites extending beyond the constricted region is significantly reduced relative to that of seawater-acclimated animals (mean lengths: 150 µm versus 517 µm, respectively). After transfer of freshwater-acclimated crabs to seawater there is a rapid increase in length of the outer dendritic segments, reaching 60% of that for seawater-acclimated crabs by 48 h. A similar time course for regrowth is seen for seawater-acclimated crabs in which the outer dendritic segments have been osmotically ablated. Conversely, with rapid transfer of seawater-acclimated animals to lower salinities, there is a correspondingly rapid reduction in length of the outer dendritic segments. The reduced length of the outer dendritic segments in freshwater-acclimated animals may reflect the effective distance over which an appropriate osmotic/ionic microenvironment for neural function can be maintained within the aesthetasc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050588
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  • 2
    Electronic Resource
    Electronic Resource
    Ecto-ATPase/phosphatase activity in the olfactory sensilla of the spiny lobster, Panulirus argus: localization and characterization (1992)
    Springer
    Cell & tissue research 269 (1992), S. 439-445 
    Details
    ISSN: 1432-0878
    Keywords: Aesthetasc ; Adenosine triphosphate ; Cerium phosphate ; Cytochemistry ; Ectonucleotidase (Crustacea) ; Olfactory system ; Phosphatase ; Panulirus argus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electrophysiological studies have shown that the olfactory organ (antennule) of the spiny lobster, Panulirus argus, has chemoreceptors that are selectively excited by adenine nucleotides in seawater. Biochemical studies have revealed that these same nucleotides can be rapidly dephosphorylated by ectoenzymes associated with the olfactory sensilla (aesthetascs). In this study the distribution of ecto-ATPase/phosphatase activity within aesthetascs was determined cytochemically and the nature of the adenine-nucleotide dephosphorylating activity was dissected biochemically. Cytochemically, the distribution of ATP-dephosphorylating activity was similar to that shown previously for AMP and β-glycerol phosphate; i.e., cerium phosphate reaction product was specifically localized to the transitional zone where the sensory dendrites develop cilia and branch to form the outer dendritic segments. Unlike the dephosphorylation of AMP and β-glycerol phosphate, Mg2+ or Ca2+ was required for ecto-ATPase/phosphatase activity. Biochemical measures of both AMP-and ATP-dephosphorylating activity within aesthetascs corroborated the cytochemical evidence that these activities are localized to the transitional zone. A major portion of the AMP dephosphorylation (about 67%) derives from nonspecific alkaline phosphatase activity that is insensitive to levamisole and L-bromotetramisole. In contrast, nonspecific phosphatase activity accounted for a much smaller part of the ATP dephosphorylation (about 15%). Ectoenzymatic activity in the transitional zone may be an important means of removing excitatory/inhibitory nucleotides from this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353899
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  • 3
    Electronic Resource
    Electronic Resource
    Localization of 5′-ectonucleotidase/phosphatase activity within the olfactory sensilla of the spiny lobster, Panulirus argus (1991)
    Springer
    Cell & tissue research 265 (1991), S. 385-391 
    Details
    ISSN: 1432-0878
    Keywords: Aesthetasc ; Adenosine monophosphate ; Cerium phosphate ; Cytochemistry ; Ectonucleotidase ; Olfactory system ; Phosphatase ; Panulirus argus (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous electrophysiological studies have shown that the olfactory organ (antennule) of the spiny lobster, Panulirus argus, has external chemoreceptors, which are selectively stimulated by adenosine 5′-monophosphate (AMP) when present in seawater. Subsequent biochemical investigations revealed that AMP can be rapidly dephosphorylated by 5′-ectonucleotidase/phosphatase activity associated with the olfactory sensilla (aesthetascs). In this study the deposition of cerium phosphate was used to examine the ultrastructural distribution of 5′-ectonucleotidase/phosphatase activity in aesthetascs. Utilizing AMP as substrate, we found dephosphorylating activity to be associated with the outer membranes of both dendrites and auxiliary cells. Moreover, this activity was specifically localized to a narrow band that approximately corresponds to the transitional zone where dendrites develop cilia and branch extensively to form the outer dendritic segments. A similar distribution of the cerium phosphate reaction product was found when β-glycerol phosphate was substituted for AMP. The alkaline-phosphatase inhibitor, levamisole, had no apparent effect on the deposition of reaction product when either AMP or β-glycerol phosphate was used as substrate. The ectoenzymatic activity in the transitional zone may be of importance in clearing exogenous chemoexcitatory nucleotides from this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398087
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  • 4
    Electronic Resource
    Electronic Resource
    Sustaining olfaction at low salinities: evidence for a paracellular route of ion movement from the hemolymph to the sensillar lymph in the olfactory sensilla of the blue crab Callinectes sapidus (2000)
    Springer
    Cell & tissue research 301 (2000), S. 423-431 
    Details
    ISSN: 1432-0878
    Keywords: Aesthetasc Chemoreception Salinity adaptation Ion-selective electrode Olfaction Lanthanum Callinectes sapidus (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Evidence reported previously suggests that in low-salinity conditions the integrity of the olfactory dendrites of the blue crab is sustained by a diffusion-generated ionic microenvironment within the aesthetascs. Diffusion of ions from the hemolymph to the sensillar lymph is proposed to maintain this microenvironment. In this study, using lanthanum as an electron-dense marker of extracellular fluid space, we find morphological evidence for paracellular continuity between the hemolymph and the sensillar lymph. Lanthanum penetrates extracellular fluid spaces within the aesthetascs when antennules are either perfused or bathed externally with solutions containing lanthanum nitrate. This was found in both freshwater- and seawater-acclimated animals. Evidence for ion diffusion from the aesthetascs was obtained using self-referencing, ion-selective microelectrodes. Both Ca2+ and K+ exhibit outwardly directed flux gradients associated with the aesthetasc tuft in low-salinity conditions. These findings are consistent with the concept that ion diffusion from the hemolymph to the sensillar lymph generates an ionic/osmotic microenvironment within the aesthetascs at low salinities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410000246
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  • 5
    Electronic Resource
    Electronic Resource
    Amyloplasts from cortical root cells of Spiranthoideae (Orchidaceae) (1993)
    Springer
    Protoplasma 172 (1993), S. 49-55 
    Details
    ISSN: 1615-6102
    Keywords: Amyloplast ; Cortex ; Orchidaceae ; Root ; Spiranthoideae ; Spiranthosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cortical root cells of orchids belonging to subfamily Spiranthoideae contain globular organelles which, through chemical tests and examination with both light, scanning, and transmission electron microscopes, appear to be unique in Orchidaceae and unreported in plants in general. It is suggested these are specialized amyloplasts (spiranthosomes) and with other features may serve to characterize the spiranthoid orchid subfamily.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403721
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