Rolf Elofsson

Is nitric oxide (NO) produced by invertebrate neurones

NADPH-diaphorase (NADPHd) is known to be identical to nitric oxide (NO) synthase in the mammalian nervous system, and is therefore used as a marker of NO-producing neurones. Using the histochemical reaction for NADPHd, we searched for such neurones in a selection of invertebrates. Special emphasis was given to molluscs. No selective neuronal staining was found in representatives of coelenterates, turbellarians, nematodes and urochordates. In all annelids, arthropods and molluscs examined, with the exception of a chiton, specific neurones were selectively stained. The reaction was particularly strong in pulmonate molluscs where scattered positive neurones were found in various ganglia and clustered symmetrically in the paired buccal ganglia. Biochemical assay of NO synthase in osphradia of the gastropod mollusc Lymnaea stagnalis revealed a formation of citrullin that was inhibited by the specific NO synthase N omega-nitro-L-arginine (NO2Arg). Both histochemical and biochemical methods indicate that NO can be used as a signal molecule by specific neurones in advanced invertebrates.

Identification and quantitative measurements of biogenic amines and DOPA in the central nervous system and haemolymph of the crayfish Pacif ast acus leniusculus (crustacea)

Abstract 1. The biogenic amines dopamine (DA), noradrenaline (NA), octopamine (OA), serotonin (5-HT) and the amino acid dihydroxyphenylalanine (DOPA) have been identified and quantitatively measured in the crayfish nervous system and in haemolymph employing high performance liquid chromatography (HPLC). 2. The substances occurred in the nervous system in amounts ranging between 0.1 and 0.7 μg/g w/w. 3. The haemolymph contained very small amounts of NA, OA, 5-HT and DOPA. 4. No adrenaline (A) was present. 5. Prolonged handling of the animals caused dramatic changes in DOPA levels. 6. Depletion experiments using reserpine caused a pronounced decrease in the content of DA, NA, OA and 5-HT in the nervous system. DOPA, however, remained unaffected.

The nauplius eye and frontal organs of the non-Malacostraca (Crustacea)

Abstract The present work is a continuation of the morphological studies of the nauplius eye and frontal organs of the Crustacea. The previous papers on this topic comprised the Decapoda (ELOFSSON, 1963) and the Malacostraca (ELOFSSON, 1965). Its has been found that the nauplius eye and frontal organs of the Crustacea are separated into four different types. These comprise the Phyl-lopoda, Anostraca, Maxillipoda-Ostracoda and Malacostraca. Frontal organs do not appear in the maxillopod-ostracod group, but are present as paired dorsal and ventral frontal organs in the Malacostraca, paired ventral frontal organ in the Anostraca, and paired distal and unpaired posterior medial frontal organ in the Phyllopoda. The frontal organs of the different groups are not homologous. Their nature as reduced frontal eyes is maintained. The nauplius eye (and frontal organs when present and developed as eyes) shows, for instance, the following dissimilarities. The sensory cells of the eyes of the Malacostraca are everse wit...

5-HT-like immunoreactivity in the central nervous system of the crayfish, Pacifastacus leniusculus

SummaryAn immunocytochemical technique with the use of three different antibodies raised against serotonin was applied to localize the immunoreactive neurons in the central nervous system of the crayfish, Pacifastacus leniusculus. Immunoreactive neurons were found in three optic ganglia (medulla externa, interna and terminalis). They appeared in three layers of the medulla externa and interna. The medulla terminalis displayed three prominent groups of immunoreactive perikarya and mainly marginal immunoreactive fibres. Immunoreactive areas of the brain comprised the protocerebral bridge, central body, paracentral lobes and two loci in the anterior portion of the protocerebrum, i.e., the terminal areas for immunoreactive fibres from the optic centres. The olfactory lobes showed a specific immunoreactive pattern. In addition, diffusely and sparsely distributed immunoreactive fibres were found throughout the brain. The immunoreactive neurons are largely localized in the same areas of the central nervous system as the catecholaminergic neurons although some distinct differences occur.

Monoamine-containing neurons in the optic ganglia of crustaceans and insects

SummaryWith the fluorescence method of Falck and Hillarp, the presence and localization of monoaminergic neurons in the optic ganglia of several crustaceans and insects have been investigated. It was found that in both classes the monoaminergic terminals, when present, appeared (especially in the medullae externa and interna of the crustaceans and the medulla of the insects) in strata specific for each species. So far, the only monoamine (visualized by this technique) present in the crustacean optic ganglia is dopamine, whereas in the Insecta, the catecholamines dopamine and noradrenaline, and the indolamine, 5-hydroxytryptamine, are found in the optic lobe. But in the Insecta, different species show different content of these amines.

The Optic Neuropiles and Chiasmata of Crustacea

SummaryOn the basis of ontogeny and adult morphology, an interpretation of the arrangement of optic neuropiles and fibre connexions of the Crustacean compound eye is presented. In the embryo of phyllopods and decapods, the ommatidia, the lamina ganglionaris, and the medulla externa are developed synchronously from a common medial proliferation zone. As this zone persists in all investigated adult Crustacea that possess compound eyes, such a derivation of the mentioned structures is taken to be universal within the group. The direction of growth of the lamina ganglionaris is parallel with the row of ommatidia, the growth direction of the medulla externa is perpendicular to it and parallel with the long axis of the eyestalk. This arrangement is more or less retained in most adult non-Malacostracan Crustacea, and the axons of fully developed neurons pierce the optic neuropiles and leave and enter on the neuropile side. As a result, there is no chiasma in the non-Malacostracan groups.The Malacostraca have an extra neuropile, the medulla interna, derived from the medulla terminalis. Chiasmata occur between the lamina ganglionaris and the medulla externa, and between the medulla externa and the medulla interna. This difference from the non-Malacostracans depends on the course of the fibres. Those coming from the lamina ganglionaris leave the lamina on the neuropile side and enter medulla externa between the cell bodies in the perikaryon layer of the medulla externa neurons and the neuropile of the medulla. The fibres from the medulla externa to the lamina come from T-shaped neurons and emanate from the perikaryon layer side, entering the lamina on its neuropile side. The fibre relations between the medulla externa and the medulla interna are similar. Thus in both cases, chiasmata are present from the beginning, but they become obvious when the medulla externa rotates through part of a circle.The directed growth of the optic neuropiles and the course of the fibre connexions are consequently crucial to the understanding of the topographic relations between the neuropiles. A pattern with short neurons connecting neighbouring optic neuropiles and long neurons connecting the medulla externa with the central nervous system is common to all crustaceans.

Localization of monoaminergic neurons in the central nervous system of Astacus astacus Linné (Crustacea)

SummaryThe cellular localization of biogenic monoamines in crustaceans was studied by means of a highly specific and sensitive fluorescence method devised by Falck and Hillarp. It was found that neurons displaying specific fluorescence in the central nervous system were confined to the protocerebrum, the medulla externa and interna and the ventral nerve cord. The method allows a distinction between the fluorophores of 5-hydroxytryptamine (and 5-hydroxytryptophan), which emit the yellow light, and the fluorophores deriving from the catecholamines (and DOPA), which emit the green light. Green-fluorescent neurons occurred abundantly in the aforementioned parts of the central nervous system while yellow-fluorescent neurons were sparsely present in the same parts.

CENTRAL NERVOUS SYSTEM OF HUTCHINSONIELLA MACRACANTHA (CEPHALOCARIDA)

The central nervous system of the cephalocarid Hutchinsoniella macracantha is well developed, although missing several structures which are characteristic of the general crustacean plan. There are no signs of eyes either in the adult or in the larva. The organ of Bellonci, central body, protocerebral bridge, and paracentral lobes are absent. The mushroom bodies occur in the central nervous system in a form different from that found in malacostracan crustaceans and are unexpectedly well developed. They are connected to the olfactory lobes, which in this species are displaced ventrally into the clypeus (anterior part of the so-called labrum), extremely large, and of hitherto unseen construction. The central nervous system of Hutchinsoniella does not conform to a paradigm of overall primitiveness and must have evolved separately in the cephalocarid line for a long period.

Classification of amphipod compound eyes- the fine structure of the ommatidial units (Crustacea, Amphipoda)

SummaryThe ultrastructure of the compound eyes of 13 amphipod species has been investigated. An amphipod type of compound eye can be characterized by the constellation and consistency of a number of morphological features, most of which are also found in other compound eyes. The amphipod eye falls into four sub-categories (types). The ampeliscid type has a tripartite aberrant lens eye; the lysianassid type has a reduced or no dioptric apparatus and a hypertrophied rhabdom; the hyperid type possesses a large number of ommatidial units with long crystalline cones and dark instead of reflecting accessory pigment; and finally, the gammarid type can be interpreted as a generalized amphipod type. The lysianassid type is adapted to low light intensities and demonstrates convergent development with the compound eyes of other deep-sea crustaceans. The ampeliscid type is more similar to the gammarid type. The type characterization of the amphipod compound eye might well serve as a basis and incentive for functional studies also revealing adaptational mechanisms.

Distribution of monoaminergic neurons in the nervous system of non-malacostracan crustaceans

SummaryA comparative investigation of the distribution of monoaminergic neurons in non-malacostracan crustaceans was performed with the histochemical fluorescence method of Falck-Hillarp.Two fluorophores were found: the more widespread of the two emits a green fluorescence; and the more sparsely distributed emits a yellow to brown-yellow fluorescence.Specific green fluorescent areas were shown to exist in the protocerebrum. The central body and the optic ganglia of the compound eye (where present) are always fluorescent. Moreover, the centre of the nauplius eye may have a green fluorophore, as in ostracods, and a neuropile area, here called the frontal area. These neuropile centres are known from ordinary histological studies of the nervous system. In addition, there are specific monoaminergic centres, such as the so-called dorsal area of phyllopods and anostracans as well as the copepod specific areas. Specific monoaminergic areas appear in the deutocerebrum and the suboesophageal ganglion where they are particularly well developed.Presumed sensory neurons in the cavity receptor organ of Artemia salina are shown to be monoaminergic. Monoaminergic sensory neurons have not been described previously in Arthropods.Presumed motor innervation of hind-gut and trunk muscles is also found, and it is concluded that in crustaceans neurons of every type (sensory, internuncial, motor) may be monoaminergic.