Crustacean hyperglycaemic hormone in the nervous system of the primitive crustacean species Daphnia magna and Artemia salina (Crustacea: Branchiopoda)

Abstract

Crustacean hyperglycaemic hormone-immunoreactive neuronal systems are detected in the central and peripheral nervous systems of two entomostracan crustaceans, Daphnia magna and Artemia salina, by immunocytochemistry using specific antisera against crustacean hyperglycaemic hormones of the decapod crustaceans Orconectes limosus and Carcinus maenas. In D. magna, four small putative interneurones are detected in the brain. In the thorax, ten bipolar peripheral neurones are stained by both antisera. They are obviously segmental homologues with centrally projecting axons that form interdigitating varicose fibres and terminals in putative neurohaemal areas next to the surface of the anterior part of the thoracic ganglia. Similar immunopositive neurones occur both in the central and peripheral nervous systems of A. salina. A total of five groups of neurones occur in the protocerebrum, the deutocerebrum and the mandibular ganglion. Some of the protocerebral neurones are bipolar and project to the dorsal frontal organ. A single pair of peripheral multipolar neurones in the maxillary segment projects centrally into the ventral nerve cord and innervates unidentified somatic muscles and tissues in the maxillary and the first appendage segments. None of the brain neurones in both species show similarities to decapod X-organ sinus gland neurosecretory neurones. Chromatography of brain extracts of D. magna combined with immunodot blotting revealed two strongly immunoreactive fractions at retention times close to that of the crustacean hyperglycaemic hormone of crayfish. Moreover, preabsorption controls suggest that the cross-reacting peptides of D. magna and A. salina are structurally closely related to those of decapods.

Crustacean hyperglycaemic hormone (CHH)-like peptides and CHH-precursor-related peptides from pericardial organ neurosecretory cells in the shore crab, Carcinus maenas, are putatively spliced and modified products of multiple genes

“…The cells are considered the origin of the novel PO-CHH, which is obviously released from the observed terminals at the surface of the POs, as confirmed by our release experiments. These cells are similar to anti-CHH immunopositive peripheral cells in comparable neurohaemal release sites, as described recently in Daphnia magna, Artemia salina, Locusta migratoria, Homarus gammarus and H. americanus [18,20,37,38], suggesting similar if not homologous cell types in different arthropod groups. Forms and distributions of varicosities and release terminals of these cells which occur over almost all the trunks and bars of the crab POs resemble those of previously described neurons containing cardioactive peptides, such as proctolin, crustacean cardioactive peptide, FMRFamide-related and allatostatin-related peptides, all of which originate in the thoracic ganglia (see [39,40], and H. Dircksen, unpublished work).…”

Pigment-dispersing hormone in Daphnia interneurons, one type homologous to insect clock neurons displaying circadian rhythmicity

“…This situation is similar in the CNS of balanid and copepod crustaceans, in which also only PDH-ir interneurons occur [65,66]. Interestingly, other cladoceran peptidergic neurons containing CHH, CCAP, and other peptides also occur only as interneurons in the CNS [36][37][38]. In decapod and isopod crustaceans, PDH-ir neurons also occur as interneurons involved, e.g., in visual information processing [5][6][7][8][9][10].…”

“…Nonetheless, little is known about the endocrine system of Daphnia except for sites of presumed neurosecretion, as detected earlier by histological methods [32][33][34]. However, neurohormones similar to decapod crustacean hyperglycemic hormones (CHH [35]) and crustacean cardioactive peptide (CCAP), known in many decapods for their important roles in controlling metabolism and growth by moulting, have been localized in D. magna [36][37][38][39], and ESTs from D. pulex [25] predict the presence of even more decapod-like hormones. CHH neurons in D. magna and Artemia salina do not occur in typical decapod-like X-organ-sinus gland (XOSG) neurosecretory pathways.…”

“…Instead, merely CHH-ir interneurons are seen in similar brain positions. The only prominent CHH-ir neurosecretory cells are of peripheral origin projecting to dorsal putative neurohemal areas in the thoracic VNC [37].…”

A new look at an old visual system: structure and development of the compound eyes and optic ganglia of the brine shrimp artemia salina linnaeus, 1758 (branchiopoda, anostraca)

“…The localization of neurotransmitters and neurohormones in the central nervous system has been studied histochemically (Elofsson and Klemm, 1971;Aramant and Elofsson, 1976) and immunohistochemically (Zhang et al, 1997;Harzsch and Waloszek, 2001a;Harzsch and Glötzner, 2002). Furthermore, data on the structure of the adult compound eyes (Elofsson and Odselius, 1975) and optic neuropils (Hentschel, 1962;Elofsson and Dahl, 1970;Nässel et al, 1978;Elofsson and Hagberg, 1986) at the cellular level are available.…”