Distribution of C-type allatostatin (C-AST)-like immunoreactivity in the central nervous system of the copepod Calanus finmarchicus

Abstract

The C-type Allatostatins (C-ASTs) are a family of highly pleiotropic arthropod neuropeptides. In crustaceans, transcriptomic/mass spectral studies have identified C-ASTs in the nervous systems of many species; the cellular distributions of these peptides remain unknown. Here, the distribution of C-AST was mapped in the nervous system of the copepod Calanus finmarchicus, the major contributor to the North Atlantic's zooplanktonic biomass; C-AST-immunopositive neurons were identified in the protocerebrum, in several peripheral ganglia associated with feeding appendages, and in the ganglia controlling the swimming legs, with immunopositive axons present throughout the ventral nerve cord. In addition, axons innervating the dorsal longitudinal and ventral longitudinal muscles of the body wall of the metasome were labeled by the C-AST antibody. While the distribution of C-AST-like immunoreactivity was similar between sexes, several differences were noted, i.e. two pair of somata located at the deutocerebral/tritocerbral border in males and immunopositive fibers that surround the genital opening in females. To place the C-AST-like labeling into context with those of several previously mapped peptides, i.e. A-type allatostatin (A-AST) and tachykinin-related peptide (TRP), we conducted double-labeling studies; the C-AST-like immunopositive neurons appear distinct from those expressing either A-AST or TRP (and through extrapolation, pigment dispersing hormone). Collectively, our data represent the first mapping of C-AST in crustacean neural tissue, show that sex-specific differences in the distribution of C-AST exist in the C. finmarchicus CNS, and suggest that the peptide may be involved in the modulation of both feeding and postural control/locomotion.

Mass spectrometric elucidation of the neuropeptidome of a crustacean neuroendocrine organ

“…Figure 4 shows the localization of three major neuropeptide families in C. sapidus PO: AST-B, RYamide and FLPs, all of which are shown to be involved in feeding behavior of crustaceans based on previous reports [2, 5, 19, 42]. Several isoforms of the AST-B family display colocalization patterns in the PO, including VPNDWAHFRGSWamide ( m/z 1470.70), AGWSSMRGAWamide ( m/z 1107.52), and a novel isoform, SGDWSSLRGAWamide ( m/z 1220.58), with a high concentration in the posterior bar region, dorsal trunk and anterior bar region.…”

Crustacean neuroendocrine systems and their signaling agents

“…For over 40 years, immunohistochemisty has been the primary method used for mapping neurochemical distributions in crustaceans (e.g., Jaros and Keller 1979;Van Herp and Van Buggenum 1979;Hartline and Christie 2010;Sharp et al 2010;Wilson and Christie 2010). Via this method, numerous molecules, including peptides, amines, small molecule transmitters and diffusible gases (e.g., Christie et al 1995aChristie et al , 2003Christie et al , 2004aPulver and Marder 2002;Fu et al 2005b), have been identified and/or mapped in crustacean neuroendocrine organs.…”

Neuropeptide complexity in the crustacean central olfactory pathway: immunolocalization of A-type allatostatins and RFamide-like peptides in the brain of a terrestrial hermit crab

“…They are also present in the nervous system of a non-malacostracan crustacean, the copepod Calanus finmarchicus [42]. In the current study we set out to analyze the role of A-ASTs in the crustacean brain in more detail by analyzing their distribution in the terrestrial hermit crab Coenobita clypeatus (Anomura, Coenobitidae) focussing on its central olfactory pathway.…”