Isolation and Identification of Multiple Neuropeptides of the Allatostatin Superfamily in the Shore Crab Carcinus Maenas

Abstract

20 neuropeptides belonging to the allatostatin superfamily were isolated from extracts of cerebral and thoracic ganglia of the shore crab Carcinus maenas. They were purified by HPLC, monitored by radioimmunoassay and identified by mass spectrometry and amino acid sequencing. The allatostatins are characterised by a common C‐terminal pentapeptide sequence ‐YXFGL‐NH2. Previously such peptides have only been reported from insects. In insects the variable post‐tyrosyl residue is restricted to Ala, Asn, Asp, Gly or Ser. In C. maenas, however, there are only two types; thirteen of the peptides having a post‐tyrosyl Ala and the other seven, a post‐tyrosyl Ser. The crab peptides include the shortest allatostatins so far identified (YAFGL‐NH2 and YSFGL‐NH2) as well as the longest, a 27‐residue peptide. The total of 20 peptides exceeds the highest number of allatostatins found in any of the insects investigated so far (14 in Periplaneta americana). It is of interest that, despite their clear homology, none of the peptides of C. maenas is identical to any of the more than 50 known insect allatostatins. The crab allatostatins show evidence of gene duplication and mutation that has resulted in several sub‐groups with close structural similarities. For example, there are four heptapeptides with the common C‐terminus ‐PYAFGL‐NH2 that differ only at the N‐terminal residue, which is either Glu, Asp, Asn or Ser. Other motifs, variously extended at the N‐terminus, include ‐GPY(A/S)FGL‐NH2 (three peptides), ‐DMY(A/S)FGL‐NH2 (three peptides), and ‐GQY(A/S)FGL‐NH2 (two peptides). Unique among the allatostatin superfamily, one of the crab peptides has a Tyr for Phe substitution at position three from the C‐terminus (GGPYSYGL‐NH2). Immunocytochemistry has provided clues to the functions of the allatostatins in crustaceans by showing their widespread presence in the central and stomatogastric nervous systems.

Neuromodulation of Spike-Timing Precision in Sensory Neurons

“…CBCTO afferents, unlike GPR2 neurons, can easily be studied intracellularly (DiCaprio, 2003;Gamble and DiCaprio, 2003). As in C. borealis, peptides belonging to the allatostatin superfamily have also been found in the CNS of C. maenas (Duve et al, 1997). Figure 3A shows a 100 ms segment of intracellular recording from a single CBCTO afferent in control saline and in 10 Ϫ6 M AST in response to a single cycle of repeated stimulation using a 5 s duration 140 Hz bandwidth white noise stimulus, along with raster plots of the last 60 stimulus trials and associated PSTHs.…”

Identification of SYWKQCAFNAVSCFamide: a broadly conserved crustacean C-type allatostatin-like peptide with both neuromodulatory and cardioactive properties

“…cockroaches, crickets and termites (Stay and Tobe, 2007). A-type peptides have also been found in a number of crustaceans (Duve et al, 1997;Dircksen et al, 1999;Duve et al, 2002;Huybrechts et al, 2003;Fu et al, 2005;Yasuda-Kamatani and Yasuda, 2006;Yin et al, 2006;Christie et al, 2008a;Ma et al, 2008;Gard et al, 2009;Ma et al, 2009), where they have been shown to function as locally released and/or hormonally delivered neuro/myomodulators (Skiebe and Schneider, 1994;Jorge-Rivera and Marder, 1997;Jorge-Rivera et al, 1998;Dircksen et al, 1999;Kreissl et al, 1999;Birmingham et al, 2003;Billimoria et al, 2006;Cruz-Bermúdez and Marder, 2007). Molecular, biochemical and mass spectral analyses have shown that multiple isoforms of A-type peptides are common in both insect and crustacean species, with multiple peptides encoded by the known arthropod A-AST prepro-hormones (e.g.…”

“…Molecular, biochemical and mass spectral analyses have shown that multiple isoforms of A-type peptides are common in both insect and crustacean species, with multiple peptides encoded by the known arthropod A-AST prepro-hormones (e.g. Duve et al, 1997;Dircksen et al, 1999;Lenz et al, 2000;Meyering-Vos et al, 2001;Duve et al, 2002;Huybrechts et al, 2003;Abdel-Latief et al, 2004;Fu et al, 2005;Yasuda-Kamatani and Yasuda, 2006;Yin et al, 2006;Bowser and Tobe, 2007;Christie et al, 2008a;Ma et al, 2008;Gard et al, 2009;Ma et al, 2009).…”

Circadian clocks in crustaceans: identified neuronal and cellular systems

“…However, even the previously suggested and reasonably analysed small neuropeptide nature of NDH (279) was later totally questioned (280). Nonetheless, it would be interesting to examine whether or not NDH is similar or in fact also part of a large family of proven myoinhibitory and neuroinhibitory allatostatin-A-type neuropeptides in crayfish O. limosus (Orcostatins; 281) that occur identically or in many isoforms in several other crustaceans (208,(282)(283)(284). Another type of NDH may belong to a family of small inhibitory opioid neuropeptides, the enkephalins, which are known to occur in several neurons and fibre networks of the eyestalk ganglia including the medulla terminalis of lobsters (285), crabs (286)(287)(288), and crayfish O. limosus (289), and are co-localised with MIH in the crab XOSG-neurons (288).…”