The Crustacean Neuropeptides of the CHH/MIH/GIH Family: Structures and Biological Activities

Circadian clocks in crustaceans: identified neuronal and cellular systems

“…The Xorgan somata are located at the anterior lateral cortex of the medulla terminalis proximal to the hemiellipsoid body, and the sinus gland, which is usually situated adjacent to the medial edge between the medullae externa and interna, is formed by axonal endings of XOSG and other neurons that abut upon lacunae around the large ophthalmic artery. From these neurohaemal XOSG terminals several identified neuropeptides are released into the haemolymph, such as red pigment concentrating hormone (RPCH), crustacean hyperglycaemic hormones (CHHs), moult-inhibiting hormone (MIH), vitellogenesis/gonad-inhibiting hormone (VIH/GIH), and mandibular organ-inhibiting hormone (MOIH) (127)(128)(129)(130)(131)(132)(133). However, the sinus gland receives additional inputs from other regions of the eyestalk ganglia outside the XOSG and even from the brain (134)(135)(136).…”

“…However, CHHs are distinguished when looking at the simpler gene and precursor structures of the latter subfamily peptides, which e.g. lack so-called precursor-related peptides (131,158,159). CHH subfamily peptides usually consist of 72-73 amino acids (aa), show a sequence similarity exceeding 55% between species, and have at least eight different established physiological functions (131,(160)(161)(162).…”

Moult cycle‐related changes in biological activity of moult‐inhibiting hormone (MIH) and crustacean hyperglycaemic hormone (CHH) in the crab, Carcinus maenas

“…Whilst the primary structures of over 50 of these peptides have been described, using a combination of microsequencing and cDNA cloning approaches [1,2], we still know remarkably little regarding the physiologically relevant roles of these neurohormones. In many cases, several processes appear to be regulated by single hormones, as might be expected, given the centrally important roles of these hormones in regulatory mechanisms, particularly those related to moulting and reproduction.…”

Identification of Neuropeptides from the Sinus Gland of the Crayfish Orconectes limosus Using Nanoscale On-line Liquid Chromatography Tandem Mass Spectrometry

“…Studies in crustaceans have demonstrated the X-Organsinus gland neurosecretory system (XO-SG) 1 as a source of various neuropeptides (1,2). The most relevant progress has been achieved in structure elucidation of a novel family of large peptides from the sinus gland (SG), which includes, according to their first-discovered biological activities, crustacean hyperglycaemic (CHH), moult-inhibiting (MIH) and vitellogenesis/gonad-inhibiting (VIH/GIH) hormones (3,4). Two subfamilies may be distinguished at the preprohormone level, either containing an associated CHH precursor-related peptide sequence (CPRP), located between the signal peptide and the native hormone sequence, characteristic for the CHH subfamily, or without this CPRP sequence, as determined for the MIH/VIH/GIH subfamily.…”

“…CPRPs have also been identified in other invertebrate groups such as insects and nematodes (4,5). These neurohormones are classically considered as major physiological regulators involved in the control of carbohydrate metabolism and in various functions in development such as moult and reproduction (3,6,7). Additionally, the chromatophore-regulating hormones, like red pigmentconcentrating hormone (RPCH) and pigment-dispersing hormone (PDH), have been found in the XO-SG system of different crustacean species (8 -11).…”