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    Two S-Iamide Peptides, AKSGFVRIamide and VSSFVRIamide, Isolated from an Annelid, Perinereis vancaurica
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    Abstract:
    Two peptides, H-Ala-Lys-Ser-Gly-Phe-Val-Arg-Ile-NH2 (AKSGFVRIamide), and H-Val-Ser-Ser-Phe-Val-Arg-Ile-NH2 (VSSFVRIamide) were isolated from a polychaete annelid, Perinereis vancaurica. Both the peptides evoked rhythmic contractions in the esophagus of Perinereis with a threshold as low as 10-10-10-9 M, suggesting that the peptides may be involved in the regulation of gut motility of the animal. The sequences of these peptides are very similar to those of other S-Iamide family peptides which have been previously isolated from an echiuroid worm and some molluses. In particular, the sequence of VSSFVRIamide is identical to that of an echiuroid S-Iamide peptide. All of the molluscan and echiuroid S-Iamide peptides, as well as the annelid peptides, were found to produce contractions in the esophagus of Perinereis. On the other hand, the annelid S-Iamide peptides, as well as the molluscan and echiuroid peptides, were found to inhibit or potentiate contractions elicited by electrical stimulation in echiuroid and molluscan muscles. S-Iamide peptides may be a typical neuropeptide family distributed interphyletically in the Protostomia.
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    Annelid
    Early annelid evolution is mostly known from 13 described species from Cambrian Burgess Shale-type Lagerstätten. We introduce a new exceptionally well-preserved polychaete, Ursactis comosa gen. et sp. nov., from the Burgess Shale (Wuliuan Stage). This small species (3–15 mm) is the most abundant Cambrian polychaete known to date. Most specimens come from Tokumm Creek, a new Burgess Shale locality in northern Kootenay National Park, British Columbia, Canada. Ursactis has a pair of large palps, thin peristomial neurochaetae and biramous parapodia bearing similarly sized capillary neurochaetae and notochaetae, except for segments six to nine, which also have longer notochaetae. The number of segments in this polychaete range between 8 and 10 with larger individuals having 10 segments. This number of segments in Ursactis is remarkably small compared with other polychaetes, including modern forms. Specimens with 10 segments show significant size variations, and the length of each segment increases with the body length, indicating that body growth was primarily achieved by increasing the size of existing segments rather than adding new ones. This contrasts with most modern polychaetes, which typically have a larger number of segments through additions of segments throughout life. The inferred growth pattern in Ursactis suggests that annelids had evolved control over segment addition by the mid-Cambrian.
    Annelid
    Lagerstätte
    Taphonomy
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    Zootaxa has been the leading journal on invertebrate systematics especially within Annelida. Our current estimates indicate annelids include approximately 20,200 valid species of polychaetes, oligochaetes, leeches, sipunculans and echiurans. We include herein the impact of Zootaxa on the description of new annelid species in the last two decades. Since 2001, there have been over 1,300 new annelid taxa published in about 630 papers. The majority of these are polychaetes (921 new species and 40 new genera) followed by oligochaetes (308 new species and 10 new genera) and leeches (21 new species). The numerous papers dealing with new polychaete species have provided us a clear picture on which polychaete families have had the most taxonomic effort and which authors and countries have been the most prolific of descriptions of new taxa. An estimated additional 10,000+ species remain to be described in the phylum, thus we urge annelid workers to continue their efforts and aid in training a new generation of taxonomists focused on this ecologically important group.
    Annelid
    Taxonomic rank
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