Comparative analysis of the jaw apparatus of three marine annelids using scanning electron microscopy: Microstructure and elemental composition.

Polychaeta are highly diversified invertebrates that inhabit marine, brackish or freshwater environments. They have acquired a unique range of adaptative features for securing food. However, the jaw apparatus may reveal not only defence and predation mechanisms, but also its relation to environmental chemistry. The present work compared the structure and chemical profile of the jaws of different estuarine Polychaeta: Nephtys hombergii (Nephtyidae), Hediste diversicolor (Nereididae) and Glycera alba (Glyceridae) using Scanning Electron Microscopy (SEM) and Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX). Analyses revealed that N. hombergii possesses a muscular jawless proboscis with terminal sensorial papillae for detecting prey, whereas the G. alba proboscis exhibits four delicately sharp jaws with perforations for venom delivery and H. diversicolor bears two blunt denticulated jaws to grasp a wide variety of food items. Melanin and metals like copper provide hardness to the slender jaws of Glycera, while, in the absence of heavier metallic elements, halogens contribute to H. diversicolor jaws robustness. The more specific chemistry of the jaws of glycerids is associated with its more refined venom injection, whereas Hediste is an opportunistic omnivore and Nepthys an agile forager. Altogether, the chemistry of jaws is an adaptive feature for feeding, locomotion and even resilience to complex and often adverse chemical profiles of estuaries.

An investigation into the toxicity of tissue extracts from two distinct marine Polychaeta.

The present study investigated the potential toxicity of venomous secretions of two polychaetes, Hediste diversicolor and Glycera alba (Annelida: Phyllodocida). Toxic activity of putative toxins, measured on mussel gills through the Comet assay, revealed higher effects caused by extracts from H. diversicolor skin and G. alba specialised, jawed proboscis, when compared to control. The results suggest that H. diversicolor secretes toxins via skin for protection against predators, contrarily to G. alba, who secretes toxins for predation.

The complete mitochondrial genome of Glycera chirori Izuka (Annelida: Polychaeta): an evidence of conservativeness between gene arrangement and phylogenesis in Glycera.

The complete mitochondrial genome of Glycera chirori Izuka (Annelida: Polychaeta) was presented, which is a circular molecule of 15,930 bp nucleotides. It encodes 37 genes, including 13 PCGs, 22 tRNAs, and two rRNAs. The length of non-coding regions is 1428 bp, and the longest one (1346 bp) is speculated as the control region, which is located between trnA and trnL2 and is longer than most species in Glycera. The complete mitogenome of G. chirori Izuka consists of 31.2% A, 23.6% C, 12.9% G, and 32.2% T, which has T vs. A skew (-0.02) and C vs. G skew (-0.29), respectively. Phylogenetic analysis indicates the classification status of G. chirori Izuka and the relationship with other species in Glycera, which is closer with Glycera unicornis and Glycera fallax (bootstrap = 100). By comparisons, the gene arrangement of G. chirori Izuka and other seven species in Glycera are identical and they also cluster together in phylogenetic tree with higher support rate, which indicates the conservativeness between gene arrangement and phylogenetic analysis in Glycera. In conclusion, the complete mitochondrial genome of G. chirori Izuka can provide supportive data for further molecular and evolutionary analysis of Glycera.

A Polychaete's powerful punch: venom gland transcriptomics of Glycera reveals a complex cocktail of toxin homologs.

Glycerids are marine annelids commonly known as bloodworms. Bloodworms have an eversible proboscis adorned with jaws connected to venom glands. Bloodworms prey on invertebrates, and it is known that the venom glands produce compounds that can induce toxic effects in animals. Yet, none of these putative toxins has been characterized on a molecular basis. Here we present the transcriptomic profiles of the venom glands of three species of bloodworm, Glycera dibranchiata, Glycera fallax and Glycera tridactyla, as well as the body tissue of G. tridactyla. The venom glands express a complex mixture of transcripts coding for putative toxin precursors. These transcripts represent 20 known toxin classes that have been convergently recruited into animal venoms, as well as transcripts potentially coding for Glycera-specific toxins. The toxins represent five functional categories: Pore-forming and membrane-disrupting toxins, neurotoxins, protease inhibitors, other enzymes, and CAP domain toxins. Many of the transcripts coding for putative Glycera toxins belong to classes that have been widely recruited into venoms, but some are homologs of toxins previously only known from the venoms of scorpaeniform fish and monotremes (stonustoxin-like toxin), turrid gastropods (turripeptide-like peptides), and sea anemones (gigantoxin I-like neurotoxin). This complex mixture of toxin homologs suggests that bloodworms employ venom while predating on macroscopic prey, casting doubt on the previously widespread opinion that G. dibranchiata is a detritivore. Our results further show that researchers should be aware that different assembly methods, as well as different methods of homology prediction, can influence the transcriptomic profiling of venom glands.

Glyceridae Grube 1850 (Annelida: Polychaeta) from Southern and Southeastern Brazil, including a new species of Glycera / Glyceridae Grube 1850 (Annelida: Polychaeta) da região sudeste e sul do Brasil, incluindo uma nova espécie de Glycera

This systematic study of the polychaete species of the family Glyceridae is part of a broader program to inventory and determine parameters for conservation and sustainable use of the marine biodiversity off the southeastern and southern coast of Brazil. The material studied was collected from intertidal sandy beaches, the inner continental shelf (<50 m depth) off the northern coast of the state of São Paulo, and the outer continental shelf and part of the continental slope (depths from 60 to 808 m) off the state of Rio de Janeiro south to Rio Grande do Sul (22º S - 34º 40' S). The descriptions of several species were improved, adding new and important taxonomic characters, mainly related to proboscideal papillae. A key for identification of the glycerid species from southeastern and southern Brazil is also provided. Eight species of Glyceridae were identified: Glycera americana Leidy 1855; Glycera brevicirris Grube 1870; Glycera dibranchiata Ehlers 1868; Glycera lapidum Quatrefages 1866; Glycera oxycephala Ehlers 1887; Glycera tesselata Grube 1863; Hemipodia californiensis (Hartman 1938); Hemipodia simplex (Grube 1857); and a previously unknown species of Glycera.

O estudo sistemático das espécies da família Glyceridae é parte de um amplo programa de inventariamento e determinação de parâmetros abióticos para conservação e uso sustentável da biodiversidade marinha ao largo da costa sudeste e sul do Brasil. O material estudado foi coletado desde a região entremarés de praias arenosas até a plataforma interna (<50 m prof.) na costa norte de São Paulo, e da plataforma externa ao talude superior (profundidades entre 60 e 808 m) desde a costa sul do Rio de Janeiro até a o sul do Rio Grande do Sul (22º S - 34º 40' S). As descrições de algumas espécies foram ampliadas, com a adição de novos e importantes caracteres taxonômicos, principalmente relacionados às papilas proboscidiais. Uma chave de identificação para as espécies de glicerídeos da região sudeste e sul do Brasil é fornecida. Oito espécies de Glyceridae foram identificadas: Glycera americana Leidy 1855; Glycera brevicirris Grube 1870; Glycera dibranchiata Ehlers 1868; Glycera lapidum Quatrefages 1866; Glycera oxycephala Ehlers 1887; Glycera tesselata Grube 1863; Hemipodia californiensis (Hartman 1938); Hemipodia simplex (Grube 1857); além de uma espécie previamente desconhecida de Glycera.