Pigments ofChaetopterus variopedatus(polychaeta)

Do microplastics influence the long-term effects of ciprofloxacin on the polychaete Hediste diversicolor? An integrated behavioral and biochemical approach

Ciprofloxacin (CPX), the most commonly used fluoroquinolone antibiotic, and microplastics (MPs) are two classes of emerging contaminants with severe adverse impacts on aquatic organisms. Previous studies suggest that both CPX and MPs induce deleterious changes in exposed aquatic biota, but the characterization of a chronic and combined ecotoxicological response is not well known, especially in organisms from estuarine ecosystems. Thus, in this study, we investigated the behavioral and biochemical effects of environmentally relevant levels of CPX alone and in combination with polyethylene terephthalate (PET) microplastics over 28 days of exposure, using the polychaete Hediste diversicolor as a model. In addition to behavioral parameters, different biochemical endpoints were also evaluated, namely the levels of metabolic enzymes of phase I (7-ethoxy-resorufin-O-deethylase, EROD), and phase II (glutathione-S-transferase, GSTs), antioxidant defense (catalase, CAT; glutathione peroxidase, GPx; superoxide dismutase, SOD), oxidative damage (lipid peroxidation, by means of levels of thiobarbituric acid reactive substances [TBARS]) and acetylcholinesterase (AChE). Chronic exposure to ciprofloxacin caused a decrease in burrowing time and a significant increase in SOD activity. In animals exposed to the combination of CPX and PET MPs, effects on behavioral traits were also observed, with higher concentrations of MPs leading to a marked delay in the animals' burrowing time. In addition, these animals showed changes in their antioxidant defenses, namely, a significant increase in SOD activity, while GPx activity was severely compromised. For none of the experimental groups, significant alterations were observed in the metabolic enzymes, TBARS or AChE. These findings provide the first insights into the responses of H. diversicolor when exposed to the combination of CPX and PET MPs, highlighting that, although the here studied conditions, there was no evidence of oxidative damage or neurotoxicity, these organisms are not risk-free in co-exposure scenarios, even at low environmental relevant concentrations.

Endogenous Fluorescent Proteins in the Mucus of an Intertidal Polychaeta: Clues for Biotechnology

The vast ocean holds many unexplored organisms with unique adaptive features that enable them to thrive in their environment. The secretion of fluorescent proteins is one of them, with reports on the presence of such compounds in marine annelids being scarce. The intertidal Eulalia sp. is an example. The worm secretes copious amounts of mucus, that when purified and concentrated extracts, yield strong fluorescence under UV light. Emission has two main maxima, at 400 nm and at 500 nm, with the latter responsible for the blue–greenish fluorescence. Combining proteomics and transcriptomics techniques, we identified ubiquitin, peroxiredoxin, and 14-3-3 protein as key elements in the mucus. Fluorescence was found to be mainly modulated by redox status and pH, being consistently upheld in extracts prepared in Tris-HCl buffer with reducing agent at pH 7 and excited at 330 nm. One of the proteins associated with the fluorescent signal was localized in secretory cells in the pharynx. The results indicate that the secretion of fluorescent proteinaceous complexes can be an important defense against UV for this dweller. Additionally, the internalization of fluorescent complexes by ovarian cancer cells and modulation of fluorescence of redox status bears important considerations for biotechnological application of mucus components as markers.

Chaetopterus variopedatus Bioluminescence: A Review of Light Emission within a Species Complex

Chaetopterus variopedatus has been studied for over a century in terms of its physiology, ecology and life history. One focus of research is on its intrinsic bioluminescent emissions, which can be observed as a blue light emitted from the extremities of individual body segments, or as a secreted mucus. Even though research shows that C. variopedatus is a species complex miscategorized as a single species, all of the variants of this polychaete produce light, which has been investigated in terms of both physiology and biochemistry. Despite decades of study, there are still many questions about the luminescence reaction, and, as of yet, no clear function for light emission exists. This review summarizes the current knowledge on C. variopedatus luminescence in addition to briefly describing its morphology, life cycle and ecology. Possible functions for luminescence were discussed using observations of specimens found in Brazil, along with a comparison of previous studies of other luminescent organisms. Further study will provide a better understanding of how and why C. variopedatus produces luminescence, and purifying the protein and luciferin involved could lead to new bioanalytical applications, as this reaction is unique among all known luminescent systems.

The complexity of porphyrin-like pigments in a marine annelid sheds new light on haem metabolism in aquatic invertebrates

True green pigments in the animal kingdom are scarce and are almost invariably porphyrinoids. Endogenous porphyrins resulting from the breakdown of haem are usually known as “bile pigments”. The pigmentation of intertidal Polychaeta has long gained attention due to its variety and vivid patterning that often seems incompatible with camouflage, as it occurs with Eulalia viridis, one of the few truly green Polychaeta. The present study combined UV and bright-field microscopy with HPLC to address the presence and distribution of pigments in several organs. The results showed two major types of porphyrin-like pigments, yellowish and greenish in colour, that are chiefly stored as intraplasmatic granules. Whereas the proboscis holds yellow pigments, the skin harbours both types in highly specialised cells. In their turn, oocytes and intestine have mostly green pigments. Despite some inter-individual variation, the pigments tend to be stable after prolonged storage at −20 °C, which has important implications for future studies. The results show that, in a foraging predator of the intertidal where melanins are circumscribed to lining the nervous system, porphyrinoid pigments have a key role in protection against UV light, in sensing and even as chemical defence against foulants and predators, which represents a remarkable adaptive feature.

The hidden biotechnological potential of marine invertebrates: The Polychaeta case study

Marine biotechnology is under the spotlight, as researchers and industrialists become aware that bioprospecting through the oceans' vast biodiversity can replace the painstaking process of designing synthetic compounds. Millions of years of Natural Selection provided an almost inexhaustible source of marine products that can interfere with specific bioprocesses while being cost-effective, safer and more environmentally friendly. Still, the number of commercial applications of marine compounds, especially from eumetazoans, can seem disappointing. In most part, this results from the challenges of dealing with an immense biodiversity and with poorly known organisms with uncanny physiology. Consequently, shifting the current perspective from descriptive science to actually proposing applications can be a major incentive to industry. With this in mind, the present review focuses on one of the least studied but most representative group of marine animals: the Polychaeta annelids. Occupying nearly every marine habitat, from the deep sea to the intertidal, they can offer a wide array of natural products that are just beginning to be understood, showing properties compatible with anaesthetics, fluorescent probes, and even antibiotics and pesticides, for instance. Altogether, they are a showcase for the ocean's real biotechnological deterrent, albeit our still wispy knowledge on this vast and ancient environment.

Absolute Configuration and Body Part Distribution of the Alkaloid 6-epi-Monanchorin from the Marine Polychaete Chaetopterus variopedatus

As a result of the first study on secondary metabolites from the cosmopolitan bioluminescent marine tube polychaete Chaetopterus variopedatus, a new bicyclic guanidine alkaloid, 6- epi-monanchorin (1), along with the previously known monanchorin (2) were isolated. The structure of 1 was elucidated by spectroscopic and chemical methods, including a cleavage of the C1–O7 bond to obtain a secondary alcohol (3), which was used to determine the absolute configurations by Mosher's method. It was found that 1 and 2 were mainly accumulated in a secreted mucus special organ of the worm (food net), where green and blue-green microalgae were detected. A biosynthetic pathway to 6- epi-monanchorin and monanchorin from dietary polyenic fatty acid precursors was proposed.

A study on the digestive physiology of a marine polychaete (Eulalia viridis) through microanatomical changes of epithelia during the digestive cycle

As for many invertebrates, the gut of marine polychaete species has key physiological functions. However, studies integrating microanatomical descriptions with physiological processes are scarce. The present investigates histological, histochemical and cytological changes in the alimentary canal during the digestive cycle of the marine annelid Eulalia viridis, a species that combines opportunist scavenging, predation and cannibalistic behavior. The gut is comprised of an eversible pharynx, esophagus, intestine and rectum. Three main phases of digestion were identified, namely, resting/secretory, absorptive and excretory. The intestinal epithelium is complex and exhibited the most significant changes regarding intracellular digestion, excretion and storage. Conversely, the pharynx and esophagus were chiefly important for enzyme secretion. The results also indicate the existence of two distinct types of secretory cells in the intestine, with likely distinct physiological roles. Some similarities have been found between the intestinal epithelia and the molluscan (especially cephalopod) digestive gland, as, for instance, the shedding of apical corpuscles by digestive cells at posterior stages of digestion. The findings indicate that the digestive process in this worm is complex and related to the many physiological roles that cells need to play in the presence of reduced organ differentiation.

Trace and major elements distribution and transfer within a benthic system: polychaete Chaetopterus variopedatus, commensal crab Polyonyx gibbesi, worm tube, and sediments

Samples of the polychaete Chaetopterus variopedatus, worm tubes, commensal crab Polyonyx gibbesi and sediments were collected in eight sites in Todos os Santos Bay, Brazil, in order to evaluate the potential use of the polychaetes and crabs as biomonitors and to assess the relationships and accumulation of trace and major elements in different benthic compartments. Trace and major elements were determined by ICP OES. Organic carbon, total nitrogen and sulfur were determined by CNS elemental analyser. Tubes, crabs and polychaetes were important in the retention of trace and major elements. Metals that presented the highest accumulation in polychaetes (i.e. Mg>Al>Fe>Zn>Mn>Co>Cu>Ba>Cr) where the same for crabs (i.e. Mg>Al>Fe>Mn>Co>Zn>Cu>Ba>Cr). High concentrations of Al, Ba, Cr, Mn and Fe, from terrigenous sources, were observed in tubes, which presented accumulation factors up to 81.5 for Mn. Sedentary polychaetes are seen as good biomonitor alternatives for metal contamination studies, because they are one of the most abundant taxon in the benthic system, live in direct contact with sediments, are present in broad distributions and can also handle relatively high concentrations of metals ensuring chronic exposition. The possibility to work with not only the polychaete but also its tube offers advantages compared to bivalves that generally do not accumulate certain metals in very high levels.