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Chitosan is a biopolymer obtained from chitin, one of the most abundant and renewable materials on Earth. Chitin is a primary component of cell walls in fungi, the exoskeletons of arthropods such as crustaceans, e.g., crabs, lobsters and shrimps, and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians. The discovery of chitin in 1811 is attributed to Henri Braconnot while the history of chitosan dates back to 1859 with the work of Charles Rouget. The name of chitosan was, however, introduced in 1894 by Felix Hoppe-Seyler. Chitosan has attracted major scientific and industrial interests from the late 1970s due to its particular macromolecular structure, biocompatibility, biodegradability and other intrinsic functional properties. Chitosan and derivatives have practical applications in the food industry, agriculture, pharmacy, medicine, cosmetology, textile and paper industries, and in chemistry. In recent years, chitosan has also received much attention in dentistry, ophthalmology, biomedicine and bioimaging, hygiene and personal care, veterinary medicine, packaging industry, agrochemistry, aquaculture, functional textiles and cosmetotextiles, catalysis, chromatography, beverage industry, photography, wastewater treatment and sludge dewatering, and biotechnology. Nutraceuticals and cosmeceuticals are actually growing markets, and therapeutic and biomedical products should be the next markets in the development of chitosan. Chitosan is also the object of numerous fundamental studies. In this review, we highlight a selection of works on chitosan applications published over the past two decades.

Astaxanthin is the main natural C40 carotenoid used worldwide in the aquaculture industry. It normally occurs in red yeast Phaffia rhodozyma and green alga Haematococcus pluvialis and a variety of aquatic sea creatures, such as trout, salmon, and shrimp. Numerous biological functions reported its antioxidant and anti-inflammatory activities since astaxanthin possesses the highest oxygen radical absorbance capacity (ORAC) and is considered to be over 500 more times effective than vitamin E and other carotenoids such as lutein and lycopene. Thus, synthetic and natural sources of astaxanthin have a commanding influence on industry trends, causing a wave in the world nutraceutical market of the encapsulated product. In vitro and in vivo studies have associated astaxanthin’s unique molecular features with various health benefits, including immunomodulatory, photoprotective, and antioxidant properties, providing its chemotherapeutic potential for improving stress tolerance, disease resistance, growth performance, survival, and improved egg quality in farmed fish and crustaceans without exhibiting any cytotoxic effects. Moreover, the most evident effect is the pigmentation merit, where astaxanthin is supplemented in formulated diets to ameliorate the variegation of aquatic species and eventually product quality. Hence, carotenoid astaxanthin could be used as a curative supplement for farmed fish, since it is regarded as an ecologically friendly functional feed additive in the aquaculture industry. In this review, the currently available scientific literature regarding the most significant benefits of astaxanthin is discussed, with a particular focus on potential mechanisms of action responsible for its biological activities.HighlightsBeneficial use of astaxanthin as a feed supplement in cultured aquatic species.Screening of astaxanthin in pigmentation, growth and immunity enhancement, inflammatory response, and disease resistance of aquatic species.Astaxanthin prevents several diseases associated with oxidative stress in aquatic animals.

Viene segnalato il ritrovamento nel 2022 del partenopide Velolambrus expansus (Miers, 1879) nelle acque elleniche del mar Egeo. Questo granchio e considerato raro nel Mediterraneo e la distribuzione delle sue segnalazioni nel bacino viene aggiornata e brevemente discussa.

The main source of commercial chitosan is the extensive deacetylation of its parent polymer chitin. It is present in green algae, the cell walls or fungi and in the exoskeleton of crustaceans. A novel procedure for preparing chitosan from shrimp shells was developed. The procedure involves two 10-minutes bleaching steps with ethanol after the usual demineralization and deproteinization processes. Before deacetylation, chitin was immersed in 12.5 M NaOH, cooled down and kept frozen for 24 h. The obtained chitosan was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV, X-ray diffraction (XRD) and viscosimetry. Samples of white chitosan with acetylation degrees below 9 % were obtained, as determined by FTIR and UV-first derivative spectroscopy. The change in the morphology of samples was followed by SEM. The ash content of chitosan samples were all below 0.063 % . Chitosan was soluble in 1 % acetic acid with insoluble contents of 0.62 % or less. XRD patterns exhibited the characteristic peaks of chitosan centered at 10 and 20 degrees in 2 θ . The molecular weight of chitosan was between 2.3 and 2.8 × 10 5 g/mol. It is concluded that the procedure developed in the present work allowed obtaining chitosans with physical and chemical properties suitable for pharmaceutical applications.

Decapod crustaceans are ecologically and economically important invertebrates but are vulnerable to anthropogenic pressures and climate change. Understanding their spatial ecology is essential for their management and conservation, with telemetry emerging as a useful tool to quantify space-use and movements. Here, we synthesized the use of telemetry to study decapods among articles published from 1971 to 2019 (n = 102 studies), by taxonomic group of the study species, study location, objectives, number of animals tagged and their tag recovery rate, types (and trends) of telemetry used, and IUCN conservation status. These studies revealed insight into the behaviours and roles of decapods across habitats and geographic regions. The most common study species were crayfish and lobsters (41 %, Astacidea), and these studies also had the highest number of individuals tagged per study (mean = 149 individuals). Most studies (86 %) were conducted in the northern hemisphere. Acoustic tags were the most commonly used equipment (66 % of studies) and were first employed in 1971, followed by radio-telemetry (mid-1990s), passive integrated transponders (mid-2000s), and data storage tags (late 2000s). Almost half (48 %) of studies focused on species that had a conservation status of Least Concern, perhaps reflecting an applied science focus on animals of commercial interest rather than conservation importance. The positive allometric relationship between body length and movement rate (exponent = 0.86) demonstrates the type of broader ecological insight that combining these studies can provide. Tracking decapod movements will likely become increasingly important for managing fisheries, protecting sensitive species, and understanding invasion biology.

The Atlantic blue crab Callinectes sapidus (Decapoda, Portunidae) Rathbun, 1896 is native to the east coasts of North and South America and has recently expanded its distribution in the non-native range into the Gulf of Cadiz (SW Iberian Peninsula, Europe). Considering the impacts caused by this invasive species in numerous estuarine ecosystems and its generalist feeding behavior, this study aims to provide the first account of the Atlantic blue crab diet on the East Atlantic coast. We studied the species’ feeding habits using stomach content analyses to predict food web interactions and putative impacts. Samples were obtained in the Guadalquivir estuary (SW Spain, Europe), which was colonized in 2017. The main food items identified on their stomach were, fish (49.9%), mollusks (44.4%) and crabs (32.3%). They also consumed plant material (27.2%), and the sediment (32.3%) in their digestive tract was likely the result of secondary ingestion. The Atlantic blue crab exhibited the same omnivorous behavior as in the native area. There was no sexual variation in diet composition or feeding activity in general, but there was a seasonal variation in the diet composition of females. The decrease of the caramote prawn Penaeus kerathurus (Forskål 1775) observed in the Guadalquivir estuary since 2021 is likely not due to the Atlantic blue crab because they seldomly eat this prey. Overall, our study provides clear baseline information to expand the knowledge about the ecological roles of the Atlantic blue crab in non-native ecosystems.

Chitin is the second most abundant biopolymer consisting of N-acetylglucosamine units and is primarily derived from the shells of marine crustaceans and the cell walls of organisms (such as bacteria, fungi, and algae). Being a biopolymer, its materialistic properties, such as biodegradability, and biocompatibility, make it a suitable choice for biomedical applications. Similarly, its deacetylated derivative, chitosan, exhibits similar biocompatibility and biodegradability properties, making it a suitable support material for biomedical applications. Furthermore, it has intrinsic material properties such as antioxidant, antibacterial, and antitumor. Population studies have projected nearly 12 million cancer patients across the globe, where most will be suffering from solid tumors. One of the shortcomings of potent anticancer drugs is finding a suitable cellular delivery material or system. Therefore, identifying new drug carriers to achieve effective anticancer therapy is becoming essential. This paper focuses on the strategies implemented using chitin and chitosan biopolymers in drug delivery for cancer treatment.

In 1799, Hatchett decalcified shells of crabs, lobsters, prawns and crayfish with mineral acids, observing that they produced a moderate effervescence and in a short time were found to be soft and plastic of a yellowish color and like a cartilage, which retained the original figure. Although this is the first mention of calcified chitin in invertebrates, the discovery of chitin is usually attributed both to Braconnot in 1811 who discovered chitin from fungi, and to Odier in 1823 who obtained a hornlike material after treatment of cockchafer elytra with potassium hydroxide. Chitin was first named fongine by Braconnot and then chitine by Odier. Children revealed the nitrogenous nature of chitin in 1824. The history of chitosan, the main derivative of chitin, dates back to 1859 with the work of Rouget. The name of chitosan was, however, introduced in 1894 by Hoppe-Seyler. In 1876, Ledderhose hydrolyzed arthropod chitin and discovered glykosamin, the first derivative of chitin. This review describes the 220 years of the development of chitin. I have roughly divided the story into five periods: discovery from 1799 to 1894, a period of confusion and controversy from 1894 to 1930, exploration in 1930–1950, a period of doubt from 1950 to 1970, and finally the period of application from 1970. The different periods are illustrated by examples of published studies, in particular from outstanding scholars who have left their mark on the history of this polysaccharide. Although this historic review is not exhaustive, it highlights the work of researchers who have contributed to the development of our knowledge of chitin throughout the 220 years of its history.

Chitin and its derivative chitosan are popular constituents in wound-treatment technologies due to their nanoscale fibrous morphology and attractive biomedical properties that accelerate healing and reduce scarring. These abundant natural polymers found in arthropod exoskeletons and fungal cell walls affect almost every phase of the healing process, acting as hemostatic and antibacterial agents that also support cell proliferation and attachment. However, key differences exist in the structure, properties, processing, and associated polymers of fungal and arthropod chitin, affecting their respective application to wound treatment. High purity crustacean-derived chitin and chitosan have been widely investigated for wound-treatment applications, with research incorporating chemically modified chitosan derivatives and advanced nanocomposite dressings utilizing biocompatible additives, such as natural polysaccharides, mineral clays, and metal nanoparticles used to achieve excellent mechanical and biomedical properties. Conversely, fungi-derived chitin is covalently decorated with -glucan and has received less research interest despite its mass production potential, simple extraction process, variations in chitin and associated polymer content, and the established healing properties of fungal exopolysaccharides. This review investigates the proven biomedical properties of both fungal- and crustacean-derived chitin and chitosan, their healing mechanisms, and their potential to advance modern wound-treatment methods through further research and practical application.

The quantum of marine fish wastes produced by fish processing industries has necessitated to search new methods for its disposal. Hence, this study is focused on production and purification of halophilic organic solvent tolerant protease (HOSP) from marine Alcaligenes faecalis APCMST-MKW6 using marine shell wastes as substrate. The candidate bacterium was isolated from the marine sediment of Manakudi coast and identified as A. faecalis APCMST-MKW6. The purified protease showed 16.39-fold purity, 70.34 U/mg specific activity with 21.67 % yield. The molecular weight of the purified alkaline protease was 49 kDa. This purified protease registered maximum activity at pH 9 and it was stable between pH 8–9 after 1.30 h of incubation. The optimum temperature registered was 60 °C and it was stable between 50 and 60 °C even after 1.30 h of incubation. This enzyme also showed maximum activity at 20 % NaCl concentration. Further, manganese chloride, magnesium chloride, calcium chloride and barium chloride influenced this enzyme activity remarkably and it was also found to be enhanced by many of the tested surfactants and solvents. The candidate bacterium effectively deproteinized the shrimp shell waste compared to the other tested crustaceans shell wastes and also attained maximum antioxidant activity.