Lobsters, exoskeleton

Glucose molecules can link together into chains, with each ring tethered to the next by a bridging oxygen atom. In one form, this is cellulose, the stiff material that gives the stalks of plants and the trunks of trees their structural strength. Chitin, a variation on cellulose, is an even stiffen material that forms the exoskeletons of crustaceans such as crabs and lobsters. 

All indications are that we are only just beginning to see a few threads of the rich fabric of chemical signals that link lobsters to each other and to their environment. Exoskeleton, bladders, glands, and control of currents all indicate that these animals can be chemically quiet and release specific signals at critical times during aggression and courtship. Chemical signals appear to be used to remember individuals and to facilitate stable dominance hierarchies. 

Chitin is a polysaccharide similar to cellulose except that the OH at C-2 is replaced by an acetamido group (CH3CONH). Chitin is the main component of the hard external covering (exoskeleton) of crustaceans such as lobsters, crabs, and shrimp. Like cellulose, the processing of chitin into polymeric products is limited by its insolubility and decomposition without melting. The availability in huge quantities has encouraged many attempts to find commercial applications of chitin, but very few have been found to be economically feasible. 

Chitin is an abundant biopolymer, especially in Perth where the thriving Western rock lobster industry produces tonnes of waste, a good proportion of which is exoskeleton and rich in chitin. It has been our aim for some years to put this waste chitin to some good use and so, initially, we have set out to prepare epoxyalkyl glycosides based on W-acetyl-D-glucosamine and its oligomers, for example 60 and 61. It is hoped that molecules such as 60 and 61 will prove to be efficient inhibitors of chitinases, ubiquitous enzymes involved in many biological processes [42]. 

Barnacle, Elminius modestus-, pyrophosphate granules American lobster, Homarus americanus-, muscle Shrimps, unidentified Exoskeleton Muscle... 

The exoskeleton of the crab and other crustaceans is primarily composed of a substance called chitin. This is a giant molecule made up of fundamental units of N-acetyglucosamine strung together like links in a chain. Chitin is abundantly available, thanks to a crab and lobster industry dedicated to making it easier for us to consume their products by removing the... 

Chitin is a linear homopolysaccharide composed of Af-acetylglucosamine residues in /3 linkage (Fig. 7-18). The only chemical difference from cellulose is the replacement of the hydroxyl group at C-2 with an acety-lated amino group. Chitin forms extended fibers similar to those of cellulose, and like cellulose cannot be digested by vertebrates. Chitin is the principal component of the hard exoskeletons of nearly a million species of arthropods—insects, lobsters, and crabs, for example— and is probably the second most abundant polysaccharide, next to cellulose, in nature. 

These carotenoids have a limited distribution and occur as complexes, perhaps in Schiff base linkage, with proteins. Astaxanthin protein complexes with absorption maxima ranging from 410 nm to 625 nm or more provide the color to the lobster s exoskeleton.130132 Whereas most naturally occurring carotenoids have all-E double bonds, mono-Z isomers of canthaxanthin are found in the colored carotenopro-teins of the brine shrimp Artemesia.133... 

A radiation-induced signal can be detected in the exoskeleton of Norway lobster (Nephrops norvegicus) (Stewart etal., 1992) and other species of prawn and shrimp (Morehouse and Desrosiers, 1993). In the case of Norway lobster, the signal in both irradiated and unirradiated cuticle is complex because of the presence of the six resonance peaks due to Mn2+. In the irradiated samples there is an additional free radical peak in the centre of the Mn2+ signal at 349.5 mT (Figure 6). This signal is more easily seen when the... 

The shape of the radiation-induced signal was similar in different components of the exoskeleton of Norway lobster but the intensity of the peak varied (Stewart etal., 1993a). Consequently, the part of the cuticle used for EPR analysis will not affect identification of irradiation treatment but could influence the estimation of dose in samples of unknown processing history. 

Stewart, E.M., Stevenson, M.H and Gray, R. (1993a) The effect of irradiation dose and storage time on the ESR signal in the cuticle of different components of the exoskeleton of Norway lobster (Nephrops norvegicus) Appl. Radiat. Isot. 4, 433. 

Chitin is a polysaccharide constituted of N -acctylglucosamine, which forms a hard, semitransparent biomaterial found throughout the natural world. Chitin is the main component of the exoskeletons of crabs, lobsters and shrimps. Chitin is also found also in insects (e.g. ants, beetles and butterflies), and cephalopods (e.g. squids and octopuses) and even in fungi. Nevertheless, the industrial source of chitin is mainly crustaceans. 

The exoskeletons of shellfish such as crabs and lobsters as well as many insects contain a high concentration of chitin, which is very similar to cellulose (b 1,4-glycoside linkages), except that instead of an OH group at carbon-2, chitin has a substituted amine group (an amide) ... 

The Crustacea is the second largest group within the Arthropods. This diverse group includes lobsters, crabs, shrimp, sow bugs, barnacles, and many other forms. Over 38,000 species of Crustacea are known and there are probably many more yet to be discovered. Most Crustacea have a hard chitinous exoskeleton, three body segments, two pairs of antennae, and gills for breathing. Most... 

In museum collections, most invertebrates will be encountered as natural history specimens, which are divided into dry and wet-preserved. Those animals having a shell or tough exoskeleton, like starfish, shelled mollusks, and lobsters, may be dried after death. The tissue may be removed, but it is often left inside the shell or carapace to shrivel and dry. Wet-preserved specimens are usually fixed in a solution of formalin or some other preservative to prevent the tissues from deteriorating quickly after death. After a brief period, the specimen is usually removed from the toxic fixing solution, rinsed, and placed in a storage solution of 70% ethanol (alcohol) mixed with water. 

Chitin is isolated from the exoskeletons of crustaceans (e.g., crabs, lobsters, crayfish, shrimp, krill, barnacles), molluscs or invertebrate animals (e.g., squid, octopus, cuttlefish, nautilus, chitons, clams, oysters, scallops. 

Chitin is a structural carbohydrate that makes up the protective exoskeleton of arthropods such as beetles and lobsters. Chitin is one of the most abundant natural polymers on Earth due to the enormous number of Insects on our planet. The monomer In chitin Is similar to glucose, but It has a side chain containing an amide group attached to one carbon in the ring. 

This nitrogen-containing polysaccharide makes up the shells of lobsters, crabs, and the exoskeletons of insects. Draw a portion of a chitin polymer consisting of four monomers. 

Reflect and Apply Why is the polysaccharide chitin a suitable material for the exoskeleton of invertebrates such as lobsters What other sort of material can play a similar role ... 

Chitin is a homopolymer of AT-acetyl-D-glucosamine residues and is a major structural component in the exoskeletons of crustaceans, mollusks, arthropods, and the cell walls of numerous fungi and algae. Owing to its widespread presence in both terrestrial and aquatic organisms, chitin is second only to cellulose as the most abundant biopolymer on the Earth (Shahidi and Abuzaytoun, 2005). On a dry weight basis, shrimp, crab, lobster, prawn, and crayfish have been reported to contain between 14% and 35% chitin, while deproteinized dry shell waste of Antarctic krill contains approximately 40% crude chitin (Haard et al, 1994). Crustaceans are the primary sources of chitin used in industry. Chitin can be extracted from shellfish and crustacean waste by mixing with a dilute add to induce demineralization, followed by a deproteini-zation step in a hot alkaline solution (Synowiecki and Al-Khateeb, 2003). 

It is a substance found naturally in the shells of crustaceans, such as crab, shrimp, and lobster. It is also found in the exoskeleton of marine zooplankton, such as coral and jellyfish. Insects also have chitin in their wings. Examples would be butterflies and ladybugs. The cell walls of mushroom and other fungi contain this also. This substance is used in food, cosmetics, and biomedicine. It has been found to be an antibacterial, antifungal, and antiviral and used for wound dressings, sutures, cataract surgery, and periodontal disease treatment. Its many sources and uses make it a fascinating material. 

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