Chitin nanofibers were prepared from dried crab shells by a simple grinding treatment in a never-dried state under an acidic condition after the removal of proteins and minerals. The obtained ...nanofibers were observed by FE-SEM and found to have a uniform width of approximately 10-20 nm and high aspect ratio; both these findings were similar to those for nanofibers from prawns. Furthermore, it was confirmed that the nanofibers were extracted from the natural chitin/protein/mineral composites of crab shell in their original state. That is, the N-acetyl group was not removed and the *a-chitin crystal structure was maintained, as confirmed by elemental analysis data, FT-IR spectra, and X-ray diffraction profiles.
High resolution synchrotron X-ray fiber diffraction data recorded from crab tendon chitin have been used to describe the crystal structure of *a-chitin. Crystal structures at 100 and 300 K have been ...solved using restrained crystallographic refinement against diffraction intensities measured from the fiber diffraction patterns. The unit cell contains two polymer chains in a 21 helix conformation and in the antiparallel orientation. The best agreement between predicated and observed X-ray diffraction intensities is obtained for a model that includes two distinctive conformations of C6-O6 hydroxymethl group. Those conformations are different from what is proposed in the generally accepted *a-chitin crystal structure (J. Mol. Biol. 1978, 120, 167-181). Based on refined positions of the O6 atoms, a network of hydrogen bonds involving O6 is proposed. This network of hydrogen bonds can explain the main features of the polarized FTIR spectra of *a-chitin and sheds some light on the origin of splitting of the amide I band observed on *a-chitin IR spectra.
Designer proteins deprived of its IgE-binding reactivity are being sought as a regimen for allergen-specific immunotherapy. Although shrimp tropomyosin (Met e 1) has long been identified as the major ...shellfish allergen, no immunotherapy is currently available. In this study, we aim at identifying the Met e 1 IgE epitopes for construction of hypoallergens and to determine the IgE inhibitory capacity of the hypoallergens. IgE-binding epitopes were defined by three online computational models, ELISA and dot-blot using sera from shrimp allergy patients. Based on the epitope data, two hypoallergenic derivatives were constructed by site-directed mutagenesis (MEM49) and epitope deletion (MED171). Nine regions on Met e 1 were defined as the major IgE-binding epitopes. Both hypoallergens MEM49 and MED171 showed marked reduction in their in vitro reactivity towards IgE from shrimp allergy patients and Met e 1-sensitized mice, as well as considerable decrease in induction of mast cell degranulation as demonstrated in passive cutaneous anaphylaxis assay. Both hypoallergens were able to induce Met e 1-recognizing IgG antibodies in mice, specifically IgG2a antibodies, that strongly inhibited IgE from shrimp allergy subjects and Met e 1-sensitized mice from binding to Met e 1. These results indicate that the two designer hypoallergenic molecules MEM49 and MED171 exhibit desirable preclinical characteristics, including marked reduction in IgE reactivity and allergenicity, as well as ability to induce blocking IgG antibodies. This approach therefore offers promises for development of immunotherapeutic regimen for shrimp tropomyosin allergy.
There is a debate on whether invertebrates possess an antiviral immunity similar to the interferon (IFN) system of vertebrates. The Vago gene from arthropods encodes a viral-activated secreted ...peptide that restricts virus infection through activating the JAK-STAT pathway and is considered to be a cytokine functionally similar to IFN. In this study, the first crustacean IFN regulatory factor (IRF)-like gene was identified in Pacific white shrimp, Litopenaeus vannamei. The L. vannamei IRF showed similar protein nature to mammalian IRFs and could be activated during virus infection. As a transcriptional regulatory factor, L. vannamei IRF could activate the IFN-stimulated response element (ISRE)-containing promoter to regulate the expression of mammalian type I IFNs and initiate an antiviral state in mammalian cells. More importantly, IRF could bind the 5'-untranslated region of L. vannamei Vago4 gene and activate its transcription, suggesting that shrimp Vago may be induced in a similar manner to that of IFNs and supporting the opinion that Vago might function as an IFN-like molecule in invertebrates. These suggested that shrimp might possess an IRF-Vago-JAK/STAT regulatory axis, which is similar to the IRF-IFN-JAK/STAT axis of vertebrates, indicating that invertebrates might possess an IFN system-like antiviral mechanism.
Over the past twenty years microplastic pollution has been recorded in all major marine habitats, and is now considered to be of high environmental concern. Correspondingly, the number of reports of ...microplastic ingestion by marine species is increasing. Despite this, there are still relatively few studies which address the uptake and retention of microplastic in wild populations. Langoustine, Nephrops norvegicus, sampled from the Clyde Sea Area, have previously been seen to contain large aggregations of microplastic fibres. The large proportion of contaminated individuals and size of the microplastic aggregations observed suggests that Nephrops are at high risk of microplastic ingestion. In this study the levels of ingested microplastic in populations of N. norvegicus from the Clyde Sea Area, North Minch and North Sea are examined. Animals in the near-shore, Clyde Sea population showed both a higher percentage of microplastic containing individuals and much greater weights of microplastic retained in the gut. N. norvegicus revealed that only a small percentage of individuals from the North Sea and Minch contained microplastic, predominantly single strands. An expanded sample from the Clyde Sea Area was examined to identify the factors influencing microplastic retention. This revealed that males, larger individuals, and animals that had recently moulted contained lower levels of microplastic. The presence of identified food items in the gut was not seen to correlate with microplastic loads. Observations of microplastic in the shed stomach lining of recently moulted individuals and the lack of aggregations in wild-caught individuals suggests that ecdysis is the primary route of microplastic loss by N. norvegicus. Therefore the large aggregations observed in wild-caught animals are believed to build up over extended periods as a result of the complex gut structure of N. norvegicus.
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•We examine the level of microplastic in three populations of Nephrops norvegicus.•Animals from the Clyde Sea Area showed a high incidence of large aggregations.•A small percentage of individuals the North Sea and Minch contained microplastic.•Males, newly moulted, and larger animals contained less microplastic.•We propose that ecdysis is the major route of microplastic loss by N. norvegicus.
Analysis of microplastic aggregation by wild Nephrops norvegicus from three populations determined that location and moult stage have the largest effect on aggregation.
A novel PCR-RFLP method was evaluated as a tool to assess the incidence of incorrect labelling of prawns and shrimps in commercial food products. The whole method can be performed in less than 8 h in ...only one day of work. PCR amplification with primers 16Scru4/16Scru3, targeted to the amplification of a ca. 530 bp region of 16S rRNA and tRNA super(Val) mitochondrial genes, was coupled to restriction analysis with AluI, TaqI or HinfI. Forty-one commercial food products were considered. The molecular method considered allowed the identification of up to 17 different prawn and shrimp species in all the processed products considered. Seven (28%) of the 25 food products declaring one or more species in their labels were incorrectly labelled. Authentication was successfully assessed in commercial peeled products subjected to industrial processing, in which none of the products displayed labelling at species level. Overall, incorrect labelling was detected in 10 (24.4%) of the 41 commercial products tested, while another 16 samples (39%) exhibited incomplete labelling. The molecular method evaluated in this study proved to be a rapid and easy-to-perform two-step analytical approach to achieve species identification of commercial whole specimens of frozen prawns and shrimps and in peeled processed products where such raw materials are included as added-value ingredients.
All of the three pictures and films can be used for the education of road safety. A: Its a set of pictures, which uses the contrastive method to highlight the importance of seat belts. The pictures ...first show a crab, whose pincers were lost in a fight for food with others. At the same time, a road traffic crash happens to a driver without wearing seatbelt, then the driver loses one leg. After 6 months, the crab has its reborn pincers. However, the driver doesn't. Finally, it is showed that please buckle up when driving if you don't have the regenerated ability. B&C: these two films both use the toys to simulate the scenes of road traffic accident because of drinking driving/speeding. There is no bloody scene. And they are much more friendly to children for education. Each film has one core message. B shows that about 50–60% road traffic crashes are related to drink-driving. C shows that reducing the average speed by 1 km/h results in a 4–5% decrease in fatal crash.
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