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.
The goal of this study was to investigate the effects of dietary supplementation with β-glucan and synbiotics (i.e., microencapsulated Bacillus subtilis and Pediococcus acidilactici) on immune gene ...expression and immune parameters of Pacific white shrimp (Litopenaeus vannamei) as well as modulation of immune parameters when shrimp were exposed to ammonia stress. Shrimp were fed one of four treatment diets basal diet (C), β-glucan-containing diet (β-glu), β-glucan plus B. subtilis-containing diet (β-glu+Bs), and β-glucan plus P. acidilactici-containing diet (β-glu+Pa) for 90days. The microencapsulated bacteria colonized in the proximal and central parts of the shrimp intestine. The β-glu diet increased expression of lipopolysaccharide and β-1,3-glucan-binding protein (LGBP), and the β-glu+Bs diet induced expression of the serine protease and prophenoloxidase genes. In addition, β-glu + Pa increased the LGBP transcription. However, the mRNA level of peroxinectin did not differ significantly among the experimental groups. Shrimp fed the β-glu and β-glu+Pa diets had higher superoxide dismutase activity (SOD) compared to shrimp fed the basal diet. In addition, the β-glu+Bs and β-glu+Pa diets increased phenoloxidase activity (PO). However, there were no significant differences in total hemocyte count (THC) and lysozyme activity among the treatment diets. Ammonia stress led to increased THC and decreased SOD activity, but it seemed to have no adverse effects on PO and lysozyme activity. Thus, both β-glucan and synbiotic supplementation had beneficial effects on several immune parameters, and the effect of dietary synbiotics was superior to that of β-glucan only for PO activity.
•Colonization of microencapsulation of probiotic shrimp intestine•Dietary β-glucan induced the transcription of lipopolysaccharide and β-1,3-glucan-binding protein.•Dietary β-glucan and Bacillus subtilis induced expression of serine protease and prophenoloxidase genes.•Dietary β-glucan and probiotic had beneficial effects on immune parameters.
The aim of this study is to describe current chemical use practices in the aquaculture sector of Bangladesh and to identify the factors that influence them. A survey on the use of chemical and ...biological products was conducted between November 2011 and June 2012 using structured questionnaires administered to operators of nine farm groups, including homestead ponds, carps, tilapias, koi fish, shrimps, shrimps and prawns, prawns, rice and fish, and pangas. Farm type and farm owner characteristics were used as independent variables to explain observed chemical use. Forty-six chemical and biological products (7 water and sediment treatment compounds, 13 disinfectants, 7 antibiotics, 7 pesticides, 8 fertilizers and 4 feed additives and probiotics) were reported to be applied in aquaculture. The use of disinfectants and antibiotics was found to be highest in intensive koi and pangas farms as compared to other farm groups, whereas the use of fertilizers was lowest in these farm groups. A higher percentage of prawn and shrimp/prawn farmers applied pesticides than other farm groups. A multivariate analysis showed that patterns of use of chemical and biological products were significantly different across aquaculture farm groups, with the largest number of chemical compounds used by the intensive koi farm group. The study shows that, despite rapid expansion of commercial aquaculture in Bangladesh, use of chemical and biological products is still relatively low compared to other aquaculture producing countries in Asia. However, despite this finding, the study identified a large number of compounds that are currently in use, and that require further regulation and evaluation regarding their potential environmental and human health impacts, as already done in most developed countries.
Chemical use practices in Bangladesh
Fifty-three lactic acid bacteria (LAB) strains were respectively isolated from commercial probiotics, and the intestinal tracts of shrimp (Fenneropenaeus chinensis) and fish (Acanthogobius hasta). ...The antibacterial and adhesive activities of these strains were examined, the results showed that Lactobacillus pentosus HC-2 (L. pentosus HC-2) and Enterococcus faecium NRW-2 (E. faecium NRW-2) had higher antibacterial and adhesive activity, respectively, the identification of strains was based on the 16S rRNA analysis. The aim of this study was to investigate and compare the effects of E. faecium NRW-2, L. pentosus HC-2 and the corresponding supernatant on the immune response and growth performance of shrimp (Litopenaeus vannamei). Real-time PCR was used to determine the expression levels of immune- and digestion-related genes in the midgut and hepatopancreas. Our results suggested that E. faecium NRW-2 had higher stimulation to all tested genes, except crustin and proPO in the midgut at two weeks and four weeks post-feeding, respectively, while L. pentosus HC-2 and its corresponding supernatant had higher induction of genes in the hepatopancreas. According to the challenge tests, all of the treatment groups had significantly higher survival rate than the control group. Moreover, the specific growth rates of shrimp fed with selected strains were higher than the control group; whereas that of the supernatant of the L. pentosus HC-2-containing group was lower than the control even though it was not significant. The present study indicates that the selected strains could be used as effective components in the shrimp diet and were better than the supernatant of L. pentosus HC-2.
The present study indicates that E. faecium NRW-2 and L. pentosus HC-2 could be used as effective components in the shrimp diet and were better than the supernatant of L. pentosus HC-2. This study provided a scientific basis for the development of product safety input and the popularization and application of lactic acid bacteria in aquaculture.
•Two lactic acid bacteria strains were isolated as potential probiotics based on their antibacterial and adhesive activities.•The effects of selected strains and supernatants on the immune responses and growth performance of shrimps were different.•They enhanced the resistance of shrimps to pathogens.•Two candidates can be used as probiotic dietary supplements for shrimps.
The common or brown shrimp
Crangon crangon (L.) is a highly abundant and important taxon, both ecologically and commercially, yet knowledge on its population structure and historical biogeography is ...limited. We studied population genetic structure across the distribution range of this species by sequencing a 388
bp fragment of the cytochrome-
c-oxidase I gene for 140 individuals from 25 locations. Strong population structuring and high levels of genetic diversity were observed. Four main phylogroups were uncovered: northeastern Atlantic, western Mediterranean, Adriatic Sea and Black Sea. Gene flow of these shrimp across known oceanographical barriers (e.g., the Strait of Gibraltar and/or Oran-Almeria front, Sicilian Straits, and Turkish Straits) is severely restricted. The oldest and most variable populations currently inhabit the western Mediterranean. The observed absence of structure across the entire northeastern Atlantic shelf is proposed not to be due to gene flow, but to relatively recent colonization following the glacial cycles of the late Pleistocene. Black Sea shrimp are currently disconnected from Mediterranean populations, and colonization is inferred, on the basis of coalescent analysis, to have happened relatively recently, but possibly earlier than 7000 years ago. We postulate the hypothesis that
C. crangon survived the last brackish-water (<7‰) period inside the Black Sea and/or one of the adjacent inland seas. We conclude that (1) common shrimp populations from different basins are strongly differentiated, (2) gene flow across basins is probably very limited, and (3) the biogeographic history of the taxon is largely in accordance with the geographic history of its distribution range. This study provides further evidence that high population connectivity of marine species (e.g., by policy makers) should not be assumed.
We summarize what is known of the biophysical interactions that control vertical migration and dispersal of decapod larvae, asking the following main questions: How common is vertical migration in ...decapod crustacean larvae? What is the vertical extent of the migrations? What are the behavioural mechanisms that control vertical migrations? How does vertical migration interact with the physics of the ocean to control the dispersal of larvae? These questions are analysed by first giving a synopsis of the physical processes that are believed to significantly affect horizontal transport, and then by describing migration patterns according to taxon, to ecological category based on the habitat of adults and larvae, and to stage within the larval series. Some kind of vertical migration has been found in larval stages of virtually all species that have been investigated, irrespective of taxonomic or ecological category. Most vertical migration schedules have a cyclic nature that is related to a major environmental cyclic factor. Tidal (ebb or flood) migration and daily (nocturnal and twilight) migration are the two types of cyclic migration that have been identified. In general, all species show some type of daily migration, with nocturnal migration being the most common, whereas tidal migrations have only been identified in species that use estuaries during part of their life cycle. Moreover, there are several examples indicating that the phasing and extent of migration both change throughout ontogeny. Reported ranges of vertical displacement vary between a few metres in estuaries and several tens of metres (sometimes more than 100 m) in shelf and oceanic waters. Vertical movements are controlled by behavioural responses to the main factors of the marine environment. The most important factors in this respect are light, pressure and gravity, but salinity, temperature, turbulence, current and other factors, also influence behaviour. Many of these factors change cyclically, and the larvae respond with cyclic behaviours. The type of response may be endogenous and regulated by an internal clock, as in the case of some tidally synchronised migrations, but in most cases it is a direct response to a change in an environmental variable, as in diel migration. The reaction of the larvae to exogenous cues depends both on the rate of change of the variable and on the absolute amount of change. A series of dispersal types, involving different spatial and temporal scales, have been identified in decapod larvae: retention of the larval series within estuaries; export from estuarine habitats, dispersal over the shelf, and reinvasion of estuaries by the last stage; hatching in shelf waters and immigration to estuaries by late larvae or postlarvae; complete development on the shelf; and hatching in shelf waters, long-range dispersal in the ocean, and return to the shelf by late stages. In all of these cases, vertical migration behaviour and changes of behaviour during the course of larval development have been related to particular physical processes, resulting in conceptual mechanisms that explain dispersal and recruitment. Most decapod larvae are capable of crossing the vertical temperature differences normally found across thermoclines in natural systems. This ability may have significant consequences for horizontal transport within shelf waters, because amplitude and phase differences of the tidal currents across the thermocline may be reflected in different trajectories of the migrating larvae.
Rimicaris exoculata (Decapoda: Bresiliidae) is one of the dominant species of hydrothermal vent communities, which inside its gill chamber harbors ectosymbioses with taxonomic invariability while ...compositional flexibility. Several studies have revealed that the establishment of symbiosis can be initiated and selected by innate immunity-related pattern recognition receptors (PRRs), such as C-type lectins (CTLs). In this research, a CTL was identified in R. exoculata (termed RCTL), which showed high expression at both mRNA and protein levels in the scaphognathite, an organ where the ectosymbionts are attached outside its setae. Linear correlationships were observed between the relative quantities of two major symbionts and the expression of RCTL based on analyzing different shrimp individuals. The recombinant protein of RCTL could recognize and agglutinate the cultivable γ-proteobacterium of Escherichia coli in a Ca2+-dependent manner, obeying a dose-dependent and time-cumulative pattern. Unlike conventional crustacean CTLs, the involvement of RCTL could not affect the bacterial growth, which is a key issue for the successful establishment of symbiosis. These results implied that RCTL might play a critical role in symbiotic recognition and attachment to R. exoculata. It also provides insights to understand how R. exoculata adapted to such a chemosynthesis-based environment.
•Indispensable ectosymbionts occur in the hydrothermal vent shrimp R. exoculata.•High expression of RCTL is linearly correlated with quantities of two major symbionts.•rRCTL selectively recognize and agglutinate E. coli in a Ca2+-dependent manner.•RCTL contributes to selectivity and stability of symbioses in R. exoculata.
Growing evidence has demonstrated that microplastics (MPs) are available for a wide range of marine organisms, with filter-feeding bivalves and crabs being especially vulnerable. The crab Neohelice ...granulata is considered a key and structuring species in the Bahía Blanca Estuary (BBE) (SW Atlantic) and its ecological role makes this species especially vulnerable to several pollutants. In this study, male specimens of N. granulata and water samples were collected at three sites in the BBE for the presence of MPs. Different types of MPs were found in all the crabs and the water column samples, although the most frequent were fibers <500–1500 μm, mainly blue. This is the first study to identify MPs in the gills and digestive tract of N. granulata. Moreover, gills presented higher total abundances of MPs than the digestive tract, which suggests that in this case the main uptake of MPs would be by adherence to the gills.
•Microplastics (MPs) were identified in Neohelice granulata and in the water column from the Bahía Blanca Estuary.•The most frequent MPs were blue fibers <500–1500 μm•Gills presented higher abundances of MPs than the digestive tract.•In N. granulata the main uptake of MPs would be by adherence to the gills.
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