岸蟹（Carcinus maenas）金属硫蛋白cDNA及其基因的克隆

利用已知的Ｃ．ｍａｅｎａｓ金属硫蛋白氨基酸序列资料,用全简并的ＰＣＲ引物,从鳃组织总ＲＮＡ中扩增出两种金属硫蛋白ｃＤＮＡ片断,并将其克隆到ｐＧＥＭ－Ｔ载体中,序列测定表明,其中一种ｃＤＮＡ片断核苷酸序列和推知的Ｃ．ｍａｅｎａｓ金属硫蛋白核苷酸序列完全吻合;另一种ｃＤＮＡ片断则在３’端有较大变异。根据前者ｃＤＮＡ片段序列设计特异性引物,扩增并克隆了其编码区全长ｃＤＮＡ和其编码基因,测序结果表明,岸蟹     

Carotenoids and carotenoid metabolism in Carcinus maenas (Crustacea: Decapoda)

The carotenoid pigments of the hepatopancreas, ovaries and epidermis of Carcinus maenas were investigated. The following pigments were identified: β-carotene, δ-carotene, echinenone, isocryptoxanthin, canthaxanthin, lutein, zeaxanthin, flavoxanthin and astacene.
The relative abundance of these pigments in the three tissues and the presence of possible hydroxy and keto intermediates suggest the metabolism of astaxanthin from β-carotene. The metabolic pathway in Carcinus is discussed in relation to recent studies on other invertebrates.     

Carotenoids and carotenoid metabolism in Carcinus maenas (Crustacea: Decapoda)

The carotenoid pigments of the hepatopancreas, ovaries and epidermis of Carcinus maenas were investigated. The following pigments were identified: β-carotene, δ-carotene, echinenone, isocryptoxanthin, canthaxanthin, lutein, zeaxanthin, flavoxanthin and astacene.
The relative abundance of these pigments in the three tissues and the presence of possible hydroxy and keto intermediates suggest the metabolism of astaxanthin from β-carotene. The metabolic pathway in Carcinus is discussed in relation to recent studies on other invertebrates.     

Moulting synchrony in green crabs (Carcinus maenas) from Prince Edward Island,Canada

The growth and spread of non-indigenous green crabs (Carcinus maenas) in Atlantic Canada is of concern to the sustainability of shellfish resources, particularly in areas recently invaded. Commercial green crab fishing has been initiated on Prince Edward Island to help control this species and provide a new resource for inshore fishermen. Developing a soft-shell crab product modelled after the Venetian ‘Moleche’ would provide an economic incentive beyond the existing hard-shell crab bait market. However, answers to questions such as the timing and characteristics of green crab moulting are required. A pilot study conducted in 2014–2015 collected seven groups of crabs and held them in individual compartments for 2–4 weeks to record moulting rates and physical characteristics. We found that a synchronized ‘moulting window’ occurs during July for male crabs. Field experiments in 2015 had an average moulting rate of 34%, with group-specific rates as high as 60%. The same cohort of crabs held in the laboratory had an average moulting rate of 48%, with group-specific rates as high as 75%. We observed a gradual increase in moulting rates from early to mid-July, after which all crabs caught had recently moulted, with evidence of new carapaces on all crabs. In 2015, the moulting window followed a 5°C increase in water temperature. Regarding morphology, the presence of a ‘halo’ on the episternites of the carapace was an indicator that a crab would soon moult. These promising results represent the first step in assessing the feasibility of a soft-shell, green crab industry.     

Vitellogenocytes in the Hepatopancreas of Carcinus maenas and Libinia emarginata (Decapoda brachyura)

Summary

In addition to the ovary, the hepatopanocreas of female decapod crustaceans, Carcinus maenas, and Libinia emarginata is a source of yolk protein. The specific cells in the hepatopancreas that localize vitellogenins on tissue sections are revealed with lipovitellin-specific antiserum. These cells, designated vitellogenocytes, are believed to be responsible for vitellogenin synthesis in the hepatopanocreas. This conclusion is based upon immunolocalization which demonstrates a temporal relationship with vitellogenin synthesis in the hepatopanocreas. Specifically, when the oocytes are most active in vitellogenin uptake, the hepatopanocreas is producing vitellogenins most abundantly. Vitellogenocytes are relatively large and polymorphic, similar to the reserve-inclusion cells that were described by others. Yolk protein was not detected in other cells of the hepatopancreas, male reserve-inclusion cells, or pre-vitellogenic oocytes by the same method of staining. Vitellogenocytes resemble cyanocytes, the source of hemocyanin. Whether the vitellogenocytes and their precursors are related to other populations of hepatocytes, such as cyanocytes, is not known and has not yet been studied.     

Characterization of microsatellite loci in the European green crab (Carcinus maenas)

Carcinus maenas (Decapoda: Portunidae) has proven a highly successful invasive marine species whose potential economic and ecological impacts are of great concern worldwide. Here, we characterize 14 polymorphic microsatellite loci in C. maenas and its sister species Carcinus aestuarii. These markers will prove useful for fine‐scale genetic analyses of native and introduced populations, for assessment of the sources and routes of invasion and for evaluation of post‐invasion population dynamics.     

Comparison of Protein-Extraction Methods for Gills of the Shore Crab,Carcinus maenas (L.), and Application to 2DE

As it is well-established that protein extraction constitutes a crucial step for two-dimensional electrophoresis (2DE), this work was done as a prerequisite to further the study of alterations in the proteome in gills of the shore crab Carcinus maenas under contrasted environmental conditions. Because of the presence of a chitin layer, shore crab gills have an unusual structure. Consequently, they are considered as a hard tissue and represent a challenge for optimal protein extraction. In this study, we compared three published extraction procedures for subsequent applications to 2DE: the first one uses homogenization process, the second one included an additional TCA-acetone precipitation step, and finally, the third one associated grinding in liquid nitrogen (N₂) and TCA-acetone precipitation. Extracted proteins were then resolved using 1DE and 2DE. Although interesting patterns were obtained using 1DE with the three methods, only the one involving grinding in liquid N₂ and TCA-acetone precipitation led to proper resolution after 2DE, showing a good level of reproducibility at technical (85%) and biological (84%) levels. This last method is therefore proposed for analysis of gill proteomes in the shore crab.     

Green crab (Carcinus maenas) foraging efficiency reduced by fast flows

Predators can strongly influence prey populations and the structure and function of ecosystems, but these effects can be modified by environmental stress. For example, fluid velocity and turbulence can alter the impact of predators by limiting their environmental range and altering their foraging ability. We investigated how hydrodynamics affected the foraging behavior of the green crab (Carcinus maenas), which is invading marine habitats throughout the world. High flow velocities are known to reduce green crab predation rates and our study sought to identify the mechanisms by which flow affects green crabs. We performed a series of experiments with green crabs to determine: 1) if their ability to find prey was altered by flow in the field, 2) how flow velocity influenced their foraging efficiency, and 3) how flow velocity affected their handling time of prey. In a field study, we caught significantly fewer crabs in baited traps at sites with fast versus slow flows even though crabs were more abundant in high flow areas. This finding suggests that higher velocity flows impair the ability of green crabs to locate prey. In laboratory flume assays, green crabs foraged less efficiently when flow velocity was increased. Moreover, green crabs required significantly more time to consume prey in high velocity flows. Our data indicate that flow can impose significant chemosensory and physical constraints on green crabs. Hence, hydrodynamics may strongly influence the role that green crabs and other predators play in rocky intertidal communities.     

Multi-scale phenotype-substrate matching: Evidence from shore crabs (Carcinus maenas L.)

Phenotype-environment correlations can be caused by various overlapping ecological processes (e.g. differential mortality, phenotypic plasticity and adaptation) operating over a range of spatial and temporal scales. However, multi-scale studies of the relationship between specific traits and environmental variables are rare, even though such a holistic view may have greater predictive value than the more typical single-scale observations. Here, we investigate the relationship between cryptic colouration and environmental characteristics at a range of spatial scales for the shore crab (Carcinus maenas L.), a common intertidal species. Using existing data sets at macro-scale (10,000s m²) and meso-scale (100s m²) and previously unpublished data at a micro-scale (<1 m²) we demonstrate that phenotype-substrate associations in this species are sampling-scale invariant. The association is strongest at the micro-scale, possibly because the advantages of cryptic colouration for visual predator avoidance are dependent on close concordance between prey phenotype and the surrounding substrate. By contrast, correlations at greater spatial scales may reflect longer term processes such as phenotypic plasticity or the accumulated effects of predator mediated differential mortality.     

Size-related mating success in the shore crab Carcinus maenas (Crustacea: Brachyura)

The relationship between the size of a given mating male Carcinus maenas (L.) (Brachyura, Portunidae) and the size of the female with which it was paired was studied for 1248 pairs of crabs collected from the shore In 764 of these pairs the female was in pre-moult and so the pair were in pre-copula. In the remaining 484 pairs the female had already moulted and the pairs were in copula. There were significant correlations between the sizes of the males and females in both pre-copula and copula pairs. It was found that male Carcinus collected in mating pairs and tested in the laboratory were unable to distinguish between females in terms of their size or stage of pre-moult. The positive correlation between the sizes of males and females in mating pairs on the shore is proposed to be, in part, a function of a mechanical constraint of the size of female that a given male can hold, defend and copulate with. In addition, encounters between solitary males and males carrying females, resulting in the formation of new pairs, appear to enhance the size-related mating pattern observed.     

Modelling the biological invasion of Carcinus maenas (the European green crab)

This paper proposes a system of integro-difference equations to model the spread of Carcinus maenas, commonly called the European green crab, that causes severe damage to coastal ecosystems. A model with juvenile and adult classes is first studied. Here, standard theory of monotone operators for integro-difference equations can be applied and yields explicit formulas for the asymptotic spreading speeds of the juvenile and adult crabs. A second model including an infected class is considered by introducing a castrating parasite Sacculina carcini as a biological control agent. The dynamics are complicated and simulations reveal the occurrence of periodic solutions and stacked fronts. In this case, only conjectures can be made for the asymptotic spreading speeds because of the lack of mathematical theory for non-monotone operators. This paper also emphasizes the need for mathematical studies of non-monotone operators in heterogeneous environments and the existence of stacked front solutions in biological invasion models.     

Heterochely and handedness in the shore crab Carcinus maenas (L.) (Crustacea: Brachyura)

A large sample ofadult male Carcinus maenas was 79% right-handed and 21% left-handed. A separate sample of 207 intact adult males was divided into left-handed and right-handed crabs and four measurements were taken from all major and minor chelae. Correlation and regression analyses against carapace width on log-transformed data showed that major chelae of right-handed crabs grow proportionately higher with increasing size and the ideal mechanical advantage increases; concurrently, the fingers of the minor chelae grow proportionately longer. The data for left-handed crabs showed greater variability, especially for minor chelae, providing evidence for the concept that left-handedness arises by reversal of handedness following loss of the major chela from the right-hand side. Records of handedness in large samples of non-ocypodid heterochelous brachyuran crabs show a preponderance of right-handedness.     

Organization of a phyllobranchiate gill from the green shore crab Carcinus maenas (Crustacea,Decapoda)

Summary The phyllobranchiate gills of the green shore crab Carcinus maenas have been examined histologically and ultrastructurally. Each gill lamella is bounded by a chitinous cuticle. The apical surface of the branchial epithelium contacts this cuticle, and a basal lamina segregates the epithelium from an intralamellar hemocoel. In animals acclimated to normal sea water, five epithelial cell types can be identified in the lamellae of the posterior gills: chief cells, striated cells, pillar cells, nephrocytes, and glycocytes. Chief cells are the predominant cells in the branchial epithelium. They are squamous or low cuboidal and likely play a role in respiration. Striated cells, which are probably involved in ionoregulation, are also squamous or low cuboidal. Basal folds of the striated cells contain mitochondria and interdigitate with the bodies and processes of adjacent cells. Pillar cells span the hemocoel to link the proximal and distal sides of a lamella. Nephrocytes are large, spherical cells with voluminous vacuoles. They are rimmed by foot processes or pedicels and frequently associate with the pillar cells. Glycocytes are pleomorphic cells packed with glycogen granules and multigranular rosettes. The glycocytes often mingle with the nephrocytes. Inclusion of the nephrocytes and glycocytes as members of the branchial epithelium is justified by their participation in intercellular junctions and their position internal to the epithelial basal lamina.     

The neurosecretory system of the eyestalk of Carcinus maenas (Crustacea: Decapoda)

The optic ganglia neurosecretory cells of male and female Carcinus maenas during intermoult are distinguishable into six types based on size, location, appearance and method of secretory material release from the perikaryon. Release occurs via the sinus gland and also, in one case, directly into blood capillaries among the neurosecretory cells themselves. The sinus gland consists of axonal extensions of the neurosecretory cells; no secretory granules are produced there and nuclei observed between the axonal endings are those of ill-defined glial cells.