生贻贝取肉机的试验研究

本文围绕生贻贝取肉机是开壳取整肉,还是碎壳后取碎肉的具体实施方案及所采用的原理进行了可行性分析,最终确定“离心分离法”取碎肉做为本课题的实施方案;结合试验和分析选取主部件的结构参数和技术参数;最后介绍了样机的实验结果。

Biochemical response of the mussel Mytilus coruscus(Mytiloida:Mytilidae) exposed to in vivo sub-lethal copper concentrations

Many aquatic organisms are negatively affected by exposure to high copper concentrations. We investigated the biochemical response of the mussel Mytilus coruscus （Mytiloida： Mytilidae） to copper exposure. In vivo bioassays using M. coruscus and different copper concentrations were conducted. The activity of six biomarkers, namely superoxide dismutase （SOD）, catalase （CAT）, acid phosphatase （ACP）, alkaline phosphatase （AKP）, glutamic-oxaloacetic transaminase （GOT） and glutamic-pyruvic transaminase （GPT） were measured. Survival rates decreased with increased copper concentrations and exposure times. The LCs0 values at 48, 72, and 96 h exposure were 0.48, 0.37, and 0.32 rag/L, respectively. Within digestive glands, CAT activity increased with increasing Cu concentrations. The activity of AKP showed no significant change, while the remaining four enzymes showed decreasing activity with increasing Cu concentrations. Within the gills, AKP activity increased when the Cu concentration was 0.05 mg/L, but showed no significant changes at higher concentrations. Activity of CAT and ACP within gills tended to decrease with increasing Cu concentration. The activity of SOD and GPT decreased at an exposure concentration of 0.2 mg/L. GOT activity within gills decreased at 0.1 mg/L and increased at an exposure concentration of 0.2 mg/L. Within the adductor muscle, AKP activity increased at 0.05 mg/L but did not change at higher exposure concentrations. ACP activity within adductor muscle tissue showed no change, while activities of CAT, GOT and GPT decreased with increasing Cu concentrations. SOD activity within the adductor muscle tissue significantly decreased at the 0.02, 0.05 and 0.2 mg/L exposure concentrations. Our results show tissue specific differences for the six biomarkers in for M. coruscus. Our findings provide the basis for the establishment of reference activity levels against which biomarker changes can be estimated, and are essential preliminary steps in development of in vivo bioassays.

Fauna and standing crop of freshwater mussels in Poyang Lake, China

Freshwater mussels are a major component of the zoobenthos and they therefore play an important role in freshwater ecosystems. The community composition and the standing crop of freshwater mussels in Poyang Lake, the largest freshwater lake in China and one of two lakes connected to the Changjiang （Yangtze） River, were investigated from February 2008 to May 2009. Mussels were sampled in hydrologically and geographically distinct sampling areas. A total of 42 species and 13 genera were identified, of which 32 species were endemic to China. Two species, Unio douglasiae and Lamprotula caveata, dominated all sampling areas. The number of genera and species, and the number of species within each genus, differed significantly among sampling areas. Freshwater mussels were very abundant, with an overall density of 0.28±0.22 ind./m-＇ and biomass of 4.08±3.96 g/m^2. Significant variation observed among sampling areas and among genera was probably due to the variety of habitats among the areas sampled and to the adaptability of different freshwater mussels to environments. This study suggests that Poyang Lake and other freshwater lakes in the region are important sites of freshwater mussel biodiversity and conservation.

An integrated biomarker response index for the mussel Mytilus edulis based on laboratory exposure to anthracene and field transplantation experiments

Organic pollution is a serious environmental problem in coastal areas and it is important to establish quantitative methods for monitoring this pollution. This study screened a series of sensitive biomarkers to construct an integrated biomarker response （IBR） index using Mytilus edulis. Mussels were exposed to the polycyclic aromatic hydrocarbon anthracene trader controlled laboratory conditions and the activities of components of the glutathione antioxidant system, and the concentrations of oxidative-damage markers, were measured in the gills and digestive glands. Anthracene exposure resulted in increased levels of malondialdehyde （MDA） and superoxide radicals （O2-·）, indicating that oxidative damage had occurred. Correspondingly, anthracene exposure induced increased activities of glutathione S-transferase （GST）, glutathione peroxidase （GPx） and reduced glutathione （GSH） in digestive glands, and GPx and glutathione reductase （GR） in gills, consistent with stimulation of the antioxidant system. A field experiment was set up, in which mussels from a relatively clean area were transplanted to a contaminated site. One month later, the activities of GST, GPx and GR had increased in several tissues, particularly in the digestive glands. Based on the laboratory experiment, an IBR, which showed a positive relationship with anthracene exposure, was constructed. The IBR is suggested to be a potentially useful tool for assessing anthracene pollution.

Listeria monocytogenes in Live Mytillis galloprovincialis Collected from Butrinti Lagoon Located in South Part of Albania

In 2009, 201 samples of live bivalve mussels （Mytillus galloprovincialis） were analyzed for presence of Listeria monocytogenes. The samples were collected from three sampling points （BM l-south, BM l-north and BMl-west） in Butrinti lagoon located in the south of Albania. The examination confirmed incidence of this pathogen with average value 4.5%. Based on the results, high incidence was reported in winter with 6.7% of analyzed samples. The incidence of L. monocytogenes was also reported respectively in spring of 2009 with 4.35% and in autumn with 2.3% of controlled samples. There is no big difference in values of incidence of L. monocytogenes between summer and autumn. The northern part of the lagoon was more indicated by contamination of L. monocytogenes. Examination of 67 samples of M. galloprovincialis, collected in the northern part of this lagoon, showed five cases or about 7.5% of them to be confirmed as positive. Referring to the study results, periodic controls of the sea products, particularly of live bivalve mollusks, for presence ofL. monocytogenes remains a necessary objective of food inspection in Albania.

Annual Component Analysis of Pacific Oysters （Crassostrea gigas） and Mussels （Mytilus gallopro vincialis）

To study the change in components of Pacific oysters （Crassostrea gigas） and mussels （Mytilus galloprovincialis） over a year, their annual obesity ratio, umami components （glutamic acid and glycogen）, functional components （Zn, Mn, Cu, and vitamin B12）, and Cd and noroviruses （NoVs） contents were quantified. In oysters, the obesity ratio and chemical components showed seasonal changes depending on the spawning season. Glutamic acid content increased from November to March. In contrast, glycogen content peaked in May and November. Mineral content markedly increased during spawning. From the comparison of NoVs GI and GII strains, oyster predominately infected by the GI. A remarkable difference in NoVs contents was observed depending on the oyster farms. In mussels, glutamic acid, Zn and Cu contents were stable throughout the year. Mussels＇ Cd content was about one-fifths times lower than that found in oysters. Although the NoVs strain was affected by the collection area, mussels from both areas showed decreased NoVs contents in summer, corresponding with the consumption season of mussels in Japan. Our comparative study on the seasonal variability in the chemical components and NoVs contents in pacific oysters （C. gigas） and mussels （M. galloprovincialis） clearly showed an association with physiological and environmental factors.

Ontogenetic shift in response to prey-derived chemical cues in prairie rattlesnakes Crotalus viridis viridis

Snakes often have specialized diets that undergo a shift from one prey type to another depending on the life stage of the snake. Crotalus viridis viridis （prairie rattlesnake） takes different prey at different life stages, and neonates typically prey on ectotherms, while adults feed almost entirely on small endotherms. We hypothesized that elevated rates of tongue flicking to chemical stimuli should correlate with particular prey consumed, and that this response shifts from one prey type to another as in- dividuals age. To examine if an ontogenetic shift in response to chemical cues occurred, we recorded the rate of tongue flicking for 25 neonate, 20 subadult, and 20 adult （average SVL = 280.9, 552, 789.5 mm, respectively） wild-caught C. v. viridis to chemi- cal stimuli presented on a cotton-tipped applicator; water-soluble cues from two ectotherms （prairie lizard, Sceloporus undulatus, and house gecko, Hemidactylusfrenatus）, two endotherms （deer mouse, Peromyscus maniculatus and lab mouse, Mus musculus）, and water controls were used. Neonates tongue flicked significantly more to chemical cues of their common prey, S. undulatus, than to all other chemical cues; however, the response to this lizard＇s chemical cues decreased in adult rattlesnakes. Subadults tongue flicked with a higher rate of tongue flicking to both S. undulatus and P. maniculatus than to all other treatments, and adults tongue flicked significantly more to P. maniculatus than to all other chemical cues. In addition, all three sub-classes demonstrated a greater response for natural prey chemical cues over chemical stimuli of prey not encountered in the wild （M. musculus and H. frenatus）. This shift in chemosensory response correlated with the previously described ontogenetic shifts in C. v. viridis diet. Be-cause many vipers show a similar ontogenetic shift in diet and venom composition, we suggest that this shift in prey cue dis- crimination is likely a general phenomenon among viperid snakes.

Interactions between natural biofilm,substratum surface wettability,and mussel plantigrade settlement

Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown.Here,we examined M.galloprovincialis plantigrade settlement responses to marine biofilms(BFs)on surfaces of varying wettability.No significant difference in mussel settlement was observed on young BFs(7 d)on surfaces of differing wettability;while settlement decreased on older BFs(14,21,and 28 d)formed on low compared to high wettability surfaces.Surface wettability affected BF characteristics.The standardized harmonic mean and water contact angles values were not correlated with diatom density and chlorophyll a concentration,but were correlated with bacterial density,dry weight,and thickness.Denaturing gradient gel electrophoresis revealed that bacterial community structure differed on BFs on surfaces of varying wettability.Thus,surface wettability affects biofilm characteristics,and the subsequent changes in BF characteristics may be responsible for the variation in biofilm-inducing activity of M.galloprovincialis plantigrade settlement.