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A Dynamic Energy Budget (DEB) model for simulation of growth and bioenergetics of blue mussels (Mytilus edulis) has been tested in three low seston sites in southern Norway. The observations comprise four datasets from laboratory experiments (physiological and biometrical mussel data) and three datasets from in situ growth experiments (biometrical mussel data). Additional in situ data from commercial farms in southern Norway were used for estimation of biometrical relationships in the mussels. Three DEB parameters (shape coefficient, half saturation coefficient, and somatic maintenance rate coefficient) were estimated from experimental data, and the estimated parameters were complemented with parameter values from literature to establish a basic parameter set. Model simulations based on the basic parameter set and site specific environmental forcing matched fairly well with observations, but the model was not successful in simulating growth at the extreme low seston regimes in the laboratory experiments in which the long period of negative growth caused negative reproductive mass. Sensitivity analysis indicated that the model was moderately sensitive to changes in the parameter and initial conditions. The results show the robust properties of the DEB model as it manages to simulate mussel growth in several independent datasets from a common basic parameter set. However, the results also demonstrate limitations of Chl a as a food proxy for blue mussels and limitations of the DEB model to simulate long term starvation. Future work should aim at establishing better food proxies and improving the model formulations of the processes involved in food ingestion and assimilation. The current DEB model should also be elaborated to allow shrinking in the structural tissue in order to produce more realistic growth simulations during long periods of starvation.  相似文献   

3.
The biotransformation of xenobiotics by microsomal cytochromes P450 is known to be pivotal in the effects of some compounds, and thought to be so for many. A knowledge of CYP gene diversity and CYP function and regulation in aquatic species is pursued, expecting that it will disclose mechanisms, allow predictions regarding species differences in susceptibility, and provide markers for exposure to xenobiotics. As well, it is hoped that such knowledge will provide clues to CYP endogenous functions, and to the origin and functional significance of CYP gene diversity. The knowledge of CYP in marine and other aquatic species is expanding rapidly. The diversity of CYP genes in non-mammalian vertebrates may approximate that in mammals. At present, cloning studies have identified members of gene families 1 to 4 have been cloned from one or more fish species. Where known, the gene structures of fish CYP genes are like those of mammalian homologues. Only one CYP1A gene has been identified in most fish species examined. Fish CYP1As, including multiple forms from recent divergence in some genera, have structural and catalytic properties more like CYP1A1, but also have properties that are 1A2-like, consistent with fish CYP1As representing the CYP ancestral to both CYP1A1 and CYP1A2. A number of genes cloned from several species have been classified in the 3A subfamily. Fish CYP3As catalyze steroid 6β-hydroxylase, and have other properties consistent with mammalian 3As. Recently identified CYP4 genes classify to novel subfamilies but apparently are homologues of mammalian CYP4 genes, and may act on similar substrates. The greatest diversity of fish CYP genes is in family 2; there are now six fish CYP2 subfamilies known. Four of these are novel subfamilies, although cladistic analysis suggests distinct relationships to mammalian CYP2 subfamilies. Heterologous expression and characterization of some of these CYP have identified similar functions among genes in different subfamilies. For example, fish CYP2Ns and CYP2Ps are related to mammalian CYP2Js, and CYP2P3 and CYP2J2 have strikingly similar functions as fatty acid epoxygenases and hydroxylases, with nearly identical regio- and enantioselectivity for metabolism of arachidonic acid. In addition to sequence and catalytic similarities, there also are indications that CYP regulation, tissue and cellular localization are similar between fish and mammals. Yet even in cases where orthology is strongly suggested, e.g. CYP1A, there appear to be taxonomic differences in active site structure suggesting potential differences in involvement of CYP1A in toxicity. In contrast to fish, CYP diversity and functions in aquatic invertebrates are poorly known. Investigators have identified novel gene families and subfamilies in crustaceans (CYP2L; CYP45), molluscs (CYP30, CYP10) and sponges (CYP38). CYP4C genes occur in crustaceans, molluscs and echinoderms, and a new subfamily (CYP4Y) in molluscs. The future? There is no doubt that new CYP will continue to be discovered in non-mammalian vertebrates; some (e.g. CYP51) can be predicted confidently. And, there is no doubt that the numbers known in invertebrates will expand greatly. In insects and C. elegans the numbers are very high, and even slime molds have 18 CYP genes. It is virtually certain that CYP genes with unique functions will be discovered. While the knowledge of CYP genes is increasing, knowledge of CYP function and regulation lag well behind. Technical approaches to speed the aquisition of such knowledge are available. The information will be essential to discern the role that CYP play in the disposition and toxicity of xenobiotics, during development as well as in adults. Yet, when such data are in hand, we may have to face the paucity of information on the diversity, function and regulation other enzymes, notably the glutathione S-transferases, glucuronyl transferases and sulfotransferases, in aquatic species. Discerning orthologous relationships among CYP genes, as well as those for phase II enzymes, could highlight gene lineages associated with conserved and endogenous functions. Understanding CYP endogenous functions, as well as their metabolism of xenobiotics, may reveal fully the ways that chemicals cause toxicity. [Support: Sea Grant NA46RG0470-R/P61, EPA R-829890, NIH ES07381].  相似文献   

4.
Organisms adopt different sets of physiological, behavioural and morphological trade-offs in order to cope with natural environmental fluctuations. This has consequential rebounds on ecological processes and population dynamics. Such aspects become crucial for sex-dimorphic species, where sex-specific growth variation could mirror different tactics both in energy acquisition and investment between maximum female and male body size with cascading effects on population demography. To date, different approaches have been used in order to understand the causes of individual growth rate changes in ectotherm indeterminate growers, most of which failed. Here, we propose the use of a mechanistic model based on the Dynamic Energy Budget theory (DEB; Koojiman, 2010) to investigate potential differences in energy allocation strategies adopted by individuals of different genders with the Mediterranean toothcarp Aphanius fasciatus (Valenciennes, 1821) as the model species. We collected literature and field data in order to study differences in energy allocation strategies between females and males of the same species by generating projections of possible growth performances: (1) throughout their entire life span and (2) under a context of varying functional responses. Generally, the present exercise of simulations returned different patterns of growth performance among females and males of A. fasciatus, with the former being able to better optimize energetic trade-offs under optimal environmental conditions. The present DEB parameterization exercise represents an essential step towards developing a mechanistic approach to depict metabolic strategies, which are at the base of observed sexual differences, and how such differences may impair ultimate fitness at individual and, therefore, population levels.  相似文献   

5.
Organisms have evolved a highly conserved cellular response called the heat-shock or stress proteins response (SPR) that increases their tolerance to adverse environmental conditions. We have tested the hypothesis that the tissues of two molluscs, Mytilus edulis and Collisella pelta, respond to stressful situations by eliciting this response. We found that both heat-shock and Cd can induce the SPR in both species and are presently carrying out experiments to correlate the induction of stress proteins with an increased capacity to tolerate subsequent stressful conditions. These experiments should help us determine if the SPR plays an important role in the physiological adaptation of these species to their environment.  相似文献   

6.
The physiological costs of living in seawater likely influenced the secondary evolutionary transitions to marine life in tetrapods. However, these costs are alleviated for species that commute between the land and the sea, because terrestrial habitats can provide frequent access to fresh water. Here, we investigate how differences in the ecology and physiology of three sea krait species (Laticauda spp.) interact to determine their environmental tolerances and geographic distributions. These three species vary in their relative use of terrestrial versus marine environments, and they display concomitant adaptations to life on land versus at sea. A species with relatively high dehydration rates in seawater (Laticauda colubrina) occupied oceanic areas with low mean salinities, whereas a species with comparatively high rates of transcutaneous evaporative water loss on land (Laticauda semifasciata) occupied regions with low mean temperatures. A third taxon (Laticauda laticaudata) was intermediate in both of these traits, and yet occupied the broadest geographic range. Our results suggest that the abilities of sea kraits to acquire fresh water on land and tolerate dehydration at sea determine their environmental tolerances and geographic distributions. This finding supports the notion that speciation patterns within sea kraits have been driven by interspecific variation in the degree of reliance upon terrestrial versus marine habitats. Future studies could usefully examine the effects of osmotic challenges on diversification rates in other secondarily marine tetrapod species.  相似文献   

7.
Total mercury concentrations were determined in surficial sediments, eleven species of benthic organisms and six species of fish from Haifa Bay, Israel. The results show that essentially all of the shallow water zone of the Bay receives anthropogenic mercury. A mercury-cell chlor-alkali plant was identified as the source of pollution. Surficial sediments in the vicinity of the plant, containing up to 0·99 μg Hg/g dry weight, were up to 157 times enriched in mercury relative to an unpolluted area. Mercury levels in the benthic organisms reflected the levels in the sediments. Maximal concentrations reaching 38·7 and 18·2 μg Hg/g dry weight were found in the carnivorous gastropod molluscs Arcularia circumcinta and Arcularia gibbosula, respectively. In all fish species, specimens caught in Haifa Bay had higher mercury concentrations in the muscle tissue than specimens caught south of the Bay. A maximal value of 1·66 μg Hg/g wet weight was recorded in Diplodus sargus.  相似文献   

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Geographical patterning of fish diversity across coral reef seascapes is driven by many interacting environmental variables operating at multiple spatial scales. Identifying suites of variables that explain spatial patterns of fish diversity is central to ecology and informs prioritization in marine conservation, particularly where protection of the highest biodiversity coral reefs is a primary goal. However, the relative importance of conventional within‐patch variables versus the spatial patterning of the surrounding seascape is still unclear in the ecology of fishes on coral reefs. A multi‐scale seascape approach derived from landscape ecology was applied to quantify and examine the explanatory roles of a wide range of variables at different spatial scales including: (i) within‐patch structural attributes from field data (5 × 1 m2 sample unit area); (ii) geometry of the seascape from sea‐floor maps (10–50 m radius seascape units); and wave exposure from a hydrodynamic model (240 m resolution) for 251 coral reef survey sites in the US Virgin Islands. Non‐parametric statistical learning techniques using single classification and regression trees (CART) and ensembles of boosted regression trees (TreeNet) were used to: (i) model interactions; and (ii) identify the most influential environmental predictors from multiple data types (diver surveys, terrain models, habitat maps) across multiple spatial scales (1–196,350 m2). Classifying the continuous response variables into a binary category and instead predicting the presence and absence of fish species richness hotspots (top 10% richness) increased the predictive performance of the models. The best CART model predicted fish richness hotspots with 80% accuracy. The statistical interaction between abundance of living scleractinian corals measured by SCUBA divers within 1 m2 quadrats and the topographical complexity of the surrounding sea‐floor terrain (150 m radius seascape unit) measured from a high‐resolution terrain model best explained geographical patterns in fish richness hotspots. The comparatively poor performance of models predicting continuous variability in fish diversity across the seascape could be a result of a decoupling of the diversity‐environment relationship owing to structural degradation leading to a widespread homogenization of coral reef structure.  相似文献   

10.
The deep‐sea floor is increasingly subject to anthropogenic impacts. Consequently, there are increasing efforts to develop appropriate management strategies. Species‐level indicators and assessments are hampered in the deep sea by the high proportion of unknown species routinely encountered. If environmental management is to keep pace with exploitation, alternative approaches including higher taxon surrogacy (taxonomic sufficiency) must be considered. Here we compare genus‐ and species‐level studies of the diversity and ecology of deep‐sea macrobenthos on the West Shetland Slope (NE Atlantic). This is an environmentally complex region that encompasses a biogeographic transition from temperate North Atlantic to Arctic conditions, and so may be particularly challenging for any general relationship between species‐ and genus‐level analyses. We ask two questions: (i) does genus diversity reflect species diversity and (ii) does genus‐level ecology reflect species‐level ecology? We conclude that among the West Shetland Slope macrobenthos: (i) genus‐level α‐ and β‐diversity measures are highly correlated with and good predictors of their species‐level equivalents and (ii) that their ecology is very well described by genus‐level data. We further note that, given the complexity of the West Shetland Slope environment, it may be reasonable to expect these conclusions to hold in other deep‐sea environments.  相似文献   

11.
Genotoxic effects were evaluated in the somatic and gonadal cells of bivalve and gastropod molluscs inhabiting different sites of Klaip da port area in Lithuania. The occurrence of aneuploidy and polyploidy of cells, meiotic injures, centromere dissociation and fragmented polyploid nuclei as cytogenetic indicators of environmental stressors was assessed in snails Lymnaea ovata . The highest level of environmental genotoxicity (in 43.2 and 46.2% of studied cells) was observed in the tissues of snails inhabiting Malk Bay in 1995 and 1996. Dredging and thus removal of contaminated sediments from Malk Bay resulted in significant decrease (up to 27.2% in 1999) of cytogenetic injures in molluscs studied over the period from 1997 to 1999. However, the frequency of cytogenetic disturbances in molluscs from Vilhelmo Channel was increasing (1.8 times) from 1995 to 1999. Therefore, the ecological safety of the biggest drinking water supply for Klaip da population became questionable. Assessment of cytogenetic damage in Mytilus edulis (MN test) and the crustacean, Balanus improvisus, (aneugenic effects) inhabiting the Baltic Sea at B ting oil terminal has shown the highest genotoxicity level in the zone of sewage effluents from Palanga town and Ma eikiai oil refinery plant. Extensive cytogenetic injuries in gonadal cells indicated the potential long-term hazards of pollutants to ecological health and integrity of aquatic species.  相似文献   

12.
A total of 219 deep-sea fishes belonging to five families were examined for the parasite fauna and stomach contents. The demersal fish Macrourus berglax, bathypelagic Bathylagus euryops, and mesopelagic Argentina silus, Borostomias antarcticus, Chauliodus sloani, and Lampanyctus macdonaldi were caught at 243–708 m trawling depth in the Greenland and the Irminger Sea in 2002. A total of 21 different parasite species, six Digenea, one Monogenea, two Cestoda, seven Nematoda, one Acanthocephala, and four Crustacea, were found. The parasite diversity in the meso- and bathypelagic environment was less diverse in comparison to the benthal. Macrourus berglax had the highest diversity (20 species), usually carrying 4–10 different parasite species (mean 7.1), whereas Bathylagus euryops harbored up to three and Argentina silus, Borostomias antarcticus, Chauliodus sloani and Lampanyctus macdonaldi each up to two species. Most Digenea, Cestoda, Nematoda, Acanthocephala, and Crustacea are known from a wide host range. Several of the encountered parasites occurred at a very low prevalence (<10%), indicating that the studied deep-sea fishes are most probably not instrumental to complete the parasite life cycles in the area of investigation. It is suggested that the lack of nutrients in the meso- and bathypelagial limits the abundance of potential first intermediate hosts of nematodes and cestodes, resulting in low infestation rates even of widely distributed, non-specific species. In contrast, the higher biomass in the benthic deep-sea environment increases the availability of potential intermediate hosts, such as molluscs for the digeneans, resulting in increased parasite diversity. Because many deep-sea fish have a generalistic feeding behavior, the observed different parasite diversity reflects a different depth range of the fish and not necessarily a specific fish feeding ecology.  相似文献   

13.
Acceleration of metabolism is defined as a long-term increase of respiration, that is faster than the typical trajectory during the life cycle of an individual, from embryo to adult. The Dynamic Energy Budget (DEB) model is used to quantify the typical trajectory. All DEB parameters were estimated for over 300 animal species from most large phyla and all chordate classes. The goodness of fit is generally excellent, including embryo development (embryo weight, respiration, amount of yolk). Although many species match predictions for metabolic rates, particular taxa, including all those with larval development, but also ones with less clear larval stages, deviated and have a lower metabolic rate as embryo, compared to late juvenile and adult stages: they accelerate their metabolism during the life cycle. Five different types of acceleration are identified, examples are given, and methods are presented to recognise these different types. Associated life history traits are discussed in an evolutionary and ecological context. Arguments are presented for why accelerating species have an extra slow start of metabolism and why parental care evolved in endotherms.  相似文献   

14.
Effective management of marine ecosystems is enhanced when detailed information on biodiversity is available. Key information to underpin management actions and conservation planning includes relationships between species assemblages and environmental gradients, and information on species distributions. We conducted a subtidal biodiversity assessment of surface‐dwelling subtidal molluscs in eight a priori defined habitat types using underwater visual censuses to quantitatively explore relationships between molluscan assemblages, and their correlation with benthic habitats and abiotic variables. In addition, variations in diversity were examined for two key habitat types (areas dominated by Dendronephthya australis and by filter feeders) over a period of 15 months to examine temporal change. We found that molluscs form distinct assemblages within subtidal habitats, but that assemblages within key habitats show inherent temporal variability. Regional (gamma) diversity of molluscs was found to result from a combination of: (i) within habitat alpha diversity, which increased with habitat complexity; (ii) between habitat beta diversity, with significant differences in molluscan assemblages amongst habitats with differing benthic growth, substrate type, and depth; and (iii) temporal beta diversity, with significant changes detected in molluscan assemblages over time. The results demonstrate how habitats and abiotic variables (principally depth and substrate type) combine to contribute to molluscan biodiversity in temperate estuaries, and illustrate the value of these factors as surrogates for surface‐dwelling subtidal molluscs in conservation planning.  相似文献   

15.
了解生物群落中物种共存机制是群落生态学研究的重要组成部分.鉴于河口鱼类群落结构与温盐等理化因子密切相关,同时多数鱼类产卵、育幼在时间上具有同步性(主要在春夏季发生),因此环境过滤机制可能是促使河口鱼类时间上共存的主要机制.为证实该假设,本研究以长江口鱼类群落为例,利用广义可加非线性模型(GAMs)分析其时间生态位及鱼类与环境因子的关系,同时基于零模型(null models)从生态位利用的角度阐述河口鱼类群落时间上的共存机制.结果表明:鱼类物种间实测生态位大于预期值,揭示出环境过滤机制是促使鱼类时间上共存的主要机制;多数鱼类物种与非生物环境因子关系拟合较好,说明未知因素(如物种间的竞争作用等机制)对其分布影响权重较小.上述结果支持环境过滤学说是长江口鱼类物种时间共存格局的主导机制.  相似文献   

16.
Nrf2参与水生动物氧化应激调控的研究进展   总被引:1,自引:0,他引:1  
环境变化会诱导机体活性氧(reactive oxygen species, ROS)水平升高,从而产生氧化应激。氧化应激对所有生物的生存、生长、发育和进化都具有深远的影响。核因子E2相关因子2 (nuclear factor erythroid 2 related factor 2, Nrf2)被公认为细胞氧化应激调控的主导者,与伴侣蛋白Kelch样环氧氯丙烷相关蛋白1 (kelch-like ECH-associated protein 1, Keap1)一起控制数百个解毒酶和抗氧化蛋白编码基因的表达。近年来, Nrf2在水生动物中逐渐获得重视,并在一些模式鱼类如斑马鱼、鲤鱼及其他一些鱼类和水生无脊椎动物中得到研究。介绍了Nrf2的结构以及调控机制,回顾了近年来水生动物Nrf2通路参与氧化应激调控所取得的进展。研究表明, Nrf2在水生动物中广泛存在,在非生物(金属、有机污染物、无机盐、药物及微塑料等)、生物(细菌、病毒、有毒藻类)以及生境变化(冰融、盐胁迫)诱导的氧化应激调控中发挥重要作用。Nrf2一经激活入核,在小Maf蛋白的协助下与抗氧化反应元件(antioxidant-responseelement,ARE)结合,启动一系列ARE驱动基因的表达,并和孕烷X受体(pregnane X receptor, Pxr)、丝裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)以及芳烃受体(arylhydrocarbonreceptor,AhR)等细胞通路协同作用参与一系列生理过程。Nrf2在水生动物响应环境变化过程中发挥重要的细胞保护机制,有望发展成为抗逆育种潜在的基因靶点。  相似文献   

17.
The quantitative aspects of growth and reproduction in four flatfish species (plaice, flounder, dab, sole) in terms of energy flow are described on the basis of a dynamic energy budget (DEB theory). This theory consists of general assumptions about energy uptake, storage and utilisation and describes an individual by two state variables: structure and reserve, whereby body size exerts its influence through the ratio between surface area and volume. Comparison between model estimates and field data shows that the DEB model successfully describes the energetics of growth and reproduction in a number of flatfish species. Differences between species could be captured in the same model using different parameter values. Intraspecific differences in growth between males and females are mainly caused by differences in maximum surface area-specific ingestion rates. Differences between species are reflected in the surface area-specific maximum ingestion rate, the energy partitioning over growth and reproduction, and in egg volume. According to these parameters at 283 K (10°C), the species could be ranked as follows: surface area-specific maximum ingestion rate (W m−2) plaice: 56.6; flounder: 54.5; sole: 45.1 and dab: 36.1 W m−2. Fraction of energy allocated to reproduction (–): flounder: 0.35; plaice: 0.15; dab: 0.15 and sole 0.10. As a consequence of these differences in surface area-specific maximum ingestion rate and in the fraction of utilised energy allocated to reproduction, the gonad masses (g) of females of 0.5 kg wet mass differ considerably: flounder: 149 g; plaice: 86 g; sole: 70 g; and dab: 69 g. However, due to differences in egg size between species, the potential annual egg production shows a completely different pattern: dab: 2200 103; flounder: 1560 103; sole: 343 103 and plaice: 130 103 eggs.  相似文献   

18.
In this study the biotransference of selenium copper, cadmium, zinc, arsenic and lead was measured in a contaminated seagrass ecosystem in Lake Macquarie, NSW, Australia, to determine if biomagnification of these trace metals is occurring and if they reach concentrations that pose a threat to the resident organisms or human consumers. Selenium was found to biomagnify, exceeding maximum permitted concentrations for human consumption within carnivorous fish tissue, the highest trophic level examined. Selenium concentrations measured within carnivorous fish were also above those shown to elicit sub-lethal effects in freshwater fish. As comparisons are made to selenium concentrations known to effect freshwater fish, inferences must be made with caution. There was no evidence of copper, cadmium, zinc or lead biomagnification within the food web examined. Copper, cadmium, zinc and lead concentrations were below concentrations shown to elicit adverse responses in biota. Copper concentrations within crustaceans M. bennettae and P. palagicus were found to exceed maximum permitted concentrations for human consumption. It is likely that copper concentrations within these species were accumulated due to the essential nature of this trace metal for many species of molluscs and crustaceans. Arsenic showed some evidence of biomagnification. Total arsenic concentrations are similar to those found in other uncontaminated marine ecosystems, thus arsenic concentrations are unlikely to cause adverse effects to aquatic organisms. Inorganic arsenic concentrations are below maximum permitted concentrations for human consumption.  相似文献   

19.
所有脊椎动物生殖均受下丘脑-垂体-性腺轴的调控,多种下丘脑神经肽参与了生殖调控过程。大多数神经肽具有促进生殖的功能,例如促性腺激素释放激素(gonadotropin-releasinghormone,GnRH)、神经激肽B (neurokinin B, NKB)、神经肽Y (neuropeptide Y, NPY)、神经分泌素(secretoneurin, SN)、刺鼠相关蛋白(agouti-related peptide, AgRP)、甘丙肽(galanin, GAL)和吻素(kisspeptin, Kiss)。Spexin (SPX)是一种新型下丘脑神经肽,属于SPX/GAL/Kiss家族成员。SPX的成熟肽由14个氨基酸组成,该氨基酸序列在不同物种间高度保守。SPX可以激活GAL受体2和3 (GALR2/3)参与生殖、摄食等多种生理过程。本文围绕鱼类SPX基因鉴定、进化分析、组织分布、表达调控、生理功能以及信号转导机制等方面,简要总结鱼类SPX及其受体的研究进展,以期为后续深入研究提供参考。  相似文献   

20.
Data on demersal fish abundance, distribution, and spatial variation in community composition are given for Vancouver harbour and a far field reference station in outer Howe Sound. Flatfish (F. Pleuronectidae) were the dominant taxa in the trawl sampling, with the English sole (Pleuronectes vetulus) one of the most abundant species, especially in Port Moody Arm. Cluster and ordination analyses suggested a different community in Port Moody Arm relative to the outer harbour and the reference site. Length data from English sole suggested the Vancouver harbour fish may be from a different population relative to the far field reference station, with more juveniles in the harbour. Both male and female English sole were older and larger in Port Moody Arm and females were more common in this area. Growth rates of female English sole were slower at Port Moody and Indian Arm in comparison to the central harbour. Feeding habits of English sole were different at various parts of the harbour, with possible implications for contaminant uptake. The diet of English sole was dominated by polychaetes in Port Moody Arm and by bivalve molluscs at the far field reference station. Fish from the middle and outer harbour fed on a mixture of polychaetes, bivalve molluscs, and crustaceans enabling multiple pathways for bioaccumulation of pollutants.  相似文献   

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