首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 53 毫秒
1.
Geographic variation in freeze tolerance, glycogen storage and freeze-induced glucose mobilisation was investigated in the earthworm Dendrobaena octaedra. Specimens from 15 populations collected in Canada, Greenland and Europe were reared in the laboratory in a common-garden experiment to test whether glucose and glycogen concentrations correlated with genetic variation in freeze tolerance among the populations. Populations from Canada, Sweden, Poland and Finland did not differ much in their freeze tolerance and were able to tolerate freezing for 18 d down to at least −14 °C (lowest temperature tested). Specimens collected in a relatively warm climate (Denmark) were the least freeze tolerant, and also had the lowest concentrations of glucose when frozen at −2 °C. However, there was no clear evidence that glucose concentration is a determinant in the degree of freeze tolerance of D. octaedra when considering the whole assemblage of populations. The role of phylogenetic inertia was tested by looking for serial independence and no influence of phylogeny was detected in our findings allowing us to exclude the possibility that phylogenetic relatedness between populations is a major evolutionary factor explaining the observed differences for freeze tolerance and related traits. The size of the glycogen reserve was significantly correlated with the ability to tolerate freezing. Large glycogen reserves may be advantageous in very cold regions in order to maximise cryoprotectant production and/or as a source of energy for the anaerobic metabolism occurring during prolonged freezing.  相似文献   

2.
The study was conducted on Dendrobaena octaedra—a small epigeic earthworm species common in different forest types. In the laboratory the P (parent animals collected in forest) and F1 generations were cultured separately in containers filled with 50 g artificial soil. The containers were kept at 15±0.5 °C, 80% humidity and constant artificial light of low intensity. Every month during the 47 months of culture, the animals and cocoons were removed from the soil by washing on a sieve, weighed, and replaced into new soil. Individuals of the F1 generation did not reproduce continuously. Cocoon production was seasonal, despite culture in constant conditions throughout the whole experiment. Reproduction was highest in spring and summer, and dropped in the winter months. Seasonality characterized the fraction of animals reproducing as well as the number of cocoons produced. The observed seasonal changes in the cocoon production of the F1 generation cultured in constant conditions suggest that internal regulation of reproduction may exist in the earthworm D. octaedra. External factors like temperature, moisture, photoperiod or food supply, which could be responsible for seasonality of reproduction were missing.  相似文献   

3.
This study examined whether earthworm (Dendrobaena octaedra) populations originating from three differently polluted mixed oak-pine forests differ in life history parameters, and whether any observed differences are adaptive. Three forests were chosen: the most polluted forest, near Olkusz, affected by a zinc smelter and on soil containing metal ore; the Niepo?omice Forest, moderately polluted by industry; and the relatively unpolluted Kampinoska Forest. Parent animals (P generation) were collected from each forest and thereafter cultured in the laboratory. From cocoons laid in the laboratory the F1 generation was reared and observed to determine whether it inherited features observed in the parent generation. To distinguish the effect of the metal studied (Cd) from that of soil edaphic conditions, individuals collected in the field were divided into two groups: one cultured in unpolluted medium, the other in medium spiked with cadmium. Earthworms originating from polluted forests (parent generation) exhibited higher cadmium storage capacity, and a higher cadmium concentration factor (cadmium in animal/cadmium in soil). No interpopulation differences in cadmium accumulation were found in their offspring (F1 generation), meaning that the cadmium accumulation ability was acclimatory and not adaptive. Cadmium in low doses negatively affected reproduction parameters: cocoon production, mass of produced cocoons, and reproductive allocation (weight of offspring divided by the weight of adults). The effect of cadmium was stronger in animals originating from the unpolluted forest than in those from the heavily polluted forest. F1 animals originating from the heavily polluted forest exhibited the highest cadmium tolerance (higher mean survival time and median survival time, lower hazard rate probability per time unit that an individual surviving to the beginning of a given interval will die within that interval). The observed tolerance to cadmium (higher reproduction, better survival) in the population from the heavily polluted forest apparently was heritable, suggesting adaptation of D. octaedra to life in a polluted environment.  相似文献   

4.
The effect of different culture methods, cold acclimation and desiccation on the supercooling point (SCP), the melting point (MP) of fluids and the quantity of water freezing (osmotically active water) was investigated in individual cocoons of Enchytraeus crypticus and an undescribed Enchytraeus species using differential scanning calorimetry (DSC) techniques. Both species can be easily cultured in the laboratory in agar where the development and hatching of the worms can be observed. Culture methods (agar with nettle leaves or oats as food and wet filter paper without food supply) had a significant effect on fresh weight and SCP of E. crypticus cocoons. The water content (as a proportion of fresh weight) was slightly lower in the cocoons from the wet filter paper cultures. Acclimation at —3 °C did not affect the supercooling ability of E. crypticus cocoons, whereas the SCP of E. sp.1 cocoons was lowered from a mean of —8.7 to —12.4 °C. The supercooling ability of cocoons of E. crypticus was only slightly increased by desiccation and cold acclimation, but the quantity of frozen water was significantly reduced with acclimation and desiccation (2 and 3 min) at room temperature. The MP values of the cocoon fluids reflected these changes in both species. No cocoons of E. crypticus and E. sp.1 survived desiccation and freezing in our experiments and no worms of Enchytraeus albidus, E. crypticus and Henlea perpusilla survived freezing to —10 or —20 °C.  相似文献   

5.
Earthworms were maintained in two types of soil-filled mesocosm. Type 1, designed for use in soil-inoculation studies, was only 0.15 m deep. Sampling revealed the position at which cocoons were deposited by earthworms in mono-species culture. Whilst adequate for shallow-working worms, larger species may have experienced restricted burrow formation and associated cocoon deposition. Therefore, Type 2 mesocosms (1.0 m deep) were also used. Here, earthworms were found to burrow throughout the soil columns, but cocoons were mainly deposited within 0.25 m of the soil surface (95% overall). The deepest cocoon deposition was at 0.4 m by Lumbricus terrestris, although 45% of the cocoons for this species were located in the upper 0.05 m of the soil, compared with 70% and 71% for Aporrectodea longa and Octolasion cyaneum, respectively. Comparisons between mesocosms showed that their depth affected cocoon distribution in the soil and that differences were also present compared with field-collected results. Reasons for this are discussed, as are implications for soil inoculation with earthworms. If cocoons are viewed as a potential inoculum for soil restoration work, their harvesting and spreading in soil may assist successful colonisation.  相似文献   

6.
Summary Although moisture requirements of Eisenia fetida are considered to be generally known, very few in-depth studies have been performed. The moisture preferences of juveniles as well as adults of this species were determined in moisture towers containing cow manure with a particle size bigger than 500 and smaller than 1000 m and an organic matter content of 54%. The clitellate worms showed a wider preference range than the juveniles but deposited most of their cocoons within the narrow range of 65%–70% moisture — a moisture range preferred by 80% of the juveniles. Growth studies of newly hatched worms at various moisture levels over a period of 90 days showed that growth rate and final biomass were influenced by moisture availability with a very low rate of growth at low as well as at high moisture levels. The change in biomass of clitellate specimens as well as their consecutively produced cocoons were monitored at different moisture levels. A clear relationship between mass of cocoons and biomass of the producing worms was established at presumably favourable moisture conditions. Furthermore, the relation between cocoon mass and the production rate of cocoons was also determined, which showed that cocoon mass increased concomitantly with increase in cocoon production. The study also showed that clitellum development was increased at moisture levels above 64%. The onset of cocoon production was, however, earliest at slightly lower moisture levels, from which it is concluded that the optimal moisture level for growth and development of clitella are not necessarily optimal for the production of cocoons.Dedicated to the late Prof. Dr. M.S. Ghilarov  相似文献   

7.
Earthworms in pastureland may be exposed to residues of veterinary medicines excreted in the faeces of treated cattle. Possible sub-lethal effects of these drugs on life history characteristics are critical to earthworm populations, but there are no internationally accepted guidelines for the laboratory testing that is essential as a supplement to field studies. In the laboratory, Lumbricus terrestris were kept in artificial soil and offered dung collected from cattle with sustained-release boluses of ivermectin or fenbendazole, or from untreated cattle (control). Earthworms were therefore exposed to drug residues in concentrations excreted naturally by treated cattle. Furthermore, worms were exposed to the drug in the natural way, i.e. by ingestion. A matrix model based on survival and reproductive rates as functions of life-stages was used to quantify the population dynamics of L. terrestris. There were no adverse effects of either ivermectin or fenbendazole on the individual survival and growth of L. terrestris. Mature worms produced on average 2-3 cocoons per worm per month irrespective of drug treatment, and about 50% of these cocoons hatched successfully. The median time to hatching (incubation time) depended on the age of the parent worms and was significantly lower for cocoons in the ivermectin group compared to controls, as the worms became older. The incubation time varied considerably in all groups; even within a batch of cocoons produced during 1 month by one pair of worms, the period sometimes varied by more than 1 year. The intrinsic rate of natural increase (r≈0.0044 d−1) was not affected by either drug treatment. The methods and the model developed in this study are suitable for long-term studies on L. terrestris and give ecologically relevant information on population dynamics. There were no negative effects of ivermectin and fenbendazole on life history characteristics of L. terrestris and it is unlikely that earthworm populations will be affected in the field following normal use of sustained-release boluses in cattle. Finally, the matrix model points to adult survival rate and cocoon viability as the most important variables to be included in future ecotoxicological tests on L. terrestris.  相似文献   

8.
Summary Although various authors have contributed to our knowledge of the biology of Eudrilus eugeniae some basic facts about the life cycle and reproduction are still not fully documented. Quantitative observations were made of the cocoons at 25 °C in different substrates. The incubation period for 166 cocoons was 16.89 days, based on cocoons produced by worms between the ages of 70 and 100 days. These cocoons produced a mean 2.12 hatchlings per cocoon after incubation in cattle manure, moist filter paper and distilled water. A smaller batch of cocoons incubated in cattle manure produced a mean of 2.7 hatchlings per cocoon. The hatching success of the cocoons was 84% in cattle manure, 50% in distilled water, and 48% on moist filter paper. The reproductive capabilities of E. eugeniae and Eisenia fetida were compared.  相似文献   

9.
Sublethal effects of terbuthylazine and carbofuran on the growth and reproduction of Eisenia andrei were investigated over a period of three generations. Reproduction was assessed by measuring the coccon production of worms treated chronically with pesticides. Inhibition of cocoon production was found in the parental generation. Hatchlings were raised from cocoons to provide the F1 generation. During raising a more rapid growth of juveniles treated with terbuthylazine was observed, compared with the growth of untreated worms. The increase in vitality was also found in cocoon production. Groups treated with terbuthylazine produced more cocoons than controls. The F2 generation was raised from hatchlings of the F1 generation, and here, also the terbuthylazine treatments increased earthworm growth, but not cocoon production. Exposure to carbofuran decreased cocoon production in all generations. Growth of the F1 generation was not influenced by low concentrations of carbofuran.  相似文献   

10.
Phenotypic diversity for agronomic characteristics was determined in an experiment with 29 landraces and 14 improved varieties of rye from the Nordic area, Germany and Poland. The accessions were scored for 12 characters. Effects of the location, year, type, and country of origin for landraces were investigated with analysis of variance. Phenotypic variations for the traits were estimated using the Shannon–Weaver diversity index. The genetic variation was high, with an average of H 0 = 0.566. The landraces from Norway, Sweden and Finland showed the highest variation, whereas the improved varieties had the lowest. The German material also had low variation but the status of this material is uncertain. The genetic diversity showed that 70% of the variation was found within the accessions. A cluster analysis was carried out to identify the relationship between the accessions. The material grouped into eight clusters, where clusters I to V included landraces from Sweden, Finland and Norway, except for cluster III, which included one improved variety from Denmark. Cluster VI comprised a single Swedish landrace from Gotland. Most of the improved varieties were in cluster VII and the last cluster contained accessions from Germany and Sweden.  相似文献   

11.
 One-week-old juveniles of Perionyx excavatus were cultured in urine-free cow manure for 16 weeks in three different seasons to find out the influence of environmental factors on growth and reproduction. The biomass of worms increased gradually until the 16th week in all seasons. There was no significant (F=2.51) variation in biomass between the three seasons; however, the growth rate varied significantly (F=50.49, P<0.01). During the pre-clitellar period, the growth rate (mg/g) increased steeply (1013.17±41.33 in the monsoon season, 728.64±15.5 in winter and 463.16±22.96 in summer) until the worms attained maturity (5–8 weeks) and from then onwards gradually decreased after the commencement of cocoon production. Worms attained maturity when the mean weight of each worm ranged from 167.46 mg to 197.13 mg. The cumulative number of cocoons varied significantly (F=26.07, P<0.01) with season. Similarly, the rate of cocoon production also varied significantly (F=62.06, P<0.01). The average rate of cocoon production was 7.23, 0.99 and 0.53/worm/week in the monsoon season, winter and summer, respectively. By week 16, the ratio of weight gain to the initial weight of 1-week-old juveniles was 1 : 43.13 in the monsoon season, 1 : 30.49 in the winter and 1 : 23.69 in the summer. The maximum mass gain, growth rate, and cocoon production and earliest attainment of maturity were recorded during the monsoon season, and were attributed to the lowest range of fluctuating temperatures and high humidity compared with during winter and summer. The growth rate of worms in all seasons was inversely proportional to the number of cocoons produced. Further, the higher the rate of cocoon production, the lower the weight of individual cocoons. Received: 1 July 1997  相似文献   

12.
Hyperiodrilus africanus (Beddard) is a 12-cm to 16-cm-long earthworm, which is widely distributed in West and Central Africa. It lives in the upper 10–20 cm of the soil, and feeds on a mixture of soil and above-ground litter. Cocoons obtained in the laboratory hatched on average 17 days after deposition and produced two juveniles on average. Paired individuals fed soil amended with 2% coffee residues grew significantly (P<0.05) faster than those in the control soil. Daily individual weight increments were respectively 6.1 mg worm–1 day–1 and 1.0 mg worm–1 day–1 in supplemented and control soil. The generation time was short, and cocoon production reached 9.6 month–1 (i.e. 115 cocoons adult–1 year–1). When H. africanus collected from the field were raised in the laboratory, they grew slowly, laid fewer cocoons and mortality was high. Demographic parameters indicated an improvement when H. africanus were raised in batches rather than individually. Mating enhanced cocoon production although parthenogenesis was possible. Received: 4 April 1997  相似文献   

13.
Temperature fluctuations are a fundamental entity of the soil environment in the temperate zone and show fast (diurnal) and slow (seasonal) dynamics. However, responses of soil ecosystem engineers, such as earthworms, to annual temperature dynamics are virtually unknown. We studied growth, mortality and cocoon production of epigeic earthworm species (Lumbricus rubellus and Dendrobaena octaedra) exposed to temperature fluctuations in root-free soil of a mid-European beech-oak forest. Both earthworm species (3 + 3 individuals of each species) were kept in microcosms containing soil stratified into L, F + H and Ah horizons. In the field, earthworm responses to smoothing of diurnal temperature fluctuations were studied, simulating possible global change. In the laboratory, earthworm responses to seasonal (±5 °C of the annual mean) and diurnal temperature fluctuations (±5 °C of the seasonal levels) were analyzed in a two-factorial design. Both experiments lasted 12 months to differentiate between seasonal and diurnal responses. In the third experiment overwintering success of both earthworm species was investigated by comparing effects of constant temperature regime (+2 °C), and daily or weekly temperature fluctuations (2 °C ± 5 °C).Temperature regime strongly affected population performance of the earthworms studied. In the field, smoothed temperature fluctuations beneficially affected population development of both earthworm species (higher biomass, faster maturity and reproduction, lower mortality). Consequently, density of both species increased faster at smoothed than at ambient temperature conditions. In the laboratory, responses of L. rubellus and D. octaedra to temperature treatments differed; however, in general, earthworms benefited from the absence of diurnal fluctuations. Total earthworm numbers were at a maximum at constant temperature and lowest in the treatment with both diurnal and seasonal temperature fluctuations. However, after one year L. rubellus tended to dominate irrespective of the temperature regime. In the overwintering experiment L. rubellus sensitively responded to even short-term winter frost and went extinct after one week of frost whereas D. octaedra much better tolerated frost conditions. Earthworms of both species which survived frosts were characterized by a significant body weight decrease during the period of frosts and fast recovery in spring suggesting a different pattern of individual resource expenditure as compared with constant +2 °C winter regime. Contrasting trends in the population dynamics of L. rubellus and D. octaedra during the frost-free period and during winter suggest that in the long-term temperature fluctuations contribute to the coexistence of decomposer species of similar trophic position in the forest litter. The results are discussed in context of consequences of climate change for the functioning of soil systems.  相似文献   

14.
Survival of adultDendrobaena rubida, cocoon production, cocoon viability, and growth of juveniles were examined in laboratory experiments when the worms were reared in acidified and metal polluted soils. Solutions of Cu, Cd and Pb were added to give total concentrations of 10, 100 and 500 μg g?1 in soils with a pH of 4.5, 5.5 and 6.5. Adult tissues, hatchlings and cocoons were analyzed for metals. D. rubida survived poorly in soils with low pH, especially in combination with Pb or Cu, which accumulated in seminal vesicles and cerebral ganglion. Cocoon production was halved when pH was lowered from 6.5 to 4.5 and metals reduced the cocoon number even more in the most acid soils. Hatching success was lower than 20 % in acidified soils. In contrast, the number of hatchlings increased when pH decreased and peaked in soils polluted with Cd. While low pH reduced the embryonic development time, metals prolonged it. Juveniles grew slowly and died early at low pH.  相似文献   

15.
Earthworms are important components of soil ecosystems worldwide, and have been used extensively as indicator species in ecotoxicology studies. Our understanding of mating systems, population structure, and genetic diversity in earthworms is limited by the current lack of available genetic tools. To address this gap, we developed 16 novel microsatellite markers for the compost earthworm Eisenia fetida, one of the most widely studied earthworm species. We tested the new markers in 3 putative populations of worms from commercial vermiculture operations in Canada and the U.S.A. All 16 loci were variable in at least one population, with the number of alleles per locus ranging from 3 to 10, observed heterozygosity from 0.000 to 0.783, and polymorphic information content from 0.032 to 0.587. One group had significantly reduced heterozygosity compared to the other 2, but overall there were only minor genetic differences among the tested suppliers, suggesting a possible bottleneck for this species in North America. The microsatellite loci we describe here will be extremely useful tools for future field and laboratory studies of E. fetida. Body size and condition in adult worms varied significantly by supplier, and breeding success and cocoon production were significantly higher in breeding pairs from one supplier compared to the other two. In the absence of evidence for genetic divergence among populations, our results suggest that the early rearing environment may be an important factor affecting adult breeding performance. We caution that the source of worms may affect the outcome of laboratory experiments involving growth and reproduction.  相似文献   

16.
氮钾肥配合施用对桑叶产量品质及蚕茧质量的影响   总被引：3，自引：0，他引：3  
通过连续4年田间施肥试验和一季养蚕试验,研究了氮肥和钾肥配合施用对桑叶产量、品质及相应桑叶喂饲家蚕对蚕生长及蚕茧品质的影响。结果表明,桑园施用氮钾肥显著提高桑叶产量,在氮钾肥各养分配比中,以高氮高钾处理(N450K300)的产量最高,比N0K0处理年均增产35.2%,与其他各处理产量差异显著。桑叶品质分析结果表明,桑叶中必需氨基酸、氨基酸总量、粗蛋白、油脂含量随氮肥用量增加而提高,但单施氮肥会对蛋氨酸和油脂含量产生负面影响;施钾导致糖分含量下降,其他品质参数值随钾肥施用而提高,氮钾肥配合施用具有提高桑叶品质的作用。养蚕结果表明,桑园增施氮钾肥生产出的桑叶,有助于降低蚕茧的死笼率、具有提高全茧量和茧层率及提高蚕茧产量的作用。蚕茧上茧率、茧丝长、解舒率和茧丝净度随着钾肥用量的增加而提高,在施钾基础上增加氮肥用量有提高蚕茧品质的作用,但不施钾只施氮肥对上茧率有负面影响,说明氮钾肥配合施用能促进蚕茧质量的提高。  相似文献   

17.
Dendrobaena veneta is an earthworm species capable of consuming a wide range of organic wastes which may be used as a field indicator of municipal sewage sludge applied to land. The aim of the present 8-week laboratory experiment was to check viability, reproduction and the immune system of D. veneta maintained in soil without food additions (control 0s group) or in soil amended with 25% or 50% municipal sewage sludge (25s and 50s groups, respectively). Reproduction and immunity are important physiological functions whose detailed study can provide information on the effects of pollutants. After the 8-week exposure period, earthworm mortality (2 out 20 individuals) was recorded only in the 50s group. Reproduction was high in the 25s group (44 cocoons and 41 juveniles) whereas reproduction was almost completely inhibited both in the food-deprived control 0s group (1 cocoon, 3 juveniles) and in the 50s group containing a high amount of sludge (2 cocoons). Significantly increased numbers of non-invasively extruded coelomocytes were recorded 3 weeks after the start of the experiment in the 50s group, but they dropped to the food-deprived control level by the end of 8 weeks likely due to exhaustion of the immune system coping with sludge-derived microbes and/or toxins. In contrast, numbers of coelomocytes in the 25s group increased gradually reaching the maximum at the end of the experiments. In conclusion, high amounts of municipal sewage sludge are detrimental to worms, inhibiting reproduction and inflicting mortality. A moderate amount of municipal sewage sludge provides a good source of nutrients for D. veneta, supporting their growth and reproduction for at least 8 weeks. Immunological parameters might serve as useful indicators of earthworm exposure to sewage sludge.  相似文献   

18.
《Applied soil ecology》2007,35(1):46-56
A study on the widespread earthworm Dendrobaena octaedra was conducted to determine which individual life history traits were the most sensitive to copper and to determine the contribution of changes in individual traits to changes in the population growth rate (λ). The study showed that the effect of copper on population growth rate mirrored the effects seen on growth, maturation and reproductive output, with stimulation at the lowest concentrations and inhibition at the highest concentration. A decomposition analysis showed that the mean change in λ was mainly driven by time between consecutive cocoon productions, except at the highest copper concentration (200 mg/kg dry soil) where decreased production of fertile cocoons also contributed to the reductions in λ. The highest population growth rate (λ = 1.18 week−1) occurred at 80 mg Cu/kg dry soil. At higher concentrations λ became gradually smaller, and was almost 1 week−1 (where no population increase or decrease occurs) at the highest exposure concentration of 200 mg Cu/kg dry soil suggesting that extinction would occur if a population of D. octaedra were to be exposed to copper concentrations only slightly higher than this level.  相似文献   

19.
家蚕种茧切削智能夹具设计与试验   总被引：1，自引：0，他引：1  
为了提高家蚕种茧切削机械的自动化和智能化水平,适应不同品种的家蚕种茧制种切削需要,该文设计研究了一种家蚕种茧切削智能夹具。该夹具具有自动调整种茧位置状态并固定种茧的功能,能够迅速、准确地将以任意方式进入夹具内的不同形状和大小的种茧,自动调整为理想切削状态并固定,使高速转动的切削刀具沿夹具顶面水平切割种茧时不会伤到蚕蛹,且削口平整、便于实现蚕蛹与茧壳的自动分离。通过对10个不同种茧品种的切削试验表明:该智能夹具自动定位与固定功能的成功率达到98%以上,刀盘切削成功率大于97%,切削伤蛹率小于2%;不同形状和大小的单粒种茧以任意方式进入夹具内,到该智能夹具将其调整固定到位并切削完成所需时间为6~8 s,对各品种的家蚕种茧具有普遍适用性。  相似文献   

20.
176 horseradish accessions from the Nordic countries Denmark, Finland, Norway and Sweden were analysed to estimate the level of genetic diversity and to propose conservation strategies for this cultivated plant. Most of the accessions were collected in old gardens of the Nordic countries but selections from European countries and Danish breeding lines were also included in the study. Since horseradish is mainly vegetative propagated the genetic diversity has been assumed to be small. However, using the AFLP method with three primer combinations we revealed a significant genetic diversity among Nordic horseradish. The analysis yielded 65 polymorphic bands and we found an overall diversity index of 0.5 (Shannon–Weaver). The highest diversity was found among the Finnish accessions followed by the Danish accessions. An overall AMOVA analysis indicated that 90 % of the variation could be explained by among accession variation. The AFLP data assigned the different accessions into groups that corresponded with their country of origin. A closer relationship was observed between the Swedish, Danish and some of the Norwegian accessions while the Finnish accessions separated more clearly from the other three countries. A possible explanation for the diversity is that horseradish probably has been introduced to the Nordic countries at many occasions during a long period of time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号