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1.
The differentiation of normal and mutant (aP/aP) Xenopus laevis melanophores in chimerae was analyzed to determine the tissues affected by this mutation. Normal melanophores in mutant host tissue differentiate in mutant host tissue prior to those of the mutant host. These normal melanophores were initially normal in appearance, but, after the differentiation of the mutant host's melanophores, they became indistinguishable from their host's melanophores. These normal melanophores persist in more than normally punctate form after the disappearance of the mutant host's melanophores in late larval life. Parabiosis and head transplants between mutant and normal embryos did not affect the character of either type of melanophore developing in tissue of its own genotype, indicating that the hormonal control of melanophore differentiation is not affected by the mutation. Therefore, the periodic albino mutant affects the capacity of the mutant melanophore to differentiate and the ability of the mutant skin to support normal melanophore differentiation.  相似文献   

2.
Chemical analysis of seeds and seedlings of the CC and cc genotypes in Melilotus alba indicated that these alleles affect flavonoid biosynthesis. The CC seed coats contained orientin and iso-orientin, which were absent in the cc seed coats. The pigment responsible for the red pigmentation of young seedlings of CC genotypes was a cyanidin glycoside. The embryos of seeds of both the CC and cc genotypes contained a flavonoid tentatively identified as a 6,8-di-C-pentosylapigenin. The observation that 3′,4′-dihydroxyflavonoids were absent in the cc genotype and that 4′-hydroxyflavonoids were present in both genotypes indicated that the C/c alleles controlled the 3′-hydroxylation of flavonoids. The C/c alleles did not, however, control 3′-hydroxylation of cinnamic acids since caffeic acid was detected in both genotypes.  相似文献   

3.
本文观察比较了体色正常及体色异常褐牙鲆 (Paralichthysolivaceus)皮肤中黑色素胞和鳞片的发生及演变过程。结果显示仔鱼鱼体两侧皮肤中最先出现星状幼体型黑色素胞 ,随着变态发育 ,有眼侧皮肤中成体型黑色素胞逐渐替代幼体型黑色素胞 ;而无眼侧皮肤中 ,幼体型黑色素胞逐渐退化崩解 ,成体型黑色素胞不出现 ,无眼侧皮肤逐渐失去色素变为白色。体色异常现象出现于变态后期 ,白化和黑化现象几乎同时发生。白化个体有眼侧皮肤中成体型黑色素胞不能正常替代幼体型黑色素胞 ,逐渐失去色素形成白色斑块。黑化个体无眼侧皮肤中成体型黑色素胞则非正常地出现 ,逐渐替代幼体黑色素胞形成黑斑。约 30日龄变态完成时 ,体色异常现象已经显著 ,已能明显区分体色正常和异常个体。 6 0日龄左右 ,幼鱼皮肤开始长出形态较为原始的圆鳞。体色正常个体有眼侧皮肤上的圆鳞会逐渐发育成栉鳞 ,无眼侧则维持圆鳞。对比分析体色异常个体的鳞片形态 ,发现有眼侧白化部位的鳞片仍为圆鳞 ,而无眼侧黑化部位的鳞片则发育为栉鳞。同时 ,通过对体色正在恢复中的白化牙鲆的鳞片观察表明 ,伴随着白化部位色素的恢复 ,该部位的圆鳞会逐渐转变为栉鳞。由此推断色素的发生与鳞片的发育密切相关  相似文献   

4.
A growing body of evidence suggests that host genetic factors play an important role both in susceptibility to HIV infection and progression to AIDS. The present study aimed at evaluating the role of IL-6 and IL-10 gene polymorphisms on the risk of HIV susceptibility and disease progression among North Indian patients. The polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques were applied to genotype IL-6 and IL-10. 300 seropositive and an equal number of age- and sex-matched seronegative control subjects were recruited for this study. There was statistically no significant variation in the frequencies of IL-6 and IL-10 genotypes among cases and controls. However, statistically non-significant association for risk of rapid disease progression was observed due to the combined effect of the IL-6 homozygous CC genotype and CC of IL-10, OR = 1.62, 95% CI = 0.38–6.91. Therefore, combined effects of the CC of IL-6 and CC of IL-10 might reduce the hosts ability to hinder viral replication after infection.  相似文献   

5.

Background and Aims

Recently, several genome-wide association studies have revealed that single nucleotide polymorphisms (SNPs) in proximity to IL28B predict spontaneous clearance of HCV infection as well as outcome following peginterferon and ribavirin therapy among HCV genotype 1 infected patients. The present study aimed to evaluate the impact of IL28B SNP variability on liver histology in the context of a phase III treatment trial (NORDynamIC) for treatment-naïve patients with chronic HCV genotype 2 or 3 infection, where pretreatment liver biopsies were mandatory.

Methods

Three hundred and thirty-nine Caucasian patients had samples available for IL28B genotyping (rs12979860) of whom 314 had pretreatment liver biopsies that were evaluated using the Ishak protocol, allowing for detailed grading and staging of liver histopathology.

Results

IL28B CCrs12979860 genotype in HCV genotype 3 infected patients was associated with higher ALT levels (p<0.0001), higher AST to platelet ratio index (APRI; p = 0.001), and higher baseline viral load (p<0.0001) as compared to patients with the CT or TT genotypes. Additionally the CCrs12979860 genotype entailed more pronounced portal inflammation (p = 0.02) and steatosis (p = 0.03). None of these associations were noted among HCV genotype 2 infected patients.

Conclusion

This study shows that the CCrs12979860 SNP is associated with more pronounced liver histopathology in patients chronically infected with HCV genotype 3, which may be secondary to higher viral load. The finding that IL28B variability did not impact on liver pathology or viral load among genotype 2 infected patients implies that IL28B may differentially regulate the course of genotype 2 and 3 infection.  相似文献   

6.
In an orange-colored variant of the medaka fish, Oryzias latipes, which is homozygous for b allele, the melanophores represent a tissue-specific differentiation, manifesting an amelanotic appearance in the skin, an incomplete melanogenesis in the choroid and the peritoneum, and mosaic phenotype-like melano-iridophores in the peritoneum. In a wild-type strain of this species carrying the B gene, all melanophores are terminally differentiated irrespective of the tissues in which they are located. This indicates that the deficiency of B gene impairs the differentiation of melanophores in the medaka. Electron microscopy disclosed that the deficiency of B gene causes deterioration of melanogenesis to occur inside the melanosomes and that the manner of deterioration in the melanophores in the skin, the choroid and the peritoneum is different. The ubiquitous occurrence of reflecting platelet-laden melanophores in the peritoneum of this variant and the total absence of a mosaicism in pigment cells of the wild-type strain indicate that the deficiency of B gene predestines melanoblasts distributed in this tissue to an ambiguous state with regard to their differentiation. Little difference is observed between melanosomes maturation in pigment epithelial cells of the orange-colored variant and the wild-type strain, indicating an innocent role of the B gene in their differentiation.  相似文献   

7.
The appearance of the pseudo-albino phenotype was investigated in developing Senegalese sole (Solea senegalensis, Kaup 1858) larvae at morphological and molecular levels. In order to induce the development of pseudo-albinos, Senegalese sole larvae were fed Artemia enriched with high levels of arachidonic acid (ARA). The development of their skin pigmentation was compared to that of a control group fed Artemia enriched with a reference commercial product. The relative amount of skin melanophores, xanthophores and iridophores revealed that larval pigmentation developed similarly in both groups. However, results from different relative proportions, allocation patterns, shapes and sizes of skin chromatophores revealed changes in the pigmentation pattern between ARA and control groups from 33 days post hatching onwards. The new populations of chromatophores that should appear at post-metamorphosis were not formed in the ARA group. Further, spatial patterns of distribution between the already present larval xanthophores and melanophores were suggestive of short-range interaction that seemed to be implicated in the degradation of these chromatophores, leading to the appearance of the pseudo-albino phenotype. The expression profile of several key pigmentation-related genes revealed that melanophore development was promoted in pseudo-albinos without a sufficient degree of terminal differentiation, thus preventing melanogenesis. Present results suggest the potential roles of asip1 and slc24a5 genes on the down-regulation of trp1 expression, leading to defects in melanin production. Moreover, gene expression data supports the involvement of pax3, mitf and asip1 genes in the developmental disruption of the new post-metamorphic populations of melanophores, xanthophores and iridophores.  相似文献   

8.
Summary Two key modifications of the previously reported method for isolation of goldfish xanthophores allowed the isolation and establishment of primary cultures of terminally differentiated melanophores from the Black Moor goldfish (Carassius auratus). First, pretreatment with 10−4 M epinephrine causing aggregation of the melanosomes and collapse of the dendrites, prevents damage to the melanophores during tissue dissociation and melanophore isolation. Second, maintenance of these cells in culture was successful only when the culture medium was supplemented with fish serum. The purified melanophores attached, flattened, and were maintained in culture for up to 3 mo. Although the morphology of the cultured melanophores is less dendritic than their in vivo counterparts, the melanophores translocate melanosomes in a normal manner except that they exhibit enhanced sensitivity to epinephrine. This epinephrine-induced pigment aggregation, as well as the redispersion of pigment after the removal of epinephrine, can occur in the presence of ethylene glycol-bis (β-aminoethyl ether)-N, N, N′, N′-tetraacetic acid and absence of Ca2+. This work was supported by grant AM13724 from the National Institutes of Health, Bethesda, MD.  相似文献   

9.
The frequencies of the polymorphic gene variants MnSOD Ala9Val, GPX1 Pro198Leu, and GSTP1 Ile105Val were estimated in female residents of Altai krai with breast cancer. The frequency distributions of the genotypes for all genes studied in both patients and control subjects fit the Hardy-Weinberg equilibrium. The estimated frequencies of the genotypes for the studied genes in the control group did not differ from those earlier reported for Caucasoid women living in Europe. The T (rs1050450) allele of the GPX1 gene was demonstrated to protect against sporadic breast cancer (OR = 0.74 (95% CI = 0.58−0.94), p = 0.012). Carriers of the genotype combination MnSOD CC + GPX1 CC were found to have a 1.6 times higher risk of sporadic breast cancer compared to the control group (OR = 1.59 (1.05−2.41), p = 0.0258). The polymorphic loci GSTP1 (rs1695) and MnSOD (rs4880) were not found to be significantly associated with the risk of familial or sporadic breast cancer.  相似文献   

10.
11.
Two unlinked autosomal recessive genes, white (d) and melanoid (m), are known to affect wild-type coloration in the axolotl. The d allele in the homozygous recessive condition reduces the total number of melanophores and restricts their migration to the top of the head and along the spinal column. The m allele in the homozygous recessive condition increases the number of melanophores and effects a more uniform distribution. The action of these genes was further investigated by studying the phenotypes of triploid larvae of known genotype at the d and m loci. Triploidy was induced by heat treating the eggs immediately after oviposition to inhibit the second maturation division. Triploidy was verified by chromosomal counts in epidermal cells of tail-tip preparations. Melanophore distribution and number were recorded at 16 and 30 days after oviposition. Two d alleles in Ddd triploids effect a reduction in melanophore number and their rate of proliferation, but have no effect on melanophore distribution. Two m alleles in Mmm triploids effect an increase in the number of melanophores and their rate of proliferation, but have no effect on their distribution. Therefore, it appears that there are at least two separate physiological actions of gene D and M, one that determines melanophore distribution and another that determines their number and rate of proliferation.  相似文献   

12.
The populations of three anuran amphibian species (Amphibia, Anura) of the genus Rana (R. ridibunda Pall., R. arvalis Nilss. and R. temporaria L.) inhabiting the Yekaterinburg urban agglomeration were examined. The frequencies of two traits, morph striata and iris depigmentation, were estimated in these populations. The former trait, so-called morph striata, is phenotypically expressed as a light dorsomedial stripe. It is controlled by a dominant allele of autosomal diallelic gene striata in some species of Rana genus, exhibiting complete dominance. Striata individuals have a number of physiological features that confer them an advantage under conditions of natural and artificial geochemical anomalies. The second trait, iris depigmentation, is the result of a recessive mutation. The individuals homozygous for this trait have low viability. Thus, the dominant mutations promote rapid adaptation of their carriers. Conversely, the recessive mutations may reduce viability of an individual.  相似文献   

13.
Polymorphism of the prolactin gene and its effect on fiber traits in goat   总被引:1,自引:0,他引:1  
The prolactin gene (PRL) is a potential candidate gene for the goat cashmere traits in markerassisted selection. Thus, the aim of this study was to detect PRL gene polymorphism and its association with fiber traits in 200 Raini cashmere goats native to the south-east of Iran. A 196-bp fragment encoding exon 5 within the goat PRL gene was amplified using PCR specific primers. The amplification products were subjected to the single stranded conformation polymorphism (SSCP) analysis. Three different SSCP banding patterns (CC, AC, and AA) were observed in exon 5 of the caprine PRL gene. The pattern frequencies for CC, AC, and AA were 0.39, 0.38, and 0.23 and frequencies of the A and C alleles were 0.42 and 0.58, respectively. The genotypic distributions did not deviate from the Hardy–Weinberg equilibrium (P > 0.05). The number of observed alleles, number of effective alleles, expected heterozygosity, observed heterozygosity, mean of heterozygosity, expected homozygosity, observed homozygosity, Nei’s index and Shanon’s index were 2.0, 1.9, 0.48, 0.38, 0.48, 0.51, 0.61, 0.48, and 0.68, respectively. Results of association between genotypes and fiber traits indicated that the CC genotype had the highest fiber length compared with the AA and AC genotypes (P > 0.05) while there was no significant association between the PRL gene genotypes and fiber diameter. These results imply that the PRL gene polymorphism can be used as a molecular marker to improve fiber production without a negative effect on fiber diameter.  相似文献   

14.
Pigment pattern variation across species or populations offers a tractable framework in which to investigate the evolution of development. Juvenile threespine sticklebacks (Gasterosteus aculeatus) from marine and freshwater environments exhibit divergent pigment patterns that are associated with ecological differences. Juvenile marine sticklebacks have a silvery appearance, whereas sticklebacks from freshwater environments exhibit a pattern of vertical bars. We investigated both the developmental and molecular basis of this population‐level variation in pigment pattern. Time course imaging during the transition from larval to juvenile stages revealed differences between marine and freshwater fish in spatial patterns of chromatophore differentiation as well as in pigment amount and dispersal. In freshwater fish, melanophores appear primarily within dark bars whereas iridophores appear within light bars. By contrast, in marine fish, these chromatophores are interspersed across the flank. In addition to spatially segregated chromatophore differentiation, pigment amount and dispersal within melanophores varies spatially across the flank of freshwater, but not marine fish. To gain insight into the molecular pathways that underlie the differences in pigment pattern development, we evaluated differential gene expression in the flanks of developing fish using high‐throughput cDNA sequencing (RNA‐seq) and quantitative PCR. We identified several genes that were differentially expressed across dark and light bars of freshwater fish, and between freshwater and marine fish. Together, these experiments begin to shed light on the process of pigment pattern evolution in sticklebacks.  相似文献   

15.
Many animals have a variety of pigment patterns, even within a species, and these patterns may be one of the driving forces of speciation. Recent molecular genetic studies on zebrafish have revealed that interaction among pigment cells plays a key role in pattern formation, but the mechanism of pattern formation is unclear. The zebrafish jaguar/obelix mutant has broader stripes than wild-type fish. In this mutant, the development of pigment cells is normal but their distribution is altered, making these fish ideal for studying the process of pigment pattern formation. Here, we utilized a positional cloning method to determine that the inwardly rectifying potassium channel 7.1 (Kir7.1) gene is responsible for pigment cell distribution among jaguar/obelix mutant fish. Furthermore, in jaguar/obelix mutant alleles, we identified amino acid changes in the conserved region of Kir7.1, each of which affected K+ channel activity as demonstrated by patch-clamp experiments. Injection of a bacterial artificial chromosome containing the wild-type Kir7.1 genomic sequence rescued the jaguar/obelix phenotype. From these results, we conclude that mutations in Kir7.1 are responsible for jaguar/obelix. We also determined that the ion channel function defect of melanophores expressing mutant Kir7.1 altered the cellular response to external signals. We discovered that mutant melanophores cannot respond correctly to the melanosome dispersion signal derived from the sympathetic neuron and that melanosome aggregation is constitutively activated. In zebrafish and medaka, it is well known that melanosome aggregation and subsequent melanophore death increase when fish are kept under constant light conditions. These observations indicate that melanophores of jaguar/obelix mutant fish have a defect in the signaling pathway downstream of the α2-adrenoceptor. Taken together, our results suggest that the cellular defect of the Kir7.1 mutation is directly responsible for the pattern change in the jaguar/obelix mutant.  相似文献   

16.
L. Reich  J. Don  R. R. Avtalion 《Genetica》1990,80(3):195-200
The inheritance of the red color was studied in two different varieties of tilapia which are both considered as hybrids of Oreochromis mossambicus. Crosses between red tilapia from the Philippines (PRT) and Sarotherodon galilaeus, or Oreochromis aureus gave a 1:1 ratio of red: normal and crosses between F1 black fish gave only black offspring. On the other hand crosses between the F1 red fish gave a 3:1 ratio of red:black and crosses between F1 red and black offspring gave a 1:1 ratio. These results lead to the conclusion that red color is dominant over the normal black color and controlled by a single autosomal gene (R). A unique phenotype named albino with black eyes was observed among offspring of PRT and a presumed model of inheritance of this trait is proposed. Genetic analysis of a second variety of red tilapia (derived from an unknown origin) showed the following results: crosses between parents and between their F1 offspring consistently gave 100% red fish and crosses between this red tilapia and Oreochromis aureus gave 100% black offspring. The crosses between red and black F1 of these last two crosses gave a 1:1 ratio and crosses carried out between the black F1 offspring gave a 1:3 ratio of red:black. It may be concluded from these results that the black color is dominant in this strain and that this color is controlled by a single autosomal gene (B). The presumed mode of action of the dominant gene (R) as well as of the recessive gene (b) are discussed.  相似文献   

17.

Background

Goldfish, Carassius auratus, have experienced strong anthropogenic selection during their evolutionary history, generating a tremendous extent of morphological variation relative to that in native Carassius. To locate the geographic origin of goldfish, we analyzed nucleotide sequences from part of the control region (CR) and the entire cytochrome b (Cytb) mitochondrial DNA genes for 234 goldfish and a large series of native specimens. Four important morphological characteristics used in goldfish taxonomy–body shape, dorsal fin, eye shape, and tailfin–were selected for hypothesis-testing to identify those that better correspond to evolutionary history.

Principal Finding

Haplotypes of goldfish rooted in two sublineages (C5 and C6), which contained the haplotypes of native C. a. auratus from southern China. Values of F ST and Nm revealed a close relationship between goldfish and native C. a. auratus from the lower Yangtze River. An extraordinary, stepwise loss of genetic diversity was detected from native fish to goldfish and from Grass-goldfish relative to other breeds. Significantly negative results for the tests of Tajima’s D and Fu and Li’s D* and F* were identified in goldfish, including the Grass breed. The results identified eye-shape as being the least informative character for grouping goldfish with respect to their evolutionary history. Fisher’s exact test identified matrilineal constraints on domestication.

Conclusions

Chinese goldfish have a matrilineal origin from native southern Chinese C. a. auratus, especially the lineages from the lower Yangtze River. Anthropogenic selection of the native Carassius eliminated aesthetically unappealing goldfish and this action appeared to be responsible for the stepwise decrease in genetic diversity of domesticated goldfish, a process similar to that reported for the domestication of pigs, rice, and maize. The three-breed taxonomy–Grass-goldfish, Egg-goldfish, and Wen-goldfish–better reflected the history of domestication.  相似文献   

18.
The medaka fish albino mutant, i1 is one of the Tomita collection of medaka pigmentation mutants which exhibits a complete albino phenotype, because of inactivation of the tyrosinase gene due to insertion of a transposable element, Tol‐1. Recently, mosaic black‐pigmented i1 medaka fish have arisen in one of our laboratory breeding populations. Their pigmented cells have been observed in all of the tissues, including the eye and skin, in which melanin is detectable in the wild type. In this study, we analyzed the tyrosinase gene of revertants and showed Tol‐1 to have been precisely excised from the gene, suggesting a causal relationship. Mosaic patterns of pigmentation indicate spontaneous somatic excision of the element from the tyrosinase gene. To our knowledge, this is the first transposable element with somatic excision activity demonstrated phenotypically in vertebrates. The pattern of pigmentation in mosaic revertants indicates frequencies of melanin pigments to be consistent with the numbers of melanophores per unit area of body sites, such as the eyes, head and dorsal trunk.  相似文献   

19.
Albinism, the loss of melanin pigmentation, has evolved in a diverse variety of cave animals but the responsible evolutionary mechanisms are unknown. In Astyanax mexicanus, which has a pigmented surface dwelling form (surface fish) and several albino cave-dwelling forms (cavefish), albinism is caused by loss of function mutations in the oca2 gene, which operates during the first step of the melanin synthesis pathway. In addition to albinism, cavefish have evolved differences in behavior, including feeding and sleep, which are under the control of the catecholamine system. The catecholamine and melanin synthesis pathways diverge after beginning with the same substrate, L-tyrosine. Here we describe a novel relationship between the catecholamine and melanin synthesis pathways in Astyanax. Our results show significant increases in L-tyrosine, dopamine, and norepinephrine in pre-feeding larvae and adult brains of Pachón cavefish relative to surface fish. In addition, norepinephrine is elevated in cavefish adult kidneys, which contain the teleost homologs of catecholamine synthesizing adrenal cells. We further show that the oca2 gene is expressed during surface fish development but is downregulated in cavefish embryos. A key finding is that knockdown of oca2 expression in surface fish embryos delays the development of pigmented melanophores and simultaneously increases L-tyrosine and dopamine. We conclude that a potential evolutionary benefit of albinism in Astyanax cavefish may be to provide surplus L-tyrosine as a precursor for the elevated catecholamine synthesis pathway, which could be important for adaptation to the challenging cave environment.  相似文献   

20.
K. A. Blagodatskikh  M. A. Evdokimova  Yu. V. Agapkina  A. G. Nikitin  A. N. Brovkin  A. A. Pushkov  E. G. Blagodatskikh  O. Yu. Kudryashova  V. S. Osmolovskaya  L. O. Minushkina  M. S. Kochkina  N. D. Selezneva  E. N. Dankovtseva  O. S. Chumakova  T. N. Baklanova  P. A. Talyzin  N. E. Reznichenko  O. P. Donetskaya  S. N. Tereshchenko  E. S. Krasil’nikova  N. A. Dzhaiani  E. V. Akatova  M. G. Glezer  A. S. Galyavich  V. B. Zakirova  N. A. Koziolova  I. V. Timofeeva  A. V. Yagoda  O. I. Boeva  L. I. Katel’nitskaya  E. V. Khorolets  S. V. Shlyk  E. G. Volkova  M. P. Margaryan  I. O. Guz’  V. O. Konstantinov  N. V. Timofeeva  B. A. Sidorenko  D. A. Zateishchikov  V. V. Nosikov 《Molecular Biology》2010,44(5):741-747
Association between the rates of poor outcomes in the patient cohort with acute coronary syndrome and polymorphisms G(?174)C in the IL6 gene and G(?1082)A in the IL10 gene were determined. In total, 1145 patients hospitalized for coronary artery disease to cardiological hospitals of Moscow, St. Petersburg, Kazan, Chelyabinsk, Perm, Stavropol, and Rostov-on-Don were examined. The mean observation period was 9.10 ± 5.03 months (maximal, 18 months). Analysis of the survival of the patients with acute coronary syndrome that carried allele A has demonstrated that the presence of IL10 gene polymorphism G(?1082)A is associated with more frequent poor outcomes as compared with GG genotype. The survival time to endpoint for the carriers of GA and AA genotypes was 11.68 ± 0.67 months versus 12.69 ± 0.65 months for the carriers of GG genotype in IL10 gene (χ2 = 4.13, p = 0.042). As for the IL6 gene polymorphism G(?174)C, survival rate analysis did not detect any significant association with the risk for poor outcome. However, joint analysis of these polymorphisms in both genes has demonstrated that characteristic of the patients with acute coronary syndrome that carry GG genotype of IL6 gene and GA and AA genotypes of IL10 is a higher rate of poor outcomes (time to endpoint, 11.01 ± 1.24 months) as compared with the carriers of IL6 gene CC and CG genotypes and IL10 gene GG genotype (time to endpoint, 13.28 ± 0.83 months (ξ2 = 10.23, p = 0.017). These data suggest that the genes IL6 and IL10, whose products are involved in the control of inflammatory response, play an important role by increasing the probability of poor outcomes in the patients with acute coronary syndrome.  相似文献   

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