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 62 毫秒
1.
Electrophoretic mobilities of three hemoglobins (Hb1, Hb2, and Hb3) were studied in 15 populations of brine shrimps. Genetic segregation data support the model that Hb2 contains n -polypeptides and n -polypeptides; Hb1 contains 2n -polypeptides. Hb3 contains neither - nor -polypeptides. There is no evidence of linkage of and loci with each other or with the locus (or loci) which governs Hb3 or with the nonhomologous portion of the sex chromosomes. Hemoglobins of different populations may be hybridized in vitro by incubation at high temperature. Reversible dissociation to subunits which contain only one ( or ) polypeptide occurs at 40 C (for Hb1) and at 50 C (for Hb2).Supported by Grant HD-11445 from the National Institutes of Health.  相似文献   

2.
The regulation of the expression of enzyme activities catalyzing initial reactions in the anoxic metabolism of various aromatic compounds was studied at the whole cell level in the denitrifying Pseudomonas strain K 172. The specific enzyme activities were determined after growth on six different aromatic substrates (phenol, 4-hydroxybenzoate, benzoate, p-cresol, phenylacetate, 4-hydroxyphenylacetate) all being proposed to be metabolized anaerobically via benzoyl-CoA. As a control cells were grown on acetate, or aerobically on benzoate. The expression of the following enzyme activities was determined.Phenol carboxylase, as studied by the isotope exchange between 14CO2 and the carboxyl group of 4-hydroxybenzoate; 4-hydroxybenzoyl-CoA reductase (dehydroxylating); p-cresol methylhydroxylase; 4-hydroxybenzyl alcohol dehydrogenase; 4-hydroxybenzaldehyde dehydrogenase; coenzymeA ligases for the aromatic acids benzoate, 4-hydroxybenzoate, phenylacetate, and 4-hydroxyphenylacetate; phenylglyoxylate: acceptor oxidoreductase and 4-hydroxyphenylglyoxylate: acceptor oxidoreductase; aromatic alcohol and aldehyde dehydrogenases.The formation of most active enzymes is strictly regulated; they were only induced when required, the basic activities being almost zero. The observed whole cell regulation pattern supports the postulate that the enzyme activities play a role in anoxic aromatic metabolism and that the compounds are degraded via the following intermediates: Phenol 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; benzoate benzoyl-CoA; p-cresol 4-hydroxybenzaldehyde 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; phenylacetate phenylacetyl-CoA phenylglyoxylate benzoyl-CoA plus CO2; 4-hydroxyphenylacetate 4-hydroxyphenylacetyl-CoA 4-hydroxyphenylglyoxylate 4-hydroxybenzoyl-CoA plus CO2 benzoyl-CoA.  相似文献   

3.
Cellulose acetate electrophoresis of mouse hemoglobins modified with the disulfide reagent cystamine permits rapid, unequivocal discrimination of all combinations of the codominant mouse hemoglobin single (Hbb s ) and diffuse (Hbb d and Hbb p ) alleles. The single, diffuse major, diffuse d-minor, and diffuse p-minor adult hemoglobins are all resolved by this method, which depends on the presence of a cysteine in the chains of diffuse mice which is not found in the chain of single mice.This work was supported by research grants ACS-VC58 and NIH CA-01074. The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care.  相似文献   

4.
We have analyzed the hemoglobins of five individual trout from the Ohrid Lake (Salmo L. typicus) by electrophoretic methods, by reversed-phase high-performance liquid chromatography, and by limited structural analyses. The two major classes of hemoglobin are type I (35% of total) and type IV (65%). Type IV is the major oxygen-transporting hemoglobin; it consists of three types of chain (in about equal quantities) and three types of chain (one major and two minor types). Several structural differences have been observed between these three (IV) chains and between the three (IV) chains, suggesting a complex genetic system governing the synthesis of these proteins. Moreover, a few amino acid substitutions occur at positions involved in contacts between chains, which suggests that differences in oxygen affinity may exist between these various type IV hemoglobins. Type I hemoglobin is less complex because it contains one type of chain and two chains; the latter two differ in numerous positions, suggesting duplications of the (I)-globin gene. The and chains of type I hemoglobin differ considerably from the and chains of type IV hemoglobin, indicating the existence of (I)- and (I)-globin genes separate from the (IV)- and (IV)- globin genes.This study was supported in part by the Yugoslav-American Joint Funds, pp 812 (to G.D.E.), and by United States Public Health Service Research Grant HLB-05168 (to T.H.J.H.).  相似文献   

5.
Summary The amino acid differences among 12 chains and 10 chains of carnivore hemoglobins are given. These hemoglobins conform to the substitution rate found for hemoglobins in general. A table compares the differences among known-chain sequences when deduced from tryptic peptide compositions and when taken from actual sequences. Among the carnivore hemoglobins studies, tryptic peptide compositions are about 14 % low in giving the number of sequence differences.  相似文献   

6.
The - and -polypeptides of LH1 isolated from four different photosynthetic bacteria (Rhodospirillum rubrum, Rhodobacter sphaeroides, Rhodobacter capsulatus and Rhodopseudomonas viridis) were used for homologous and hybrid reconstitution experiments with bacteriochlorophyll a. Formation of B820-type subunit complexes and LH1-type complexes were evaluated. The -polypeptides of R. rubrum, Rb. sphaeroides and Rb. capsulatus behaved similarly and formed B820-type subunit complexes in the absence of an -polypeptide. The - and -polypeptides were both required to form a LH1-type complex with each of these three homologous systems. In hybrid experiments where the -polypeptides were tested for reconstitution with -polypeptides other than their homologous partners, half of the twelve possible combinations resulted in formation of both B820- and LH1-type complexes. Three of the combinations that did not result in formation of a LH1-type complex involved the -polypeptide of R. rubrum. It is suggested that these latter results can be explained by charge repulsion between the Lys at position-17 (assigning the conserved His located nearest to the C-terminus as position 0) in the -polypeptide of R. rubrum and each of the heterologous -polypeptides tested, all of which have an Arg at this location. Conclusions that can be derived from these experimental results include: (1) the experimental data support the idea that a central core region of approximately 40 amino acids exists in each of the polypeptides, which contains sufficient information to allow formation of both the B820- and LH1-type complexes and (2) a specific portion of the N-terminal hydrophilic region of each polypeptide was found in which ion pairs between oppositely charged groups on the - and -polypeptides seem to stabilize complex formation.Abbreviations BChl a bacteriochlorophyll a - BChl BChl a is implied - BChl a P BChl a containing phytol as the esterifying alcohol - BChl a gg BChl a containing geranylgeraniol as the esterifying alcohol - LH1 the core light-harvesting complex - B873 the core light-harvesting complex of the G-9 mutant (carotenoidless) of R. rubrum or of the wild-type light-harvesting complex after benzene extraction (both with absorption maxima at 873 nm) - B820 the subunit form of B873 consisting of native - and -polypeptides with the same stoichiometry of 11·2BChl as LH1 - B820-type complex a complex exhibiting absorption and CD spectra indistinguishable from B820 but composed of either the -polypeptide only, or of a heterologous mixture of - and -polypeptides - RC reaction center - PRC photoreceptor complex consisting of the RC and LH1 - CD circular dichroism - OG n-octyl -d-glucopyranoside - HFA hexafluoroacetone trihydrate  相似文献   

7.
Interspecific hybridizations were carried out between the two tetraploidsElymus caucasicus andE. longearistatus, and 23 tetraploids and hexaploids ofElymus containing SH, SY, SYH, and SYW genomes and representing various geographical regions. Meiotic pairing was studied in the two target species and their hybrids. It is concluded from this study that (i) interspecific hybridization is fairly easy to perform although strong reproductive barriers exist between the species; (ii)Elymus caucasicus andE. longearistatus are allotetraploids, and share the diverged SY genomes; (iii) the divergence of SY genomes is correlated with the geographic distance between theElymus spp. studied.  相似文献   

8.
The production of five chain variants (Hb G-Georgia, Hb St. Luke's, Hb Lloyd, Hb Montgomery, and Hb G-Philadelphia) in heterozygotes was evaluated through hematological observations, hemoglobin quantification, and biosynthetic studies. All heterozygotes for Hb St. Luke's and Hb Lloyd and most heterozygotes with Hb G-Georgia and Hb Montgomery had normal hematology and average / values of about 1.1. They were assigned a normal genotype (G/), although the proportions of Hb St. Luke's and Hb G-Georgia were low (10 to 13%) and those of Hb Lloyd and Hb Montgomery twice as high (20%). Data from short-term incubations confirmed this genotype for some of these heterozygotes. Isolated Hb St. Luke's and Hb G-Georgia gave low G/ values (0.2 and 0.3) indicating that these Hb variants were defective at the level of Hb assembly. Isolated Hb Montgomery and Hb G-Philadelphia, however, gave higher G/ values of 0.6 and 0.8, respectively. A second type of variability existed among Hb G-Georgia (20 vs. 13%), Hb Montgomery (28 vs. 20%), and Hb G-Philadelphia (47 vs. 34%) heterozygotes, in whom the levels of Hb G differed. The occurrence of higher levels of these three chain heterozygosities was associated with hematological or biosynthetic evidence of a mild or moderate chain deficiency due to an -thalassemia-2 heterozygosity (G/0 or 0G/) or a homozygosity (0G/0), respectively.This study was supported in part by USPHS Research Grants HLB-05168 and HLB-15158.  相似文献   

9.
Summary White and intermediate parietal muscle fibers of Myxine are innervated focally at one end. Most synaptic vesicles are empty. These terminals also contain 1–2% large 800–1.100 Å dense-core vesicles. Red fibers of parietal and craniovelar muscle are innervated in a distributed fashion, and the presynaptic profiles contain a higher number of large dense-core vesicles (averaging 9% and 15%, respectively; up to 37%). For all terminals the synaptic gap is 450–600 Å wide, and postsynaptic folds are absent.Empty synaptic vesicles exist as round or elongated profiles. The proportion of elongated profiles increases by formation from round ones when increasing the molarity of the buffer in the aldehyde fixative. Furthermore, the proportion of elongated vesicle profiles in terminals on Myxine white fibers at different buffer molarities, is identical with that in mammalian motor terminals at similar molarities. On this basis the significance and mode of formation of elongated vesicle profiles is discussed. The conclusion is made that the susceptibility of flattening depends on the osmotic pressure of the vesicle contents once the aldehyde has influenced the vesicle membrane.The different vesicle populations in terminals on different types of muscle fibers are significant. Terminals on red fibers probably contain serotonin (5-HT) either as sole transmitter or in addition to acetylcholine.The author is indebted to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supply of hagfishes, and to Mrs. Jorunn Line Vaaland for expert technical assistance.  相似文献   

10.
Tsuno  Kendo  Aotsuka  N. T.  Ohba  Shigeru 《Biochemical genetics》1984,22(3-4):323-337
Reexamination of the electrophoretic mobilities of esterases encoded by the Est- and the Est- alleles of Drosophila virilis was carried out in detail using both thin-layer agar gel and polyacrylamide slab gel electrophoresis. Many allelic products with fine differences in their electrophoretic mobilities were found and designated by a new system. Some esterases separable by the agar gel method were indistinguishable using the polyacrylamide gel method. But the polyacrylamide gel method uncovered two multiband homozygotes, (d).77 and (d)1.28. Some allelic frequencies on the basis of the new designation were estimated in two natural populations. As a result, it is proposed that the total scope of allelic variation at the two esterase loci of Drosophila virilis is composed of discrete distribution patterns of gene frequencies, each histogram of which shows a bell-shaped pattern.  相似文献   

11.
The control regions of mitochondrial DNA of two insects, Schistocerca gregaria and Chorthippus parallelus, have been isolated and sequenced. Their sizes are 752 by and 1,512 bp, respectively, with the presence of a tandem repeat in C. parallelus. (The sequences of the two repeats are highly conserved, having a homology of 97.5%.) Comparison of their nucleotide sequences revealed the presence of several conserved sequence blocks dispersed through the whole control region, showing a different evolutionary pattern of this region in these insects as compared to that in Drosophila. A highly conserved secondary structure, located in the 3 region near the small rRNA gene, has been identified. Sequences immediately flanking this hairpin structure rather than the sequences of this structure themselves are conserved between S. gregaria/C. parallelus and Drosophila, having a sequence consensus of TATA at 5 and GAA(A)T at 3. The motif G(A)nT is also present in the 3 flanking sequences of mammalian, amphibian, and fish mitochondrial L-strand replication origins and a potential plant mitochondrial second-strand-replication origin, indicating its universal conservation and functional importance related to replication origins. The stem-and-loop structure in S. gregaria/C. parallelus appears to be closely related to that found in Drosophila despite occupying a different position, and may be potentially associated with a second-strand-replication origin. This in turn suggests that such a secondary structure might be widely conserved across invertebrates while their location in the control region may be variable. We have looked for such a conserved structure in the control regions of two other insects, G. firmus and A. mellifera, whose DNA sequences have been published, and their possible presence is discussed.Mitochondrial control regions characterized to date in five different insect taxa (Drosophila, G. firmus, A. mellifera, S. gregaria, and C. parallelus) may be classed into two distinct groups having different evolutionary patterns. It is observed that tandem repetition of regions containing a probable replication origin occurred in some species from disjunct lineages in both groups, which would be the result of convergent evolution. We also discuss the possibility of a mechanism of parahomologous recombination by unequal crossing-over in mitochondria, which can explain the generation of such tandemly repeated sequences (especially the first critical repetition) in the control region of mtDNA, and also their convergent evolution in disjunct biological lineages during evolution. Correspondence to: G.M. Hewitt  相似文献   

12.
Clostridium sporogenes MD1 grew rapidly with peptides and amino acids as an energy source at pH 6.7. However, the proton motive force (p) was only –25 mV, and protonophores did not inhibit growth. When extracellular pH was decreased with HCl, the chemical gradient of protons (ZpH) and the electrical membrane potential () increased. The p was –125 mV at pH 4.7, even though growth was not observed. At pH 6.7, glucose addition did not cause an increase in growth rate, but increased to –70 mV. Protein synthesis inhibitors also significantly increased . Non-growing, arginine-energized cells had a of –80 mV at pH 6.7 or pH 4.7, but was not detected if the F1F0 ATPase was inhibited. Arginine-energized cells initiated growth if other amino acids were added at pH 6.7, and and ATP declined. At pH 4.7, ATP production remained high. However, growth could not be initiated, and neither nor the intracellular ATP concentration declined. Based on these results, it appears that C. sporogenes MD1 does not need a large p to grow, and p appears to serve as a mechanism of ATP dissipation or energy spilling.Mandatory disclaimer: Proprietary or brand names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product, and exclusion of others that may be suitable.  相似文献   

13.
Summary The amino acid compositions of the tryptic peptides of the following carnivore hemoglobin chains have been determined: gray fox (Urocyon cineroargenteus); raccoon (Procyon lotor); polar bear (Thalarctos maritimus); coati mundi (Nasua nasua) chain; coati mundi (Nasua narica) two chains; cat (Felis catus) chain; and lion (Panthera leo) chain. These provide a basis for future sequencing of these hemoglobins and construction of an evolutionary tree. The specific results are summarized in the following article (Stenzel and Brimhall, 1977).  相似文献   

14.
The study deals with a comparative analysis of the relative abundances of the carbon isotopes 12C and 13C in the metabolites and biomass of the Burkholderia sp. BS3702 and Pseudomonas putida BS202-p strains capable of utilizing aliphatic (n-hexadecane) and aromatic (naphthalene) hydrocarbons as sources of carbon and energy. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of Burkholderia sp. BS3702 on n-hexadecane (13C = –44.6 ± 0.2) were characterized by the values of 13CCO 2 = –50.2 ± 0.4, 13Cbiom = –46.6 ± 0.4, and 13Cexo = –41.5 ± 0.4, respectively. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of the same bacterial strain on naphthalene (13C = –21 ± 0.4) were characterized by the isotope effects 13CCO 2 = –24.1 ± 0.4, 13Cbiom = –19.2 ± 0.4, and 13Cexo = –19.1 ± 0.4, respectively. The possibility of using the isotope composition of metabolic carbon dioxide for the rapid monitoring of the microbial degradation of petroleum hydrocarbons in the environment is discussed.  相似文献   

15.
Summary The inheritance of resistance to brown planthopper, Nilaparvata lugens (Stol.), of 20 rice cultivars was studied. Single dominant genes that are allelic to Bph 3 condition the resistance in cultivars Ptb 19, Gangala (Acc. 7733), Gangala (Acc. 15207), Horana Mawee, Kuruhondarwala, Mudu Kiriyal and Muthumanikam. Single recessive genes that are allelic to bph 4 govern the resistance in cultivars Gambada Samba, Heenhoranamawee, Hotel Samba, Kahata Samba, Kalukuruwee, Lekam Samba, Senawee, Sulai, Thirissa and Vellai Illankali. The resistance in Ptb 33, Sudu Hondarwala, and Sinna Sivappu is governed by one dominant and one recessive gene which segregate independently of each other. The dominant resistance genes in these cultivars appear allelic to either Bph 1 or Bph 3. Similarly, the recessive genes in these cultivars seem allelic to either bph 2 or bph 4. Further investigations are needed to conclusively determine the allelic relationships of resistance genes in Ptb 33, Sudu Hondarwala and Sinna Sivappu.  相似文献   

16.
Summary Corticotropin and melanotropin producing cells were localized in the adenohypophysis of normal Lerots by using antibodies against synthetic corticotropins (anti 1–24 ACTH, anti 17–39 ACTH, anti 25–39 ACTH), and melanotropins (anti MSH, anti MSH). All the anticorticotropin sera stained the same cells both in the anterior lobe and in the intermediate lobe. The anti MSH serum only stained a few cells, exclusively located in the intermediate lobe. These MSH cells were not stained with anticorticotropin antibodies. The anti MSH serum revealed all the cells stained with anticorticotropin and anti MSH sera. Absorption tests showed that the 4–10 heptapeptide common to ACTH and MSH, is not responsible for the immunohistochemical staining. The staining of only some corticotrophs with the anti 4–10 ACTH serum might indicate the presence in these cells of a peptide with an accessible 4–10 site. These results are discussedWe thank A. Pillez for technical assistance (C.N.R.S.). This work was supported by a grant from U.E.R. III Lille 1976Attaché de Recherche INSERM  相似文献   

17.
Four bread wheat (Triticum aestivum L.) cultivars, Aobakomugi, Chinese Spring, Norin 61 and Shinchunaga, were pollinated with five barley lines/cultivars consisting of three cultivated barley (Hordeum vulgare L.) lines, Betzes, Kinai 5 and OHL089, and two wild barley (Hordeum spontaneum C. Koch) lines, OUH602 and OUH324. Crossability, expressed as the percentage of embryo formation, varied from 0 to 55.4% among the cross combinations. The two wild barley lines generally had a higher crossability than the previously reported best pollinator, Betzes, and some Japanese wheat cultivars were better as the female parent than Chinese Spring. Ninety four hybrid plants were obtained from 250 embryos cultured, and their somatic chromosome numbers ranged from 21 to 36. Eighteen plants were mosaic in chromosome number. Twenty one-chromosome plants appeared most frequently (45.7%) followed by 28-chromosome plants (14.9%). C-banding analysis revealed that elimination of barley chromosomes was mainly responsible for the occurrence of aneuploid plants. In hypoploids derived from Betzes-crosses, chromosome 5 was preferentially eliminated as previously reported, while in hypoploids derived from OUH602-crosses, chromosome 4 was preferentially eliminated. The wild barley line OUH602 may be a useful parent for producing a new wheat-barley addition set because of its high crossability with wheat and a different pattern of chromosome elimination.  相似文献   

18.
Morniga M is a jacalin-related and mannose-specific lectin isolated from the bark of the mulberry (Morus nigra). In order to understand the function and application of this novel lectin, the binding property of Morniga M was studied in detail using an enzyme-linked lectinosorbent assay and lectin-glycan inhibition assay with extended glycan/ligand collection. From the results, it was found that the di-, tri-, and oligomannosyl structural units of N-glycans such as those of the bovine 1-acid glycoprotein (gp) and lactoferrin were the most active gps, but not the O-glycans or polysaccharides including mannan from yeast. The binding affinity of Morniga M for ligands can be ranked in decreasing order as follows: gps carrying multiple N-glycans with oligomannosyl residues >> N-glycopeptide with a single trimannosyl core > Tri-Man oligomer [Man1 6(Man 1 3) Man], Penta-Man oligomer [Man1 6(Man1 3)Man1 6(Man1 3) Man] Man 1 2, 3 or 6 Man > Man > GlcNAc, Glc >> L-Fuc, Gal, GalNAc (inactive), demonstrating the unique specificity of this lectin that may not only assist in our understanding of cell surface carbohydrate ligand-lectin recognition, but also provide informative guidelines for the application of this structural probe in biotechnological and clinical regimens, especially in the detection and purification of N-linked glycans.  相似文献   

19.
    
UDP-GlcNAc:Man1-3R 1-2-N-acetylglucosaminyltransferase I (GlcNAc-T I; EC 2.4.1.101) catalyses the conversion of [Man1-6(Man1-3)Man1-6][Man1-3]Man-O-R to [Man1-6(Man1-3)Man1-6] [GlcNAc1-2Man1-3]Man-O-R (R=1-4GlcNAc1-4GlcNAc-Asn-X) and thereby controls the conversion of oligomannose to complex and hybrid asparagine-linked glycans (N-glycans). GlcNAc-T I also catalyses the conversion of Man1-6(Man1-3)Man-O-octyl to Man1-6(GlcNAc1-2Man1-3)Man-O-octyl. We have therefore tested a series of synthetic analogues of Man1-6(Man1-3)Man-O-octyl as substrates and inhibitors for rat liver GlcNAc-T I. The 2-deoxy and the 3-, 4- and 6-O-methyl derivatives are all good substrates confirming previous observations that the hydroxyl groups of the Man1-6 residue do not play major roles in the binding of substrate to enzyme. In contrast, all four hydroxyl groups on the Man1-3 residue are essential since the corresponding deoxy derivatives either do not bind (2- and 3-deoxy) or bind very poorly (4- and 6-deoxy) to the enzyme. The 2- and 3-O-methyl derivatives also do not bind to the enzyme. However, the 4-O-methyl derivative is a substrate (K m =2.6mm) and the 6-O-methyl compound is a competitive inhibitor (K i=0.76mm). We have therefore synthesized various 4- and 6-O-alkyl derivatives, some with reactive groups attached to anO-pentyl spacer, and tested these compounds as reversible and irreversible inhibitors of GlcNAc-T I. The 6-O-(5-iodoacetamido-pentyl) compound is a specific time dependent inhibitor of the enzyme. Four other 6-O-alkyl compounds showed competitive inhibition while the remaining compounds showed little or no binding indicating that the electronic properties of the attachedO-pentyl groups influence binding.Abbreviations GlcNAc-T I UDP-GlcNAc:Man1-3R 1-2-N-acetylglucosaminyltransferase I (EC 2.4.1.101) - GlcNAc-T II UDP-GlcNAc:Man1-6R 1-2-N-acetylglucosaminyltransferase II (EC 2.4.1.143) - MES 2-(N-morpholino)ethane sulfonic acid monohydrate  相似文献   

20.
Transmannosylation from mannotriose (Man1-4Man1-4Man) to the 4-position at the nonreducing end N-acetylglucosaminyl residue ofN,N-diacetylchitobiose was regioselectively induced through the use of -d-mannanase fromAspergillus niger. The enzyme formed the trisaccharide Man1-4GlcNAc1-4GlcNAc (3.7% of the enzyme-catalysed net decrease ofN,N-diacetylchitobiose) from mannotriose as a donor andN,N-diacetylchitobiose as an acceptor. Mannobiose (Man1-4Man) was also shown to be useful as a donor substrate for the desired trisaccharide synthesis.Abbreviations Man d-mannose - (M n) (n=1–5) -linkedn-mer of mannose - GlcNAc2 2-acetamido-2-deoxy--d-glucopyranosyl-(1–4)-2-acetamido-2-deoxy-d-glucose  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