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Results for “Hybridization”

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At least 253 records · Page 14Linked to original sources

PubMed1994

Isolation of intergeneric hybrids between Bacillus subtilis and Zymomonas mobilis and the production of thermostable amylase by hybrids.

Stable hybrids were obtained by protoplast fusion between Bacillus subtilis and Zymomonas mobilis. All the hybrids were able to hydrolyse starch and possessed ampicillin- and tetracycline-resistant phenotypes. Two of the hybrids, BZ-1 and BZ-2, were hyperproducers of alpha-amylase. The enzyme produced by these hybrids exhibited increased thermostability. The results show that stable intergeneric gene transfer can be achieved through poly(ethylene glycol)-mediated protoplast fusion between two industrially important genera of bacteria.

Bacillus subtilis↗

PubMed1996

Human endogenous retroviral element k10 (HERV-K10): chromosomal localization by somatic hybrid mapping and fluorescence in situ hybridization.

The human endogenous retrovirus K10 (HERV-K10) was mapped to human chromosomes using HERV-K10 specific PCR primers on a somatic hybrid mapping panel. A non-random chromosomal location was demonstrated with PCR signals on chromosomes 1, 3, 4, 5, 6, 7, 10, 11, 12, 14, 15, 19, 20, 21, 22 and Y. There was a lack of PCR products on the other chromosomes, even after hybridization with a HERV-K10 specific probe. To further localize the HERV-K10 sequence we used fluorescence in situ hybridization. Chromosomes 1, 3, 6, 7, 10, 11, 12 and 22 were found to contain several HERV-K10 sequences in different regions. The presence of several integration sites on some chromosomes is consistent with previous studies demonstrating 30-50 copies of the HERV-K10 sequence per haploid genome. The mapping information reported in this study will assist the analysis of the biological significance of the HERV-K10 sequence.

Base Sequence↗

PubMed1987

Increased therapeutic effect of vinca alkaloids targeted to tumour by a hybrid-hybrid monoclonal antibody.

Unmodified vinblastine (VLB) targeted through one of the antigen combining sites of the hybrid-hybrid 28.19.8 monoclonal is potentially more effective in suppressing the growth of established MAWI tumour xenografts implanted on nude mice than free VLB in the absence of the targeting agent, presumably due to an increased local drug concentration. Our efficacy results in this study suggest that drug, specifically removed from the circulation by hybrid-hybrid antibody previously located to the tumour mass, can be made available in a pharmacologically active from. Histological analysis of the treated tumours revealed dramatic changes in the tumour organisation with only a few surviving tumour cells with altered morphology.

Animals↗

PubMed1977

Genetic studies of hybrids between coliphage lambda and salmonella phage P22: genetic analysis of the P22-lambda hybrid class.

P22-lambda hybrids which retain the protein coat of P22 have been isolated and characterized into two types. Type 1 hybrids which have the c through O-P genes of lambda are unable to grow lytically on Salmonella typhimurium. On the other hand, type 2 hybrids which contain only the c region of lambda, plated on S. typhimurium. Both hybrid types retained the generalized transducing and antigenic conversion capabilities of P22.

Antigens, Viral↗

PubMed2002

Hybridization between European and Asian dandelions ( Taraxacum section Ruderalia and section Mongolica)2. Natural hybrids in Japan detected by chloroplast DNA marker.

Natural hybridization in Taraxacum between native sexual diploids and introduced agamospermous triploids occurring in Japan was studied by means of chloroplast DNA (cpDNA) marker. We first determined the nucleotide sequences between trnT (UGU) and trnF (GAA) of cpDNA for 22 plants obtained from Japan and Europe. The sequences analyzed were about 1,574 base pairs long. Among all accessions, the total numbers of polymorphic characters were 56 nucleotide substitutions, three insertions/deletions (ins/dels), and one repeat number polymorphism of mononucleotide motif. Of these polymorphic characters, four nucleotides and one ins/del were applicable in the discrimination between Japanese and European taxa of dandelions. We selected the ins/del in an intergenic region between trnL (UAA) 3' exon and trnF (GAA) as a cpDNA marker. Using a newly developed cpDNA marker, 225 plants of putative Taraxacum officinale collected from 11 populations in Niigata City were investigated. Eighty-two percent of them showed a Japanese haplotype of cpDNA, and they were regarded as hybrids. Compared with the previous studies, it is likely that the prevalence of the hybrid plants is a general phenomena at least in urban areas in Japan. The validity of the cpDNA marker for screening Taraxacum hybrids is discussed.

Journal Article↗

PubMed1987

Specific suppression of the in vitro parent anti-hybrid reaction. II. Parameters influencing suppressor cell induction in the F1 hybrid.

In the accompanying paper (K. Kosmatopoulos et al., Cell. Immunol. 104, 319-334, 1987) we have reported that the spleens of B6D2F1 hybrids pretreated with B6 spleen cells 7 days earlier contain a cell which specifically suppresses the in vitro proliferative and cytotoxic B6 anti-B6D2F1 responses. The results we present here concern the in vivo conditions under which this suppressor cell can be induced. Suppressor cell activity appears early after the injection of B6 spleen cells (day +1), increases on Day 7, and disappears by Day 30; it is always detectable after the injection of 5 X 10(7) B6 spleen cells and never after the injection of 1.25 X 10(7) cells, the intermediate dose of 2.5 X 10(7) cells being followed by variable results. This variability is attributable to the age of B6 donor and B6D2F1 recipient mice, and suppression is never observed when 2.5 X 10(7) spleen cells from 6-week-old B6 mice are injected into 6-week-old B6D2F1 hybrids. The suppressor cell is induced by the injection of B6 spleen cells of the Thy-1+ Ly-1-2+ phenotype, even if they are irradiated at 1000 R just before their injection. Lymph node cells from B6 mice induce the suppressor cell, whereas thymocytes do not. Irradiation of B6D2F1 hybrids at 600 or 950 R does not prevent the induction of suppressor cell, nor does thymectomy. Moreover, in the thymectomized or 600 R-irradiated B6D2F1 animals suppression can be induced even by the injection of only 1.25 X 10(7) B6 spleen cells. This phenomenon of specific suppression is not limited to the B6-B6D2F1 genetic combination since it has been observed in all parent-hybrid combinations tested to date.

Animals↗

PubMed1991

Mycoplasma gallisepticum strain S6 genome contains three regions hybridizing with 16 S rRNA and two regions hybridizing with 23 S and 5 S rRNA.

Southern hybridization and cloning experiments revealed existence of 3 regions hybridizing with 16 S rRNA and 2 regions hybridizing with 23 S and 5 S rRNA in Mycoplasma Gallisepticum strain S6 genome thus forming 4 separate contiguous regions. One set of a putative rRNA genes is organized classically for eubacteria order 16 S-23 S-5 S. The other two 16 S rRNA and the other one 23 S-5 S rRNA hybridizing regions are separated from each other and from the complete rRNA operon for a distance of more than 6 kb.

Base Sequence↗

PubMed1997

Solution structure of an RNA.2'-O-methylated RNA hybrid duplex containing an RNA.DNA hybrid segment at the center.

The solution structure of an RNA.2'-O-methylated RNA hybrid duplex containing an RNA.DNA hybrid segment at its center, (ggagaugac).(GmUmCmATCTCmCm), where lowercase letters, capital letters, and capital letters with the subscript m are RNA, DNA, and 2'-O-methylated RNA residues, respectively, was determined by observing the NMR spectra and performing the full relaxation matrix refinement. The 2'-O-methylation gives several characteristic features to oligoribonucleotides. In addition, this hybrid duplex is cleaved at a specific position by Escherichia coli ribonuclease HI, and so the role of the tertiary structure during the substrate recognition by the enzyme is of interest. The NOE connectivities among the proton resonances revealed that the duplex was a right handed helix. The 2'-O-methylated RNA segments had a typical C3'-endo conformation, and the 2'-O-methyl groups were directed to the minor groove of this duplex, taking the torsion angles phi (C1'-C2'-02'-CH3) that were all gauche(+). The DNA residues in the central RNA.DNA hybrid duplex formed the C3'-endo conformation, except for the middle thymine residue. No remarkable structural discontinuities were observed around the junction sites at either the 5'- or 3'-end of the DNA. The overall structure was close to the typical A-form duplex.

Crystallography, X-Ray↗

PubMed2005

Organic-inorganic hybrid liquid crystals: thermotropic mesophases formed by hybridization of liquid-crystalline phosphates and monodispersed alpha-Fe2O3 particles.

A novel organic-inorganic hybrid thermotropic liquid crystal (LC) is developed by the hybridization of an organic phosphate having a mesogenic core and monodispersed alpha-Fe2O3 particles with different shapes through the specific adsorption of the phosphate group to the surfaces parallel to the c-axis of the alpha-Fe2O3. The hybrid LC shows thermotropic nematic or cubic liquid-crystallinity in wide ranges of temperatures. Variable-temperature small-angle X-ray measurements reveal that the spontaneous formation of periodic structure by the hybridization induces the thermotropic liquid crystallinity. This technique would lead development of novel types of dynamic functional materials with multi-responsiveness to magnetic and electric fields.

Crystallization↗

PubMed2005

Databases for transition element bonding: metal-metal bond energies and bond lengths and their use to test hybrid, hybrid meta, and meta density functionals and generalized gradient approximations.

We propose a data set of bond lengths for 8 selected transition metal dimers (Ag(2), Cr(2), Cu(2), CuAg, Mo(2), Ni(2), V(2), and Zr(2)) and another data set containing their atomization energies and the atomization energy of ZrV, and we use these for testing density functional theory. The molecules chosen for the test sets were selected on the basis of the expected reliability of the data and their ability to constitute a diverse and representative set of transition element bond types while the data sets are kept small enough to allow for efficient testing of a large number of computational methods against a very reliable subset of experimental data. In this paper we test 42 different functionals: 2 local spin density approximation (LSDA) functionals, 12 generalized gradient approximation (GGA) methods, 13 hybrid GGAs, 7 meta GGA methods, and 8 hybrid meta GGAs. We find that GGA density functionals are more accurate for the atomization energies of pure transition metal systems than are their meta, hybrid, or hybrid meta analogues. We find that the errors for atomization energies and bond lengths are not as large if we limit ourselves to dimers with small amounts of multireference character. We also demonstrate the effects of increasing the fraction of Hartree-Fock exchange in multireference systems by computing the potential energy curve for Cr(2) and Mo(2) with several functionals. We also find that BLYP is the most accurate functional for bond energies and is reasonably accurate for bond lengths. The methods that work well for transition metal bonds are found to be quite different from those that work well for organic and other main group chemistry.

Journal Article↗

PubMed1999

Hybrid-hybrid matrix structural refinement of a DNA three-way junction from 3D NOESY-NOESY.

Homonuclear 3D NOESY-NOESY has shown great promise for the structural refinement of large biomolecules. A computationally efficient hybrid-hybrid relaxation matrix refinement methodology, using 3D NOESY-NOESY data, was used to refine the structure of a DNA three-way junction having two unpaired bases at the branch point of the junction. The NMR data and the relaxation matrix refinement confirm that the DNA three-way junction exists in a folded conformation with two of the helical stems stacked upon each other. The third unstacked stem extends away from the junction, forming an acute angle (approximately 60 degrees) with the stacked stems. The two unpaired bases are stacked upon each other and are exposed to the solvent. Helical parameters for the bases in all three strands show slight deviations from typical values expected for right-handed B-form DNA. Inter-nucleotide imino-imino NOEs between the bases at the branch point of the junction show that the junction region is well defined. The helical stems show mobility (+/- 20 degrees) indicating dynamic processes around the junction region. The unstacked helical stem adjacent to the unpaired bases shows greater mobility compared to the other two stems. The results from this study indicate that the 3D hybrid-hybrid matrix MORASS refinement methodology, by combining the spectral dispersion of 3D NOESY-NOESY and the computational efficiency of 2D refinement programs, provides an accurate and robust means for structure determination of large biomolecules. Our results also indicate that the 3D MORASS method gives higher quality structures compared to the 2D complete relaxation matrix refinement method.

Base Pairing↗

PubMed2001

Ilizarov hybrid external fixation for fractures of the distal radius: Part II. Internal fixation versus Ilizarov hybrid external fixation: Stability as assessed by cadaveric simulated motion testing.

The in vitro stability of an Ilizarov hybrid external fixator was compared with that of a dorsal 3.5-mm AO T-plate in 8 unpaired, fresh-frozen upper extremities. A specially designed testing device that used computer-controlled pneumatic actuators was used to simulate active finger, wrist, and forearm motions by applying loads to relevant tendons. A comminuted extra-articular distal radius fracture was modelled using a dorsally based wedge osteotomy. Fracture stability was assessed using an electromagnetic tracking device to measure motion across the fracture site after randomized application of the plate and the hybrid fixator. During simulated finger and wrist motions with the forearm pronated or supinated, motion of the distal fragment with the hybrid fixator applied was comparable to or statistically less than with the AO plate applied. During simulated forearm rotation, the stability provided by the 2 fixation types was similar, although the plate allowed statistically less radial-ulnar deviation of the fragment. In this model of a 2-part extra-articular distal radius fracture, the clinically meaningful stability of the Ilizarov hybrid external fixator was comparable to that of the dorsal AO plate.

Aged↗

PubMed2003

Activity of hybrid type I interferons in cells lacking Tyk2: a common region of IFN-alpha 8 induces a response, but IFN-alpha2/8 hybrids can behave like IFN-beta.

Type I interferons (IFNs) are a family of pleiotropic cytokines with antiviral, antiproliferative, and immunomodulatory properties. The type I IFN family consists of 12 IFN-alpha subtypes, IFN-beta, and IFN-omega. Cells lacking the receptor-associated protein kinase Tyk2 (U1A) are responsive only to IFN-beta and partially to IFN-alpha8. We constructed a series of IFN-alpha2/alpha8 hybrids and mutants and identified the region within IFN-alpha8 responsible for its activity in Tyk2-deficient cells. The same domain mediates the interactions between IFN and IFN-alpha receptor (IFNAR) in Tyk2-complemented and Tyk2-deficient cells (U1A). The presence or absence of Tyk2 altered the inhibitory effects of anti-IFNAR antibodies, suggesting that the IFN-alpha binding domain on IFNAR is altered by the presence of Tyk2. The activity of IFN-beta was not significantly affected by the deletion of Tyk2, and, surprisingly, one of our IFN-alpha2/alpha8 hybrids (IFN-alpha288) behaved like IFN-beta in a number of assays that distinguish IFN-alphas from IFN-beta. This suggests that this hybrid mimics the interactions of IFN-beta with the receptor and also suggests the existence of a distinct binding site(s) on IFNAR for IFN-beta and some hybrid IFN-alphas.

Amino Acid Sequence↗

PubMed2006

Tests of rRNA hybridization to microarrays suggest that hybridization characteristics of oligonucleotide probes for species discrimination cannot be predicted.

Hybridization of rRNAs to microarrays is a promising approach for prokaryotic and eukaryotic species identification. Typically, the amount of bound target is measured by fluorescent intensity and it is assumed that the signal intensity is directly related to the target concentration. Using thirteen different eukaryotic LSU rRNA target sequences and 7693 short perfect match oligonucleotide probes, we have assessed current approaches for predicting signal intensities by comparing Gibbs free energy (DeltaG degrees) calculations to experimental results. Our evaluation revealed a poor statistical relationship between predicted and actual intensities. Although signal intensities for a given target varied up to 70-fold, none of the predictors were able to fully explain this variation. Also, no combination of different free energy terms, as assessed by principal component and neural network analyses, provided a reliable predictor of hybridization efficiency. We also examined the effects of single-base pair mismatch (MM) (all possible types and positions) on signal intensities of duplexes. We found that the MM effects differ from those that were predicted from solution-based hybridizations. These results recommend against the application of probe design software tools that use thermodynamic parameters to assess probe quality for species identification. Our results imply that the thermodynamic properties of oligonucleotide hybridization are by far not yet understood.

Animals↗

PubMed1980

Methylamine dehydrogenases of Methylomonas J and Pseudomonas AM1. Hybridization of light and heavy subunits and some properties of an isolated hybrid enzyme.

Hybridization reactions were carried out in vitro between the light and heavy subunits of two methylamine dehydrogenases obtained from Methylomonas J (formerly Pseudomonas sp. J) and Pseudomonas AM1. Enzymatic activity was restored with a combination of L3(MW: 13,000) and HA(MW: 40,000) but not with LA(MW: 13,000) and HJ(NW: 40,000). This active hybrid enzyme was isolated with a Sephadex G-150 column after incubation of LJ and HA. Its molecular weight was nearly identical to that of the two native enzymes (MW: 105,000). The electrophoretic pattern of proteins cross-linked by dimethyl suberimidate showed the formation of a tetrameric structure. Its absorption spectrum was similar to that of the native enzymes. The specific activity was 4.3 and the substrate specificity resembled that of the Methylomonas J enzyme rather than that of the Pseudomonas AM1 enzyme. Michaelis constants were 290 microM for methylamine and 14 microM for phenazine methosulfate. The circular dichroism spectrum and thermal stability resembled those of the Pseudomonas AM1 enzyme. No appreciable amount of an inactive hybrid enzyme was formed in the reaction between LA and HJ, there being neither restoration of the enzymatic activity nor formation of cross-linked tetrameric proteins with dimethyl suberimidate. Hybridization of LJ and HA was further confirmed by the appearance of three enzymatic active bands on a gel after electrophoresis of an incubation mixture of LJ, HJ, and HA. The results are consistent with a previous observation; the two methylamine dehydrogenases from either obligate of facultative metaylotrophs are the alpha 2 beta 2-type and homologous enzymes. It is also suggested that substrate specificity and catalytic activity are directed by the light subunit, and binding affinity of the substrate to the active site, electrophoretic mobility, and thermal stability of the enzyme are endowed by the heavy subunit.

Kinetics↗

PubMedDate not supplied

Hybrid gene or hybrid steroids in the detection and screening for familial hyperaldosteronism type I.

1. Early diagnosis of Familial Hyperaldosteronism Type I (FH-I, glucocorticoid-suppressible hyperaldosteronism) in asymptomatic, affected individuals is essential if death from stroke is to be prevented. 2. In 21 patients with FH-I (presence of the causative hybrid 11 beta-hydroxylase/aldosterone synthase gene confirmed by Southern blot testing), various biochemical parameters were compared as possible screening tests. Hypokalaemia and elevated plasma aldosterone each detected only two (10%) of the affected individuals. 3. Plasma renin activity 19 (90%) and aldosterone/renin ratio 18 (86%) were more reliable but not free from false negatives. 4. Levels of the urinary 'hybrid' steroid, 18-oxocortisol, were elevated (P < 0.01) in all 15 patients tested (138.2 +/- 17.4 micrograms/g creatinine, range 41.6 +/- 281.0 micrograms/g) with no overlap when compared with 11 normals (9.7 +/- 1.3 micrograms/g, range 2.8-17.4 micrograms/g). 5. We conclude that measurement of urinary 'hybrid' steroids is probably the most rapid and reliable biochemical screening test currently available for FH-I, with confirmation dependent on demonstration of the hybrid gene by genetic techniques.

Adult↗

PubMed1991

Generation of hybrid hybridomas secreting human IgM class hybrid antiricin and antidiphtheria toxin antibodies.

Two lines of mouse-human hybridomas were fused to produce human bifunctional antibodies. A hybridoma that secretes human IgM (kappa) class antiricin monoclonal antibody was treated with actinomycin D to inhibit cell growth. Another cell line, secreting human IgM (lambda) class antidiphtheria toxin monoclonal antibody, was 6-thioguanine resistant (HAT sensitive). Six hybridomas secreting IgM with both kappa and lambda light chains were obtained. Two of them secreted antibodies with antiricin specificity (kappa and lambda light chains) and antidiphtheria toxin specificity (kappa and lambda light chains). Antidiphtheria toxin antibodies secreted from other hybrid hybridomas did not contain kappa light chain, but lambda chain. A hybrid hybridoma clone 5-29 secreted complete hybrid IgM with lowered affinity to diphtheria toxin. These results suggested unbalanced recombination of immunoglobulin polypeptide chains in hybrid hybridomas.

Animals↗

PubMed1989

The F1 hybrid effect in allogeneic lymphocyte cytotoxicity. Points of similarity between hybrid resistance and ALC.

Allogeneic lymphocyte cytotoxicity (ALC) is characterized by the rapid destruction of intravenously injected allogeneic lymphocytes by unsensitized hosts. While ALC has been reported in several mammalian species, it has been most extensively studied in rats. All the available in vivo and in vitro evidence points to NK cells as the effectors of ALC. The experiments described in this communication show that when donor and host share common ALC determinants, the extent to which allogeneic lymphocytes are killed is greatly reduced, and sometimes even abolished, relative to the killing that would have occurred in the absence of shared determinants. Thus, allogeneic lymphocyte transfers in inbred rat strain combinations having the general pattern A----B are associated with significantly higher levels of ALC than are the corresponding (A x B)F1----B, A----(A x B)F1 or (C x A)F1----(C x B)F1 lymphocyte transfers. The reduced ALC is not due to inability of the F1 hybrid to respond with the full vigor of the parental strains. Nor is it due to an absolute requirement for homozygous presentation of the donor ALC determinants. It is concluded that impaired self-recognition may be an important determinant of killing in ALC, as in some other NK cell-mediated phenomena. Although ostensibly differing immunogenetically from hybrid resistance in mice, ALC includes a range of patterns of reactivity, some of which are similar to those that characterize hybrid resistance. It is suggested that hybrid resistance and ALC may represent quantitative variants of a similar process.

Animals↗