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PubMed1993

Retrovirus insertion into herpesvirus: characterization of a Marek's disease virus harboring a solo LTR.

We recently reported the phenomenon of retroviral insertion into a herpesvirus (Isfort et al., (1992) Proc. Natl. Acad. Sci. USA 89, 991-995). We have now isolated Marek's disease virus (MDV) clones that carry retroviral inserts. Retroviral LTR insertion has the potential to activate or inactivate herpesvirus genes leading to alterations of the biological properties of the herpesviruses. The structure and the expression pattern of a virus clone carrying a solitary LTR insertion was characterized in detail. The LTR insertion is accompanied by deletions in the herpesvirus genome at each of the junctions of the short unique region (US) and its inverted repeats (RS). This results in a significantly truncated RS region. Despite these structural rearrangements, the virus is replication-competent and demonstrates an enhanced growth rate in vitro. While the MDV homologs of herpes simplex US genes are retained in this virus, at least two open reading frames are deleted and one transcript observed in wild-type virus is disrupted. In addition to defining several regions of MDV that are nonessential for in vitro growth, this clone illustrates one way in which retroviral information can be stably transmitted by a herpesvirus.

Animals↗
PubMed1991

Insertion of cellular sequences in the genome of bovine viral diarrhea virus.

The genomic sequences of four pestiviruses, two BVDV strains (Osloss and NADL, both of which are cytopathogenic) and two HCV strains, were analyzed. Comparative studies revealed the presence of small insertions of cellular sequences in the genomes of both BVDV strains; the insertions are located in a region coding for a nonstructural protein. Such insertions are not present in the HCV sequences. The insertion identified in BVDV Osloss encodes a complete ubiquitin-like element. The sequence inserted in the BVDV NADL genome shows no homology to a ubiquitin gene but is almost identical with another bovine mRNA sequence. Molecular characterization of a BVDV "pair", isolated from an animal with mucosal disease, led to the detection of a ubiquitin-like sequence in the genome of the cytopathogenic strain, but not of the noncytopathogenic strain. It is proposed that recombination between viral and cellular RNA leads to formation of cpBVDV genomes. This hypothesis has direct implications for the pathogenesis of mucosal disease.

Amino Acid Sequence↗
PubMed1990

Complete reversions of a gypsy retrotransposon-induced cut locus mutation in Drosophila melanogaster involving jockey transposon insertions and flanking gypsy sequence deletions.

We have analysed the structures of three phenotypic revertant alleles of a gypsy retrotransposon-induced mutation at the cut locus of Drosophila melanogaster. All three revertants are associated with the insertion of jockey transposons into a common region of gypsy. Two of these alleles are complete reversions to wild type. One complete revertant (ct+D) is derived from a third allele, a partial revertant (ctMRpD) by a deletion of part of the gypsy sequence flanking the jockey transposon. Sequence differences between the jockey elements in ctMRpD and ct+D suggest that this deletion may have been created by the insertion of a second jockey near to the first, followed by recombinational excision of a composite jockey and the region between the two genetic elements. The other complete revertant also carries a deletion of gypsy DNA flanking the jockey insertion. The deleted regions of both complete revertants and the target region for all the jockey insertions contain a repeated sequence that resembles a transcriptional enhancer. The strength of the cut phenotype in these mutants correlates with the proportion of this region remaining near the gypsy transcriptional start site, suggesting that the jockey insertions relieve the gypsy-induced mutation at cut by interfering with a region which is required for the transcriptional competence of gypsy.

Alleles↗
PubMed1981

Isolation and properties of Tn10 insertions in the rac locus of Escherichia coli.

Two Tn10 insertions that are in the rac locus of the chromosome of Escherichia coli have been isolated and characterized. The insertions are located at min 29.7 and min 30.0. The insertions are stable when an F123 rac::Tn10 episome is transferred to an F- rac+ recipient, but they are lost at a high frequency when transferred to an F- rac- recipient. This latter condition has been previously demonstrated to cause the excision of the rac locus. The Tn10 insertions are also lost at a high frequency when strains containing them are lysogenized with lambda reverse. If the lysogens that have lost the Tn10 insertion are subsequently cured of lambda reverse, the cells no longer contain sequences homologous with rac locus DNA. These strains were rac- when tested for recombination activation (Low 1973), and this procedure consequently provides a simple means to make isogenic rac+ and rac- strains.

Chromosome Mapping↗
PubMed1991

DNA sequence of the Doc retroposon in the white-one mutant of Drosophila melanogaster and of secondary insertions in the phenotypically altered derivatives white-honey and white-eosin.

We analysed the structure of the white locus of Drosophila melanogaster in a family of related white mutants. The white-one mutant has bleach white eyes, and a Doc transposable element is inserted into the promotor region of the white locus. The DNA sequence of this Doc insertion was determined, and showed it to be closely related to other Drosophila melanogaster retroposons such as the I factor and the F, G and jockey elements. There are two long open reading frames, which encode a putative nucleic acid binding protein and a putative reverse transcriptase, respectively. Two independent, partially pigmented derivatives were analysed by cloning sequences from this region. In white-honey a transposable element of the retroviral class, B104, is inserted within the Doc element. In white-eosin there is an insertion within the Doc element of a 190 bp sequence that appears to be a member of a novel family of transposable elements. This pogo element is of the same structural class as the Drosophila melanogaster P and hobo elements. These data are consistent with the hypothesis that the Doc retroposon cannot excise, and that, for the white-one mutation, flies with altered phenotypes are most often generated by the insertion of additional transposable elements.

Amino Acid Sequence↗
PubMed1995

Changes in the chromosomal insertion pattern of the copia element during the process of making chromosomes homozygous in Drosophila melanogaster.

In situ hybridization on polytene chromosomes of Drosophila melanogaster was used to compare the insertion patterns of copia and mdg1 transposable elements on chromosome 2 in male gametes sampled by two different methods: (i) by crossing the males tested with females from a highly inbred line with known copia and mdg1 insertion profiles; (ii) by crossing the same males with females from a marked strain, and analysing the resulting homozygous chromosomes. Crossing of the males with the inbred line led to homogeneous insertion profiles for both the copia and mdg1 elements in larvae, thus giving an accurate estimation of the patterns in the two gamete classes of each male. Crossing with the marked strain led, however, to heterogeneity in insertion patterns of the copia transposable element, while no significant polymorphism was observed for mdg1. The use of balancer chromosomes is thus not an adequate way of inferring transposable element insertion patterns of Drosophila males, at least for the copia element. This technique could, however, be powerful for investigating the control of movements of this element.

Animals↗
PubMed1983

The use of transposon insertion zdc-235::Tn10 (min 32) to clone and delete DNA from the terminus region of Escherichia coli.

Transposon zdc-235::Tn10 is inserted at min 32 on the genetic map of Escherichia coli, and we have used this transposon to clone 14 kb of DNA that flanks this insertion. The site of insertion of the transposon, and the restriction map of the cloned DNA, correspond well with the predictions of the Bouché restriction map for the terminus region (Bouché 1982). The zdc-235::Tn10 insertion, along with the zdd-230::Tn9 insertion, was used to obtain deletions of the region that has been cloned. Strains lacking a minimum of 14 kb, and more likely a minimum of 40 kb of DNA, showed no alteration of growth or cell morphology.

Chromosome Mapping↗
PubMed1988

A selection cartridge for rapid detection and analysis of spontaneous mutations including insertions of transposable elements in Enterobacteriaceae.

We present a method that allows positive selection and rapid analysis of mutations in Enterobacteriaceae. Mutations are detected in a 2630 bp selection cartridge inserted in two different bacterial multicopy plasmid vectors. Spontaneous mutations in Escherichia coli, Enterobacter cloacae and Citrobacter freundii include insertions, deletions and point mutations. The small size of the target sequence facilitates rapid analysis of DNA rearrangements by cleavage with restriction enzymes and of any type of mutation by DNA sequence analysis. While in E. coli insertions of the mobile elements IS1, IS2 and IS5 were readily found, insertions of putative new transposable elements were detected in Enterobacter cloacae. The selection cartridge can thus serve as a tool for studying the spectrum of insertion mutations in Enterobacteriaceae and probably other Gram-negative bacteria, and the dependency of this spectrum on physiological and environmental factors and the host's genetic background can be investigated.

Base Sequence↗
PubMed1987

A cloned DNA fragment from bacteriophage P1 enhances IS2 insertion.

A 1.75 kb DNA segment of the bacteriophage P1 genome is known to serve as a preferred target for IS2 insertions. The presence of this fragment in a plasmid expressing the galK gene dramatically increases the proportion of IS2 insertions among spontaneous galK- mutants. Subfragments from two different parts of the 1.75 kb segment independently stimulate IS2 insertion, while another subfragment does not. In the plasmids studied IS2 elements not only insert into the cloned P1 fragment but also into parts of the galK gene with similar probability and mostly in one orientation. Many insertion sites are unique but several specific sites within the preferred target are repeatedly used for IS2 integration. The experimental data are compatible with a proposed cooperative mechanism, according to which more than one attracting sequence on the same plasmid might significantly enhance the probability of a particular target region to attract IS2.

Cloning, Molecular↗
PubMed1979

Altered linkage values in phage P22--mediated transduction caused by distant deletions or insertions in donor chromosomes.

The effects of distant deletions or insertions in the Salmonella typhimurium donor strains on P22--mediated cotransducibility of genetic markers was studied. We found that deletions of histidine operon, unit 44 of the chromosome map, changed the linkage of markers purF and aroC (unit 49) and pyrF and trpA (unit 34). They did not change the linkage of more distant markers pyrE and cysE. The effect of three types of insertions was examined. The donor strains carried F factor, Tn10 transposon or pi-his duplication inserted close to histidine operon. These insertions caused alteration of purF-aroC linkage while pyrF-trpA cotransduction values were not affected. These data show that the effect of the chromosome rearrangements extends to at least 5% of S. typhimurium chromosome length and may reach as much as 10% of it. Our results are in agreement with the model of Chelala and Margolin (1974) concerning formation of transduction particles. They indicate that the cotransducibility changes caused by deletions or insertions extent further than it might have been expected from previous reports.

Chromosome Deletion↗
PubMed1976

[Critical remarks on the symptom of "thought insertion" (author's transl)].

"Thought insertion" is one of Kurt Schneider's first rank symptoms of schizophrenia. Earlier, Karl Jaspers had made a finer distinction, differentiating between "thought insertion in a narrower sense" and "made thoughts." However, most German and English writers have dispensed with the Jasperian criteria for this differentiation and consequently their use of the term "thought insertion" is broader. Such authors, including Kurt Schneider and Weitbrecht, usually speak of "thought insertion", "made thoughts", and "influencing of thoughts" as if they were identical phenomena. In contrast, Jaspers' differentiation offers us the possibility of more clearly distinguishing such symptoms and thus his distinction should not be neglected. Furthermore, the Jasperian criteria can be logically and usefully extended to all "made and passivity experiences" enabling one to recognise four aspects of such phenomena. Some general differential diagnostic considerations with respect to "thought insertion" are then presented.

Humans↗
PubMed1996

Ability of various inserts to promote endothelium cell culture for the establishment of coculture models.

To select an insert suitable for human umbilical vein endothelial cell (HUVEC) culture, we compared several available inserts of 0.2 to 0.45 micron porosity: Cellagen (ICN), Transwell-COL (Costar), Millicell-HA and CM (Millipore), Anopore (Nunc), Cyclopore (Falcon) in comparison with a control surface (Thermanox). The requirements were: (i) to promote attachment, adhesion and proliferation of HUVEC (judged by [3H]thymidine incorporation into DNA at days 1, 3, 7); (ii) to allow HUVEC visualization by inverted, fluorescence microscopy for uptake of DiI-Ac-LDL and scanning electron microscopy, performed at day 9 after seeding. Because Transwell and Cellagen are collagen precoated and CM has to be coated for cell culture, we performed collagen coating (types I + III or IV) for non-pretreated inserts for the purpose of comparison. Our preferences comprise Transwell-COL, Cyclopore not coated or coated (whatever the collagen type), and Cellagen. However, on a quality/price ratio criterion, Cyclopore, even uncoated, is the insert of choice. The HA, CM and Anopore inserts, even coated, do not allow HUVEC growth but do not alter positive uptake of acetylated LDL.

Cells, Cultured↗
PubMed1996

Fixation strength of interference screw fixation in bovine, young human, and elderly human cadaver knees: influence of insertion torque, tunnel-bone block gap, and interference.

A failure analysis of interference screw fixation was performed to test the hypothesis that bovine and/or elderly human cadavers are appropriate models for bone-patellar tendon-bone anterior cruciate ligament (ACL) reconstruction fixation studies. Failure mode is an important criterion for validating experimental models. The bovine, young human, and elderly human failure loads were 799 +/- 261 N, 655 +/- 186 N, and 382 +/- 118 N, respectively, and the failure modes were 75%, 69%, and 30% tissue failures, respectively. The similarities between the bovine and young human models in failure loads and failure modes indicate that bovine models are appropriate for ACL reconstruction fixation studies. The statistically significant differences between the young human and elderly human models in failure loads and failure modes indicate that elderly human cadavers are not an appropriate model for ACL reconstruction fixation studies. The differences in failure modes are consistent with previous studies using elderly human cadavers in which the predominant failure mode was bone block pullout. The tissue failures observed in the bovine and young human models contradict previous studies suggesting fixation strength is the weakest link in bone-patellar tendon-bone ACL reconstruction. Results of linear regression modeling showed statistically significant correlations between insertion torque and failure load (R2 = 0.44, P < 0.0001) and interference (defined as the screw outer thread diameter minus the tunnel-bone block gap) and insertion torque (R2 = 0.18, P = 0.003) when data from all models was combined. Results for the bovine model multiple regression showed a statistically significant regression of insertion torque (linear) and interference (quadritic) versus failure load (R2 = 0.56, P = 0.02). Regression slopes for screw diameter (P = 0.52) and gap size (P = 1.00) were not statistically significant. These results indicate that insertion torque and interference are independent predictors of failure load and should be included in future interference screw studies in addition to bone block dimensions, tunnel size, gap size, and screw diameter. Clinicians may consider using insertion torque and interference as indicators of postoperative graft fixation regarding rehabilitation decisions.

Adult↗
PubMed1986

IUD insertion at cesarean section--the Chinese experience.

This review reports the experience of nine studies in Chinese maternity hospitals with insertions of an intrauterine device (IUD) at the time of cesarean section. In contrast to the usually high expulsion rates associated with immediate postpartum vaginal insertions, all nine studies reported low expulsion rates, thus resulting in high continuation rates with this procedure, comparable to those with interval insertions. This immediate post-cesarean section insertion procedure was also found to be safe. These findings are of programmatic importance for postpartum family planning delivery services and may eventually lead to an understanding of the expulsion mechanism in postpartum IUD contraception. Results of these reports have been synthesized in this review. Seven of these nine reports were originally in Chinese and were translated into English for the benefit of a broad international audience. Future research directions on this insertion procedure are also discussed.

Adult↗
PubMed1987

Rare events occurring at insertion of an intrauterine device--a review of an international experience.

Events occurring at the time of insertion of an intrauterine device (IUD) are rarely studied, especially for parous women for whom, in theory, IUD contraception is most suitable. These events, although rare, cause personal distress, embarrassment and inconvenience and can have a negative impact on IUD acceptance. Sixty million women worldwide are using IUDs. Thus, even a rare event may have important public health implications. To avoid such occurrences, the risk factors of these rare events need to be delineated. The large international IUD data set compiled by Family Health International (FHI) since 1972 provides a unique opportunity to achieve this purpose. Four IUD insertion-related rare events have been studied, namely: insertion failure, uterine perforation, syncope and other vasovagal reactions, and severe insertional pain. This review paper summarizes the important findings from these as well as other relevant studies. This broad experience should form the basis by which health personnel inserting IUDs can improve the quality of care for women requesting a device for contraception.

Adult↗
PubMed1994

Immediate postplacental insertion of the intrauterine device: a review of Chinese and the world's experiences.

The postpartum period is an ideal time to begin contraception, as women are more highly motivated to adopt contraception at this time and it is convenient for both patients and service providers. For intrauterine device (IUD) contraception, this period offers other advantages, such as ease of insertion and minimal adverse impacts on breastfeeding. Among early studies, most postpartum insertions were performed anywhere from a few hours to seven days or more after delivery, and retention of the IUD in the uterus was poor. Since the 1970s, immediate postplacental insertion (IPPI), i.e., IUD insertion performed within 10 minutes after placental delivery, has been advocated, and fairly, low expulsion rates have been reported. Up to now, IPPI has not been widely accepted in clinics because its expulsion rate still appears to be higher than that of interval insertion. In order to further study IPPI and perfect this contraceptive technique, it is essential to comprehensively review IPPI results and compare the Chinese experience with that of the rest of the world.

China↗
PubMed1983

Prolonged pulse-entry of pilocarpine with a soluble drug insert.

Apparent biophase availability of pilocarpine was studied in the eyes of albino rabbits. Pilocarpine doses of 0.85 and 2.30 mg in aqueous solutions, 1.00 mg in oil and 0.85 mg in a solid insert, were applied ocularly. The insert was a water soluble polyvinylpyrrolidone (PVP) matrix, which released 80% of its pilocarpine content in 35 min in vitro. In the inferior fornix of the eye this insert gelled in about 5 min and dissolved in 1 h. Pupillary diameters were measured and converted to values for the response parameter (RP). Time delay and magnitude of peak response, apparent biophasic availability (area under the curve of RP vs time), and a constant for the apparent rate of elimination were calculated from RP values. The time delay for the peak response was 16.l3-24.0 min, and the constant for apparent rate of elimination was 0.69-0.81 h-1. Neither time delay nor this constant was affected by the dose or the dosage form. Magnitude of the peak response and apparent biophasic availability were influenced by the vehicle and the dose: insert (0.85 mg) greater than oily solution (1.00 mg) greater than aqueous solution (2.30 mg) greater than aqueous solution (0.85 mg). The insert and oily solution did not show vehicle-controlled drug absorption and can be regarded as prolonged pulse-entry medication.

Animals↗
PubMed1996

A small insertion in the SSU rDNA of the lichen fungus Arthonia lapidicola is a degenerate group-I intron.

Insertions of less than 100 nt occurring in highly conserved regions of the small subunit ribosomal DNA (SSU rDNA) may represent degenerate forms of the group-I introns observed at the same positions in other organisms. A 63-nt insertion at SSU rDNA position 1512 (relative to the Escherichia coli SSU rDNA) of the lichen-forming fungus Arthonia lapidicola can be folded into a secondary structure with two stem loops and a pairing of the insertion and flanking sequences. The two stem loops may correspond to the P1 and P2, and the insertion-flanking pairing to the P10, of a group-I intron. Considering these small insertions as degenerate introns provides important clues to the evolution and catalytic function of group-I introns. Keywords Ribosomal DNA middle dot Small subunit middle dot 18s middle dot Degenerate introns middle dot Ascomycetes

Ascomycota↗